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To reduce the matrix hardness of diamond composites for hard rock formations, Cu-based composites with lower sintering temperature and hardness were prepared by medium-frequency induction hot press sintering in this paper, with the addition of basalt fiber particles (BFPs) of 0 wt%, 1 wt%, 3 wt%, and 5 wt%. The microstructural characterization and property tests were carried out to research the effects of BFPs on the flexural strength, hardness, densification, and wear ratio of the composite. The result shows that when the BFPs addition was 1 wt%, the holding strength of the composites was increased by 10.3 % the hardness was increased by 5.9 % compared with the blank sample, and the diamond exposure became higher in the wear ratio test. The BFPs enhance the homogeneity of the composite structure, promote the diamond exposure in the composites, improve the holding strength of the composite of the diamond, and reduce the thermal damage of diamonds in the composites. [ABSTRACT FROM AUTHOR]

To preserve the structural and interfacial integrity of diamond, diamond/SiC composites were fabricated by Si infiltration under gas flow guidance. The characteristics of these materials are significantly affected by the interfacial reaction between Si and diamond. The interface formation was studied extensively by locally analyzing the microstructure of the interfacial regions via transmission electron microscopy (TEM), field-emission scanning electron microscopy (FE-SEM), Raman spectroscopy, and X-ray diffraction (XRD). The results demonstrated that the extent of reactive erosion of diamond by Si weakened as the gas velocity increased during the infiltration process. Nanocrystalline Si 5 C 3 and β-SiC grains with an orientation relationship were observed at the diamond/SiC interface. Furthermore, by employing gas flow guidance, the diamond/SiC composites exhibited a better specific stiffness, measuring up to 183.3 × 106 m2 s−2, which represents an exceptional 18 % improvement compared with the control group. [ABSTRACT FROM AUTHOR]

Diamond/SiC composites offer valuable applications in thermal management because of their exceptional thermal properties. Currently, the predominant method employed for crafting diamond/SiC composites is the reaction sintering approach. However, it encounters the challenge of a high residual silicon content. In this study, we introduced techniques such as bimodal diamond particles and high-density carbon sources (submicron diamond powder) to enhance the diamond content and reduce the residual silicon, optimizing the phase composition. The results indicated the diamond/SiC composite demonstrated a thermal conductivity of 666 W/m·K, a thermal expansion coefficient of 2.73 × 10−6 K−1, and an elastic modulus of 753 GPa. Furthermore, the meticulous assessment of the interface microstructure of diamonds in the diamond/SiC composite was conducted using transmission electron microscopy. The formation of nanocrystal-SiC and interface defects were elucidated by the mechanism of carbon dissolution saturation. [ABSTRACT FROM AUTHOR]

We use P t and C t to denote a path and a cycle on t vertices, respectively. A diamond is a graph obtained from two triangles that share exactly one edge. A kite is a graph that consists of a diamond and another vertex adjacent to a vertex of degree 2 of the diamond. A gem is a graph that consists of a P 4 plus a vertex adjacent to all vertices of the P 4. Choudum et al. (2021) proved that every ( P 7 , C 7 , C 4 , gem)-free graph has either a clique cutset or a vertex whose neighbors is the union of two cliques unless it is a clique blowup of the Petersen graph, and every non-Petersen ( P 7 , C 7 , C 4 , diamond)-free graph has either a clique cutset or has a vertex of degree at most max { 2 , ω (G) − 1 }. In this paper, we extend these two results respectively to ( P 7 , C 4 , gem)-free graphs and ( P 7 , C 4 , diamond)-free graphs. We also prove that if G is a ( P 7 , C 4 , kite)-free graph with δ (G) ≤ ω (G) and without clique cutsets, then there is an integer ℓ ≥ 0 such that G = K ℓ + H , where H is either the Petersen graph or a well-defined graph F. This implies a polynomial algorithm which can determine the chromatic number of ( P 7 , C 4 , diamond)-free graphs, color ( P 7 , C 4 , kite)-free graphs G with (ω (G) + 1) colors, and color ( P 7 , C 4 , gem)-free graphs G with (2 ω (G) − 1) colors. [ABSTRACT FROM AUTHOR]

RBSC with a low residual Si less than 5 vol% was fabricated using SiC–C preform with diamond as a main carbon source by a conventional reaction sintering process at the temperature range between 1500 °C and 1800 °C. The diamond content in the SiC–C preform varied from 10 wt% to 17 wt%. The diamond as the main carbon source used in SiC–C preform effectively minimized the residual Si in RBSC by increasing the reaction of diamond due to the enhanced Si melt infiltration even in SiC–C preform with high carbon content. The Si melt infiltration should be performed above 1600 °C for the complete reaction of diamond particles with size of 0.5 μm because of the relatively low dissolution rate of diamond in Si melt. The flexural strength of RBSC with residual Si content less than 7 vol% exceeded 400 MPa. The flexural strength of RBSC was increased with decreasing residual Si content, but sharply decreased by the residual carbon accompanying pores in RBSC. RBSC with low residual Si content displayed moderate flexural strengths around 200 MPa even above Si melt temperature because of the formation of continuous SiC structure in RBSC by the enhanced grain growth of SiC. Vickers hardness of RBSC was steadily increased from 17.7 GPa to 24.6 GPa with decreasing residual Si. [ABSTRACT FROM AUTHOR]

A series of high-pressure multi-anvil experiments were conducted in the MgO-Al 2 O 3 system between 15 and 50 GPa and at temperatures up to 2623 K, to determine the solubility of Al 2 O 3 in periclase in the stability fields of coexisting spinel, corundum, the Mg 2 Al 2 O 5 modified ludwigite phase, the MgAl 2 O 4 calcium ferrite phase, and the MgAl 2 O 4 calcium titanate phase. The Al 2 O 3 solubility in periclase is strongly temperature-dependent over the conditions investigated. Conversely, periclase Al 2 O 3 solubility exhibits a negative relationship with pressure. Experiments with up to 40 mol.% FeO in ferropericlase show Al 2 O 3 solubilities that are near identical to those of periclase, within experimental uncertainties. A simple thermodynamic model incorporating significant literature on ambient pressure measurements is able to describe periclase Al 2 O 3 solubility up to 40 GPa. This model is used to investigate the Al 2 O 3 contents of ferropericlase inclusions observed in natural diamonds, which vary up to 0.35 mol. %. Pressure–temperature curves along which particular inclusions formed can be produced if equilibrium can be assumed with Al-bearing minerals found in the same diamond. Alternatively, the maximum possible Al 2 O 3 content in ferropericlase can be determined for a certain pressure–temperature profile and inclusions with Al 2 O 3 contents that exceed this curve can be excluded from those conditions. To obtain such solubility curves, calculations are performed for periclase coexisting with the Al-rich phases spinel, garnet, bridgmanite and the MgAl 2 O 4 calcium ferrite phase. The calculations indicate that periclase, and by inference ferropericlase, Al 2 O 3 -contents cannot be greater than 0.5 mol.% under present day adiabatic mantle temperatures and go through a minimum at mantle transition zone conditions. This excludes a number of Al-rich ferropericlase inclusions found in natural diamonds from being formed in the transition zone, unless temperatures were super-adiabatic. This subset of inclusions likely formed either at the base of the upper mantle or the top of the lower mantle, but must have formed at near adiabatic temperatures. The majority of ferropericlase inclusions have Al 2 O 3 contents that would be consistent with formation in the transition zone at near slab temperatures, but could still have been formed at higher temperatures if Al 2 O 3 activities were low. [ABSTRACT FROM AUTHOR]

The hardness and brittleness of binderless tungsten carbide, make it difficult to fabricate microlens array (MLA) on it. In this paper, an integrated milling-grinding machining method was used to fabricate MLA on binderless tungsten carbide. A model for predicting the relationship between surface roughness and undeformed chip thickness during the integrated milling-grinding process was proposed. Microgroove machining experiments confirmed the relationship between surface roughness and undeformed chip thickness, which showed that the ductile-brittle transition boundary was divided. Based on this, an MLA was fabricated in the ductile mode, and the surface roughness of a single lenslet was approximately 16 nm. This integrated milling-grinding machining method is shown to be available for fabricating MLAs on hard substrates. • It is hard to fabricate microlens array on binderless tungsten carbide, integrated milling-grinding is proposed. • The integrated milling-grinding contains milling of the tool edge and grinding of the diamond grains. • Microgroove machining experiments validates the relationship between surface roughness and undeformed chip thickness. • Lenslets with high surface quality and little tool wear are obtained after machining microlens array. [ABSTRACT FROM AUTHOR]

Material removal mechanisms are essential for the selection of polishing slurries and parameter optimization of chemical–mechanical polishing (CMP) processes. This study established a material removal rate (MRR) model for CMP of single-crystal SiC substrates using a fixed agglomerated diamond (AD) abrasive pad (FADAP). The distribution of the polishing pressure between the AD abrasive and FADAP matrix was examined, and the influence of the abrasive and polishing parameters on the MRR was revealed. Furthermore, single-factor experiments were conducted to validate the rationality of the MRR model. The experiments demonstrated that when the thickness of the surface-affected layer of the single-crystal SiC substrate in the MRR model was set to 5 nm, the error between the calculated and experimental values of the model could be controlled to within 20%. This result experimentally verified the validity of the MRR model and its associated assumptions. Moreover, the MRR of the CMP process of a single-crystal SiC substrate reached 36.26 μm/h with a polishing pressure of 27.6 kPa and an AD abrasive primary particle size range of 7–10 μm. Therefore, the feasibility of efficiently processing single-crystal SiC substrates using an FADAP was theoretically confirmed. [Display omitted] • A material removal rate (MRR) model for chemical mechanical polishing (CMP) of fixed agglomerated diamond abrasive pad (FADAP) containing the affected layer on the workpiece surface was established. • Theoretical calculations and analysis were conducted on the concession distance of the agglomerated diamond (AD) abrasives in the FADAP. • The real-time thickness of the surface affected layer during single-crystal SiC substrate CMP process was computed based on the MRR model. [ABSTRACT FROM AUTHOR]

SiC p /Al composites are suitable for satisfying the lightweight requirements of terahertz wave-reflecting components. In this paper, diamond-turned surfaces of 60 % high volume fraction SiC p /Al composites are characterized in terms of surface roughness and terahertz reflectivity. The finished surfaces of SiC p /Al composites are obtained using single-point diamond turning with different process parameters, and surface roughness measurements as well as SEM and EDS analyses are conducted on the surfaces. The theoretical relationship between surface roughness and terahertz reflectivity is analyzed, and terahertz reflectivity testing experiments are conducted and validated. The surface roughness evaluation system and prediction model for SiC p /Al composites with a volume fraction of 60 % are established, and the errors between the experimental results and the predicted results are verified within 10 % by random experiments. Finally, the turning process parameters are optimized using a genetic algorithm, and the optimized turning process parameters are obtained as the spindle speed of 750 r/min, the feeding speed of 1 mm/min and the turning depth of 6 μm. • Spindle speed and feeding speed have a significant impact on surface roughness. • The relationship between roughness and reflectivity was analyzed and experimented. • Roughness prediction model is established, and the model error is verified. • A genetic algorithm is adopted to optimize the turning process parameters. [ABSTRACT FROM AUTHOR]

In this contribution, we are interested in the prediction of the macroscopic thermal conductivity of three-phasic composite materials such as wood fibers. The main idea is to make use of up-scaling such as homogenization to link the pore scale and the sample scale. The studied wood species incorporates three phases: the air, the lumen or matrix and the fibers. Image processing is preformed on a tomographic acquisition with high resolution of some micrometers. It serves to identify the present phases and generates the morphology mesh. The 2D diamond scheme is employed to discretize Fourier's model posed on the segmented morphology. The resulting algorithm is validated using an exact solution. Optimal numerical convergence rates of second order are recorded. The thermal conductivity is therefore estimated following the 2D orthotropic directions. An emphasis is set on the impact of the orientation of fibers on this thermal property. [ABSTRACT FROM AUTHOR]

Reaction-bonded boron carbide composites were fabricated by molten silicon infiltration of diamond-containing boron carbide preforms. The effects of diamond particle size on the microstructure, mechanical and tribological properties of reaction-bonded boron carbide composites were investigated. Fine diamond particles (≤7.7 µm) completely reacted with silicon generating nano silicon carbide particles, which bonded the boron carbide particles forming a 3-D ceramic skeleton and improving the flexural strength of the composites. Coarser diamond (≥24 µm) particles were retained protected by a dense SiC layer generated from the reaction of diamond and molten silicon. A "core-shell" structure with the retained diamond as the "core" and with the reaction formed silicon carbide as the "shell" formed. Relief structures were established on the composites' surface during the wear process, greatly reducing the friction coefficient and improving the wear resistance. [ABSTRACT FROM AUTHOR]

Polycrystalline diamond compacts (PDC) with three different substrate geometries and trimodal diamond particle formulation were fabricated. The properties of prepared PDC including Vickers hardness, toughness, wear performance, and thermal stability were evaluated. The microscopic features including morphology, elemental and phase composition, and residual stress state were systematically investigated. The optimal substrate contributing to best comprehensive properties of PDC was singled out. Discrepancies in the properties of PDCs with different substrate geometries were mainly in fracture toughness and impact toughness, with maximum and minimum values of 6.54 MPa m1/2/3120 J and 5 MPa m1/2/1680 J, respectively. The best wear performance was 5.88 mm2/60P. The results showed that the tendency of wear performance was consistent with toughness and thermal stability, showing a strong correlation. The substrate geometry affected the morphology and composition of the cobalt transition layer in the interface, which had a significant impact on its toughness. Differences in residual stress states induced by the interfacial geometries were also important determining PDC's impact toughness. [ABSTRACT FROM AUTHOR]

Silicon carbide (SiC)-bonded diamond materials, comprising approximately 50% diamond by volume, represent innovative composites with exceptional mechanical and thermal properties, including high hardness, wear and corrosion resistance, and elevated thermal conductivity. Despite these advantageous properties, the machining of these composites presents formidable challenges due to their extremely high hardness. Grinding with diamond tools is commonly employed among the limited viable machining methods. However, the efficiency of this process is hindered by high grinding forces, elevated temperatures, and significantly high tool wear. Additionally, the surface integrity, form, and dimensional accuracy of the workpiece are compromised by the effects of tool wear and high cutting forces. To address these technological constraints in the grinding of SiC-bonded diamond materials, a laser-assisted grinding process has been developed. Ultra-short pulsed laser radiations were effectively utilized to induce material ablation with controlled structural damages, enhancing the productivity and efficiency of the grinding process through reduced grinding forces, temperatures, and tool wear. Furthermore, this study investigated the influence of grinding tools' specifications, design variations, and parameters on key aspects such as grinding forces, surface quality, and tool wear. Substantial reductions of up to 70% in tangential grinding forces, 83% in normal grinding forces, and a modest improvement in surface roughness achieved. The surface integrity analysis revealed a damage-free ground surface when utilizing laser assistance. Furthermore, there was a substantial enhancement in the grinding ratio (G-ratio), achieving an increase of up to 247%, concurrently with a noteworthy improvement in the actual removal depth, reaching up to 99%, when compared to conventional grinding processes. Compared to the utilized segmented metal bonded diamond grinding wheel, the vitrified bonded diamond grinding wheel induced lower grinding forces and higher actual removal rates. [ABSTRACT FROM AUTHOR]

Polycrystalline diamond compacts (PDCs) with varying amounts of vanadium were successfully sintered. The mechanical and thermal performance tests showed that the abrasion resistance, impact toughness, and thermal resistance increased by 69%, 202.9%, and 30 °C, respectively. The improved performance can be attributed to the solid solution formed by V 8 C 7 with tungsten carbide (WC) as a reinforcing phase, which eliminated interfacial defects, improved residual stress, and reduced the thermal expansion coefficient. In summary, we successfully developed a novel method for fabricating high-performance PDCs to enhance abrasion resistance and thermal stability, while substantially improving impact resistance, and which have remarkable application prospects. [ABSTRACT FROM AUTHOR]

Diamond is a fascinating material with exceptional optical and electronic properties, making it a highly desirable material for various applications. Herein, the effect of various types of defects and their concentration the optical and electronic properties of diamond is investigated and discussed. Using Boron and Nitrogen as dopants, we demonstrate how the electronic band structure can be tailored to achieve specific optical and electronic properties without compromising the crystal structure. Furthermore, Hydrogen interstitial defects enable the manipulation of the band structure and provide a better understanding of the correlation between band structure, density of states, and optical properties. Moreover, the validity of selected structures with high desirable electronic and optical properties as Hydrogen and oxygen evolution catalysts was explored and discussed. • N, B, and H dopants improved the efficacy of diamond catalytic properties. • Both type and concentration of dopant are significantly important. • 2B-2N-doped diamond showed a band gap energy of 2.35 eV. • The 3B-N-H structure is a good oxygen evolution reaction (OER) catalyst. • 3B&2H structure is a good hydrogen evolution reaction (HER) catalyst. [ABSTRACT FROM AUTHOR]

In this paper, porous single-crystal diamond with boron doping were synthesized by adding TiB 2 to the Fe–Ni–C system at a pressure of 5.6 GPa and a temperature of 1360 °C. The boron and nitrogen impurities were investigated in depth along with the surface defects of the diamonds. The results indicate that when the TiB 2 content was within the range of 0–10 wt%, an increase in the doping concentration of TiB 2 can lead to a decrease in the nitrogen content and an increase in the boron content in the diamond, causing the crystal color to transition from yellow to pale yellow, pale yellow-blue, and black. When the TiB 2 content was within the range of 20–40 wt%, several triangular concave porous structures appeared on the crystal surface. With an increase in the TiB 2 addition, the side length of these triangular pits decreased from 2.85 μm to 1.09 μm, while their depth decreased from 590 nm to 50 nm. The roughness of the crystal surface measured by Rq demonstrated values up to 145.302 nm. The results indicate that the size, depth, and density of the triangular defects can be adjusted by the amount of additive TiB 2. Our findings provide insights into the surface regulation and functionalization of boron-doped diamond single crystals. [ABSTRACT FROM AUTHOR]

In this paper, the self-propagating reaction of the Ti–SiC–C system for synthesising Ti 3 SiC 2 -based diamond composites is ignited by the combustion of Ni–Al alloy powders in a microwave field. The heating curves of Ni–Al-assisted microwave sintering show that the self-propagating reaction could be successfully ignited after heating samples to 685.2 °C in a microwave field for 456 s. This finding indicates that ignition could occur at temperatures below the diamond graphitisation temperature (727 °C). X-ray diffraction analysis indicates that the sintered samples primarily comprise Ti 3 SiC 2 , TiC, Ti 5 Si 3 and C. Scanning electron microscopy coupled with energy dispersive spectroscopy observations demonstrates that the diamond grains are tightly bonded with the surrounding matrix and are intact. The best wear ratio of 302.26 was obtained for the Ti 3 SiC 2 -bonded diamond composite when the diamond grain size was 140/170 mesh and the molar ratio of Ti, SiC and C was 3:1.1:0.9. [ABSTRACT FROM AUTHOR]

A novel transient liquid phase bonding (TLP) method for obtaining high-temperature resistant diamond/Cu joint was designed. The joint was achieved through the isothermal solidification of Au–Si interlayer assisted by the diamond active modified layer and NiTi particles. The interfacial reaction mechanisms in the TLP process were systematically investigated in this study. The results shown that Ti 5 Si 3 C, CuTiSi and NiTiSi precipitated from the seam. Due to the precipitation of Si and the interdiffusion of Au–Cu, a ductile Au–Cu solid solution ((Au, Cu)ss) matrix formed. The shear strength of the diamond/Cu joint was notably affected by the holding time. The maximum room-temperature shear strength of 108 MPa was achieved when the joints were held at 600 °C for 60 min, and the high-temperature strength was still up to 22 MPa at 600 °C. The high strength of the joints was achieved because of (i) the elimination of the Cu(Au)–Si brittle phases, (ii) the NiTiSi whiskers pulling-out mechanism, and (iii) the moderate distribution of compounds at the diamond/seam interface. [ABSTRACT FROM AUTHOR]

To improve the processing performance of vitrified bonded diamond fixed-abrasive lapping plates for processing sapphire substrates, a free-abrasive was added to the lapping slurry to enhance the self-dressing ability of the lapping plate to achieve efficient and high-quality processing of sapphire substrates. The processing effectiveness and mechanism of a free-abrasive assisted fixed-abrasive lapping plates (FAAFALP) lapping process for sapphire substrates were analysed and revealed via a single-factor experiment. To optimise the lapping process of the FAAFALP of sapphire substrates with good overall performance (high material removal rate (MRR), minor surface roughness (Ra) and big lapping plate wear ratio (η)), the effects and the optimal parameters combination of the lapping pressure, lapping speed and free-abrasive concentration on MRR, Ra and η of lapping-processed sapphire substrates were investigated using orthogonal experiments. Furthermore, the experimental results were combined with process parameters to establish a regression model. The multi-evaluation index optimisation problem was transformed into a single-index optimisation problem via the grey relational analysis (GRA) to evaluate each parameter's performance comprehensively. The results revealed that an MRR increased by 22.2 % to 2.48 μm/min, the smallest surface roughness Ra of 0.141 μm, and the lapping plate wear ratio η relatively increased to 14.88 was obtained when a free-abrasive of SiO 2 with a particle size of 14 μm was added into lapping slurry. Compared with no free-abrasive lapping process, free-abrasive can significantly improve the lapping plate's self-dressing ability and enhance the sapphire substrates' processing effect. The lapping speed, lapping pressure and free-abrasive concentration had different influence degrees on MRR, Ra and η. The established regression equations predicted the response values of MRR, Ra and η to be 99.87 %, 99.06 % and 98.59 %, respectively, and the relative errors between the predicted and actual measured values were <12 %. With increased lapping speed, MRR initially decreased but subsequently increased, and Ra and η gradually decreased. MRR and η continuously increased with increased lapping pressure, whereas Ra decreased. With increased free-abrasive concentration, MRR, Ra and η initially increased but subsequently decreased. Comparing the optimised results obtained by intuitive analysis, the parameters optimised via the GRA were used to obtain sapphire substrates lapping with an MRR of 3.81 μm/min, Ra of 0.133 μm and η of 20.4, and the overall lapping performance was better 42.92 %, 102.90 % and 43.60 % than that of intuitive analysis for MRR, Ra and η. Therefore, combining orthogonal experiments and GRA can provide new ideas for optimising the FAAFALP lapping process for sapphire substrates. • The processing effectiveness and mechanism for sapphire substrates were analysed and revealed. • Effects of process parameters for sapphire in lapping on MRR, Ra and lapping plate wear ratio were studied. • A regression model combined with experimental results and process parameters was established. • Grey relational analysis was used to obtain parameters with good lapping performance. [ABSTRACT FROM AUTHOR]

Replicating lithospheric diamonds experimentally helps reveal their histories at depth, which may be complicated by successive growth and dissolution episodes. Here, we present diamond growth and dissolution experiments to constrain the conditions of diamond formation and residence in the Earth's lithosphere before their transport to the surface. Experiments were performed on mixtures of carbonates, natural lherzolite or MORB, water, diamond seeds, and with or without graphite using multi-anvil presses over a few hours to more than a day at conditions relevant to the lithosphere (7 GPa, 1300–1670 °C). We observed growth within a volatile-rich melt resulting from the miscibility of silicate-carbonate melt and aqueous fluid via the reaction: Carbonate minerals + Silicate minerals/glasses + H 2 O = [volatile-rich melt] ± minerals + C diamond + O 2. In the absence of graphite, we observed diamond dissolution within the same hydrous-carbonate–silicate-bearing melts and under similar pressure and temperature conditions used to grow diamond, indicating that diamond formation requires an oxygen sink (graphite, metallic and/or sulphide melts). In dissolution experiments, we also observed resorption features similar to those described in lithospheric monocrystalline diamonds, which we thus attribute to mantle fluids and not to kimberlite-induced resorption during magma ascent. We show that dissolution and growth may alternate in the mantle, and that protracted periods are not necessary to explain natural diamond histories. During experimental growth, inclusions were trapped in diamonds as they are in nature. We observed both syngenetic (formed during growth, representing the parental fluid) and protogenetic inclusions (here particles from the capsule), indicating that both kinds of inclusions can be trapped within a single growth event. Our experiments confirm that inclusions trapped in natural diamonds do not necessarily represent remnants of their parental fluids and are not necessarily contemporaneous: two inclusions near each other within a single monocrystalline diamond may have different histories, and inclusions must be shown to have achieved chemical and isotopic equilibrium before being considered synchronous. [ABSTRACT FROM AUTHOR]

The calcium fluoride (CaF 2) component has excellent light transmission and a high laser damage threshold in the UV band, and thus is a potentially ideal material for high-power laser facility. However, the low-damage surface is difficult to attain via the existing processing technologies due to its brittleness, especially the dissociation property of the (111) surface. We innovatively propose H 2 O(g) plasma-assisted porous diamond abrasive lapping technology to achieve low-damage and high-precision surface processing of CaF 2 component, which means that the CaF 2 component is modified first and then the softened modified layer is removed by the porous diamond abrasive lapping. The H 2 O(g) plasma modification mechanism was elucidated through a combination of molecular dynamics simulation and experiment and comparison with H 2 O(g) plasma etching. The modification layer including an oxide layer and a phase change layer was produced by adjusting the plasma processing process (power of 25 W and H 2 O(g) content of 10 ml). Then the modified CaF 2 component was lapped by the porous diamond abrasive tool on the ductile domain layer which is more than the modified layer and less than the sum of the modified layer and plastic domain. When the lapping process parameters were 200 rpm platen rotation speed and 20 N lapping pressure, a surface accuracy of 15.34 nm PV, 2.29 nm RMS (φ1 mm) was obtained. This study provides technical support for the low-damage processing of CaF 2 component. [ABSTRACT FROM AUTHOR]

The dielectric properties and polarization mechanism are important for the application of high thermal conductivity electronic packaging materials. In this work, diamond/SiC composites were prepared by the silicon vapor infiltration process, and the effect of diamond content on permittivity of composites was investigated in detail in the range of 100 MHz to 1 GHz, and the mechanism of dielectric polarization was also discussed. The results show that the real part of permittivity of composite is greater than that of either component, due to the presence of interfaces and defects. As the diamond content increases, both the real and imaginary parts of permittivity show a trend of rapid decrease and then slow increase. Particularly, the minimum values of the real and imaginary parts of permittivity of diamond/SiC composite are 27 and 0.3, respectively. In the low frequency stage (<400 MHz), the dielectric loss of the composite is mainly caused by the conductivity loss, while in the high frequency stage (400 MHz∼1 GHz), the polarization loss plays a dominant role. The polarization loss of diamond/SiC composite mainly originates from several Debye relaxation processes, which are the interfacial polarization formed at the diamond/graphite and graphite/SiC interfaces. [ABSTRACT FROM AUTHOR]

The excellent thermal properties of diamond/SiC composites are mainly attributed to the addition of diamond particles. In order to further increase the diamond content, a novel preparation method was used to regulate the distribution of bimodal diamond particles. Moreover, in order to achieve better performance, the effects of particle size ratios on the properties were studied. The results show that with the increase of small diamond particle size, the bimodal diamond packing will change from unmixing mechanism to mixing mechanism, and the critical ratio (small/large) of entrance for 400 µm diamond particles is between 0.37 and 0.5. When the particle size ratio is 0.25, the thermal conductivity reaches the maximum, reaching 812.27 W/mK (break through 800 W/mK for the first time). In addition, the influence of particle size ratio on coefficient of thermal expansion is also discussed. [ABSTRACT FROM AUTHOR]

Fine-crystallized micro-structured surfaces have excellent physical and antifatigue properties. However, flexible fabrication of fine-crystallized micro-structured surfaces is still a challenge for current additive and subtractive machining technologies. This study proposes a high-frequency diamond imprinting (HFDI) technology and a principle for generating micro-structured surfaces based on splicing simple geometry shapes. Micro-structured surfaces, such as micro-images with anti-counterfeiting codes, microscopic QR codes and biomimetic surfaces, were successfully machined by HFDI on polycrystalline nickel. The size of subsurface grains is highly reduced from over 30 µm to less than 1 µm, and a fine-crystallized layer with a thickness of 10 µm is formed. In addition, a cross-scale coupling model of HFDI, based on discrete dislocation dynamics, is constructed to realize dynamic simulation of subsurface dislocation motion and to explore fine crystallization mechanisms. This research holds theoretical and practical significance for realizing high performance and high precision machining. [ABSTRACT FROM AUTHOR]

Evaluating surface frequency components in the fabrication process is critical for controlling the machined surface quality. The presence of anisotropic ripples on diamond-turned surfaces makes this challenging. A multiscale frequency evaluation method, referred to as Surface Intrinsic Mode Decomposition (SIMD), is proposed for evaluating on-machine surface measurement (OMSM) data. It decomposes continuous surface probing profiles, incorporating both temporal and spatial frequency information. In comparison to the conventional power spectral density (PSD) analysis method, the approach enriches frequency details over a wider range, which contributes to a more comprehensive understanding of surface quality and helps to identify mid-spatial frequency (MSF) errors. [ABSTRACT FROM AUTHOR]

Vitrified-bond diamond composites are materials commonly used for grinding wheels in the grinding process of silicon wafer production. In this study, the mechanism of the in situ honeycomb structure formation in the sintering process of composite materials was explored by changing the binder content without adding a pore-forming agent.The results show when the content of vitrified bond is 55 wt%, the in situ honeycomb structure forms, resulting in a porosity of 60.68 % and bending strength of 23.03 MPa.The X-ray diffraction (XRD), Raman spectroscopy (RS), and thermogravimetry-differential thermal analysis (TG-DTA) results show that no graphitization of diamond grain occurs during sintering. The bonding ability between the vitrified bond and diamond grain, along with the microstructure of vitrified-bond diamond composites, was studied using scanning electron microscopy (SEM). Moreover, the results of energy spectrum analysis (EDS) show that the diffusion and segregation of Na at the interface between the diamond particles and the vitrified bond improve the bonding strength, and the vitrified bond can effectively bond with the diamond particles. Finally, the formation mechanism of the honeycomb structure was elucidated using the surface and interface sintering theory. [ABSTRACT FROM AUTHOR]

Polycrystalline diamond compact (PDC) with different grain sizes were fabricated and the multi-physical behaviors, including mechanical-, thermal-, and magnetic performances, and the microscopic features were examined to study the grain size dependence of wear behavior while cutting dense granite. The results showed that the coarse grade PDC had higher impact resistance and fracture toughness. However, the fine grade PDC had higher cobalt content, hardness and thermal resistance. Among these properties, the wear resistance changed the same way as thermal expansion properties proving the strong correlation. Moreover, the crack network caused by thermal mismatch, and the peeling/fracture of metallic phases and diamond promoted fracture wear and played the critical roles in the wear of coarse grade PDC. [ABSTRACT FROM AUTHOR]

Surfaces with nanometric texture, machined by ultra-precision diamond milling (UPDM), have wide applications for their functionalities. Surface texture characterisation is crucial for their quality evaluation and it would vary in the measurement data processing under various scales, which is termed scale effects. However, the scale effects have not been comprehensively studied. In this work, we focus on the scale effects on surface texture characterisation of UPDM. Firstly, a series of experiments were conducted at different material removal rates to produce surfaces with nanometric texture. Secondly, a discrete wavelet transform (DWT)-based method was employed for surface filtering and surface texture parameters (Sa , Sq , and Sz) were evaluated according to ISO standards. Thirdly, power spectral density (PSD) analysis and surface filtering comparison were performed to realize a scale observation. Furthermore, the effects of the filtering scale, the sampling scale, and the subarea scale on surface texture characterisation were investigated. Finally, the results showed that surface topographies were governed by various machining factors which resulted in multi-scale topographical components. The PSD analysis enabled discrimination of the multi-scale topographical components to the underlying machining factors. The DWT-based method achieved a relatively small deviation (<4%) for surface filtering as compared to the zero-order Gaussian regression filter. The filtering scale affected the filtered topographical components and it visualised and differentiated those components with the machining mechanisms. The sampling scale determined the filtered components to yield an impact on the characterisation results and Sz was more sensitive to this effect than Sa and Sq. The subarea scale influenced the probability distributions and statistical values of surface texture parameters within its contained components and it indicated that the increased material removal rate resulted in a deterioration of surface uniformity. • Surfaces with nanometric texture were processed by ultra-precision diamond milling. • Discrete wavelet transform was conducted for surface filtering at multiple scales. • Surface texture parameters were characterized according to the ISO standards. • The scale effects on surface texture characterisation were investigated. [ABSTRACT FROM AUTHOR]

During the milling of a curved surface, the shape of the curved surface changes continuously along the milling path, and the direction of the angle between the axis of the milling tool and the normal vector of the machined surface also changes. In turn, these changes greatly affect the quality of the machined surface. Therefore, to improve the surface quality of machined workpieces, the milling tool inclination angle should be optimized. In the present study, a three-dimensional model of the milling tool path and the workpiece surface was created. The three-dimensional surface model of the workpiece at each machining moment was iteratively built based on the Z-map method. From the macroscopic perspective, the influences of different milling tool inclination angles on surface roughness were analyzed. The difference in surface roughness generated by different inclination angles under the same feed rate and pitch was obtained. When cutting with the top of the milling tool, the roughness was larger compared to other inclination angles, and there was a roughness deviation of about 8% when other inclination angles were selected. Moreover, from the microscopic perspective, the material removal rate from a single feed cycle and the optimal inclination angle range for milling stability were explored. An optimal inclination range of 15–30% was obtained, considering both the total material removal volume and unit-angle material removal volume. Finally, a spherical machining verification experiment was conducted on an ultra-precision machining tool, and the experimental findings agreed well with the simulation results, demonstrating the reliability of the proposed model. The theoretical model of this study can provide a basis for optimal cutting tool inclination angle selection during complex surface milling. • A surface model of the workpiece was built based on the Z-map method. • The influences of milling tool inclination angles on surface roughness were analyzed. • The material removal rate from a single feed cycle was explored. • The optimal inclination angle range for milling stability was explored. [ABSTRACT FROM AUTHOR]

Diamond/SiC composites have long been recognized as advanced materials for thermal management as they exhibit excellent thermal and mechanical properties. The objective was to investigate and understand the phase composition, diamond graphitization behavior, microstructure, and properties of diamond/SiC composites developed following the liquid silicon infiltration process. The results revealed that the incorporation of α-SiC particles increased the degree of uniformity of the microstructure of the diamond/SiC composites. The acoustic mismatch model was used to analyze the samples before and after diamond graphitization to evaluate the interfacial thermal resistance of the composites. The results indicated that the interfacial thermal resistance of the graphitized composites was 11.9 times higher than the interfacial thermal resistance of the un-graphitized composites. Finally, the correlation between the diamond content of the composites and their thermal and mechanical properties was investigated. [ABSTRACT FROM AUTHOR]

Silicon carbide is one of the most important high-performance engineering ceramics. However, SiC ceramics with complex structure and high mechanical performance are difficult to shape, sinter, and process. Additive manufacturing is expected to solve the above problems, but the photosensitive slurry with low solid content leads to high residual Si content and low strength of final components. Here, we presented one novel strategy to prepare high-strength SiC components with complex structure by introducing quasi-spherical diamond powder as the high-density carbon source through vat photopolymerization 3D printing technology and reactive melt infiltration process. The final RB–SiC ceramics exhibited a specific flexural strength of 312.45 ± 18.75 MPa and elastic modulus of 359.16 ± 4.57 GPa, demonstrating one of the highest flexural strength and elastic modules among those reported for 3D-printed SiC composites. Owing to the high mechanical performance and simple fabrication process, this strategy has significant advantages in the manufacturing of structural SiC ceramics. [ABSTRACT FROM AUTHOR]

[Display omitted] • The harmful diamond wire saw silicon powder was leached with HCl to remove Fe. • The optimal conditions for the leaching of Fe from HCl solution were investigated. • The leaching kinetics of Fe was analyzed by heterogeneous and homogeneous model. • The Fe leaching from DWSSP fits the secondary reaction model of homogeneous model. • The work provides an important guide for preparation of high purity silicon. The diamond wire saw silicon powder (DWSSP) is considered to be a harmful to the environment because of finer particles, the large specific surface area and flammability. Removal of Fe impurity is very essential for recovering Si from DWSSP due to the large amount of Fe introduced during the silicon powder generation process. In the study, the thermodynamics of Fe leaching with HCl was analyzed and determined iron was theoretically present as ions in solution. Furthermore, the effects of different concentrations, temperatures and liquid–solid ratios on Fe leaching from HCl were investigated. The leaching rate of Fe reached 98.37% at the optimal parameters (HCl concentration of 12 wt%, leaching temperature of 333 K, liquid–solid ratio of 15 ml/g) with 100 min. The leaching kinetics of Fe in HCl was analyzed by shrinking core model and homogeneous model, respectively. The study indicated the process of leaching Fe from DWSSP conforms to the secondary reaction model of homogeneous model which coincided with the porous structure of DWSSP due to agglomeration. The apparent activation energy required (49.398 kJ/mol) in the first stage is lower than that (57.817 kJ/mol) in the second stage because of the porous structure. In conclusion, this paper provided a suitable way to purify the diamond wire saw silicon powder. This work provides an important guide for the industrial recovery and preparation of high purity silicon from DWSSP by the most environment-friendly and low-cost approach. [ABSTRACT FROM AUTHOR]

The enhanced optical properties of chemical vapor deposited (CVD) diamond have been pursued in academia and industry for many applications. However, the barrier of CVD technology limits the application field of diamond. Herein, the performance of CVD polycrystalline diamond thick films was improved by high-pressure and high-temperature (HPHT) treatment. The microstructures of CVD polycrystalline diamond films before and after HPHT treatments were thoroughly examined using optical microscope, UV–visible and infrared absorption, Raman spectroscopy, scanning electron microscope (SEM) and transmission electron microscope (TEM). It is found that the transparency of the CVD samples at 10 GPa increases dramatically with processing temperatures, from the original opacity to almost full optical transparency. Through spectroscopic and microstructural analyses, the modification mechanism of CVD polycrystalline diamond under HPHT conditions is proposed. The results show that the HPHT treatment can significantly enhance the optical properties of the starting CVD polycrystalline diamond films. [ABSTRACT FROM AUTHOR]

Boron is considered extremely depleted inside Earth's mantle. It is therefore a great challenge to elucidate the prevalence of boron impurity seen in sublithospheric diamonds, especially in identifying the boron source and the mechanism for its incorporation into these enigmatic diamonds. Here, we unveil a pathway for the crystallization of boron-bearing diamonds via redox reactions of carbonates and borides at pressure–temperature conditions relevant to the Earth's lower mantle. We present computational results along with pertinent experimental evidence for a genesis of boron-bearing diamonds via the redox reaction of CaCO 3 and FeB at 22.5 GPa and 2100 K, corresponding to the geological conditions at the top of the lower mantle. The present findings offer a viable mechanism for the formation of boron-bearing diamonds deep inside the Earth's mantle. [ABSTRACT FROM AUTHOR]

Although monocrystalline silicon exhibits promising microstructural properties for enhancing the performance of optical systems, precise and efficient silicon fabrication is still challenging due to its brittleness. In the present work, we demonstrate the ductile machinability of copper-coated silicon by applying elliptical vibration diamond cutting. Firstly, the influence of the copper coating on the ductile machinability of silicon was experimentally investigated by applying ordinary diamond cutting, showing that the critical depth of cut (DOC) for the ductile-to-brittle transition increased from 118 to 418 nm due to the advantages of the copper coating. This provided hydrostatic pressure in the microcutting regime and the compressive force on the subsurface defects to prevent crack propagation. Subsequently, grooving tests on coated and uncoated silicon were performed by applying elliptical vibration cutting (EVC). Due to the small instantaneous uncut chip thickness in each vibration cycle, the critical DOC by EVC for uncoated silicon increased to 459 nm. Applying the favorable copper coating process, the critical DOC by EVC for coated silicon increased to about 988 nm. The ductile machinability of silicon was efficiently improved by combining EVC and the coating process. Furthermore, the influence of vibration amplitude and cutting speed on the ductile machinability of silicon was explored in detail, leading to the optimized machining conditions for the ductile machining of silicon. Finally, based on these fundamental results, ultra-precision microlenses on silicon were efficiently fabricated, which is appropriate for further industrial applications. • 1. Enhanced ductile machinability of silicon by combination of coating and elliptical vibration cutting was verified. • 2. Compared with ordinary diamond cutting of silicon, the critical depth of cut increased from about 100 nm to 1000 nm. • 3. Coating film provides hydrostatic pressure and compressive force on the subsurface defects to prevent crack propagation. [ABSTRACT FROM AUTHOR]

In this study, molybdenum was used as a binder to prepare sintered polycrystalline diamond (PCD) produced by HPHT technology. The effect of molybdenum as a binder on the comprehensive properties of the PCD was investigated at different temperatures. A detailed characterization of the produced materials demonstrates that molybdenum reacted nearly completely with the carbon of the diamond to form a hybrid matrix (Mo/MoC/Mo 2 C). Microstructural images of the composites evidence a homogeneous distribution of the binder phase and a preserved integrity of the constitutive particles. Based on Raman spectroscopy data, the proximity between the coefficients of thermal expansion (Mo/Diamond) helped maintain composites with a high-quality factor. Regarding the variation in experimental conditions, the increase in temperature was conducive to achieving composites with higher microstructural contiguity. From these results, it can be inferred that molybdenum may be a prospective alternative to be employed as a binding phase in producing well-sintered PCDs. [ABSTRACT FROM AUTHOR]

Diamond properties can be tuned by doping and ion-beam irradiation is one of the most powerful techniques to do it in a controlled way, but it also produces damage and other aftereffects. Of particular interest is boron doping which, in moderate concentrations, causes diamond to become a p-type semiconductor and, at higher boron concentrations, a superconductor. Nevertheless, the preparation of superconducting boron-doped diamond by ion implantation is hampered by amorphization and subsequent graphitization after annealing. The aim of this work was to explore the possibility of creating boron-doped diamond superconducting regions and to provide a new perspective on the damage induced in diamond by MeV ion irradiation. Thus, a comprehensive analysis of the damage and eventual recovery of diamond when irradiated with 9 MeV B ions with different fluences has been carried out, combining Raman, photoluminescence, electrical resistivity, X-ray diffraction and Rutherford Backscattering/Ion-channeling. It is found that, as the B fluence increases, carbon migrates to interstitial sites outside of the implantation path and an amorphous fraction increases within the path. For low fluences (∼1015 ions/cm2), annealing at 1000 °C is capable to fully recovering the diamond structure without graphitization. However, for higher fluences (≥5 × 1016 ions/cm2), those required for superconductivity, the recovery is important, but some disorder still remains. For high fluences, annealing at 1200 °C is detrimental for the diamond lattice and graphite traces appear. The incomplete healing of the diamond lattice and the interstitial location of B can explain that optimally doped samples do not exhibit superconductivity. [Display omitted] • For high B fluences, C migrates outward to interstitial sites and induces strain. • Even for high fluences, annealing at 1000 °C allows recovering of diamond lattice. • Annealing at 1200 °C is detrimental and graphite traces appear. • Higher conductivity occurs in boron-doped diamond after 1000 °C annealing. • Remnant disorder and interstitial location of B could hamper superconductivity. [ABSTRACT FROM AUTHOR]

Eclogitic diamond formation can be associated with interactions between subducted slabs and ambient mantle. To gain a better understanding of the extent of chemical exchange between slabs and ambient mantle and the mechanisms of coeval diamond formation, we examined 16 diamonds with eclogitic garnet inclusions from the Koidu kimberlite complex in Sierra Leone (West African Craton). We analyzed the 16 garnet inclusions for major element, trace element and oxygen isotope (δ18O) compositions and their host diamonds for carbon (δ13C) and nitrogen (δ15N) isotope compositions. The garnet inclusions have δ18O values ranging from +5.4 to +12.1‰ (median = +11.3‰) and all but two have δ18O values ≥+9.9‰. Such high δ18O values indicate a link to protoliths that had undergone extensive low-temperature alteration by seawater, which occurs in the uppermost basaltic layer of oceanic crust, prior to subduction. Diamonds hosting the high δ18O garnets have a crustal δ13C signature (−29.6 to −19.4‰) paired with δ15N values (−5.6 to +1.3‰, with one outlier at +9.9‰) implying typically only minor 15N enrichment. This apparent decoupling of δ18O and δ13C from δ15N indicates diamond formation in an eclogitic substrate where garnet oxygen isotope compositions are inherited from altered low-pressure protoliths, diamond carbon is principally derived from biogenic carbonate and organic matter, and diamond nitrogen is variably added by an external, mantle-derived fluid that prompted diamond formation. Of the two remaining garnet inclusions, one has mantle-like δ18O (+5.4‰) and a positive Eu anomaly, suggesting derivation from gabbroic protoliths originally located deep in the oceanic crust where significant alteration by seawater did not occur. Based on mantle-like δ13C (−4.7‰) and δ15N (−6.9‰), the associated diamond formed from mantle-derived fluids/melts. Relative to the other Koidu garnet inclusions, the final garnet has a small majorite component (formation pressure ∼8 GPa), high Mg# (79.0), elevated Cr# (0.90), and low δ18O (+6.3‰), suggesting encapsulation during infiltration of slab-derived melts into surrounding asthenospheric peridotite, associated with a high degree of chemical exchange between slab- and mantle-derived components. [ABSTRACT FROM AUTHOR]

Diamonds are considered ideal additives for improving the wear resistance of cemented carbide materials and thus for extending their service life. However, the poor wettability and thermal stability of diamonds limit their effectiveness. To solve this problem, in this study, microwave-evaporation technology, a low-cost and simple approach, was used to prepare a uniform titanium coating on diamond surface with an optimized diamond-to-titanium-hydride ratio of 5:3 and an optimized holding time of 1 h at 760 °C. The TiC interlayer with needle-rod microstructure was observed. The coating could increase the oxidation weight-loss temperature by 152.7 °C. The different steps of the high-temperature ablation process of Ti-coated diamond were also revealed. Then, Ti-coated diamond/WC-Co-based cemented carbide composites with uniform microstructure, good interfacial bonding, and no thermal burning loss of diamond were prepared using microwave hot-press sintering with a temperature of 1050 °C only and a pressure of 40 MPa, leading to good wear resistance. The wear rate of the composites prepared with Ti-coated diamond was 25.7% lower at room temperature and 50.7% lower at 400 °C than that of the uncoated diamond. This approach minimized the thermal damage to diamond since both Ti-coated diamond and the composites were prepared at low temperatures. [ABSTRACT FROM AUTHOR]

To investigate the influence of the transition layer on diamond nucleation and growth, the TiMoTa multi-alloy interlayers were firstly prepared on WC-6%Co cemented carbide by double glow plasma surface alloying technique, and diamond was then deposited using microwave plasma chemical vapor deposition system. The thickness of the TiMoTa interlayers increased from 1.2 μm to 2.7 μm with the deposition temperature increasing from 800 to 900 °C. Due to the formation of nano-crystalline structure and hard phase, the as-prepared TiMoTa interlayer exhibited high micro-hardness. In the diamond deposition process, the nano-carbide particles preferentially formed at the TiMoTa interlayers can effectively prevent the further diffusion of C, so the surface carbon concentration rapidly accumulates to the critical value required for the nucleation and growth of diamond microcrystals. Finally, a microscale wear-resistant diamond coating with good adhesion was grown on the transition layer, the crack propagation radius of the diamond coating is ∼162 μm, and can reach Hf 2–3 grade. Therefore, our prepared TiMoTa nano-crystalline interlayer provides a new path for the development of a high-quality diamond coating with good adhesion on cemented carbide. [ABSTRACT FROM AUTHOR]

Microwave-induced electric discharge machining (MV-EDM) is an emerging machining method that can be applied to fine machining of metal materials. A feasibility analysis of the application of MV-EDM to sharpen diamond grinding tools was conducted in this study. A multiphysical simulation model for sharpening using MV-EDM was established, and MV-EDM sharpening experiments and measurements were performed to verify the accuracy of the simulation model. It was found that MV-EDM can effectively improve the protrusion height h p and does not result in severe graphitization of diamond grains under appropriate conditions. Under the conditions of a microwave power of 1 kW and a gap scale d of 0.1 mm, the h p of the diamond grain increased to 91 μm with a complete diamond crystal shape and slight graphitization. In addition, it was discovered that the gap scale d and initial protrusion height h 0 had a significant effect on the protrusion height h p and the graphitization of the diamond grains. After verification, the accuracy of the simulation model for calculating the protrusion height of diamond grains was controlled within a range of ±15 μm. The results of this study provide a theoretical basis for the industrial application of MV-EDM to sharpening. [ABSTRACT FROM AUTHOR]

The friction behavior of rough polycrystalline diamond (PCD) surfaces is important in many applications and devices that are required to operate in various harsh environments and it can be argued that a thorough understanding of the friction behavior is essential to the application performance. However, the interplay between electrochemical corrosion, capillary adhesion and friction behavior of PCD in multi-asperity contacts is still poorly understood. In this work, we quantify the interfacial capillary adhesion at contact interfaces and its effect on the friction response, between a colloidal microsphere and rough PCD films before and after electrochemical corrosion, for water-immersed, low RH, and humid air conditions. For these multi-asperity contacts, we demonstrate how electrochemical corrosion influences the surface hydrophilicity of the PCD surfaces, and how capillary adhesion due to water condensation contributes to the friction force. We estimate the capillary forces from both the microscopic lateral force experiments and elastoplastic boundary element method (BEM) contact calculations. The combined results indicate strongly that the observed increase in friction force on electrochemically-corroded PCD surfaces is governed by enhanced capillary adhesion at the contact interface, as affected by surface hydrophilicity and environmental humidity. [Display omitted] [ABSTRACT FROM AUTHOR]

Surface potential pinning effect is a general rule in semiconductor materials, which can seriously affect the performance of devices. However, the surface potential pinning effect is often overlooked in the literature when studying diamond devices. In our previous work, we experimentally verified that the oxygen terminal with ketone bonds introduces an acceptor surface state, 2.22 eV above valence band maximum (VBM), into bandgap at diamond surface. Here, we further investigated the contact band diagram between metals (Au, Ag, Pt, W, and Pd) with different work function and oxygen terminated diamond using X-ray photoelectron spectroscopy. Results showed that the contact Fermi level was at 2.38 eV, 2.33 eV, 2.32 eV, 2.28 eV, and 2.29 eV above VBM, respectively. In addition, the similar symmetrical photocurrent-voltage characteristics under positive and negative bias were observed between Au–Ag and Ag–Pt electrodes deposited on the same oxygen terminated diamond plate. And the surface energy band can be restored to the similar level after destroying by hydrogen plasma or polishing. All the data above could be drawn a conclusion that the oxygen-terminal can pin the Schottky barrier height. We believe that the results obtained herein will help in the design and theoretical analysis of diamond Schottky devices. [Display omitted] [ABSTRACT FROM AUTHOR]

Diamond/CeF 3 composite film (DCCF) and diamond/CeF 3 /LiF composite film (DCLCF) electroluminescent(EL)devices were deposited on n-type heavy-doped silicon substrates by using microwave plasma chemical vapor deposition system (MPCVD) and vacuum electron beam vapor deposition system (EBVD). A series of corresponding tests characterized the composition, microstructure, and EL characteristics of the devices. The experimental results show that the LiF layer can effectively enhance the blue light emission intensity of the composite film device. Blue light emission can be observed in the two types of devices when the forward bias is applied, and the EL spectra of both devices show a strong wide peak at 440 nm. Meanwhile there is no significant difference in the maximum luminous intensity between them. However, when the reverse bias voltage is applied to the two devices, it is found that DCCF device hardly observes visible light emission, while the blue light emission of DCLCF device is very strong. And the EL spectrum of DCLCF device still shows a strong wide peak at 440 nm, and the blue light emission can reach the maximum at 350 V reverse bias voltage. Its maximum luminous intensity is 3.5 times that of DCCF devices, and its brightness can reach 35 cd/m2. [Display omitted] [ABSTRACT FROM AUTHOR]

Diamond wire sawing is one of the key technologies for wafering in the semiconductor industry. The transverse vibration of the wire during sawing will generate additional displacement that not only reduces the as-cut wafer quality but increases the critical adhesion gap between the wires, which is an important factor limiting the development of diamond wire slicing technology toward narrower kerf loss and thinner as-cut wafer. The vibration measurement of the diamond wire provides an indispensable test basis for its vibration control. Therefore, a machine vision-based transverse vibration measurement method of diamond wire is developed in this paper. The approximate edge position of the wire in the image midline is obtained to crop the region of interest in the image by using the maximum continuous same-directional pixel gradient algorithm and thus reduce the computing time. The wire edges in the image are accurately extracted by an adaptive image segmentation method proposed based on the image histogram. According to the surface topography characteristics of diamond wire, a feature extraction algorithm based on the multiple inward line fitting using the least square method is proposed, which can effectively detect the position of the inner diameter boundary of the diamond wire. Accordingly, the equation of the central axis of the wire in the image is obtained to realize the transverse vibration detection of the diamond wire. To conclude, a diamond wire vibration measurement experiment is conducted and the machine vision detection results are compared with the vibration displacement measured by the accelerometer at the same position of the wire end. The results show that the measurement error of the machine vision vibration inspection is generally small for the different types of diamond wires and the different frequencies of the wire transverse vibration, which means that the measurement method proposed in this paper has good accuracy, and applicability, and robustness. • An adaptive image segmentation method based on image histogram is presented to extract outer contour edges of diamond wire. • A feature extraction algorithm based on multiple inward line fitting is proposed to detect diamond wire inner boundaries. • A machine vision-based vibration measurement method of wire vibration with good accuracy, applicability, and robustness is developed. [ABSTRACT FROM AUTHOR]

Diamond possesses a unique combination of excellent optical, thermal, and mechanical properties, and is therefore an ideal transparent ceramic material for harsh and extreme environments. Due to its important applications in technology, transparent diamond ceramic (TDC) has been explored and prepared by chemical vapor deposition (CVD) or direct conversions of non-diamond carbon precursors at high pressure and high temperature (HPHT), but the preparation of large-size TDC with high mechanical strength remains a challenge. Here, we report for the first time, a transparent polycrystalline diamond ceramic from diamond powder with a transmittance of ∼60 % at wavelengths of 400–1600 nm. The analyses of phase composition, residual stress and microstructure evolution of the sintered samples with different sintering conditions indicate that compression at high temperatures (>2000 ⁰C) facilitates the deformation of diamond grains, allowing for densification and diamond-diamond bonding formation. The sintering pressure of the diamond powders with an optimized particle size distribution was dramatically reduced from 16 GPa to 10 GPa. Our results, based on successfully preparing centimeter-sized TDC, set the standard and the precedent for the large-scale preparation of larger TDC in proximity to industrial conditions. [ABSTRACT FROM AUTHOR]

An application of an ultra-short femto-second (fs) pulsed laser (30 fs , 800 nm, 1 kHz) radiation under a simultaneously varied laser fluence (0.6, 1.2 and 1.8 J/cm2) and number of pulses (2000–32,000 pulses per irradiation site) to process diamond has been investigated to determine an optimal conversion of the diamond's tetrahedral sp 3 phase into an aromatic sp 2 phase with a high degree of crystallinity and without a formation of an sp 2 olefinic fraction, thermal damage or an irradiation-induced surface cracking. The highest sp 2 aromatic crystallinity and the most significant sp 3-to- sp 2 conversion efficiency in diamond was attained at 1.2 J/cm2 with 32,000 pulses. The sp 3-to- sp 2 phase transition was marked by a formation of a metastable carbon in the sp 1 hybridisation (carbyne), evidenced by the characteristic Raman mode at ca. 2065 cm−1. Inclusions of covalently bound carbonyl (-C O) at ca. 1705 cm−1 were also observed on diamond under lower irradiation doses. Both the sp 1 and carbonyl contributions resolved gradually as irradiation dose increased. Well-defined laser-induced periodic surface structures (LIPSS) (aka. nano-ripples) with a high spatial frequency distribution and periodicity of around 100 nm were observed forming in the irradiated regions on diamond owing to the interaction of the laser pulse with the surface plasmons; an ordered and homogeneous formation of LIPSS structures has been observed at 1.2 J/cm2 with 8000 pulses. The impact and implications of these findings on the design and development of future ' all-carbon ' devices by means of a direct non-ablative fs laser processing of diamond are discussed. [Display omitted] [ABSTRACT FROM AUTHOR]

Negatively charged Silicon-vacancy (SiV-) centers in diamond have great potential for optical sensing and bio-imaging applications. Therefore,developing a large-scale and cost-effective way of fabrication of SiV- centers is of great importance to promote their applications. Here, we report a method for large-scale fabrication of SiV- centers in a diamond membrane by using MeV Helium ion implantation. The diamond membrane is highly flexible with a thickness of 10 μ m, made from a CVD diamond-on-Si wafer. By implanting the Helium ions on the nucleation side of the membrane followed by thermal annealing, we demonstrate the fabrication of a sub-micron thick SiV- layer in the surface region. Despite the polycrystalline structure of the diamond membrane, the SiV- centers exhibit a fluorescence lifetime of 1.08 ns, comparable to the SiV- centers fabricated in single crystal diamonds. By using a focused ion beam and varying the ion fluence, we demonstrate patterning of the SiV- centers of different densities. Due to the wafer-size and high flexibility of the diamond membrane and a good emission intensity of the SiV- centers, our method has great potential for making large-scale SiV- based diamond devices for applications such as bio-imaging or sensing. [Display omitted] [ABSTRACT FROM AUTHOR]