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In this study, a type of high-entropy boride (HEB) ceramics ((Ti0.2Zr0.2Nba0.2Hfa0.2Taa0.2)B2) with ∼2vol% oxides and ∼1 vol% porosity was successfully consolidated by spark plasma sintering at 2000°C under a uniaxial load of 50 MPa for 10 min, using self-synthesized high entropy diboride powders from a boro/carbothermal reduction approach. The residual oxides were determined to be m-(Hf,Zr)O2, which were incorporated with minor amounts of boron and carbon. Elastic modulus, Vickers hardness and fracture toughness of HEBs at room temperature were 508.5 GPa, 17.7 ± 0.4 GPa and 4.2 ± 0.2 MPa m1/2, respectively. The as-obtained ceramics possessed excellent flexural strength, particularly at high temperatures. The four-point flexural strengths of HEBs at room temperature, 1600, and 1800°C are 400.4 ± 47.0, 695.9 ± 55.9, and 751.6 ± 23.2 MPa, respectively. Postmortem analysis was conducted on HEB fractured at 1800°C, in the region near their tensile and fracture surfaces, and microstructure observations show that limited dislocation lines were present adjacent to the crack front and edge of the pore, without noticing any trace for dislocation motions. It is the first report on the high-temperature strength of high-entropy diboride ceramics and the strengthening mechanism at high temperatures was also discussed.

Tailoring physical properties in conductive ceramics is difficult, which is dominated by the continuous ceramic matrix. In this study, tunable anisotropic physical and mechanical properties in conductive ceramics were successfully realized by incorporating hexagonal boron nitride (hBN) flakes in their matrices. Two conductive TiB2-AlN-hBN ceramics (TAB) with different hBN contents were fabricated by spark plasma sintering using powder mixtures containing TiN, Al, boron and hBN. Perpendicular to the load direction, flexural strength, fracture toughness, electrical conductivity and thermal conductivity of TiB2-AlN-60 vol% hBN composites at room temperature were 151 ± 6.34 MPa, 2.62 ± 0.31 MPa m1/2, 5.3 × 105S m−1and 77.87 W m−1K−1. Whilst electrical conductivity and thermal conductivity decreased to 2.0 × 105S m−1and 32.25 W m−1K−1at the direction parallel to the load. These differences were created just by incorporating small amounts of extra aligned hBN flakes in the conductive matrix, providing new opportunities to material selection and design.

There is a strength and fracture toughness tradeoff in nanoceramic composite. The strength varies reciprocally with the grain size whereas the toughness contributed by compressive residual stress increases with the dimension of the second phase. In this work, a novel duplex microstructure with reinforced clusters composing of nanosized grains was proposed and validated using a model system of B 4 C-TiB 2 ceramics densified by carbide boronizing. As-obtained ceramics exhibit excellent combined mechanical properties at room temperature, including Vickers hardness, Young's modulus, flexural strength and fracture toughness (by surface crack in flexure method) of 32.1 ± 2.7 GPa, 506.9 ± 2.0 GPa,1175 ± 71 MPa and 5.1 ± 0.4 MPa m0.5, respectively. Both strength and toughness are at least ∼30 % higher than the counterparts with similar composition but homogenously distributed TiB 2 grains. Graphite onion was confirmed to be an intermediate product during reactive sintering, it facilitated the grain pullout during fracture and retained the nanometric TiB 2 grain in the cluster, both of which also contribute the toughening and strengthening mechanisms in the B 4 C-TiB 2 ceramics. [ABSTRACT FROM AUTHOR]

ZrB 2 ceramics with various hexagonal BN (h BN) additions up to 37 vol% were reactively densified by spark plasma sintering using powder mixtures containing ZrB 2 , ZrN and boron. ZrN-boron based additives effectively promoted the densification process, ZrB 2 ceramics reached >99 % relative density at 2000 °C and an applied pressure of 60 MPa with only 5 vol% in-situ formed h BN, whereas the relative density of pure ZrB 2 was only 91.2 % at the same conditions. Increasing the h BN contents, the morphology of h BN grains gradually changed from quasi-spherical to flake dominated, which has substantial influence on their mechanical properties. In-situ ZrB 2 -10 vol% h BN ceramics demonstrated high flexural strength of 597 ± 22 MPa, relatively low Young's modulus of 406 GPa and good machinability, especially for the impressively large strain to failure (1.47 × 10−3) which is superior to most of their counterparts in the ZrB 2 based particulate reinforced ceramics. [ABSTRACT FROM AUTHOR]

Nature is a perfect designer in fabricating biomaterials with well-defined and hierarchical nanostructures. Here we report a biomineralization-inspired approach for preparing hierarchical ZnO structure with high UV-light efficiency. The results show that biomacromolecules play an important role on controlling growth and assembly of ZnO nanostructures. It is found that the biomacromolecules favoring the isotropic growth of ZnO at the high concentration.

ZnO-based ceramic was densified at low temperature by using PSP as binder. The results showed that phenolic resin filled in the ZnO grain boundary layer. The sample has a well hardness of 0.8 GPa and bending strength of 78 MPa. The effect of temperature on the microstructure and mechanical properties was also investigated. It was found that the samples sintered at 300 °C showed higher density and better mechanical properties.

The technique of combustion reaction and quick pressing was adopted to prepare dense nanocrystalline ceramics. The densification process of magnesia compact with a particle size of 100 nm was investigated, under the applied pressure of up to 170 MPa, and the temperature of 1740–2080 K with ultra-high heating rate of above 1700 K/min. As a result, pure magnesia ceramics with a relative density of 98.8% and an average grain size of 120 nm was obtained at 1740 K and 170 MPa, while the ones with decreased relative density and increased grain size were produced under the increasing temperature and the identical pressure conditions. The results indicated that grain growth of the nanocrystalline magnesia was effectively restrained by the combined effect of the ultra-high heating rate and the high pressure. Moreover, under the particular sintering conditions, there existed an appropriate temperature range for the preparation of dense nanocrystalline magnesia, and the excessive temperature would not only exaggerate grain growth but also impede densification.

Recently work shown that an imperfection interface can be deduced by a fast sintering, which termed as Self-propagating High-temperature Synthesis plus Quick Pressing (SHS/QP). In order to investigate the effect of imperfection interface on the transport properties of function ceramics, the SHS/QP was applied to fabricate permittivity BaTiO3 in this article. It was found that this ultra-fast sintering method could not only lead to a broaden-amorphous grain boundary but also semi-conductive grain body simultaneously. It is interesting that the new rapid route can result in the giant permittivity of BaTiO3.

Reliability of indentation method in carbon nanotube reinforced ceramics had been proposed in some works, especially of indentation toughness. In this work the traditional indentation hardness of the Multi-wall carbon Nanotube reinforced alumina composites was studied. It is found that the Vickers hardness and nanoindentation hardness of MWNT reinforced alumina fabricated by SPS decreased from about 20GPa to 16GPa at a critical load force about 1kg. While pure alumina showed a Vickers hardness of 20.6GPa in the whole load force range. When the load force or displacement into surface increasing, continuous recorded hardness, contact stiffness and modulus of the MWNT reinforced alumina showed quite different behavior compared with the pure alumina, especially at middle period of indentation. It was believed that different properties in vertical and horizontal directions of the MWNT were the key. MWNT was compressed and deformed as a soften component in the whole indentation processing. And tensile stress caused by MWNT in composite became significant until an enough strain attained and decreased when a critical stress was over. The results mean the definition of hardness or similar ones seemed need deep description in this type of material.

Hierarchical ZrO2 nanorods have recently received considerable attention due to their special physical and chemical properties. However, traditional preparation methods are involved in expensive equipment, complicated process and high production cost. Here we report a simple hydrothermal approach to prepare hierarchical ZrO2 nanorod. The results show that as-synthesized products are composed of many nanorods with 80~150 nm in diameter and 15~20 μm in length. After annealing, the final product was involved into hierarchical monoclinic ZrO2 (m-ZrO2) nanorods, namely, the big nanorod was made up of many small nanorods with 20~30 nm in diameter and 300~500 nm in length. The possible formation mechanism was proposed based on a series of chemical reactions and the natural properties of zirconium.

Materials with hierarchical porosity and structures have been heavily involved in newly developed energy storage and conversion systems. Because of meticulous design and ingenious hierarchical structuration of porosities through the mimicking of natural systems, hierarchically structured porous materials can provide large surface areas for reaction, interfacial transport, or dispersion of active sites at different length scales of pores and shorten diffusion paths or reduce diffusion effect. By the incorporation of macroporosity in materials, light harvesting can be enhanced, showing the importance of macrochannels in light related systems such as photocatalysis and photovoltaics. A state‐of‐the‐art review of the applications of hierarchically structured porous materials in energy conversion and storage is presented. Their involvement in energy conversion such as in photosynthesis, photocatalytic H2production, photocatalysis, or in dye sensitized solar cells (DSSCs) and fuel cells (FCs) is discussed. Energy storage technologies such as Li‐ions batteries, supercapacitors, hydrogen storage, and solar thermal storage developed based on hierarchically porous materials are then discussed. The links between the hierarchically porous structures and their performances in energy conversion and storage presented can promote the design of the novel structures with advanced properties.

Phytoremediation is the use of vegetation for in situ treatment of contaminated soils, sediments, and water. It is best applied at sites with shallow contamination of metal pollutants. The term “assisted phytoextraction” usually refers to the process of applying a chemical additive to contaminated soil in order to increase the metal uptake by crop plants. In the process of phytoremediation, applying plant growth regulator can promote phytoextraction effects. This paper reviewed the effect of the plant growth regulator for the biological growth, plant transpiration and heavy metal stress. the increase in metal accumulation in upper parts of plant could be related to both the role of PGRs in the enhancement of plant resistance to stress (as toxic metals) and the increase in transpiration rate, i.e. flux of water-soluble soil components and contaminants by the regulation of stomatal opening.

The ZrC oxidization mechanism in air was carefully investigated by the phase composition and grain morphology through DSC, X-ray diffraction and SEM respectively at different temperature. It was found that the oxidization of ZrC start at about 400°C by oxygen atom entering the interstitial sites to substitute part of Carbon. Zr2O and ZrO2 can be formed at a temperature of about 600°C and 1000°Crespectively. And ZrC will completely transfer to ZrO2 at 1000°C for 5hrs. No obvious grain morphology change was found under 600°C.

Co-doped ZnO nanorods membrane was deposited at glass substrate in a simple chemical water bath. The morphology and crystal structure of the samples were characterized by SEM, TEM and XRD. It is shown that the ZnO rods membrane exhibits an excellent orientation along the c axis. X-ray diffraction study also indicates decrease in the lattice parameter after Co doping. The results of EDS and XPS verify that Co2+ is successfully doped into the lattice of nano ZnO rods. 2at% and 5at% Co doped ZnO rods behave stronger UV emission and weaker visible emission.

A new type of ZnO/Ag micro hybrid material has been fabricated by a facile wet chemical method using citrate as a crystal growth modifier. The morphology and component of ZnO/Ag hybrid material were characterized by SEM and XRD. It is shown that the platelike crystals connect together by means of embedding. The sample is composed of wurtzite ZnO and face-centered cubic Ag. The results of XPS, UV-Vis and PL spectra verify the electron transfer from Ag to ZnO. The photocatalytic test with Rhodamine B (RhB) as a representative dye pollutant shows that the ZnO/Ag hybrid material exhibits an improved photocatalytic activity.

Pulse Current Heating (PCH) process is a new method characteristic with shorter time and lower temperature to the fabrication of materials. In the present paper, the PCH was used to join Cu/Fe. The microstructures of the joined samples were observed by optical microscope, the diffusions of elements near the interfaces were made qualitative and quantitative analyses by Electron Probe Mechanism. Diffusion coefficients of Cu and Fe at PCH and Radiation Heating (RH) joining methods were compared. The results showed that, the transition layer widths were from 5 to 8 μm when the Cu/Fe joined at 750 to 850℃ under 5 MPa pressure with holding times 5 or 10 or 15min. Width of the transition layer increase with the increasing of joining temperature and the extension of holding time. The initial interface will move from the Cu side to the Fe one due to the Kirkendall effect. The diffusion coefficients both of Cu and Fe to PCH joining were larger by three orders of magnitude than those of RH joining. The differences between the two methods were analyzed from dynamics and thermodynamics.

The addition of h- BN to a polycrystalline Si3N4 was to increase the fracture toughness and other mechanical properties such as flexural strength and hardness of the material. The hot pressed samples were prepared from the mixture of α-Si3N4, AlN, MgO and h-BN. The composite contained from 0 to 2 wt.% BN powder with sintering aids (9% AlN + 3% MgO). The transparency, mechanical properties and microstructure of hot pressed polycrystalline Si3N4-BN composite materials were investigated by UV/VIS spectrophotometer, scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. The transparency decreased with increasing the content of h-BN into Si3N4.

Ca-α-sialons with low oxygen content were fabricated at 1800°C by hot pressing. The phase and microstructure were characterized by XRD and SEM. The calculated lattice parameter reveals that 20~30% Ca2+ ions still exist in the grain boundary phase of Ca-α′. A large amount of Ca-containing liquid phase efficiently promotes the anisotropic growth of α′ grains in Ca-rich composition. Reinforced only by elongated α′ grains, the fracture toughness of Ca-α′ can reach 4.96 MPa•m1/2.

Nano-technology is a super microscopic technology to deal with the structures of 100 nm or smaller. This technology also involves the developing of TiO2 materials or TiO2 devices within that size. The aim of the present paper is to synthesize the silver doped nano-TiO2 by Sonochemistry method and to evaluate the effect of different percentages (0.2-1.5%) of silver load on TiO2 in the algae inactivation, The sample were characterized by using different techniques as XPS, TEM, SEM. Photo-catalytic activity of Silver doped TiO2 were evaluated through the inactivation of red tide (Cochlodinium) using UV-irradiation (315-400nm). The best result was found with silver doped TiO2.

La doped ZnO nanorods were synthesized via solvothermal technique using Zn(AC)2 and La(NO3)3 as starting materials. The products were characterized by X-ray diffraction (XRD), field scanning electron microscopy (FESEM) equipped with an energy dispersion X–ray (EDX) spectrometer, photoluminescence spectroscopy and UV-vis spectroscopy. The results of XRD in combination with EDS indicated that La was successful doped in ZnO. The obtained La doped ZnO sample exhibited nanorod like morphology and the diameter was about 30 nm. The photocatalytic property of La doped ZnO was evaluated by the variation of the concentration of RhB.

Flowerlike bicephalous titanium diboride (TiB2) nanowhisker clusters were fabricated by planetary ball-milling. The pure cleavage theory and crack growth mechanism were used to explain the formation process. The high-resolution transmission electron microscopy and nano electronic beam diffraction show that TiB2 superhard material always has a cleavage plane along the direction of [0001] zone axe and [10 0] zone axe because of its big interplane distance, weak bonding force between planes and low index directions. The flowerlike bicephalous TiB2 nanowhisker can be gained after repeated cleavage under high strains. The discovery could open a new path to fabricate C32 type superhard ceramic nanowhiskers.

Two different kinds of mullite precursors with composition 3Al2O3•2SiO2 (3:2) were prepared by conventional drying ethanol solution and spray-drying aqueous solution of aluminum nitrate nanohydrate and tetraethoxysilane, respectively. The results of scanning electron microscope (SEM) indicate that one powder consists of irregular particles with size of 1-10μm, the other powder is made of inhomogeneously sized hollow spherical particles with mean size of 0.5-5μm. The TG-DTA curves indicate the hollow spherical particles are unfavorable to eliminate the decomposed products. After the precursors were sintered by Spark Plasma Sintering at 1450°C for 10min, the microstructures of the former are made of fine equiaxed grains with sizes of around 0.5μm, the latter consist of elongated grains distributed in the matrix of fine grains with imhomogenous size of 0.5~10μm due to the liquid phase forming. The different microstructures lead to the former sintered body is transparent, while, the sample from spray-drying is opaque.

The densification behavior and mechanical properties of B4C by SPS at 1900°C for 2 min with additions of Al2O3 up to 10 wt.% were investigated. When the additional of 10 wt.%, the relative density was 99% and the hardness went to 33GPa. Sinterability was greatly improved by the addition of a small amount of Al2O3, and the SPS technology with high hearing rate is particularly attractive for prepare of poorly sinterable materials. The improvement was attributed to the enhanced mobility of elements through the Al2O3 near the melting temperature. As a result of this improvement in the density, mechanical properties, such as hardness, fracture toughness, increased remarkably.

The equiatomic multicomponent CoCrFeNiCuAl high-entropy alloy powder was synthesized by mechanical alloying. The effects of milling time and heat treatment on the structure and morphology of the ball milled alloy were investigated. Single BCC solid solution structure appears when the alloy is ball milled more than 30h. The 60h ball milled alloy powder shows a mean particle size of 3 μm, which is actually hard agglomerations of nanosized crystals with crystalline size less than 10nm. The 60h ball milled alloy exhibits good chemical homogeneity. The single BCC solid solution structure transforms to a BCC and a FCC phases when annealled at 600°C for 1h, which can be attributed to the supersaturatable solid solution formation during the mechanical alloying process.

ZrC fine powder has been prepared by self-propagating high-temperature synthesis (SHS) using exothermic reaction of ZrO2-C-Mg system. By theoretical calculating, the adiabatic temperature (Tad) for the system is about 2235K enough to react as SHS process. The Tad observed during experiment is 1850K. The results show that high pure ZrC powder is obtained with appropriate Mg contents. The scanning electron micrograph shows that the average size of ZrC particles is about 2μm.

TiO2/TiB2 heterostructures were successfully synthesized by a facile hydrothermal approach in an aqueous solution of hydrogen peroxide (H2O2). The influence of H2O2 on TiB2-based materials was systematically investigated using X-ray diffraction, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results show that TiB2 is prone to oxidize in the presence of H2O2. TiO2/TiB2 heterostructure which high-density anatase-TiO2 stand on the surface can be gained in the presence of H2O2 solvent and the final composition can be controlled by the temperature and time. The investigation may provide a path to further understand the chemical property of TiB2-based materials and synthesis method of heterostructure.

In this text, 5083 aluminum alloy was prepared with the method of the liquid nitrogen cryogenic milling (cryomilling). The microstructure,microstructural evolution and thermal stability of sample powder was investigated by XRD,SEM and DSC. The experimental results show that the particles size of 5083 aluminum alloy power during cryomilling was gradually reduced; milling time and milling speed are the main factors of affected alloy structure and performance, and high speed cryomilling could result in more uniform nanometer grains. The microstructure of the cryomilling 5083 aluminum alloy for 5 hours is micron-sized agglomerates with an average grain size of 45 nm.

SnO2 nanocrystals with various morphologies were synthesized via a hydrothermal method assisting by the surfactant CTAB. The morphologies of the products were significantly dependent on the synthesis conditions. The products were characterized by X-ray diffraction (XRD) and field scanning electron microscopy (FESEM).The results showed products SnO2 nanoparticles and spheres like structure assembled with nanocones were obtained by varying the dosage of CTAB and the concentration of NaOH. The forming process of SnO2 sphere like structure was discussed and the proposed mechanism was put forward in this work.

Within a very short heating period, fine mullite powder with practicle size below 1µm was obtained in a novel synthesis system, a self-propagating high-temperature synthesis (SHS) chemical furnace, from which the tremendous heating derived. The combustion reactants consisting of Ni, Al and TiC were chosen as a chemical furnace in this system to supply the heat, calcining temperature was increased at a heating rate of 1350K/min in the heating process, till the maximum temperature (1350℃). The rapid mullitization process was performed within 1 min, microstructure analysis indicated that small mullite grains (<50nm) were crystallized, fine mullite particles (<1µm) with narrow particle size distribution, favorable activity for sintering were derived. And significant grain growth was observed in mullite powder, when the combustion reactants consisting of Ni, Al and <30 mol.% TiC.

Dense nanocrystalline Y2O3 ceramics without grain growth have been successfully obtained by a new method, which is based on the self-propagating high temperature synthesis and quick pressing. A suitable self-propagating system with a maximum combustion temperature of 1350 ℃ and a heating rate of 1300 ℃/min was chosen as a chemical furnace to supply the heat to densify nanocrystalline Y2O3. Dense samples without grain growth were obtained when the applied pressure was 120 MPa.

The Indium Tin Oxide(ITO) is known as a poorly sinterable material. The Spark Plasma Sintering(SPS) and the hot-pressing sintering(HP) were used to fabricate Indium Tin Oxide Ceramics from ITO nanoparticles. The maximum bulk density of 7.02 g/cm2(relative density; 98.2% TD)was obtained when sintered in Ar at 1000oC for 1min by SPS sintering. While the bulk density of 7.08 g/cm2(relative density; 99% TD) was obtained when sintered in Ar at 1050 oC for 4h by HP sintering.

Mullite-based FeCr multifunctional composites were prepared by reducing (Fe, Cr)-doped mullite solid solution powders with different Cr/Fe ratio and successively hot pressing. Structural characterization revealed that the dispersion of intragranular FeCr alloy nanoparticles and intergranular iron grains in mullite matrix was obtained in nanocomposite powders. Dense mullite-FeCr composites were fabricated from nanocomposite powders by sintering at 1650 °C. The microstructures, mechanical and ferromagnetic properties of composites were strongly affected by the Cr/Fe ratio in initial solid solutions.

Ultra-fine zirconium diboride (ZrB2) powders have been synthesized by borothermal reduction reaction, using zirconium oxychloride (ZrOCl2•8H2O) as the precursors of zirconia. The thermodynamic variation in the amorphous ZrO2-B system was studied by thermogravimetric and differential thermal analysis (TG-DTA). The precursors containing amorphous ZrO2 and B were heat-treated under a high heating rate. It is shown that the borothermal reaction can be completed at a relatively low temperature (~950 ºC) and short duration (~5 min) under a heating rate of 200 ºC/min. The synthesized powders have an average crystalline size of 300 nm with oxygen content less than 2.62 wt%.

In this paper, a carbothermal reduction and nitridation (CRN) synthesis for cubic aluminum oxynitride (γ-AlON) powders is reported. The CRN reaction was conducted via a two-step synthesis procedure at a heating rate of 100 °C/min. In the first step, the mixture of fine γ-Al2O3 and soluble starch was annealed at 1550~1580 °C for different duration. It is found that the mixture of α-Al2O3 and AlN with an appropriate ratio can be obtained by CRN reaction. The content of AlN in mixture is closely related with the reaction condition. In the second step, the as-received mixture of α-Al2O3 and AlN was heat-treated at 1700 °C for 10 min. The single phase γ-AlON powders with particle size less than 3 µm were obtained.

Here we have prepared B4C/CNTs composites using the spark-plasma sintering (SPS) method. Mechanical property measurements reveal obvious enhancement confirming the fabrication of true B4C/CNTs composite materials with improved toughness properties.The addition of 1wt% CNTs in the B4C increased the fracture toughness by about 1.6 times from 2.5 to 4 MPa.m1/2 because the CNTs presented at the B4C grain boundaries, made the length of cracks shorten.

Carbon nanotubes reinforced alumina was fabricated by spark plasma sintering method. When adding 0.2wt% nanotubes, the fracture toughness of the composites prepared increases 19% compared with the pure alumina ceramics. The effect of sintering schedule on microstructure and mechanical properties is investigated systematically. Microstructure studies reveal that at high sintering temperature, the nanotubes tend to gather in the gaps surrounded by three or more grains in a flocculent state, which leads to poor mechanical properties. Raman spectrum indicates that long sintering duration may cause serious nanotubes destruction and lower the mechanical properties.

Based on the nitridation reaction of aluminum with boron nitride (BN), aluminum nitride (AlN) matrix composites were fabricated by reaction synthesis technique. The effect of the amount of Al on the microstructure and properties was investigated. The bending strength, thermal conductivity and dielectric constant increase with the content of aluminum. A heat-treatment schedule was performed to investigate the effect of the microstructure on the properties. The results showed that the heat-treatment leads to the grain growth and thermal conductivity increase with the grain growth.

Combustion synthesis of titanium diboride(TiB2) from titanium(Ti) and boron(B) powders was studied by theoretical calculation and experimental analysis. In high temperature range or in low temperature range, the calculated activation energies are 140KJ/mol or 355KJ/mol respectively, which is described by a change from dissolution-precipitation controlled process to diffusion-controlled process. With the increase of particle size of the raw materials, combustion temperature and propagating rate will both reduce. The propagating rate decreases with the addition of diluents. Further increase of diluents may result in a stop of the combustion wave halfway or even a failure of ignition.

Hybridization is a promising method for core/shell particles by a mechanical shock process involving dry blending and dry impact blending. In this paper, hybridization was used to prepare TiB2/Ni ceramics/metal and TiB2/Al2O3 ceramics/ceramics core/shell particles. The mechanism of the formation and the features of the core/shell particles were analyzed. The nano- Al2O3 particles can be coated on the surface of micron TiB2 particles directly by hybridization, The sub-micron Al2O3 particles can be coated on the surface of micron TiB2 particles, only with the introducing of PE-wax as transition layer. The mechanical properties of cermet sintered from TiB2/Ni core/shell ceramics/metal particles were compared with that from TiB2/Ni blended particles.

The combustion synthesis and densification process for titanium diboride and iron layered materials in the process of Self-propagating high-temperature synthesis of titanium diboride, variation of the initial temperature, amount of diluent and particle size of raw materials had effect on the adiabatic temperature, fraction of melted product and propagation rate of the combustion process, were studied by theoretical calculation and experimental analysis. The result showed that divided by a combustion temperature 3050K, either in the high temperature range or in the low temperature range, the calculated process activation energies were 140 KJ/mol or 355 KJ/mol respectively, which revealed two different reaction process mechanisms. Interfacial bonding between TiB2+Fe cermet and Fe substrate was analyzed by EPMA, which showed interfacial bonding of two-layered product was obtained by the dissolution and the diffusion of Ti in the Fe substrate and joining of Fe binder with Fe substrate. The fractures of joints took place in the TiB2+Fe cermet layer rather than at the interface.

Translucent AlN ceramics were fabricated using spark plasma sintering (SPS) technique with 3wt% CaF2 as sintering additive. The samples achieved 52.4% maximum transmittance in medium IR region after 10 min holding time by spark plasma sintering at 1800°C and 30 MPa pressure in N2. The results from XRD, SEM, TEM and EDX showed that the sintered bodies were densely compacted and highly pure with fine grain size and uniform microstructures. No secondary phases were observed at the grain boundaries and triple grain junctions, which guaranteed good optical property of the sintered bodies.

A novel approach was developed to prepare Ni-coated TiB2 cermet. Fine Ni particles with mean particle size of about 80 nm were impacted onto coarse TiB2 particles having a mean size of about 5 μm to form Ni-coated TiB2 powder by Hybridization. The conventional blended TiB2-Ni powder, as well as Ni-coated TiB2 powder, was sintered by hot pressing (HP) method and Spark Plasma Sintering (SPS) method. Compared with the conventional blended TiB2-Ni cermet, particle features and mechanical properties of the Ni-coated TiB2 cermet were investigated. The microstructure analysis reveals that the thickness of Ni film is around 4 nm. It is concluded that the mechanical properties of Ni-coated TiB2 cermet are superior to the blended TiB2-Ni cermet.

MoSi2 is one of the few intermetallics to have potential for further systems. However, the use of MoSi2 has been hindered due to the brittle nature of the material at low temperatures, inadequate creep resistance at high temperatures, accelerated (pest) oxidation at temperatures between 450~ 550°C. In this investigation Mo(Al,Si2)/Ti3SiC2 composites has been prepared by reaction hot-pressing from Mo, Si, SiC, Ti, Al powder mixture under different temperatures. XRD results show that the main products are Mo(Si,Al)2 and Ti3SiC2. Part of TiC and SiC also appeared at low treating temperature. With the treating temperature increasing SiC disappeared. No evidence show lattice change of Mo(Si,Al)2. It must be the results of sufficient Al added. The electrical conductivity properties were also investigated. Samples treating under different temperatures showed different changes. Samples under high treating temperature showed a near linear change ranging from 27~800°C and Samples under low treating temperature showed a nonlinear change.

Radix salvia miltiorrhiza is a commonly used herbal medicine in China, and tanshinone IIA is one of the major active ingredients. Nano Radix salvia miltiorrhiza particles were successfully prepared by high speed centrifugal sheering (HSCS) technology, and the prepared nanoparticles suspension was subsequently spray-dried. The different properties of nano particles and raw powder were systematically studied by laser light scattering granulometric analyzer, TEM, SEM and FTIR. The extractive quantity of tanshinone IIA was determined by high-performance liquid chromatography (HPLC). The results illustrate that raw Radix salvia miltiorrhiza powder can be ultrafinely ground to nanosize within 50min, and the molecular structure of active ingredients doesn’t change after being ground. Furthermore, the active ingredients can dissolve out directly and fully, and the extractive ratio of tanshinone IIA increases 28.6% by HSCS processing. It is valuable to combine nanotechnology and TCM to improve the bioavailability and rapid releasing.

In this paper, we suggest PCH as a method of joining alloys. The temperature distribution in the samples during the joining process was analyzied. From the temperature distribution profiles in PCH joining, it is concluded that PCH for the joining has two advantages: (1) There is a temperature distribution peak along the sample. The contacting surfaces which need high temperature happen to obtain the highest temperature; (2) The parts to be joined at relatively lower temperatures can avoid the damage of heat attack. The optimal joining conditions were discussed. The PCH and HP techniques were compared for the joining of alloys. It was found that the high tensile strength joined structure of alloys can be fabricated by PCH method at lower joining temperature, shorter holding time, and lower pressure, compared with that by HP method. The PCH process was considered to be an eco-friendly process compared with the traditional heat diffusion joining methods.

Mullite-based nanocomposites with embedded FeCr alloy nanoparticles were synthesized by reduction of sol-gel prepared Al5.4(Fe0.8Cr0.2)0.6Si2O13 solid solution in hydrogen. The feature of the formation of FeCr alloy is characterized by XRD analysis. Structural characterization revealed that the intragranular FeCr alloy nanoparticles along with inter-granular iron grains were obtained in as reduced sample. After acid washing, the intergranular metal grains were eliminated. The static magnetic properties of nanocomposite powders were studied using Magnetic Property Measurement System. It is found that part of the intra-granular metal nanoparticles have superparamagnetic behavior at room temperature.

Recently research shows that heterogeneous model is needed to explain some complex combustion behaviors in SHS. However, more heterogeneous details be considered more difficulties will be faced. A micro-heterogeneous & macro-homogeneous model is proposed in this paper based on some previous works for this problem. Combustion compact is divided into lots of little units, which are composed of a large number of small particles. Considering a well-mixed situation, properties of every unit must be almost the same, so the compact can be treated as a macro-homogeneous system on the scale of these little units. During the combustion, every unit will have a heterogeneous properties and change; it can be gotten by a micro-heterogeneous model. Therefore, the micro-heterogeneous characters are connected with the Marco-combustion behaviors. Combustion dynamics of Ti-C-Fe system was studied to certify this model. Results show well consistency with experiments results.

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