Search

This research delves into the design, modeling, and finite element impact analysis of the segmented sandwich composite armor system subjected to impact loading, considering different parameters such as materials to be used, armor height, and armor design configuration. Initial studies were performed to select the ideal model that will provide the best impact resistance at the least weight and with minimal fabrication requirements. Material type, thickness, and overall model configuration were defined during the initial model development period. Once the final design was defined, finite element analysis was performed using 2017 ABAQUS software to observe the performance of the model and to validate the efficiency of the chosen armor. Based on the results from the material selection and thickness validation, the optimal design with the best impact resistance was noted as 1.2 mm thick rectangular segmented silicon carbide tiles, serving as the top layer that covers the three-level gradient core composed of a titanium metal honeycomb frame filled with silicon carbide inserts, and finally a 2 mm thick glass epoxy composite layer made from four laminas in a 0/45/90/-45-degree configuration serving as the last layer of the armor. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Central South University is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Comunicaçõe Geológicas is the property of Laboratorio Nacional de Energia e Geologia, I.P. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The energy levels created in supersaturated n-type silicon substrates with titanium implantation in the attempt to create an intermediate band in their band-gap are studied in detail. Two titanium ion implantation doses (1013cm-2 and 1014cm-2) are studied in this work by conductance transient technique and admittance spectroscopy. Conductance transients have been measured at temperatures of around 100 K. The particular shape of these transients is due to the formation of energy barriers in the conduction band, as a consequence of the band-gap narrowing induced by the high titanium concentration. Moreover, stationary admittance spectroscopy results suggest the existence of different energy level configuration, depending on the local titanium concentration. A continuum energy level band is formed when titanium concentration is over the Mott limit. On the other hand, when titanium concentration is lower than the Mott limit, but much higher than the donor impurity density, a quasi-continuum energy level distribution appears. Finally, a single deep center appears for low titanium concentration. At the n-type substrate, the experimental results obtained by means of thermal admittance spectroscopy at high reverse bias reveal the presence of single levels located at around Ec-425 and Ec-275 meV for implantation doses of 1013cm-2 and 1014cm-2, respectively. At low reverse bias voltage, quasi-continuously distributed energy levels between the minimum of the conduction bands, Ec and Ec-450 meV, are obtained for both doses. Conductance transients detected at low temperatures reveal that the high impurity concentration induces a band gap narrowing which leads to the formation of a barrier in the conduction band. Besides, the relationship between the activation energy and the capture cross section values of all the energy levels fits very well to the Meyer-Neldel rule. As it is known, the Meyer-Neldel rule typically appears in processes involving multiple excitations, like carrier capture and emission in deep levels, and it is generally observed in disordered systems. The obtained Meyer-Neldel energy value, 15.19 meV, is very close to the value obtained in multicrystalline silicon samples contaminated with iron (13.65 meV), meaning that this energy value could be associated to the phonons energy in this kind of substrates. [ABSTRACT FROM AUTHOR]

Titanium oxide can be converted directly to its metallic state. This extraordinary technology is realized in a CaCl2-based molten salt that can extract oxygen ions from the cathode. Several discussions have been exchanged in the field of electrochemistry and metallurgy in the last two decades. Recent papers on titanium refining are overviewed by selecting popular papers, especially those published in this journal, Materials Transactions. Basic and scientific studies on titanium and its refining are briefly analyzed, and some practical applications are introduced in related oxide reductions and the corresponding molten salts. [ABSTRACT FROM AUTHOR]

To understand the physics of double-pulse femtosecond laser ablation of metals, the authors have proposed and implemented a new ablation method for measuring the temporal change in the laser penetration length (LPL). The measurements were performed for titanium and platinum with femtosecond laser pulses with a central wavelength of 810 nm, a repetition rate of 10 Hz, and a pulse duration of 45 fs. The delay between the seed pulse and the ablation pulse was between 0.3 ps and 1 ns for titanium and between 0.3 ps and 30 ns for platinum. A low-fluence (below the ablation threshold) seed pulse and a high-fluence (above the ablation threshold) ablation pulse were used for the measurement. The seed pulse modifies the optical properties of the target surface, and the ablation pulse creates a crater on the modified surface. The LPL after seed-pulse irradiation was estimated by analyzing how the ablation rate depends on the laser fluences. With a delay of 300 ps, at which the ablation rate is the lowest for both titanium and platinum, the LPL for a titanium target was 40% of that for the target without seed-pulse irradiation, while the LPL for a platinum target was almost the same as that for the target without seed-pulse irradiation. The reduced LPL corresponded to suppressed ablation for titanium and platinum with a delay of 300 ps. The suppression ratio η sup (ablation rate with seed pulse divided by ablation rate without seed pulse) for titanium (η sup = 0.5) was less than that for platinum (η sup = 0.8). The LPL measured using the proposed ablation method is a key parameter changed by seed-pulse irradiation. For platinum with a delay exceeding 1 ns, a characteristic increase of LPL was also measured. [ABSTRACT FROM AUTHOR]

Titanium ions are implanted into amorphous SiO2 at two different fluences using pulsed ion implantation, and the resulting samples are annealed. Bulk sensitive soft X-ray absorption spectroscopy of the Ti L2,3 edge reveal strikingly different spectra for the two fluences. Spectral simulations using multiplet crystal field theory show clearly that for low fluence the Ti ions have a local octahedral coordination, while at higher fluence the formation of Ti4+-O tetrahedra dominates. Using O K-edge X-ray absorption and emission, the effect of the Ti states on the valence and conduction bands of the host SiO2 is revealed. With the introduction of Ti tetrahedra, the band gap reduces from about 8 eV to just over 4 eV, due entirely to the Ti 3d conduction band states. These results demonstrate the possibility to obtain Ti-O tetrahedra in silica by Ti ion implantation and a suitable thermal treatment, clarify the mechanism of band gap reduction with Ti doping in SiO2, and demonstrate the sensitivity of L-edge X-ray absorption with a multiplet crystal field theory analysis to the Ti coordination of novel materials. [ABSTRACT FROM AUTHOR]

Wastes from titanium-magnesium production are characterized by a variety of composition, properties and a wide range of applications. As a result of the research on industrial effluents utilization in titanium-magnesium production a technology was proposed that includes the separation of effluents by centrifugation into liquid and solid parts and the demineralization of the liquid part using vacuum evaporation. As a result of laboratory studies, the optimal composition of the building mixture was determined, which can be used to prepare new materials for the construction industry with high strength characteristics. Optimal cement-sand ratio in the charge of building mixture is 1:3, water-cement ratio is 0.4, thickened pulp of industrial wastes contains 100 - 240 g/dm³ of solid part. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to compare the osteoblastic and osteogenic responses to titanium surfaces roughened by 1-step and 2-step acid etching. Materials and Methods: Titanium surfaces created by 1-step (AE1) and 2-step (AE2) acid-etching processes were analyzed using scanning electron microscopy (SEM), atomic force microscopy (AFM), and an optical interferometry (OI). Rat bone marrow-derived osteoblastic cells were cultured on these 2 surfaces. Cell proliferation was evaluated by counting the cells, while gene expression was analyzed using a reverse transcriptase-polymerize chain reaction. The biomechanical establishment of osseointegration was assessed via an in vivo implant push-in test in rat femurs. Additionally, the 2 surfaces were evaluated for their mechanical interlocking capability by a push-out test of titanium rods embedded in a resin block. Results: AFM analysis on a small scale of 5 μm × 5 μm showed that the 2 surfaces were similar in topography, having comparable micron-level roughness. However, larger scale (1000 μm × 1000 μm) SEM and OI analyses revealed that the AE1 surface consisted of supramicron convexity structures ranging from 10 μm to 50 μm in size, while the AE2 was relatively flat. No differences were found between the 2 surfaces in regard to the number of the cells proliferated or the expression of the bone-related genes. The biomechanical fixation of implants at week 2 was 22.2 ± 10.94 N and 25.4 ± 4.56 N for AE1 and AE2, respectively, with no significant difference between the 2 groups. The in vitro push-out values were 26.8 ± 7.85 N and 25.4 ± 8.56 N for AE1 and AE2, respectively, with no significant difference between the 2 groups. Conclusion: The different acid-etching procedures of titanium created similar micron-scale roughness profiles but distinct supramicron roughness characteristics. Osteoblastic function and in vivo osseointegration capacity, however, were not affected by this difference between the surfaces. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this article is to describe a technique that attempts to solve titanium-related problems while affording passive fit. Materials and Methods: The method basically involves the manufacture of a cast titanium framework fitted onto titanium machined abutments. After verifying the passive fit of the framework presoldered to the abutments, Nd-YAG laser welding is completed in the laboratory. Results: The aim of the technique is to secure the following clinical benefits: (1) use of titanium, as it is the best-suited material; (2) use of high-precision machined abutments; (3) laser welding and its advantages; and (4) achievement of passive fit. Conclusion: The technique described is adequate to achieve passive fit in implant prostheses using titanium and laser welding. [ABSTRACT FROM AUTHOR]

Calcium zirconate refractories exhibit a promisingly high corrosion resistance in contact with titanium alloy melts. In the present article, we improved the thermomechanical properties of calcium zirconate based refractories by altering their microstructure and chemical composition. In a full factorial experimental design we investigated the effects of an insitu phase formation, of the addition of coarse grained MgO aggregates as well as the addition of SrCO 3. Based on these factors, the chemical, physical, mechanical and thermomechanical properties as well as the resulting microstructure were thoroughly characterized. Strikingly, the addition of SrCO 3 resulted in significantly improved mechanical properties before and after thermal shock. The improved thermal shock resistance can be attributed to a lower determined thermal expansion coefficient, a homogeneous pore size distribution with a reduced pore size and a better bonding between the matrix and the coarse grained aggregates. [ABSTRACT FROM AUTHOR]

Ti-6Al-4V produced by laser powder bed fusion can achieve mechanical properties similar to its wrought counterpart if an appropriate post-process heat treatment is applied. The response of the material to post-process heat treatment depends on the prior-beta grain size in the as-built condition. The current article illustrates that a reduction in hatch distance can cause coarsening of prior-beta grains due to retained heat that reduces the cooling rate. On the other hand, an increase in scan speed refines prior-beta grains. Unfortunately, an increase in scan speed has to be accompanied by a reduction in hatch distance to prevent an increase in porosity and the potential grain refinement is then cancelled out. The use of a faster scan speed in combination with a smaller hatch distance significantly improves roughness of the top surface. EBSD in combination with reconstruction of prior-beta grains is an effective technique to quantify prior-beta grain size. Furthermore, the use of Rosenthal's equations allows quick calculation of cooling rate that can be used to predict the dependence of prior-beta grain size on process parameters. [ABSTRACT FROM AUTHOR]

A novel approach was developed to fabricate low - oxygen powder metallurgy Ti–6Al–4 V (wt.%) titanium alloy with a highly desirable combination of ultrahigh tensile strength and good ductility. Using clean and unpassivated TiH 2 based powder compact, together with cleaning effect of in-situ dehydrogenation during heating the powder compact resulted in a low oxygen content of 0.26% in final extrusion consolidated alloy. The nature of cleaning effect during sintering was proved to be a reduction reaction of TiO 2 + 4[H] = Ti + 2H 2 O (g). Besides, solution & aging treatment produced a unique composite lamellar microstructure, which mainly consists of fine α platelets and β-transformed structures containing high number density of ultrafine acicular α precipitates. Such composite lamellar microstructure gave rise to extra geometrically necessary dislocations during tensile deformation and brought about significant dislocation hardening together with high global strain. Consequently, this Ti–6Al–4 V alloy exhibited a superior ultimate tensile strength of up to 1320 MPa and meanwhile a high elongation to fracture of not less than 12.5%. [ABSTRACT FROM AUTHOR]

Abstract The main requirements of tungsten materials for structural divertor applications comprise properties like high thermal conductivity, high-temperature strength and stability, high recrystallization temperature, and enough ductility for an operation period of about two years under massive neutron load [ 1 ]. However, the mechanical properties of tungsten commercial products are still one of the main concerns for their use in structural armour applications. With the aim of improving this aspect, two W/Ti based products are presented in this paper: (1) a W-Ti alloy with a Ti solid solution and (2) an UFG microstructure product with TiC dispersed particles; both with the aim of obtaining a suitable fusion armour material with enhanced properties, especially at very high temperatures when pure tungsten suffers strong thermal degradation. It has been reported that strength and recrystallization control can be improved with dispersed TiC particles which inhibits the grain growth. Furthermore, both flexural strength and fracture toughness were twice and even three times higher than the ones observed for our reference pure tungsten produced by the same group and technique, which is, indeed, a great success. However, the intrinsic brittleness of tungsten cannot be enhanced by particle dispersion or solid solution with Ti. On the contrary, intergranular rupture is enhanced even more, and the DBTT is even higher than that of pure W. [ABSTRACT FROM AUTHOR]

The grain refining efficacy of titanium, aluminum, and niobium borides, as well as niobium aluminides, introduced via commercial and lab made master alloys on Al-Si alloys was investigated. Significant grain refinement is achieved via the introduction of these heterogeneous nuclei regardless of their chemistry, stoichiometry of the master alloy, and addition rate. However, the grain refinement is affected by variable such as contact time, as the inoculating particle may sediment or be poisoned, and cooling rate. Specifically, a faster cooling rate generally leads to finer grains due to the lower time for grain growth. In the case of borides, the chemical inoculation efficiency is greatly affected by their thermodynamic stability in molten Al-Si alloys. Conversely, the grain refining potency of properitectic Al3Nb remains unaffected. The underlying grain refining mechanism was finally investigated using current models based on the growth restriction factor Q to simultaneously consider the effect of nucleant potency and alloy chemistry. Among Ti-, Al-, and Nb-based borides with similar particle size and distribution, the latter are the most efficient to grain refine Al-Si alloys. [ABSTRACT FROM AUTHOR]

Abstract The pre-mixed pure Ti and Cr 2 O 3 powder was consolidated by spark plasma sintering (SPS) and hot extrusion to fabricate α-titanium (Ti) materials with oxygen (O) and chromium (Cr) elements by powder metallurgy (PM) process. The Cr 2 O 3 particles were completely decomposed during SPS, and then O and Cr atoms were dissolved in α-Ti matrix. Oxygen atoms were remarkably improved the mechanical strength of PM Ti-O-Cr alloys by their solid solution hardening effect. The Cr solution and Ti 4 Cr precipitates had important roles to obstruct the grains coarsening behavior by the solute drag and Zener pinning effects, respectively. The solid solution strengthening effect by Cr atoms, however, was very limited due to a small Cr solubility of about 0.35 at% in α-Ti phase of Ti-O-Cr alloys. Since Ti 4 Cr precipitates with 10–20 µm diameters were not so fine, they hardly contributed to the precipitation hardening of Ti-O-Cr alloys. [ABSTRACT FROM AUTHOR]

Abstract In this paper, a new method of manufacturing nanostructured titanium (n-Ti) is presented. An effective way of grain refinement and strengthening a material using conventional plastic working is proposed. Microstructured titanium (m-Ti) Grade2 was processed using caliber rolling technology. In this work, the m-Ti billet in the initial state was in the form of a rod with a diameter of 10 mm. This billet was subjected to multi-pass longitudinal cold caliber rolling, during which the transverse section of the rod was gradually reduced. The rolling was carried out in such a way as to accumulate a relatively large plastic deformation in the workpiece. The rolling process resulted in a refinement of the microstructure into a nanostructure. The average grain size of 74 nm and enhanced mechanical properties were obtained. This single-phase Ti Grade2 with a nanostructure exhibits mechanical properties typical for titanium alloys. The results of the research confirmed that the technology used in this work makes it possible to generate a heavy strain enough for the purpose of grain refinement. [ABSTRACT FROM AUTHOR]

The fracture behavior of commercially pure titanium (CP-Ti) processed by accumulative roll bonding (ARB) was investigated in this study. Monolithic and Ti-SiC composite samples were first produced by ARB process and then subjected to uniaxial tensile testing at room temperature. Two different ductile fracture mechanisms including shear dimple rupture and equiaxed dimple rupture were observed in the initial and final ARB cycles, respectively. The difference in the rupture mechanism was attributed to different stress states at the crack tip and different densities of metallurgical defects. A non-uniform distribution of dimple size was obtained for fracture surfaces of the samples processed by a low number of ARB cycles. This was attributed to the heterogeneity of microstructure in the primary ARB cycles. The fracture surface of the samples processed by high ARB cycles represented more uniform dimples. This was attributed to more homogenous microstructure in the final cycles. Moreover, SiC particles showed a major role in fracture of samples, so that they affected the size and depth of the dimples, as well as the number of ARB cycles in which the transmission of the fracture mechanism occurred. [ABSTRACT FROM AUTHOR]

Powder metallurgy (PM) of titanium is a potentially cost-effective alternative to conventional wrought titanium. This article examines both traditional and emerging technologies, including the production of powder, and the sintering, microstructure, and mechanical properties of PM Ti. The production methods of powder are classified into two categories: (1) powder that is produced as the product of extractive metallurgy processes, and (2) powder that is made from Ti sponge, ingot, mill products, or scrap. A new hydrogen-assisted magnesium reduction (HAMR) process is also discussed. The mechanical properties of Ti-6Al-4V produced using various PM processes are analyzed based on their dependence on unique microstructural features, oxygen content, porosity, and grain size. In particular, the fatigue properties of PM Ti-6Al-4V are examined as functions of microstructure. A hydrogen-enabled approach for microstructural engineering that can be used to produce PM Ti with wrought-like microstructure and properties is also presented. Abbreviations: AM: additive manufacturing; ARC: Albany Research Center; BE: blended elemental; BUS: broken-up structure; CCGA: close-coupled gas atomisation; CHIP: CIP-sinter-HIP; CIP: cold isostatic pressing; CP-Ti: commercially pure Ti; DRTS: direct reduction of Ti-slag; CSIR: Council for Scientific and Industrial Research (South Africa); CSIRO: Commonwealth Scientific and Industrial Research Organization (Australia); EIGA: electrode induction gas atomisation; EMR: electronically mediated reduction; FFC: Fray, Farthing, and Chen; GA: gas atomisation; GIF: gaseous isostatic forging; GSD: granulation-sintering-deoxygenation; HAMR: hydrogen-assisted magnesium reduction; HDH: hydride-dehydride; HIP: hot isostatic pressing; HSPT: hydrogen sintering and phase transformation; MA: master alloy; MER: Materials & Electrochemical Research Corporation (US); MHR: metal hydride reduction; MIM: metal injection molding; OM: optical microscope; OS: Ono and Suzuki; PA: pre-alloyed; P/C: performance to cost ratio; PIF: pneumatic isostatic forging; PM: powder metallurgy; PREP: plasma rotating electrode process; PP: post-processing; PS: press and sinter; QIT: Quebec Iron & Titane, Inc. (Canada); SEM: scanning electron microscope; SPS: spark plasma sintering; SOM: solid oxide membrane; THP: thermohydrogen processing; TMP: thermomechanical processing; UFG: ultrafine grain; UGS: upgraded titanium slag; UTS: ultimate tensile strength; USTB: University of Science and Technology Beijing (China); VA: vacuum atomisation; VHP: vacuum hot pressing; WP: wrought process; YS: yield strength [ABSTRACT FROM AUTHOR]

Thermodynamics analysis and affecting factors of vacuum distillation on removal of chloride impurities from titanium sponge were studied. The theoretical results show that volatilization ability of Mg,MgCl 2 , TiCl 2 and TiCl 3 are very strong under vacuum when distillation temperature is more than 800 °C. And chloride impurities could be removed more effectively by improving volatilization rate of MgCl 2 at 900 °C–1050 °C with lower residual system pressure. Experimental results showed that chlorine content in the titanium sponge significantly increased with the increasing of system pressure and chlorine content in magnesium reductant. Meanwhile, the removal of chlorine from titanium sponge was very temperature and distillation time dependent. In addition, the chloride impurities were more difficult to be removed with the decreased porosity of titanium sponge. Finally, optimized parameters for distillation furnace with single batch production capacity of 7.5t titanium sponge were achieved. The chlorine content in final titanium sponge product can be controled at or lower than 0.06 wt% when the distillation temperature, system pressure, and distillation time were 980 °C–1000 °C, 0.1 Pa–3 Pa and 150 h–157 h respectively. [ABSTRACT FROM AUTHOR]

Commercially pure titanium (CP Ti) and Ti-6Al-4V arms for a new brand of augmented reality smart glasses, which are over 170 mm in length, with thin wall structures and extremely complex surfaces, have been successfully fabricated via metal injection molding. After sintering, both the metal injection-molded (MIMed) CP Ti and Ti-6Al-4V can reach relative densities of over 95% with an oxygen content ~ 2200 ppm, thus imparting mechanical properties comparable to cast alloys. The ductility of the MIMed CP Ti and Ti-6Al-4V are about 15% and 8%, respectively. This is a good example of applying metal injection molding to mass production of precise Ti alloy parts with complicated shapes. [ABSTRACT FROM AUTHOR]

The anodic oxidation of a titanium metal electrode in two ionic liquids was studied of amorphous titania nanostructures were obtained. The nanostructures are formed only in the case where a hydrophilic ionic liquid (1-butyl-3-methylimidazolium chloride) with addition of some water is used as the electrolyte. The role of water is to provide a sort of construction material (source of oxygen) for titania nanostructures. In the hydrophobic ionic liquid (1-butyl-3-methylimidazolium), the thickness of the anodic oxide increases and no nanostructures are formed. [ABSTRACT FROM AUTHOR]

With the aim of avoiding the composition modification of titanium particles and substrate degradation during conventional thermal spray process, a combination process of cold spraying and dry-ice blasting was used in the present study to deposit titanium coatings on different metallic substrates. Moreover, a tentative study on cold spraying of titanium coatings on non-metallic surfaces such as polymers was carried out by profiting the texturing potential of dry-ice blasting. The deposition characteristics of titanium particles were examined in terms of deposition efficiency, coating microstructure, microhardness and bonding strength. Only several titanium particles were embedded into polymer with no build-up of a layer or coating in spite of dry-ice blasting application. Titanium coatings coated on metallic substrates exhibited a porous structure and no obvious difference in outer and inner microstructure was distinguished. In addition, dry-ice blasting has a positive improvement in bonding strength between titanium coatings and relatively soft metallic substrate. [ABSTRACT FROM PUBLISHER]

A Ti(C, N)-based cermet cutting tool material with satisfactory properties was fabricated in an energy-efficient way by microwave sintering. The effect of microwave singtering process and the component ratio of carbide (WC, Mo 2 C) on phase composition, microstructure and mechanical properties were studied. The cermet containing 5 wt% WC and 15 wt% Mo 2 C microwave sintered at 1400 ℃ for 10 min, got the optimal mechanical properties. The relative density, fracture toughness and Vicker's hardness were 97.2 ± 0.5%, 8.24 ± 0.49 MPa m 1/2 and 17.54 ± 0.66 GPa, respectively. The microwave sintering temperature and holding time decreased by 1.4~15.25% and 66.7~96.1% in comparison with conventional sintering. Solid solution (Ti, Mo)C 2 and (W, Ti)C without nitrogen formed, which was different from the carbonitride solid solution that formed in conventional sintering. Additionally, long holding time brought about the formation of whisker-like materials, which benefited the fracture toughness. [ABSTRACT FROM AUTHOR]

Sodium aluminate (NaAlO) concentration was varied in order to understand the influence of the chemical composition of electrolyte on the spark characteristics, microstructure, and corrosion behavior of plasma electrolytic oxidation (PEO) coatings. For this purpose, PEO coatings were formed on the pure titanium substrate surface using solutions of four diverse sodium aluminate concentrations (6, 8, 10, and 12 g/L). The PEO process was carried out at constant time and voltage (180 seconds and 420 V). Studying the microstructures of samples by scanning electron microscope (SEM) and their corrosion behavior in 3.5 wt pct NaCl solutions indicated that the increase in NaAlO concentration (up to 10 g/L) led to an increase in uniformity and compactness, thus decreasing the size of micro-pores and increment of corrosion resistance. However, at a certain level of NaAlO concentration (12 g/L), large and severe sparks were created on the surface of the sample during the process, worsening the corrosion resistance and microstructure of coating. [ABSTRACT FROM AUTHOR]

A new simple powder metallurgy process by sintering TiH powders was used to manufacture porous Ti components. The effects of the processing parameters (pressure of cold isostatic pressing and sintering temperature) and the TiH/Ti ratio in the powder mixtures on the impurities, the linear shrinkage and the pore properties (including overall and open porosities) were comprehensively determined. The addition of TiH as a reactant has been found beneficial for the synthesis of porous Ti components. The formation mechanisms of pores were demonstrated based on the dehydrogenation process of TiH during sintering, resulting in highest reactivity due to the 'in statu nascendi' generation of the metal. In addition, the hardness and corrosion resistance of all the sintered samples were evaluated, related to the overall and open porosities. As a result, an optimal composition of Ti-40 wt.% TiH was defined, as its maximum open porosity was about 23%. [ABSTRACT FROM AUTHOR]

Wire-feed additive manufacturing is cost competitive and efficient in producing large and complex components in aerospace applications. However, for the additive manufacturing technologies with lateral wire feeding, including laser wire additive manufacturing, electron beam freeform fabrication, plasma arc welding, and gas tungsten arc welding, it is difficult to obtain uniform deposit due to the variable wire feeding direction. In this work, high-angle wire feeding method is proposed to obtain uniform deposit in gas tungsten arc welding-based additive manufacturing. The results illustrate that low wire feeding angle (30°–50°) causes the deposition to break at the back feeding, meanwhile too high wire feeding angle (70°) leads to many littered droplets on one side of the deposition at the condition of side feeding. A uniform deposition can be obtained at the optimal wire feeding angle of 60° in any wire feeding direction, and the reasons have been discussed based on the temperature distribution characteristics of the arc and molten pool. Furthermore, the deposition layers exhibit similar columnar priorβgrains, basketweave microstructure, and tensile properties from different wire feeding directions. [ABSTRACT FROM AUTHOR]

In this work, C 120 -nanotorus, were decorated with Ti atoms, and structural, thermodynamic and chemical properties were theoretical investigated using the Density Functional Theory (DFT) calculations under Accelrys, Materials Studio Dmol3 library. Nowadays, the hydrogen is considered as an energy vector, besides it is not a pollutant and it is very abundant. There exists a wide consensus among scientists and specialists about theoretical and applied hydrogen science and technology that some of the biggest problems is the hydrogen safe storage and shipper catalytic materials in the hydrogen application as an electric source. According to this we had been studying some nanostructures that could be good and safe hydrogen storage materials. For this reason, we propose C 120 +nTi nanotorus as a good hydrogen absorber material since we found it presents highly hydrogen storage capacity, around of 5.6 wt%, it has a good thermal resistance, <100 °C, and expected proper catalytic properties for hydrogen storage purpose. In addition, the presented simulated material, as a new nanostructure, presents high structural and chemical stability implying with a good hydrogen gravimetric capacity weight %, which makes it an excellent option for our purpose. [ABSTRACT FROM AUTHOR]

The pre-heat treatment in vacuum rapid nitriding process was introduced to improve the surface hardening characteristics such as thick depth, high hardness and particularly to reduce the processing time. The pre-heat treatment was maintained for 30 min with an interval of 10 °C at the temperatures of 700– 800 °C under a high vacuum to allow the absorption of oxygen atoms on the titanium surface into the inner side. The following nitriding processes were equally performed at the same condition as 800 °C for 1 h. As a result, the depth of a hardened layer in the sample, which was treated at 800 °C for 1 h with the pre-heat treatment at 760 °C for 30 min, was similar to that of the treated sample at 800 °C for 3 h without pre-heat treatment and the depth was about 40 μm. The processing time can be largely reduced by introducing the pre-heat treatment process. The pre-heated specimens showed a longer wear lifetime by more than three times and higher friction resistance than that of PVD or non-nitrided specimens. The surface gradient-hardened layers exhibited excellent wear resistance and could prevent separation or debonding between matrix and the coated layer effectively. [ABSTRACT FROM AUTHOR]

The paper proposes a new technique of recycling metallic chips and presents the results of examination of the products thus obtained. The aim of the experiments was to recycle commercial purity (cp) titanium Grade 2 chips obtained by turning, and to produce a solid bulk material. The recycling was realized using a plastic working process. The titanium chips were first subjected to preliminary consolidation and then directly extruded using the KOBO process. The properties of the recycling final product were examined and compared with those of the as-received, solid cp-titanium Grade 2 (reference material). The recycling process yielded a well consolidated solid titanium rod with a diameter of 8 mm. The consolidation effect was high which was confirmed by the fact that only a small number of voids and discontinuities distributed randomly were observed. The final material had a homogeneous grained structure. The equiaxial grains observed on the transverse and longitudinal sections had similar sizes. The mechanical properties of the recycled material (estimated based on the results of microhardness measurements and uniaxial compression tests) were comparable with those of solid cp-titanium Grade 2. [ABSTRACT FROM AUTHOR]

In this paper, a method of forming hard, wide-area, crack-free, and wear-resistant nitrided cases on commercially-pure titanium using a 3.5 kW CO 2 laser-sustained plasma is described. This surface hardening method was comprised of two steps: (1) a laser-sustained nitrogen plasma was first used to nitride the titanium substrate; and (2) a laser-sustained argon plasma was then employed to remelt the nitrided layer deposited in the first step. Previous research using single laser trail experiments had shown that the (second) remelting step can eliminate cracks formed during the (first) nitriding step and homogenize the nitrided layer. In this work, the two-step nitriding-remelting process was extended to wider surface areas by depositing multiple overlapping trails at four different nitriding speeds and a constant remelting speed. The hardened layer was characterized using x-ray diffraction (XRD), optical metallography, and hardness testing. Reciprocating ball-on-flat wear tests were conducted to assess the wear resistance of the nitrided case, with the wear scar being characterized using scanning electron microscopy (SEM) and optical profilometry. Crack-free, hard cases of depths up to 600 μm and average hardness values up to 641 ± 86 HV 0.3 were observed. The LSP nitriding-remelting treatment was found to improve the wear resistance of the base metal (CP-Ti) by up to 80%. [ABSTRACT FROM AUTHOR]

Oxides of titanium have found applications in areas such as energy capture, cell attachment to biomedical devices and as catalytic surfaces. This study demonstrates that the use of a microwave plasma can significantly enhance both titanium oxide formation and growth rate, compared with those obtained using conventional furnace treatments. The ability of microwave plasma treatments to control the thickness and morphology of oxides grown on titanium substrates is demonstrated. For a fixed plasma treatment time of 10 min, depending on the input power and treatment pressure, the oxide-layer thickness of between 0.69 and 10.45 μm were obtained. The associated roughness (R a ) values were in the range of 0.11–0.67 μm. This study demonstrated that the morphology of the oxide-layer was particularly influenced by the input power to the plasma, while oxide thickness was depended on the treatment pressure and time. The mechanism of titanium oxidation was also investigated and based on the homogeneous oxidation observed across the titanium metal surface (under the oxide layer), it is also concluded that the mechanism of oxidation is ‘general corrosion’. [ABSTRACT FROM AUTHOR]

We successfully synthesized willow leaf-like plasmonic Ti3+ doped Au/Cl-TiO2 mesocrystals by facile modified two-phase vapor hydrolysis and photoreduction methods. In this work, the as-prepared Ti3+ doped TiO2 mesocrystals showed an interesting visible light harvesting capacity and visible light photocatalytic activity for hydrogen production. The plasmonic Ti3+ doped Au/Cl-TiO2 mesocrystals also showed highly enhanced visible light absorption and visible light photocatalytic activity for hydrogen production, and the highest visible light photocatalytic activity reached 480.1 μmol g−1 h−1, which was 208.70 times as high as that of P25 TiO2 and 1.59 times as high as that of Ti3+ doped TiO2 mesocrystals. Finally, the possible visible light photocatalytic mechanisms of plasmonic Ti3+ doped Au/Cl-TiO2 mesocrystals for hydrogen production were proposed. [ABSTRACT FROM AUTHOR]

Al-5Ti-1B master alloys were prepared by reacting K 2 TiF 6 and KBF 4 salts with Al melt. During the reaction period between the fluoride salts and Al melt, the non-homogenous distribution of solutes B and Ti in the Al melt close to the salts/Al melt interface causes the formation of the unstable AlB 2 phase. The AlB 2 phase transforms to TiB 2 particles by the diffusion of solutes Ti and B in the Al melt during the afterward holding temperature period, which causes an increase both in the number density of TiB 2 particles and in the grain refining efficiency of the master alloys. After the transformation of AlB 2 phase to TiB 2 phase, TiB 2 particles coarsen by Ostwald ripening, which leads to a decrease both in the number density of TiB 2 particles and in the grain refining efficiency of the master alloys. [ABSTRACT FROM AUTHOR]

Knowledge of the cyclic properties of metallic materials is often critical to correctly design structural components. However, cyclic data are not easily available in the literature, while tensile test data are easier to find in specialized sites or vendor catalogs. In this study, the cyclic strength coefficient and the cyclic strain hardening exponent of the Ramberg-Osgood law were evaluated using exclusively data obtained through monotonic tensile tests. The analyses were carried out on a large set of materials. The database used is composed of 338 alloys, mainly iron alloys, but also titanium and aluminum alloys. New subdivisions of the materials were introduced. Several original relations were suggested to correlate static and cyclic strength parameters. The evaluated values of both cyclic strength coefficient and cyclic strain hardening exponent were compared with experimental values coming from cyclic test, obtaining a satisfactory agreement and a higher accuracy if compared with similar relations found in the literature. [ABSTRACT FROM AUTHOR]

Separating oil from oily water and degrading the aqueous pollutants are two significant issues of wastewater treatment. In this work, a titanium mesh coated with W, N co-doped TiO 2 nanobelts (WNTNBs) was prepared through a simple solution route, followed by a subsequent calcination. The hierarchical nanobelt structures on the mesh contributed to considerable surface roughness, resulting in the excellent superhydrophilicity and underwater superoleophobicity. The mesh could keep its wetting performance in corrosive environments such as highly saline, acidic and alkaline conditions, revealing good environmental stability. This durable mesh is efficient for separating oil from water with high separation efficiency, as well as degrading soluble dyes such as methylene blue (MB) in the water phase even under visible light irradiation. Moreover, the mesh possesses good self-cleaning property on the removal of aqueous insoluble oil on its surface in the presence of ultraviolet and visible light, making it more effective and promising in wastewater treatment. [ABSTRACT FROM AUTHOR]

In this study, fully dense commercially pure titanium (CP Ti) parts were successfully fabricated by selective laser melting (SLM) using the same optimal laser energy density E p ¯ but with two different laser powers: high laser power E H ~ 250 W and low laser power E L ~ 50 W. It was found that at the same E p ¯ different laser powers led to different phase formation, microstructure, texture and mechanical properties of the selective laser melting fabricated (SLMed) CP Ti. A weak-textured CP Ti with isotropic mechanical properties was achieved using E H while a strong-textured CP Ti with anisotropic mechanical properties was obtained using E L . The underlying mechanism was attributed to the formation of α' phase in the CP Ti as a result of the higher cooling rates at E H . The formation of α' phase also contributed to the observed high ultimate compressive strength ~ 1.1 GPa and high compressive strain ≥ 50% in the SLMed weak-textured CP Ti at E H . This study provides important insights into the role of laser energy in the SLM fabrication of CP Ti with tailorable crystallographic texture and thus mechanical properties. [ABSTRACT FROM AUTHOR]

In the present work, we report a novel bimodal and multi-layered grain structure in pure titanium produced via powder metallurgy. It was found that the hot-extruded pure Ti consists of multiple grain layers, which exhibited substantially different mean grain sizes. The microstructural development during hot extrusion was then investigated for the pure Ti via an interrupted extrusion experiment. The influence of this unique structure on the mechanical properties of the material was also studied under uniaxial quasi-static tension. The experimental results showed that the samples with different arrangement of the grain layers exhibited very different mechanical behavior. Namely, with combining a small part of fine grain layers, the material showed significantly increased yield strength and slightly decreased uniform plastic strain. Yet, the elongation-to-failure was decreased markedly for the multilayered material. Postmortem examinations indicated that this may attribute to the absence of deformation twins in the fine grains that leads to formation of microvoids, which finally develop into large cracks. [ABSTRACT FROM AUTHOR]

The hat-shaped samples cut from rolled and annealed titanium plates were prepared to explore the adiabatic shear behaviors subjected to high-strain-rate deformation operated via Split Hopkinson Pressure Bar. The dynamic shear response calculation reveals that dynamic deformation processes of both state samples can be divided in similar three stages but rolled sample shows a higher susceptibility of adiabatic shear localization compared with the annealed one. Optical microscopy and electronic backscatter diffraction technique (EBSD) were used to systematically analyze the microstructure and texture characteristics. The results show that adiabatic shear bands form in both state samples and rotational dynamic recrystallization (RDRX) occurs within shear area and results in the formation of ultrafine equiaxed grains. Furthermore, ultrafine equiaxed grains within adiabatic shear bands have the same texture feature that <11–20> direction and {10-10} plane parallel to macro local shear direction and shear plane respectively. In the deformation region around the shear band, {10–12} <–1011> tensile and {11–22} <11-2-3> compressive two types twins are observed in both state samples and {10–12} <–1011> tensile twins are more frequently observed in rolled sample. In the rolled sample, {10–12} <–1011> tensile twins are more likely to happen in the hat-brim side than the hat-body side due to the difference of stress state in two sides. [ABSTRACT FROM AUTHOR]

The present investigation is conducted to successfully deform a commercially pure titanium as a hard-to-deform metal by equal-channel angular pressing (ECAP, φ = 90°) using core-sheath configuration at room temperature. Analyzing the flow behavior of metal via three-dimensional finite element modeling (FEM) and analytical calculation reveals that the friction force between the sheath and inner surface of the die in the exit channel is the source of back pressure and its magnitude is dependent on the length of the billet and strength of the sheath. The ultimate tensile strength of Ti increases by a factor of ≈1.8 after processing through one pass of ECAP and the material exhibits total elongation of ≈17% after testing at room temperature, regardless of core size. [ABSTRACT FROM AUTHOR]

In the present study, the moisture of high titanium slag was chosen as the research object. Taking advantage of selective heating of microwave and the specific inductive capacity of water, the drying experiment of high titanium slag using microwave heating have been carried out. The results revealed that the presence of moisture in the form of high titanium slag was adsorbed water, and the wet sample possesses excellent wave-adsorbing performance; the bed depth preferred was no larger than 10 mm, with moisture content at around 3%. The microwave drying process was divided into two stages: the constant-stage and the deceleration-stage. The optimum conditions were identified to be microwave power of 700 W, sample mass of 200 g, bed depth of 10 mm and drying time of 50 s. The dehydration extent can reach 90% and moisture content remains at 0.3% under the optimum conditions. The demonstration of microwave drying techniques can be applied effectively and efficiently into the treatment processing of drying of the raw materials of metallurgy and chemical industry with the theoretical and scientific basis. [ABSTRACT FROM AUTHOR]

The clinical success of coated implants in executing biological functions inclusive of sustainable drug release and long term antibacterial activity without antibiotics is critical. To this aim, a nanohybrid of silver nanoparticles (AgNPs) cored in polyvinyl alcohol nanocapsules (Ag-PVA NCs) embedded in chitosan (CS) matrix loaded with anti-inflammatory drug naproxen was prepared. The synthesized nanohybrids that were subjected to coatings on (3-aminopropyl)triethoxysilane (APTES) treated titanium (Ti) metal exhibited dual role of excellent inhibition on biofilm formation and sustained drug release. These dual characteristics are achieved mainly based on intrinsic antibacterial property of AgNPs and differential entrapment of drug in PVA polymeric shell of AgNPs and CS matrix. The coatings also demonstrated enhanced mechanical properties with increasing inorganic filler and stress shielding on Ti metal. The biocompatibility tests involving adhesion, proliferation and differentiation of osteoblast cells demonstrated the efficacy of Ag-PVA NCs embedded in CS matrix as a suitable coating material for orthopedic applications. [ABSTRACT FROM AUTHOR]

Twin interactions associated with {11 $$ \overline{2} $$ 1} (E2) twins in titanium deformed by high strain rate (~2600 s) compression were studied using electron backscatter diffraction technique. Three types of twins, {10 $$ \overline{1} $$ 2} (E1), {11 $$ \overline{2} $$ 2} (C1), and {11 $$ \overline{2} $$ 4} (C3), were observed to interact with the preformed E2 twins in four parent grains. The E1 variants nucleated at twin boundaries of some E2 variants. And the C3 twins were originated from the intersection of C1 and E2. The selection of twin variant was investigated by the Schmid factors (SFs) and the twinning shear displacement gradient tensors (DGTs) calculations. The results show that twin variants that did not follow the Schmid law were more frequently observed under high strain rate deformation than quasi-static deformation. Among these low-SF active variants, 73 pct (8 out of 11) can be interpreted by DGT. Besides, 26 variants that have SF values close to or higher than their active counterparts were absent. Factors that may affect the twin variant selections were discussed. [ABSTRACT FROM AUTHOR]

In this work, the electrolysis of Reactive Blue 19 (RB-19, a toxic textile dye with a high half-life) using a highly non-commercial boron-doped diamond film on titanium substrate (BDD/Ti) was studied. The BDD film with a B/C ratio of 15,000 ppm, a doping level around 10 19 cm −3 and higher content of sp 3 (diamond) than sp 2 (graphite) was produced with high quality and stability. Under appropriate conditions, the electrode promoted complete decolorization of RB-19, together with 99% of TOC removal and a significant decrease in toxicity against V. fischeri . Furthermore, benzene rings, aromatic amines and naphthalene could be removed also during the electrodegradation. The decay in dye concentration followed pseudo-first order kinetics and the values of the apparent rate constant increased with increasing current density applied. In addition, the main intermediates compounds of RB-19 degradation on BDD/Ti based on HPLC–MS analysis were amino-anthraquinone, tautomers keto-enolic, hydroquinone and benzoquinone, benzoic acid, phenol and acid aliphatic, such as oxalic acid. It is concluded that electrochemical oxidation using a BDD/Ti anode represents a satisfactorily method for the removal of RB-19 in aqueous solutions. [ABSTRACT FROM AUTHOR]

We report an efficient thermoelectric device with power density of 8.9 W/cm and efficiency of 8.9% at 678°C temperature difference using hot-pressed titanium metal contact layers on nanostructured half-Heusler materials. The high power density and efficiency are due to the efficient nanostructured materials and very low contact resistance of ~1 μΩ cm between the titanium layer and half-Heusler material. Moreover, the bonding strength between the titanium and half-Heusler is more than 50 MPa, significantly higher compared with conventional contact metallization methods. The low contact resistance and high bonding strength are due to thin-layer diffusion of titanium (<100 μm) into the half-Heusler at high temperature (>600°C). The low contact resistance and high bonding strength result in a stable and efficient power generation device with great potential for use in recovery of waste heat, e.g., in automotive and industrial applications. [ABSTRACT FROM AUTHOR]