Zirconia has excellent mechanical properties, such as high fracture toughness, wear resistance, and flexural strength, which make it a candidate for application in bead mills as milling media as well as a variety of components. In addition, enhanced mechanical properties can be attained by adding oxide or non-oxide dispersing particles to zirconia ceramics. In this study, the densification and mechanical properties of YSZ-TiC ceramic composites with different TiC contents and sintering temperatures are investigated. YSZ - x vol.% TiC (x=10, 20, 30) system is selected as compositions of interest. The mixed powders are sintered using hot pressing (HP) at different temperatures of 1300, 1400, and 1500oC. The densification behavior and mechanical properties of sintered ceramics, such as hardness and fracture toughness, are examined.

Fe-30 wt% TiC composite powders are fabricated by in situ reaction synthesis after planetary ball millingof (Fe, TiH2, Carbon) powder mixture. Two sintering methods of a pressureless sintering and a spark-plasma sinteringare tested to densify the Fe-30 wt% TiC composite powder compacts. Pressureless sintering is performed at 1100, 1200and 1300oC for 1-3 hours in a tube furnace under flowing argon gas atmosphere. Spark-plasma sintering is carried outunder the following condition: sintering temperature of 1050oC, soaking time of 10 min, sintering pressure of 50 MPa,heating rate of 50oC/min, and in a vacuum of 0.1 Pa. The curves of shrinkage and its derivative (shrinkage rate) areobtained from the data stored automatically during sintering process. The densification behaviors are investigated fromthe observation of fracture surface and cross-section of the sintered compacts. The pressureless-sintered powder com-pacts are not densified even after sintering at 1300oC for 3 h, which shows a relative denstiy of 66.9%. Spark-plasmasintering at 1050oC for 10 min exhibits nearly full densification of 99.6% relative density under the sintering pressure of50 MPa.

Two sintering methods of a pressureless sintering and a spark-plasma sintering are tested to densify the Fe-TiC composite powders which are fabricated by high-energy ball-milling. A powder mixture of Fe and TiC is prepared in a planetary ball mill at a rotation speed of 500 rpm for 1h. Pressureless sintering is performed at 1100, 1200 and 1300oC for 1-3 hours in a tube furnace under flowing argon gas atmosphere. Spark-plasma sintering is carried out under the following condition: sintering temperature of 1050oC, soaking time of 10 min, sintering pressure of 50 MPa, heating rate of 50oC, and in a vacuum of 0.1 Pa. The curves of shrinkage and its derivative (shrinkage rate) are obtained from the data stored automatically during sintering process. The densification behaviors are investigated from the observation of fracture surface and cross-section of the sintered compacts. The pressureless-sintered powder compacts show incomplete densification with a relative denstiy of 86.1% after sintering at 1300oC for 3h. Spark-plasma sintering at 1050oC for 10 min exhibits nearly complete densification of 98.6% relative density under the sintering pressure of 50 MPa.

Fe-TiC composite powders are fabricated by planetary ball mill processing. Two kinds of powder mixtures are prepared from the starting materials of (a) (Fe, TiC) powders and (b) (Fe, TiH2, Carbon) powders. Milling speed (300, 500 and 700 rpm) and time (1, 2, and 3 h) are varied. For (Fe, TiH2, Carbon) powders, an in situ reaction synthesis of TiC after the planetary ball mill processing is added to obtain a homogeneous distribution of ultrafine TiC particulates in Fe matrix. Powder characteristics such as particle size, size distribution, shape, and mixing homogeneity are investigated. In case of (Fe, TiC) powder many coarse TiC particulates with size of several μm are unevenly distributed in Fe-matrix. The composite powder prepared from (Fe, TiH2, C) powder mixture showed a homogeneous dispersion of ulatrafine TiC particulates.

Fe-TiC composite powder was fabricated by high-energy milling of powder mixture of (Fe, TiC) and (FeO, TiH2, C) as starting materials, respectively. The latter one was heat-treated for reaction synthesis of TiC phase after milling. Both powders were spark-plasma sintered at various temperatures of 680-1070℃ for 10 min. with sintering pressure of 70 MPa and the heating rate of 50℃/min. under vacuum of 0.133 Pa. Density and hardness of the sintered compact was investigated. Fe-TiC composite fabricated from (FeO, TiH2, C) as starting materials showed better sintered properties. It seems to be resulted from ultra-fine TiC particle size and its uniform distribution in Fe-matrix compared to the simply mixed (Fe, TiC) powder.

The deformation properties of a TiC-Mo eutectic composite were investigated in a compression test at temperaturesranging from room temperature to 2053K and at strain rates ranging from 3.9×10−5s−1 to 4.9×10−3s−1. It was found that thismaterial shows excellent high-temperature strength as well as appreciable room-temperature toughness, suggesting that thematerial is a good candidate for high-temperature application as a structure material. At a low-temperature, high strength isobserved. The deformation behavior is different among the three temperature ranges tested here, i.e., low, intermediate and high.At an intermediate temperature, no yield drop occurs, and from the beginning the work hardening level is high. At a hightemperature, a yield drop occurs again, after which deformation proceeds with nearly constant stress. The temperature- andyield-stress-dependence of the strain is the strongest in this case among the three temperature ranges. The observed high-temperature deformation behavior suggests that the excellent high-temperature strength is due to the constraining of thedeformation in the Mo phase by the thin TiC components, which is considerably stronger than bulk TiC. It is also concludedthat the appreciable room-temperature toughness is ascribed to the frequent branching of crack paths as well as to the plasticdeformation of the Mo phase.

Fe-TiC composite was fabricated from Fe and TiC powders by high-energy milling and subsequent spark- plasma sintering. The microstructure, particle size and phase of Fe-TiC composite powders were investigated by field emission scanning electron microscopy and X-ray diffraction to evaluate the effect of milling conditions on the size and distribution of TiC particles in Fe matrix. TiC particle size decreased with milling time. The average TiC particle size of 38 nm was obtained after 60 minutes of milling at 1000 rpm. Prepared Fe-TiC powder mixture was densified by spark- plasma sintering. Sintered Fe-TiC compacts showed a relative density of 91.7~96.2%. The average TiC particle size of 150 nm was observed from the FE-SEM image. The microstructure, densification behavior, Vickers hardness, and frac- ture toughness of Fe-TiC sintered compact were investigated.

Fe-TiC composite powder was fabricated via two steps. The first step was a high-energy milling of FeO and carbon powders followed by heat treatment for reduction to obtain a (Fe+C) powder mixture. The optimal condition for high-energy milling was 500 rpm for 1h, which had been determined by a series of preliminary experiment. Reduction heat-treatment was carried out at for 1h in flowing argon gas atmosphere. Reduced powder mixture was investigated by X-ray Diffraction (XRD), Field Emission-Scanning Electron Microscopy (FE-SEM) and Laser Particle Size Analyser (LPSA). The second step was a high-energy milling of (Fe+C) powder mixture and additional powder, and subsequent in-situ synthesis of TiC particulate in Fe matrix through a reaction of carbon and Ti. High-energy milling was carried out at 500 rpm for 1 h. Heat treatment for reaction synthesis was carried out at for 1 h in flowing argon gas atmosphere. X-ray diffraction (XRD) results of the fabricated Fe-TiC composite powder showed that only TiC and Fe phases exist. Results from FE-SEM observation and Energy-Dispersive X-ray Spectros-copy (EDS) revealed that TiC phase exists uniformly dispersed in the Fe matrix in a form of particulate with a size of submicron.

The Fe-based self-fluxing alloy powders and TiC particles were ball-milled and subsequently compacted and sintered at various temperatures, resulting in the TiC particle-reinforced Fe self-fluxing alloy hybrid composite, and the microstructure and micro-hardness were investigated. The initial Fe-based self-fluxing alloy powders and TiC particles showed the spherical shape with a mean size of approximately 80 and the irregular shape of less than 5 , respectively. After ball-milling at 800 rpm for 5 h, the powder mixture of Fe-based self-fluxing alloy powders and TiC particles formed into the agglomerated powders with the size of approximately 10 that was composed of the nanosized TiC particles and nano-sized alloy particles. The TiC particle-reinforced Fe-based self-fluxing alloy hybrid composite sintered at 1173 K revealed a much denser microstructure and higher micro-hardness than that sintered at 1073 K and 1273 K.

Ultra-fine TiC/Co composite powder was synthesized by the carbothermal reduction process without wet chemical processing. The starting powder was prepared by milling of titanium dioxide and cobalt oxalate powders followed by subsequent calcination to have a target composition of TiC-15 wt.%Co. The prepared oxide powder was mixed again with carbon black, and this mixture was then heat-treated under flowing argon atmosphere. The changes in the phase, mass and particle size of the mixture during heat treatment were investigated using XRD, TG-DTA and SEM. The synthesized oxide powder after heat treatment at 700 has a mixed phase of TiO and CoTiO phases. This composite oxide powder was carbothermally reduced to TiC/Co composite powder by the solid carbon. The synthesized TiC/Co composite powder at 1300 for 9 hours has particle size of under about 0.4 m.

Wear of steel plate was measured during unlubricated sliding against TiC composites. These composites consist of round TiC grains and steel matrix. TiC grain itself exhibits low surface roughness and round shape, which does not bring its counterpart into severe damage from friction. In our work a classical experimental design was applied to find out a dominant factor in counterpart wear. The analysis of the data showed that only the applied load has a significant effect on the counterpart wear. Wear rate of counterpart increased non-linearly with applied load. Amount of wear was discrepant from expectation of being in proportion to the load by analogy with friction force. Our experimental result from treating matrix variously revealed bimodal wear behavior between the composites and counterpart where a mode seems to result from the special lubricant characteristic of TiC grains, and the other is caused by metal-to-metal contact. The two wear mechanisms were discussed.

TiC-TiB2-SiC system was a ternary eutectic, whose eutectic composition was 34TiC-22TiB2-44SiC (mol%). TiC-TiB2-SiC ternary eutectic composite were synthesized by a floating zone method using TiC, TiB2 and SiC powders as starting materials. The TiC-TiB2-SiC eutectic composite showed a lamellar texture. TiC(022), TiB2(010) and SiC(111) of the eutectic composite were perpendicular to the growth direction. TiC-TiB2-SiC ternary eutectic composite had specific relationship among the crystal planes: TiC[011]//TiB2[010]//SiC[112], TiC(200)//TiB2(001)//SiC( 402 ) and TiC( 111 )//TiB2(101 )//SiC( 220 ).

In the present, the focus is on the synthesis of nanostructured TiC/Co composite powder by the spray thermal conversion process using titanium dioxide powder has an average particle size of 50 nm and cobalt nitrate as raw materials. The titanium-cobalt-oxygen based oxide powder prepared by the combination of the spray drying and desalting methods. The titanium-cobalt-oxygen based oxide powder carbothermally reduced by the solid carbon. The synthesized TiC-15wt.%Co composite powder at 1473K for 2 hours had an average particle size of 150 nm.

In the present study, the focus is on the synthesis of titanium carbide/cobalt composite powder by the spray thermal conversion process using metallic salt solution as the raw materials. Two types of oxide powders of Ti-Co-O system were prepared by the spray drying of two types of metallic salt solutions : titanium chloride-cobalt nitrate and powder-cobalt nitrate solutions. These oxide powders were mixed with carbon black, and then these mixtures were carbothermal reduced under a flowing argon atmosphere. The changes in the phase structure and thermal gravity of the mixtures during carbothermal reduction were analysed using XRD and TG-DTA. In the case of using the titanium chloride-cobalt nitrate solution, it could not be obtained TiC/Co composite powder due to contamination of the impurities during the spray drying of the solution. However, in tile case of using the powder-cobalt nitrate scullion, TiC-15 wt. %Co composite powder could be synthesized by the spray thermal conversion process. The synthesized TiC-15 wt. %Co composite powder at 120 for 2 hours has average particle size of 150 nm.