The tribological properties of TiC, TiN and TiC/TiN coatings on steels prepared by the cathodic-arc (CA) ion plating technique were investigated. Experiments were carried out on a tribo-test machine using a Falex journal V block system. The friction and wear characteristics of the coatings were determined by varying the applied load and sliding speed. The TiC, TiN and TiC/TiN coatings markedly increased the tribological characteristics of the surface. As far as a single layer coating was concerned, TiN goes better results than TiC. However, the TiC/TiN multilayer coating performed better than either single layer coating. The major factor in the improved performance of the multilayer coating was the role of TiC in improving the adhesion between the external TiN layer and the substrate steel.

Aluminum-based powders have attracted attention as key materials for 3D printing owing to their low density, high specific strength, high corrosion resistance, and formability. This study describes the effects of TiC addition on the microstructure of the A6013 alloy. The alloy powder was successfully prepared by gas atomization and further densified using an extrusion process. We have carried out energy dispersive X-ray spectrometry (EDS) and electron backscatter diffraction (EBSD) using scanning electron microscopy (SEM) in order to investigate the effect of TiC addition on the microstructure and texture evolution of the A6013 alloy. The atomized A6013-xTiC alloy powder is fine and spherical, with an initial powder size distribution of approximately 73 μm which decreases to 12.5, 13.9, 10.8, and 10.0 μm with increments in the amount of TiC.

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.

Monte-Carlo Tree Search (MCTS) is a best-first search algorithm to evaluate states of the game tree in game playing, and has been successfully applied to various games, especially to the game of Go. Upper Confidence Bounds for Trees (UCT), which is a variant of MCTS, uses the UCB1 formula as selection policy, and balances exploitation and exploration of the states. Rapid Action-Value Estimation (RAVE), which is a All-Moves-As-First (AMAF) heuristic, treats all moves in a simulation as the first move, and therefore updates the statistics of all children of the root node. In this paper, we evaluate the performance of RAVE and UCT playing against each other in the game of Tic-Tac-Toe. The experimental results show that the first player RAVE is much inferior to the second player UCT (13.0±0.7%); on the other hand, the first player UCT is far superior to RAVE (99.9±0.1%).

Titanium carbide (TiC) powders are successfully synthesized by carburization of titanium hydride (TiH2) powders. The TiH2 powders with size lower than 45 μm (-325 Mesh) are optimally produced by the hydrogenation process, and are mixed with graphite powder by ball milling. The mixtures are then heat-treated in an Ar atmosphere at 800-1200oC for carburization to occur. It has been experimentally and thermodynamically determined that the dehydrogenation, “TiH2 = Ti + H2”, and carburization, “Ti + C = TiC”, occur simultaneously over the reaction temperature range. The unreacted graphite content (free carbon) in each product is precisely measured by acid dissolution and by the filtering method, and it is possible to conclude that the maximal carbon stoichiometry of TiC0.94 is accomplished at 1200oC.

Go is an extremely complex strategic board game despite its simple rules and is the great challenging classic game for AI due to its enormous search space. The computer program AlphaGo finally defeated Fan Hui, the European Go champion, without handicaps on a full-sized 19 ×19 board in October 2015. Monte-Carlo Tree Search (MCTS) is a widely-used algorithm for game-tree search in game playing. MCTS based on statistical sampling is a best-first tree search technique to evaluate states; UCT which is a variant of MCTS uses the UCB1 formula as selection policy. In this paper, we evaluate the performance of MCTS and UCT playing against each other in the game of Tic-Tac-Toe. The experimental results show that the first player UCT is slightly superior to the second player MCTS (54.3±1.0%), the first player is always advantageous to the second player regardless of the MCTS and UCT players, and the result of each game should be a tie if both players do their best in Tic-Tac-Toe.

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.

Go is an extremely complex strategic board game despite its simple rules. Recently computer Go based on MCTS plays at human-master level and also has defeated top professional players with handicap games in 19×19 Go. Before implementing computer Go, in this paper we show weakness of pure MC algorithm for playing robust Tic-Tac-Toe game and present alternative method to make up the weakness. Furthermore we show how UCB algorithm works for balancing exploration and exploitation in game tree and discuss the need of a hybrid algorithm combined with UCB and strategy based MCTS, for implementing an enhanced computer Go.

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.

Evolutionary computation is a powerful tool for developing computer games. Back-propagation neural network(BPNN) was proved to be a universal approximator and genetic algorithm(GA) a global searcher. The game of Tic-Tac-Toe, also known as Naughts and Crosses, is often used as a test bed for testing new AI algorithms. We tried to recognize the strategic fitness of a finished Tic-Tac-Toe game when the parameters, such as a sequence of moves, its game depth and result, are provided. To implement this, we've constructed an evolutionary model using GA with back-propagation NNs(GANN). The experimental results revealed that GANN, in the very long training time, converges very slowly; however, performance of recognizing the strategic fitness does not meet we expected and, further, increase of the population size does not significantly contribute to the performance of GANN.

TiH2 nanopowder was made by high energy ball milling. The milled TiH2 and CNT powders were then simultaneously synthesized and consolidated using pulsed current activated sintering (PCAS) within one minute under an applied pressure of 80 MPa. The milling did not induce any reaction between the constituent powders. Meanwhile, PCAS of the TiH2-CNT mixture produced a Ti-TiC composite according to the reaction (0.92TiH2 + 0.08CNT→0.84Ti + 0.08TiC + 0.92H2, 0.84TiH2 + 0.16CNT→0.68Ti + 0.16TiC + 0.84H2). Highly dense nanocrystalline Ti-TiC composites with a relative density of up to 99.7% were obtained. The hardness and fracture toughness of the dense Ti-8 mole% TiC and Ti-16 mole% TiC produced by PCAS were also investigated. The hardness of the Ti-8 mole% TiC and Ti-16 mole% TiC composites was higher than that of Ti. The hardness value of the Ti-16 mole% TiC composite was higher than that of the Ti-8 mole% TiC composite without a decrease in fracture toughness.

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 game of Go is an oriental strategic board game originated from China at least more than 2,500 years ago. The Monte-Carlo Tree Search (MCTS) algorithm in Go is a method that uses a large number of simulations to approximately estimate the winning rate of candidate moves by sampling the game. The two computer Go programs called Crazy Stone and Mogo defeated human Go professionals on the 9⨯9 board in 2006. Prior to our implementing MCTS into computer Go, we tried to find out the best move sequence in playing Tic-Tac-Toe game as a test bed. The experimental results revealed that the first player should play the center to ensure the highest winning rate, and the game result becomes a draw if two players do their best.

TiC-21mol% Mo solid solution (δ-phase) and TiC-99 mol% Mo solid solution (β-phase), and TiC-(80~90)mol%Mo hypo-eutectic composite were deformed by compression in a temperature range from room to 2300 K and in a strain raterange from 4.9×10−5 to 6.9×10−3/s. The deformation behaviors of the composites were analyzed from the strengths of theδ- and β-phases. It was found that the high strength of the eutectic composite is due primarily to solution hardening of TiCby Mo, and that the δ-phase undergoes an appreciable plastic deformation at and above 1420 K even at 0.2% plastic strainof the composite. The yield strength of the three kinds of phase up to 1420 K is quantitatively explained by the rule of mixture,where internal stresses introduced by plastic deformation are taken into account. Above 1420 K, however, the calculated yieldstrength was considerably larger than the measured strength. The yield stress of β-phase was much larger than that of pure TiC.A good linear relationship was held between the yield stress and the plastic strain rate in a double-logarithmic plot. Thedeformation behavior in δ-phase was different among the three temperature ranges tested, i.e., low, intermediate and high. Atan intermediate temperature, no yield drop occurred, and from the beginning the work hardening level was high. At the testedtemperature, a good linear relationship was held in the double logarithmic plot of the yield stress against the plastic strain rate.The strain rate dependence of the yield stress was very weak up to 1273 K in the hypo-eutectic composite, but it becamestronger as the temperature rose.

In order to clarify the effect of Nb addition on the ductile-brittle transition property of sintered TiC, TiC-10 mol% Nb composites were researched using a three-point bending test at temperatures from room temperature to 2020 K, and the fracture surface was observed by scanning electron microscopy. It was found that the Nb addition decreases the ductile-brittle transition temperature of sintered TiC by 300 K and increases the ductility. The room temperature bending strength was maintained at up to 1800 K, but drastically dropped at higher temperatures in pure TiC. The strength increased moderately to a value of 320MPa at 1600 K in TiC-10 mol% Nb composites, which is 40% of the room temperature strength. Pores were observed in both the grains and the grain boundaries. It can be seen that, as Nb was added, the size of the grain decreased. The ductile-brittle transition temperature in TiC-10 mol% Nb composites was determined to be 1550 K. Above 1970 K, yieldpoint behavior was observed. When the grain boundary and cleavage strengths exceed the yield strength, plastic deformation is observed at about the same stress level in bending as in compression. The effect of Nb addition is discussed from the viewpoint of ability for plastic deformation.

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.

In order to clarify the effect of C/Ti atom ratios(χ) on the deformation behavior of TiCχ at high temperature, singlecrystals having a wide range of χ, from 0.56 to 0.96, were deformed by compression test in a temperature range of 1183~2273Kand in a strain rate range of 1.9×10−4~5.9×10−3s−1. Before testing, TiCχ single crystals were grown by the FZ method ina He atmosphere of 0.3MPa. The concentrations of combined carbon were determined by chemical analysis and the latticeparameters by the X-ray powder diffraction technique. It was found that the high temperature deformation behavior observedis the χ-less dependent type, including the work softening phenomenon, the critical resolved shear stress, the transitiontemperature where the deformation mechanism changes, the stress exponent of strain rate and activation energy for deformation.The shape of stress-strain curves of TiC0.96, TiC0.85 and TiC0.56 is seen to be less dependent on χ, the work hardening rate afterthe softening is slightly higher in TiC0.96 than in TiC0.85 and TiC0.56. As χ decreases the work softening becomes less evidentand the transition temperature where the work softening disappears, shifts to a lower temperature. The τc decreasesmonotonously with decreasing χ in a range of χ from 0.86 to 0.96. The transition temperature where the deformationmechanism changes shifts to a lower temperature as χ decreases. The activation energy for deformation in the low temperatureregion also decreased monotonously as χ decreased. The deformation in this temperature region is thought to be governed bythe Peierls mechanism.

In order to determine the wear properties of CVD ceramic coatings, wear process was evaluated using the coated pin of Falex Tribosystem. Also, in order to determine the effects of coating material on wear process, TiC,N of thickness 5m∼6m coated by Thermal CVD method were applied. The wear property of TiC,N film, the higher the deposition temperature was, the closer the lattice parameter was to the amount of the standard power, and the grain size increased. According to the wear formation, under the control that there is on specific wear rate wear parameter and coating delamination, decrease with increasing sliding friction and when the coating delamination happened.