Papers by Author: Akira Terayama

Abstract: Metallic fibers (Fe-Cr-Si) with an excellent high temperature strength are expected to be use as a reinforced material of the engine piston head. However, the high reactivity of Al with most metals has disturbed the use of metallic fibers in aluminum composites until now. In this study, the influence of the reaction products at the fiber/matrix interface on high temperature properties of the composites was investigated by different solution treatment conditions. It is found that hardness and strength increase with an increase the solution treatment temperature (Tst). Reaction products (Al-Fe intermetallic compounds) resulting from solution treatments were formed along the fiber/matrix interface at 773 K or higher. The composites without interfacial reaction products (Tst=763 K) showed excellent rotating-bending fatigue life at 573 K. The fatigue crack propagation in this composite occurred at the necking region of the metal fiber because no cracks were observed in the interfacial reaction products.

Abstract: To develop the small engine used for the wireless control helicopter, a very high power density source will be required. The rotary engine (RE) is advantageous in the points such as a volume of the engine, the exhaust gas emissions, and the vibrations. In this research, in order to develop the small RE, the design of the combustion chamber was reviewed. Additionally, the method of the surface treatment of the rotor housing was investigated by the friction wear test to enable the material substitution for aluminum matrix composites. The friction wear tests of composite materials, the Cr and Ni-plated material were conducted. As a result, the sample with the most excellent abrasion resistance was the composite material reinforced with Al2O3 fibers. The wear-loss of this composite material was 1/10 compared with the Ni-plated material. This composite material formed oil pockets between the fiber and the matrix, and a friction coefficient fell below 0.1. Then, the aluminum rotor housing reinforced partially by Al2O3 fiber was fabricated using a low-pressure infiltration method. The maximum power of the small RE (1 rotor, 30 cc) which built in this housing reached about 5 PS in the range from 13,000 to 15,000 rpm. The inside of the housing used composite materials was not damaged even after 30 hours. On the other hand, the flaking off part was observed on the inside part in the case with the housing used the Ni-plated material. Additionally, the output and the torque of the RE made of composite materials were higher than those of the Ni-plated material. This was considered because the friction coefficient of composite materials was lower than that of the Ni-plated material. Finally, the small unmanned helicopter equipped with RE succeeded in a stable flight.

Abstract: In this research, we investigated the fabrication conditions of Ti-Ni alloy powder by MA process and the shape memory characteristics of the sintered alloy by a pulse-current sintering equipment using mechanically alloyed powder (MA powder). The microstructure of the sintered alloy of the MA powder was more homogeneous than that of the alloy of the elemental powders. The application of the MA powder makes the width between transformation temperatures of the shape memory treated alloy of the MA powder became narrower, that is, it improves the temperature response of the compact. The tensile strength and elongation of the shape memory compact of the MA powder were approximately 780 MPa and 7.5 %, respectively. This is one of the superior tensile properties of SMA compact fabricated by powder metallurgy process. The superelastic behavior took place in the alloy of the MA powder. Thus, the MA process in short process time resulted in lower contamination of the MA powder and the application of the MA powder resulted in superior shape memory characteristics of the sintered alloy.