Low frictional ceramic materials

摘要

This paper describes the development of new Si{sub}3N{sub}4 ceramics with both low friction coefficient and high strength, aiming at the reduction of friction force between cylinder liner and piston ring in low heat rejection engine. Si{sub}3N{sub}4 ceramics has high Young's modulus, therefore, it provides lower coefficient of friction than iron. We thought that if adsorption ability of Si{sub}3N{sub}4 to lubricant oil were improved, coefficient of friction got still lower. In order to achieve this Fe{sub}3O{sub}4, which has superior adsorption ability, was used as one of additives for Si{sub}3N{sub}4. The obtained new Si{sub}3N{sub}4 had obviously lower coefficient of friction than conventional Si{sub}3N{sub}4 and its strength was almost the same as conventional Si{sub}3N{sub}4. Moreover, cylinder liner and piston ring were fabricated from developed Si{sub}3N{sub}4. They were tested using engine and reduction of friction force was confirmed.