This paper describe the metal-to-ceramic joining method which is important for building ceramic adiabatic engine and deals with the potential of pistons for use for adiabatic ceramic engine.
Although various ceramic-to-metal joining methods have been developed, the chemical bonding method such as brazing and diffusion bonding is not only inferior in complex joining process and heat resistance, but also incapable of attaining the bonding strength of 196Mpa required of engineering ceramics.
The ceramic-to-metal bonding attained generally by mechanical method such as staking results in the failure of ceramic bonding face due to a strong shearing force accompanied by the plastic deformation of metal. Therefore, the reduction of the shearing force between the ceramic and metal materials and the improvement of plasticity of the metal are necessary. In this bonding method, after contact between the ceramic and metal, the metal hardness is reduced by an instant heat application to make the metal malleable whereby the metal will be formed in the shape of the ceramic by external force. It is anticipated that the bonding strength will be further improved by providing the ceramic bonding face with grooves. This bonding method offers the features of eliminating the need for selection of ceramic materials, shortening bonding time and being highly durable at a high temperatures.
The ceramic adiabatic piston produced by the above method uses the ceramic materials only for the piston head in direct contact with combustion gases and the skirt is made of an inexpensive, tough metal and the piston head and skirt are joined with a high performance heat insulating material interposed between them. Thus, a ceramic piston which is very simple, fully durable and heat insulating has been realized.