PURPOSE: To easily obtain a composite ceramic material having high strength and heat-insulation by closely bonding a ceramic composed of specific elements and containing prescribed amount of pores to a piston head made of a dense ceramic material.
CONSTITUTION: The upper space of a head case 2 of a piston head made of a dense ceramic material is filled with a ceramic material composed of all of the elements Si, N and O and at least one kind of elements of Ti, Zr, Hb, Y, B and Al and containing ≥12% pores. The pore-containing ceramic is closely bonded to the piston head made of the dense ceramic material. Since an oxide composite reaction sintered ceramic is used in place of aluminum titanate for filling the top space of the above head, the strength of the present head is three times as high as the conventional heads and the thermal conductivity is maintained to a level comparable to that of the conventional heads. The reliability of the part to be used in a place subjected to severe heat-cycle can be improved by this process.