To enable a sufficient escape of heat generating in the combustion chamber in an engine along a piston piston by using the material made of silicon nitride having a specified heat conductivity at room temp.
Sintering assiting agent is added to silicon nitride powder and they are mixed and crushed by a wet type ball mill with the addition of ethanol thereto. After the application of a drying step thereto by use of spray dryer in the air for forming particles, rubber press is applied to provide a disc shaped compact and rectangular parallelopiped compact. These compact bodies are then baked by use of gas pressure furnace of graphite resistance heating type, and the obtained sintered compact is substantilly composed of only β-Si3N4. In the case of piston having the heat conductivity of 80W/(m.k) or above, the heat generating in the combustion chamber of engine escapes sufficiently along the piston pin, and thus heat is less ape to remain in the ring groove part of piston and the maximum temp. at the bottom of the ring groove becomes low. Resultantly, no sticking nor seizure wear takes place at the ring groove part.
HIROSAKI NAOTO
OKAMOTO YUSUKE
AKIMUNE YOSHIO
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