Abstract
This paper describes a feature of developed high-strength Si3N4 ceramics and its application for automotive engine parts. By the high speed shock compression test, Hugoniot elastic limit of various Si3N4 ceramics were evaluated. The microstructure of developed Si3N4 is controlled with the linear density of Si3N4 crystalline grains shows the superior mechanical properties compared to the conventional Si3N4. [It has JIS 3-point bending strength : 1600-1800 MPa; Charpy impact value : 14-16 kJ/m2.] The developed Si3N4 powertrain part as a adjusting shim with a mirror-finished surface has been evaluated by the motoring apparatus about the fracture behavior during the valve bouncing and the friction torque of a cam shaft. The result shows that about 50% higher shock resistance of developed Si3N4 shim and 10-20% reduction of friction torque. By using the shims, 2-3% improvement ratio of fuel-consumption has been proved by the actual driving test.
