Silicon Nitride Applications in Modern Diesel Engines

The need for more efficient diesel engines combined with increasingly stringent emissions standards have resulted in increased cylinder operating pressures and fuel injection pressures. These conditions result in higher contact stresses in key components, which can result in wear, galling, micro-welding and finally failure of metal components. New material options are required to solve these problems.

Silicon nitride has unique tribological and physical properties (low mass combined with high strength and contact fatigue resistance) that allow its use under high contact stresses. Selection of appropriate grade of silicon nitride can solve problems in the valve train and the fuel delivery systems for light and heavy-duty diesel engines.

Silicon nitride components produced by Ceradyne are currently in production for the following applications:

• Cam Roller for Unit Injector Fuel Pumps for Class 8 Diesel Engines
• Cam Rollers for Intake and Exhaust Valves for Class 8 Diesel Engines
• Rollers for Common Rail, High Pressure Fuel Pumps for Light Duty Diesel Engines, as well as very Large Diesel Engines.

Silicon nitride has been demonstrated to be a cost effective material solution that has eliminated wear and galling of the cam rollers and the adjoining cam lobe or pump rollers and the adjoining metal components. The use of silicon nitride components has eliminated warranty problems in these applications and has resulted in increased engine reliability.