The most common configuration for a Hybrid Bearing is Silicon Nitride Si3N4 balls with either chrome or stainless steel rings. Compared to traditional steel balls, Si3N4 balls have the following desirable characteristics:
lightweight: approximately 60% lighter than bearing steel
higher hardness: over 75 HRc
stiffer: higher elastic modulus
higher maximum operating temperature: 1000+°C
lower friction: highly polished surface finish
Another popular hybrid configuration is with zirconia ZrO2 balls instead of silicon nitride. The mechanical and thermal properties of ZrO2 are closer to that of alloy steel, which can be desirable in maintaining the bearing preload and contact angle over a broad range of operating temperatures. Consult an AST Applications Engineer for a full analysis of the operating conditions and potential failure modes.