Improvement Of Sliding Bearings Durability In Ultra Pure Water By Diamond Film

Abstract

Silicon carbide (SiC) is known for its superior abrasion resistance, and is widely used in pumps as a material for water-lubricated sliding bearings. Ultra pure water (UPW), with a specific resistance of greater than 10 Mᘯ/cm, is often used for purposes such as washing water in semiconductor manufacturing processes and recirculation water in nuclear power generation plants. However, in cases where SiC sliding bearings are lubricated with ultra pure water, abnormal wear is occasionally found. Such a problem is not seen with normal water lubrication. The abnormal wear when lubricated with UPW is caused by oxidation of the SiC surface and generation of silicon dioxide. Diamond is the hardest material in the world, and are expected to provide effective abrasion resistance. Polycrystalline diamond film is harder than SiC and can be formed by chemical vapor deposition (CVD). There are various potential applications for this material, including sliding bearings. This report describes a case study in which the durability of sliding bearings in ultra pure water was improved by forming a polycrystalline CVD diamond coating on the SiC sliding surface.