Evaluation Of Coatings For Resistance To Abrasive And Adhesive Wear In Pump Components

Abstract

Long term pump efficiency and durability are directly related to the ability of materials of construction to resist various forms of wear. The need for resistance to both adhesive and abrasive wear is often greatest in wear rings and similar components, where close clearances must be maintained between rotating and stationary components. Insufficient resistance to adhesive wear will induce failure by galling or seizure in the event these components make contact. Inadequate resistance to abrasive wear will lead to rapid loss of clearances and drop in pump performance. Traditionally, pump manufacturers have specified hardened martensitic stainless steels for critical wear parts, maintaining a 50-100 Brinell hardness difference between rotating and stationary components as experience has shown this is adequate to prevent galling. Coatings have been used to a limited extent, primarily in specialized applications, such as the plungers in reciprocating pumps. Selection of coatings have been hampered by a lack of reliable technical data on comparative performance. The result has been that a variety of coatings have been utilized by various pump manufacturers through the years, with mixed success and few documented case histories on coating performance.