Friction and wear of electroless NiP and NiPÂ +Â PTFE coatings

In the past 30 years, electroless nickel (EN) plating has grown to such proportions that these coatings are now found underground, in outer space, and in a myriad of areas in between. The first criteria to use electroless nickel generally falls within the following categories: corrosion and wear resistance, hardness, lubricity, uniformity of deposit regardless of geometries, solderability and bondability and nonmagnetic properties. An important property is the amorphous structure in the as-plated condition and the ability to heat treat the deposit by precipitation hardening. Moreover, in order to improve the mechanical and tribological properties of the EN coatings (NiP) further, a EN-polytetrafluoroethylene (NiP + PTFE) composite coating can be obtained that provides even greater lubricity than that which naturally occurs in the nickel-phosphorous alloy deposit. The aim of the present work was an investigation of the friction and wear characteristics of NiP and NiP + PTFE coatings in sliding contacts against hard chromium steel. The role of heat treatment of the coating is discussed.