The Testing of Plasma Spray Coatings

This program was conducted for the purpose of providing reference data on plasma-sprayed coatings for use in the design and repair/salvage of naval ordnance hardware. Plasma-spray deposition parameters and surface finishing techniques were developed for metal and ceramic plasma-sprayed coatings applied to mild steel, stainless steel, aluminum, brass, and K-monel. The wear characteristics of the coated shafts versus a variety of bushing materials were studied in hydraulic piston wear tests during which oil leakage rates as a function of surface finish were determined using Teflon and urethane seal materials. As a result of the program, plasma-sprayed coatings and bushing material were identified that provided friction and wear performance at least comparable to that provided by baseline conventional cylinder materials. Teflon seals were found to provide the most reliable dynamic seal performance, and a low viscosity, polyester type resin sealer (Loctite 290) was found to be an effective sealant for both hydraulic and pneumatic applications. The plasma-spray parameters and processing parameters and techniques developed in this program and information on the coating properties and process limitations derived from this work will be incorporated in the plasma-spray handbook being prepared for NOSL under Contract No. N-00197-73-C-0430. (Author)