Wear-resistant coating for rotary engine side housing and method of making

Abstract

Abstract An improved wear-resistant surface preparation is used on the inner side walls of the combustion chamber of a rotary piston engine. The improvement comprises deposition of two distinct but admixed metallic powders of generally equal hardness; one of the powders contains fluxing agents which enable the deposited powders to self-sinter if deposited in a semiplastic condition. The powders are deposited on a previously undercut cast iron side-housing. The resulting coating composition is characterized by minimum hardness value of Rc 30 at elevated operating temperatures of 400*F. The composition retains a stable hardness at elevated temperature levels up to 1100*F. The coating may have a porosity of 3-9%, but particle size is controlled to limit the porosity to 5% which is compatible with lubricating requirements of a rotary engine. The coating composition is deposited across the entire area circumscribed by the path of the outer most side point of the apex seals carried by the rotary piston; the path is substantially commensurate or approaches the entire shape of the epitrochoid chamber. The coating is compatible with the composition of the rotor side seals, oil seals and corner seals bearing thereagainst. The rotor side seals are comprised of cast iron, the oil seals are cast iron coated with limited chromium, the corner seals are prepared from cast iron, and the apex seals are strips of metal coated with an alloy of iron and titanium carbide with graphite. A method is disclosed comprising: (1) machining a cast side housing structure to a depth sufficient to accommodate a slightly oversized finish coating. The cast structure is undercut, grit blasted and preheated to 200*F., (2) a coating of admixed martensitic stainless steel and an equally hard nickel-based alloy is flame sprayed upon the machined area including approximately three-eights of an inch margin beyond the undercut area, the spraying being conducted by rotating the surface to be sprayed along with radial and rotative movement of the spray gun arranged to direct the spray perpendicular to the surface, (3) soaking the flame sprayed coating immediately after deposition with oil, and (4) grinding the surface finish to a predetermined reference thickness.

Inventors

• 👤 Yeshwant P Telang
• 👤 James C Uy

Bibliographic Details