Brush plating: Recent property data

Abstract

The information presented in this article provides quantitative property data on a variety of brush-plated deposits and shows that these coatings offer promise in applications involving wear and corrosion. CoMo, CoW, CoWP, NiCoZrO 2, and NiP improved wear resistance and service life of hot work dies. The CoWP alloy provided the best results. Trivalent Cr had a hardness similar to that of hexavalent tank-plated Cr and improved wear resistance in Taber tests. Cu was quite effective in preventing environmental embrittlement of iron aluminides. With 304 stainless steel, a sandwich coating of Cu and Ni inhibited stress corrosion cracking, thus indicating that this coating may be useful for field service protection against SCC and crevice corrosion at flange joints. NiCo deposits were worn to a much lesser extent than Ni or NiW in ball on disk tests. Hexavalent tank-plated Cr performed better than Ni and NiCo coatings in wear tests. Hard Ni, NiW, and CoW deposits were not deemed ready for replacement for tank-plated hexavalent Cr at Tinker Air Force Base. The tensile properties of a medium carbon steel were not markedly affected by plating with Ni, although there was some reduction in ductility; however, a marked reduction in fatigue strength was obtained. Shot peening, whether before or after brush plating, noticeably minimized the fatigue strength reduction. The weight loss in wear testing of a NiCoSiC deposit was only one third that of a Ni deposit. The SiC coating showed good results when used on ship engines. A NiFeWP deposit was noticeably more corrosion resistant in NaCl and H 2SO 4 than tank-plated Ni or hexavalent Cr. An alloy containing NiFeWS was superior to tank-plated hexavalent Cr under high load dry friction wear testing. NiP and NiCuP showed promising friction coefficients on 1045 steel. A PbSn alloy on 1017 steel noticeably reduced hydrogen permeation. An alloy containing PbSnNi exhibited a much lower friction coefficient and a better scuffing resistance than PbSn alloys.