The codeposition of chromium and aluminum on nickel-based alloys by pack cementation.

摘要

Several variables of the pack cementation process were studied to determine their effect on the codeposition of chromium and aluminum on Ni270 and PWA1484. Specifically, the amount and composition of the master alloy (95Cr 5Al and 90Cr 10Al) and activator (NH;In order to elucidate the effect of the amount of master alloy and the composition of the activator, several pack compositions were studied as a function of time. The pack composition as a function of coating time and pack position relative to the sample surface was studied by vacuum impregnating the pack and sample in epoxy resin and analyzing individual particles by microprobe analysis. It was found that decreasing the amount of master alloy increases the overall rate of depletion of aluminum from the pack, which leads to an increase in chromium deposition. An aluminum depletion zone was formed adjacent to the sample at short times for all conditions studied, and was thus not a function of the pack variables studied. Use of CrCl;Three types of coatings on PWA1484, an aluminide, chromide, and codeposited, were developed and evaluated for oxidation and corrosion resistance. Two industrial coatings, PWA73 and PWA70/73, were also evaluated for comparison. The conditions studied included: high temperature cyclic oxidation at 1100