Abstract
The oxidation characteristics in air were investigated for Mo-Cr nitrides prepared by pulsed electric current sintering (PECS) of mixed Mo2N and CrN powder, in addition to their corrosion characteristics in boiling sulfuric acid. Mo2N type solid solutions were found to be easily formed using PECS. Sintered compacts with a CrN content of >35 wt% consisted of two kinds of solid solution: Mo2N type with a Cr:Mo atomic ratio of about 1:1, and a Cr-rich phase. The solid solubility limit for Cr in Mo2N was about 50 at%. The hardness of the sintered compacts decreased with increasing CrN content, and their density increased. Although Mo2N (0 wt% CrN) was strongly oxidized at temperatures above 773 K, sintered compacts with a CrN content of >35 wt% were highly resistant to oxidation even at temperatures above 1073 K. All of the sintered compacts except that containing 100 wt% CrN exhibited perfect corrosion resistance in boiling sulfuric acid (75 wt%).
