モリブデン－クロム系窒化物焼結体の耐酸化性および耐食性

抄録

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%).