Friction and Wear Behavior of Chromium Carbide Coatings

摘要

Chromium carbides, tungsten carbide, and chromium oxide have been tested and evaluated as coatings to protect high-temperature gas-cooled reactor (HTGR) steam generator and other HTGR components from adhesion, galling associated with sliding wear or from fretting. Tests were performed in commercially-pure helium and in helium doped with various gaseous impurities (H sub 2 , H sub 2 O, CH sub 4 , CO) to simulate the primary coolant of an HTGR. Several types of chromium carbide coatings including Cr sub 3 C sub 2 , Cr sub 7 C sub 3 , and Cr sub 23 C sub 6 , were tested for wear resistance and resistance to long-term spalling. Tungsten carbide and chromium oxide coatings were tested in sliding wear tests. Cr sub 23 C sub 6 -NiCr coatings showed the best performance (from 400 to 816 sup 0 C) whether they were applied by detonation gun or plasma gun spraying methods. The presence of the Cr sub 23 C sub 6 -NiCr coatings did not affect the creep rupture properties of Alloy 800H substrates at temperatures up to 760 sup 0 C. Low-cycle fatigue life of similar specimens at 593 sup 0 C was reduced to 10 to 20% when tested in the 1 to 0.6% strain range. (ERA citation 12:033178)