M 5165 (OTTO) Molybdenum, irregular particles, <30 mm, 99.8% Cas 7439-98-7 - used in steel alloys, including high-strength alloys and superalloys. M 5165 (OTTO) Molybdenum, irregular particles, <30mm, 99.8% Cas 7439-98-7 - used to blacken a surface or as a solid lubricant.