Cobalt@-based alloy for dental prosthesis - contains defined amts. of carbon, manganese, silicon, nitrogen, chromium, molybdenum, tungsten and rare earth elements

摘要

A Co-based alloy has not above 0.05wt.% of C, not above 0.3% of Mn, 0.9-1.8% of Si, above 0.15% of N, 22-25% of Cr, 6.5-8% of Mo, 4-6% of W, and 0.15-0.35% of rare earths. USE/ADVANTAGE - The alloy is used to prepare crowns, bridges or cast parts, esp. by casting at 1430-1480 deg.C (claimed), in dentistry. The alloy tolerates repeated heating without deterioration of the micro-structure or affecting the strength or corrosion resistance, is biocompatible, can be etched in boiling aqua regia (1 pt. HNO3 + 3 pts. HCl), and is easily worked without needing a protective atmos. or casting in a vacuum. The coefft. of heat expansion at 25-500 deg.C is not above 14.3 x 10 power(-6) deg.K (not below 13.8 x 10 power(-6) deg.K); the alloy is esp. suitable for use with ceramics (coefft. of heat expansion about 13.7 x 10 power(-6) deg.K), giving reduced risk of cracking or displacement of the underlying metal structure in the hot/cold cycles to which dental prostheses are subjected