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贵金属包括金、银和铂族元素一铂、铑、钯、铱、钌和锇。金属状态金具有美丽的黄色,锇为蓝灰色,其余6种金属均为银白色。金的熔点1063℃,银为960.5℃。除此之外,铂族元素的熔点均较高(钌2310℃,铑1966℃,钯1554℃,锇3045℃,铱2410℃,铂1772℃)。贵金属具有优异的耐腐蚀性、抗氧化性、延展性,较高的密度和良好的生物相容性。由于贵金属独特的物理、化学和生物学性能,使它们成为首选牙科合金,在世界上得到广泛应用。1 牙科贵金属合金应用状况 约在公元前2500年,金就开始用于牙科修复。本世纪初,精密铸造技术被引入牙科修复工艺,推动了贵金属在牙科中的应用,金的消费量逐年增加。70年代,金价格上涨,促进了替代合金的出现。替代合金分为二类:一类是降低金含量,代之以钯和银的低金合金,含微量金的钯基合金(主要用
The precious metals include gold, silver and platinum group elements of platinum, rhodium, palladium, iridium, ruthenium and osmium. Metal state gold has a beautiful yellow, osmium blue gray, the remaining six kinds of metal are silver white. Gold has a melting point of 1063 ° C and silver of 960.5 ° C. In addition, the platinum group elements all have high melting points (ruthenium 2310 ° C, rhodium 1966 ° C, palladium 1554 ° C, osmium 3045 ° C, iridium 2410 ° C, platinum 1772 ° C). Precious metals have excellent corrosion resistance, oxidation resistance, ductility, high density and good biocompatibility. Due to the unique physical, chemical and biological properties of precious metals, they have become the preferred dental alloys and are widely used in the world. 1 Dental Precious Metals Alloy Applications About 2500 BC, gold began to be used for dental restoration. The beginning of this century, precision casting technology was introduced into the dental restoration process, promoting the use of precious metals in dentistry, gold consumption increased year by year. The 70s, gold prices, promoted the emergence of alternative alloys. Replacement of the alloy is divided into two categories: one is to reduce the gold content, replaced by palladium and silver low gold alloy, containing a small amount of gold palladium-based alloy (mainly used