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随着科学技术的发展,要求在大气中精确测量和控制2000℃以上的高温。众所周知,铂族金属是最抗氧化的。但熔点在2000℃以上的铂族元素只有铱(2447℃)、钌(2255℃)和锇(3006℃)。由于锇和钌,特别是锇性质很脆,无法加工成丝,不能单独作热电偶材料使用,而仅仅用作添加元素。由于这两种金属均较易氧化蒸发,在空气中使用也受到一定限制。因此,实际上可考虑的唯一元素就是铱。
With the development of science and technology, it is required to accurately measure and control the temperature above 2000 ℃ in the atmosphere. It is well-known that PGMs are the most resistant to oxidation. However, platinum group elements having a melting point above 2000 ° C only include iridium (2447 ° C), ruthenium (2255 ° C) and osmium (3006 ° C). Since osmium and ruthenium, especially osmium, are so brittle that they can not be processed into filaments, they can not be used as thermocouple materials alone, but merely as additive elements. As these two metals are more prone to oxidative evaporation, the use of air is also subject to certain restrictions. Therefore, the only element that is actually considered is iridium.