Study on high temperature oxidation resistance of molybdenum and its alloys
Molybdenum is a refractory metal. Key and its alloys are widely used in aerospace, defense and military industry, electronic and electrical, metallurgy and glass industry due to their excellent electrical conductivity, thermal conductivity, corrosion resistance, low thermal expansion coefficient, high hardness and high temperature strength. However, molybdenum begins to oxidize at 400 C in the air, which makes its performance decline; when it is oxidized above 725 C, the resulting MoO3 volatilizes rapidly and forms white smoke, and the oxidation intensifies with the increase of temperature. Therefore, it is very important to study and improve the high temperature oxidation resistance of molybdenum and its alloys for expanding their application in the field of materials.
At present, the research on high temperature oxidation resistance of key and molybdenum alloys mainly focuses on two aspects: (1) alloying. The key and molybdenum alloys were modified by alloying technology to improve their oxidation resistance; (2) surface coating. A layer of anti-oxidation coating was formed on the surface of molybdenum and molybdenum alloy to make it have the ability of oxidation resistance. Alloying can improve the oxidation resistance of key and key alloy to a certain extent, but on the one hand, the degree of alloying is small, on the other hand, alloying technology will change the properties of aluminum alloy to a certain extent, so the alloying method has certain limitations. In contrast, the surface coating method can improve the high temperature oxidation resistance of the key and its alloy while maintaining the relevant properties. The intermetallic compound MoSiz is considered to be the most suitable for engineering applications because of its excellent high temperature oxidation resistance due to the formation of a dense SiO2 protective film on its surface at high temperature
The high temperature coating material (4) has also become the preferred material for oxidation resistance coating on molybdenum alloy surface.
