The high temperature corrosion resistance of NI alloy is very important in industry. For example, they have very good oxidation resistance, which is superior to iron-based and cobalt based alloys.
High-temperature corrosion forms include oxidation, carbonation, metal powder, vulcanization, nitriding, halogen corrosion and molten salt corrosion.
The results show that the degree of oxidation erosion will become more and more serious with the increase of temperature. When the temperature is higher than 980 ℃, the volatile CrO3 is formed, and the protection performance of Cr2O3 oxide layer decreases. The temperature periodically drops to room temperature and has a significant effect on the degree of oxidative erosion, as the oxide peel can cause spalling.
Carbonation refers to the presence of carbon-containing gases such as CO,CO2,CH4 and other hydrocarbons, in which carbon invades into the metal and forms carbide elements in various forms. Carbonization and other high-temperature corrosion, the formation of internal carbide will lead to metal deterioration, embrittlement and even rupture.
If the processing conditions change between carbonation and oxidation, the chromium in the alloy will be oxidized and carbonized.