(1) The chemical reaction between atmosphere and steel
1. Oxidation
2Fe+O2→2FeO
Fe+H2O→FeO+H2
FeC+CO2→Fe+2CO
2. Restore
FeO+H2→Fe+H2O FeO+CO→Fe+O2
3. Carburizing
2CO→[C]+CO2
CH4→[C]+2H2
Fe+[C]→FeC
4. Nitriding
2NH3→2[N]+3H2
Fe+[N]→FeN
(2) The effect of various atmospheres on metals
Nitrogen: will react with Cr, CO, Al.Ti at ≥1000℃
Hydrogen: can reduce copper, nickel, iron and tungsten. When the water content in hydrogen reaches 0.2-0.3%, it will decarburize steel
Water: When ≥800℃, it will oxidize and decarburize iron and steel without reacting with copper
Carbon monoxide: its reducibility is similar to hydrogen, which can carburize steel
(3). The influence of various atmospheres on resistor components
Nickel chromium wire, iron chromium aluminum: sulfur-containing atmosphere is harmful to resistance wire