1、 Basic corrosion resistance characteristics
1. Passivation film protection
At room temperature, a dense zirconia passivation film can be formed on the surface of zirconium plates, which self repairs in oxidizing media and has a barrier effect on most acid, alkali, and salt solutions.
Corrosion resistance to hydrochloric acid: Industrial pure zirconium ZR702 has a corrosion rate of<0.025mm/a in boiling concentration hydrochloric acid.
Excellent alkali resistance: resistant to molten alkali and boiling concentration caustic alkali solutions, with performance surpassing titanium and tantalum.
2. Medium adaptability
Nitric acid: Corrosion resistance close to platinum below 200 ℃, sensitive to stress corrosion cracking;
Sulfuric acid: High temperature dilute sulfuric acid is stable, and over 70% boiling sulfuric acid causes severe corrosion;
Hydrofluoric acid/aqua regia: completely unsuitable, 0.001% concentration can corrode perforation.
2、 Special environmental performance
1. High temperature corrosion
Long term temperature resistance upper limit: 425 ℃, beyond which the oxide film becomes loose and falls off.
Pre oxidation strengthening: Pre oxidation treatment at 1000 ℃ in air can improve initial corrosion resistance.
2. Gas corrosion
Nitrogen: Significant nitridation above 600 ℃, intense reaction at 900 ℃.
Hydrogen: Hydrogen absorption is significant at 300 ℃, and the working temperature needs to be controlled below 250 ℃.
3. Alternating corrosive environment
Suitable for strong acid strong alkali alternating working conditions, with better resistance to alternating corrosion than stainless steel and nickel based alloys.
3、 Material comparison and engineering applicability
Zirconium plate: boiling full concentration stable, ≤ 70% concentration high temperature suitable for molten alkali corrosion free, extremely low neutron absorption cross section;
Stainless steel: resistant to medium concentration room temperature alkali;
Titanium plate: resistant to dilute hydrochloric acid, resistant to low concentration sulfuric acid at room temperature, not resistant to concentrated alkali, poor radiation resistance.
4、 Empirical Study on Industrial Applications
1. Chemical containers
Used for hydrochloric acid storage tanks and sulfuric acid heat exchanger tube plates, the design life is 3-5 times longer than stainless steel.
2. Nuclear energy equipment
Zirconium niobium alloy, as a fuel cladding material, has a corrosion rate of<0.03mm/a in pure water at high temperatures of 300-400 ℃.
3. Special reactor
When dealing with acidic media containing chloride ions.
