Acid Resistance

the ability of materials to resist the destructive effect of acids.

Acid resistance depends on the nature of the material, the redox properties of the medium, the nature of the anions, and the concentration and temperature of the acids. For example, chromium and chromium steels are stable in 40 percent nitric acid but undergo rapid corrosion in 40 percent sulfuric acid. The acid resistance of materials decreases with temperature. It is important to differentiate between acid resistance in liquid and vapor-gas phases and at the boundary of the two. The acid resistance of metallic materials is determined by loss of mass per unit area (9 per sq m per hr). The acid resistance of nonmetallic organic materials is gauged according to the degree of swelling and the change in mechanical properties (strength, yield point, ultimate elongation). The acid resistance of nonmetallic inorganic materials is determined by the change in mass of the pulverized material after acid treatment.