Material Properties and Microscopic Mechanisms
· Corrosion Resistance:
· Sulfate Passivation: Added Cu (3%) promotes the formation of dense oxide films (e.g., CuO/Cu₂O) in low-concentration sulfuric acid (H₂SO₄), enhancing corrosion resistance.
· Chloride Resistance: Mo (3%) forms stable MoOCl₄²⁻ complexes with Cl⁻ ions, preventing chloride penetration and mitigating pitting/sress corrosion cracking (SCC).
· High-Temperature Oxidation: Mo forms a continuous (Ni,Mo)O phase with a melting point up to 1600°C, maintaining oxide film stability at 300–500°C.
· Sulfur Resistance and Lubricity:
· Mo-S Interactions: In sulfur-containing environments, Mo reacts with S to form molybdenum disulfide (MoS₂), a lamellar structure that reduces friction coefficients (0.05–0.1) and acts as a solid lubricant.
· Dynamic Load Endurance: MoS₂ softens under frictional heat, forming a transfer film that extends service life in dynamic friction applications.