Thermal stability of Ir–Re coatings annealed in oxygen-containing atmospheres

• Published in: Surface & coatings technology 2013-12, Vol.237, p.105-111
• Main Authors: Liu, Shih-Chang, Chen, Yung-I, Tsai, Hung-Yin, Lin, Kuo-Cheng, Chen, Yung-Hsing
• Format: Article
• Language: English
• Subjects: Annealing; Applied sciences; Atmospheres; Coatings; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Glass; Glass molding; Ir–Re; Mass production; Materials science; Metals. Metallurgy; Molding (process); Oxidation; Physics; Production techniques; Protective coatings; Surface treatment; Surface treatments; Thermal stability
• ISSN: 0257-8972; 1879-3347
• DOI: 10.1016/j.surfcoat.2013.06.042

Ir–Re coatings are widely applied as protective coatings on glass molding dies. Because the glass molding process in mass production is conducted in an oxygen-containing atmosphere at a high temperature, the protective coatings must endure cyclic annealing treatments. Oxidation and thermal stability of Ir–Re coatings has received scant attention. In this study, Ir–Re coatings were prepared using co-sputtering. Constant-temperature annealing treatments were conducted at 600°C under a 1% O2–Ar atmosphere, which is an oxidation-accelerating atmosphere. The thermal cyclic test was performed at 270 and 600°C under atmospheres of 1% O2–Ar and 15ppm O2–N2, respectively. The 15ppm O2–N2 atmosphere is glass molding atmosphere suitable for mass production. The variations in crystalline structure, nanohardness, surface roughness, and residual stress after various annealing treatments were investigated. The more elevated Ir content coating, namely, Ir0.77Re0.23, displays superior thermal stability compared with the lower Ir content coating, namely, Ir0.53Re0.47. •Residual stress variation of coatings after thermal cyclic annealing was tracked.•Crack or pore formation after annealing resulted in coating failure.•Ir0.77Re0.23 coatings behaved superior thermal stability than Ir0.53Re0.47 coatings.