Mechanical Properties and Oxidation Resistance of Cr–W–N coatings

• Main Authors: Cheng, Yu-Ru, 鄭玉如
• Other Authors: Chen, Yung-I
• Format: Others
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/36229142676837941394

碩士 === 國立臺灣海洋大學 === 材料工程研究所 === 103 === Cr–W–N coatings with a Cr interlayer were prepared using reactive direct current magnetron co-sputtering on silicon and cemented carbide substrates. The co-sputtering process varied the individual target powers, fixed the total power at 300 W, and set the N2 flow ratio (N2/(Ar + N2)) at 0.4. The N content of the Cr–W–N coatings decreased from 47 at.% to 8 at.% as increasing the W-target power from 10 W to 290 W, which resulted in that Cr–W–N coatings exhibited various chemical compositions and crystalline characteristics. The Cr-rich Cr–W–N coatings exhibited a face-centered cubic phase, whereas the W-rich coatings exhibited a nanocrystalline phase in the as-deposited states. The as-deposited Cr8W69N23 coating exhibited a nanohardness of 27.6 GPa, accompanying with a mixture structure of face centered cubic and nanocrystalline phases. To explore the thermal stability of Cr–W–N coatings in glass molding processes, thermal cycle annealing, involving annealing at 270 °C and 600 °C and maintaining at 600 °C ± 10 °C for 1 min/cycle, was conducted in a quartz tube furnace to simulate glass molding process in a continuous flow of 15–ppm O2–N2. One commercial moldable SiO2–B2O3–BaO-based glass was used to evaluate the chemical inertness of Cr–W–N coatings in glass molding. The glass and coating assemblies were subjected to up to 1000 thermal cycles. The variations on the crystalline structure, mechanical properties, surface roughness, and Chemical inertness after various annealing durations were investigated.