Effect of Heat-Treatment on the Thermal and Mechanical Stability of Ni/Al₂O₃ Nanocrystalline Coatings

• Main Authors: Kavian O. Cooke, Tahir I. Khan, Muhammad Ali Shar
• Format: Article
• Language: English
• Published: MDPI AG 2020-02-01
• Series: Journal of Manufacturing and Materials Processing
• Subjects: nanocrystalline; co-electrodeposition; heat-treatment; sliding wear; grain growth
• Online Access: https://www.mdpi.com/2504-4494/4/1/17

Heat-treatment is a frequently used technique for modifying the physical and chemical properties of materials. In this study, the effect of heat-treatment on the mechanical properties, thermal stability and surface morphology of two types of electrodeposited coatings (pure-Ni and Ni/Al₂O₃) were investigated. The XRD analyses showed that the crystal structure of the as-deposited coating changes from slightly amorphous to crystalline as the heat-treatment temperature increases. The heat-treatment of both the pure-Ni and the Ni/Al₂O₃ coating caused an increase of the grain size within the coatings. However, the unreinforced Ni coating experienced a faster growth rate than the Ni/Al₂O₃ coating, which resulted in a larger average grain size. The temperature-driven changes to the microstructure of the coatings caused a reduction in the hardness and wear resistance of the coatings. The presence of nanoparticles within the Ni/Al₂O₃ coating can successfully extend the operational temperature range of the coating to 473 K by pinning grain boundaries.