High temperature tribological and electrochemical behavior of heat-treated Al2O3-base hybrid coating sprayed by HVOF thermal spray technique

• Published in: Materials research express Vol. 10; no. 2; pp. 026402 - 26414
• Main Authors: Sonia, Walia, R S, Suri, N M, Chaudhary, Sumit
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 01-02-2023
• Subjects: Abrasion; Aluminum oxide; anti-corrosive; Cast iron; Coating; Coefficient of friction; Corrosion prevention; Electrochemical analysis; Heat treatment; High temperature; high-temperature tribology; HVOF; Mathematical analysis; micro-hardness; Microhardness; Phase composition; Plastic deformation; Protective coatings; Raman spectroscopy; Residual stress; Silica fume; Substrates; Tribology; Wear rate
• ISSN: 2053-1591
• DOI: 10.1088/2053-1591/ac84c7

In the present study, the hybrid coating was developed by HVOF over the cast iron substrate. The hybrid coating material comprises Al2O3 (80% w/w) enriched with graphite, MoS2, and fumed silica in w/w of 5%, 10%, and 5% respectively. Microstructure and phase composition of prepared coated samples were analyzed by SEM-EDS, XRD and Raman Spectroscopy. The coated samples were heat-treated and their mechanical, electrochemical and tribological behavior was compared with the as-coated samples. There was a considerable change observed in the micro-hardness and anti-corrosion properties of the coated material after heat treatment. The residual stresses in the heat-treated sample decreased compared to the as-coated sample. The high-temperature tribological investigation was carried out in non-lubricated conditions at three different temperatures 30 °C, 150 °C, and 300 °C with a constant load of 40 N and variable sliding speed. The coefficient of friction and wear rate was calculated and it was found that there was a decrement up to 36% in the wear rate of the heat-treated samples compared to the as-coated sample. The SEM morphologies of the wear track showed the presence of small cracks, adhesion, abrasion and smear regions due to plastic deformation.