Enhancing the durability of cast steel cylinder liners using HVOF sprayed functionally graded coatings

Abstract This study investigates the performance of high-velocity oxygen fuel (HVOF) sprayed coatings on cast steel cylinder liners, specifically focusing on the Ni-Cr, WC-Co-Cr and WC-Co powder compositions to create functionally graded material (FGM) coatings. The wear resistance, evaluated using linear reciprocating tribometer, revealed that the FGM coated sample-A (designated as FGC-A) exhibits a minimal weight loss of 0.0010 g, outperforming FGM coated sample-B (FGC-B), with 0.0019 g weight loss, and FGM coated sample-C (FGC-C), with 0.0026 g weight loss. Furthermore, the results of immersion corrosion tests, in 50% H 2 SO 4 , indicated that FGC-A had the least corrosion weight loss of 0.47%, which is significantly better than FGC-B (1.37%) and FGC-C (1.87%). These results demonstrate that FGC-A offers superior wear and corrosion resistance compared to its counterparts. An empirical model to predict the wear loss in HVOF coatings, based on process parameters, was also developed and it was observed that optimizing the parameters such as oxygen flow, kerosene flow, stand-off distance, and feed rate play vital role in enhancing the quality of the coatings. In this study, the best settings for the process were found to be an oxygen flow of 867 m min −1 , a kerosene flow of 24 liters per hour, a stand-off distance of 340 mm, and a material feed rate of 86 grams per minute. These values were identified as the most effective for achieving strong and durable coatings with improved hardness and resistance to wear.