Tribological study on cast iron based, graphite and CNT enriched hybrid HVOF coating from room temperature to 300°C

ABSTRACTIn this article, eco-friendly graphite has been produced from the carbonised rice husk, an environmental waste. Graphite, carbon nanotube (CNT) and cast iron powder were blended to produce the hybrid coating material. This hybrid coating material was deposited over the cast iron substrate using HVOF thermal spray. The microhardness of the coated sample increased by 42% as compared to the substrate. The morphological and elemental analysis was carried out using SEM, XRD and raman spectroscopy. The residual stresses developed in the coated sample were measured using an X-ray analyzer and found to be compressive, indicating a stable coating. A tribological investigation was carried out on a Pin-on-disc tribometer at ambient, 150°C, and 300°C temperatures. The coefficient of friction and specific wear rate reduced by ≈ 62% and ≈ 47% respectively. The SEM investigation showed evidence of free graphite as a solid lubricant over the coated samples.KEYWORDS: HVOF thermal spray coatingTribologySEMXRDResidual stressRaman spectroscopy AcknowledgementsThe authors would like to sincerely thank Metallizing Equipments Co. Pvt. Ltd., Jodhpur, for their support in sample preparation. The authors would also like to thank the management and staff of the Precision Manufacturing Laboratory, DTU, Delhi, and Tribology Centre, NIT, Srinagar for providing the tribological testing and material characterisation facilities.Disclosure statementNo potential conflict of interest was reported by the author(s).Author ContributionsSonia Dangi: Conceptualisation, data acquisition, drafting, reviewing, and editing the manuscript (First Author). R S Walia: Conceptualisation, review, and editing the manuscript (Co-Author). N M Suri: Conceptualisation, review, and editing the manuscript (Co-Author). Sumit Chaudhary: Conceptualisation, data acquisition, review, and editing the manuscript (Co-Author and corresponding author).