Wear Properties of Al/MoS۲ Nanocomposite Coatings Created by Electro Spark Deposition on the Surface of Ti-۶Al-۴V Alloy

This study investigates the synthesis of Al/MoS۲ nanocomposite coating by the electro spark deposition (ESD) method for its lubricating properties. ESD method was selected because it is a very easy, rapid, and cost-saving method and the resulting coating has a strong bonding with the substrate. As a substrate, a Ti-۶Al-۴V alloy sheet containing ۶.۱۲ % Al, ۴.۰۶ % V, ۰.۱۹% Fe, and ۰.۰۵ % Ni was used. For coating, an aluminum-molybdenum disulfide composite electrode in the form of a cylindrical rod was employed. Three frequencies of ۵, ۸, and ۱۱ kHz, three current limits of ۱۵, ۲۵, and ۳۵ amps, and three duty cycles of ۵۰, ۶۰, and ۷۰% were used in the coating operation. AFM analysis was used to study the topography, morphology, and calculate roughness. The samples were then subjected to hardness tests. To determine the wear resistance of the samples, pin on disk tests were performed. XRD analysis was performed to identify the phases on the surface of the coated samples. SEM was used to examine the microstructure of the coating before and after wear testing, in order to determine the wear mechanism. The results indicated that the Al/MoS۲ nanocomposite coating was synthesized on the substrate surface. The hardness of the reference sample is ۳۵۳ Vickers, and that of the coated samples is about ۲۰۰ Vickers. For the reference sample, the roughness was measured at ۱۵.۷ nm, and for the coated sample at ۲۶۸.۱ nm. As spark energy increased, the coefficient of friction increased by approximately ۰.۰۹. As spark energy increased, the wear rate increased by ۲۷%. A significant increase in the Lancaster coefficient occurred around ۵ joules of energy. According to the wear rate results, the sample with the lowest thickness wears ۴% less than the sample with the highest thickness. The wear rate of sample ۳۵۱۱۷۰ is ۷۸% lower than that of sample ۱۵۰۵۵۰.

Keywords:

Al/MoS۲ nanocomposite coating , electro spark deposition , wear properties , Synthesis