Formation of Al2O3/MoS2 nanocomposite coatings by the use of electro spark deposition and oxidation

Abstract

Grade 5 titanium is the most widely used titanium alloy, but it has low tensile and shear strength. Therefore, it is expected to have a high coefficient of friction, limiting the use of this alloy. In this study, to improve the properties of grade 5 titanium, Al2O3/MoS2 nanocomposite coating was applied to it using electro spark deposition method and further oxidation of Al/MoS2 coating. The coating operation was performed in the conditions of 5, 8, and 11 kHz frequencies, 15, 25, and 35 amps current limits, and 50, 60, and 70% duty cycles. XRD and SEM analysis were used to examine the structure of the coating. Examination of the electrode showed that the electrode contained high amounts of aluminum along with molybdenum disulfide dispersed in between. The results showed that Al2O3/MoS2 nanocomposite was formed on the substrate. The calculated minimum and maximum spark energies were 0.75 and 8.63 J, respectively. The maximum spark energy is related to the duty cycle of 70%, frequency of 11 Hz, and the current limit of 35 amps. The lowest efficiency of the coating process was 14.29%, and the highest efficiency was 75.86%. The highest efficiency is related to the duty cycle of 60%, frequency of 11 Hz and current limit of 25 amps. The sample had the highest thickness with a value of 21.3 μm, and the sample had the lowest thickness with a value of 2.3 μm. The highest thickness of the coating is related to the duty cycle of 70%, frequency of 5 Hz, and the current limit of 25 amps.