The loss of energy due to friction associated with the movement of mechanical assembly parts (MMAP) is a fundamental problem in industrial applications. The problem is not only related to the presence of friction but also to the occurrence of mechanical wear, which reduces the service time for the used parts and the need to replace them, and thus the consumption and loss of time for business owners. The primary energy loss due to friction has been estimated to be 30%, and the corresponding financial loss has been evaluated to be in billions . For this reason, we thought of producing self-lubricating materials resisting repeated mechanical loss of parts that results from insufficient lubrication, especially in harsh friction conditions that lubricating fluids are not suitable for it. In order to produce self-lubricating materials, metallic, ceramic, or plastic matrix materials have been used. The most common metallic materials used in this application are copper, silver, gold, lead, tin, and platinum. Since copper has high flexibility that makes it easy to form and has high thermal conductivity, it is widely used in such applications. Nevertheless, copper suffers from poor mechanical wear resistance. Copper matrix composites reinforced with solid lubricants such as graphite, MoS2, WS2 have been widely used as self-lubricating in many applications such as bearings and bushings for their low friction coefficient and high wear-resistant properties [2–6]. Molybdenum disulfide is a solid lubricant material. It is similar in its structure to graphite, as it consists of flakes whose atoms Mo and S are linked with a covalent bond, which indicates the strength of the contact between them, as is the case in graphene layers. The MoS2 can provide lubrication for moving parts such as graphite, especially in a vacuum and dry gas environment. It has a lamellar structure such as graphite formed by many stacked layers. Each MoS2 layer is composed of a plane of molybdenum embedded between two planes of sulfur atoms by the covalent bonds. Therefore, the strength of every single layer is high as graphene [7–8]. Some studies on copper metal matrix composites strengthened with MoS2 were performed to improve its tribological performance. Reinforcing the copper matrix with 10 wt% MoS2 increased the hardness to 89HV with a 32.83% increment. The wear rate dramatically decreased from 0.04 to 0.02 g, and the coefficient of friction reduced to 0.32 µm . Jin-Kun Xiao et al.  investigated the tribological behavior of Cu- MoS2 composites. The results confirmed that MoS2 addition was an effective lubricant for copper matrix composites against steel. The friction coefficient decreased from 0.67 to 0.18 when 20 vol% of the MoS2 was added. The wear rate of the composites tended to increase at low percentages then reduced as the MoS2 content increased. Researchers have been tried to improve the properties of the copper-based self-lubricating materials by reinforcing them with ceramic materials such as Al2O3, TiC, WC or SiC [11–16]. The presence of ceramic particles in the matrix (bushings) leads to destroying the surface of the shaft (the protected parts) through scratching it. The authors suggested coating the ceramic particles with MoS2 layers to solve the mentioned problem. Coating the alumina particles by the molybdenum disulfide flakes will cover the sharp edges and reduce their surface roughness and, consequently, the coefficient of friction and mechanical wear. From the authors' point of view, this will improve the strength and resistance of the materials to erosion and thus increase their service life. In addition, maintaining the essential parts required to be protected from mechanical wear (shaft or machine frame).
In this paper author aimed to take advantage of molybdenum disulfide flakes in strengthening copper composites to reduce both the rate of mechanical wear and the coefficient of friction. Farther increase the life of copper composites that are used as self-lubricating bushings. The effect of coating alumina particles with layers of molybdenum disulfide on the microstructure, densification, hardness, mechanical wear, and coefficient of friction of the copper matrix have been studied for applications of self-lubricating applications.