In recent year's aluminium and aluminium alloys are widely used in automotive industries. These are light (density of about 2.7 g/cm3), having good malleability and formability, high corrosion resistance and high electrical and thermal conductivity. Metal matrix composites (MMCs) are being employed in industrial applications since they have high specific strength, stiffness, and good wear properties. Due to their favourable properties, composite materials with reinforcements are used in many industries. With the aim to additionally improve some of their properties, especially their tribological properties, several solid lubricants are used in the process of composite production. This paper gives an overview of investigations and possibilities of solid lubricant particles (such as graphite) applying as complementary material, mainly for aluminium base composites that are nowadays common in use in automotive and aeronautics industry.

The paper presents some aspects regarding the wetting conditions in aluminium – graphite composite. The wettability depends on several factors like the presence of the oxide skin at the melt surface, formation Al4C3 at the interface between Al and particles, temperature, pressure etc. In this paper, the conditions of perfect wettability of carbon by molten Al achieved under MCl–K2TiF6 molten salts (fluxes), alloying of the melt with surface active elements, heat treatment of reinforcement material and coating of the particles with a metallic thin layer.

The paper is a synthesis of essential data regarding the wetting conditions in aluminium – silicon carbide mixtures. Non wetting conditions between the reinforcing element and the matrix turns difficult the incorporation of particles in the aluminium melt. The wettability depends on several elements, like the presence of the oxide layer at the melt surface, temperature, pressure or shape of the complementary material. To improve wetting conditions, several measures are necessary: alloying of the melt with surface active elements, overheating of the melt; coating of the particles with a metallic thin layer. Also, by using existing data reported in the field, some parameters were calculated and interpreted.

Aluminium-based Metal matrix composites (MMCs) have become increasingly used for structural applications in various industrial sectors because of their excellent specific stiffness and specific strength. Discontinuously reinforced (DR) Al/SiC metal-matrix composites (MMCs) are modern, lightweight materials which have a very attractive combination of material properties and price. The use of DR Al/SiC MMCs is mostly limited to the military and aerospace, however, these materials are now beginning to penetrate civilian applications. Besides the mechanical behavior, knowledge of the corrosion resistance of DR Al/SiC MMCs is very important, and so the corrosion resistance of Al/SiC composites has been investigated and discussed in comparison with a conventional Al alloy of similar composition.