Tribology of Metal Matrix Composites

Abstract

Metal matrix composites (MMCs) are an important class of engineering materials that are increasingly replacing a number of conventional materials in the automotive, aerospace, marine, and sports industries due to their lightweight and superior mechanical properties. In MMCs, nonmetallic materials are embedded into the metals or the alloys as reinforcements to obtain a novel material with attractive engineering properties, such as improved ultimate tensile strength, ductility, toughness, and tribological behavior. In this chapter, an attempt has been made to summarize the tribological performance of various MMCs as a function of several relevant parameters. These parameters include material parameters (size, shape, volume fraction, and type of the reinforcements), mechanical parameters (normal load and sliding speed), and physical parameters (temperature and the environment). In general, it was shown that the wear resistance and friction coefficient of MMCs are improved by increasing the volume fraction of the reinforcements. As the normal load and sliding speed increase, the wear rate of the composites increases and the friction coefficient of the composites decreases. The wear rate and friction coefficient decrease with increasing temperature up to a critical temperature, and thereafter both wear rate and friction coefficient increase with increasing temperature. The nano-composites showed best friction and wear performance when compared to micro-composites.

Tribological performance of self-lubricating aluminum matrix nanocomposites: Role of graphene nanoplatelets

“…The hardness of the material plays an important role to explain the wear behavior of materials. Generally, the softer materials have higher wear rates compared to the harder materials [6,20]. Further, in the literature, it is well known that there is an inverse relation between wear rate and hardness of the materials.…”

“…8). Increasing normal load causes to increase the amount of plastic deformation on the surface and hence increase the real area of contact at the surface during the wear test [6]. As stated in the Archard equation [21], the wear rate is directly proportional to the applied normal load.…”

“…The disadvantages of solid lubricant coatings are limited lifetime, difficulty in replenishment, oxidation and aging-related degradation, and poor adhesion. Therefore, to avoid the drawbacks of both the liquid and grease type lubricants and the solid lubricant coatings, a new method has been proposed by embedding carbonous materials in the metal matrices [6]. More specifically, the addition of carbon allotropes, such as Carbon Nano Tubes (CNTs) and graphene as reinforcement in metal matrices to improve the performance of materials has been a topic of interest over the last few years [7].…”

Identification and modelling of applicable wear conditions for stir cast Al-composite

“…Based on the Taguchi L 27 design layout, wear rates and COF values of the unreinforced alloy and composite were measured separately and compared among to each other. The variation (%) in the wear rate between the composite and base alloy, denoted by ∆WR, is expressed in the present study as [50]:…”

Tribological behavior of refined, bleached and deodorized palm kernel as an alternative lubricant

“…It is possible that, at 1 wt% concentration, ZDDP only plays a secondary role in the formation of tribo lm which causes high wear scar diameter. However, further increase in concentration reduces wear scar diameter since ZDDP is able to form a low-shear strength surface lm that can protect the surfaces from contact [22]. At high concentration, ZDDP additive can be adsorbed onto the metal surfaces e ectively and form a thin lm between the contact surfaces to protect the surfaces against wear [1].…”