Friction Coefficient of Single-Crystal Aluminum Oxide under Low Sliding Velocity Conditions with Metal and Polymer Materials

The article presents the results of an experimental determination of the friction coefficient of various materials (95Kh18 steel and BrAZh9-4 bronze, F-4 fluoroplastic, PA-6 polyamide, and MPG-7 graphite) in a friction pair with single-crystalline aluminum oxide under low speeds and various loading conditions. Determining the friction coefficient of aluminum oxide at low sliding velocity allows recording and evaluating the static friction for various counterbody materials, identifying the mechanisms of interaction between rubbing bodies and their influence on friction processes. Studies of the tribological characteristics of single-crystal aluminum oxide show that it has no antifriction properties, and, when using it in a friction unit, we need to take into account the pairing material, the load on the friction contact, and the sliding velocity. Aluminum oxide has a high affinity for metals, which causes strong adhesive interaction up to wear with cohesive destruction of metals. Polymer materials such as fluoroplastic and polyamide weakly adhesively interact with aluminum oxide, which ensures stable sliding within lubrication with low friction coefficients over a wide range of loads and velocity. Dry friction of the self-lubricating graphite material is determined by the tribological properties of the graphite. At low loads and sliding velocity, the adsorption component of friction is revealed. When forces are sufficient to destroy bonds in crystalline layers of graphite, the friction process is limited by the effect of self-lubricating of graphite.