Research of tribological properties of surface MAO composites on D16T alloy

Abstract

Operation of mechanical engineering products operating under conditions of intensive wear at high rotation speeds and loads leads to their inevitable wear and significant metal losses. One of the methods for obtaining wear-resistant surfaces on products, for example, friction pair parts, is the microarc oxidation (MAO) method of aluminum alloys. The method allows obtaining dense hard surface wear-resistant composites based on α-Al₂O₃ (corundum) and γ-Al₂O₃. The structure, composition and surface quality of the resulting MAO coating significantly affect the performance characteristics of the product surface. The aim of the work is to determine the effect of porosity (10 and 16%) and surface roughness (R_a, equal to 2.7 and 0.51 μm) of MAO composites on D16T alloy on tribological properties and to evaluate the possibility of using MAO coatings in friction pairs, including end seals, under dry friction conditions. Comparative tests were carried out on an SMT-1 machine under dry friction conditions at a specific pressure in the friction pair of P = 0.5 MPa; the duration of the experiment was 90 – 91 min for each friction pair. The studies have shown that in many friction pairs, various types of damage (destruction) of the coating integrity, as well as deep abrasive wear, occurred. The porosity of the MAO coating in the range of 10 – 16% at different roughness values does not affect the abrasive wear of the coating. However, a porosity of 10% and a surface roughness of no more than R_a ≤ 0.51 ± 0.12 μm are preferable for achieving better tribological characteristics of surface MAO composites on D16T aluminum alloy.