Production of wear-resistant antifriction coatings from MAX phases Cr2AlC and Ti2AlC on chromium alloy VKh1-17A and titanium alloy VT20

Abstract

The composition, mass transfer behavior, structure and properties of electrospark coatings produced on chromium alloy VKh1-17A and titanium alloy VT20 using Cr₂AlC and Ti₂AlC electrodes were studied. It was found that electrospark deposition (ESD) with a Cr₂AlC electrode forms MAX phases on both the chromium alloy and the titanium alloy. When a Ti₂AlC electrode is used, the MAX phase in the coating is observed on the chromium alloy. Vacuum annealing at 800 °C for 1 h increases the MAX-phase content in the coatings. The coatings on the chromium alloy are characterized by hardness H = 20.3 GPa and elastic modulus E = 288 GPa when a Cr₂AlC electrode is used, and by H = 24.8 GPa and E = 285 GPa when a Ti₂AlC electrode is used. The coatings on the titanium alloy have H = 17.6 GPa and E = 271 GPa when a Cr₂AlC electrode is used and H = 21.2 GPa and E = 267 GPa when a Ti₂AlC electrode is used. The coatings are fully (100%) continuous, up to 20 µm thick, and exhibit low coefficients of friction (K_fr < 0.25). The use of ESD and MAX-phase electrodes increases the hardness by more than a factor of 3.6, the wear resistance by more than a factor of 20, and the oxidation resistance by more than a factor of 1.4.