Influence of load, sliding speed, and temperature on the tribological behavior of plasma sprayed BaF2-doped YSZ composite coatings

Abstract

This report explores the tribological characteristics of BaF₂-doped YSZ coatings under varying loads, speeds, and temperatures. Up to 10 N load, the friction coefficient (COF) decreases owing to elastic contact, then it stabilizes within 0.78 – 0.80 as plastic contact dominates. At 650 °C, BaF₂ extrusion under high loads reduces the COF to 0.56. Increased speed further lowers the COF through debris ejection and asperity softening. The wear rate rises with load and speed owing to Hertzian stress and tangential impact, respectively. Fatigue and abrasive wear are the main wear mechanisms. BaF₂ layer provides significant wear protection, and with temperature, its shear strength reduces, lowering the COF to 0.39 and wear rate to 5.36 × 10⁻⁴ mm³/Nm at 750 °C.