<p>Diamond films were applied onto zirconia substrates, to potentially enhance the wear resistance of zirconia bearings under harsh working conditions, such as vacuum and/or no lubrication. To mitigate the mismatch between the zirconia substrates and the diamond films, a tungsten-molybdenum alloy transition layer was first deposited on the zirconia substrate using magnetron sputtering technology (MS), followed by the deposition of a diamond film through hot filament chemical vapor deposition (HFCVD). Orthogonal experimental methods were employed to explore the influence of transition layer composition, substrate temperature, methane concentration, and substrate roughness on the wear resistance. The results indicated that diamond films prepared on a tungsten-molybdenum alloy transition layer with W:Mo = 1:1 exhibited the highest quality. Furthermore, the substrate temperature, methane concentration, and substrate roughness significantly affected the quality of the diamond films. Specifically, the lowest friction coefficient and wear rate were observed when the substrate temperature was set at 850&#xa0;°C during HFCVD, methane concentration at 4.5%, and substrate roughness at 0.6&#xa0;μm, all leading to the best wear resistance, out of the analyzed samples. These findings provide a solid foundation for the potential application of diamond films in enhancing the wear resistance of zirconia bearings under harsh working conditions.</p>