Cutting Performance and Wear Mechanism of Multilayer Diamond‐Coated Tools

Monolayer and multilayer diamond films are deposited on WC‐Co cemented carbide by hot‐filament chemical vapor deposition. The growth characteristics of diamond coatings are analyzed. Cutting performance characteristics such as tool life and the stability of machining process in the machining of presintered ZrO₂ are compared based on the variation of cutting speed and resultant cutting force, and workpiece surface roughness. For the monolayer diamond coatings, as the concentration of CH₄ increases from 1% to 5%, the diamond crystal is transformed from micron columnar crystal to nanocluster crystal. The multilayer diamond coatings combine the advantages of micron‐ and nanocrystalline structures. The multilayer diamond‐coated tool exhibits longer service life and better machining quality. Because of the appearance of the brittle–plastic conversion mechanism, the surface integrity of ZrO₂ processed by multilayer diamond‐coated tool is relatively high. As for the uncoated tool, the workpiece is mainly machined by brittle spalling. The interfacial stratified fracture system between the interlayers is proposed to be the toughening mechanism of the multilayer structure.