Performance evaluation of self lubricating CuO added ZTA ceramic inserts in dry turning application. (August 2021) - Singh, Bipin Kumar
Abstract: Zirconia toughened alumina (ZTA) ceramic inserts infused with CuO solid lubricant were fabricated by Hot Press technique and studied. The creation of a Cu-rich phase of ionic copper at the grain boundaries slightly lowered the micro hardness of developed samples, while crack bridging and crack deflection phenomena fuelled by the ductile behaviour of Cu particles improved fracture toughness. Performance in terms of machining force, surface roughness and flank wear was measured while dry machining of AISI 4340 steel. The anti-friction properties of CuO added inserts resulted in less flank wear as compared to monolithic ZTA inserts while machining continuously up to 20 min, and the formation of a stable lubricating film at the tool-chip interface was proposed as the underlying mechanism. Further, a reduction in cutting force with increasing speed and improvement in surface roughness with increasing depth of cut was observed. Failure analysis of developed cutting inserts after 25 min of machining revealed brittle breakage (chipping, cracking and flaking), with cracks initiating inside the matrix without plastic deformation. Highlights: CuO added self lubricating ZTA cutting inserts were prepared by hot pressing technique. Morphology, flank wear, cutting forces and surface roughness of job were examined. CuO addition enhances the cutting performance and tool life of developed inserts. The mechanisms of fracture and flank wear were discussed.