Micro-Blasting as an Effective Pretreatment for Physical Vapor Deposition (PVD) Coating

Abstract

One of the primary requirements of physical vapor deposition (PVD) coatings for cutting tool applications remains strong adhesion between coating and substrate. Retention of the coating during machining becomes much more challenging, particularly for difficult-to-cut workpiece materials. The current work investigates different physical and mechanical characteristics of cathodic arc evaporated AlTiN coating with and without prior substrate treatment using micro-blasting with Al2O3 abrasives. Microstructural analysis indicates dimple-like structure due to prior substrate deformation by micro-blasting. Grazing incidence X-ray diffraction (GIXRD) patterns reveal peak broadening and shifting of peaks towards higher angle which indicate grain refinement and stress relief due to prior micro-blasting. 17-4 PH martensitic stainless steel is considered as workpiece material and cutting force and tool wear have been given emphasis. The result clearly highlights the supremacy of AlTiN coated tool with prior micro-blasting in terms of retention of coating, a reduction of up to 10% in cutting force and 20% in average flank wear after a machining duration of 5 minutes in comparison with the same coating without any treatment. Therefore, micro-blasting as a pre-treatment technique offers enough opportunity to augment properties particularly in terms of adhesion which can significantly improve the cutting performance of PVD coated tools