Scientists from the International Advanced Research Centre for Powder Metallurgy and New Materials (ARCI), Hyderabad, an autonomous R&D Centre of the Department of Science and Technology (DST), have developed advanced nanocomposite protective coatings to improve the durability of cutting tools used for machining critical superalloys. The research specifically addresses the manufacturing challenges posed by nickel-based superalloys such as Inconel 718 (IN718), IN625 and IN617, which are indispensable for components operating under extreme conditions in aerospace, energy and petrochemical sectors.
The team developed two coatings—Titanium Aluminium Silicon Nitride (TiAlSiN) and Chromium Aluminium Silicon Nitride (CrAlSiN)—deposited using cathodic-arc physical vapour deposition on tungsten carbide cutting tools. Performance testing revealed that coating effectiveness depends significantly on the specific superalloy chemistry. For IN718, TiAlSiN-coated tools showed an 80% improvement in tool life compared to uncoated tools, while for IN625, the improvement was approximately 60%. For IN617, CrAlSiN coating demonstrated remarkable superiority with over 200% increase in tool life.
Failure analysis identified that the major cause of tool damage was repeated adhesion of workpiece material to the tool surface, leading to chipping when the adhered material breaks away. The coatings helped delay this damage mechanism, with abrasion, adhesion and attrition contributing to the overall wear process. Metal chips generated during machining exhibited characteristic shear bands and serrated patterns, reflecting intense thermo-mechanical conditions during cutting.
The research provides a scientific basis for selecting coatings according to the specific alloy being machined, moving away from seeking a universal coating solution. This application-specific approach can reduce downtime, improve productivity and lower manufacturing costs for high-value engineering components. The study was conducted at ARCI's Centre for Engineered Coatings and has been published in the journal Materials Today Communications.