Influence of pulsed-substrate bias duty cycle on the microstructure and defects of cathodic arc-deposited Ti1-xAlxN coatings

• Published in: Surface & coatings technology 2021-08, Vol.419, p.127295, Article 127295
• Main Authors: Salamania, J., Johnson, L.J.S., Schramm, I.C., Calamba, K.M., Boyd, R., Bakhit, B., Rogström, L., Odén, M.
• Format: Article
• Language: English
• Subjects: Arc deposition; Bias; Cathodic arc; Cathodic coating (process); Cemented carbides; Coatings; Columns (structural); Compressive properties; Crystal defects; Duty cycle; Microstructure; Preferred orientation; Pulsed-substrate bias; Substrates; Ti-Al-N
• ISSN: 0257-8972; 1879-3347; 1879-3347
• DOI: 10.1016/j.surfcoat.2021.127295

The influence of pulsed substrate bias duty cycle on the growth, microstructure, and defects of Ti1-xAlxN coatings grown by cathodic arc deposition was investigated. Ti1-xAlxN coatings of varying compositions (x = 0.56, 0.38, 0.23) were deposited on cemented carbide substrates with 10, 25, 50, and 95% duty cycles of −50 V pulsed-bias under 10 Pa of pure N2 gas. Coatings grown at low duty cycles (10 and 25%) showed strongly textured, under-dense coatings with facetted columns and low amount of lattice defects. Applying higher duty cycles (50 and 95%) produced coatings that have denser microstructures, less preferred orientation, increasing compressive stresses and increased lattice defect densities. Our study elucidates how duty cycle variation not only changes the overall average energy supplied at the growth front but also kinetically influences the coating growth and thus microstructure and defect structure. •Ti1-xAlxN coatings were grown on WC-Co substrates with 10, 25, 50, and 95% duty cycles of -50 V pulsed-substrate bias.•Duty cycle variation significantly and systematically affected their growth, microstructure, and crystallographic defects.•Low duty cycle conditions produced textured, under-dense coatings with facetted columns and low amount of lattice defects.•Higher duty cycles produced coatings that have denser microstructures, less texture, compressive stresses and increased lattice defects.•Duty cycle change was a powerful tool to achieve arc coatings with low defect density, high crystal quality and low stress.