Mechanical and structural properties of multilayer c-BN coatings on cemented carbide cutting tools

Multilayer cubic boron nitride (c-BN) coatings represent a new deposition method that can improve adhesion on metal substrates. The multilayer c-BN system in this study consisted of a TiAlN interlayer (2–3.5μm), boron carbide (~1μm), and a c-BN (~2μm) gradient layer. This multilayer c-BN structure, exceeding 5μm in thickness, showed outstanding adhesion in atmospheric conditions even with high residual stress. Compared to monolayer c-BN coatings, the multilayer c-BN films had lower elastic moduli, and their critical loads were twice as high. The adhesion of the multilayer c-BN system was significantly improved because of the induced stress relaxation. •The multilayer c-BN system showed outstanding adhesion.•Lower elastic modulus was obtained with the multilayer c-BN films.•The multilayer c-BN coatings improved critical loads compared to the monolayer c-BN coating.•The multilayer c-BN coatings enabled greater top c-BN deposition thickness.