Tool steel coatings based on niobium carbide and carbonitride compounds

► Evaluation of tool steel coatings based on NbC and Nb(C,N) compounds. ► Coatings produced by magnetron sputtering. ► Deposition pressure and mainly bias increase films' mechanical properties, due to microstructure densification. ► Under the optimized conditions: hardness of 37 GPa and elastic modulus of 400 GPa. ► Hardness and modulus vary linearly with N substitution for C.