This article reports on the formation of strongly overstoichiometric ZrN x>1 and Ti(Al, V)N x>1 coatings by reactive magnetron sputtering. Problems in the formation of overstoichiometric coatings and possible ways to form strongly overstoichiometric TMN x>1 nitride coatings up to TMN x=2 dinitride coatings are discussed; here, TM are transition metals such as Ti, Zr, Mo, Ta, Nb, W, etc. The coating stoichiometry x = N/TM strongly influences its electrical and mechanical properties. The creation and properties of reactively sputtered ZrN x coatings were investigated. It was found that (1) the electrical resistivity of the ZrN x coating varies with increasing x from well electrically conducting films with x ≤ 1 through semi-conducting films with x ranging from 1 to ≤ 1.26 to non-conductive with x ≥ 1.3, showing that the stoichiometry x is a strong parameter which enables to control an electric conductivity of the coating in a wide range, (2) electrically conductive coatings with x ≤ 1 are harder than the semiconducting and electrically insulating coatings, and (3) the ZrN 2 dinitride film cannot be created due to the formation of a Zr 3 N 4 phase whose formation enthalpy is greater than that of a ZrN 2 phase. Further, it is shown that the main problem in the formation of strongly overstoichiometric TMN x>1 and dinitride TMN 2 coatings is a strong increase of ionization of the nitrogen sputtering gas to achieve a necessary high ratio N/TM > 1. Trends enabling the mastery of formation of the TMN 2 dinitride coatings are briefly outlined.
ASJC Scopus subject areas
- Physics and Astronomy(all)