Abstract:In the present study, the effects of process parameters (output voltage x, nitrogen flux l and specific strengthening time s) on the microstructure and wear resistance properties of TiN coatings prepared by electrospark deposition (ESD) were investigated systematically. The microstructure of the coatings was characterized for thickness (TOC), content of TiN (CON) and porosity (POC). A statistical model was developed to identify the significant factors affecting the microstructure and wear resistance of the coatings. The results show that the output voltage x and nitrogen flux l present significant effects on majority of the evaluation indexes such as TOC, friction coefficient (COF) and wear mass loss (Id), while the specific strengthening time s has a significant effect on POC and a small effect on the other indexes. The optimal process parameters were obtained as follows: output voltage (x, 60 V), nitrogen flux (l, 15 L/min) and specific strengthening time (s, 3 min/cm2). The variation of wear mass loss (Id) by the variation of the output voltage (x) and nitrogen flux (l) is attributed to the change of wear mechanisms of TiN coatings. The main wear mechanism of TiN coating prepared under optimal process parameters is micro-cutting wear accompanied by micro-fracture wear.

Key words: electrospark deposition (ESD); TiN; coating; wear resistance; statistical model; process parameters