Evaluation of Heat Treatments and Their Effects on the Corrosion Behavior of TiAlON Coatings Prepared by Cathodic Arc Evaporation on D3 Tool Steel

A series of tialon coatings were synthesized in a gaseous mixture of argon, nitrogen and oxygen by cathodicarc evaporation method using a ti–al mosaic target. oxidation of coatings was carried out by heating the coatedsamples at the temperatures of 500, 600, 700, and 800°c for 1 h in air atmosphere. it was found that heat treatmentchanged the microstructure and composition of the coating. the dark copper color of tialon films was alsochanged due to the heat treatment. the peak intensities of tin were decreased and that of fe was increased with anincrease in heat treatment temperature. furthermore, the amorphous al2o3 in grain boundaries was transformed toa crystalline structure with increasing temperature. the variation in the chemical composition of the coatings wasrecognized to be a function of heat treatment temperature. the oxidizing treatment promoted not only the growthof titanium and aluminum oxides on the pore wall of the coating, thereby allowing a partial pore sealing, but alsothe inter diffusion processes which increased the coating internal cohesion. the structure of tialon coatings wasstudied using x-ray diffraction (xrd) and scanning electron microscopy (sem). morphological characteristicswere analyzed by means of an atomic force microscopy (afm). corrosion resistance tests carried out in the3.5%wt nacl solution showed reduced corrosion current density due to the oxidation treatment. this post-coatingtreatment could be effective in improving the corrosion protection of tialon coating on a d3 substrate.