Of Ce Modified The Role Of Ti-al-n Coatings

Binding strength between coating and substrate and oxidation resistance is the most important elments which decide the working time and using efficience of coating knife and hot die tools. In this thesis , Effection of rare earth element Ce on Ti-Al-N series coating modification, especially the Critical load and high temperature oxidation resistance is studied.Ti-N coating added rare earth element Cerium and aluminium are deposited on polished substrates of 4Cr5MoV die steel and W18Cr4V high speed steel by means of arc ion plating; The hardness and critical load of the coatings are obtained through the hardness microscope equipment produced by Japan and WS -92 scrape instrument; The microstructures and phase constitution of the coatings are also studied by means of Scanning electron microscope (SEM) and X-ray diffraction (XRD) technique.; High temperature oxidation resistance experiments are completed by DRZ-8 current resistance furnance , SDT2960 hot weight analysis equipment and Q10 hot Difference scan instrument are applied to hot analysis. The results are as follows:With the addition of Cerium, wear resistance and surface porosity of Ti- Al -N series coating are improved obviously, meantime, critical loadis increased by 5~10N. In this experiment conditions, the beginning oxidation temperature of Ti(Al,Ce)N concluding 25 percent Al is increased from 614C of TiN to 895C, high temperature oxidation resistance of Ti (Al,Ce )N is the best of all, which indicate great potential effect of Cerium in hot resistence coating. Cerium was so active that it can react with miscellaneous materials to form compound, which can improve the state of Crystal boundary and increase the Binding strength between coating and substrate. The are two main reasons that Cerium increase the high temperature oxidation resistance of films: one reason is that Cerium can first react with oxygen to form oxide in the surface of the coatings,which can impede oxygen to Permeate into the film surface. The other is that Cerium can mix with A12O3 , which increase the binding strength of oxidation coatings and reduce the growth dint. As a result, both the Removal resistance and high temperature oxidation resistence are increased.