Investigated On Preparation Process Of Chromium & Titanium Nitride Films Based On Pem Controlled Reactive Magnetron Sputtering

In this paper, a PEM (Plasma Emission Monitor) controlled CFUMSIP (Closed Field Unbalanced Magnetron Sputtering Ion Plating) system is used to deposit titanium nitride & chromium nitride films under different substrate bias (Us) and relative monochromatic intensity (P%) at the characteristic wavelength of metallic target elements (Ti or Cr) which is emitted by the near-target plasma. The chemical & phase composition, morphology, fine structure, mechanical properties and tribological performance of the obtained films are evaluated by using EDS, XRD, SEM, TEM, Vickers micro-hardness tester, Rockwell indentation and Pin-On-Disc tester, respectively. Based on the results, the effects of P% and Us on the composition, microstructure, and properties of the prepared titanium nitride & chromium nitride films are experimentally investigated. Finally, the optimized parameters of P% and Us for the deposition of titanium nitride & chromium nitride films by the PEM controlled reactive magnetron sputtering method are proposed.The results of this research show that when the PEM controlled reactive magnetron sputtering method is utilized to prepare metallic nitride films, the N/Me ratio of obtained films is primarily controlled by P%, and is also slightly affected by Us. Along with the decrease in P% from 80 to 40, the N/Me ratios of either titanium nitride films or chromium nitride films increase apparently. However, the N/Ti ratio of the former films varies in a range of 1.27～1.58 which implies the excess of nitrogen element, while the N/Cr ratio of the latter films gradiently increase from 0 to 1.06.Under different combination of P% and Us, all the obtained titanium nitride films have the same Ti-absentδ-TiN phase composition. However, their growth orientation and grain size are influenced by P% and Us significantly. As P% decreases, the preferred orientation ofδ-TiN phase changes from (200) to (220), while finer grain ofδ-TiN phase is obtained. To increase Us could cause the preferred orientation varies again from (220) to (111), while the grain size also show further decreasing trend. Unlike what happens in the titanium nitride films, the decrease in P% makes the dominating phase in the obtained chromium nitride films vary from pure chromium toβ-Cr2N, and then CrN. However, the increase of Us mainly causes the improvement of the crystallization of theβ-Cr2N phase.The results also reveal that the microhardness and adhesion of obtained metallic nitride films are influenced by P% and Us significantly. The wear performances of the films are then affected by P% and Us through the hardness and adhesion of the films by very complicated mechanisms. As P% is decreased, the microhardness of titanium nitride films decreases slightly then increases gradually, and finally achieves the highest level of HV0.02=1914 at P%=40. As for the chromium nitride films, their microhardness show a monotone increasing trend along with the decrease of P%, and also achieve the highest level of HV0.02=1752 at P%=40. However, due to the possible mechanisms such as nitrogen oversaturation, rising of internal stress, increase of the content of the hard & brittle phase, along with the increase of film hardness at lower P%, the films reveal worsen adhesion and then jeopardize their wear performance. As the result, both of the titanium nitride films and the chromium nitride films achieve their lowest volume specific wear rate. Although the microhardness of the titanium nitride and chromium nitride films could be improved by using higher Us, their adhesion and wear resistance are worsen for the similar reasons. Therefore, the titanium nitride films and chromium nitride films achieve their lowest volume specific wear rate at Us=-60 V and Us=-70 V, respectively. The above results demonstrate that in order to get best wear performance, it is essential to appropriately balance the hardness and the adhesion of the films. Finally, we suggest when the PEM controlled reactive magnetron sputtering method is used to prepare the titanium & chromium nitride films, P% should be set to 60, and Us should be set to-60 V and-70 V for the titanium nitride films and the chromium nitride films, respectively.