A study and comparison of two commercially available and competitive physical vapour deposition techniques has been made. Titanium nitride (the most widely used hard and decorative coating) has been deposited by both steered arc and the new Arc Bond Sputter (ABS) magnetron technique under a range of deposition conditions. The coatings have subsequently been analysed by a variety of methods and the results reported here. The steered arc technique has been identified as the better technique for everyday ease of use in producing mononitride and monocarbide coatings with good batch uniformity and reproducibility in terms of composition and microstructure. However, for versatility the ABS magnetron technique allows the possibility to vary multiple parameters and hence change coating properties at will, albeit with some difficulty to maintain stable and reproducible operation. In this respect, plasma uniformity is discussed and problems with water vapour contamination and gas flow regulation are highlighted and possible solutions suggested. The coating-substrate interface region is considered, and the merits of metallic interlayers and arc etching are compared. An interlayer achieves good adhesion only at an optimum thickness as confirmed in this work. The good adhesion afforded by the arc etch phase of both processes is addressed and the ion-surface interactions modelled using commercially available computer software. The improvement in adhesion on high speed steel is explained by sputtering of the substrate matrix leaving hard carbide particles standing proud of the surface. When deposition takes place, the carbides mechanically key the coating to the substrate surface, and also possibly act as physical blocks to interfacial crack propagation. A theoretical contribution to the explanation of preferred crystallographic orientation during coating deposition is proposed derived from experimental results, surface physics and semiconductor growth theory. This attempts to explain the flexibility of sputtering techniques to produce a wide range of orientations, and the reasons why arc evaporation almost always produces {111} orientated coatings. Finally, a consideration of a comparatively new analytical technique (Glow Discharge Optical Emission Spectroscopy) to the application of PVD coatings evaluation is addressed. The speed and versatility of this technique makes it strategically important in the future research, development and quality control of thin film production.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:387143 |
| Date | January 1994 |
| Creators | Ives, Malcolm |
| Publisher | Sheffield Hallam University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://shura.shu.ac.uk/19861/ |
Page generated in 0.0019 seconds