Progress in duplex plasma processes in surface engineering
A duplex surface engineering process is one which combines two surface treatment or deposition methods; the most common example being a plasma diffusion process combined with a plasma-assisted PVD process. The paper discusses how such duplex processes can provide enhance tribological performance and describes recent developments in such processes, especially as applied to lightweight metals such as titanium and aluminium alloys. The paper begins by describing recent progress in understanding different types of tribological contacts and the way in which that improved understanding has enhanced our ability to identify suitable coatings and treatments to resist wear under each contact type, in particular by appreciating the need for the coating to be able to accommodate surface deformations, and the concurrent requirement for the substrate to provide adequate load support for the coating1-7 Progress in meeting the needs of the different types of contacts has been driven largely by the recent increased availability of advanced vacuum and liquid plasma-based coating and treatment processes which fulfil the surface needs identified by the contact theories. A mechanical properties approach to wear reduction is emphasized and new plasma-assisted PVD nanocomposite metal-metal and ceramic-metal coatings are described which possess near-ceramic hardness levels, but elastic moduli nearer to the (low) levels exhibited by the typical bulk materials used in engineering components. In effect, these coatings, through the high ratio between their hardness (H) and modulus (E), possess a long elastic strain to failure and can therefore better tolerate large substrate deformations (be they elastic or plastic) without yielding; they also exhibit high resilience and toughness (as quantified by an ability to absorb energy without fracture) The need to increase the H/E ratio is now attracting considerable interest, due to an improved understanding of materials and their behaviour and developments in coating process technology. With these new insights and processes, novel nanostructured films when combined with load-supporting duplex surface diffusion layers provide scope to ensure that coatings can survive under heavy loading conditions and provide exceptional wear resistance. The achievement of the load-supporting benefits using vacuum plasma processes was explained by the authors in early papers for steel substrates18241, and the concept has been developed for titanium alloys in recent papers25-33. Furthermore, the benefits of duplex processes for aluminium (and other) alloys have been achieved using liquid-based plasma using the plasma electrolytic oxidation (PEO) process34-37.
high velocity arc spraying FeNiCrAlBRE alloy coatings TIG remelting process microstructure
Allan Matthews Adrian Leyland
Department of Materials Science and Engineering, The University of Sheffield, Sir Robert Hadfield Bu Department of Materials Science and Engineering, The University of Sheffield, Sir Robert Hadfield Bu
国际会议
北京
英文
6-7
2012-10-23（万方平台首次上网日期，不代表论文的发表时间）