New VPD machine for surface engineering research

Tecvac, which is part of the Wallwork Heat Treatment Group, has designed and built a unique surface engineering research machine for The University of Sheffield as part of a 500,000 EPSRC project. The new Tecvac IP70 machine combines two different Physical Vapour Deposition (PVD) coating technologies in a single production-scale vacuum chamber, and was specifically designed for the Research Centre in Surface Engineering, led by Professor Allan Matthews in the Department of Materials Science and Engineering. Funded by the Engineering and Physical Sciences Research Council (EPSRC), it will be used both for fundamental research and for near-market applications in surface engineering, covering a range of ceramics, nano-composite and glassy-metal plasma-based coatings, combined with a duplex substrate diffusion pre-treatment capability.

This will open up routes to new thin-film and nano-scale processes that can support innovative energy engineering and applications including the development of magnetic thin films. Projects using the new facility could lead to new types of ceramic engine components, related power train and fluid combustion controls, and other highly wear-resistant or lubricious applications throughout the energy engineering sector. The design of the new facility enables new coatings to be designed with fully controlled multiple and smoothly-graded properties to ensure compatibility with metals and ceramics and other advanced composite materials used in high-temperature, high-load, highly corrosive applications.

Long-term benefits

A major long-term potential benefit is that these multi-property, and multi-functional, long-life coatings support the development of component designs that can offer both extended maintenance intervals and significant gains in turbine and reciprocating engine performance. These facilities can also support oil exploration and production technologies, for example, by reducing wear and thus extending lives of the well heads, valves and drilling assemblies.

The highly modified IP70 equipment design, built to specifications developed by Prof Matthews and his colleague, Dr Adrian Leyland, enables research to be conducted on multiple layer surface coatings. The research team can combine the use of electron beams and magnetrons in a single process to create complex coatings with ceramic, metal and carbon-based constituents in an industrial-scale environment. This, in turn, enables coatings to be applied sequentially with a variety of elemental metals, ceramics such as titanium nitride and carbon-based coatings if required. Users can have a choice of process atmospheres with combinations of reactive or inert gases such as oxygen, nitrogen or argon depending on the research objectives.

The design includes, for example, twin magnetrons, twin electron beam assemblies, a mass spectrometer and allied process controls, operating systems, data logging and display facilities. This retains freedom for the research team to plan, modify and apply all critical parameters of the coating process, while ensuring safety and process integrity.

Supporting a materials property-based approach to tribology

Prof Matthews comments: "It opens up exciting areas of research for us. We can now support a number of advanced projects far more effectively and further develop our materials property-based approach to tribology, and design coatings for optimal ratios of elastic modulus and hardness. This will lead eventually to improvements in many engineering sectors, extending to aerospace, power generation equipment and medical devices. For example the IP70 also allows leading-edge work on material grain size and orientation at the nano level - a critical feature in the design of components for use in highly stressed environments within power generation turbines and drilling rigs."

The ability to combine different types of PVD coating processes in the research machine is also expected to lead to much lower application temperatures for ceramic and other high-performance coatings. In due course this is expected to lead to many new applications in medical, as well as aerospace and power generation products.

For more information about the Tecvac IP70 machine and other products and services, go to www.tecvac.com.