Fundamentals of High Power Impulse Magnetron Sputtering (HIPIMS) - Plasma Studies and Materials Synthesis

To be effective, many modern technologies need component parts with very special surface properties. The parts of an F1 engine must be very resistant to wear, medical implants must not corrode inside the human body, and even everyday objects like the surface finish of glasses-frames and mobile phones must be able to survive the knocks and scratches of day-to-day life. Industry very often gets these desirable properties by taking an everyday material such steel and protecting it with a highly specialised surface coating . Our research aims to improve our understanding of an exciting new technology for producing coatings.The new method is called HIPIMS (which stands for High Power Impulse Magnetron Sputtering) and is a very recent addition to a family of plasma techniques, in which the coating is produced by bombarding the surface you want to coat with carefully prepared atoms and ions. HIPIMS was first discovered in 1995, and recent work in our group and elsewhere has already shown that it produces an excellent plasma, with a combination of ion properties which should produce hard wearing, corrosion resistant coatings. We have also made some early trials of the coatings themselves, and they do indeed turn out to be very promising.Because it is so new, there are a number of key features of HIPIMS we don't yet understand. HIPIMS works by making a series of short, very high-power pulses. We know that the plasma achieves unusual conditions during the pulse, but the details are not yet worked out. Similarly, the way the plasma changes during the pulse is not yet clear. Answering these questions would be of interest to scientists who study plasmas, and would help technologists to learn how to apply HIPIMS to create new, better coatings.In the research we will measure properties of HIPIMS plasmas to understand how the composition of the plasma changes with time. We will do this by carefully analysing the electrical properties of the plasma and studying the spectrum of the light it emits. We will feed the data into models of how HIPIMS operates and work to develop a theory which explains the pulse behaviour. We will also make coatings using HIPIMS and measure their properties (for example how hard they are) and examine them under electron microscopes to help our understanding of how the properties relate to the microscopic structure produced by the HIPIMS plasma. This understanding should help industrialists to develop HIPIMS processes which can generate new, better coatings. In a few years our car engines, hip-replacements and mobile phones may all be reliant on components developed using HIPIMS!