Development of a high flow rate aerodynamic lens system for inclusion of nanoparticles into growing PVD films to form nanocomposite thin films

摘要

Hard coatings for wear protection of tools, bearings, and sliding parts play an important role in industrial manufacturing. Nanocomposite coatings are being used in this context to improve the mechanical properties. The technology applied therefore is often based on physical vapor deposition (PVD), in which the different materials are co-deposited. In these processes it is not possible to control the properties of the disperse phase and continuous phase independently. Here, we present a technology which combines aerosol technology with thin film technology to produce nanocomposite coatings directly, which gives us full control over both phases. It is based on an upscaled three-stage aerodynamic lens, which allows to bring nanoparticles from an atmospheric-pressure aerosol reactor into a PVD vacuum chamber operating at low pressure (2 Pa). This requires the use of a higher mass flow rate than conventionally used in aerodynamic lenses, so that a rational upscaling strategy for designing an aerodynamic lens for larger mass flow rates is proposed. Here, an array consisting of eight parallel three-stage aerodynamic lenses having each a mass flow rate of 0.6 slm using argon and 0.71 slm using nitrogen is built and optimized, assisted by CFD and numerical trajectory analysis. The transfer efficiency has been investigated numerically and experimentally. It is possible to transfer 80% of the particles with only 1.3% of the gas into the deposition chamber. A number of coatings consisting of titanium carbonitride nanoparticles embedded in a PVD chromium oxynitride film with varying nanoparticle content were produced. Electron microscopy shows the successful incorporation of the nanoparticles in the thin film. A reduction in film crystallite size with increasing nanoparticle content was found. A reverse Hall-Petch behavior was observed.