A. Refke, M. Gindrat, K. von Niessen, Sulzer Metco AG, Switzerland, Wohlen, Switzerland; R. J. Damani, Sulzer Markets and Technology Ltd., Winterthur, Switzerland
The deposition of thin functional layers is gaining more and more importance to improve product performance for smart solutions including a broad variety of coating applications. Additionally the need for cost reduction of high volume or large area production implies economically improved processes with high deposition rates. Gas phase processes like PVD or CVD provide a wide range of solutions for coatings in the sub-micron to a few micron range. However, they suffer from low growth rates and high investment costs, whereas traditional thermal spray processes such as APS, VPS or HVOF lack from the capability to deposit comparable thin and dense homogenous layers and inhibit the problem of partially oxidation during the coating formation. Standard vacuum thermal spray processes like VPS and LPPS, operating typically in a pressure range of 100 mbar, are widely used and well established in industrial domains such as aeronautics, gas turbines and medical industries for fast deposition of dense oxide free layers in a controlled atmosphere. The new LPPS Thin Film (LPPS-TF) technology with its extended operational regime down to the 1 mbar range leads to unconventional plasma jet characteristics which can be used to obtain unique coatings with specific properties. This mainly covers applications for various thin layers of only a few microns which can be deposited with a high yield on large areas. Very dense ceramics as well as metallic or functional composite multi-layers with specific microstructure have been achieved. Due to the high enthalpy levels of the process the injected material can be partially or almost completely evaporated to produce a coating either from the liquid (splats) or vapor phase depending on the operating conditions. Even EB-PVD like thermal barrier coatings with defined columnar structure can be reproducibly deposited with an improved performance under economical production conditions. In addition the use of various diagnostics like in-flight particle detection (DPV), optical emission spectroscopy, enthalpy probes and IR-emission has supported the understanding and characterization of the different conditions of the plasma jet and its interaction with the injected material during the coating process to optimize the specific operation conditions. This paper presents the status of the LPPS-Thin Film technology as a hybrid coating process between thermal spray and vapor deposition and gives an overview of potential applications for functional thin coatings and large area coverage.
Summary: This paper presents the status of the LPPS-Thin Film technology as a hybrid coating process between thermal spray and vapor deposition and gives an overview of potential applications for functional thin coatings and large area coverage.
