Abstract
The main application of HVOF processes is the production of wear and/or corrosion protective coatings based on cermets (e.g. WC-Co). To reduce the weight of the sprayed volume, to increase the oxidation resistance and to reduce the costs of consumables SiC based cermets are of particular interest. The outstanding mechanical, thermal and chemical properties of SiC have made this material attractive for thermal spray applications. Thermal spraying of pure SiC is impossible, because of its decomposition at elevated temperatures. The development of suitable alloys as metallic binders enables the wetting of the SiC particles with reduced reactivity between the matrix and the hard particle during the thermal spray process. In the present work starting from the metallurgical concept of the metallic matrix to the production route from the atomization of the metallic matrices, the spray drying and sintering as well as the processability of the composites is discussed. The coatings are characterized concerning porosity and SiC content using optical and scanning electron microscopy, digital image analysis, X-ray diffraction and micro hardness testing. The wear resistance of the coatings is determined by oscillating wear test. Microstructure and performance of the SiC composite coatings are discussed with respect to technical applications.
