Abstract

During the design and development of new layer coating systems, layer characteristics can be directly influenced or modified. In this case, the modification of the powder is of primary significance, i.e. factors such as grain size, grain size distribution and composition. In this paper, fine-crystalline Al2O3+SiC layer systems of differing compositions are presented. Due to their especially fine crystalline structure, as well as the imbedding of fine SiC particles in the Al2O3 matrix, these layers demonstrate improved properties compared with standard Al2O3 coatings. Additionally, improved fracture behaviour of these coatings is apparent - their behaviour can be described as "quasi-ductile". The coating process utilised was the HVOF (High Velocity Oxy-Fuel Flame Spraying) process. As the spraying system, a Top-Gun ultrasonic (airless) spraying (system) equipment was used. The coating parameters were optimised in conjunction with the ATZ Evus Company. Microscopic analyses were carried out using the SEM and EDX methods. The structural analysis of the coating was determined using X-ray diffractometer measurements. In order to determine characteristic material properties, a range of investigation methods were applied. These latter included the Palmquist tests, by which fracture toughness was quantified. Additionally, tribological investigations were performed using an abrasive disk method. In the results, the influence of the SiC content on mechanical properties was investigated. Furthermore, a comparison with standard Al2O3 coatings was made. Paper text in German.

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