A high-velocity oxy-fuel (HVOF) plant was converted to process aluminum oxide. Three HVOF burner nozzles with different geometries were examined. To optimize the transfer efficiency, numerical simulations of the spraying process were carried out. The transfer efficiency, the layer structure, and the hardness were investigated experimentally. The modified nozzles promised an improvement in the degree of melting of the particles. However, some of the melted particles caked on the inside of the nozzle and melted together into large particles. Some of these particles dislodged and were thrown out of the nozzle. This led to a reduction in transfer efficiency. In this paper, a novel hybrid HVOF system, combined with a conventional flame spray burner, is developed to solve the problem of caking. Thus, a maximum transfer efficiency of 52% could be achieved. The layers were relatively dense and their hardness was between 850 and 1000 HV. Paper includes a German-language abstract.

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