Influence of the handling parameters on the characteristics of HVOF sprayed coatings processed by means of fine WC-12Co (2 - 10 μm) powders

摘要

In order to apply near net shape coatings on parts with complex geometry, it is crucial to be aware of the various interrelationships between the handling parameters of the spray process and the coating properties. In this study, the influence of different handling parameters (such as the spray angle, the spray distance, the track pitch, and the gun velocity) on the deposition rate and the coating properties (microhardness, roughness and porosity) during HVOF spraying of fine agglomerated and sintered WC-12Co powder (2 - 10 μm) with WC particles in the submicron range (400 nm) was investigated. Prior to these examinations, the spray spot profile of the powder laden HVOF flame, with respect to its shape and position relative to the flame axis, was characterized. In addition, the temperature development of the substrate depending on the backside air pressure was recorded during the coating experiments by means of thermocouples. It was found, that alterations of the handling parameters have significant effects on the deposition rate and the coating properties, which are discussed within this study.