Danielle Bond

Effect of current and atomized grain size distribution on the solidification of Plasma Transferred Arc coatings

Plasma Transferred Arc (PTA) is the only thermal spray process that results in a metallurgical bond, being frequently described as a hardfacing process. The superior properties of coatings have been related to the fine microstructures obtained, which are finer than those processed under similar heat input with welding techniques using wire feedstock. This observation suggests that the atomized feedstock plays a role on the solidification of coatings. In this study a model for the role of the powders grains in the solidification of PTA coatings is put forward and discussed. An experiment was setup to discuss the model which involved the deposition of an atomized Co-based alloy with different grain size distributions and deposition currents. X ray diffraction showed that there were no phase changes due to the processing parameters. Microstructure analysis by Laser Confocal Microscopy, dilution with the substrate steel and Vickers microhardness were used the characterized coatings and enriched the discussion confirming the role of the powdered feedstock on the solidification of coatings.

Influência da corrente e granulometria do material de adição nos revestimentos processados por PTA

Welded coatings can be use to enhance the service life of components that operate under severe conditions. Plasma Transferred arc (PTA) is a hardfacing process, recognized for its homogeneous high quality deposits produced, and uses atomized feedstock. The bond of materials with different chemical compositions is always a challenge. This bond will depend on the optimization of the processing parameters, which influences the microstructure of the coatings and consequently its performance. This work analyzed the role of feedstock powder grain size, deposition current and mode on the hardness of a Co-based alloy (Stellite 6) coating using a experiment design tool. The results showed that the powder grain size of the feedstock has to be considered as a processing parameter together with the deposition current and mode as it influenced coating hardness.