Volume 9, Issue 2 (February 2012)
Evaluation of Plasma Transferred Arc Fe-Al Alloyed Coatings
Industrial equipment operates under aggressive service conditions aiming at higher efficiencies. In order to attend these demanding operating conditions materials have been developed among which are the FeAl alloys. This work studied Fe-Al coatings developed in situ by the deposition of mixtures of powders by plasma transferred arc on AISI304 plates. The aim was to characterize the effect on the features of coatings of (a) 15 and 30 %wt Al in the deposited mixtures and (b) 18 % Cr and 8 % Ni both individually and together. Characterization included dilution and hardness measurements, microstructure analysis, and exposure at 650°C for 2 h in an air furnace. Abrasive sliding wear tests were used to classify the processed coatings. Coating hardness varied between 400 and 500 Hv0.3 and a columnar solidification structure developed in all coatings but on those processed with the Fe 30 wt% Al powder blend, which presented a dendritic structure. This microstructure evolved to a columnar structure following exposure to temperature. The complex powder mixtures containing FeAlCrNi resulted in a coating with a more stable response when exposed to 650°C and superior wear behavior, whereas coatings developed from the deposition of FeAl blends showed poorer stability and the highest normalized wear.