Abstract
Abstract Ni-Al intermetallic alloys are known for exhibiting superior high temperature properties. Processes such as thermal spray, combustion synthesis, physical vapor deposition and laser have been used to produce these coatings. However, the deposition of these alloys by means of plasma transferred arc (PTA) has not been widely studied. This study evaluated Ni-Al coatings processed in-situ by PTA. Coatings were processed with Ni and Al elemental powders (65%atNi-35%atAl) onto an AISI 1020 steel substrate. Different current intensities were used (70 to 120 A) to produce different dilution levels and thus different Fe contents in the coatings. The stand torch off was 10.0 mm. The plasma gas, shield gas and powder carrier gas flows were 2.0, 15.0 and 1.0 l.min-1, respectively. The powder feed rate was 5.8 g.min-1 and a travel speed of 100 mm. min-1 was used. The coatings were characterized by X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, optical microscopy and instrument indentation tests. The development of Ni aluminides was confirmed by X-ray diffraction for all current intensities. It was verified that the microstructure, hardness and the elastic modulus were influenced by current intensity and by the Fe content in the coatings.
Published Version
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