Characterization of NiCrAlC PTA coatings

Abstract

Surface tailoring with plasma transferred arc (PTA) hardfacing involves the deposition of powder mixtures to produce coatings with an almost unlimited chemical composition. PTA hardfacing is particularly important for processing low weldability alloys, such as those for high-temperature applications, of which NiCrAlC is an example. This study analyzed NiCrAlC coatings processed by PTA using a mixture of elemental powders. Deposition on AISI316L plates was carried out with currents of 100 A and 130 A to induce variations in the chemical composition of the coatings, which were also subjected to isothermal exposure at temperatures of up to 1000 °C for up to 72 hours in an air furnace. The results show that the aluminide compounds were stable, the coatings that solidified more slowly having the highest hardness after temperature exposure and potentially being suitable for use in high-temperature abrasion environments.

Abrasion Resistance of Nickel Aluminide Coatings Deposited by Hvof and Pta Processes

“…The measured dilution level in this case is 23%, meaning that the elements of substrate were incorporated into coating. This dilution level is smaller than that observed for the same coating composition processed using elemental powders [9], and some reasons for this discrepancy were discussed in [12]. The transverse cross sections of the PTA coatings were prepared using standard metallographic procedures.…”

“…This family is composed by an intermetallic matrix with dispersed carbides. Following this trend, nickel aluminides were employed as raw material for HVOF-sprayed [8] and PTA-welded coatings [9]. The abrasive wear resistance of HVOF-sprayed coatings can be improved after heat treatments [10].…”