NiCrSiBC Coating: Microstructure and Hardness of Coatings Processed by Arc and Laser

The processing technique rules the characteristics of coatings. The heat input that depends on the technique and deposition parameters, accounts for changes on the dilution and solidification rate. Depositing alloys with low metallurgical complexity with a faster solidification rate can result on microstructure refining and therefore a higher mechanical resistance is expected. However, in the deposition of more complex alloys, a higher cooling rate can suppress the formation/precipitation of hard phases/compounds compromising the mechanical resistance of coatings. In this study, the influence of the processing technique on microstructure and hardness of Colmonoy-6® alloy coating was analyzed. Coatings were processed by plasma transferred arc (PTA) and high power diode laser (HPDL) on plates of AISI 304 with two different dilutions each. High quality and defect-free coating were processed. Iron content in coatings and their cooling rate were determined by the deposition technique. Consequently, significant changes in microstructure and hardness of coating occurred and were associated with the phase distribution, morphology and size of compounds, mainly of borides.

Hardfacing; Processing; Plasma Transferred Arc; Laser cladding