In this study, the surface properties of Fe–1wt.%C based components produced by powder metallurgy (P/M) were enhanced using a NiCrBSi alloy deposited via the Powder Flame Spray (PFS) technique. Detailed examinations revealed that the inherent surface roughness of the P/M substrates promoted strong mechanical interlocking between the molten spray droplets and the substrate. X-ray diffraction (XRD) analyses confirmed the formation of Cr₂B (chromium boride) and various nickel–chromium silicide phases (Cr₃Ni₂Si and Cr₃Ni₅Si₂), which developed as a result of the rapid solidification occurring during the spraying process. Microhardness measurements indicated a significant increase in surface hardness from approximately 250 HV for the uncoated substrate to about 550 HV after coating, corresponding to an improvement of nearly 110%. This hardness level exceeds the conventional benchmark value of 40 HRC (≈400 HV), demonstrating that superior mechanical performance can be achieved through spray-induced energy transfer even in the absence of post-deposition heat treatment. Tribological evaluations showed that the coefficient of friction (COF), which ranged between 0.8 and 1.0 for the uncoated surface, was markedly reduced to approximately 0.2 with a coating thickness of 150 µm. Scanning electron microscopy (SEM) observations revealed severe material loss and deep abrasive grooves on the uncoated samples, whereas the NiCrBSi-coated surfaces maintained structural integrity owing to the presence of hard intermetallic phases, resulting in a more stable and improved wear regime. Overall, the results demonstrate that high wear resistance and low friction performance can be effectively achieved in powder metallurgy components through appropriate coating parameters, without the need for additional heat treatment.
Gözde Altuntaş (Wed,) studied this question.