The aim of the current investigation was to study the high-temperature tribological performance of the high-velocity Oxyfuel sprayed 65% (NiCrSiFeBC)−35%(WC-Co) coating at the temperatures ranging from room temperatures to 800°C. The coating was produced on the hot forming die steels namely AISI H11 and AISI H13. The microstructural characteristics, surface roughness, microhardness, porosity and bond strength of the as-sprayed coatings were determined. Tribology study was done on the pin-on-disc tribometer at 0.5 m s −1 sliding velocity under the loads of 25N and 50N. The results have shown that the developed coating exhibited lower porosity, higher microhardness and performed much better than the uncoated specimens. The wear mechanisms of the coated specimens were mainly abrasive at room temperatures. Adhesive and oxidative wear were observed as the dominant mechanisms at the elevated temperatures.
Knowledge and optimization of tribological behavior of hot forming dies play an important role in attaining high process productivity. But research in this field has been limited. Keeping this in view, the current investigation aims to explore the potential of atmospheric plasma sprayed (APS) 65% (NiCrSiFeBC)–35% (WC–Co) coating in optimizing friction coefficients and minimizing the wear of AISI H11 and AISI H13 hot forming steels at elevated temperatures. Detailed characterization of the as-sprayed specimens was carried out using scanning electron microscopy/energy-dispersive spectroscopy and X-ray diffraction techniques. Wear and friction tests were done utilizing a high-temperature pin-on-disc tribometer under two different loads and temperatures ranging from room temperature to 800 ℃. The results have shown that the developed coating exhibited lower porosity, higher microhardness, and performed much better than the uncoated specimens. The wear mechanisms of the coated specimens were mainly abrasive at room temperatures and 400 ℃. Fatigue, tribo-oxidation, and three-body abrasion were observed as the dominant mechanisms at 800 ℃.
The High Velocity Oxy-fuel (HVOF) spray technique has been used by many researchers to deposit composite coatings, but there is less available literature discussing the fabrication of bulk metal matrix composites by this technique. In the current study, aluminum matrix composites with dispersions of alumina (Al2O3) and silicon carbide (SiC) particulates are fabricated by HVOF spray technique. The study comprises the steps of providing the substrate, preparing a mixed powder comprising a first metal powder as a matrix and a second metal powder comprising a ceramic and selected as reinforcement. The detailed procedures to prepare the bulk by using the same are reported. An in-depth characterization of the composite formed has been performed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Hardness of the composite formed is measured on Vickers microhardness tester. This study showed the possibility of fabricating bulk metal matrix composites of larger size by HVOF spray technique.
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