The Wear Resistance of NiCrSiB-20%CaF₂ Sinters in the Temperature Range 23-600 °C

In this work, powder metallurgy was used in order to produce self-lubricating composite materials. The NiCrSiB alloy as a matrix of the sinters and 20 wt. % CaF₂ as a solid lubricant were used. The sinters were subjected to wear tests using the pin-on-disc method at four different temperatures (room temperature (RT), 200, 400, and 600 °C). The coefficients of friction of the friction pairs were determined, and research on their wear mechanism was carried out. For this purpose, research techniques such as Light Microscopy (LM), Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), X-ray Diffraction (XRD), and profilometer were used. Based on the conducted tests, it was found that CaF₂ was smeared on the surfaces of the samples and counter-specimens, particularly at elevated temperatures. Moreover, it was found that micro-cutting and micro-ploughing are the major wear of the friction pairs at room temperature, while with the increasing temperature, they were dominated by the reduction of such mechanisms, which is associated with the formation of a tribofilm composed of CaF₂ and oxidation wear.