Studies of tribological characteristics of nickel-based composite coatings formed using detonation gas thermal spray

The article presents a research into the formation of wear-resistant coatings on critical parts of the mining equipment. The objective is to study the tribological properties of the nickel-based coatings obtained by high-speed detonation gas-thermal spraying in dry sliding conditions under the “ball-disk” scheme. Understanding the wear dynamics of these coatings during operation is important for determining the most efficient material for particular operating conditions. The main task is to perform a comparative analysis of the wear resistance of different types of sprayed coatings such as NiCrBSi, NiCrBSi/B4C, NiCrBSi/B4CNi and NiCr/WC. Pure NiCrBSi powder and mixtures of NiCrBSi/B4C (90/10); NiCrBSi/B4CNi (85/15); and NiCr/WC (85/15) powders were used as the initial material for surface coating. The following powders were used for coating: the NiCrBSi powders of the PR-NKh17SR4 grade produced by POLEMA JSC, the NiCr/WC powders of the the VSNGN-85 grade produced by TC Technikord LLC, the B4C powder of the F1200 grade produced by Promkhim LLC and the B4CNi powder of the PKBN-30 grade produced by NPO Spetsborzaschita LLC. Composite coatings with a common characteristic of the nickel matrix were obtained using the highspeed detonation gas-thermal spraying method. Following the wear tests in dry sliding conditions under the “ball-disk” scheme, the surfaces of the composite coatings were examined using the scanning electron microscopy. It was found that the NiCrBSi, NiCrBSi/B4CNi and NiCrBSi/B4C coatings demonstrate the friction coefficients during the stable wear period at 0.026, 0.024 and 0.028, respectively, while their wear rates reach 4.73×10-11, 1.20×10-11 and 1.18×10-11, respectively. Addition of B4C improves the wear resistance of the NiCrBSi coatings. The NiCr/WC coating offers the best wear resistance among all the coatings considered, but it is characterized with a high friction coefficient of 0.055. A conclusion is made that the wear resistance of the composite coatings with the ceramic filler is superior to the wear resistance of the NiCrBSi alloy.