Application of composite electrolytic coatings to increase warning resistance of working bodies of grinding machines

Abstract

The article presents the results of research on the influence of composite electrolytic coatings (CEP) on the prospects of increasing the abrasive wear resistance of the working bodies of tillage machines: cultivator legs, disc harrows, plowshares.In this work, the influence of SiC (silicon carbide) filler particle sizes and their volume content in the nickel matrix on the tribological characteristics of QES applied to steel 45 samples was investigated.The formation of CEP with Ni-SiCano and Ni-SiC5, as well as with inclusions of amorphous boron was performed on a vertical cathode with continuous stirring of the suspension on our developed installation. The formation of CEP with SiC28, SiC50, SiC100 particles with the addition of amorphous boron powders was performed on a horizontal cathode. The change in the content of particles in the matrix was regulated by changing the ratio and (mixing time / sedimentation time) and changing the concentration of SiC and B particles in the electrolyte.CEP with inclusions of fractions 28/20 and 50/40 μm, which have the lowest wear at all loads, have the highest wear resistance among the given coatings. The filler content in such coatings is, respectively, 24 and 28 vol.%. At the same time coatings with inclusions of fraction of 28/20 microns have a little less wear. The weight wear of such samples is an order of magnitude less than for coatings with smaller and larger particles. Compared to galvanic nickel, such coatings have a reduction of wear of 12, 9 and 5 times at loads of 20, 40, 60 N, respectively.Analysis of the test results showed that the coefficient of friction is significantly affected by the friction load and the particle size of the filler SiC and there is a clear pattern that with increasing load such as the coefficient of friction decreases. Regarding the influence of the particle size of KEP filler on the coefficient of friction f, it can be noted that the coefficient of friction decreases with increasing particle size and for the range of particle sizes of filler 40… 60 μm the coefficient of friction is minimal. For coatings with large filler particles (fraction 100/80) the coefficient of friction is higher.The highest wear resistance of coatings with inclusions of size 28… 50 μm may be due to the distribution of the load they receive. The load on the solid inclusions is equal to the actual contact pressure when their size is smaller or commensurate with the size of a single contact spot (2-10 μm). For compositions with optimal particle sizes (28 μm) there are no processes of setting, abrasive and brittle fracture and there is a normal mechanical-oxidative wear process.Thus, tribological studies show the prospects and effectiveness of CEP to increase the wear resistance of the working bodies of tillage machines.