Research of tribotechnical characteristics of restored and hardened gear pumps of type NSH-U

Materials, equipment and research methods, as well as the results of tribotechnical tests on a friction machine are presented. Comparative studies on the wear of coatings formed by micro-arc oxidation (MAO) on plastically deformed aluminum alloys AO3-7 and AK7ch at various modes and electrolyte composition have showed that an increase in the content of potassium hydroxide and liquid sodium glass in the electrolyte is, respectively, above 3 and 14 g / l leads to a decrease in the wear resistance of the hardened layer. On the other hand, when their content in the electrolyte is below the specified values, the coatings have a higher microhardness, which leads to significant wear of counter samples. The formation of a hardened layer at a current density of 25 A / dm2 ensures minimal wear of the joint. The rational modes of MAO and the composition of the electrolyte have been established, at which the least wear of the tested compounds is achieved: current density - Dt = 25 A / dm2; microarc oxidation time - T = 2 h; electrolyte temperature - t = 20ºС; the content of potassium hydroxide in the electrolyte - СKON = 3 g / l; the content of liquid sodium glass in the electrolyte - СNa2SiO3 = 14 g / l.