Department of Technology of Functional and Structural Materials, Vladimir State University named after Aleksander G. Stoletov and Nikolay G. Stoletov, Vladimir, Russia:

E. S. Prusov, Assistant Professor, e-mail: eprusov@mail.ru
V. A. Kechin, Professor, Head of a Department
A. V. Kireev, Research Engineer

Metal matrix composites, based on high-aluminum zinc alloys, are the promising tribological materials representing an effective alternative to bearing bronzes, antifriction aluminum alloys and tin babbitts. This paper shows the research of zinc alloys with aluminum content from 25 to 40% (wt.) and composites based on them and containing 5% (wt.) of titanium in the form of dispersed intermetallic compounds. Regression equations for friction coefficient and wear resistance depending on aluminum and titanium contents in experimental alloys were obtained by the method of mathematical design of experiment. Adding of powder titanium improves the tribological properties of castings due to the formation of heterophase structure. Titanium aluminides in composite, based on ZA27 alloy, are presented as uniformly distributed compact block form crystals with an average size 22,19+5,5 μm. Increasing of aluminum content in composite alloy up to 40% (wt.) leads to the growth of Al₃Ti intermetallic particles size up to 100–120 μm and changes their morphology to a plate-like one, which increases the friction coefficient and reduces the wear resistance. The best tribological properties in the testing conditions has a composite alloy ZA27 + 5 % (wt.) Ti with 25–30% less friction coefficient under lubricated conditions compared to the matrix alloy and superior it in wear resistance by more than seven times. Obtained results allow making recommendations for using developed zinc composite alloys for the manufacture of castings for antifrictional purposes working under lubricated conditions.
This work was carried out with the support of the Ministry of Education and Science of Russian Federation within the universities' state task in the sphere of scientific activity for 2014–2016.

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