New anti-friction aluminum alloys for cast monometallic plain bearings. Bench tests

Abstract

The work was carried out with the financial support of the Ministry of Education and Science of the Russian Federation under the Agreement No. 074-11-2018-011 of May 31,2018 on the topic: "Development and organization of high-tech production of innovative electric heating systems for inter-industry use with breakthrough performance" in the framework of the implementation of the RF Government decree No. 218 dated April 09, 2010. The article presents aluminum antifriction alloy from a series of newly developed alloys to replace bronzes for monometallic plain bearings. Complex alloyed aluminum alloys are developed using methods of nonequilibrium thermodynamics and the theory of selforganization. According to the results of applying nonequilibrium thermodynamics and the theory of self-organization to the friction process, the wear rate of rubbing bodies can decrease several times as the self-organization passes through the tribosystem and dissipative structures form. Complex alloying facilitates self-organization. Self-organization is determined by the intense occurrence of physicochemical processes with negative entropy production, i.e. such processes proceed in the direction of increasing free energy. Self-organization is expressed in the formation of the necessary secondary structures. The complexity of the system in our case was increased due to an increase in the complexity of antifriction materials, i.e. increase in the number of alloying elements. The results of the study of secondary structures on the friction surface of antifriction aluminum alloys are presented. The differences in the compositions and microstructure of secondary structures from the composition and microstructure of the alloy to friction are shown. The role of various chemical elements in the formation of the necessary secondary structures is discussed. Chemical elements could get into secondary structures from an antifriction alloy, steel counterbody, lubricant, atmosphere. The mechanical and tribological properties of aluminum alloys are determined. The properties of aluminum alloys with bronzes are compared. Aluminum antifriction alloys, inferior to bronzes in mechanical properties, significantly surpass them in tribological properties. Aluminum alloys are 6 times smaller than bronze, wear a steel counterbody; the load of the seizure of aluminum alloys is 2.5 times the load of the seizure of bronze; the wear rate of aluminum alloys is 2 times less than the wear rate of bronze. A pilot batch of monometallic plain bearings was manufactured from the new alloy and bench tests were carried out for comparison with bronze bearings. The bench test results confirmed the advantages of aluminum alloy over bronze, given that the lubrication and cooling conditions of aluminum bearings were more stringent than the conditions for lubricating bronze.