The study of antifriction aluminum alloys containing iron, before and after tribological tests

Abstract

Experimental aluminum alloys with the addition of iron, which model the materials obtained with the addition of recyclables, were investigated. The use of the recyclable (silumin waste, production waste, remelting of canned scrap, etc.) seems to be promising for the national economy. In the work, the alloy of the Al-6 % Sn-5 % Si-4 % Cu (mass. %) system was used as a base, to which iron (1 %) and other elements (bismuth, lead, manganese) were added. The samples under investigation were subjected to heating up to 500°C and cooling in various regimes. It was shown that the best results were achieved with cooling in water: the phases were spheroidized and properties were improved. Complex method of microscopy, including optical, electronic (with X-ray spectral microanalysis), and probe microscopy was used, in order to study alloys before and after tribological tests. An investigation of the initial structure of the samples showed that the combined addition of iron with manganese (0.5 %) led to the formation of favorable skeletal phases. The tribological tests without lubrication which modeled the extreme conditions of operation were carried out. These experiments showed that the investigated alloy had an increased wear resistance, which could be associated with the formation of skeletal phases. After tribological tests, significant changes in the structure and phase components at the surface and in the near-surface layer were observed. For the study of this layer, an oblique cut was made, on which near-surface area with a thickness of 50-100 μm was detected.

Features of the Formation of Surface Structures under Dry Friction of Al-30Sn Composite against Steel

“…Hence, antifriction materials should have an effect of self-lubrication, which consists of supply of the soft phase on the friction surface. A protective layer of the formed secondary structures acts as a solid lubricant in critical conditions of friction (dry friction, shock loads) and prevents a fracture of the shaft [20]. According to this view, the sintered Al-30Sn composite can be considered as a prospective antifriction material because it contains a lot of soft phase.…”