Studying the Physical Processes of Forming the Adhesive Strength of Bimetallic Bearing for Marine Engineering

Abstract

The results of a metallographic analysis of a bimetallic bearing assembly for hull parts of marine engineering are presented in the paper. The adhesive properties at the Al-Fe metal boundary are poorly studied at present; the physical processes of strength formation are very heterogeneous and depend on the parameters of the technological process. The samples obtained by stamping a commercial liquid Al-Si-Mg alloy in the presence of powder bush from a pure iron with 15 percent volume porosity have been studied in the paper. Metallographic analysis is performed using a Carl Zeiss Axiovert 200 MAT motorized optical microscope equipped with a Thixomet Pro image analyzer. Samples with different levels of adhesive strength, from unsatisfactory to the highest values, are selected for the research. The strength value correlates well with technological parameters such as stamping pressure and the temperature of preheating of the forming rigging. However, it was found that the mechanisms of Al and Fe compound are different. At low stamping pressures and poor adhesion strength of the compound, the main reason for the lack of contact at the metal boundary is a strong temperature gradient and various rates of shrinkage processes that sever the contact zone. Under conditions of medium stamping pressures, liquid aluminum destroys the ferrite network of the powder bush and penetrates into free pores to a depth of 1-2 mm, forming a high-quality adhesive compound. The bimetal boundary zone has a high density, finely dispersed structure of aluminum without traces of graphite, and the powder bush contains all the signs of secondary crystallization in the form of network structure of a ferrite. Under conditions of high stamping pressures, liquid aluminum interacts with iron, forming metastable intermetallic phases at the metal interface, while aluminum also penetrates into the pores of the ferrite network. The presence of intermetallic compounds increases the adhesive strength of the compound. New physical principles aimed at finalizing the technology for obtaining the bimetallic bearing of marine engineering at the stage of obtaining a workpiece have been identified and disclosed.Keywords: bimetallic bearing, metallographic analysis, marine engineering, adhesive strength. For citation:Kuznetsov, Ruslan V., and Evgeniy O. Olhovik. "Studying the physical processes of forming the adhesive strength of bimetallic bearing for marine engineering." Vestnik Gosudarstvennogo universiteta morskogo i rechnogo flota imeni admirala S. O. Makarova 11.5 (2019): 902-909.В данном исследовании приводятся результаты металлографического анализа биметаллического подшипникового узла для корпусных деталей судового машиностроения. Отмечается, что в настоящее время адгезионные свойства на границе металлов Al-Fe слабо изучены, физические процессы формирования прочности весьма разнородны и зависят от параметров технологического процесса. В работе изучены

Technology for producing wear-resistant bimetal bearing based on cast aluminum

“…To implement this task in this work, the authors conducted studies on the possibility of using the technology of joint stamping of liquid metal (SLM) [9][10][11] and sintered powder material. Samples for the study were prototypes of bimetal plain bearings with an outer diameter of 61mm and height of 14mm.…”