Ritošā sastāva metālpulveru antifrikcijas detaļu ražošanas tehnoloģija un tribotehnisko īpašību paaugstināšana

The doctoral thesis “Production Technology of Metal Powder Antifriction Parts for Rolling Stock and Improvement of Their Tribological Properties” has been worked out in order to research the production technology of metal powder antifriction parts and perform experimental tests with the purpose to determine the suitability of metal powder antifriction parts with low alloying element content to use in the brake lever mechanism of rolling stock, as well as to perform with them tests in order to reduce the friction coefficient.

Analyses for tribological estimate and testing with a non-destructive test of the parts in production is performed within this thesis. Suitability of ultrasound and radiography methods to quality estimate of porous materials is shown. Techniques of static and dynamic pressure by using impulse magnetic field are reviewed. Mechanical treatment parameters to ensure surface roughness quality of the treated part is experimentally determined. Recommendations for impregnation with lubricant containing WS2, WSe2 nanoparticles to reduce the friction coefficient are proposed.

The results of research performed within this doctoral thesis show that powder metallurgy products have a specific range of properties allowing to apply them in production of various construction materials, and they are safe when producing antifriction parts. Mass fraction of alloying elements on the iron basis, such as Ni and Mo, when producing antifriction bushes for the brake lever system of a car, may be reduced because the experimental parts made attested the conformity with the requirements for installing them in the pin joints of the brake lever mechanism of a car. Using low-alloyed materials in the production of antifriction parts allows to obtain higher efficiency indexes with no impact on the movement safety. Additionally, the thesis contains studies showing opportunity to improve tribological properties of antifriction powder materials by impregnating them with nanoparticles, thus, reaching safer resistance and exploitation characteristics of antifriction parts.

The doctoral thesis is based on the scientific articles published by the author, analyses of powder metallurgy theoretical processes, and experimental tests with metal powder antifriction materials. This doctoral thesis, as a composition of scientific publications, has been drafted in Latvian and consists of introduction part, four chapters, conclusion part, bibliography part, 69 images, 16 tables, 8 annexes, and 151 pages in total. The bibliography part contains 101 titles.