Increasing the wear resistance of Al-Mg components using thermal-spray coatings

Abstract

In the present work, plasma-spray technology was applied as a means to improve the durability of Al-Mg alloy parts. NiCrSiBFe coatings deposited on aluminium-magnesium alloy substrates with different thickness values were studied. Before spraying, the surfaces of aluminium-magnesium alloy were modified upon applying different surface pre-treatment methods. The phase composition, microstructure, microhardness, porosity and adhesion of the deposited coatings were characterized. Ball-on-plate wear tests of the NiCrSiBFe coatings were carried out in dry and lubricated conditions, using a scanning electron microscope to characterize the worn track and the wear mechanism. The correlation of the coating porosity and the adhesion strength with the thickness of a deposited layer was determined. The results revealed that the plasma-sprayed NiCrSiBFe coatings, compared with the uncoated Al-Mg substrate, provide both a stable friction coefficient and an improved wear resistance, which is about two times better under dry sliding and about five times better under lubricated sliding.

V prikazanem delu je bila za izboljšanje trajnosti delov iz Al-Mg zlitin uporabljena tehnologija pršenja s plazmo. Predmet preučevanja so bile NiCrSiBFe prevleke nanesene na podlago iz aluminij-magnezijevih zlitin. Pred nanašanjem so bile površine aluminij-magnezijevih zlitin obdelane z različnimi postopki predpriprave površin. Določene so bile fazna sestava, mikrostruktura, mikrotrdota, poroznost in oprijem napršenih prevlek. Za določitev sledi obrabe in mehanizma je bil na NiCrSiBFe prevlekah izveden preizkus s kroglico, v suhih in naoljenih pogojih, in bil karakteriziran s pomočjo vrstičnega elektronskega mikroskopa. Določena je povezava med poroznostjo in jakostjo oprijema ter debelino nanešenega sloja. Rezultati so pokazali, da plazemsko napršene NiCrSiBFe prevleke v primerjavi z Al-Mg zlitino brez prevlek, omogočajo stabilen koeficient trenja in izboljšujejo odpornost, ki je dvakrat boljša pri drsenju po suhi podlagi, in petkrat boljša pri drsenju po naoljeni podlagi.