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Temperaturowa odporność na zużycie elementów z powłoką AlCrN

Michalak M., Michalczewski R., Osuch-Słomka E., Szczerek M.

Inżynieria Materiałowa

2015

Vol. 36, nr 6

468--472

Celem pracy było zbadanie wpływu temperatury na odporność na zużycie elementów pokrytych powłoką AlCrN. Powłokę wytworzono w procesie osadzania fizycznego z fazy gazowej (PVD) na tarczach wykonanych z węglika wolframu. Badania tribologiczne w ruchu ślizgowym ciągłym przeprowadzono z wykorzystaniem stanowiska badawczego T-21 produkcji ITeE–PIB. W wyniku przeprowadzonych badań stwierdzono, że odporność na zużywanie skojarzenia z powłoką AlCrN zależała od temperatury. Największe zużycie odnotowano w temperaturze pokojowej. Natomiast w 600°C intensywność zużywania powłoki była 4-krotnie mniejsza, a w 750°C 6-krotnie mniejsza niż w temperaturze pokojowej. Mechanizm wysokotemperaturowej odporności na zużywanie powłoki AlCrN polega na utworzeniu tlenkowej warstwy ochronnej. Przeprowadzone analizy składu warstwy wierzchniej wskazały na znacznie większą zawartość tlenu w śladzie tarcia niż poza śladem. W wysokiej temperaturze proces tarcia dodatkowo intensyfikował utlenianie, a ilość tlenu wzrastała wraz ze wzrostem temperatury.

The aim of the study was to investigate the effect of temperature on the wear resistance of coated parts AlCrN. The coating was prepared in the physical vapour deposition process (PVD) on the discs made of tungsten carbide. The testing in sliding motion conditions was performed using T-21 tribotester manufactured by ITeE–PIB. The results showed that the wear resistance of the AlCrN coating depends on the temperature. The largest wear rate was obtained at room temperature. In contrast, at 600°C the intensity of wear of the coating was 4-fold lower, and 750°C, 6-fold lower than at room temperature. The mechanism of high wear resistance of AlCrN coating is based on creation of oxide protective layer. Conducted analysis of the composition of the surface layer showed a significantly higher content of oxygen in the wear track than the outside track. At high temperature, friction process further intensified oxidation and the amount of oxygen increased with increasing temperature.

Evaluation of an AICrN coated FSW tool

Batalha G. F., Farias A., Magnabosco R, Delijaicov S., Adamiak M., Dobrzański L.A.

Journal of Achievements in Materials and Manufacturing Engineering

2012

Vol. 55, nr 2

607--615

Purpose: This paper aims to evaluate the wear performance of a physical vapor deposition (PVD) coating on cemented carbide (WC) tool used in friction stir welding FSW processing of Ti alloy sheets. Design/methodology/approach: A coating of AlCrN material was applied to a WC tool in order to increase its wear resistance, thermal shock stability and hot hardness. In comparison to the conventional coatings, the AlCrN coating system had a higher resistance to abrasive wear as well as higher hot hardness and oxidation resistance. FSW processing of Ti with a coated WC tool was expected to have better performance than an uncoated tool. Back Scattering Electron (BSE) imaging mode at scanning electron microscope was used to determine the main mechanism of tool wear, which was found to be hot adhesion and inter-diffusion of tool constituents with the workpiece materials. Findings: The tool degradation was evaluated by scanning electron microscopy in order to observe the main tool wear mechanism. The real contribution of the (Al,Cr)N coating layer could not be correctly evaluated, since there is no residual trace of its components at the worn tool. What was probably found left from the coating layer was the N component which formed the nitride TiN observed by EDS mapping. The parameter conditions were probably too severe, overcoming the layer limit strength. Research limitations/implications: The research were carried out as a preliminary evaluation and this initial results in the need of a further analysis that should be performed looking for a suitable tool material and coating optimization for the FSW processing of titanium alloys. Practical implications: Despite being successfully used in other manufacturing applications like machining operations in which friction and temperature are also high, the WC tool material and the coating had an unsatisfactory wear resistance, and the AlCrN coating was totally worn during the FSW processing. This suggests that new materials and coatings are still needed for FSW tools. Originality/value: FSW process is gaining importance as an industrial joining method, but the tool wear is still an important challenge to achieve efficient and economic operation. Because of the low thermal conductivity and high chemical reactivity of Ti, tools wear rapidly due to high temperature and strong adhesion. In order to achieve higher processing speeds, reducing heat at the interface tool/work material is required, as is the use of tool materials that have little or no chemical affinity.