Surface layers on the Mg-Al-Zn alloys coated using the CVD and PVD methods

Purpose: The aim of this paper was investigated structure and properties of gradient coatings produced in PVD and CVD processes on MCMgAl9Zn1 magnesium alloys. Design/methodology/approach: The following results concern the structures of the substrates and coatings with the application of electron scanning microscopy ZEISS SUPRA 35; phase composition of the coatings using X-ray diffraction and grazing incident X-ray diffraction technique (GIXRD); microhardness and wear resistance. Findings: The deposited coatings are characterized by a single, double, or multi-layer structure according to the applied layers system, and the individual layers are coated even and tightly adhere to the substrate as well to each other. The analysis of coatings obtained on the surface of cast magnesium alloys by the PVD and CVD processes show a clear - over 100% - increase of the microhardness, compared to the base material microhardness. The best results of the sliding distance were obtained for the DLC coatings. Practical implications: Achieving of new operational and functional characteristics and properties of commonly used materials, including the Mg-Al-Zn alloys is often obtained by heat treatment, ie, precipitation hardening and / or surface treatment due to application or manufacturing of machined surface layer coatings of materials in a given group of materials used for different surface engineering processes. Originality/value: The paper presents the research involving the PVD and CVD coatings obtained on an unconventional substrate such as magnesium alloys. Contemporary materials should possess high mechanical properties, physical and chemical, as well as technological ones, to ensure long and reliable use. The above mentioned requirements and expectations regarding the contemporary materials are met by the non-ferrous metals alloys used nowadays, including the magnesium alloys.