Improving the Properties of Composite Titanium Nitride Layers on the AZ91D Magnesium Alloy Using Hydrothermal Treatment

Abstract

Coating magnesium alloys with nitride surface layers is a prospective way of improving their intrinsically poor surface properties; in particular, their tribological and corrosion resistance. These layers are usually produced using PVD methods using magnetron sputtering or arc evaporation. Even though the thus-produced layers significantly increase the wear resistance of the alloys, their effects on corrosion resistance are unsatisfactory because of the poor tightness, characteristic of PVD-produced products. Tightness acquires crucial significance when the substrate is a highly-active magnesium alloy, hence our idea to tighten the layers by subjecting them to a post-deposition chemical-hydrothermal-type treatment. This paper presents the results of our experiments with a new hybrid surface engineering method, using a final tightening pressure hydrothermal gas treatment in overheated steam of the composite titanium nitride layers PVD, produced on AZ91D magnesium alloy. The proposed method resulted in an outstanding improvement of the performance properties, in particular resistance to corrosion and wear, yielding values that exceed those exhibited by commercially anodized alloys and austenitic stainless 316L steel. The developed hybrid method produces new, high-performance corrosion and wear resistant, lightweight magnesium base materials, suitable for heavy duty applications.

Improved Surface Quality with TiN‐Coated Tool

“…The small white particles observed on the surface of the coated tool are associated with the presence of the TiN compound. [9,10] In Figure 2b, it can be observed that there are white droplets and pits on the surface of the TiN coating. This is due to the intrinsic characteristics of the deposition technique.…”

“…The small white particles observed on the surface of the coated tool are associated with the presence of the TiN compound. [ 9,10 ]…”

Corrosion and Wear-Resistant Composite Zirconium Nitride Layers Produced on the AZ91D Magnesium Alloy in Hybrid Process Using Hydrothermal Treatment

“…Any violation of the continuity of the layer under the influence of mechanical factors, similar to the natural, leaking defects of the structure, will result in the formation of corrosion microcells and, as a result, accelerated destruction of the layer as a result of galvanic corrosion. Therefore, in order to ensure the service life of products made of magnesium alloys exposed to corrosion, apart from corrosion resistance, high mechanical resistance is also required [23]. Therefore, a number of mechanical tests were performed.…”

“…In particular, the main objective of the study was to verify the susceptibility of zirconium nitride-based layers to hydrothermal sealing. The origin of the concept of final sealing of zirconium nitride composite layers was in earlier works on the hybrid production of tight, highly resistant to corrosion and wear, TiN-Ti-Al titanium nitride composite layers, which showed outstanding effectiveness [21,23,24].…”

Preparation of corrosion-resistant surface of magnesium alloy and its performance study

“…Heated to a certain pressure and temperature in the reactor, water molecules will gain some activity, which can react with some active metals. Through the chemical reactions, a hydroxide film layer can be directly formed on the alloy surface [19]. The film layer can prevent corrosion, avoiding the corrosion of the metal substrate by external media to a certain extent.…”