Influence of Al and Y content on the oxidation resistance of CrAlYN protective coatings for high temperature applications: New insights about the Y role

Abstract

CrAlYN hard coatings with two different average Al contents: 16 at.% and 25 at.%, and Y concentration varying between 1.2 and 5.7 at.% were deposited by direct current reactive magnetron co-sputtering of mixed Cr-Al and Y targets on commercial M2 steel substrates. The samples were heated to 1000 ºC in air during 2 h to study their oxidation resistance and thermal stability. The Y content is critical and the coatings present different behaviour depending on the Al content. The best oxidation resistance and thermal stability are obtained for the coating with 16 at.% Al and 3.4 at.% Y. The initial film microstructure and the cubic phase (fcc-CrAlN) were retained, and a thin (Cr,Al) 2 O 3 oxide protective scale was formed. At lower Y content (1.2 at.%) iron from the substrate crosses the coating, while a higher content (4.6 at.%) avoided the iron diffusion at the expense of a thicker oxide scale with new oxide phases. The coatings with higher Al content (~25 at. %) were not thermally stable at 1000ºC. A good oxidation resistance was obtained for 2.6 at.% of Y although new phases (hcp-AlN and Cr-Fe) were formed. Higher amount of yttrium (5.7 at. %) led to the complete oxidation of the coating.

Effect of target power on the structure and tribological Properties of La-Ti/WS2 composite films prepared by unbalanced magnetron sputtering

“…At this time, the growth rate of composite film was faster, as it was found in similar composite films [14]. However, with the increase of sputtering power of La-Ti target, it can be seen from figures 1(b)-(e) that the surface of composite films are granular island structure, the crack between particles were reduced, and the films are denser, it had special electronic layer structure and chemical activity with the rare earth element La, and it was easy to gather and enrich to the grain boundary [15]. It could form stable compounds with the impurity elements such as hydrogen and oxygen, which could inhibit the growth and coarsening of grain and increase the nucleation rate.…”

Quo Vadis: AlCr-Based Coatings in Industrial Applications

“…A further study of co-sputtered coatings containing Y showed that excellent oxidation behaviour was achieved with a Y content of 3.4 at.% for Cr-rich Cr 25.8 Al 15.3 Y 3.4 N 55.5 coatings, whereas for Al-rich coatings, a lower Y content of 2.6 at.% was the best with Al 24.9 Cr 18.1 Y 2.6 N 54.4 . It was also found that higher Y contents promote the hcp phase formation [112].…”

Enhancement of the Ti‐6Al‐4V alloy corrosion resistance by applying CrN/CrAlN multilayer coating via Arc‐PVD method

“…In this regard, multicomponent and multilayer coatings have been studied; by producing CrAlN, TiCN, TiAlN, and TiCrAlN new coatings, a significant step has been taken toward the development of hard and corrosion‐resistant coatings 7‐10 . Addition of aluminum to transition metal nitrides has led to a new group of hard coatings improving oxidation and corrosion behavior, thermal stability, and their hardness 11‐16 . Triple nitride coatings on the Cr base can prevent oxygen diffusion into the coating by forming dense protective oxides like Cr 2 O 3 and Al 2 O 3 , improving the corrosion properties of the coating.…”

“…7-10 Addition of aluminum to transition metal nitrides has led to a new group of hard coatings improving oxidation and corrosion behavior, thermal stability, and their hardness. [11][12][13][14][15][16] Triple nitride coatings on the Cr base can prevent oxygen diffusion into the coating by forming dense protective oxides like Cr 2 O 3 and Al 2 O 3 , improving the corrosion properties of the coating. Also, chrome oxide layers are denser than titanium oxide layers, so nitride coatings on the chromium base can have a higher corrosion resistance.…”