In the present work, we successfully prepared the single-layer, double-layer and multilayer CrAlN coatings. The crystal structure, high temperature oxidation and hot corrosion behaviors of the coatings were studied. The following conclusions were drawn:
(1) Cr1-xAlxN (0≤x≤1) coatings with different Al contents were prepared successfully by a reactive magnetron sputtering method. The phase segregation mechanism of the metastable c-AlN and the influence of the phase segregation on the critical failure load were discussed.
(2) The oxidation and hot corrosion behaviors of Cr0.50Al0.50N coating were investiged. The coating demonstrated excellent resistance to the oxidation at 900-1100 oC.
(3) The double-layer coatings of CrN/CrAlN demonstrated much better resistance to hot corrosion. However, the cyclic oxidation resistance of the double-layer coatings was not as good as that of single-layer coating.
(4) The multilayer CrAlN coating provided good protection against many types of high temperature corrosion, i.e., high temperature oxidation and hot corrosion. The outer Al-rich layer gave the coating good oxidation protection at 950-1100 oC due to the formation of a continuous alumina scale. The intermediate Cr-rich layer can form a chromia scale to provide good protection under the hot corrosion conditions at 900, 950 and 1000 oC. Meanwhile,the multilayer coating presented excellent resistance against cyclic oxidation.
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