A new MAX phases-based electroconductive coating for high-temperature oxidizing environment

In the paper, results of variations of structure, oxidation resistance, and electrical conductivity of novel MAXphase composite coating are presented. The characteristics of highly dense Ti-Al-C composite bulks and vacuum-arc deposited 6 mu m thick coatings before and after heating at 600 degrees C in air for 1000 h were compared. High electrical conductivity (sigma = 1.3.106 S/m) of the highly resistant toward oxidation (Delta m/S = 0.07 mg/cm2) Ti-Al-C coating was preserved after long-term heating in air. It was found that the specimen surface layers of MAX-phases Ti3AlC2 and Ti2AlC based bulks and chromium-containing Crofer 22APU steel became semiconductors because of high-temperature long-term oxidation (at 600 degrees C). The vacuum-arc deposited Ti-Al-C composite coating revealed high oxidation resistance and electrical conductivity along with good mechanical characteristics, namely nanohardness H (10 mN) = 9.5 +/- 1.5 GPa, and Young's modulus E = 190 +/- 10 GPa, which make it very promising for interconnects of solid oxide fuel cells (SOFCs).

Automated summary

This paper presents the results of variations in structure, oxidation resistance, and electrical conductivity of a novel MAXphase composite coating. It demonstrates that the Ti-Al-C coating maintains high electrical conductivity and oxidation resistance even after long-term heating in air. The study also reveals that specimen surface layers of MAX-phases and chromium-containing steel become semiconductors due to high-temperature long-term oxidation.