A special coating technique, electro-spark deposition (ESD), was developed to produce micro-crystalline ODS MGH754 alloy coatings on a commercial ICrl8NigTi stainless steel and a cast Ni20Cr alloy substrates. The coatings have a very fine grain structure and metallurgical bonding with the substrates. The isothermal oxidation tests at 1000 ℃ in air showed that the micro-crystalline ODS alloy coatings had a much reduced oxidation rate and improved scale spallation resistance compared with the uncoated alloys. The selective oxidation of Cr was greatly promoted to form protective and continuous Cr2O3, scales on the alloy surface. Micro-crystallization and oxide dispersions have synergistic effects on the improvement of oxidation resistance. The beneficial effects were discussed based on the experimental results.
A new technique - series electro-pulse discharge (SEPD) - was developed as a sur-face coating process. In this technique, both positive and negative poles of a pulsepower were used as the depositing electrodes with the substrate alloy as an induction electrode. Fe-Cr and Fe-Cr-Y2 O3 micro-crystalline coatings were deposited on stain-less steel (Fe-18Cr-8Ni) surfaces. Oxidation at 950℃ in ambient air showed that the coatings greatly improved the oxidation resistance of the steel. The addition of dis- persed Y2O3 nano-particles into the alloy coatings was found to further reduce the scaling rate and enhance the adhesion of oxide scales.
Q. Xu,Y.D. He,D.R. Wang,H.B. Qi,Z.W. Li and W.Gao Beijing Key Laboratory for Corrosion, Erosion and Surface Technology, University of Science and Technology Beijing, Beijing 100083, China Department of Chemical and Material Engineering, The University of
