Nano-composite coatings with improved mechanical properties and corrosion resistance by thermal spraying

This paper reports the synthesis and characterization of nanostructured coatings. To improve the mechanical properties and oxidation resistance of the materials, two new types of nanostructured coatings including CoNiCrAlY-MoSi/sub 2/ and Ni60-TiB/sub 2/ were designed. The nanocrystalline feedstock powders were prepared by high energy ball milling (HEBM). The particle size, morphology and grain size of the feed stocks were investigated. The preparation, microstructure, mechanical properties, and anti-oxidation behavior of the nanostructured CoNiCrAlY-MoSi/sub 2/ and Ni60-TiB/sub 2/ coatings are presented. With a lamellar and compact structure, the optimized nano-composite CoNiCrAlY-MoSi/sub 2/ coatings is metallurgically bonded with the substrate. It exhibits low porosity, high fracture toughness and excellent thermal shock resistance. The nanostructured Ni60-TiB/sub 2/ composite coatings also exhibited better mechanical properties and wear-corrosion resistance than those of its conventional counterpart. This work is expected to play an important role in the preparation and application of high performance nanostructured coatings. (author)