S. Y. Hwang, H. Yang, RIST, Pohang, South Korea; C. Lee, Hanyang University, Seoul, South Korea; J. Cho, Hanyang Univ., Seoul, South Korea
As a recent progress of nano-structured materials, thermal spraying is one of the most interesting areas that enhance the surface properties while conventional matrixes are used. A few improved surface properties are improved hardness and wear resistance. In this study, recent progressed results of two kinds of nanostructured thermal sprayed coatings are presented in this paper. One is a WC-based coating, and the other is a solid lubricant coating.
For nanostructured WC-Co coatings, improved wear resistance of the coatings were shown after heat treatment. Nanostructured WC-Co coatings prepared by HVOF spraying were heat-treated under various temperatures and heat treatment duration time and different gas environments. The influence of the post heat-treatment was discussed in terms of changes in microstructure, composition and hardness of the coatings. These results demonstrate that the wear resistance of the nanostructured WC-Co coatings can be improved by a proper post heat-treatment process and shown via scratch tests.
For the solid lubricant coating, a new feed stock powders such as NiCr-based composition powders including nano Cr2O3 were used through a spray drying method. Microstructure and mechanical properties of the nano Cr2O3 containing coatings were evaluated and compared with a blended feedstock. The application results of the coatings in an air foil bearing will be also presented.
Summary: As a recent progress of nano-structured materials, thermal spraying is one of the most interesting areas that enhance the surface properties while conventional matrixes are used. A few improved surface properties are improved hardness and wear resistance. In this study, recent progressed results of two kinds of nanostructured thermal sprayed coatings are presented in this paper. One is a WC-based coating, and the other is a solid lubricant coating.
For nanostructured WC-Co coatings, improved wear resistance of the coatings were shown after heat treatment. Nanostructured WC-Co coatings prepared by HVOF spraying were heat-treated under various temperatures and heat treatment duration time and different gas environments. The influence of the post heat-treatment was discussed in terms of changes in microstructure, composition and hardness of the coatings. These results demonstrate that the wear resistance of the nanostructured WC-Co coatings can be improved by a proper post heat-treatment process and shown via scratch tests.
For the solid lubricant coating, a new feed stock powders such as NiCr-based composition powders including nano Cr2O3 were used through a spray drying method. Microstructure and mechanical properties of the nano Cr2O3 containing coatings were evaluated and compared with a blended feedstock. The application results of the coatings in an air foil bearing will be also presented.
