Nanopowder dispersion and spray-drying process: The case of Cr 2O3
Résumé
The work reported in this paper was performed in order to develop and to optimize the dispersion of Cr2O3 nanopowders by a ball-milling method and to produce spherical micrometer-sized granules by spray-drying. The targeted application for such granules is the development of wear resistant nanostructured Cr2O3 coatings by plasma spraying. Cr2O3 nanopowders were dispersed in deionized water. The suitable dispersant (DarvanC) was determined by zeta potential measurements and the dispersant quantity was optimized by rheological tests. The influence of milling time, diameter of milling balls and weight ratio of milling balls to powder was studied by granulometric measurements. A well-dispersed and stable suspension was then obtained and spray-dried. Dense and spherical micrometer-sized granules, with a monodispersed distribution centered about 50 µm, have been achieved and Cr2O3 plasma-sprayed coatings have been realized.