CHEMICAL PRE-TREATMENT OF MECHANICALLY MILLED RECYCLED HARDMETAL POWDERS

摘要

The present research concentrated on chemical pre-treatment of recycled powders bathed in acid media. Influential factors including concentration, submerging time, solution composition, cleaning conditions (magnetic or ultrasonic agitation) and temperature were studied in detail. Results showed the importance of chemical pre-treatment process. Sulphuric acid was selected as a suitable reagent as it is readily available, affordably priced and highly reactive. Furthermore, sulphuric acid did not dissolve the cobalt binder in WC-Co as compared to many other concentrated acids. Hardfacings produced from pretreated recycled powders showed an improved quality with almost no surface defects.