Establishment of processing facilities for surface modification of powders

Facilities were established for surface modifications of powder materials. In this connection, various fluidized bed reactors capable of operating at different temperatures were fabricated indigenously and different powders were successfully coated with carbon and different metals. Cobalt acetylacetonate was used as precursor material for coating of tungsten carbide (WC) and Al/sub 2/O/sub 3/ powders with cobalt (Co) in a temperature range of 475-500 deg. C. Argon was used as a carrier gas at a flow rate of 3 L min/sup -1/. Cobalt films of varying thickness were deposited (5 to 20 mu on WC and 1 to 5 mu on Al/sub 2/O/sub 3/) by varying the run time from 45 to 60 minutes. Scanning electron microscopy (SEM) images and energy dispersive (ED) spectra of coated powders are shown. Using methyl trichloro silane (MTS), graphite powder was coated with SiC at 1150 deg. C, with a gas flow rate of 0.25-0.5 L min/sup -1/. For achieving coatings of different thickness, runs from 20-25 minutes were carried out. SiC powder was collected as a byproduct of the reaction. (orig./A.B.)