Report on industrial attachment with Advanced Technology Research Centre : processing and characterization of oxidizer-coated metal powders

Abstract

In the processing of oxidizer-coated fuel, a co-spray drying of a feed mixture of Al and NaNO2 (in solution) was carried out. The process parameters (Table 1) adopted was derived from an optimized process condition for the spray drying of 1%w/v of NaNO2 which resulted in spherical clusters of NaNO2 of relative uniform particle size range of 80 to 150 μm. Both spherical Al of 3.84μm (NHY130) and granules Al of 15μm (NHY100) were used in separate co-spray drying processes to study the effect of the difference in morphology of Al used on the resulting morphology of the co-spray dried products.

As a result, spherical clusters of Al and NaNO2 of particle size range of 174 – 326 μm were produced from the usage of both NHY130 and NHY100 in feed formulations of Al: NaNO2 = 1:9, 3:7 and 1:1 weight ratios. The only difference between the usages of different Al was that spherical clusters of 1S1 were of bigger particle size than that of 1N1, which was due to the formation of hollow structures in 1S1. (Table 2) This phenomenon was attributed to the much smaller size of the Al particles (5μm) used as compared to the spray dried NaNO2 of about 100μm.