• Journal of the Korean Chemical Society
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• v.49 no.2
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• pp.129-137
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• 2005

• Journal of Powder Materials
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• v.21 no.2
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• pp.93-96
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• 2014

Cobalt coated tungsten carbide-cobalt composite powder has been prepared through wet chemical reduction method. The cobalt sulfate solution was converted to the cobalt chloride then the cobalt hydroxide. The tungsten carbide powders were added in to the cobalt hydroxide, the cobalt hydroxide was reduced and coated over tungsten carbide powder using hypo-phosphorous acid. Both the cobalt and the tungsten carbide phase peaks were evident in the tungsten carbide-cobalt composite powder by X-ray diffraction. The average particle size measured via scanning electron microscope, particle size analysis was around 380 nm and the thickness of coated cobalt was determined to be 30~40 nm by transmission electron microscopy.

• Applied Chemistry for Engineering
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• v.23 no.6
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• pp.583-587
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• 2012

Six kinds of new aminoalkyl phosphonic acid or aminoalkyl phosphinic acid derivatives with mono-dialkylamino, or di-dialkylamino functional groups in the molecule were synthesized and their smoke densities were tested. The aminoalkyl phposphonic acid or aminoalkyl phosphinic acid derivatives were synthesized with quantitative yields of 90~98.6% by one step reaction of the phosphorus acid or hypo phosphorous acid with amine and aldehyde. The smoke density was measured by the ASTM E 662 method. Values of the smoke density were obtained from 224.5 to 256.6. The smoke density of the compounds with two aminoalkyl structures decreased more than that of compounds with one aminoalkyl structure. In addition, there was no correlation between the smoke density and the number of carbon atoms in the alkyl group attached to the amino group.