engleski

Influence of powdered silicion particle size on its thermal behaviour

Powdered silicon plays an important role as a fuel in pyrotechnics. The burning characteristics of pyrotechnic mixtures based on silicon, as well as some other important characteristics, depend strongly on powdered silicon particle size and distribution. Influence of silicon particle size on thermal behaviour of four different silicon samples was studied in this work by thermogravimetric analyser (TGA) and differential thermal analyser (DTA). TGA and DTA measurements were carried out under isothermal and non-isothermal conditions. Measurements were made using samples weighing 0.5-6 mg, and different purging gas atmosphere. It was found out that at temperatures above 800 oC silicon powder oxidises even by small amount (obou 2 %) of oxygen present in surrounding gas atmosphere. Slow oxidation rate in temperature range 800 – 1300 oC depends on silicon sample particle size, i.e. on sample specific area. The rate of silicon oxidation above 1300 oC increases rapidly, however it was found that at higher temperatures the rate of oxidation does not depend so strongly only on silicon sample particle size. Melting temperature of silicon (~ 1410 oC) can be obtained by DTA measurements only when higher heating rates are used (~ 50 oC/min), since under slower heating rates silicon oxidises completely below melting. It was found out that the melting temperature does not depend considerably on sample size, but depend strongly on silicon sample mass.

powdered silicion; thermal properties

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