Determination of the Possibility of Regulating the Specific Surface Area of Iron (Iii) Oxide in Self-Propagating High-Temperature Synthesis in Solution

The dispersibility of components is one of the most important characteristics of bulk materials. Iron oxide (III) is a widely used powder, the specific surface area and disperse composition of which affects the scope of its application. One of the methods for obtaining ultra and nanodispersed Fe2O3 is self-propagating high-temperature synthesis (SHS) in solutions, where mixtures of iron (III) nitrate nonahydrate as an oxidizer and glycine as a fuel are used as the basic components. Depending on the concentration of the solution, SHS can be carried out in two modes: thermal explosion; self-propagation mode (regular motion of the combustion wave along the sample). This article shows that synthesis in the self-propagation mode is possible when 24-33% of the mass of Fe(NO3)3 9H2O is removed by drying, which makes it possible to obtain a product with a specific surface area of 0.9 to 14.2 m2/ g. X-ray diffraction analysis confirmed that the synthesis product, with the initial content of iron (III) nitrate nonahydrate from 70 to 90%, is Fe2O3. The highest specific surface area of the powder is observed at the initial ratio of components Fe(NO3)3 ∙ 9H2O (80%) + NH2CH2COOH (20%), which, taking into account moisture removal during drying, will correspond to Fe(NO3)3 ∙ 3H2O (75%) + NH2CH2COOH (25%). Based on this ratio of components, the possibility of controlling the size of powder particles by introducing an inert additive, aerosil grade A-380, into the composition was evaluated. It is shown that the introduction of 1.5% SiO2 into the composition leads to the formation of a mixture of Fe2O3 + Fe3O4 products, which makes it possible to achieve a specific surface area of 19.4 m2/g.