Silica fume-formed during the manufacture of ferrosilicon alloys - as an extender pigment in anticorrosive paints

Purpose - This paper is concerned with the study of silica fume that arises in tonnage amounts during the manufacture of ferrosilicon alloys; this was done in order to maximize productivity and to create new market for industrial by-product and/or waste material. Design/methodology/approach - The structure and particle shape of silica fume were identified using X-ray diffraction and electron microscope, respectively. Standard methods were used for the identification of chemical analyses, solubility, hydrogen ion concentration, specific gravity, bulking value, oil absorption, chemical resistance and particle size. The characterized and evaluated silica fume was applied in several paint formulations. The physico-mechanical, chemical and corrosion protective properties of the paint films were measured according to standard methods. Findings - The silica fume under investigation was a fine lightweight fluffy amorphous powder. It has a grayish-white color that makes it suitable for use as a filler and extender pigment in a wide variety of different fields of application; its amorphous nature favors safe use from a standpoint of industrial hygiene. it can be used as an economic pigment that possesses suitable values of specific gravity, bulking value and oil absorption. It also is inert, neutral and of an excellent chemical resistance. The material can be used successfully as an extender pigment in different paint formulations; taking into consideration that alkyd resin based paints should not be used in alkaline environments or mixed with basic pigments, or the paint film will deteriorate. Silica fume particles in the pigment mixture may offer a suitable opportunity for the voids formed by the larger particles to be occupied by smaller ones to produce a condition of maximum packing. It can be successfully used with the flaky aluminum or stainless steel anticorrosive pigments to produce a highly efficient corrosion protective film, Originality/value - There is increasing environmental concern with regard to excessive volumes of solid waste hazards accumulation. Silica fume that arises - as a disposal material - in tonnage amounts during the manufacture of ferrosilicon alloys can find a new market in paint industry. It can be used successfully for anticorrosive paints to provide well backed paint films.