White Soot Research Articles

Technology of phosphorus slag processing for preparation of precipitated silica

The article presents the results of studying the determination of the influence of the nature of a number of mineral reagents (solutions of hydrochloric, nitric, sulfur and phosphoric acids, as well as sodium hydroxide and carbonate) on silicon extraction in solution upon he leaching of phosphorus production slags. The results of studying the process of the breakdown of phosphorus production slag with sodium carbonate solutions depending on various physicochemical parameters are provided. The optimum conditions of main technological operations were found and the main parameters that influence the morphological structure and size of precipitated silica particles were established. The influence of the conditions of washing of carbonate-silicate cake on its chemical, phase, and granulometric composition has been studied. Scaled-up laboratory tests have been carried out and a technology for processing phosphorus production slags to produce mineral fillers was developed on their basis. Conclusions on the applicability of pilot batches of white soot in tire and paint industries and carbonate-silicate fillers in construction industry and agriculture were obtained.

Evaluation of the magnesium and silicon diffusion rates in forsterite synthesis using various magnesium compounds

In forsterite synthesis from highly disperse SiO2 (white soot or silica sol) and magnesium chloride, nitrate, sulfate, acetate, or citrate through sol-gel processing, with polyvinyl alcohol as a gel former, the reaction products are forsterite, magnesium oxide, silica, and clinoenstatite. From analysis of the synthesis products, we assess the relationship between the diffusion rates of the magnesium and silicon cations. Phase-pure forsterite can be obtained by reacting white soot and magnesium acetate.

Physicochemical properties of amorphous silicon dioxide produced from nepheline

The properties of silicon dioxide precipitates produced by acid processing of nepheline have been investigated. Regardless of the production method, silicon dioxide takes an intermediate position between commercial silica gel and white soot in terms of the structure and some physicochemical properties, this position determining possible applications of this product.

Polymerization of butadiene by neodymium catalysts on oxide supports

The suspension polymerization of butadiene in hexane and toluene in the presence of catalysts composed of organoaluminum compounds and neodymium versatate applied on oxides (Al2O3, aluminum silicate A-14, Aerosil A-300, and white soot BS-200) has been studied. Triisobutylaluminum and its combination with ethylaluminum sesquichloride are used as organoaluminum compounds. The activity and stereospecificity of the catalysts has been found to depend strongly on the nature of supports. Catalysts based on Aerosil and white soot appear to be the most active. With the use of these catalysts, polybutadiene containing up to 97.5% 1,4-cis-units has been synthesized.

(NH4)2SiF6 evaporation in the presence of SiO2

The kinetics and mechanism of the solid-phase reaction between (NH4)2SiF6 and silica at molar ratios of (0.5–5): 1 were studied. SiO2 is bound with (NH4)2SiF6 to form volatile NH4SiOF3, which abruptly enhances the ammonium hexafluorosilicate evaporation. The activation energy and rate constants of evaporation were calculated for an (NH4)2SiF6 + SiO2 (2: 1) mixture in the range 220–300°C. The reaction with crystalline SiO2 has a higher yield than with an amorphous “white soot.” The role of the SiO2 surface in the formation of the volatile products is discussed. The phase and chemical composition of the sublimates was studied.

Structure And Stress Evaluation Of Diamond Films Deposited On Ti-6A1-4V Alloy At Low Temperature Using Ch4/O2/H2 And CO/H2 Gas Mixtures

ABSTRACTLow temperature diamond deposition on metal substrates is motivated by the need to reduce thermal stress so that the film adhesion is satisfactory. Although the use of oxygen-con- taining gas mixtures have been shown to extend the temperature range for which diamond can grow as well as to improve film quality, most studies have focused on the use of silicon as sub- strates and have neglected technologically important metallic systems. To this end, microwave plasma chemical vapor deposition (MPCVD) was used to grow diamond films on Ti-6A1-4V alloy at low temperature (615 to 780 C) using CH4/O2/H2 and CO/H2 gas mixtures. In-situ pyrometric interferometry (ISPI) shows that as the oxygen concentration increases, the onset time for dia- mond nucleation and subsequent film surface roughness increases while the average growth rate decreases. Micro-Raman spectroscopy shows improved film quality and suggests a trend toward increasing in-plane compressive stress with increasing oxygen concentration. Glancing-angle x- ray diffraction (XRD) was complimentary to the Raman data and indicates the presence of a TiC interfacial layer thickness which decreases with increasing oxygen concentration. We found that the CO/H2 mixture resulted in poorly adhered “white soot” films with low diamond content whereas the CH4/O2/H2 mixture yielded well adhered high quality diamond films.

An investigation of the thermal diffusivity and thermal conductivity of insulating powders at atmospheric pressure and in vacuum by various methods

This paper gives the results of measurements of the thermal diffusivity and thermal conductivity of an aerogel, perlite powder, and white soot by the steady-state method, the continuous heating method, and the method of the regular regime of the first kind. The experimental data agree well with theory.