Spectrographic determination of impurities in ultrapure tungsten and tungsten oxide.
The effects of an external magnetic field and of the diameter of the anode on the spectroscopic line intensity of the impurity elements in ultrapure tungsten and tungsten oxide have been studied. The results obtained are used for the development of a more sensitive method for the determination of these impurities (Mn, Pb, Fe, Ni, Al, Mo, V, Cu, Cr).
Electrothermal AAS determination of bismuth, antimony and tin in high-purity WO3
SummaryFour methods for the bulk trace determination of Bi, Sb and Sn in WO3 were developed and tested. In all cases, the final determination is carried out by graphite furnace atomic absorption spectrophotometry. The limits of detection range from 1 μg/g for a very fast and simple method to 50 ng/g for a method comprising a trace-matrix separation by sorption and complexation on activated carbon powder loaded with TMDTC. A way of preparation of standard reference WO3-samples doped with varying amounts of Bi, Sb and Sn traces is also described.
Mathematical Simulation of Combustion of Boron Powder Gas Suspension
Based on a two-phase two-velocity model of a reacting gas-dispersed medium, a mathematical model of combustion of a boron powder gas suspension has been formulated. The results of numerical solution of the problem are presented. The influence of the composition of the gas suspension, its size, size distribution of particles, mass concentration of particles, as well as of the presence of aluminum powder in the suspension on the visible and normal velocities of flame propagation in the gas suspension, is shown. A comparison of the results of calculation with the well-known experimental and theoretical data is carried out. Satisfactory agreement of the predicted results with experimental data is shown.