Synthesizing and characterization of Cu-WC-Si composite prepared by using planetary ball milling
Cu-WC-Si composites were synthesized by using a planetary ball milling. Different composition of elemental Cu, WC and Ti powders were mixed and milled for 5 and 10 hours in an open air. The powder characterized before and after milling to expose the effect of milling variables on particle size, homogenization and contamination. Analyzing carried out by using X-ray and scanning electron microscope (SEM). The as milled particle size and homogenization generally influenced by milling time and tungsten Carbide (WC) content. With longer milling time and higher tungsten carbide content, particle size becomes smaller and smaller. The average particle sizes of the as milled powder are in ranged from 5µm to 30 µm and strongly depend on the copper content.
Characterization of nanocrystalline FeSiCr powders prepared by ball milling
Abstract FeSi 10 Cr 10 powder was mechanically alloyed by high energy planetary ball milling, starting from elemental powders. The microstructural and magnetic properties of the milled powders were characterized by scanning electron microscopy, X-ray diffraction, 57 Fe Mossbauer spectrometry and a vibratory sample magnetometer. After 3 h of milling, the formation of two bcc solid solutions α-Fe 1 (Si, Cr) and α-Fe 2 (Si, Cr) is observed. Their grain sizes decrease with increase in milling time attaining, at 15 h of milling, 23 and 11 nm, respectively. Mossbauer spectra of the milled powder show the presence of two components. One is a ferromagnetic type with a broad sextuplet. Its distribution of hyperfine field is characterized by high and low hyperfine field’s peaks and a mean value of 26.5 T. The other is a single paramagnetic peak. Its low concentration increases to ∼4% at 15 h of milling. These results can be explained by different atomic environments affected by Si or/and Cr elements, as well as the increased disordered grain boundaries. Magnetic measurements of the milled FeSi 10 Cr 10 alloy powder exhibit a soft ferromagnetic character with a decrease of both magnetization at saturation (Ms) and coercive force (Hc) with milling time attaining values of Ms=151 emu/g and Hc=2500 A/m at 30 h of milling time.
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.