Papers by Keyword: Powder Property

Abstract: In order to lay raw materials foundation for increasing the performance of insulating brick with the low grade quartz sand along the Yangtze River, the effect of ball milling time on the properties of quartz sand powder was researched via the ball milling method in this paper. The results show the grain diameter of quartz sand powder is gradually decreased, the grain fineness distribution is tapered narrowing. The liquidity of quartz sand powders is became poor with an increaseding the ball milling rotate speed, howerver, the tendency of variation is gradually relaxative. The vibration compaction density is decreased with an increaseding the ball milling rotate speed, but the fall amplitude difference is gradually shrinked. The ball milling rotate speed for 250r/min is better through the whole cost performance analysis.

Abstract: The effects of the atomizing pressure on the microstructures and properties of the lead-free solder powder by the supersonic atomizer method were investigated. The microstructures of the brazed joint of solder paste were also observed. The results showed that with increasing atomizing pressures from 0.4 to 0.7 MPa, the powder particles are refined significantly and the effective atomization efficiency increases rapidly, but the oxygen content slightly rises. When the atomizing pressures increases from 0.7 to 0.9 MPa, the effective atomization efficiency only increases slightly, meanwhile both sphericity and roughness of the powder deteriorate. The atomized powder exhibits high effective atomizing efficiency, uniform size distribution, good sphericity and smooth surface when the atomizing pressure is 0.7 MPa. The diffusion layer brazed welded by Sn3Ag2.8Cu paste with Cu substrate is thicker and more irregular than that of by Sn37Pb paste.

Abstract: An investigation on the melt delivery tube tip pressure and the effective atomizing efficiency of atomizing powder was carried out. The results show that all of melt delivery tube tip pressures are negative value in the atomization gas pressure range of 0.4~0.9 MPa, and they monotonously increase with increasing the atomizing pressure; when the atomizing pressure is higher than 0.7 MPa, the negative pressure of the melt delivery tube tip is slowly increasing with continuously increasing the atomizing pressure; the atomized powder possesses higher effective atomizing efficiency, more uniform size distribution, better sphericity and smoother surface at the atomizing pressure of 0.7 MPa and the pressure of the melt delivery tube tip of -39.44 kPa.

Abstract: An update and the latest results on molten metal atomization using a Pressure-Gas- Atomizer will be given. This atomizer combines a swirl-pressure atomizer, to generate a liquid hollow cone film and a gas atomizer to atomize the film and/or the fragments of the film. The paper is focused on powder production, but this atomization system is also applicable for deposition purposes. Different alloys (Sn, SnCu) were atomized to study the characteristics of the Pressure- Gas-Atomizer. The powders produced were analyzed by laser diffraction and image processing. Among other parameters, the molten metal mass flow (~140 – 200 kg/h), the gas mass flow and the atomizer design were varied. The results include the effects of these variances on particle size and particle shape.

Abstract: Effects of powder properties of the filler, including the particle size, the specific surface area and the lattice strain on the dielectric permittivity and Q of the ceramics-polymer composites were investigated in order to achieve composites with high dielectric permittivity and Q. The dielectric properties of the composites were strongly influenced by the powder properties of the filler, despite that the fillers have the same composition. Generally, lower specific surface area and lower lattice strain of the filler lead to higher Q of the composites.

Abstract: We synthesized tricalcium phosphate (TCP) microspheres using an ultrasonic spray-pyrolysis technique, and investigated the effect of the concentrations of the starting solution on the powder properties. The XRD pattern showed that the crystalline phases of the resulting powders were β-TCP/HAp biphase in the case of pyrolysis temperature at 850 °C and TCP single phase at 1000 °C. The Ca/P molar ratios were determined by XRF to be at 1.50±0.03. The particle shapes of the powders were observed by SEM; the diameters of the microspheres were narrowly distributed from 0.5 to 4 µm. The mean particle diameters of the resulting powder increased with the concentration of the starting solutions and could be controlled in the range of 0.85-1.4 µm. When the compressed powder was sintered at 1050 °C for 5 h , the relative density of the sintered compact attained to 97%. The TCP microspheres had good sinterability.