Filtering properties of highly porous materials prepared from iron powders with nonspherical particles

Conclusions We have shown that the method for preparing the initial powder has an effect on the permeability of the porous material.Other conditions being equal, the permeability is somewhat lower in specimens prepared from reduced powder than with fluidized and spherical powder. However, the possibility of using reduced powder to make components with a higher porosity and hence with a higher permeability makes use of this powder desirable.An increase in porosity of the material from 30 to 55% leads to an increase in permeability from 0.6 to 11.0 liter/min·cm² for a pressure drop of 0.3 kg/cm².A change in thickness of the specimen from 0.5 to 3 mm reduces the permeability by a factor of 2.5–6, and a change in the particle size from 60 to 110 increases the permeability by more than 1.3- to 1.6-fold.A comparison of filters with the same degree of purification, made from spherical and nonspherical powders, shows that they have approximately the same transmission capacity.The data obtained for the filtering capacity of a porous material as a function of the particle size of the powder, the wall thickness, and pressure drop can serve as a basis for selecting the characteristics of a material as a function of the actual design requirements.     

Producing thin sheet materials of copper-tin powders

Conclusions A study was carried out on rolling powders of copper with 6.5% tin, sintering, compression rolling, and thermal stabilization of the strip. The thin strip of tin bronze is used as tools for cutting diamond crystals.Translated from Poroshkovaya Metallurgiya, No. 6 (66),pp. 95–97, June, 1968.     

粉末粒径对Cu-Al多孔材料孔结构的影响

在元素粉末反应制备多孔材料中,原料粉末粒度是影响其多孔结构的主要因素之一。本文通过元素粉末反应合成的方法制备Cu-Al多孔材料,研究原料粉末的粒径对Cu-Al多孔材料孔径、孔隙度、透气度和体积膨胀率等参数的影响。结果表明:Al粉粒径是影响Cu-Al多孔材料最大孔径的主要因素,材料的最大孔径dm与Al粉粒径dp之间严格遵循dm=0.48dp的线性变化规律;Cu粉粒径则对Cu-Al多孔材料最大孔径影响较小。当粉末粒径在48.5μm以上时,粉末粒径的改变对Cu-Al多孔材料的开孔隙度和总孔隙度影响不大。在实验研究范围内,Cu-Al多孔材料的体积膨胀率随粉末粒径的增大而增大;当粉末粒径很小时,Cu-Al多孔材料存在体积收缩的趋势。     

Production of tungsten-based composite materials from mechanically activated powders

The effects of the composition and metal additives on the compressibility of mechanically activated tungsten-based powder mixtures, the volume changes upon sintering, and the structure and strength of high-temperature composite materials are studied.     

Effect of grain size and concentration of diamond powders on compacting and properties of metal-diamond materials

Nizhegorod Polytechnic. Translated from Poroshkovaya Metallurgiya, No. 5, pp. 26–28, May, 1993.     

Ordered mesoporous polymers of tunable pore size from colloidal silica templates

Ordered mesoporous polymers have been prepared by replication of colloidal crystals made from silica spheres 35 nanometers in diameter. The pores in the colloidal crystals were filled with divinylbenzene (DVB), ethyleneglycol dimethacrylate (EDMA), or a mixture of the two. Polymerization and subsequent dissolution of the silica template leaves a polycrystalline network of interconnected pores. When mixtures of DVB and EDMA are used, the pore size of the polymer replicas can be varied continuously between 35 and 15 nanometers because the polymer shrinks when the silica template is removed.     

Production and properties of metal-PTFE antifriction materials from atomized bronze powders

Conclusions An investigation into the sinterability of loosely poured atomized bronze powders has established that the porosity of resultant sintered bronze skeletons depends on the particle size and shape. The shape of the bronze powder particles has some effect on the antifriction characteristics of a metal -PTFE material, but its coefficient of friction and wear resistance are affected more strongly by the composition of a solid lubricant introduced into the pores of its sintered skeleton. Using a nonspherical rather than spherical bronze powder gives a bronze saving of 15–20% without affecting the good antifriction properties of metal-PTFE materials, by increasing the porosity of their skeletons. Replacing molybdenum disulfide with graphite substantially increases the wear resistance of two-layer metal-PTFE materials and markedly decreases their cost, since the price of molybdenum disulfide is more than 20 times that of graphite.Translated from Poroshkovaya Metallurgiya, No. 9(273), pp. 30–34, September, 1985.