Porous Powder Materials Research Articles

Porous powder materials for cleaning of fluids : L.P. Pililnevich et al. (PM Research Inst., Minsk, Belarus.)

Porous powder materials for cleaning of fluids : L.P. Pililnevich et al. (PM Research Inst., Minsk, Belarus.)

Densification model for porous metallic powder materials

A new mechanical model for powder metallurgy compaction is presented. In this model, various amount of voids can be introduced into a continuous solid, therefore the porosity can be conveniently controlled. The elastic–plastic finite element method was used to analyze the sintered powder material. The model was used to simulate compressing of a sintered cylinder. MSC.Marc of MSC.Software Corporation was applied here. Experiment was carried out using a computer controlled universal tensile testing machine. The load–displacement curves agree with the experimental results very well. The plastic deformation of a metallic material is mostly caused by the slipping of the crystal lattice. Although very small, a metal powder particle is composed of a metallic crystal. The mechanical properties of a powder particle should be very close to those of their solid metal counterpart.

Limit design of porous sintered metal powder machine elements

The modified plasticity theory for sintered powder materials, taking into account the real complex state of porosity and microdefects (cracks, non-metallic inclusions, etc.), proposed by the authors, was employed for calculating the limit loading conditions of elasto-plastically deformed porous powder sintered materials. The newly established yield function for porous materials is applied to simulate their consolidation taking also into account the current state of porosity at each stage of deformation. Such calculations are very useful for the limit design and manufacturing of engineering parts made of porous powder materials. The proposed theoretical model was experimentally validated in case studies related to axisymmetric metal powder machine elements, e.g., filters, loaded under various operating conditions.

Analysis of the gas permeability of porous powder materials

Equations for calculating the gas permeability of materials compacted from powders are given. Both viscous flow and sliding of gas molecules were taken into account. Calculated and experimental results agreed over a wide range of porosities. The equations are recommended for determining the permeability and specific surface area of compacted powder materials in engineering calculations.

Regularities of fracture processes in porous powder materials

We study distinctive features of the process of irreversible deformation of porous metallic materials, simulate the behavior of isolated contacts between particles of a powder under these conditions, and analyze the regularities of ductile fracture of powder materials on the basis of a micromechanical description of the behavior of contacts between particles.

Porous powder-fiber materials based on copper

A theoretical and experimental investigation of porous powder—fiber materials based on copper powder and fibers with a layered distribution of components was carried out. Maximum and average pore sizes, permeability coefficients, and efficiency parameters as functions of pressing pressure, powder particle size, and relative thickness of the fiber layer were investigated. It was shown that the use of components with certain dimensions permits the fabrication of materials with a high pore size gradient (up to 12 times) in a thickness of material that considerably increases the efficiency parameter E relative to that in porous powder and porous fiber materials.

Modeling the kinetics of infiltration of porous powder materials with melts

The infiltration of porous materials was analyzed using a three-dimensional model of the pore structure as a spatial lattice formed by monospherical particles. Coordination number, size, porosity, and interparticle contact area were taken into account. As examples, the kinetics of infiltration of poured titanium and steel powders, and also of sintered materials were calculated. Calculated and experimental results were found to be in satisfactory agreement.

Shrinkage kinetics in sintering laminated orthortropically porous powder materials

Technological developments in recent years have created suitable conditions for producing the so-called anisotropically porous powder materials. Their anisotropy forms as a result of directional distribution of pores having the form d continuous capillaries (channels) which penetrate through the porous matrix in the given directions. These materials are biporous: anisotropic porosity, formed by channels, is combined in them with the isotropic porosity of interchannel walls formed by powder particles from which the matrix is produced.

Electron microscopy study of shock synthesis of silicides

Shock-induced reactions (or shock synthesis) have been studied since the 1960’s but are still poorly understood, partly due to the fact that the reaction kinetics are very fast making experimental analysis of the reaction difficult. Shock synthesis is closely related to combustion synthesis, and occurs in the same systems that undergo exothermic gasless combustion reactions. The thermite reaction (Fe2O3 + 2Al -> 2Fe + Al2O3) is prototypical of this class of reactions. The effects of shock-wave passage through porous (powder) materials are complex, because intense and non-uniform plastic deformation is coupled with the shock-wave effects. Thus, the particle interiors experience primarily the effects of shock waves, while the surfaces undergo intense plastic deformation which can often result in interfacial melting. Shock synthesis of compounds from powders is triggered by the extraordinarily high energy deposition rate at the surfaces of the powders, forcing them in close contact, activating them by introducing defects, and heating them close to or even above their melting temperatures.

Aspects of the formation of porous powder materials with variable pore distribution in a pseudofluidized bed

Aspects of the formation of porous powder materials with variable pore distribution in a pseudofluidized bed

Efficiency of capillary porous powder materials

Efficiency of capillary porous powder materials

Statistical description of particle correlations in porous media

A simple algorithm for calculating the two-particle distribution function for realistic porous media on the basis of experimental data is presented. The method is proven by considering various porous powder materials.

Influence of the structural properties of porous powder materials on the uniformity of local permeability

Influence of the structural properties of porous powder materials on the uniformity of local permeability

Properties of porous powder materials

Properties of porous powder materials

A method of measurement of the local permeability of porous powder materials with the use of a hot-wire anemometer

A method of measurement of the local permeability of porous powder materials with the use of a hot-wire anemometer

Investigation of pore size distribution in porous powder materials by different methods

Investigation of pore size distribution in porous powder materials by different methods

The physicomechanical properties of porous titanium base powder materials

The physicomechanical properties of porous titanium base powder materials

Anisotropy of the properties of porous powder materials in uniaxial compression

Anisotropy of the properties of porous powder materials in uniaxial compression

The hydraulic characteristics of titanium-base porous powder materials

The hydraulic characteristics of titanium-base porous powder materials

Porous powder materials with lyophilic additions

Porous powder materials with lyophilic additions