Structural and hydraulic characteristics of porous materials made of VT6 titanium alloy fibers

Capillary Flow Porometry to Assess the Seal Provided by Root-End Filling Materials in a Standardized and Reproducible Way

Laser melting and re‐solidification has been used to densify and homogenize ceramic surfaces, leading to increased high‐temperature corrosion and erosion resistance. Although complete sealing of pores can be achieved on the surface, pores have been observed in the boundary between the laser‐treated zone and the untreated bulk. This paper investigates the mechanisms of pore formation and the various factors affecting it. A simple analytical model that predicts the maximum final pore diameter and location along the treated zone/untreated bulk boundary is derived, in terms of the materials properties and the processing parameters. Experimental investigations for a range of processing speeds and power densities have verified the model predictions, identifying the effects of processing speed and laser power density on the maximum pore diameter.

Porosity of electrospun web could be evaluated by the diameter of the maximum pore and the reliability of this value. The distributions of the maximum pore diameter usually differ from Gausian normal distribution, and due to that the standard reliability cannot be used for maximum pore size prediction. The method of electrospun web porosity evaluation by the maximum pore size in the Web is presented in this paper. The main investigations were done with polyamide 6 electrospun nanofibrous web. It was stated that in order to estimate the maximum pore size with a confidence level of 99.5%, it is not possible to use the standard 3S (3 standard deviations) rule in all cases. For reliability prediction, it is possible to use skewness coefficient A or a relative distance between the maximum pore diameter and average value Δd. When skewness coefficient A is up to 1.5 or Δd up to 120% the 4S rule needs to be used instead 3S rule for the same 99.5% reliability prediction.

Biocompatible, highly interconnected microporous poly(L-lactic acid) (PLLA) foams or scaffolds with nano-fibrous structure, containing pores with diameters of 0.1–3.5 μm and fibers with diameters of 300–700 nm scale, were prepared through the thermally induced liquid–liquid phase separation (TIPS) method using N,N′-dimethyl acetamide (DMAc) as solvent. Various foam morphologies were obtained by changing parameters involved in the TIPS process, such as polymer concentration, solvent composition, and quenching temperatures. The morphology of different foams was examined by scanning electron microscopy, whereas the pore size and the pore size distribution were calculated. The results showed that most porous foams presented nano-fibrous structure with interconnected open pores. In the case of using DMAc as solvent, with increasing polymer concentration, either the average pore diameter or the pore size distribution exhibited a maximum value at 0.05 g/mL polymer concentration and quenching temperature of −30°C. It was found that all the pore size distribution fit the F-distribution equation. With increasing the quenching temperature from −30°C to −10°C, the maximum average pore diameter of the foams decreased and the pore size distribution became narrower, whereas the polymer concentration exhibiting the maximum pore size and widest pore size distribution increased from 0.05 g/mL to 0.07 g/mL. In the case of using the mixed solvent of DMAc/DOX (1,4-dioxane) from 9/1 to 7/3 (v/v) there appeared a maximum value of average pore diameter and a widest pore size distribution all at 0.05 g/mL PLLA concentration and quenching temperature of −30°C. The maximum pore size tends to increase with increasing DOX content.

We investigated the effect of different sintering temperatures ranging from 200 to 600 on the porous properties and pore microstructure of large capillary pressure wicks made of carbonyl nickel powder. The evolution model of hydraulic diameter was established and verified by the maximum pore diameter. Hydraulic diameter changed as the roughness of particle surfaces decreased and sintering necks grew large during sintering. In the contact-formation stage and the initial sintering stage (200–500), the decrease in the roughness of particle surfaces played a decisive role, contributing to an increase in hydraulic diameter. In the intermediate sintering stage (600), the growth of sintering necks dominated the process, however the hydraulic diameter was reduced. These results show that the maximum pore diameter first increased and then decreased in the same way as our evolution model. Permeability and capillary performance of the wicks first increased and then declined with increasing sintering temperature. We found the optimal sintering temperature to be 400, at which point the wicks achieved the maximum pore diameter of 1.21 μm, a permeability of 1.77 × 10−14 m2, and their highest capillary performance of 1.46 × 10−8 m.

A 3D point cloud and deep learning based automated process for quantifying multi-scale phenotypes in sliced bread.

Investigation of membrane wetting for CO2 capture by gas–liquid contactor based on ceramic membrane

Microleakage of Accelerated Mineral Trioxide Aggregate and Portland Cement in an In Vitro Apexification Model

Neck-size distributions of through-pores in polymer membranes

Structural characteristics of catalytic systems obtained by modification of activated carbon with Al and Ni metal oxides have been studied. Modification of activated carbon was carried out by impregnating them with metal hydroxides from salt solutions with a Ni+2/Al+3 ratio of 2:1 and 3:1, followed by calcination in a stream of nitrogen and hydrogen until oxide phaseswere formed. With an increase in the ratio of metal cations in the impregnating solution in activated carbon, the specific surface area and the number of micropores increase, and the total volume and average pore diameter. Ignition in a hydrogen flowat the final stage of activated carbon modification leads to a decrease in the pore space and a decrease in the specific surface area of the catalytic system. The optimal combination of specific surface values and maximum average pore diameters for the processing of heavy oil residue have Ni/Al (2:1) catalytic systems obtained in nitrogen and hydrogen.

Purpose. Development analytical model of the liner, taking into account its previous tension, structural and technological parameters and physical-mechanical characteristics of the rubber material, for modeling its deformations in the radial, longitudinal and circular planes. Methods. Analytical, mathematical modeling. Results. On the basis of the equilibrium equations for a cylindrical shell, taking into account the isotropy of the medium and the without momentary stress state, the spatial of forces and the preliminary tension of the liner, a system of analytic equations is developed that enables modelling of the deformations of the liner, which is the factor of its closure. The analytical dependences of the deformation of the liner in the longitudinal, circular and radial planes, depending on its structural parameters and physical and mechanical characteristics of the material, are developed. Parameters for deformation simulation are: R – radius of liner, Е – modulus of elasticity, h – thickness of liner, рн – vacuum pressure, l – the length of the active part of liner, ν – Poisson's coefficient for rubber, Fн force of tension of liner. Depending on the central angle in the radial plane of the section, the shape of the deformation of the liner is simulated along its entire working length. Conclusions. The obtained dependences allow simulating the deformation of the liner in the longitudinal, circular and radial planes, depending on its structural parameters and physical-mechanical characteristics of the material. The developed analytical dependences take into account the preliminary tension of the liner, the vacuum pressure and makes it possible to model, depending on the central angle in the radial plane of the cross-section of rubber. The use of developed analytical dependencies makes it possible to substantiate the basic parameters that influence the technological process of milk yield cows Keywords: liner, vacuum pressure, modulus of elasticity, radial deformation, coordinate system, tension of rubber, the cylindrical shell, the isotropic medium.

Pore evolution in extrusion-based 3D printed cementitious materials due to calcium leaching

Influence of initial powders morphology on structural-dimensional characteristics of porous ceramic materials based on SiC/MgO–SiO2

Effect of uni-axial loading on the nanostructure of silica aerogels

Strong impact does serious harm to the military industries so it is necessary to choose reasonable cushioning material and design effective buffers to prevent the impact of equipment. Based on the capillary property entangled porous metallic wire materials (EPMWM), this paper designed a composite buffer which uses EPMWM and viscous fluid as cushioning materials under the low-speed impact of the recoil force device of weapon equipment (such as artillery, mortar, etc.). Combined with the capillary model, porosity, hydraulic diameter, maximum pore diameter and pore distribution were used to characterize the pore structure characteristics of EPMWM. The calculation model of the damping force of the composite buffer was established. The low-speed impact test of the composite buffer was conducted. The parameters of the buffer under low-speed impact were identified according to the model, and the nonlinear model of damping force was obtained. The test results show that the composite buffer with EPMWM and viscous fluid can absorb the impact energy from the recoil movement effectively, and provide a new method for the buffer design of weapon equipment (such as artillery, mortar, etc.).