In this research, the effects of the powder particle size on the compaction and sintering of Hydride– Dehydride titanium powders are investigated. Commercially pure titanium powders with three different size ranges were utilized. Compaction was accomplished under applied pressures of 200 to 650 MPa. Sintering was carried out at 1100 to 1400 º C temperatures. The Compressibility behavior of the differently-sized powders was studied by measuring the density of the green compacts. The microstructure of the produced compacts was studied using scanning electron microscopy. Results showed that the small powders have the least Compressibility. The Compressibility data was analyzed and studied by common compaction equations. The modified Heckel equation showed the best correspondence. In addition, measuring the density of the sintered compacts showed that the small powders had the highest sinterability. The highest amount of sintered density (98% theoretical) was attained for the small powders compacted under 650 MPa and sintered at 1400 º C. However, the sintering temperature of 1200 º C was recognized as the most appropriate temperature for the middle and large-sized titanium powders. The results of the hardness tests showed that the appropriate mechanical properties could be attained for commercially pure titanium powder compacts by vacuum sintering accomplished at the optimum sintering circumstances.

1. Introduction: Cement treatment produces bonding strength between soils particles that makes their behavior different from the behavior of reconstructed soils without structure. Soft cemented soils show a great change in their void ratio after virgin yielding as the result of destruction of their cemented structure. In this paper the Compressibility of soft cemented soils was investigated in the laboratory. In order to obtain highly compressible cemented soil specimens, an artificially soil was produced mixing clay, silt and sand with cement and polystyrene granules with water content more than liquid limit. …

Determination of porosity, permeability, and pore volume Compressibility of reservoir rocks and those variations with effective stress changes are of great interest in petroleum engineering. This paper has studied the influence of pore types of carbonate reservoir rocks on pore volume Compressibility as well as Klinkenberg permeability and porosity at different stress values. In the current study pore volume Compressibility tests have been done on 38 limestone and 8 dolomite samples. The experiments show the importance of rock type description of the reservoir rocks. Carbonate rocks with touching vug pores have different behavior from the other studied carbonates in this paper. This complex behavior is related to the role of connecting paths closure on the characteristics of hydraulic conductivity of the rock while there is no more changes in porosity or volume change. It means that the planar connecting paths have more effect on hydraulic conductivity of this rock type, while it has not more effect on porosity. Also, in all rock types excluding touching vuggy pores limestone, increasing the initial porosity leads to increase the permeability at the same effective stress value.

By means of numerical techniques, the effect of lubricant Compressibility on hydrodynamic behavior of heavily loaded journal bearings is studied in the present work. To reach this goal, the set of continuity and momentum equations for compressible two-dimensional lubricant flow in journal bearings are solved numerically by CFD method. The journal bearing under consideration has infinite length and the lubricant flow is assumed to be laminar and isoviscous. Although the lubricant is liquid, in the cases of high bearing loads, the variation of density with pressure may be important. Therefore, in the computations, the lubricant density is considered variable as a function of pressure. Considering the complex geometry in the physical domain, an attempt is made to transfer the set of governing equations into computational plane by means of conformal mapping. The transformed forms of equations are discretized by the control volume method and are solved using the SIMPLE Algorithm. Results show that the Compressibility effect causes an increase in the generated hydrodynamic pressure, such that this effect is enhanced under the condition of high shaft rotational speed, small clearance and high eccentricity ratio.