Determination of Relation between Elastic Constant and Si ntered Temperature in WC-Ni Composites
In this study we have investigated relation between elasti c constant and sintered temperature in tungsten carbide- nickel composite samples. Determination of elastic properties of materials is based on the transverse and longitudinal wave’s velocities via ultrasonic methods. In this study ultrasonic velocity measurements were measured in the WC-Ni composites. These samples are formed by powder metallurgy and electroless plating. Samples were sintered at temperat ures of 1000 °C, 1100 °C, 1200 °C and 1300 °C with Ar gas atmosphere in tube furnace. In the measuring ultrasonic longitudinal velocity 2 and 5 MHz transducers, ultrasonic transverse velocity 1 and 5MHz transducers have been used. Young Modulus (E) has been calculated by using longitudinal and transverse velocity. A fter we calculated elastic constant, we have investigated relation between sinter ed temperature and elastic constant of samples. A linear relation between sinter ed temperature and elastic constant in samples is observed.
Constants of elasticity of Li2O–B2O3–fly ash: Structural study by ultrasonic technique
Abstract Fly ash obtained from Toshkey project, which in turn was delivered from France, is a valuable source of many oxides such as SiO 2 , Al 2 O 3 , Fe 2 O 3 , CaO and MgO. These oxides can provide a useful preliminary source for the glass formation. Glass of the system 10Li 2 O–90B 2 O 3 (wt.%) has been prepared. The progressive addition of fly ash to this type of glass was made to study its effect on the chemical and physical properties of the parent glass. Room temperature ultrasonic measurements were performed by pulse-echo method. The density of the prepared samples was measured to justify the packing arrangements of the constituent oxides. The variations in the density and the ultrasonic velocity of the prepared samples containing progressive fly ash content were correlated and discussed. The values of elastic moduli (Young's modulus, bulk modulus and shear modulus) and Poisson's ratio were compared with those theoretically calculated in terms of Makishima–Mackenzie model and a model proposed by Rocherulle et al. [J. Rocherulle, C. Ecolivet, M. Poulain, P. Verdier, Y. Laurent, J. Non-Cryst. Solids 108 (1989) 187].
Experimental investigation of the geotechnical properties and microstructure of lime-stabilized saline soils under freeze-thaw cycling
Abstract The Song-Nen Plain in northeastern China holds one of the three largest expanses of soda saline-alkali soil in the world. Due to its disadvantageous geotechnical properties, the saline soil in this area is unable to meet the needs of construction projects. This study evaluates the stabilizing effect of adding lime to such soils. Specifically, it investigates how the physicochemical and mechanical properties and microstructure of soda saline-alkali soil are altered by lime and how these changes are affected by both freeze-thaw cycling and the duration of curing. The results reveal that adding lime to saline soil transforms clay particles into sand and silt particles and causes the pore size distribution (PSD) to become bimodal, with small-pore and macropore populations. An increase in lime content leads to an increase in the unconfined compressive strength (UCS) but a gradual decrease in both the cation exchange capacity (CEC) and plastic index. Freeze-thaw cycles break up coarse particles and aggregate finer particles, increasing the diameter of macropores and decreasing the USC; however, the effect on specimens with >9% lime is negligible. It is further shown that the geotechnical properties of the soil change immediately after the addition of lime, indicating that the cation exchange reaction takes place very quickly. Furthermore, the pozzolanic reaction leads to an increase in the percentage of sand-sized particles and a decrease in porosity after 28 days of curing. Overall, these results indicate that it is feasible to use lime to improve the engineering properties of soda saline-alkali soil in this area.