One of the operational parameters in ball mill grinding process of composite cement is clinker hardness (litre weight of clinker). The quantity of fly ash to be blended in the composite cement is highly dependent on the clinker hardness. In this paper, the Response Surface Methodology (RSM) is used to formulate the experimental design and to analyze the effect of the operational parameters (input factors) such as clinker feed rate in tonnes per hour, fly ash feed rate in tonnes per hour and litre weight of clinker (clinker hardness) in grams/litre. The responses reported were mill output in tonnes per hour, cement residue in percentage, three days compressive strength in kg cm(-2), 28 days compressive strength in kg cm(-2), initial setting time and final setting time in minutes. The analysis using RSM revealed that in general the clinker hardness significantly affected the mill output. Mathematical models were developed to predict the responses.
This paper reports the response of microstructure and mechanical properties of a near-beta Ti-4Al-1Sn-2Zr-5Mo-8V-2.5Cr (wt.%) alloy after thermomechanical processing. Microstructure observation shows that the precipitation of the primary a phase depends on solution temperature. The highest volume fraction and the smallest size of the secondary a phase precipitated after solution treatment near the phase transition point plus aged treatment at 480 degrees C. Schematic illustration of the microstructure evolution after different heat treatments was described. Compared with the alloy after solution treatment at beta phase region, the alloy has higher ultimate tensile strength after solution treatment at alpha/beta phase region owing to the alloy precipitates primary alpha phase. It was found that the alloy after solution treatment at 720 degrees C plus aging treatment at 440 degrees C has a better ultimate tensile strength of about 1611 MPa, the elongation of about 2.53 %. The main reason is that the precipitation of the secondary alpha phase contributed to tensile properties substantially.
Magnesium biocompatibility and mechanical properties comparable with those of bones predetermine magnesium and materials based on magnesium for application as biodegradable implants. Pure magnesium usually has very poor properties that need to be improved. These properties can be improved by various alloying elements. However, these elements are usually not biocompatible. An alternative way to improve both mechanical and corrosion properties is by using composite materials. The presence of hydroxyapatite in magnesium should improve the mechanical properties and, at the same time, reduce the rate of corrosion by the barrier effect. This paper focuses on Mg/HA composite materials prepared from pure magnesium powders and hydroxyapatite (HA) powders. Powders were consolidated via cold compaction and subsequently directly extruded. The microstructure was revealed through SEM-EDS, mechanical properties were determined by tensile test. The corrosion resistance of composites was evaluated by immersion and electrochemical measurements in simulated body fluid.
In the present study, the tensile creep behaviour of three various cladding tubes of the Zr1%Nb alloy has been studied in the alpha-Zr region at 350 degrees C, which corresponds to the operational service conditions of the cladding tubes in nuclear light-water reactors. Tensile creep tests under the high constant applied stress region from 150 to 260 MPa have been carried out at the transition from the power-law (PL) to the power-law breakdown (PLB) regimes. It was found that all dispersion strengthened Zr1%Nb cladding alloys under investigation reach the PLB regime at values of the compensated applied stress sigma/G above approximately 8 x 10-3, where the stress exponent n of the minimum creep rate epsilon m (n = ( partial differential ln epsilon m/ partial differential ln sigma)T) then dramatically increases from the value of similar to 6 with increasing stress ratio sigma/G. The fact that all experimental results for both the PL and PLB obey the Monkman-Grant relationship supports the idea that the creep mechanism in the PL and PLB does not change qualitatively and indicates a close link between the deformation and fracture processes in both creep regimes under investigation. However, future experiments could be carried out at different testing temperatures within the PLB regime to verify the controversial contemporary views.
The mechanics of a solid body is based on Hooke's law.The non-linearity of the stress-strain curve in cyclic loading begins at much lower stress values than at the static yield stress point.A sensitive measurement of hysteresis loops led to discovering the anelastic strain processes below the yield stress and also below the fatigue limit.In this paper, the anelasticity limit is defined -the limit between reversible and irreversible strains -which is in compliance with the fatigue damage cumulation.
