Sharif Digital Repository

In this work, the production and properties of Al 6061/SiC composites, made using a squeeze casting method, were investigated. SiC preforms were manufactured by mixing SiC powder, having a 16 and 22 pm particle size, with colloidal silica as a binder. 6061 Al melt was squeeze cast into the pores of the SiC preform to manufacture a DRA composite containing 30v/o reinforcement. The aging behavior, tensile properties and fracture mechanism of the cast material were studied. The results show that higher hardness, yield strength, tensile strength and Young's modulus can be obtained by the addition of SiC particles to 6061 Al alloy, whereas tensile elongation decreases. This is mainly caused by a... 

6061 aluminum matrix composites containing 30vol% SiC with mean mass particle size of 16 and 22 μm as the reinforcing phase were synthesized by squeeze casting route. The process consisted of fabricating of SiC preform followed by squeeze casting of 6061 aluminum alloy. The SiC preform was made by blending SiC particles with silica as a coal and sintering. The microstructural features, aging behavior, mechanical properties and wear characteristics of the composites were investigated. The results indicated that a homogenous distribution of SiC particles in the aluminum matrix, which is almost free of pores, can be obtained by squeeze casting method. Higher strength and lower wear rates were... 

In the present paper, an optimization of thermal barrier coating parameters is performed for diesel engine applications. The substrate is A356.0-T7, a cast aluminum alloy which has a vast application in diesel engines, and the alloy is coated by plasma sprayed ZrO2-8 wt.% Y2O3. Parameters including the feed rate of coating powders, the nozzle distance to specimen surfaces, and the coating thickness are optimized by thermal shock fatigue tests and bending tests. Optimum values of the feed rate and the nozzle distance are 30 g/min and 80 mm, respectively, when the objective is considered as maximizing the bending strength. Thermal shock tests demonstrate that lower thickness of coating layers... 

In the present paper, the heat treatment effect on A356.0, a cast aluminum alloy which has been widely used in diesel engine cylinder heads, is investigated under out-of-phase thermo-mechanical fatigue and low cycle fatigue (at different temperatures) loadings. A typical heat treatment is applied to the material including 8. h solution at 535 °C, water quench and 3. h ageing at 180 °C. The experimental fatigue results show that the heat treatment process has considerable influence on mechanical and low cycle fatigue behaviors, especially at room temperature, but its effect on thermo-mechanical fatigue lifetime is not significant. The improvement in the strength can be explained by the... 

In the present study, the out-of-phase thermomechanical fatigue (OP-TMF) behavior of a cast aluminum-silicon-magnesium alloy, the A356.0 alloy which has been widely used in diesel engine cylinder heads, is compared to room-temperature and high-temperature low cycle fatigue (RT-, HT-LCF) behaviors. For this purpose, strain/temperature-controlled isothermal and non-isothermal fatigue tests were performed based on realistic loading conditions in cylinder heads. Fatigue tests results showed that the plastic strain increased during cycles under constant mechanical strain amplitude, while the specimen failed. Under LCF loadings, the cyclic hardening occurred at low temperatures for the A356.0... 

The current study investigated the effect of heat treatment parameters, including solution treatment temperature (STT), time, and quench rate, on the microstructure, defects, and hardness of an Al-16Si-6Cu Shift fork die-cast alloy. The changes in primary silicon particle (PSP) features were examined quantitatively by optical microscopy, coupled with image analysis and SEM equipped with EDS. The biggest PSPs (27 ± 8 µm) and the highest area fraction (23%) were found in the sample solution treated at 470°C and cooled in the furnace. The hardness value increased in heat-treated samples slightly (140–148 BHN). A lower STT (420°C) and a lower ageing time (1 h) are suitable conditions for the...