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报道了一种新颖、高效的采用气冷搅拌杆制备半固态浆料的工艺,该工艺通过将压缩空气不断注入到搅拌杆内腔来冷却熔体。采用该工艺制备了一种新近研发的高导热Al-8Si合金半固态浆料,并将该工艺与高压铸造机结合生产出一种无线基站用薄壁散热壳体件。研究了气体流量对初生晶粒的形貌、流变压铸件的力学性能及导热系数的影响。结果表明:当气体流量超过3 L/s时,采用该工艺可以制备出优质的半固态浆料。当气体流量为5 L/s时,流变压铸件的力学性能和导热系数最高,分别为抗拉强度261 MPa,屈服强度124 MPa,伸长率4.9%,显微硬度HV 99和导热系数153 W/(m·K)。相比于传统压铸件,采用气冷搅拌杆流变压铸工艺生产的铸件力学性能和伸长率大大提高,其抗拉强度、屈服强度、伸长率、显微硬度和导热系数的增长率分别为20%、15%、88%、13%和10%。
Reported a novel and efficient process for the preparation of semi-solid slurries using air-cooled stirring rods that cool the melt by continuously injecting compressed air into the mixing rod lumens. A newly developed high thermal conductivity Al-8Si alloy semi-solid slurry was prepared by this process. The process was combined with high-pressure casting machine to produce a thin-walled heat-radiating shell member for wireless base station. The effects of gas flow on the morphology of primary grains, the mechanical properties and the thermal conductivity of rheo-diecasting die were investigated. The results show that when the gas flow rate exceeds 3 L / s, the process can be used to prepare high quality semisolid slurry. When gas flow rate is 5 L / s, the mechanical properties and thermal conductivity of rheo-diecasting are the highest, which are 261 MPa, yield strength 124 MPa, elongation 4.9%, microhardness HV 99 and thermal conductivity 153 W / (m · K). Compared with the traditional die-castings, the mechanical properties and elongation of castings produced by the rheological die-casting process with air-cooled mixing rod are greatly improved. The growth rates of tensile strength, yield strength, elongation, microhardness and thermal conductivity are 20%, 15%, 88%, 13% and 10%.