Z.S. Zhen
,
W.M. Mao
,
S.J. Yan
金属学报(英文版)
The Rheological behavior of semi-solid AZ91D at steady state is studied using a Couettetype viscometer in the present paper. The results show that the apparent viscosity ofsemi-solid AZ91D at the steady state increases with the solid fraction increasing, andgoes up sharply when the solid fraction reaches a certain value, which is called criticalfraction. In addition, the apparent viscosity of semi-solid AZ91D at the steady statetakes on a distinct downtrend with the shearing rate increasing, which indicates astrong shear thinning property. In addition, the critical solid fraction becomes higherunder larger shearing rate, owing to the more globular shape of the solid particles.Based on the present experiment results, an empirical equation is built as that, relatingthe steady state apparent viscosity of semi-solid AZ91D with the solid fraction fs andshearing rate γ at the same time: ηapp=10. 74exp(6.95fs)γ-0.86.
关键词:
Rheological behavior
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null
,
null
,
null
,
null
Weimin MAO
,
Zisheng ZHEN
,
Shijian YAN
,
Xueyou ZHONG
材料科学技术（英文）
The rheological behavior and microstructure of semi-solid AZ91D was studied using a Couette type viscometer. The results show that the apparent viscosity of semi-solid AZ91D increases with the cooling rate increasing when it is continuously cooled and mechanically stirred and the empiric relation of the apparent viscosity with the cooling rate and solid fraction at shearing rate 93.7 s-1 is expressed as η=[0.66-0.63e(-ε3.01)]e (fs/0.14), and with the shearing rate and solid fraction at cooling rate 4ºC/min is shown as η=0.55e(fs/0.11- /87.59), as well as the cooling rate and shearing rate have an important effect on the microstructure of the semi-solid AZ91D alloy slurry, and decreasing the cooling rate and increasing the shearing rate are favorable to the nondendritic evolution of the primary grains.
关键词:
Rheological behavior
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null
,
null
欧秋仁
,
嵇培军
,
肖军
,
赵亮
宇航材料工艺
doi:10.3969/j.issn.1007-2330.2015.04.018
采用流变仪、DSC、DMA、TGA和介电性能测试方法研究了用于RTM工艺的改性氰酸酯树脂的流变、固化反应特性、耐热性和介电性能.结果表明:改性氰酸酯树脂在90 ～ 170℃温度范围内黏度＜500 mPa·s,90℃时黏度为280mPa·s,适用期＞10 h;固化反应活化能为39.5 kJ/mol,反应级数为0.89;树脂固化后玻璃化转变温度为294℃,热分解温度为420c℃;9.375 GHz的介电常数为2.85,损耗角正切＜5×10-3.
关键词:
RTM
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氰酸酯树脂
,
流变特性
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玻璃化转变温度
,
介电性能
