Hongwu ZHANG
,
Zhao ZHANG
材料科学技术（英文）
Rate-dependent constitutive model was used to simulate the friction stir welding process. The effect of the viscosity coefficient and the process parameters on the material behaviors and the stress distributions around the pin were studied. Results indicate that the stress in front of the pin is larger than that behind the pin. The difference between the radial/circumferential stress in front of the pin and that behind it becomes smaller when the material gets closer to the top surface. This difference increases with increasing the viscosity coefficient and becomes smaller when the welding speed decreases. The variation of the angular velocity does not significantly affect the difference.
关键词:
Friction stir welding
,
stir
,
welding
,
Finite
,
element
,
met
Daming XU
,
Qingmei YU
,
Xin LI
,
Geying AN
材料科学技术（英文）
Recently proposed mathematical model for mold filling processes under centrifugal force field conditions and the computer codes were first tested through the sample simulation of gravity mold filling process for a benchmark plate-casting, which were compared with quoted experimental observations. The model and the developed computer program were then applied to the numerical simulation of centrifugal field mold filling processes for a thin-section casting with a titanium alloy melt of assumed viscosity of 1.2 and 12.0 mm2/s, respectively. The computation result comparison shows that the flow behaviors of the filling melts are basically similar to each other although the less viscous melt tends to fill into the thin section casting cavity faster.
关键词:
Centrifugal casting
,
null
,
null
,
null
何峰
,
平财明
,
郑媛媛
,
乔勇
硅酸盐通报
采用熔融冷却法制备了不同R’系数的高硼硅酸盐玻璃,其中R’=(Na2O-Al2O3)/B2O3.利用红外光谱、高温旋转粘度计和热膨胀仪等对玻璃的结构和性能进行表征.结果表明:高温段粘度-温度关系符合阿伦尼乌斯定律；R’值的增大导致非桥氧的增加,高温粘度和熔制温度呈显著降低.当R’＞0.5时,热膨胀系数近似线性增大,玻璃化转变温度增大至590℃基本维持不变.R’值影响结构中的[BO3]与[BO4]的比例及硅氧网络的完整程度,从而决定高硼硅酸盐玻璃的性能.
关键词:
高硼硅玻璃
,
R’值
,
粘度
,
热膨胀
新型炭材料
通过对吸附率(有效吸附系数)Ks和饱和吸附量msat的测量,描述了粘度为0.001 Pa·s～0.850 Pa·s的各种油类在膨胀石墨柱中的吸附动力学,发现吸附率Ks对油类粘度有很强的相关性.吸入膨胀石墨柱中的饱和吸附量msat几乎恒定在50kg/kg,该值略低于由膨胀石墨块直接浸渍在油中测得的吸附容量,这是由于所吸附的油沿膨胀石墨柱高度存在重力梯度.
关键词:
吸附
,
重油
,
煤油
,
膨胀石墨
,
动力学
,
粘度
刘鹏
,
王松
,
陈梦鹤
上海金属
Ficham和Richardson提出硅酸盐熔渣的结构包含3种不同的氧离子,即非桥氧、桥氧和自由氧,张国华又把氧离子细分为6种类型.基于张国华的模型,用6种不同类型的氧离子表示熔渣的结构,针对电渣重熔渣系高氟化钙的特点,重新对氟化钙的模型参数进行回归.利用修正后的模型,计算含TiO2的电渣重熔渣系黏度,计算结果和实验值符合较好.同时还从文献中查找了一些黏度数据,分别利用NPL模型、Riboud模型和修正后的模型进行计算,对比后发现修正后的模型能够很好地预测电渣重熔渣系黏度.
关键词:
电渣重熔
,
渣系
,
黏度
,
模型
