M.Szubryt
,
J.Brózda
金属学报(英文版)
The influence of welding parameters of butt joints, made by three processes (MMA, MAGand T.I.M.E), on their geometric characteristics has been evaluated, which in turn caused a change of the fatigue strength. That fore the statistic analysis and FEM were used and a method developed in the Institute of Welding, which consist in a direct connection of parameters used during welding with the fatigue strength of joints welded by various processes. It has been proven, among others.which by using more advanced welding processes (TLM.E) the fatigue strength of welded joints can be increased in comparison to joints welded by MMA and MAG.
关键词:
fatigue strength
,
null
,
null
Physical Review B
The Hamiltonian for a four-sublattice Heisenberg ferrimagnet or ferromagnet with different exchange constants (J(ab) = J(cd) not equal J(bc) = J(da)) was established. An extended Bogoliubov transformation was developed by solving an equation group, consisting of 20 equations and 20 unknowns. The procedure for solving the equation group was carried out by introducing a simple way of reducing the numbers of the equations and the unknowns. The spin-wave spectra in the present system have been determined by performing the standard Holstein-Primakoff transformation and the Bogoliubov one. It has been found that the spin-wave spectra of the present system depend on the exchange constants and that the degeneracy of the spin-wave spectra remains. The results for a special case (J(ab) = J(bc)) i.e., an antiferromagnet are discussed briefly. The spin-wave spectra of the four-sublattice Heisenberg antiferromagnet are found to be degenerative also and they are linear in k for small k.
关键词:
model
于锦
,
杨冬梅
,
蒋军辉
,
王之昌
中国有色金属学报
溴化稀土在948K以下时蒸气压极小, 以至于无法测出.研究显示, 可能是由于生成气态配合物NdyAlxBr3(x+y), 溴化钕与溴化铝在600K以上共热时, 溴化钕的表观蒸气压大幅度提高.平衡实验结果表明, 在温度为629～805K和压力为0.015～0.19MPa时, NdAl3Br12 是惟一的稳定气态配合物.反应式NdBr3(s)+(3/2) Al2Br6(g)=NdAl3Br12(g)的平衡常数由骤冷实验结果计算.假设ΔC(-)p=0J·mol-1·K-1, 该反应的焓变和熵变分别为ΔH(-)298=25.5±2.0kJ/mol和ΔS(-)298=-2.6±3.0J·mol-1·K-1.
关键词:
稀土
,
NdAl3Br12
,
气态配合物
,
骤冷法
,
热力学性质
Y.G. Cao
,
X.Y. Sun
金属学报(英文版)
J-integral and crack opening displacement δ(COD) were important parameters for characterization of fractures in engineering materials. The relationship between J-integral and COD has been investigated for a long time and was enerally represented as J = m σyδ, where σy is the yield strength and m is a function of specimen geometry and material properties. To determine the value of m, extensive studies and experiments have been performed. The method that used the fracture-surface topography analysis (FRASTA) for determining J-integral from fracture surfaces of materials was introduced. On the basis of the relationship between COD and fracture surface average profile, the relationship between J-integral and COD was deduced and compared with the generally used equation. The method was experimentally confirmed to be able to provide a new way to determine the relationship between J-integral and COD.
关键词:
FRASTA
,
null
,
null
null
,
null
金属学报
在工程上,经常由于应力腐蚀开裂和氢脆引起中强度钢结构件发生滞后破坏。这类脆断往往从结构件中预先存在的疲劳或焊接裂纹处开始,因此,运用传统的光滑试样的检验方法不能反映这类破坏的特点。 本文将弹塑性断裂力学中的J积分概念用于滞后破坏的研究,提出用带预制疲劳裂纹的悬臂弯曲试样测定J积分的临界值J_(Ic)和应力腐蚀开裂阈值J_(Iscc)的方法。测定了40CrNiMo钢的J_(Ic)值及其在硫化氢水溶液中的J_(Iscc)值。通过和三点弯曲方法测定的J_(Ic)值的对比,以及和满足线弹性条件时直接测定的应力强度因子K_I值的对比,说明这种方法的可靠性。最后,对悬臂弯曲方法的特点进行了讨论。
关键词:
姚元勇
,
吴兰艳
,
舒华
,
唐帮成
,
薛伟
应用化学
doi:10.3724/SP.J.1095.2014.40052
以芳香胺和肉桂醛为原料,合成的芳香族亚胺为亲电试剂,亚磷酸二乙酯或亚磷酸三乙酯为亲核试剂,在10％(摩尔分数)磷酸催化剂(Brφnsted acid)的作用下,通过催化剂与亲电试剂、亲核试剂之间共同形成的双氢键或单氢键的作用,成功地合成了α-氨基膦酸酯类化合物,收率可达到79％～85％.
关键词:
Brφnsted酸
,
α-氨基膦酸酯
,
氢键作用
,
催化
,
磷氢化反应
唐海欧
,
丁运生
,
吴淑莹
,
张效敏
,
熊仁艳
,
陈龙
,
查敏
,
李长林
高分子材料科学与工程
应用离子液体[C_(14)mim]Br和线型低密度聚乙烯(LLDPE)熔融共混,制备出LLDPE/[C_(14)mim]Br共混物,并对共混物结构与性能进行了表征与测试.结果表明,随着[C_(14)mim]Br在共混物中含量的增加,LLDPIE晶粒尺寸变大,而且在相同的降温速率下,[C_(14)mim]Br使LLDPE起始结晶温度提高,表明[C_(14)mim]Br起到了异相成核的作用.[C_(14)mim]Br加入量为2.0 phr时,材料抗静电性能最好,表面电阻为1.8×10~8Ω.随着[C_(14)mim]Br添加量的增加,材料的熔融指数有增加的趋势,而且材料拉伸强度先增大,后逐渐减小,冲击强度先减小,后逐渐增大,[C_(14)mim]Br起到了反增塑与增塑的作用.
关键词:
N-十四烷基-N'-甲基溴化咪唑盐
,
线型低密度聚乙烯
,
共混
,
结构与性能
