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Search Results: 1 - 10 of 3509 matches for " 起皮开裂 "
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绝缘子水泥胶合剂表面起皮开裂影响因素探讨
卢声彦,于清波,窦刚,卢时超
电瓷避雷器 , 2014,
Abstract: 主要研究了电瓷绝缘子经过蒸汽养护以后,水泥胶合剂表面出现起皮开裂现象的各种可能性因素。通过对水泥胶合剂的原材料应用、胶装组件、养护条件三方面进行针对性试验,发现直接影响水泥胶合剂表面起皮开裂的主要因素有胶合剂水分、减水剂种类及用量、蒸汽养护温度及养护过程中冷水注入。在胶合剂的配制过程中,对水分、减水剂的种类及用量进行有效控制,在产品的蒸汽养护阶段,严格控制冷凝水不能过早集聚在胶合剂表面,养护温度控制在50℃以下,保证空间内温度均匀,可以有效避免水泥胶合剂表面起皮开裂现象出现。
压缩载荷作用下分支裂纹断裂与扩展的数值和实验研究
李碧勇,朱哲明
煤炭学报 , 2013,
Abstract: 材料中裂纹形态比较复杂,有弯曲,交叉或者分支等等,通过数值和实验的方法研究了在压缩载荷作用下分支裂纹的断裂问题,考虑分支裂纹倾角和长度对应力强度因子和裂纹扩展的影响。结果表明:裂纹倾角的增加使I型应力强度因子减小,而裂纹长度的增大使应力强度因子增大,长度较大的分支裂纹对长度较小的有一定的抑制作用。通过对张开型分支裂纹和弯折裂纹砂岩试件的单轴压缩试验,发现砂岩试件的破坏形式主要是以I型翼型裂纹扩展为主,其起裂位置距离裂纹尖端的距离随着分支裂纹角度的增大而减小;分支裂纹倾角越大,其翼型裂纹起裂角就越小但相应的起裂载荷却越大。还对张开型裂纹和闭合型裂纹做了一定的比较,发现张开型裂纹的起裂角要大于闭合型裂纹的起裂角,但其起裂载荷却正好相反。
Inhibitive Role and Mechanism of Water-Soluble Polymer PVP on the Surface-Exfoliation Problem of Ceramic Green Bodies Prepared byGelcasting
水溶性高分子PVP对陶瓷凝胶注模成型坯体表面起皮的抑制作用与机理

MA Jing-Tao,XIE Zhi-Peng,MIAO He-Zhuo,HUANG Yong,CHENG Yi-Bing,
马景陶
,谢志鹏,苗赫濯,黄勇,程一兵

无机材料学报 , 2002,
Abstract: The inhibition of oxygen, which occurred in gelcasting during the formation of polymer networks by in-situ polymerization of monomers in air, was successfully prevented by adding a proper amount of polyvinylpyrrolidone (PVP) to the aqueous acrylamide solution. Thus, the surface-exfoliation problem of green bodies was eliminated and the aim of precisely controlling the size of the formed green bodies was achieved by gelcasting in air. The influence of PVP on the dispersion of alumina, the static and dynamic rheological properties of alumina slurry and the strength and microstructure of green bodies was investigated. Furthermore, the mechanism of PVP in eliminating the surface-exfoliation problem of green bodies gelcast in air, namely the role of PVP in thickening and the hydrogen bonding between the molecules of PVP, which serve as a ceramic binder for the particles on the sample surface, was analyzed via the infrared spectra.
Dynamic scaling behaviour of late-stage phase separation in Ni75AlxV25-x alloys
Li Yong-Sheng,Chen Zheng,Lu Yan-Li,Xu Guo-Dong,
李永胜
,陈 铮,卢艳丽,徐国栋

中国物理 B , 2007,
Abstract: The dynamic scaling behaviour of late-stage phase separation and coarsening mechanisms of L12 and D022 in Ni75AlxV25-x (3 \le x \le 10$, at.%) alloys are studied using the microscopic phase-field dynamic model. The microelasticity field is incorporated into the diffusion dynamic model. The results show the morphology and coarsening dynamics being greatly changed by the elastic interactions among different precipitates, the particles aligning along the dominant directions, the average domain size (ADS) of L12 and D022 deviating from the exponent of temporal power-law, and the growth slowing down due to the increasing of elastic interactions. The dynamic scaling regime of late-stage coarsening of the precipitates is attained. Thus the scaling behaviour of structure function is also applicable for elastic interaction systems. It is also found that the variations of ADS and scaling function depend on the volume fraction of precipitates.
氘致纯Pd开裂机理
孙大林,雷永泉,陈仰霖,吴京,王启东
金属学报 , 1992,
Abstract: 本文在光学显微镜和透射电镜下观察到退火态纯Pd经290h电化学充氘后,位错密度从充氘前的10~8/cm~2增加至10~(12)/cm~2以上,并产生许多类似气泡的空洞组织或裂纹。分析认为形成空洞或裂纹的原因是由于氘原子沿位错周围富集,D-D原子间重新复合成D_2分子所致,X射线衍射表明,充氘290h后,Pd晶体的点阵常数从0.3890增大到0.4034nm。
某压力容器封头焊缝开裂分析
刘华
材料工程 , 2007,
Abstract: 某压力容器封头在打压实验过程中焊缝开裂,采用扫描电镜、光学显微镜对断口特征和金相组织进行了观察,并对焊缝的显微硬度、氧和氢含量等进行了检测,在综合分析的基础上,确定了封头焊缝开裂原因。结果表明封头焊缝开裂是由于在焊接过程中,焊缝内表面保护不良而形成氧化层及富氧α层,加之封头吊耳焊缝与环形焊缝叠加处具有一定的应力集中和相对较高的残余应力,从而在压力实验过程中造成焊缝开裂。
起旋器出口断面流速分布与起旋效率
孙西欢?,王文焰?,武鹏林?
西北农林科技大学学报(自然科学版) , 2000,
Abstract: 通过对6种起旋器、4种流量工况的试验,对起旋器出口断面流速分布及起旋效率进行了分析。结果表明,起旋器出口断面轴向流速分布呈类对数型分布,它比平直流的流速分布更均匀,可以用平直流速分布公式与一个二次尾流函数来表示;起旋器出口断面周向流速分布在主流区近似呈线性分布。提出了起旋器的起旋效率计算式,公式表明要提高起旋效率,则必须减小阻力损失,即应对起旋器结构参数进行优化。
滋阴起痿汤治疗阳痿50例临床观察
杨宝贵
中国中医药信息杂志 , 2007,
Abstract:
High Temperature Oxidation of FGH96 P/M Superalloy
HIGH-TEMPERATURE OXIDATION OF FGH96 P/M SUPERALLOY

FJ Liu,MC Zhang,JX Dong,Y W Zhang,
F.J.
,Liu,M.C.,Zhang,J.X.,Dong,Y.,W.,Zhang

金属学报(英文版) , 2007,
Abstract: High temperature oxidation behaviors of FGH96 P/M superalloy have been studied in air at temperatures ranging from 600 to 1000℃. By means of isothermal oxidation testing,X-ray diffraction, SEM (scanning electron microscopy), and EDS (energy dispersive X-ray spectroscopy) analyses, the oxidation kinetics as well as the composition and morphology of scales were investigated. Thermodynamic calculations were used to explain the oxidation mechanism. The results showed that as the oxidation temperature increased, the oxidation rate, the scale thickness, and scale spallation increased. FGH96 P/M superalloy exhibits good oxidation resistance at temperature below 800 ℃. The oxidation kinetics follows an approximately parabolic rate law, and the oxide layer was mainly composed of Cr2O3, TiO2,and a little amount of NiCr2O4. The oxidation is controlled by the transmission of chromium,titanium, and oxygen through the oxide scale.
基于损伤的钢筋混凝土锈胀开裂模型
王治,金贤玉,付传清,徐振楠,钱婷婷
建筑结构学报 , 2014,
Abstract: 基于混凝土的各向异性损伤,建立考虑钢筋、腐蚀产物、混凝土三者不同力学性能的钢筋锈胀导致保护层开裂的数学模型。模型考虑了腐蚀产物对钢筋混凝土界面区的孔隙和混凝土开裂裂缝的填充效应,采用非线性分析算法,预测了开裂过程中混凝土构件的应变与位移以及混凝土保护层开裂时间。最后将模型预测值与试验结果进行对比,结果表明:当混凝土出现裂缝之后,混凝土产生软化、腐蚀产物对裂缝进行填充,从而使混凝土环向拉应变的增长速率减缓;在选定钢筋的型号、直径以及混凝土强度之后,可通过增大保护层厚度来减小钢筋锈胀开裂的风险。
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