共查询到20条相似文献,搜索用时 781 毫秒
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柠檬酸盐法制备纳米晶SrCe0.95Yb0.05O3—α 总被引:5,自引:1,他引:4
用柠檬酸酸盐法合成了超细的SrCe0.95Yb0.05O3-α粉体。使用TG,DTA,XRD,TEM测试手段,对试样的特性进行了表征,由TEM知团粒粒径范围在40-60nm,由XRD计算出原始晶粒的精确尺寸14.78nm。 相似文献
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测定了Fe-33.7(wt)%Mn-5.22(wt)%Si形状记忆合金在不同变量和不同回复温度的热机械循环(简称“训练”)条件下的形状记忆效应(SME)。通过电子显微分析观察以应力诱发马氏体均为薄片层组织,在应变量过大或回复不良分的训练过程中,位错的增殖会破坏的这种片层组织并影响晶本学的可逆性,同时使形状记忆效应恶化。 相似文献
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羟乙基羧甲基纤维素(HECMC)的合成和性能研究 总被引:3,自引:0,他引:3
李红 《高分子材料科学与工程》1998,14(5):34-37,41
探讨了用氯乙醇代替环氧乙烷和一氯醋酸作醚化剂,不用分离中间产物合成HECMC。确定的最佳合成条件不仅适于合成低粘度的HECMC,也适于合成高粘度HECMC。合成的水溶性HECMC,其MS为0.22-2.0;DS为0.26-0.77。,在此范围内具有良好的水溶性,粘主稳定性,耐温性和抗盐化,比CMC,HEC的性能优越,并对合成的HECMC进行了结构表征。 相似文献
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DBM-g-PE与PVC的相互作用研究EI 总被引:5,自引:1,他引:4
采用固相接枝法制备了DBM-g-PE,用红外光谱分析证明了接枝物确实存在。PVC/CPE=100/5合金性能测定结果表明,添加5份接枝物的合金(A),缺口冲击强度、拉伸强度分别为18.2kJ/m2和53.0MPa;而添加5份PE的合金(B),其相应性能为5.1kJ/m2和33.8MPa。不加接枝物的合金(C),虽有高韧性,但拉伸强度却由53.0MPa降至50.2MPa。DSC、SEM的结果均表明,PE接枝DBM后与PVC的相互作用增强,与CPE协同作用能增韧、增强PVC,并探讨了其机理。 相似文献
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316L(Fe-17.5Cr13.5Ni-2.5Mo)不锈钢注入N离子后,其自由腐蚀电位E_0、孔蚀再钝化电位E_p及孔蚀电位E_r均大大提高。在大应变量下,疲劳寿命下降;在小应变量下,疲劳性能改善。在电位E_0作用下,其腐蚀疲劳寿命较高子注入前有所降低。在施加电位E_0-100mV时,其疲劳寿命较离子注入前提高。表面离子注入层的存在提高材料的循环应力。 相似文献
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用自制的旋臂式磨蚀实验仪,研究了高密度聚乙烯(HDPE)/顺丁橡胶、高密度聚乙烯和45^#钢在攀枝花尾矿矿浆中的磨蚀速率与磨蚀温度和磨蚀时间的关系。结果表明,在20-48℃时,W(HDPE/cis-BR)和W(HDPE)分别保持在0.17-0.20mm/a和0.22-0.30mm/a。在55℃时,W(HDPE/cis-BR和W(HDPE)分别增加至0.28和0.39mm/a,在20-55℃时,W( 相似文献
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4 各项功能数据设定816彩色照片冲扩机的各项功能,通过键盘操作,可以任意设置各种不同数据,现将设置数据的操作方法作一介绍。4-1 总控制数据(M—DATA)在MODE与0-4同时按下时能设置总平衡(对应五种宽度相纸能分别独立设定)、水平校正(CF0)(CF1)~(CF9)、键盘校正级差的各种数据。在此状态下,每按一次NOODR在显示屏上依次出现上述各种信息。4-1-1 总平衡数据同时按MODE0-4显示“彩色总平衡(MBL)、127、C=+000、M=+000、Y=+000、Y/N″,再按D-… 相似文献
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定义了二阶定向循环平稳统计量,提出了基于二阶定向循环平稳的信号分析方法。该方法将用于单通道实信号分析的二阶循环统计量扩展到复信号,并定义了正交双通道融合复信号的定向循环自相关、定向循环谱相关密度。为了验证该方法,利用转子试验台模拟滑动轴承旋转机械的油膜失稳故障以获取数据,分析结果表明该方法不仅能够提取系统在某一截面内的周期性振动特征,而且能够揭示转子在指定循环频率处的旋向。此外二阶定向循环谱相关密度在指定频率处的切片能显示更加丰富的转子频率耦合调制信息,试验结果验证了该方法的有效性。
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钢纤维混凝土在低周反复荷载下力学性能的研究 总被引:3,自引:2,他引:1
对钢纤维混凝土棱柱体试件做了低周轴心压缩循环加、卸载试验,试验采用恒位移控制,通过试验和参数研究,提出了钢纤维混凝土反复加、卸载应力~应变曲线方程及计算变形的公式,这些数学表达式简便且可根据材料特性进行调整,具有较广泛的适应性。 相似文献
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Y. Xiong X. Gong Y. Jiang 《Fatigue & Fracture of Engineering Materials & Structures》2018,41(7):1504-1513
The effect of initial texture on cyclic deformation behavior of extruded ZK60 magnesium (Mg) alloy was experimentally investigated under strain‐controlled loading with the strain amplitudes at 4%, 1%, and 0.35%. The testing specimens were taken from extrusion direction (ED), transverse direction (TD), and a material precompressed to 9.4% along the ED (ED?9.4%). At a high strain amplitude of 4%, the cyclic deformation modes of ED and ED?9.4% specimens are similar, and they experience twinning exhaustion → slip and detwinning exhaustion → slip during each loading cycle. At a medium strain amplitude of 1%, twinning‐detwinning is involved in the cyclic deformation, but different deformation mechanisms were observed in the 3 different specimens. Partial twinning‐complete detwinning mode dominates the cyclic deformation in the ED specimen, while partial detwinning‐retwinning mode occurs in the ED?9.4% specimen. For the TD specimen, both basal slip and tension twinning occur during cyclic deformation. At a low strain amplitude of 0.35%, dislocation slips dominate the deformation for the ED specimen with a few observable tension twins. For the ED?9.4% specimen, initially twined texture increases the ductility of the material and enhances fatigue life as compared with the other 2 specimens. 相似文献
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Low-cycle fatigue behavior of TC21 alloy with equiaxed α phase embedded in the β transformed matrix (EM) and full lamellar α phase (LM) was investigated. The results show that the EM microstructure possesses higher strength, ductility and longer fatigue life than those of the LM one. Dislocation structures are straight dislocation lines in both EM and LM; however, more dislocation tangles and debris were observed in the α than in the β phase. The planar slip predominates cyclic deformation in the α phase, and promotes strain concentration and crack initiation at α phase boundaries. 相似文献
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D. VENU KUMAR D. S. RAMACHANDRA MURTHY S. SEETHARAMAN S. K. GUPTA V. BHASIN K. K. VAZE H. S. KUSHWAHA 《Fatigue & Fracture of Engineering Materials & Structures》2004,27(11):1061-1072
Earthquake load, which is cyclic in nature and of short duration, is the main design basis accident load for designing the primary heat transport (PHT) piping components of Nuclear Power Plants. Adequate protection of piping components from the effects of earthquake requires detailed knowledge of strength and deformation characteristics of the components and assemblies making up the piping system. Fracture behaviour of 23 pipes was studied by conducting cyclic tests under four‐point bending. Fifteen pipes were of carbon steel (SA333 Grade 6) of 219 mm, 324 mm and 406 mm ODs and eight pipes were of stainless steel (AISI Type 304LN) of 168 mm OD with through‐wall circumferential crack. Six pipes were tested under displacement control and the rest under load control. The effect of various parameters such as location and size of initial crack in base metal and weld metal, cyclic load range and displacement increment on crack growth and number of cycles for failure was investigated. The investigations showed significant reduction in the fracture resistance under cyclic loading conditions. Crack growth equations have been proposed for carbon steel pipes with and without weld under cyclic tearing. 相似文献
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通过添加0.1%(质量分数)的单一稀土La和复合稀土Y-La,研究了两种含稀土的Ni-10Cr-5Al(质量分数,%)合金在1 100℃和1 200℃下的高温循环氧化行为。采用热重法并结合X射线衍射、扫描电子显微镜、能谱仪等,研究了合金的循环氧化动力学、氧化物的物相和组织成分等演变规律,分析了含稀土Ni-10Cr-5Al合金的氧化膜粘附性能在不同氧化温度下的差异及机制。结果表明,在1 100℃时,Ni-10Cr-5Al合金中添加0.1%(质量分数)的La或Y-La,不仅减少了氧化膜的厚度,而且因形成"钉扎"作用提高了氧化膜的粘附性,从而改善了合金的抗循环氧化性能。且复合添加Y-La的效果优于单一添加La的效果。但在1 200℃时,合金沿晶界的内氧化加快,反而恶化了合金的抗循环氧化性能。 相似文献
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Jean Conan Gerald Séguin 《Applicable Algebra in Engineering, Communication and Computing》1993,4(1):25-39
Given any finite fieldF
q
, an (N, K) quasi cyclic code is defined as aK dimensional linear subspace ofF
q
N
which is invariant underT
n
for some integern, 0 <n N, and whereT is the cyclic shift operator. Quasi cyclic codes are shown to be isomorphic to theF
q
[]-submodules ofF
q
N
where the product(gl)· is naturally defined as
0
+
1T
n
+...+
m
T
mn
if()=
0
+
1
+...+
m
m
.In the case where (N/n, q)=1, all quasi cyclic codes are shown to be decomposable into the direct sum of a fixed number of indecomposable components called irreducible cyclicF
q
[]-submodules providing for the complete characterisation and enumeration of some subclasses of quasi cyclic codes including the cyclic codes, the quasi cyclic codes with a cyclic basis, the maximal and the irreducible ones. Finally a general procedure is presented which allows for the determination and characterisation of the dual of any quasi cyclic code. 相似文献