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1.
石墨—MDF水泥基复合材料屏蔽电磁波性能   总被引:7,自引:0,他引:7  
研究了石墨、聚合物(PVA)及材料厚度对石墨-MDF(Macro-Defect-Free)水泥基复合材料屏蔽电磁性能的影响及其机理。结果表明:当石墨添加量超过18v.%时,材料对2001600MHz的电磁波有10-40dB的衰减效果,屏蔽效率S随材料中聚合物增加而降低,随材料厚度增加而升高,随电磁波的频率f的增加有升高的趋势。当石墨在水泥基体里形成导电网络时,材料的电阻率pv发生显著变化,即出现渗  相似文献   

2.
以硫铝酸盐水泥为基材,采用有机聚合物PVA,并且在MDF(Macro—Defect—Free)水泥中添加偶联剂KH,制备出抗折强度大于170MPa,抗压强度达240MPa的新型MDF水泥、同时,借助于X射线光电子能谱分析(XPS),红外光谱分析(IR)等测试手段研究了偶联剂KH和聚合物PVA在硫铝酸盐-MDF水泥中的作用机理  相似文献   

3.
各向异性的粘结钕铁硼/铁氧体永磁复合材料的磁性能   总被引:2,自引:0,他引:2  
刘颖  敬安晋 《功能材料》1999,30(4):352-352,360
采用高性能的各向异性HDDR-Nd-Fe-B磁粉和铁氧分与塑料复合,制成了各向异性粘结NdFeB/铁氧体复合永磁材料研究了它们的磁性能。结果表明,随HDDR-Nd-Fe-B含量增加,各向异性的塑料粘结HDDR-Nd-Fe-B/铁氧体复合永磁材料磁性能bHc和密度几乎是线性增大,而jHc,(BH)max和Bc开始都增大,当达到一定值后基本保持不变,出现一平台,随后又继续增大,但jHc与Br和(BH)  相似文献   

4.
偶联剂KH和聚合物PVA在硫铝酸盐—MDF水泥中的作用机理   总被引:2,自引:0,他引:2  
以硫铝酸盐水泥为基材,采用有机聚合物PVA,并且在MDF水泥中添加偶联剂KH,制备出抗折强度大于170MPa,抗压强度达240MPa的新型MDF水泥。同时,借助于X射线光电子能谱分析(XPS),红外光谱分析(IR)等测试手段研究了偶联剂KH和聚合物PVA的硫铝酸盐-MDF水泥中的作用机理。  相似文献   

5.
Fe73.5Cu1Mo3Si13.5B9非晶合金的晶化动力学   总被引:2,自引:0,他引:2  
用DTA,结合XRD,TEM研究了Fe73.5Cu1Mo3Si13.5B9软磁非晶合金的晶化动力学,结果表明,该合金在478℃时析出a-Fe相,晶化初期激活能量最小(148kJ.mol^-1),它随晶化学量的增加而增大,在XC为50-78%时,呈极大值(510kJ.mol^-1)随退火温度的升高,α-Fe相的数目增多,但尺寸基本不变。为14-16mm。  相似文献   

6.
利用光滑和缺口试件研究了一种工业氧化铝陶瓷的动疲劳特性,给出了一种预测疲劳强度的简便方法,当加载速率σ〈σc时(σ≈20MPa)试件的动疲劳强度σDF随σ增大而升高,当σ〉σc,趋势出现逆转,对于应力集中系数K1不同试件,σDF-σ关系曲线相互平行,并可用参量K1σDF归一化。统计分析显示,疲劳强度有可能遵从正态分布或对正态分布,采用本文定义的等效应力,可获得光滑及接口试件的统一SPT(Stren  相似文献   

7.
推帚式TDI—CCD成象时象移影响的分析   总被引:4,自引:3,他引:1  
通过对TDI-CCD的成象特点分析和对象移调制传递函数MTFv的计算,表明当采用连续四相驱动时,MTFv可达到0.974,基本上消除了象移的影响。  相似文献   

8.
研究了交替马来酸酐共聚物多缩乙二醇酯(BM350)-LiBF4络合物的离子传导性能.实验表明:络合物的侧链玻璃化转变温度随盐含量的增加而上升电导率随盐浓度的变比而出现一极大值室温电导率最大可达419×10-5S·cm-1.电导率随温度升高而增加.络合物的导电行为符合VTF方程.无定形相中分子链热运动是离子传输的动力。  相似文献   

9.
深入研究了交替马来酸酐共聚物多缩乙二醇酯(BM350)-LiCF2SO3两种碱金属盐络合物的离子传导性能。实验结果表明,室温电导率最大可达5.08×10~(-5)S·cm~(-1)。络合物的玻璃化转变温度随盐含量的增加而上升。电导率随盐浓度的变化而出现一极大值。电导率均随温度升高而增加。络合物的导电行为符合VTF方程。高弹态中分子链热运动是离子传输的动力。  相似文献   

10.
以聚六亚甲基碳酸酯二醇(PHMCD)和聚四亚甲基醚二醇(PTMEG),4.4’-对二苯基甲烷二导氰酸酯(MDI)及1.4-丁二醇(BDO)合成线型聚碳酸酯聚氨酯,研究了其软段相的Tg,力学性能和流变特性。结果表明随PHMCD含量增大,聚合物的拉伸强度增加,而熔体的表观粘度则降低。  相似文献   

11.
In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.  相似文献   

12.
13.
Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……  相似文献   

14.
A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.  相似文献   

15.
On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……  相似文献   

16.
Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.  相似文献   

17.
In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M2(B,C), (W,Mo)2(B,C), M3(B,C), M23(B,C)6 type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm2. The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K1 mill housing of bar mill.  相似文献   

18.
The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ...  相似文献   

19.
Several researches have been reported about the characteristic of β-Ga2O3 nanowires which was synthesized on nickel oxide particle. But indeed, recent researches about synthesis of β-Ga2O3 nanowires on oxide-assisted transition metal are limited to nickel or cobalt oxide catalyst. In this work, Gallium oxide (β-Ga2O3 ) nanowires were synthesized by a simple thermal evaporation method from gallium powder in the range of 700 - 1000℃ using the iron, nickel, copper, cobalt and zinc oxide as a catalyst, respectively. The β-Ga2O3 nanowires with single crystalline without defects were successfully synthesized at the reaction temperature of 850, 900 and 950℃ in all the catalysts. But optimum experimental condition in synthesis of nanowires varied with the kind of catalyst. As increasing synthesis temperature,the morphology of gallium oxide nanowires changed from nanowires to nanorods, and its diameter increased. From these results, we could be proposed that the growth mechanism of β-Ga2O3 nanowires was changed with synthesis temperature of nanowires. Microstructure and morphology of Synthesized nanowire was characterized by HR-TEM, FE-SEM, EDX and XRD.  相似文献   

20.
正Responding to ISO’s appeal for survey for the to-be-developed ISO Strategy Plan for 2016-2020,SAC hosted a special workshop over the needs and comments of various fi elds on June 8 in Beijing.The workshop was attended by ISO President-elect and Ansteel General Manager Zhang Xiaogang,SAC Vice-Administrator Yu Xinli,and 30 experts from  相似文献   

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