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1.
热浸镀Al-2%Si钢带界面化合物层的组成和结构   总被引:1,自引:0,他引:1  
本文利用俄歇电子谱(AES)及透射电镜(TEM)对比分析了国产、日本、和西德热浸镀Al-2%Si钢带界面化合物层的厚度、结构和组成。结果表明,Si以Fe_2(AlSi)_5的形式存在于Fe_2Al_5结构的界面化合物中。与热浸镀Al相比,添加Si后导致界面化合物层厚度下降的原因在于Si填充了Fe_2Al_5结构中原子空位、阻碍了Al原子的扩散。  相似文献   

2.
高磁导率猛锌铁氧化的ZnO过量研究   总被引:1,自引:0,他引:1  
本文叙述了用化学共沉法和普通的空气中烧结,真空冷却工艺,制备了μi为10000的MnZn铁氧体材料,配方中ZnO过量2mol%,能提高μi30%。文中对高μi锰锌铁氧体性能和结构进行详细的研究。  相似文献   

3.
郭太良  高怀蓉 《功能材料》1994,25(5):402-405
采用碱锑化合物的镀制与铯氧激活可制备复合型Si光电发射材料(Si-Na_2Sb-Cs)-O-Cs,(Si-K_3Sb-Cs)-O-Cs,(Si-Cs_3Sb-·Cs)-O-Cs和(Si-Na_2KSb-Cs)-O-Cs,其最高灵敏度分别可达950,1050,150和2000μA/1m,其最低逸出功分别已达1.0,0.9,0.85和0.9eV。比较了复合型Si光电发射材料与Si和Na_2KSb(Cs)光电材料的一些性能参数,提出了复合型Si光电材料的表面原子模型;讨论了复合型S光电材料的光电发射过程并分析了碱锑过渡层的作用。  相似文献   

4.
从SiC晶须性能及晶须表面氧化层特性角度研究分析了SiC晶须特性对其在Si_3N_4陶瓷基体中补强、增韧行为的影响。结果表明,晶须的直径、长径比值正比于晶须补强、增韧Si_3N_4陶瓷基体的能力。表面粗糙晶须对Si_3N_4复合材料的强度影响不大,却能显著地改善其韧性。晶须表面氧化层增厚,表面氧化硅从Si-O单键形式转化成为SiO_2后,晶须在Si_3N_4基体中的补强、增韧效果非但没有降低,还略有增加。  相似文献   

5.
微波铁氧体吸收剂复磁导率和复介电常数的温度特性研究   总被引:4,自引:0,他引:4  
张秀成  赵振声 《功能材料》1994,25(2):169-171
本文对(Zn_(1-x)Co_x)_2-w型六角晶系铁氧体吸波材料的复磁导率μ_r和复介电常数ε_r的温度特性进行了研究。实验发现当温度从-25℃升至100℃时,复磁导率的实部μ'_r值从1.51降至1.30,虚部μ″_r值从0.19降至0.14,复介电常数的实部ε′_r值从6.50升至7.10,虚部ε″_r值从1.70升至1.80,理论上对电磁参数随温度变化特性进行了分析讨论。  相似文献   

6.
利用EPMA和XRD的分析方法,研究了Si_3N_4-Al_2O_3-ZrO_2系陶瓷材料表面氧化层组成。结果表明,Si_3N_4-Al_2O_3-ZrO_2系陶瓷材料表面氧化层是由方石英相、ZrSiO_4相和含有Al_2O_3、CaO等的SiO_2玻璃相所组成,其中SiO_2玻璃相中Al_2O_3、CaO等的含量,随着氧化时间的增加而逐渐增加。  相似文献   

7.
Fe-25.6Mn-5.1Si-4.1Ni-1.8Co(wt%)合金在一80℃变形时,可逆应变量ε_r随预应变量ε_t增大而迅速增大;当ε_t>2.5%,增大速度减慢;当4.2%<ε_t<10.8%,ε_r基本保持恒定值。逆相变温度A_f随ε_t增大而连续升高,但A_s不随ε_t变化。应力诱发ε马氏体及其逆相变后的残留显微组织分析表明,应力诱发ε马氏体片在形成过程中因相互交叉产生塑性变形,引起稳定化,是引起多晶Fe-Mn-Si系合金可逆应变量低的一个重要原因。文中还讨论了应力诱发ε马氏体稳定化的特点及可能的改善途径。  相似文献   

8.
反应烧结Si_3N_4陶瓷及零件的研制EI   总被引:1,自引:0,他引:1  
李凤梅 《材料工程》1995,(12):10-12
本文研究了成分配比对反应烧结氮化硅的烧结密度及相组成的影响,发现采用Y_2O_3和La_2O_3为烧结助剂时,在不加入其它催化剂的条件下,配合料中硅粉的最佳添加量为12~30wt%。采用热压铸成型与反应烧结相结合的工艺,可用Si_3N_4陶瓷制造出陶瓷发动机叶片等零件。  相似文献   

9.
Ti-Si-Nd纳米复合材料的微观结构   总被引:1,自引:0,他引:1  
加入6mg·g(-1)Nd的非晶Ti_(80)Si_(20)合金,在550—700退火1h后,可形成Ti_3Si基体相与弥散分布的α—Ti颗粒组成的纳米复合材料.X射线及电子衍射分析表明:在晶化过程中,初始析出相为小颗粒的α-Ti,随后析出主相Ti_3Si和少量Ti_5Si_3,但未见稀土相形成.用高分辨电镜研究了Ti_3Si的亚晶结构.  相似文献   

10.
本文研究了NdFeB-铁氧体-塑料3者复合成的永磁材料的复合效应。结果表明塑料粘结NdFeB-铁氧体复合材料的_bHc、_jHc、(BH)_m随NdFeB含量增加而升高,呈中间偏凹的趋势,压缩强度和硬度下降;同时随着塑料含量增加,磁性能B_r,_bHc,(BH)_m降低,而内禀矫顽力_jHc却上升。  相似文献   

11.
A method is proposed for estimating the parameters of a mixture of exponential and Weibull distributions for which the accuracy of preliminary estimates obtained by graphical analysis is refined in accordance with the criterion of maximum likelihood. The efficiency of the proposed method is supported by the results of statistical modeling.  相似文献   

12.
A novel method for the determination of the optical properties of tissue from time-domain measurements is presented. The data analysis is based on the evaluation of the first moment and the second centralized moment, i.e., the mean time of flight and the variance of the measured distribution of times of flight (DTOF) of photons injected by short (picosecond) laser pulses. Analytical expressions are derived for calculation of absorption and of reduced scattering coefficients from these moments by application of diffusion theory for infinite and semi-infinite homogeneous media. The proposed method was tested on experimental data obtained with phantoms, and results for absorption and reduced scattering coefficients obtained by the proposed method are compared with those obtained by fitting of the same data with analytical solutions of the diffusion equation. Furthermore, the accuracy of the moment analysis was investigated for a range of integration limits of the DTOF. The moment analysis may serve as a comparatively fast method for evaluating optical properties with sufficient accuracy and can be used, e.g., for on-line monitoring of optical properties of biological tissue.  相似文献   

13.
14.
An approximate analytical expression is derived for the velocity of the front of the wave of change of boiling modes on a rod and on a plate. The impact of the Thomson effect and of the heater orientation in the gravity field is included. Adequate agreement is demonstrated between the derived relations and experimental data.  相似文献   

15.
Conventional methods for summation of direct measurement errors are considered. Conditions under which these methods provide consistent results are stated. It is proposed to utilize for characteristic of the total error, its interval estimator or the half-sum of the value obtained by adding up its arithmetic and geometric random errors.Translated from Izmeritel'naya Tekhnika, No. 4, pp. 10–12, April, 1995.  相似文献   

16.
由于空压机进气侧轴承箱蜗壳温度探头密封效果不好,使空压机及其后续管道受到油污染。后将温度探头的O形圈密封改为骨架油封,杜绝了轴承箱漏油问题。文章简介空压机的结构和技术参数,详细介绍了骨架油封的制作和优点。  相似文献   

17.
It is shown that conditions of attainment of marginal states in the material of structural components are formulated on the basis of analysis of force and deformation criteria of formation and development of destruction. The parameters of these criteria are data on types of structural materials, standard and special characteristics of their mechanical properties, structural forms of considered elements of the equipment, and their operating stress loading. In this case, the construction of a system of state equations for describing interrelation of current damage, external actions, and responses to them is based on the concept of calculating variations in properties of materials at all stages of the design life cycle.  相似文献   

18.
The article suggests a method of evaluating the microstructural inhomogeneity of deformation of metals by modeling. The method includes the measurement of deformations of metal according to meshes of a dividing grid with small base and the calculation of the distribution parameters of microdeformations in model representation. It is shown that the modeling method makes it possible objectively to evaluate the microinhomogeneity of deformation of metals independently of the chosen mesh size of the dividing grid. New structural characteristics are introduced: the base and wave of variation expressing the degree of crumbling or amalgamation of metal grains by inhomogeneity of deformation.Translated from Problemy Prochnosti, No. 7, pp. 40–44, July, 1991.  相似文献   

19.
20.
水三相点是开尔文热力学温度的唯一基准点,也是ITS-90国际温标重要的定义固定点。因此,水三相点不确定度分析对整个温标的建立、温度量值传递起着至关重要的作用。近3年来,中国计量科学研究院研制出一系列高质量的水三相点容器,加强了水三相点的研究,为不确定度的分析提供了更为可靠的实验依据。同时,不确定度的分析也是客观评价新研制容器性能的一个重要指标。因此,根据实验结果对新研制容器所复现的水三相点进行了不确定度评定。评定结果表明,其扩展不确定度为0.16mK(k=2.69,P=0.99)。  相似文献   

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