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31.
用50W连续波CO_2激光器为热源,诱发SiH_4和C_2H_4反应,合成SiC超细粉末。实验确定了反应腔体内压力p、气源中的C/Si原子比、喷嘴内径2r以及激光功率密度与粉末特性之间的关系,并对合成的产物进行物理、化学表征。 相似文献
32.
本文研究了采用锁定放大相干检测技术的等离子体光发射谱检测系统。用该系统检测了仅用CF4作为刻蚀气体刻蚀非晶硅基薄膜的等离子体光发射谱。分析了检测结果和刻蚀机理。 相似文献
33.
本文主要介绍了硅中硼离子注入校准样品的制备与研究。分别用三台SIMS仪器对样品进行了深度剖析与比对,并对用作校准目的的样品主要参数进行了定值。 相似文献
34.
Hongyu Wang Yolande Berta Gary S. Fischman 《Journal of the American Ceramic Society》1992,75(5):1080-1084
The microstructure of silicon carbide whiskers synthesized by carbothermal reduction of silicon nitride has been studied using transmission electron microscopy. All of the whiskers examined are single crystals, and grow in the (111) crystallographic direction. Two different forms of stacking faults and microtwins were observed; in one the planar defects are normal to the whisker growth direction, and the other has the defect planes at an angle of about 70° to the growth axis, while both forms of the defects are on the [111] closed-packed planes. Without the addition of catalyst, droplets containing metallic impurities were not found at the tips of the whiskers synthesized by the present process. A core and outer regions were observed in the single-crystal whiskers, which may be evidence that the whiskers were formed by a two-stage mechanism. 相似文献
35.
A silicide coating was prepared on Ti3SiC2-based ceramic by pack cementation to improve the oxidation resistance of Ti3SiC2, which is a technologically important material for high temperature applications. The microstructure, phase composition and
oxidation resistance of the coated sample were investigated. The results demonstrated that the silicide coating was mainly
composed of TiSi2 and SiC. A single layer of a mixture of SiO2 and TiO2 was formed on the surface of the coated sample during isothermal oxidation at 1100 °C and 1200 °C for 20h. Compared to Ti3SiC2, the parabolic rate constant of silicide coated Ti3SiC2 decreased by 2~3 orders of magnitude. Furthermore, the coated sample showed much better cyclic oxidation resistance than
Ti3SiC2 during the cyclic oxidation at 1100 °C for 400 times. However, during the preparation of the coating, a number of fine cracks
formed in the outer layer of the coating. When these cracks penetrated the whole coating during the cyclic oxidation, the
oxidation rate was accelerated, which degraded the oxidation resistance.
Electronic Publication 相似文献
36.
37.
In this paper we discuss the different models proposed to explain the visible luminescence in porous silicon (PS). We review
our recent photoluminescence and Raman studies on PS as a function of different preparation conditions and isochronal thermal
annealing. Our results can be explained by a hybrid model which incorporates both nanostructures for quantum confinement and
silicon complexes (such as SiH
x
and siloxene) and defects at Si/SiO2 interfaces as luminescent centres. 相似文献
38.
本文对氧化非晶硅磷掺杂的工艺条件进行了研究,得出掺磷氢化非晶硅的电导率随衬底温度、气体流量、气体压力、射频功率、淀积时间的变化关系,为非晶硅的有效掺杂和器件研究提供了依据。 相似文献
39.
Fracture toughness and fatigue crack propagation (FCP) of plain and modified anhydride-cured epoxy resin (EP) were studied at ambient temperature. Liquid carboxyl-terminated acrylonitrile-butadiene (CTBN) and silicon (SI) rubber dispersions were used as tougheners for the EP. The morphology of the modified EP was characterized by dynamic mechanical analysis (DMA) and by scanning electron microscopy (SEM). The fracture toughness, Kc, of the compositions decreased with increasing deformation rate. Kc of the EP was slightly improved by CTBN addition and practically unaffected by incorporation of the SI dispersion when tests were performed at low cross-head speed, v. Both modifiers improved Kc at high v, and also the resistance to FCP, by shifting the curves to higher stress intensity factor ranges, ΔK, by comparison with the plain EP. It was established that both fracture and fatigue performance rely on the compliance, JR, at the rubbery plateau, and thus on the apparent molecular mass between crosslinks, Mc. The failure mechanisms were less dependent upon the loading mode (fracture, fatigue), but differed basically for the various modifiers. Rubber-induced cavitation and shear yielding of the EP were dominant for CTBN, whereas crack bifurcation and branching controlled the cracking in SI-modified EP. The simultaneous use of both modifiers resulted in a synergistic effect for both the fracture toughness at high deformation rate and the FCP behavior. 相似文献
40.
树脂热解炭制备碳化硅晶须 总被引:6,自引:1,他引:5
用自制的配合醛树脂热解和炭源,用SIO2超细汾作原,根据碳热还原原理,利用常规加热和微波加热两种方式,分别制备了直径在纳米级的SiC晶须,X射线衍射、透射电检测结果表明:制备工艺和条件对SiC晶须的性质有较大的影响。 相似文献