共查询到16条相似文献,搜索用时 78 毫秒
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综述了SiC/Si3 N4 复合粉体的力学性能和制备方法 ,提出了一种制备纳米级SiC/Si3 N4 复合粉体的新方法 ,并通过热力学分析提出了合成条件 相似文献
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理想化学计量纳米氮化硅的制备 总被引:4,自引:0,他引:4
本文研究了激光诱导化学气相沉积纳米氮化硅的制备工艺过程,提出了减少游离硅的措施,利用光学二步激励法得到了理想化学计量的高纯纳米氮化硅粉末,其N/Si比 1.321,非常接近于理想值4/3(1.333)。 相似文献
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石墨烯是由sp2杂化的碳原子键合而成的具有六边形蜂窝状晶格结构的二维原子晶体,其具有电学、力学和光学等方面一系列优良性能,使得它在各个领域的应用一直被人们所关注。然而,石墨烯的工业化制备仍然面临着巨大的挑战。本文采用化学气相沉积法(CVD)制备石墨烯,并用拉曼光谱、高分辨率扫描电镜和X射线多晶衍射对其进行了分析和表征。研究结果表明,用CVD法制备石墨烯具有工业化的可能。 相似文献
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利用电子回旋共振等离子体化学气相沉积(ECR—CVD)技术,以SiH4和N2为反应气体进行了氮化硅钝化薄膜的低温沉积技术的研究。采用原子力显微镜、傅立叶变换红外光谱和椭圆偏振光检测等技术对薄膜的表面形貌、结构、厚度和折射率等性质进行了测量。结果表明,采用ECR—CVD技术能够在较低的衬底温度条件下以较高的沉积速率制备厚度均匀的氮化硅薄膜,薄膜中H含量很低。薄膜沉积速率随微波功率和混合气体中硅烷比例的增加而增大。折射率随微波功率的增大而减小,随混合气体中硅炕比例的增大而增大。在相同气体混合比和微波功率条件下,较高衬底温度条件下制备的薄膜折射率较大。 相似文献
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We have found that SiN passivation by catalytic chemical vapor deposition (Cat-CVD) can significantly increase an electron density of an AlGaN/GaN heterostructure field-effect transistor (HFET). This effect enables thin-barrier HFET structures to have a high-density two-dimensional electron gas and leads to suppression of short-channel effects. We fabricated 30-nm-gate Al0.4Ga0.6N(8 nm)/GaN HFETs using Cat-CVD SiN. The maximum drain current density and extrinsic transconductance were 1.49 A/mm and 402 mS/mm, respectively. Current-gain cutoff frequency and maximum oscillation frequency of the HFETs were 181 and 186 GHz, respectively. These high-frequency device characteristics are sufficiently high enough for millimeter-wave applications. 相似文献
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The effect of fluidized bed (FB) treatment upon hot filament chemical vapor deposition (HFCVD) of polycrystalline diamond films onto WC-Co hardmetal substrates was investigated. Several scenarios to make the substrates ready for HFCVD were, comparatively, evaluated and the resulting diamond films were examined in terms of their morphology and adhesion. The diamond grain density was measured by scanning electron microscopy. The adhesion of continuous diamond film to substrate was evaluated by the reciprocal of the slope of crack radius-indentation load functions. Surface binder dissolution followed by FB treatment (PF pretreatment) allowed very high diamond nucleation density and smaller grain size. The adhesion of films grown on PF pretreated substrates was found to be very close to that of films deposited on hardmetal slabs pretreated by Murakami's reagent followed by Co etching with Caro's acid and seeded with diamond suspension in an ultrasonic vessel (MPS pretreatment). However, diamond coatings on MPS pretreated samples exhibited a rougher surface morphology as a result of both lower diamond nucleation density and larger substrate surface roughening by Murakami's etching. Based upon experimental findings, our newly developed PF pretreatment was found to be a very promising technique in substrates conditioning as well as in promoting adherent, uniform and smooth diamond coatings onto hardmetal tools and wear parts. 相似文献
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In this paper, we report a simple approach to synthesize silicon carbide (SiC) nanowires by solid phase source chemical vapor
deposition (CVD) at relatively low temperatures. 3C-SiC nanowires covered by an amorphous shell were obtained on a thin film
which was first deposited on silicon substrates, and the nanowires are 20–80 nm in diameter and several μm in length, with
a growth direction of [200]. The growth of the nanowires agrees well on vapor-liquid-solid (VLS) process and the film deposited
on the substrates plays an important role in the formation of nanowires. 相似文献
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Although the high impermeability of graphene makes it an excellent barrier to inhibit metal oxidation and corrosion, graphene can form a galvanic cell with the underlying metal that promotes corrosion of the metal in the long term. Boron nitride (BN) nanosheets which have a similar impermeability could be a better choice as protective barrier, because they are more thermally and chemically stable than graphene and, more importantly, do not cause galvanic corrosion due to their electrical insulation. In this study, the performance of commercially available BN nanosheets grown by chemical vapor deposition as a protective coating on metal has been investigated. The heating of the copper foil covered with the BN nanosheet at 250 °C in air over 100 h results in dramatically less oxidation than the bare copper foil heated for 2 h under the same conditions. The electrochemical analyses reveal that the BN nanosheet coating can increase open circuit potential and possibly reduce oxidation of the underlying copper foil in sodium chloride solution. These results indicate that BN nanosheets are a good candidate for oxidation and corrosion protection, although conductive atomic force microscopy analyses show that the effectiveness of the protection relies on the quality of BN nanosheets. 相似文献