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本文用X射线衍射和扫描电镜研究了ZrO2膜的晶体结构和显微组织。结果表明ZrO2膜的相结构为立方氧化锆(c-ZrO2),晶粒尺寸细微。发现ZrO2膜中存在具有{111}面织构柱状晶结构,这种结构可用基片负偏压消除。 相似文献
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为预防回转窑焚烧各部位结焦现象的发生,以回转窑焚烧炉各部位的结焦物为研究对象,利用扫描电子显微镜-能谱分析仪(SEM-EDS)和X射线衍射(XRD)对其微观结构进行观察,并分析其元素组成和主要物相构造。结果显示,回转窑小沉降室结焦物存在大量孔隙,二燃室底部结焦结构较为致密,这与内部积灰及气流速度不一致有关。从元素组成来看,主要有O、Si、Al、Ca、Fe、Na及少量的Mg、K、Zn、Ti等;从物相组成来看,Si O2、Ca Si O3、Fe Si O3为主要成分,但各部位也存在一定差异;从物相及元素组成来看,焚烧灰渣中的碱金属和Si O2反应生成低熔点共熔体是引起结焦的主要原因。 相似文献
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设计了一种具有较高强度、同时兼有良好电磁波屏蔽功能的复合板,该复合板以普通PVC板为基体,以高强度的Fe78Si13B9非晶态合金薄带状材料(简称非晶带材)作为增强材料。对Fe78Si13B9非晶带材和复合板的力学性能研究表明,非晶带材内部应力分布严重不均匀,在拉伸过程中始终处于弹性变形阶段,拉伸强度为1400—1500MPa;与PVC板相比,随着非晶带材铺层数的增加,复合板的拉伸强度和弯曲强度显著上升。复合板以4层非晶带材为宜,其拉伸强度为42MPa,较PVC板提高了130%,复合板的弯曲强度达54MPa,比PVC板的弯曲强度提高了1倍以上。 相似文献
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基于加热均匀性的微波干燥研究进展 总被引:1,自引:0,他引:1
微波干燥通过电磁场辐射物体而在其内部产生热量,促进物体内部水分向外部迁移,是一种先进的干燥技术。但是,微波干燥存在加热不均匀的问题。本文针对该问题,分析了导致微波加热/干燥不均匀的影响因素,综述了通过提高微波干燥室内电磁场分布均匀性及改变被处理物料位置,以改进微波加热均匀性的可行措施,最后指出进一步实现微波均匀干燥的研究发展趋势。 相似文献
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目前许多学者致力于研究低温保存过程中生物组织材料的力学性能。在冷灌注过程中,内部温度的不均匀导致组织产生热应力,对生物组织造成损伤。为了更好地了解这一现象,研究重点定量考察温度与线性热膨胀系数和杨氏模量的关系,并应用一种新的方法测量肾脏组织在降温过程中产生的热应变。这种方法是利用低温显微系统获取不同降温速率下的肾脏组织图像,然后应用Vic-2D软件分析肾脏组织在特定温度和参照温度下所拍图像之间的微小形变,从而获得热应变数值。而杨氏模量是利用静态拉伸法测定不同温度下组织应力及应变,拟合出其杨氏模量数值。实验结果显示在0~20℃内,线性热膨胀系数是随着温度的降低而升高的;而杨氏模量在这个温度范围内保持恒定。 相似文献
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纤维素衍生物,如乙基纤维素,甲基纤维素,乙基氰乙基纤维素,乙基醋酸纤维素等与二氯乙酸所形成的溶液在浓度达到临界值以上后,出现胆甾型液晶相。在这类溶液中,液晶相的织态结构具有多重性,即胆甾型液晶相的织构随溶液浓度和温度而变化。在不同的浓度范围内,溶致性液晶可呈现出圆盘织构,条纹织构,假各向同性织构和具有鲜艳色彩的平面织构。这些织构均具有胆甾型液晶的特征。在液晶相刚形成,溶液处于 相似文献
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A micro-focus synchrotron beam has been used to investigate crystallographic texturing in poly(p-phenylene benzobisoxazole) fibres. By generating diffraction patterns across single fibres, it is possible to produce profiles showing scattering intensity as a function of beam position across the fibre. A straightforward model has been developed to allow the degree of texturing to be quantified for direct comparison between fibre types. The experimental results are found to fit a radial fibrillar-texturing model, which incorporates a distribution in radial orientation about the fibre axis. Previous studies reporting the a-axis of the PBO unit cell to be aligned radially within fibrils about the fibre axis are found to be correct.The degree of radial fibrillar texturing is in the same fibre order as tensile modulus and crystalline domain orientation for PBO fibres with different processing histories. It is proposed that the degree of radial fibrillar texturing is therefore related to fibre homogeneity. An extrapolation of tensile modulus to that of a perfectly homogeneous fibre results in a value in good agreement with the PBO crystal modulus. This further supports the proposal that the degree of radial fibrillar texturing is related to fibre homogeneity. 相似文献
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Jie Kong Xiaodong Fan Wenqiang Qiao Yunchuan Xie Qinfa Si Yusheng Tang 《Polymer》2005,46(18):7644-7651
The regularity of ‘skin-core’ type of crystallinity distribution within the polyethylene cylindrical specimen crystallized under high pressure was investigated via modulated differential scanning calorimeter (MDSC), wide angle X-ray diffraction meter (WAXD), dynamic mechanical analyzer (DMA) and scanning electron microscope (SEM). The relationship between the gradient of high pressure stress field and the ‘skin-core’ structure of polyethylene was also established. The results indicate that there exists a distinguished difference of crystallinity, morphology and dynamical mechanical properties between skin layer and core region within the cylindrical specimen crystallized under 650 MPa pressure. The measurement data of the non-reversible heat flow of MDSC and WAXD for both skin layer and core region are in accordance with that marked difference. According to the law of stress decay of high pressure stress field and the high pressure crystallization theory of polymers, it was found that the uneven distribution of high pressure stress field, especially, the high pressure decay effect at the edge of plunger and cylindrical channel of the mold is proposed as the principal factor to the formation of the ‘skin-core’ type of crystallinity distribution within the polyethylene cylindrical specimen crystallized under high pressure. 相似文献
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《Journal of the European Ceramic Society》2019,39(15):4911-4920
Thin-walled 3D-customized ceramic components can be used, e.g. for inert and thermal resistant housings as well as special surface structured kiln furniture. For manufacturing such components, deep drawing of ceramic green tapes has been used. The technology has been almost not applied for processing of ceramic green tapes. A new approach was developed to realize a homogenous ceramic particle packing and hence uniform green density within a deep drawn green tape. After debinding and sintering, defect-free model structures with a dense microstructure (density > 99%) were achieved. Within this study, the deep drawing of ceramic green tapes by using a new approach was investigated. The developed approach brings several beneficial properties together, e.g. a reproducible form deviation and more importantly a homogeneous particle distribution allowing homogeneous and dense structures. With this results, the transformation of non-complex and cheap ceramic green tapes to 3D-customized and near-net-shape thin-walled mouldings becomes possible. 相似文献
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Delamination is the most common failure mode in laminated composites due to the reduced strength in the through‐the‐thickness direction. Air‐jet texturing was used to produce bulk and loops in the yarn, which provides more surface contact between the fibers and the resin. The development of core‐and‐effect textured glass yarns and the effect of texturing parameters were presented in the previous article. This article describes the effect of texturing on the mechanical properties including tensile properties, flexure properties, interlaminar shear strength (ILSS) and fracture toughness (Mode I) of glass laminated composites. The composites of plain and twill weave fabrics were developed from both the textured and nontextured yarns. It was observed that the tensile properties decreased and the flexure properties remained unchanged after texturing. However, significant improvement was observed in ILSS and the Mode I fracture toughness of the composites after texturing. The bulkier, loopy structure of the textured yarn provided more surface contact between the fiber and the resin and significantly improved the bonding strength. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers 相似文献
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Effect of degree of crystallographic texture on ferro‐ and piezoelectric properties of Ba0.85Ca0.15TiO3 piezoceramics
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Jan Schultheiß Oliver Clemens Sergey Zhukov Heinz von Seggern Wataru Sakamoto Jurij Koruza 《Journal of the American Ceramic Society》2017,100(5):2098-2107
Crystallographic texturing is a promising approach to reduce the performance gap between randomly oriented polycrystalline piezoelectrics and perfectly oriented single crystals. Here, the influence of the degree of crystallographic texture on the electromechanical properties and their temperature stability of the lead‐free perovskite ferroelectric Ba0.85Ca0.15TiO3 is investigated. Samples with a broad range of (100),(001) crystallographic texture (Lotgering factor 26%‐83%) were prepared by the reactive templated grain growth method. Crystallographic and microstructural analysis have been carried out using X‐ray diffraction and scanning electron microscopy, while the temperature‐dependent electromechanical properties were characterized by dielectric, piezoelectric, polarization, and strain measurements. It was revealed that the total bipolar strain and the coercive field are linearly dependent on the Lotgering factor. The total bipolar strain increased by 80%, whereas the coercive field decreased by 18% due to crystallographic texturing. Likewise, the temperature stability of the electromechanical properties of the samples was found to be dependent on the degree of texture. A sample with a high degree of texture exhibited a Curie temperature of 117°C, which is 21% higher compared to a counterpart with a low degree of texture. This was related to chemical inhomogeneity and a modified internal mechanical stress state. 相似文献
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《Ceramics International》2019,45(15):18222-18228
The properties of ceramics can be improved by controlling the microstructure through texturing ceramics in a strong magnetic field. Fabricating dense boron carbide (B4C) requires high temperature sintering, therefore sintering additives are often used in order to densify B4C ceramics at lower temperatures. However, combined effect of texturing and sintering additives on densification of B4C has not been made clear yet. Here we report the effect of alumina (Al2O3) sintering additive on texturing in a strong magnetic field and densification of B4C. Texturing was performed by rotating superconducting magnet at 12 T during slip casting process. Electron backscatter diffraction (EBSD) was used to observed the texturing projection. {0001} plane is clearly oriented in the plane parallel to rotating magnetic field. In addition, Lotgering factor was also calculated as quantitatively evaluation of texturing degree. Results on densification showed that addition of Al2O3 successfully increased density of B4C sintered by spark plasma sintering (SPS) at 1800oC to 97.8%. Formation of aluminum borate (Al5BO9) as secondary phase was detected by X-Ray diffraction (XRD). It is considered that the generation of Al5BO9 assisted finer densification of B4C ceramic. Textured B4C sintered at 1700oC by SPS without alumina addition exhibited the highest orientation of c-axis. Addition of alumina caused decrease in degree of orientation of c-axis. 相似文献
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采用线性黏弹性模型,模拟计算了平板形状制品残余应力在壁厚方向和流动方向上的分布及其在成型中的变化过程。根据模拟结果,深入讨论了注射成型过程中残余应力的形成机理和演变情况。结果表明:脱模时制品表层有着较大的拉应力,表层以下存在着一个应力低谷,在制品中心区域存在着抛物线形的拉应力分布;残余应力沿壁厚分布的形状在流动方向上基本相同,但是流动末端的应力值稍大于流动入口处。 相似文献