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heterogeneous nucleation是什么意思,heterogeneous nucleation的意思翻译、用法、同义词、例句

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常用词典

  • [晶体] 异相成核

  • 例句

  • Stirring of substrates may accelerate the heterogeneous nucleation and growth of the melt.

    衬底的搅拌可加速熔体的非自发成核和长大。

  • Effect of melting temperatures on heterogeneous nucleation of polypropylene (PP) nucleated with different nucleating agents was investigated by DSC.

    用DSC研究了熔融温度对不同类型成核剂成核PP的异相成核作用的稳定性的影响。

  • Continuous nucleation model was used to describe heterogeneous nucleation of the liquid metal.

    在模拟过程中,采用连续形核的方法处理液态金属的异质形核现象。

  • The results show:1)Formation scaling is formed in the repeated heterogeneous phase nucleation and crystal growth. The crystal can grow both in pores and at throats.

    研究结果表明:1油层结垢是在多次的异相成核—晶体生长过程形成的,晶体生长在孔隙中和喉道处均可发生;

  • During the treatment process of flue gas, heavy metal was concentrated in fly ash by the way of homogeneous nucleation and heterogeneous deposition.

    在尾气处理过程中,重金属以均匀核化、异相沉积等方式从烟气浓缩到飞灰中。

  • The coupling analyses by DSC and polarized light microscopy proved the nucleation in the multiple crystallization was heterogeneous.

    DSC和偏光显微联用分析发现,所有峰对应的结晶都是异相成核。

  • It was found in the experiment that the glass fiber (GF) has the function of heterogeneous nucleation for polypropylene (PP) and improves the crystalline morphology of PP.

    试验表明,玻璃纤维(GF)对聚丙烯(PP)起异相成核作用,改变聚丙烯的结晶形态;

  • Continuous nucleation model is applied to describe heterogeneous nucleation in liquid metal.

    采用连续形核模型来描述液相中的自发形核。

  • Based on the cellular automata technique, the heterogeneous nucleation model, dendrite growth model and random nucleation model are used to simulate the formation of equiaxed and columnar dendrite.

    通过引入异质形核模型、枝晶生长模型、几率形核基底模型,借鉴单元自动生长机制,仿真了等轴晶、柱状晶组织形成的过程。

  • A continuous nucleation model was used to deal with the heterogeneous nucleation of a liquid metal.

    采用连续形核的方法处理液态金属的异质形核现象。

  • A small quantity of fly ash can play a role in the heterogeneous nucleation, but increasing the filled quantity can change the crystallization form of PP.

    少量粉煤灰可起到异相成核的作用,填充量的增加会改变PP的结晶形态;

  • It was concluded that the synthesis process of the LDHs films was heterogeneous nucleation.

    研究认为,该薄膜的生长是一个异相成核的过程。

  • The results showed the addition of zeolite resulted in heterogeneous nucleation crystallization of PP, and improved the crystallinity of PP;

    结果表明,沸石的引入使PP产生了异相成核结晶,结晶度提高;沸石质量分数为3%时,复合材料体系结晶较为完善;

  • Heterogeneous nucleation may take place at significantly lower supersaturations than homogeneous nucleation.

    多相成核能在比均相成核低很多的过饱和状态下发生。

  • 专业解析

    异质形核(Heterogeneous Nucleation) 是指新相(如晶体、液滴等)在凝固、结晶或相变过程中,优先依附于系统中已存在的外来界面(如容器壁、杂质颗粒、气泡表面等)上成核的现象。与均质形核(在均匀母相内部自发成核)相比,异质形核所需的能量壁垒更低,因此在自然界和工业过程中更为常见。

    核心机制与特点:

    1. 能量壁垒降低

      异质形核的核心优势在于降低了临界形核功。根据经典形核理论,新相在基底表面成核时,其临界形核能 (Delta G^) 可表示为: $$ Delta G^ = Delta G{text{hom}}^ cdot f(theta) $$ 其中 (Delta G{text{hom}}^) 是均质形核能垒,(f(theta) = frac{(2 + cos theta)(1 - cos theta)}{4}),(theta) 为新相与基底的接触角。当 (theta < 180^circ) 时,(f(theta) < 1),表明异质形核更易发生。

    2. 基底的关键作用

      基底表面的化学成分、晶体结构及粗糙度直接影响形核效率。若基底与新相的晶格匹配度高(共格界面),或表面能较低,可显著促进形核。例如,金属凝固中常用钛、锆等添加剂作为异质形核剂,因其晶格常数与金属晶体接近。

    3. 广泛存在的现象

      • 冶金工业:铸件中加入形核剂(如Al-Ti-B细化铝晶粒),改善材料机械性能。
      • 大气科学:云中水滴在尘埃颗粒上异质形核,形成降雨或降雪。
      • 生物矿化:骨骼、贝壳的碳酸钙结晶以有机基质为基底定向生长。

    理论公式推导(以凝固为例):

    临界形核半径 (r^) 和形核功 (Delta G^) 的表达式为: $$ r^ = -frac{2 gamma_{text{SL}}}{Delta G_v}, quad Delta G^ = frac{16 pi gamma_{text{SL}}}{3 (Delta Gv)} cdot f(theta) $$ 其中 (gamma{text{SL}}) 为固-液界面能,(Delta Gv) 为单位体积相变自由能差。接触角 (theta) 满足杨氏方程:(gamma{text{LV}} cos theta = gamma{text{SV}} - gamma{text{SL}})((gamma{text{LV}})、(gamma{text{SV}}) 分别为液-气、固-气界面能)。


    权威参考文献来源:

    1. Porter, D. A., & Easterling, K. E. Phase Transformations in Metals and Alloys. CRC Press. (形核理论经典教材)
    2. Callister, W. D., & Rethwisch, D. G. Materials Science and Engineering: An Introduction. Wiley. (工业应用案例)
    3. Kashchiev, D. Nucleation: Basic Theory with Applications. Butterworth-Heinemann. (接触角与能量分析)
    4. Pruppacher, H. R., & Klett, J. D. Microphysics of Clouds and Precipitation. Springer. (大气科学中的异质形核)
    5. Meldrum, F. C., & Cölfen, H. Controlling Mineral Morphologies and Structures in Biological and Synthetic Systems. Chemical Reviews. (生物矿化机制)

    网络扩展资料

    heterogeneous nucleation(异相成核)是材料科学和物理化学中的重要概念,指物质在相变过程中,晶核的形成依赖于外来杂质或界面作用的现象。以下是详细解释:

    1.定义与机制

    异相成核是指分子或原子在杂质表面、界面或预先存在的晶种上形成晶核的过程。与均质成核(homogeneous nucleation)不同,异相成核不需要在纯物质内部自发形成晶核,而是借助外部媒介降低能量壁垒,使相变更容易发生。

    2.关键特点

    3.与均质成核的对比

    特征 异相成核 均质成核
    成核位置 杂质或界面 纯物质内部
    能量壁垒 较低 较高
    常见场景 自然水体结冰、合金凝固 超纯液体过冷/过热状态

    4.应用实例

    5.词源与扩展

    如需进一步了解具体领域(如材料科学或气象学)中的应用,可参考相关学术文献或专业教材。

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