1、硕士学位论文Al-Si/Al2O3-SiC 核壳结构颗粒的制备与性能表征THE SYNTHESIS AND PROPERTIESCHARACTERIZATION OF Al-Si/Al2O3-SiCCORE-SHELL MICRO-PARTICLES闫以秀2013 年 07 月国内图书分类号：TB35 学校代码：10213国际图书分类号：620.17工学硕士学位论文Al-Si/Al2O3-SiC 核壳结构颗粒的制备与性能表征硕 士 研 究 生：闫以秀0 师：何飞 副教授 申 请 学 位：工学硕士0 科：材料学 所 在 单 位：航天学院答 辩 日 期：2013 年 07 月授予学位单位：哈尔滨工
2、业大学Classified Index: TB35U.D.C: 620.172Dissertation for the Master Degree in EngineeringTHE SYNTHESIS AND PROPERTIESCHARACTERIZATION OF Al-Si/Al2O3-SiCCORE-SHELL MICRO-PARTICLESCandidate： Yan YixiuSupervisor： A.P. He FeiAcademic Degree Applied for： Master of EngineeringSpeciality： Material ScienceAf
3、filiation： School of AstronauticsDate of Defence： July, 2013Degree-Conferring-Institution： Harbin Institute of Technology哈尔滨工业大学工学硕士学位论文0 要 相变材料具有储能控温的作用。相较于其他相变材料，Al-Si 合金储能密度较大、高温稳定性强、过冷度小、 导热系数大、价格便宜、材料来源丰富，是一类很有应用前景的相变储能材料。但是，液态 Al-Si 合金具有一定的流动性和很强的腐蚀性，一般的金属及合金等容器很难使其在高温下长期稳定工作。因此，实现 Al-Si 合金熔体在
4、高温状态下的有效封装是 实现该材料实用化的必要手段。本论文在 Al2O3 对 Al-Si 合金有效微封装制备 Al-Si/Al2O3 核壳结 构粒子的基础上，通过在 Al 2O3 壳层内引入高热导率且具有高温惰性的 SiC 颗粒，以提高壳层的热导率，使 Al-Si 合金相变材料的蓄放 热速度增大，从而改善其储能控温的效果。本论文通过大量实验和 Zeta 电位、 TEM 等测试手段研究分析了 SiC 纳米粉的分散和改性方法，探讨 Al 2O3-SiC 复合壳层的制备原理。结果表明，经KH550 分散、氧化铝溶胶包覆的 SiC 颗粒表面仅仅附着有少量的溶胶颗粒，并没有将 SiC 颗粒全部包裹在溶胶
5、里。采用十二 烷 基苯磺酸钠(Sodium dodecylbenzene sulfonate, SDBS)分散的 SiC 颗粒表面基本全部被晶 须状溶胶颗粒包 裹。这是因为经 SDBS 分散后，SiC 颗粒表面带负电，易与表面带正电的Al 2O3 溶胶 结合，形成 AlOSi 的化学键，有利于在其表面继续接枝化合物， 获 得 分 散 性 较 好 、 包 覆 效 率 高 的 改 性 SiC 纳 米 粉 ， 从 而 成 功 制 备 出 Al-Si/Al2O3-SiC 核壳粒子。研究中分析了烧结温度对 Al-Si/Al 2O3-SiC 核壳粒子形貌的影响，并利用XRD 分析方法对不同温度下的烧结产物
6、进行了物相分析。结果表明，随着热处理温度的提高，壳层逐渐变 得致密， 经 1200烧结后， Al-Si/Al2O3-SiC 核 壳 粒 子 表 面 致 密 ， 包 覆 完 整 ， 壳 层 的 成 分 主 要 为 -Al 2O3 ， 并 含 有 少 量 的SiC。但是，由于加入的 SiC 纳米粉含量较少以及改性 SiC 纳米粉不可避免地出现团聚现象，这导致 SiC 纳米粉在核壳粒子的壳 层中分散不均匀。利用差式扫描量热(DSC)分析方法对制备的 Al-Si/Al2O3-SiC 的相变潜热进 行了测试分析， 实验结果与理 论计算的数值有一定的偏差。这主要是由于 Al-Si/Al 2O3-SiC 核
7、壳粒子不可避免地会发生壳层的破 损，从而导致 Al-Si 熔体在 高温下发生泄漏并产生氧化。另外，Al-Si 合金在高温热处理后会发生成分偏 析，造成 Si 的富集，使得 Al-Si 合金的组分不均匀。 这两个原因均会造成核壳粒子相变潜热的降低。实验利用热导率测试手段分析了 SiC 的加入对核壳- I -哈尔滨工业大学工学硕士学位论文粒子热导率的影响，同时对核壳粒子的抗热渗漏性进行了研究分析。结果表明 核壳粒子的热导率随 SiC 含量的增加而增加。宏观颗粒抗热渗漏性对比实验 结果表明，经包裹后的核壳颗粒具有明显的抗热渗漏性。关键词：Al-Si/Al 2O3-SiC；核壳结构；储能控温；相变潜热
8、；微封装- II -哈尔滨工业大学工学硕士学位论文AbstractPhase change materials has the function of storing energy and controlling temperature. Compared to other phase change materials, Al -Si alloy has the property of high density of energy storage, high thermal stability, small undercooling, high thermal conductivity, ri
9、ch material sources, low manufacturing cost. It is a kind of promising phase change and energy storage materials. However, its high causticity and incompatibility are primary problems obstructing its application, when Al-Si alloy changes from solid phase to liquid at high temperatures. Therefore, it
10、 is very significant for the practical applications to achieve the effective encapsulation of Al-Si melt under high temperature conditions. Based on the micro-encapsulation technology of Al-Si/Al2O3 core-shell structureparticles, SiC particles with high inertness and thermal conductivity were introd
11、uced into the Al2O3 shell in order to improve its thermal conductivity whichis a useful method to improve the heat storage speed of Al-Si alloy so as to enhance the effect of energy storage.Some of experiments and analysis methods, such as Zeta potential measurement, transmission electron microscope
12、(TEM), were adopted to research the dispersion and modification of SiC nano-meter powders in order to analyze the preparation mechanism of Al2O3-SiC composite shell. When SiC powders weredispersed by KH550, only a small amount of sol particles were adhered on there surface. After dispersed by sodium
13、 dodecyl benzene sulfonate (SDBS), however, SiC powders were wrapped by the alumina sol particles on the surface. The reason is that the surface of SiC powder dispersed by SDBS is negatively charged, which is benefit to attract positively charged Al2O3 sols to form AlOSi bonds. Thus, itis more effec
14、tive to to graft compounds on the surface of SiC powders so as to synthesize the modified SiC nano-meter powders.The morphology and phase analysis of Al-Si/Al2O3-SiC core-shell particles atdifferent heat treatment temperatures were performed by means of scanning electron microscopy (SEM) and X-ray d
15、iffraction (XRD). With the increasing of sintering temperature, the shell becomes much denser. After sintering at 1200, Al-Si/Al2O3-SiC core-shell structure materials possess on integrate dense surface.- III -哈尔滨工业大学工学硕士学位论文The components of the shell contain -Al2O3 and a small amount of SiC. Becaus
16、ethe amount of the SiC nanometer powders are small and the modified SiC nano-meter powders are inevitably followed with agglomeration, it can be ascertained that SiC particles dispersed in the shell are not uniform.The latent heat of the Al-Si/Al2O3-SiC core-shell particles were obtained bymeans of
17、differential scanning calorimetry (DSC). The results showed that there is a certain deviation between the experimental data and theoretical values. On one hand, it is attributed to the breakage of the shell during the process of heat treatment which leads to the leakage and oxidation of Al-Si alloy.
18、 On the other hand, the segregation and enrichment of Si elements results in componential non-uniform. The latent heat of Al-Si/Al2O3-SiC core-shell particles is reduced based on thesetwo reasons. The thermal conductivitiy of the core-shell particles with different adding amounts of SiC particles we
19、re characterized. The results revealed that as SiC contents increases, the value of thermal conductivity increase. The contrast experiment on thermal leakage resistance bewteen Al-Si/Al2O3-SiC core-shellparticles and original Al-Si alloy particles showed that core-shell particles are provided with good thermal leakage resistance performance.Keyword: Al-Si/Al2O3-SiC; core-shell structure; energy storage and temperatureControlling; latent heat; micro-encapsulation- IV -
