高性能陶瓷材料的离心成型法制备及性能研究

发布时间：2018-04-17 09:09

本文选题：Al_2O_3 + Al_2O_3/ZrO_2　；参考：《东北大学》2010年博士论文

【摘要】：氧化铝陶瓷具有强度高、耐高温、耐腐蚀、耐磨损及良好的介电性能等特性,在电子、冶金、机械、交通、能源、航空航天和生物领域得到广泛的应用。如何改进Al2O3粉体及其复合陶瓷的制备工艺,以改善材料的微观结构,提高其性能和可靠性,成为目前陶瓷研究领域的重点。离心成型作为胶态成型的一种,具有坯体密度高,均匀性好,成型缺陷少的优点,因而是制备高性能陶瓷及其复合材料的先进方法之一。本文系统研究了采用离心成型法制备Al2O3陶瓷、Al2O3-ZrO2陶瓷基复合材料、以及Al2O3/Ni梯度材料的工艺过程以及这些材料的微观组织和力学性能。采用硫酸铝铵热分解法制备了颗粒尺寸为60～100nm的高纯α-Al2O3纳米粉体,并用离心成型方法制备了高性能Al2O3陶瓷材料。研究表明,分散剂添加量、pH值、固相含量对浆料性能有显著的影响；采用流动性好、固相含量高、稳定性好的浆料以及合适的离心成型工艺,制备出密度高,均匀性好的陶瓷坯体,并通过后续的真空烧结获得了显微组织均匀细小,力学性能优异的Al2O3陶瓷材料。实验结果表明：当分散剂聚羧酸胺的添加量为1wt%,浆料pH为11,固相含量为38vol%时浆料具有良好的流动性和稳定性,获得的坯体相对密度达到52.36%；试样在空气中1200℃温度下经120min预烧,然后在1550℃经150min真空烧结后,得到呈半透明状的氧化铝陶瓷,其烧结密度、强度、硬度、断裂韧性分别为3.98g/cm、712 MPa、19.4GPa、3.92MPa·m1/2。1500℃和1550℃下真空烧结的样品平均晶粒尺寸均小于5μm。采用离心成型方法制备了Al2O3-5vol%ZrO2复合材料,并对其坯体密度、Al2O3和ZrO2分布、烧结密度,以及显微组织和力学性能进行了系统的实验研究。实验结果表明,通过采用合适的分散剂含量和固相含量,可以获得流动性和稳定性良好的浆料,避免离心成型过程中发生Al2O3和ZrO2因比重不同产生的相分离。压坯密度随固相含量的增加而有所增大,并且不同固相含量试样的底部区域压坯密度稍高于其它部位；除固相含量30%试样底部区域外,所有试样的烧结密度沿坯体高度无明显变化,氧化铝、氧化锆分布沿高度方向几乎不发生变化；经1450℃烧结得到了显微组织细小均匀、Al2O3晶粒小于2μm、性能优良的Al2O3/5vol%ZrO2复合材料,其抗弯强度为710 MPa,显著高于干式成型法制备的复合材料的强度(620 MPa).Al2O3-5vol%ZrO2(?)内离心成型和干压成型试样性能对比发现,压坏密度提高了5%,烧结温度降了50℃,抗弯强度得到显著提高。采用离心成型方法制备了组分呈连续梯度分布的Al2O3/Ni功能梯度材料。通过调制复合粉末浆料的特性,可调控离心成型过程中Al2O3和Ni因比重和颗粒尺寸不同产生的相分离程度,从而获得所需的Al2O3和Ni的梯度分布。在实验的基础上优化了浆料中粘结剂和固相的含量以及浆料的球磨时间。对梯度复合材料试样的气孔率,三点抗折强度、硬度等性能及其影响因素进行了研究。实验结果表明：粘结剂(聚乙二醇)含量为2wt%、固相含量为63vol%、球磨时间为36小时的条件下制备的浆料,适合用于离心成型方法制备Al2O3/Ni梯度材料。采用离心成型制备出气孔率为0.4%,显微组织和硬度均呈连续梯度分布、力学性能优良的Al2O3/Ni梯度材料。通过调整固相含量和粘结剂含量,可调控Al2O3/Ni梯度材料的成分梯度,对组织结构进行设计和控制。采用改进Stober法制备出符合胶晶模板要求的单分散SiO2微球,并发现在反应过程中始终保持高氨水浓度更有利于单分散SiO2微球的生成。当浓度高于0.5 vol%时,SiO2微球悬浮液可在玻璃基板上形成有序度较高的二维胶晶模板。离心沉降法可快速制备出大尺寸蛋白结构SiO2光子晶体。SiO2光子晶体为面心立方结构,结构内的主要缺陷为溶剂挥发所形成的裂纹以及堆垛层错。向三维有序SiO2胶晶模板的孔隙内填充Sb2S3,而后通过HF溶液腐蚀掉SiO2胶晶模板,进而制备出反蛋白结构Sb2S3光子晶体。
[Abstract]:Alumina ceramics with high strength, high temperature resistance, corrosion resistance, abrasion resistance and good dielectric properties, in electronics, metallurgy, machinery, transportation, energy, widely used in aerospace field and biology. How to improve the preparation process of Al2O3 powders and ceramic composites, in order to improve the microstructure of the material. To improve its performance and reliability, has become the focus of research in the field of ceramic. Centrifugal molding as a colloidal molding, with blank high density, good uniformity, the advantages of forming less defects, so it is one of the advanced methods of preparation of high performance ceramics and composite materials. This paper systematically studies the preparation of Al2O3 ceramic by centrifugal molding method, Al2O3-ZrO2 ceramic matrix composites, and the process of Al2O3/Ni gradient material and microstructure and mechanical properties of these materials.
The particle size is 60 ~ 100nm high purity -Al2O3 nano powders were prepared by thermal decomposition of ammonium aluminum sulfate, high performance Al2O3 ceramic materials were prepared by centrifugal casting method and system. The results show that the addition of dispersant, pH value, solid content has a significant effect on the properties of the slurry with good fluidity; high solid content, good stability and centrifugal slurry suitable extruding process, preparation of high density, uniform ceramic body is good, and the microstructure is fine and uniform by subsequent vacuum sintering, Al2O3 ceramic material with excellent mechanical properties. The experimental results show that: when the addition amount of dispersant polycarboxylic acid amine 1wt%, pH slurry is 11, solid content of 38vol% slurry with good fluidity and stability, the body obtained relative density reached 52.36%; the sample at a temperature of 1200 DEG C in the air by 120min pre sintering, then at 1550 DEG C by 150min vacuum After sintering, a semi transparent alumina ceramic was obtained. The sintered density, strength, hardness and fracture toughness were 3.98g/cm, 712 MPa, 19.4GPa, 3.92MPa, m1/2.1500 and 1550 degrees, respectively. The average grain size of vacuum sintered samples was less than 5 m..
Al2O3-5vol%ZrO2 composites were prepared by centrifugal casting method, and the body density, Al2O3 and ZrO2 distribution, and sintered density, microstructure and mechanical properties were studied systematically. The experimental results show that the dispersant content and solid content through the use of appropriate size, can obtain good fluidity and stability. Avoid centrifugal forming in the process of Al2O3 and ZrO2 due to phase separation produced in different proportions. Increasing the compact density increased with solid content and increase the bottom area and different solid content samples of compact density is slightly higher than the other parts; in addition to the solid content of 30% samples at the bottom of the region, the sintering density of all specimens along the body height significant changes, alumina, zirconia distribution along the height direction has little change; the 1450 C sintered microstructure is fine and uniform, Al2O3 small grain in 2 mu m. Al2O3/5vol%ZrO2 composite material is excellent, the flexural strength was 710 MPa, significantly higher than the strength of the composites prepared by dry molding (620 MPa).Al2O3-5vol%ZrO2 (?) in centrifugal molding and dry pressing molding contrast sample performance, crush density is increased by 5%, the sintering temperature drop of 50 degrees, the flexural strength significantly to improve.
A group of Al2O3/Ni FGM continuous gradient distribution was prepared by centrifugal casting method. Through the modulation of composite powder slurry, adjustable centrifugal molding process in Al2O3 and Ni due to the degree of phase separation and produce the proportion of different particle sizes, gradient distribution to obtain the required Al2O3 and Ni. In the optimization experiment on the basis of the binder and solid slurry in the slurry content and milling time. The sample porosity gradient composite rate, three point flexural strength, hardness and impact factors were studied. The experimental results show that the bonding agent (polyethylene glycol) content is 2wt%, the solid content was 63vol%, milling time is 36 hours the conditions for the preparation of slurry, suitable for centrifugal casting method to prepare Al2O3/Ni gradient material prepared by centrifugal casting. The porosity was 0.4%, the microstructure and hardness were continuous gradient points The Al2O3/Ni gradient material with excellent mechanical properties is able to control the composition gradient of Al2O3/Ni gradient material and design and control the microstructure by adjusting the solid content and binder content.
The improved Stober was prepared with monodisperse SiO2 microspheres colloidal crystal template requirements, and found in the reaction process, and always maintain a high concentration of ammonia is more conducive to the formation of monodisperse SiO2 microspheres. When the concentration is higher than 0.5 vol%, SiO2 microspheres suspension can form two-dimensional colloidal crystal template with high orientation in centrifugal glass substrate. Settlement method can be used for fast preparation of large size protein structure of SiO2 photonic crystal photonic crystal.SiO2 face centered cubic structure, the main defect in structure formed by the evaporation of solvent crack and stacking fault. To fill the Sb2S3 pore 3D ordered colloidal crystal template of SiO2, and then through the HF solution etching of SiO2 colloidal crystal template then, prepared the anti protein structure of Sb2S3 photonic crystal.

【学位授予单位】：东北大学
【学位级别】：博士
【学位授予年份】：2010
【分类号】：TQ174.62

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