轻质高强泡沫陶瓷材料是一种重要的结构材料和功能材料，具有轻量化特点和独特的孔结构，在越来越多的工程技术领域发挥重要作用。低成本制备高气孔率且孔结构可调控的新型泡沫材料以满足更多场合应用成为研究热点。本文采用成本低廉、工艺简便易行、普适性强的颗粒稳定泡沫技术，选用十二烷基硫酸钠(Sodium dodecyl sulfate，简称SDS)作为颗粒疏水修饰剂制备超稳定的泡沫浆料，通过成分和微观结构优化制备力学性能优异的超轻泡沫陶瓷。主要创新结果如下：选用长链表面活性剂SDS同时作为发泡剂及颗粒疏水化修饰剂，制备得到超稳定的Al2O3、ZrO2泡沫浆料。研究了SDS在陶瓷颗粒表面的吸附特性，阐明了颗粒表面修饰改性机制及泡沫稳定影响因素。完善和发展了颗粒稳定泡沫机理：在国际上首次揭示了颗粒zeta电位对泡沫稳定性的影响规律，论证并解释了以长链表面活性剂修饰粉体表面在等电点制备稳定的颗粒均匀组装泡沫的可行性。基于超稳定泡沫浆料，首次制备了气孔率高达99%的Al2O3、ZrO2泡沫陶瓷，并提出了三种增强泡沫坯体的措施。系统地研究了泡沫陶瓷性能的调控方法，以及SDS添加量、固相含量、烧结温度等因素的影响机制。揭示了泡沫陶瓷的孔形貌、力学性能与气孔率的关系。采用铝溶胶作为原料，通过调控固相含量成功制备了：(1)具有纳米尺度孔壁，气孔率和比表面积可与气凝胶媲美的泡沫材料；(2)具有多级孔结构、力学性能优异的Al2O3泡沫陶瓷。系统研究了烧结过程中孔结构的演变过程及该体系材料的保温性能和吸附能力，并阐明了这种多级孔轻质陶瓷材料力学性能的强化机制。以微米级铝粉为原料颗粒，利用其在烧结过程中的原位空心化现象制备出孔壁由微米级空心球组装而成的新型Al2O3基陶瓷泡沫材料，大幅度地提升了泡沫材料的强度，同时首次实现了泡沫陶瓷材料的烧结不收缩。系统研究并解释了Al核/Al2O3壳层结构在热氧化过程中发生的空心化过程及机理，阐明了这种新材料力学性能大幅度改善以及烧结无收缩的机理。为实现复杂形状、精细结构泡沫陶瓷材料的制备，研究并优化了泡沫浆料流变特性，创新性地结合3D打印直写技术制备了复杂形状泡沫陶瓷材料。此外，还研究了具有光固化特性的陶瓷颗粒稳定泡沫浆料/乳液的制备，探讨了颗粒疏水性和水油两相比例对颗粒稳定乳液相结构的影响规律，为光固化打印3D轻质泡沫陶瓷奠定了理论基础与数据支撑。
Ceramic foams which are well known as important structural and functional materials due to their light weight and unique pore structure are playing indispensable role in more and more engineering and technology fields. Therefore, it has been a research hotspot to prepare new foam materials with low cost, high porosity and adjustable pore structure to meet more application demand. In this paper, stable colloidal foams has been prepared via particle-stabilized foams with long chain surfactant sodium dodecyl sulfate (short for SDS), based on which we have further fabricated a variety of novel ceramic foam materials with high porosity level and significantly improved mechanical properties by optimizing composition and microstructure. The main innovative results are listed as follows:SDS has been employed as both foaming agent and hydrophobic modifier of ceramic powders to prepare ultrastable alumina and zirconia foams. The adsorption ability of SDS on ceramic particles, hydrophobicity of modified particles, and foam stability have been studied. The foam stabilization mechanism has been further developed, which has revealed the influence of particle zeta potential on foam stability and the feasibility of preparing stable foams with uniform wall by modifying powder with long chain surfactant at the isoelectric point (IEP).Alumina and zirconia ceramic foams with porosity up to 99% have been prepared based on the obtained stable foams. The strength enhancement of ultraligh dried foams has been explored by three kinds of approaches. The effects of SDS concentration, solid loading and sintering temperature on performance of ceramic foams have been systematically investigated. The pore morphology and mechanical properties affected by porosity level have also been studied. Boehmite has been employed as starting material for the first time to successfully fabricate: (1) aerogel-like foams with nano-scale thickness wall and ultrahigh specific surface area that are comparable to aerogel, (2) ceramic foams with hierarchical pore structure and excellent mechanical strength. The evolution of pore structure during sintering has been researched. The thermal insulation performance and adsorption capacity have been studied, and the strengthening mechanism has been clarified.A new kind of alumina ceramic foams and alumina/aluminum composite foams with hollow structured wall have been prepared via the in-situ hollowing of micron-sized metal aluminum powder, based on the Kirkendall effect of aluminum powder during sintering. The fabricaition of foam material with significantly increased strength and zero-sintering shrinkage has been realized for the first time. The hollowing process of Al core/alumina shell structure during thermal oxidation has been studied and explained, and the mechanism of significantly impoved strength and zero-sintering shrinkage has been clarified. In order to achieve the fabrication of ceramic foam materials with complex geometries and fine structures, the rheological properties and printability of colloidal foams have been studied and optimized. The 3D lightweight ceramics have been printed by direct writing foams, which allow for the shape design lightweight ceramic foam materials. In addition, novel ceramic particle stabilized foam/emulsion with photocurable properties have been proposed and prepared. The influence of particle hydrophobicity and water/oil ratio on the phase structure of particle stabilized emulsion has been investigated, which potentially provides the theoretical foundation and data support for 3D printing lightweight ceramics via stereolithography apparatus (SLA) printing technique.
