Progress of Spontaneous Coagulation Casting of Ceramic Slurries Based on Hydrophobic Interaction

Spontaneous coagulation casting (SCC) is a novel in-situ ceramic forming method, not only universal for various ceramics but also working well at room temperature in air.Here presents the finding of SCC, involving an anion dispersant which acts as both dispersing and coagulating agent.Then, the difference between SCC and other in-situ coagulation methods in principle was elucidated.In SCC, particles participate in the formation of organic network which originates from hydrophobic interaction and hydrogen bonding among the dispersant molecular chains.The ceramic gel formed by SCC is a physical gel and possesses low density which is conducive to water transportation and stress relaxation during drying.In contrast, the one by conventional gelcasting is a chemical gel in which particles are fixed by a dense organic network.Based on the hydrophobic interaction, this review focuses on the design and synthesis of a series of SCC agents to meet the demand of forming dense and porous ceramics from particles with different sizes.That is, an anion dispersant is hydrophobically modified by a surfactant with a short or long chain.The obtained two agents are used for preparation of dense and porous ceramics, respectively.Progress of key technologies in this area including ceramic joining without interface, construction of grain orientation, drying, preparation of dense ceramics and porous ceramics, by SCC is summarized.Typically, alumina disc with a diameter up to 1010 nm and alumina parts with complicated shape such as dome and guide are shown.Future development of SCC is 无 机 材 料 学 报 第 37 卷 also proposed to enable SCC tobe a more universal forming technology for advanced ceramics with a large and/or complicated dimension.