1.2 sol-gel method: sol-gel method is mainly used to prepare microporous ceramic materials with nano pore size. Using sol gel technology to prepare foam material, the viscosity of the system increases rapidly in the process of sol to gel transformation, thus stabilizing the bubbles produced in the early stage, which is conducive to foaming. Compared with other processes, the technology has its unique characteristics, and it can also prepare foam ceramic thin films with nano pore size and uniform pore size distribution. Now it is becoming the most active research field in inorganic film preparation process.

1.3 adding pore forming agent method: by adding pore forming agent in ceramic batching, using pore forming agent to occupy a certain space in the green body, and then sintering, pore forming agent leaving the substrate and forming pores to prepare foam ceramics. The shape and size of pore forming agent determine the shape and size of the pores. The main molding methods are molding, extrusion, isostatic pressing, rolling, injection and slurry pouring. Materials with complex shapes and different pore structures can be prepared by this method, but the uniformity of pore distribution is poor.

1.4 organic precursor impregnation method: the ideal preparation method of foam ceramics is the organic precursor impregnation method, and its technological process is shown in the diagram. The foam ceramic prepared by this method has been widely applied in many fields, and has achieved obvious results. Further control of slurry performance, proper optimization of inorganic binder system and strict control of slurry impregnation can improve the performance of foam ceramic products. Ceramic powders, solvents and additives > preparation of organic foams: > pretreatment; = pretreatment > = > > immersion > > removal of excess slurry > > dry > > removal of organic foam > > sintering; however, organic precursor impregnation process has an obvious defect: pore structure of products, especially pore size, depends on pore structure and pore size of selected organic foams. The mesh size of the selected organic foams is limited, which restricts the pore size and structure of the foamed ceramic materials. Zhu Xinwen and other three dimensional reticulated organic foams were used as carriers. A high porosity and almost no hole mesh was prepared by impregnation process. The pore edge of the preform is loose and porous, which solves this problem well.