Studies On Preparation Si₃N₄ Ceramic Foam By Protein Foaming Process And Its Thermal Property

Si₃N₄ ceramic foam is a new ceramic material and can bear high temperature. It is used in the manufacturing industry, aerospace industry and other fields, so it has broad application prospect. This paper was to improve and systematically research protein foaming method based on the samples of closed-pore Si₃N₄ ceramic foams with high porosity and uniform distributed pore. Besides, this paper established a 3D model, which is closer to the real foamed material structure. Based on this foundation, the paper had studied the thermal property of Si₃N₄ ceramic foams by finite element simulation. The main research contents are as follows:First of all, this paper researched and made defect analysis on the principle of protein foaming method. By changing the foaming agent, improving the curing process and changing mixing direction, the protein foaming method to fabricate Si₃N₄ ceramic foams was improved. Orthogonal testing method was used to systematically analyze the effects of the addition quantity of foaming agent, addition quantity of sucrose, and foaming time on the porosity and density of Si₃N₄ ceramic foams. Based on these situations, the optimal conditions of molding were obtained. Then the samples of Si₃N₄ ceramic foams with uniform distributed pore were prepared;Secondly, 2D random round model, 3D random sphere model, 2D Voronoi model and 3D Voronoi model with adjustable pore wall structure of the foam material were established. In addition, 3D sphere model with adjustable porosity and pore size range and 3D Voronoi model with adjustable minimum wall thickness were generated by utilizing the Matlab program. Therefore, the structure of model that is more suitable for foam material was obtained.Finally, testing experiment of thermal conductivity on Si₃N₄ ceramic foams samples with different porosity was conducted in order to analyze the relation between porosity and thermal property. Si₃N₄ foam models with different porosity were generated by employing 3D sphere model. Besides, the finite element simulation of thermal property was implemented by Workbench. The results of simulation were consistent with the experiment results, so it can be used to guide production practice.