蛋白发泡法制备泡沫陶瓷固化工艺研究

Study on the Consolidation Process of Protein Foaming in the Preparation of Ceramic Foams

选用蛋清蛋白作为发泡剂,采用蛋白发泡法制备了高孔隙率的泡沫氮化硅陶瓷.设计了三种不同固化工艺:常压固化、恒压固化和高压固化,固化气压依次升高,研究了固化气压对泡沫陶瓷开孔率、孔隙形貌和孔径分布的影响.其中,恒压固化制品的平均孔径和开孔率最高,分别为210μm和78.6%,且孔径分布比较均匀,常压固化次之,高压固化制品开孔率和平均孔径最低.常压和恒压固化制品为椭球形孔洞,有一定的排列取向,而高压固化制品多为规则的球形孔.随着固化气压的升高,制品孔壁厚度增加,高压固化制品的孔壁厚度最高,其压缩强度接近50 MPa.

High porosity Si3N4 ceramic foams were fabricated by protein foaming method using egg white protein as foam agents. Atmosphere-, constant- and high-pressure consolidation processes were tested to prepare ceramic foams. The effects of air pressure on cellular structure, open porosity and pore size distribution of the as-prepared ceramic foams were investigated. The results showed that ceramic foams with average pore size and porosity of 210 μm and 78.6% was obtained by constant-pressure consolidation, which are the highest values among all the three groups. Moreover, SEM reveals that ceramic foams with uniformly ellipsoidal pores are produced by atmosphere- and constant-pressure consolidation processes, while ceramic foams with regular sphere pores are produced by high-pressure consolidation. The walls＇ thickness of the pores increase with the increase of air pressure during consolidation process. As a result, the high-pressure consolidation process yields the highest compressive strength （nearly 50 MPa） of ceramic foams.