Protein foaming method to prepare Si3N4 foams by using a mixture of egg white protein and whey protein isolate

Structure and properties of Si3N4 foams prepared by using egg white protein or whey protein isolate were compared. Pores of Si3N4 foams prepared by using egg white protein are generally closed, while pores prepared by using whey protein isolate are generally open. However, layered structure is found in the Si3N4 foams prepared by using whey protein isolate. Further, a combinational usage of egg white protein and whey protein isolate was employed to prepare Si3N4 foams. It is indicated that the addition of egg white protein when using whey protein isolate as foaming agent can avoid the formation of layered structure in the product. However, the size and number of windows on the walls decrease with the addition of egg white protein. Moreover, it is indicated that the combinational usage of egg white protein and whey protein isolate has certain advantage over using either of them especially when solid content is high.