Wet Green‐State Joining of Alumina Ceramics Without Paste

A new technique for the green‐state joining of alumina ceramics without paste has been developed. Wet alumina green body, gelcast by PIBM (a copolymer of isobutylene and maleic anhydride) gel system, is used as a parent green body. The joining process involves integrating two wet green bodies in a gelling state, followed by drying and sintering. For example, wet green bodies after aging 10 h were joined, and the joint region of the dried and sintered sample exhibited a homogeneous microstructure without defects or an interlayer. The flexural strength of the joined sample (468.5 ± 62.9 MPa) was nearly equivalent to that of a monolithic sample (470.6 ± 27.4 MPa). The joining mechanism was discussed on the basis of interaction among PIBM molecular chains. The proposed joining technique is simple and promising for producing advanced ceramics with large sizes and/or complicated shapes.