Adhesive Joining of Metal to Metal and Metal to Ceramic by Ceramic Precursor Route

摘要

Inorganic ceramic adhesives (geopolymers) based on aluminosilicate matrix are versatile candidates for bonding metals to metals or metals to ceramics. On curing, they result in an amorphous, crosslinked, impervious, acid resistant 3D-structures. Alkali activated aluminosilicate based ceramic adhesive was developed for bonding metals to ceramics and metal to metal, for high temperature applications. The bonding is achieved at 175℃ for 3 hrs, by solid state reaction of alkaline solution of allkalisilicate precursor with the refractory filler, contributing to the bulk aluminosilicate matrix. Lap shear strength of 2-4 MPa was obtained for bonding stainless steel. The XRD patterns show the amorphous nature of the aluminosilicate matrix, with mullite formation at higher temperatures. Thermogravimetric analysis shows that the weight loss is only due to the removal of water from the system by means of evaporation and polycondensation of Si-OH groups and Al-OH groups. This is followed by structural reorganisation in which aluminium ions are incorporated into the silicate chains forming the Si-O-Al network resulting in the bonding with the metallic surface. The system can withstand the maximum operational temperatures of the substrates and can be used for bonding different metallic or ceramic, joints/interfaces for RLV-TD/TSTO.