The Preparation And Properties Discussion Of The Phosphate Adhesives

The adhesives was prepared by phosphoric acid, aluminum dihydrogenphosphate, aluminum hydroxide and fillers. The adhesives were used to join mulliteceramic/ceramic system. The weightloss rate and tensile strength were discussed, andthe effect of the fillers ratio on tensile strength was discussed. The bonding effect andmorphology of adhesives were discussed by SEM analysis. The chemical compositeand the chemical bonds were analyzed through TG-DSC, XRD and IR tests.It can be concluded from the tensile strengths analysis that the strengths of thejoined system was affected by the ratio of the mullite and silica powders. The bondingstrength was higher when the ratio was large. Through comparison, the bondingstrength of the aluminum phosphates was the highest among the adhesives, thestrength of which can reach9.25MPa and the heat treatment of it temperature was800℃. The highest strengths of the aluminum dihydrogen phosphate andaluminum-magnesium were5.06MPa and7.46MPa, respectively.It can be inferred from the SEM analysis that the bonding effect was excellentduring the heat treatment process and there was no apparent bonding interfacebetween the adhesive and the matrix. The internal morphology became denser withthe treated temperature increasing. Many large cracks emerged when the temperaturewas over1000℃. The cracks may reduce the bonding strength of the whole system.From the TG-DSC, XRD and IR analysis, it can be known that there were threestages during the heat treatment process. The free water and bound water would losebetween the room temperature and200℃. When the temperature reached200℃to600℃, shrink polymerization reaction happened and the polymerization degreereached the quite high when treated temperature was higher than800℃.From analyzing the properties of the joined mullite ceramic/fiber brick system byaluminum phosphate adhesive, it can be known that the highest strength which wastreated at high temperature was6.58MPa, and the highest high-temperature strengthwas1.23MPa, with the tested temperature of200℃.