Abstract: As the temperature resistance of fiber grating improving, the potential application of the fiber grating sensor in the high temperature thermal structure field is increasingly apparent. The high temperature bonding method is one of the most simple and effective methods to apply fiber grating sensors. However, the
high temperature environment may cause various high temperature adhesive failures. The bonding properties of fiber grating sensor and ultra high temperature ceramic are studied in high temperature tensile and shear experiments, and the high temperature bonding failure mechanisms are studied by macro and micro fracture morphology observations. The results show that the bonding failure is a mixed failure mode including interface damage and cohesive failure at two temperatures 500 and 650  ℃, and mainly adhesive cohesive failure, while at 650 and 800  ℃, bonding failure is mainly interface failure. Under a thermal and mechanical load, holes in the adhesive gradually develop to the crack weakening tensile strength, and simple high temperature heat treatment can improve the bonding performance.

Key words: failure mechanism, high temperature bonding, high temperature fiber grating sensor, ultra high temperature ceramic