Subcritical crack growth in Low Temperature Co-fired Ceramics under biaxial loading

The biaxial strength of Low Temperature Co-fired Ceramics was determined using the ball-on-three-balls test in several environments (dry oil, air and water). Subcritical crack growth phenomenon was observed, activated by the prolonged presence of humidity at the specimen surface. Whereas high strength values were reached during high-rate testing in dry oil, up to a 50% lower strength was measured on specimens immersed in water tested for longer periods. Experiments in a relative dry environment have shown for the first time evidence of two different crack growth mechanisms in this material. A model has been implemented to interpret the experimental results.