Round-robin test on the fracture toughness of ceramic thin plates through modified single edge-precracked plate method

Round-robin tests on the modified single edge-precracked plate method were conducted successfully to determine the fracture toughness of Si3N4, AlN and Al2O3 thin plates. A small, thin single edge notched plate with the thickness of 0.32 or 0.64 mm was bonded on one side of a brass beam and the assembly was loaded in a three-point fixture to introduce the precrack. A special 3pt-bending fixture with a vertical slit was employed for the strength test. Good matches in the resultant fracture toughness were obtained between laboratories regardless of the thickness of ceramic plate, confirming the reliability of the new method.