FOREKNOWING METHOD FOR GENERATION OF CRACK OF PRODUCT MADE OF JOINTING CERAMICS AND METAL

• Main Authors: OKAMOTO AKIRA, ENOKIDO TSUNEO, HIRAI NAOKI
• Format: Patent
• Language: English
• Published: 24.07.1989
• Subjects: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIRCHEMICAL OR PHYSICAL PROPERTIES; MEASURING; PHYSICS; TESTING

PURPOSE:To foreknow the generation of a crack at the time of working by evaluating a residual stress state of the ceramics side from a variation of a length of a crack which is generated in a local area by a Vickers or Knoop indenter. CONSTITUTION:Plural test members 10 which have joined ceramics 2a of the same material as a product and various metals 3a are prepared, a Vickers or Knoop indenter is pushed into an influence part (x) and a non-influence part (y) of joint thermal stress at the side of the ceramics 2a, respectively and length C1, C2 of a generated crack is measured. From flexural strength sigma of the ceramics and fracture toughness values KC1, KC2 of the influence part (x) and the non-influence part (y) which are derived from C1 and C2, a thermal stress influence coefficient alpha=(KC2-KC1)/sigma.(C1/2)<1/2> is derived. On the other hand, surface grinding is executed to the test member 10. Based on the thermal stress influence coefficient of the test member in which a crack has been generated due to grinding and the test member in which the crack has not been generated, a crack generation threshold alpha0 is set. As a result, by comparing the thermal stress influence coefficient alpha of a product with the crack generation threshold alpha0, the generation of a crack can be foreknown prior to working.