Accurate measurement of strength and fracture toughness for miniature-size thick diamond-film samples by three-point bending at constant loading rate

摘要: Abstract Fracture strength and fracture toughness (K IC ) of miniature-size thick freestanding diamond film samples were accurately measured by three-point bending at a constant loading rate. A specially designed testing rig, capable achieving rate as small −1 was used, which is beneficial for accurate measurement the brittle materials like films. novel method employed to nucleate control length pre-crack. fixture used ensure that sample tested in near-perfect vertical position, required ASTM E399 standards. Effects dimensions on are discussed; it shown can be determination toughness. However, toughness, use pre-cracked absolutely necessary. The effect configuration discussed detail. In addition frequently reported two configurations (with nucleation growth surface tension, respectively), third with edge tension also discussed. Weibel modulus found strongly dependent configuration. significance these findings