On crack-growth resistance curve fitting for ceramics

K-R-curves of crack growth resistance were studied for a particulate cerami c-metal composite in the system lanthanium chromite-chromium in the tempera ture range 20 to 1100 degrees C. It is shown that the K-R-curves can be des cribed satisfactory by an exponential function. With the use of this functi on, the similarity of the crack-growth resistance curves for the specimens tested at different temperatures can be demonstrated. The notch-size effect can also be minimized if the K-R-curves are normalized with respect to cra ck length, the normalizing factor being the parameter l of the exponential function. A possible background in the framework of the model of the crack- face bridging by frictional ligaments in a wake zone is proposed. (C) 2000 Elsevier Science Ltd. All rights reserved.