Abstract
For the purpose of developing a new breaking technology for brittle materials, measures for controlling the position and direction of the crack initiation as desired are discussed. By adopting a method of changing the indentation angle of a conventional pyramid type indenter for Vickers hardness tester, it has been found by experiments that, in case of the indentation angle of θi=3°, crack occurs straight only in the direction of inclination of the indenter on the line through the diagonal corners of the indent even when only one indent is made, and that the occurrence probability of the crack is rather high even in the range of low loading weight. In case of the indentation angle of θi=5, 7°, crack initiation is observed even from the corners in the direction different from the desired one, though the occurrence probability of the crack is high.
