GB600133A - Improvements in the abrasion testing of hard materials and particularly diamonds - Google Patents

Abstract

600,133. Testing physical qualities of materials. GRODZINSKI, P. Sept. 28, 1945, No. 25179. [Class 106 (ii)] A test-piece of diamond or other hard material, for carrying out wear resistance tests by an abrading process, consists of a right pyramid with a square base and four equilateral triangles as sides. The test-piece T, which may readily be obtained from crystals of the cubic system, is mounted in a holder H, Fig. 2, and abraded for a known time under a known pressure on a grinding wheel G operating at a known speed. The degree of abrasion, which is a measure of the hardness, may be determined by weighing, by means of a micrometer or microscope or by photographic means and, in the case of transparent materials, any internal defects may be studied with a microscope. In order to investigate the effect of the direction of abrasion, the test-piece may be orientated differently relative to the direction of rotation of the grinding wheel. Alternatively, directional differences may be compensated for by rotating the test-piece in addition to the grinding wheel. The testpiece T is held against a base-plate 9 of a holder, Fig. 3, by means of two plates 7, 8 having V-shaped recesses and carried by jaws 12, 13 which may be moved relatively by rotating a screw 10 having right- and left-handed threads. In a modified holder, Fig. 5, the test-piece T is clamped against a base-plate 17 by means of plates 18, 19 carried by spring-loaded stems 20, 21, engaged by a lever 24 which is raised or lowered by rotating a screw having a conical end 29.