Influence of the matrix composition, structure, and properties on the service life of a diamond drilling tool

Abstract

The microstructure and mechanical properties of four matrices of a complex chemical composition—VK15–Cu, VK15–Cu–Sn, VK20–Cu, and VK20–Cu–Sn—which are applied when fabricating diamond drilling tools, are investigated. The samples of matrices were formed by the infiltration of formations of the hard-alloy charge with copper at t = 1100°C and with bronze at t = 1000°C. The slices of diamond-free matrices were fabricated; their metallographic and electron probe microanalysis were performed; and their hardness, microhardness, density, and porosity were determined. Hardness of matrices was established by the HRC scale and microhardness was established using a PMT-3 device under a load of 2 N. It is revealed that (i) hard and strong diamond-tool matrices with open porosity no larger that 3% are formed by the infiltration of formations of the hard-alloy charge of VK15 and VK20 grades by the melts based on copper and bronze, and infiltration passes more completely when using bronze; (ii) matrices formed by the infiltration of formations of the hard-alloy charge of the VK15 grade with bronze are hardest. The application of matrices based on the hard-alloy charge of the VK20 grade when fabricating the drilling diamond tool is unreasonable because of an abrupt decrease in its abrasive ability when drilling hard materials.