IMPURITIES AND INCLUSIONS IN DIAMOND GRAINS AS A FACTOR TO BE CONSIDERED WHEN USING DIAMOND GRINDING POWDERS IN DIAMOND TOOL

Abstract

The article presents the results of the influence of the content of impurities and inclusions in diamond grinding powders synthesized in the Ni-Mn-C and Fe-Si-C systems. As a result of their separation in a magnetic field, powders of magnetic and non-magnetic fractions are obtained, the magnetic susceptibility of which differs by an order of magnitude. It is shown that diamonds obtained in the Fe-Si-C system have well-defined magnetic properties; ferromagnetic elements of solvent alloys in inclusions (Ni+Mn for the Ni-Mn-C system and Fe for the Fe-Si-C system) predominate and make up 77.9–84.0% of the total number of inclusions present in diamond powders of the non-magnetic fraction, and in the magnetic fraction it is slightly higher and amounts to 94.5–93.1% for diamonds of both growth systems. The strength of diamonds of the magnetic fraction of both systems is higher in comparison with the strength of diamonds of the non-magnetic fraction, the heat resistance of diamonds of the non-magnetic fraction of both systems is higher in comparison with the heat resistance of diamonds of magnetic fractions. After the separation of diamond powders in a magnetic field into a number of fractions with different specific magnetic susceptibility, the homogeneity of the powders increases in strength compared to the homogeneity of the original powders before their separation. The performance of grinding wheels, with processing productivity (200 mm³/min), is more effective when using diamond powders of the magnetic fraction with a higher content of impurities and with greater strength. At a higher processing productivity (400 mm³/min), the wear resistance of wheels equipped with diamonds of the magnetic fraction decreases due to a decrease in their heat resistance. The wear resistance of diamonds of the magnetic fraction compared to the wear resistance of diamonds of the non-magnetic fraction for the Ni-Mn-C system will increase by a small amount, and for the Fe-Si-C system - by approximately 1.7 times.