Influence of disperse-hardening additive chrome diboride on the structure of carbide matrixes of PDC drill bits

Purpose. Development of highly effective composite diamond-containing materials based on WC‒Co matrices with CrB2 additives with improved mechanical and performance properties for creating matrices of rock-cutting tools for drilling oil and gas wells. Methodology. The assigned tasks were solved using a comprehensive research method, which includes a review and synthesis of literary sources; conducting analytical studies of existing composite diamond-containing materials; scanning electron microscopy (SEM) methods; X-ray phase analysis methods; calculation of experimental data by the Rietveld method, developed for the characterization of crystalline materials by powder X-ray diffraction; the Williamson-Hall technique. Findings. It has been established that the structure of the initial 94 %WC–6 %Co composite consists of WC phases with crystal lattice parameters a = 0.2906, c = 0.2837 nm and graphite with lattice parameters a = 0.2461, c = 0.6708 nm. The addition of chromium diboride to the composition of the 94 %WC–6 %Co sample leads to the decomposition of the CrB2 phase and the formation of the final phase composition: WC + B2CoW2 + Cgraphite + solid solution of tungsten and carbon in cobalt. Originality. It was shown for the first time that if the WC–6Co system is characterized by insignificant solubility of the components in each other, then in the WC–Co–CrB2 system there is a significant mutual dissolution of the components, which leads to a decrease in their sizes during the sintering process. When the threshold concentration (~4 %) of chromium diboride in the charge is reached, phases of the hexagonal WC group and new phases of the orthorhombic group B2CoW2 and amorphous carbon inclusions begin to form in the structure of the composite. Practical value. A highly effective composite diamond-containing material based on WC‒Co matrices with CrB2 additives with increased mechanical (hardness, crack resistance, compressive and bending strength) and operational (wear resistance, productivity) properties has been developed to create a highly effective rock-cutting tool for drilling oil and gas wells.