Estimation of the efficiency of destroying hard rocks by composites sintered in the diamond-carbonate system

The purpose of this work is to substantiate the possibility of using a new composite sintered in the "diamond-carbonate" system for equippingdiamond drilling tools with high wear resistance and efficiency of rock destruction. The research technique consisted in establishing the influence of the wear resistance of the cutting edge of the samplesof a superhard composite diamond-containing material on the efficiency of rock destruction, assessed by the granulometric composition of its sludge. Research results. The two-phase superhard composite materials diamond – CaMg(CO3)2 and diamond – SrCO3 were obtained as a result of sintering by the method of impregnation of diamond micropowder with carbonate melts under conditions of a high pressure of 8.0 GPa and a temperature of 2100 °C. Wear resistance of the investigated composite sampleswas determined by based on the results of turning the core of granite from the Korostyshevskoye deposit of the X category of drilling. Determination of the size and shape of particles of granite fragments of the Korostyshevskoye deposit, taken during its destruction was carried out by laser diffraction and digital image analysis using a Microtrac Sync analyzer.The relationship between the degree of its wear of the cutting edge of composite samplesand the energy consumption of rock destruction, the size distribution of particles in the cuttings sample and their specific surface was established after analyzing the results of the study of wear resistance and the nature of their wear. Plates of the diamond–CaMg(CO3)2 composite, which have a higher wear resistance compared to other composites, are characterized by an increase in the proportion of large particles in the cuttings sample and a decrease in the value of their specific surface, which indicates a more rational use of energy, which goes to a greater extent for destruction rock and to a lesser extent for friction and wear. Practical value. The research results allow us to make a conclusion about the advisability of equipping a drilling rock cutting tool with samplesof a diamond–CaMg(CO3)2 composite in order to increase its wear resistance and the efficiency of rock destruction.

Experimental Study of Surface Etching in Synthetic Diamond Microcrystals due to Presence of Cu and Fe at High Pressure

In the present work, microcrystals of synthetic diamond extracted from a metal-diamond composite were investigated. A composite based on Cu and Fe was obtained by sintering at a pressure of 4 GPa and a temperature of1300 °C. The experiments were carried out using a split-sphere high-pressure apparatus BARS. The high-pressure cell was made of refractory oxides ZrO2, CaO, and MgO using a tubular graphite heater. In the composite, diamond grains were in close contact with neighboring diamonds, and the metal phase filled the interstices. The study of the diamond crystals demonstrated the appearance of newly formed micromorphological structures on the surfaces in the form of numerous cavities of irregular shape on the faces of octahedron, as well as pyramids on the faces of cube, the morphological elements of which follow the contours of the cube face of the diamond. Thus, the results of the work evidence for the processes of etching of the diamond crystals during the experiments, which is associated with the presence of metallic iron in the composite. This type of etching forms a roughly cavernous surface on the diamond crystals, which can be considered as an additional factor for improving the metal-diamond bond in copper-based composites.

Процессы самоорганизации частиц детонационного алмаза на подложке в ходе конденсации углерода из парогазовой фазы

Processes in which the island structure is ordered occur in composite carbon films produced by preliminary population of an amorphous substrate with a detonation-diamond system and subsequent condensation of carbon from the vapor–gas phase. These processes, observed already upon filling of the substrate with diamond-growth centers, are manifested in that there appears a structural periodicity of the islands. It was found that the condensation of carbon on the populated substrate is accompanied by the evolution of the island structure of primary growth centers. This consists in that a hexagonal packing of the islands is formed, with the size of these islands increasing by two orders of magnitude. All these structural features of how a composite diamond-carbon film is formed indicate that self-organization processes occur in the system of diamond islands when carbon atoms are condensed and interact with primary diamond crystals.

STUDYING OF POLYCRYSTALS STRUCTURE BASED ON DIAMOND MICROPOWDERS AFTER MODIFYING BY CARBIDE-FORMING ELEMENTS

Results of thermobaric processing of diamond micropowders after their modifying by silicon, titan and tungsten are presented. The composite diamond micropowders such as diamond – silicon, diamond – titan and diamond – tungsten are received after the preliminary annealing in the protective atmosphere. As a result of agglomeration of the modified diamond micropowders under the conditions of high pressures and temperatures the carbides formation of the refractory compounds promoting sintering of diamond grains takes place.