MODIFICATION OF HEAT-RESISTANT OXIDES AND CHLORIDES OF GRAIN SURFACES OF SYNTHETIC DIAMOND GRINDING POWDERS FOR APPLICATION IN GRINDING TOOLS

Further development of modern technologies of diamond processing is connected with application in the diamond tool of powders with new unique properties, special morphology of grains, with the increased chemical and thermal stability. To increase the heat resistance of diamonds, they are covered with a metal (metallization) or glass-ceramic layer, or introduced into the reaction mixture used in the synthesis of diamonds, alloying additives of certain elements. Recently, other methods of coating to increase the heat resistance of diamonds have been developed, such as: vacuum ion-plasma sputtering, epitaxial synthesis, magnetron sputtering, the method of liquid-phase deposition. The latter method is promising for modifying the grain surface of grinding powders of superhard materials by heat-resistant inorganic non-metallic coatings, as it is the most economically advantageous. Determining the features of the technology of modification by the method of liquid-phase application of heat-resistant inorganic coatings (oxides and chlorides of metals and nonmetals) on the surface of grains of grinding powders of synthetic diamond brand AC6, used for grinding tools in mechanical engineering. Modification was performed by the isothermal method of liquid-phase application of saturated solutions of both heat-resistant oxides (В2О3, Al2O3), chlorides (СаСl2, NaCl, MgCl2, FeCl3), and their mixtures (В2О3+СаСl2, В2О3+NaCl). Based on the analysis of the results of the research, it can be stated that the application of coatings of inorganic substances (some oxides and chlorides) increases the heat resistance of synthetic diamond grinding powders. Modification allows to reduce expenses of diamonds in wheels at grinding. Conditions for modification of heat-resistant oxides and chlorides, as well as their mixtures, grain surface of synthetic diamond grinding powders are determined. Modification of the surface of diamond grains with a combination of B2O3+Al2O3 is guaranteed to double the wear resistance of diamond wheels. It is established that in all cases of modification the roughness of the parameter Ra decreases. It is determined that by changing the surface modifier of diamond grains it is possible to affect the bearing capacity of the rough surface obtained by grinding. The development of effective ways to increase the heat resistance of grinding powders made of superhard materials, primarily abrasive grinding powders made of synthetic diamond powders, helps to improve the quality of the grinding tool.

Dependence of static strength of large single crystals of synthetic diamond type and Ib octahedral habit after heat treatment on their size

This article focuses on the problem of using large single crystals of type Ib synthetic diamond in single crystal and drilling tools. According to the literature review for the use of large diamonds in drilling equipment relevant conditions. The is shown possible negative effects of the temperature load on the diamond single crystal. The is presented developed technique for estimating the static strength of large diamond single crystals. It has been shown that microcrystals in the form of octahedra and cubes are formed as a result of heat treatment on the surface of synthetic diamond single crystals. The results of studies of the strength of large single crystals of synthetic diamonds of millimeter size are shown. In contrast to the classical approach, when IIb crystals are used for the production of drilling equipment, we present Ib crystals because they are closer to natural diamond in terms of physical and mechanical properties. The static strength criterion was used to assess the strength. It has been shown that crystals with a size of 1000 ... 1100 μm have a higher value of static strength than crystals with a size of 1200 μm and larger.

FINISH MACHINING OF THE CUTTING INSERTS FROM CUBIC BORINE NITRIDE BL GROUP COMPOSITE

Finishing methods of machining of superhard composite’s working elements based on cubic boron nitride BL group are considered. The results of the microgeometry formation research of the cutting inserts’ surfaces during machining by free powders of synthetic diamond, grinding wheels and a method of vibro-magnetic-abrasive machining (VMAM) are presented. It is shown that during VMAM the friction between the inserts’ surfaces and the abrasive particles result in microremoval of the material, which reduces the roughness of the cutting inserts’ surfaces. It is established that additional fine grinding with 14/10 mkm synthetic diamond powder provides the absence of microgeometry defects of the cutting inserts’ surfaces left by pre-machining. The result of high-quality rounding of cutting edges and the formation of surfaces of cutting inserts with less roughness is an increase in strength and wear resistance of metal-cutting tools in high-speed machining under conditions of significant loads.

EVALUATION OF THE MICROSTRUCTURE OF ZIRCONIUM DIOXIDE DURING ITS PROCESSING WITH VARIOUS TYPES OF DIAMOND TOOLS FOR FIXED PROSTHETICS IN DENTISTRY

Цель: определить характер механического воздействия на структуру образцов из керамики на основе диоксида циркония при её обработке различными алмазными инструментами, и оценка пригодности инструмента с различным способом фиксации абразива при многократном применении для дальнейшего использования. Материал и методы. Материал исследования - образцы на основе метастабильного тетрагонального диоксида циркония, изготовленные в зуботехнической лаборатории и стандартизированные по толщине (1 мм). Оценку влияния механических напряжений на структуру и свойства исходного материала проводили методом перфорации образца алмазными борами, содержащими специальный абразив для обработки циркония. Исследовались боры с различным типом фиксации абразива: № 1 - алмазный бор c синтетическим абразивом, закрепленным по типу ERA; №2 - алмазный бор с композитной фиксацией абразива импортного производства; №3 - отечественный алмазный бор с нанесением и фиксацией абразива методом гальванопластики. Методом сканирующей электронной микроскопии получали изображения результатов механического воздействия боров на образцы диоксида циркония при однократном и пятикратном использовании бора. Исследование структуру самого алмазного инструмента на предмет его пригодности для дальнейшего использования. Результаты. При однократном применении все представленные боры сохраняют микроструктуру диоксида циркония, что позволяет в дальнейшем работать с образцами с использованием адгезивной техники. При пятой обработке боры № 3 не пригодными для работы с керамическим образцом, боры № 2 остаются частично пригодными, боры №1 сохраняют свою пригодность для дальнейшего использования. Заключение. Керамические образцы на основе на основе диоксида циркония изменяются в процессе механического воздействия, что зависит от вида применяемого бора и кратности его применения. Боры с синтетическим алмазным абразивом на базе ERA остаются работоспособными даже после их пятикратного применения, боры с композитной фиксацией абразива к пятому применению остаются относительно работоспособными, а боры с гальванопластической фиксацией абразива к пятому применению приходят в полную негодность Purpose: to determine the nature of the mechanical impact on the structure of samples made of ceramides based on zirconium dioxide when it is processed with various diamond tools, and to assess the suitability of tools with different methods of fixing the abrasive with multiple applications for further use. Material and methods. The material of the study is samples based on metastable tetragonal zirconium dioxide manufactured in a dental laboratory and standardized in thickness (1 mm). The influence of mechanical stresses on the structure and properties of the source material was evaluated by perforating the sample with diamond bores containing a special abrasive for processing zirconium. Bores with different types of abrasive fixation were studied: № 1-diamond boron with synthetic abrasive fixed by ERA type; № 2-diamond boron with composite fixing of imported abrasive; № 3 - edematous diamond boron with applying and fixing the abrasive by electroplating. Scanning electron microscopy was used to obtain images of the results of mechanical action of boron on samples of zirconium dioxide with a single and five-fold use of boron. Investigation of the structure of the diamond tool itself for its suitability for further use. Results. With a single application, all the presented burs preserve the microstructure of the samples, which makes it possible to preserve the suitability of the sample for further work using adhesive technology. At the fifth processing, boron № 3 is not suitable for working with a ceramic sample, boron № 2 remains partially suitable, boron № 1 retains its suitability for further use. Conclusion. Ceramic samples based on zirconium dioxide change in the process of mechanical action, which depends on the type of boron used and the multiplicity of its application. Bores with synthetic diamond abrasives based on ERA remain workable even after their five-time application, bores with composite Abrasive fixation remain relatively workable by the fifth application, and bores with electro plastic fixation of the abrasive by the fifth application become completely unusable