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The effect of the addition of ZrO
2
micropowder (in the range from 0 to 10%) on the structural changes of the hard alloy matrix in the area of fracture as a result of impact loading of a sample of ...composite diamond-containing material (DCM) 25С
diamond
–70.5WC‒4.5Co wt % was studied, formed by the method of spark plasma sintering in the temperature range from 20 to 1350°С at a pressure of 30 MPa for 3 min. It was found that in the DCM sample without ZrO
2
additive, the structure of the hard alloy matrix has the appearance characteristic of brittle fracture, which is evidenced by the smooth relief of the fracture surface. In this case, the destruction of the DCM sample occurs by chipping of the components of the hard alloy matrix, which leads to a decrease in its wear resistance. The introduction of the ZrO
2
additive in the amount of 4% into the composition of DCM causes a change in the structure of the fracture surface. On the fracture surface of the carbide matrix of the DCM sample, nanopores with a structural size of ~100–500 nm are formed as a result of viscous (pitting) fracture. At the same time, in addition to the formation of dimples on the fracture surface of the hard alloy matrix, a highly developed relief is simultaneously formed on the surface of the diamond grain, which is evidence of improved diamond retention and increased wear resistance of the composite. With a further increase to 10% of the ZrO
2
additive in the DCM composition, a more pronounced microrelief with the presence of deep dimples and microcracks is formed on the fracture surfaces of the hard alloy matrix and diamond grain. It is proposed to use the type of relief of the fracture surface of sintered DCM samples during impact fracture at room temperature as an assessment of the characteristics of the strength of diamond retention.
The work is devoted to increasing the service life of PDC bits when drilling rocks alternating in hardness by equipping tools with additional superhard elements. Experimental data have shown (ISM NAS ...(Ukraine)) that superhard elements have the following composition: diamond, tungsten carbide, cobalt, chromium diboride and zirconium dioxide, and the latter two components are included in the composite in a ratio of 2:4. Inserts made of a new composite have minimal cracking, increased wear resistance and cutting ability. In the manufacture of new PDC bits, the bottom-hole part of the blades should be equipped with working elements consisting of a PDC cutter and an insert made of superhard composite. It is shown that when the working edges of the PDC cutter and the end of the undercut insert are placed in the same plane, the efficiency of downhole deepening is ensured. To preserve the diameter of the well, the side surface of the blades is also equipped with calibration inserts made of a new composite. The theoretical dependence of the tool feed rate is obtained depending on the number of calibration inserts in the tier, the rotation frequency of the column and the diameter of the inserts.
The most important scientific and technical problem in the field of field development is the most complete extraction of oil from the subsurface while ensuring high rates of development. The solution ...of this problem is complicated by the fact that most of the oil fields in the Western region of the Republic of Kazakhstan have moved to a late stage of development. At the deposits of the Mangystau region, the composition of borehole products includes resins, asphaltenes, paraffins, salts. All this leads to colmatation of bottom-hole zones of wells (CCD), a decrease in the pick-up rate of injection wells, a decrease in the flow rates of producing wells. New progressive methods of processing the bottomhole zone include methods of shock-wave action on productive rock strata. The purpose of the PFT shock wave processing (SWP) of wells is to restore and increase the pick-up of injection wells in combination with the use of chemical compositions, as well as to intensify oil production at surrounding producing wells. The SWR was carried out at 10 injection wells of the fields of JSC "Ozenmunaigas". For each injection well, groups of producing reacting wells (cells) were identified, for which the effect was calculated according to the methods. According to the results of the PFT (pilot field tests), the technological effect (increase in pick-up) was obtained at 6 injection wells and the effect of additional production was achieved at 5 cells of reacting producing wells. The success rate of the technology was 50%.
We examined 663 patients who were admitted to the clinic by ambulance, for determine the factors of clinical deterioration and progression of ischemic stroke in the acute period of the first 24-72 ...hours. Among the patients received in the acute period, a fatal out come occurred in 7.23% (48) patients, men- 45.8% and women - 54.2%.At the time of admission to the hospital, almost 96.7% of patients with acute ischemic stroke had a disorder of consciousness from stunning to coma. The most significant risk factors for the development of ischemic stroke among 663 patients were arterial hypertension - 80.1%, chronic heartfailure - 57.9%, coronary heart disease - 25.5%, atrial fibrillation - 19.5%, type 2 diabetesmellitus 12.5%. In accordance with the international criteria of TOAST (1993), pathogenetic mechanisms of the development of isch- emic stroke have been determined in patients. Atherothrombotic stroke developed in 303 (45.7%), cardioembolic stroke in 185 (27.9%) patients, lacunar stroke in 167 (25.2%) patients, undefined genesis stroke in 8 (1.2%) patients.The progression of neurological deficiency in ischemic stroke is a bad prognostic factor.
A horizontal rod of limited length is considered. Radius of the rod varies linearly along its length. The cross-sectional area of the left end is greater than the right one. The lateral surface of ...the test rod is completely insulated. The heat flow is fed to the cross-sectional area of the left end. Through the cross-sectional area of the right end of the rod, heat exchange takes place with the surrounding medium. The field of distribution of temperature, displacement, three components of deformation and stresses are determined in the work, provided that both ends of the rod are rigidly fixed. And also, the magnitude of the elongation of the rod is determined when one end of the rod is fixed and when the other is free. In the case of fixing the two ends of the rod, the magnitude of the resulting axial compressive force is also calculated. When studying the rod, the fundamental laws of conservation of energy were used.
We examined 663 patients who were admitted to the clinic by ambulance, for determine the factors of clinical deterioration and progression of ischemic stroke in the acute period of the first 24-72 ...hours. Among the patients received in the acute period, a fatal out come occurred in 7.23% (48) patients, men- 45.8% and women - 54.2%.At the time of admission to the hospital, almost 96.7% of patients with acute ischemic stroke had a disorder of consciousness from stunning to coma. The most significant risk factors for the development of ischemic stroke among 663 patients were arterial hypertension - 80.1%, chronic heartfailure - 57.9%, coronary heart disease - 25.5%, atrial fibrillation - 19.5%, type 2 diabetesmellitus 12.5%. In accordance with the international criteria of TOAST (1993), pathogenetic mechanisms of the development of isch- emic stroke have been determined in patients. Atherothrombotic stroke developed in 303 (45.7%), cardioembolic stroke in 185 (27.9%) patients, lacunar stroke in 167 (25.2%) patients, undefined genesis stroke in 8 (1.2%) patients.The progression of neurological deficiency in ischemic stroke is a bad prognostic factor.
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