Method for control of magnetic admixtures content in nanodiamonds of detonation synthesis
SUBSTANCE: nanodiamond is placed into installation for annealing, hydrogen is passed through and maintained at the temperature selected from the range of (900÷1100) °C, cooled down to room temperature. X-ray diffraction pattern is taken. Additionally spectrum of electronic paramagnetic resonance (EPR) is registered at room temperature. Availability of metal phases is identified.
EFFECT: invention makes it possible to increase sensitivity of magnetic admixtures content detection in nanodiamonds of detonation synthesis.
2 cl, 6 ex
The invention relates to nanotechnology materials, specifically to the processes of production of nanodiamonds by the method of detonation synthesis, and can be used to control the cleaning of magnetic impurities (specifically iron oxide) ultradispersed diamonds produced by the method of detonation synthesis of explosives, and output control (rejection) in their industrial production.
The known method of determination of mineral impurities in diamond /USSR GOST 9206-80. The diamond powders/, which is determined by the availability of inorganic, including magnetic impurities. In accordance with hanging diamond is burned in air atmosphere at 900°C for 6 hours. The result of a measurement is the ratio of the weights of the sample before and after burning.
The method allows to determine the presence and total number of non-combustible impurities in diamond, but does not allow them qualitatively to identify. The sensitivity of this method is about 1×10-4but it does not allow for qualitative identification of impurities.
There is a method of qualitative detection of the presence of iron compounds in carbon materials, in particular in nanodiamonds, by electron paramagnetic resonance (EPR) /Altshuler S.A., Kozyrev BM Electron paramagnetic resonance of compounds of elements of the intermediate groups. The 2nd edition is. M.: Nauka 1972 (672 pages)/. In accordance with register EPR spectrum of the sample material at room temperature, and the presence of a signal in the range of values of g-factor (4.1-4.3) shows the presence of iron compounds.
The sensitivity of the method is less than 1·10-6. The method also allows to determine the presence of Nickel compounds (g-factor 2.1-2.3) and cobalt (g-factor 6.32 or 3.12 depending on the connection type).
A known method of determining the content of relatively large amounts of impurities in the nanopowders is the registration of x-ray diffraction patterns with subsequent identification of the crystalline phases /Weinstein B.K. Modern crystallography (in 4 volumes), volume 1, the symmetry of the crystals. Methods of structural crystallography. M.: Nauka, 1979 (page 383)/.
However, the use of this method to the detonation synthesis nanodiamonds, which passed the standard procedure for chemical cleaning (processing in highly concentrated acids and oxidants /Dolmatov V.Y., Veretennikov M.V., Marchukov, VA, Sushchev V.G. Modern industrial possibilities of synthesis of nanodiamonds. FTT, 2004, volume 46, issue 4, str.596-600 (2004)/), as it was experimentally established, it is not possible to identify the impurity metal compounds. This is due to the lower sensitivity of the method of x-ray diffraction in comparison with the EPR method. B is further, metal compounds in samples of detonation synthesis nanodiamonds, specially alloyed with iron or other metals, also proved impossible to identify the known x-ray method.
The article selected by the prototype of the invention /Aeolianite, Magascene, Ajavon. The intercalation of ultradispersed diamond in aqueous suspensions. FTT, 2004, volume 46, issue 4, str-669 (2004)/, as a way of determining the presence of iron impurity in nanodiamond selected method of registration of x-ray diffraction with the subsequent identification of the crystalline phases formed by iron. It was found that for the detection of the formed crystalline phase of iron compounds in the samples of detonation nanodiamond synthesis of optionally entered by the admixture of iron, you need to register x-ray diffraction to expose the sample nanodiamond annealing (heat treatment in hydrogen at 500°C. However, the sensitivity of the method is insufficient for the detection of iron impurity at a concentration of less than 1%. For example, attempts to identify the impurity metal in the samples of detonation nanodiamond synthesis (without specially introduced impurities of iron) after annealing in hydrogen atmosphere at 500°C did not lead to success.
Thus, the disadvantage of the prototype is the low sensitivity of the op is adelene content of magnetic impurities in nanodiamonds of detonation synthesis, because magnetotactic materials, including the resulting developed by the authors method /Alexinsky AU, vul YA, jagovkina M.A. "Method of cleaning nanolab.", Russian Federation patent for the invention №2322389, priority from 13.10.2006/ for example the level of impurities is not more than 1·10-5.
The present invention solves the problem of increasing the sensitivity of the determination of the content of magnetic impurities in nanodiamonds of detonation synthesis.
The task is solved by a method of controlling the content of magnetic impurities in nanodiamonds detonatsionnogo synthesis, comprising annealing the sample detonation synthesis nanodiamonds in hydrogen atmosphere and then cooled to room temperature, the registration of x-ray diffraction and the identification of metallic phases in which the said annealing is carried out at a temperature selected from the interval (900÷1100)°C.
The authors experimentally found that the sensitivity of the determination of contents of metallic (magnetic) impurities can be greatly increased by changing the conditions of the annealing of the sample of nd, namely the increase of treatment temperature to a temperature in the interval (900÷1100)°C. Rise in temperature above 1100°C leads to a graphitization nd (irreversible changes in properties of the sample), when the annealing temperature less than 900°C, it was found that not p is oshodi significant aggregation of metallic impurities, leading to the formation of crystalline phases detected by x-ray diffraction.
Thus, by changing the conditions of annealing (heat treatment) it was possible to increase the sensitivity to a level that ensures the detection of the background (not made on purpose, and obtain in the process of detonation synthesis) of the impurity metal in nanodiamond.
To improve quality control, by increasing the reliability of determination of the content of magnetic impurities, after the identification of metallic phases additionally carry out the registration of the spectrum of electron paramagnetic resonance at room temperature with subsequent identification of the presence of metal impurities.
This effect is achieved due to the higher sensitivity of the EPR method compared with the method of x-ray diffraction, but manifests itself only after preliminary heat treatment of the sample nd when the annealing temperature corresponding to any value from the interval (900÷1100)°C.
Control of the concentration of magnetic impurities is produced as follows.
Sample nd placed in a special unit for annealing, pass a stream of hydrogen and the set temperature of the interval (900÷1100)°Spoke this temperature decrease to room, remove the sample from the unit for annealing and removing the Ute x-ray diffraction pattern, which is judged on the presence of magnetic impurities (metal phase).
In the absence of the diffraction pattern of trace metals advanced shooting range electron paramagnetic resonance (EPR) at room temperature. In case of absence in the spectrum of the EPR signals with values of g-factors of the corresponding magnetic impurities concludes the magnetic cleanliness of the investigated material.
As shown by the study authors, for process optimization - full aggregation of metal impurities at these temperatures is sufficient delivery time t annealing to the value determined from the relation t=t0-b ΔT, where
t0the time interval of 3 hours;
b - factor of 1.25·10-2h/°C;
ΔT is a value exceeding the minimum temperature of the temperature range of annealing (900°C), °C.
For the control experiments for the determination of magnetic impurities were prepared three test samples.
Sample 1 prepared from industrial nd (obtained by detonation synthesis in water, purified by the oxidation of non-diamond phase 50% nitric acid at 230°C) with ash 0.7%, during the registration of x-ray diffraction pattern showed the presence of impurities in titanium dioxide (non-magnetic impurity) and the absence of impurities of other crystalline phases.
Sample 2 prepared the C industrial nd (obtained by detonation synthesis in aqueous medium, purified by the oxidation of non-diamond phase 50% nitric acid at 230°C) with ash 0.7%, during the registration of x-ray diffraction pattern showed the presence of impurities in titanium dioxide (non-magnetic impurity) and the absence of impurities of other crystalline phases. The sample is optionally washed with 30% hydrochloric acid and distilled water. It can be expected that the number of magnetic impurities in the sample 2 is smaller than in sample 1.
Sample 3 prepared from industrial nd (obtained by detonation synthesis in water, purified by the oxidation of non-diamond phase 50% nitric acid at 230°C) with ash 0.7%, during the registration of x-ray diffraction pattern showed the presence of impurities in titanium dioxide and the absence of impurities of other crystalline phases. The product of this party washed with 30% hydrochloric acid under ultrasonic irradiation and distilled water in accordance with the patent of the Russian Federation No. 2322389, according to which the resulting nanodiamond should not contain magnetic impurities.
Studies of x-ray diffraction was performed on the diffractometer "Geigrflex D/max-RC, firms Rigaku (Japan), with the following instrument settings: radiation α With (λ-1,A) monochromatization; step scan; accumulation time of the signal at one point 2 seconds; a registration step of 0.02°; current and accelerating voltage x-ray tube 70 mA, 40kV; scan interval - (3÷10) degrees 2θ; divergentional slit (DS)=1°; Salerosa slit (SS)=0,15°; receiving slit (RS)=1°.
EPR spectra were obtained on a device company Varian model R160. The generator frequency was 9.45 GHz, in the range of magnetic fields (0÷500) MT, the additional frequency modulation 100 kHz, the experiment was conducted at room temperature. The signal with the specified g-factor was observed when the magnetic field strength in the range (136÷150) MT.
Sample 1 was annealed in order in hydrogen at a temperature of 1000°C, which meets specified in the claims of the temperature interval, for 1.75 hours. X-ray diffraction pattern of a sample of registered diffraction peaks identified as the crystalline phase of iron.
Same as in example 1, but the temperature of 900°C, which corresponds to that specified in the claims of the temperature interval, the duration of annealing was 3 hours. X-ray diffraction pattern of a sample of registered diffraction peaks identified as the crystalline phase of iron.
Same as in example 1, but the temperature was 1100°C, which corresponds to that specified in the claims of the temperature interval, the duration of annealing was 30 minutes On the x-ray diffraction pattern of a sample of registered diffraction peaks, identified as phase Cree is metallic iron.
Same as in example 1, but the temperature was 1200°C, while the temperature is beyond the scope specified in the claims of the interval, the duration of annealing was 20 minutes X-ray diffraction pattern of the sample has a complex and uninterpreted character due to graphitization nd. The sample lost consumer properties.
Sample 2 was annealed in order in hydrogen at a temperature of 1000°C, which corresponds to that specified in the formula of the invention according to claim 1 temperature interval within 1.75 hours. But x-ray diffraction pattern of the sample was not registered diffraction peaks corresponding to crystalline iron. However, the EPR spectrum showed the presence of a signal in the range of field values (136÷142) MT, the corresponding g-factor of 4.3 characteristic of the iron valence state of Fe+3. Thus, the application of the method according to claim 2 allowed to register the presence of traces of iron, which shows the increase in the reliability of the method.
Sample 3 was annealed in order in hydrogen at a temperature of 1000°C for 1.75 hours, which corresponds to that specified in the claims of the temperature interval. X-ray diffraction pattern of the sample the presence of crystalline iron is not detected. Range of EPR shows no signals in the range of field values (136÷142) MT that meet the observed g-factor 4.3, characteristic of the iron valence state of Fe+3. Thus, the control method confirmed the absence in the sample of detonation nanodiamond synthesis of iron impurity, when the cleaning method according to the invention by the patent RF №2322389.
1. The method of controlling the content of magnetic impurities in nanodiamonds detonatsionnogo synthesis, comprising annealing the sample detonation synthesis nanodiamonds in hydrogen atmosphere and then cooled to room temperature, the registration of x-ray diffraction and the identification of metallic phases, characterized in that the annealing is carried out at a temperature selected from the interval (900÷1100)°C.
2. The method according to claim 1, characterized in that after the identification of metallic phases additionally carry out the registration of the spectrum of electron paramagnetic resonance at room temperature with subsequent identification of the presence of metal impurities.
FIELD: physics, optics.
SUBSTANCE: invention relates to methods of determining physical conditions at which phase transitions in metals and alloys take place. The method is based on joint analysis of the image of fragments of the surface of analysed material and luminance spectra of visible light reflected from the said surface, taken before and after the external physical action causing the phase transition. The analysis results are processed using special computer software.
EFFECT: invention simplifies diagnosis of phase transitions, increases accuracy and degree of automation of processing experimental results.
FIELD: physics, measurement.
SUBSTANCE: method involves experimental research of substance within temperature range beginning from T=0 K, measurement of heat capacity of substance within this range, and make conclusion on a zone of metastable substance state change by abrupt jump.
EFFECT: possibility to define zone of metastable state in substance.
4 cl, 11 dwg
FIELD: measuring technique.
SUBSTANCE: method can be used for measuring speed of phase transitions in movable structures provided with balance rings of domestic washers provided with dismounted top desk. Weight with mass of 0,5 kg is suspended inside drum of washer at height corresponding to center of gravity of internal movable part. Auto-balancing device is subject to cooling to temperature below 0°C to let solution inside hollow soldered metal balls freeze. Drum during process of cold air to come, inside for making solution freeze, is periodically driven into rotation and then it is stopped. Critical non-balanced mass of mechanical system is measured any time due to suspending additional weights and determining that masses of them, with which the drum touches wall of case. Speed of phase transitions is measured when solution gets frozen inside balls. Then test are conducted to study process of solution melting by using more perforated metal balls, for which purpose the balls are preliminary filled with ice or snow on base on high density solutions. To defrost solution, air compressor is turned on to pump warm air up inside cavity under drum. Drum is periodically driven into rotation and stopped during process of warm air intake. Critical un-balanced mass of mechanical system is measured any time by suspending additional weights to determine that mass of weights, at which mass the drum touches wall of case at rotation. Speed of phase transition in "solid body-liquid" system is measured during defrosting of solution.
EFFECT: improved precision of measurement.
8 dwg, 1 tbl
FIELD: heat-and-power engineering; other industries; installations for the scale formation analysis.
SUBSTANCE: the invention is pertaining to the scale formation analysis in the close to the industrial conditions at the controlled values of such parameters as the pressure and concentration of the salts in the working liquid. The installation for the scale formation analysis made in the form of the evaporation chamber includes: the installed with possibility of replacement heat-exchange system made in the form of the horizontal pipes with the electric heating elements located inside them, on which surfaces formation of the scale silt takes place; the system of feeding of the working liquid into the evaporation chamber and the mean for the steam condensation linked with the evaporation chamber by the steam withdrawal trunk. The installation is additionally supplied with the mean of the pressure control in the evaporation chamber, including the needle-type valve arranged in the steam withdrawal trunk and the system of withdrawal of the working liquid from the evaporation chamber including the needle valve mounted in the working liquid withdrawal trunk. The invention allows to expand the range of the conditions for analysis of the scale formation and to increase reliability of the analysis results.
EFFECT: the invention ensures expansion of the range of the conditions used for analysis of the scale formation and the increased reliability of the analysis results.
SUBSTANCE: method provides usage of temperature detectors to transform electric signal, and identification of type of phase transition. Electric Signal from temperature detector is corrected for value of electric signal which is generated by phase transition of material. Correcting electric signal is achieved by means of additional probe.
EFFECT: improved precision of measurement.
4 cl, 9 dwg
FIELD: measuring technique.
SUBSTANCE: while warming sample up, average value of square of voltage of thermal electrical; fluctuations is measured at terminals of measuring converter. Maximal value, which corresponds to glass transition temperature, is measured, at which temperature the value of dielectric permeability is found and value of hardness coefficient is calculated. Method can be used for measurement of equilibrium hardness coefficient of polymer chains for polymers in unit.
EFFECT: improved precision of measurement.
1 dwg, 6 tbl
FIELD: measuring technique.
SUBSTANCE: method comprises testing two samples of the lubricant of the same mass, the first sample being tested without catalyzer and the second sample being tested in the presence of catalyzer, determining transparency coefficient by means of photometric measurements, plotting time dependences of the transparency coefficient, and determining oxidation stability of the lubricant from the equation presented.
EFFECT: enhanced precision.
3 dwg, 1 tbl
FIELD: measurement technology.
SUBSTANCE: method involves carrying out experimental temperature measurements of cooling liquid avalanche dissociation on hot surface under static conditions, without liquid flow being arisen.
EFFECT: simplified cooling liquid quality control process; reduced tested substance quantity in samples under test; personnel safety in carrying out tests.
FIELD: investigating or analyzing materials.
SUBSTANCE: method comprises heating specimens to be analyzed with a rate of 10 deg/min, using standard initial polymineral clays, selecting temperature intervals 20-200°C, 600-800°C, and 20-100° C from the thermo-analytic curves of the standards, determining the reference values in the intervals, determining mass losses, and choosing maximum values of the mass losses in the intervals for the calculation of the fraction ration of clays.
EFFECT: enhanced accuracy of measurements.
6 dwg, 1 tbl, 6 ex
FIELD: inspection of quality of oil products.
SUBSTANCE: permanent-weight lubricant is subject to heating in thermo-stable glass cup at three temperatures at least, which temperatures exceed that one of beginning of oxidation and then it is subject to mixing by glass mixer at constant speed during 12 hours or less. Samples for photometry are selected in equal time intervals. Factor of absorption of light flux by oxidized oil Ability to evaporation is measured by weighing sample before and after test. Graphical dependences of theses parameters are built relatively temperature of testing. Thermal-oxidative stability of lubricant is determined by critical temperature of service ability, by temperature of beginning of oxidation and by temperature of beginning of oxidation.
EFFECT: improved efficiency of measurement.
SUBSTANCE: invention refers to pharmacy, namely identification, estimation of quality and safety of original and reproduced medical products. Described comparative estimation of physiological activity of original medical products and reproduced medical products or related preparations implies that by means of EPR spectroscopy and spin probes influence of these products on erythrocyte, lymphocyte and thrombocyte membrane structures released of the same blood sample depending on active component concentration in solution and contact time are examined by comparison of corresponding data obtained within concentration corresponding to maximum therapeutic dose.
EFFECT: method enables comparing of pharmaceutical preparations - originals and generics, or pharmaceutical substances, with various impurity compounds, both within quality assessment and from the point of safety for patients.
3 ex, 3 tbl
FIELD: inspection of degree of lacing of polyethylene.
SUBSTANCE: tested and reference samples are placed into resonator of electron paramagnetic resonance spectrometer, spectrum of absorption of electron paramagnetic resonance is recorded. Amplitude of derivative and width of absorption line of tested and standard samples is found from spectrum recorded correspondingly to subsequent determination of degree of lacing from formula K=I'ΔH2mref/I'refΔH2 refm, where I' and I'ref are amplitudes of derivative of absorption line of tested and reference sample, ΔH and ΔHref is width of absorption lines of tested and reference samples, m and mref are masses of tested and reference samples.
EFFECT: improved precision of inspection; simplified method of inspection; improved efficiency of operation.
SUBSTANCE: invention relates to chemical methods of purifying natural diamonds, where contaminants are in form of organic and mineral deposits and metallic impurities formed through enrichment of diamond-bearing rocks, as well as synthetic diamonds in which metallic impurities accompany synthesis, with the aim of using the said diamonds as grinding powder in electroplating when making a precision diamond tool. The method involves treatment of diamond at normal atmospheric conditions in a solution with the following composition: water, hydrofluoric acid, nitric acid, sulphuric acid and hydrogen peroxide in volume ratio of 5:1:1:2:(1-10) respectively, with periodic addition of hydrogen peroxide in proportion to its consumption. Nickel metal is added to the solution before treatment of the diamond.
EFFECT: invention provides comprehensive purification of fine diamond (4-160 micrometres) from organic contaminants and metal microinclusions.