A method of combined X-ray diffraction-X-ray fluorescence determination of Fe²⁺ in medium-basicity agglomerates of ferruginous quartzite ores is proposed. The method is based on measuring the integrated intensity of the magnetite reflex (111) with allowance for the characteristic x-ray lines of the elements that interfere with direct determination of Fe²⁺ by x-ray diffraction as a part of the additive intensity correction model. An integrated system ARL 9900 Workstation combines x-ray spectrometer and x-ray diffractometer in a common analytical space. Factors affecting the results of Fe²⁺ determination in iron ore agglomerates — change in the absorption coefficient of the sample, formation of magnetite solid solutions, presence of Fe²⁺ in the wuestite composition, the amorphous phase, and also in the phases of iron sulfides are considered. The ways of taking them into account which suggest the use of the intensities of characteristic emission x-ray lines of Ti, Mg, Ca, Si and S, as well as the integrated intensities of (200) wustite and (104) hematite reflexes as correction channels are considered. A calibration curve plotted within the concentration range 11.1 – 15.0% illustrates the dependence of the intensity of (111) magnetite reflex on the content of Fe²⁺ expressed as oxide. The accuracy and repeatability of the results obtained by combined XRD-XRF method match the requirements of GOST R 53657–2009 standard. The use of the combined x-ray diffraction – x-ray fluorescence method in industrial practice provides significant shortening of the time of determination of the chemical composition of the medium-basicity agglomerates of ferruginous quartzite ores (470 sec for determination of the elemental composition and Fe²⁺, which includes 360 sec for registration of the diffraction data).

 

We consider the features of sample preparation in determination of the microelement composition of algae using x-ray fluorescence analysis with total external reflection (TXRF). It is shown that complete acid decomposition in a microwave oven is the preferred method of sample preparation, which improves the intra-laboratory reproducibility of the results and reduces the detection limits for the majority of the detectable elements upon TXRF determination of the elemental composition of algae. The detection limit ranges within 0.3 – 0.6 mg/kg for most of the studied elements. Determination of the elements forming volatile compounds (Cl, Br, I, Hg) in algae samples using TXRF method appeared inexpedient.

A method for determination of diphenhydramine hydrochloride (DH) in pharmaceuticals using solid-phase spectrophotometry is presented. The method is based on DH extraction in the form of an ion associate with acidic dye (sulfonazo) from the solution on polyurethane foam.

A review of the features of test performances for the purpose of certification of difractometric measuring systems using short-wave radiation (x-ray and neutron radiation) which are intended for diagnostics of phase composition of substances and materials is presented. The main contribution to the uncertainty of the results of phase analyses is made by methodological errors, much more significant than instrumental characteristics of difractometers. The problems of conformity assessment to the claimed characteristics of the corresponding difractometric systems intended for various types of phase analysis are considered. For the identification (referenced as «qualitative» or «semi-qualitative») analysis, various structural databases and sometimes the values of the integral intensity ratios of Bragg reflections of certified standard reference materials (CSRMs) are used. To achieve high accuracy and reliability of quantitative phase analysis calculations of the angular positions of reflections should be performed on the basis on standardized (certified) reference (evaluated) data of crystallographic databases. To assess the reliability of the results, the equipment (difractometric measuring systems) should be tested together with the software and CSRMs sets should be also used. The sets of CSRMs include certified characteristics, i.e. the lattice constants (unit cell dimension), the intensity ratio of Bragg reflections, and/or the mass fraction of the composition of each phase, determined by Rietveld methods, which provide rapid achievement of higher accuracy and reliability. The sets of CSRMs used for testing and especially during operation of difractometers enable specialists and metrologists to ensure high quality and legitimacy of measurement results, which allows further refining of materials engineering technology and ensure the reliability and safety of products.

The equations of the elastic compliance matrix components are derived for arbitrary crystallographic directions determined by the Euler angles for cubic single crystals using the approach [4] developed by the authors which consists in transformation of the elastic compliance tensor in the principal axes into an arbitrary coordinate system with subsequent use of the Euler angles. Euler’s angles are applied in the following format: rotation around the hexagonal axis z (azimuth angle α), inclination of the hexagonal axis to an arbitrary position z’ (polar angle β), rotation around the new position of z’ axis (shear direction angle γ). Analysis of the equations derived for the components of elastic compliance matrix for cubic single crystals revealed invariant combinations of the components which, in turn, revealed relations between technical characteristics of the elastic properties of cubic single crystals: Young’s modulus along an arbitrary crystallographic direction, shear modulus and Poisson’s coefficients in a plane perpendicular to the selected crystallographic direction, shear modulus under torsion around this direction, and others. The validity of the obtained relations is verified in the calculations done for arbitrary crystallographic directions and various cubic single crystals. Calculations for single crystals of copper and nickel are presented.

The necessity of using theory of fractals — self-similar sets of fractional dimension — for analysis of the processes occurring in soft magnetic powder materials (SMPM) of the Fe-P alloying system which determine a body of their magnetic properties is shown. Flow diagrams for SMPM production, differing in the degree of deformation and thermal impact on the consolidating powder material of the Fe-P alloying system, methodology and results of magnetic measurements are considered. The technique of studying SMPM surface topography with a scanning probe microscope, providing a link between the length of the scan line L in a desired section, distance between the scanning point R in the same section, scaling parameters and fractal dimension Dare presented, as well as the results of three-dimensional surface reconstruction and scanning data processing. The revealed features of formation of the magnetic properties of SMPM attributed to the history of their production, the use of proven methods of measuring the magnetic properties of soft magnetic materials obtained by the proved technology used in powder metallurgy, demonstrated the possibility of using theory of fractals in production of the materials with desired properties to form a link between the technological features of the manufacture, fractal structure and magnetic properties of SMPM through determination of the topographic properties and geometric characteristics of the surface.

 

The size of the regions of coherent scattering and microstrain are determined using «double-Voigt» method and XRD data (integral breadth of 8 diffraction) for titanium carbide nanopowders obtained by plasmachemical synthesis. The results are compared with similar characteristics calculated by Williamson – Hall method. The coherently scattering domain size ranges within 12 – 180 nm. The size of coherent scattering domain determined by x-ray diffraction method for titanium carbide powder is close to the particle size calculated by the BET method. The Double Voigt method is advantageous for boundary (both for small and large) values of the size of titanium carbide particles. The broadening of x-ray diffraction peaks is attributed mainly to the small size of coherently scattering domains. The rms microstrain values are negligible (0.0001 – 0.0004).

 

The impact of thermal hardening and pulse laser treatment on the structure and operational characteristics two-carbide hard alloys is considered. The optimal regimes of laser pulse treatment which provided the lowest wear of the cutting edge of hardened tool are specified. Correlations between the duration of laser exposure and depth of structural changes in the hardened, wear and structural-phase changes attributed to laser treatment, fracture fractography and structural parameters of the hardened hard alloy are determined. An increase (on an average by 150 – 200 units) in the microhardness of the surface layer of T15K6 alloy is observed after pulsed laser treatment. The hardening trend is attributed to structural and phase transformations at the stage of pulse-laser exposure: formation of W2C carbide, saturation of the cobalt bond with tungsten and titanium carbides. A high rate of crystallization in the fused zone promotes formation of the structure with a high hardness. Laser heat treatment increases the performance of T15K6 hard alloy by 2 – 3 times

Conditions that cause violation of the integrity of the structure of polyamide materials in-service are analyzed. Methods proposed and developed by the authors with allowance for real meteorological conditions of the rolling stock operation in Russia are used to elucidate the causes of fatigue failure. Samples of glass-nylon composite (glass fiber reinforced nylon) are used to determine the necessary and sufficient indicators of strength characteristics of the material and derive experimental relationships to elucidate kinetics of the onset of fracture of polymer materials.

The butt welded joints of 30-mm plates made of titanium alloy VT6ch obtained by electron-beam welding are studied. The mechanical properties of the base metal and welded joints are determined. Plastic deformation in the broken welded samples is localized in the base metal at a distance from the weld which is characterized by a decrease in the value of the relative uniform elongation (stretch ratio) in the weld zone compared to the zone of base metal. Special specimens with a reduced working part have been developed to study the mechanical properties of the weld metal both along and perpendicular to the weld direction. The strength characteristics of the weld metal in both directions exceed the corresponding characteristics of the base metal while the plastic characteristics of the weld metal are lower than that of the base metal. The obtained results match the available literature data.

 

The standard methods of laboratory determination of the elasticity modulus of rocks under uniaxial compression are analyzed and their advantages and shortcomings are discussed. A test method and internal standard which enable physically correct determination of the static elastic properties of rocks upon change in their condition (temperature, moisture) are developed. Testing includes multiple loading of the specimen within the range of low reversible strains. The test is preceded by compulsory pre-compaction (2 loading cycles). Conditions of the reversibility and linearity of deformations are checked in subsequent cycles. The examples of determining the elasticity moduli of the siltstones of enclosing rocks from the «Botuobinskaya» diamond deposit as a function of their temperature and moisture are presented.

New data on the mechanical properties of Pt92.5Pd4Rh3.5 platinum alloy used in the catalytic systems in chemical industry are presented. The study was conducted in two stages: i) stretching of the wire samples and plotting of the loading diagrams ii) testing of the wire samples stretched on the wire drawing machines. Data on yield strength were plotted to the tensile stress-strain diagram. Combination of the two methods made it possible to obtain data on the strain resistance in the interval of relative reduction of 0 – 93%. The practical value of the obtained results consists in the possibility of using the dependencies in the form of graphs and approximated data to state and solve the specific boundary problems regarding of plastic metal working using, e.g., the finite element method.