Quality control of waste water requires development and improvement of the analytical instrumentation base and methods for determination of the contaminants, especially heavy metals. Here, we consider and characterize methods of greatest practical interest, i.e., elemental atomic absorption, atomic emission and mass spectral eco-analytical control of wastewater. Particular attention is paid to the methods dealing with separation and concentration of heavy metal impurities.

Results of a comparative study of several chemical methods of sample preparation used for cupriferous and polymetallic ores for further ICP-AES measurements of selenium are presented. Acid dissolution in a mixture of nitric and hydrochloric acid (3:1) as well as fusion with Eschka mixture are considered optimal methods providing complete decomposition of ore samples, shortening the duration of the sample preparation procedure, elimination of the selenium losses and decrease in blank correction. Multifactor experiment design is used to specify the ICP-AES parameters: the power of high frequency generator and speed of auxiliary and spray argon flows.

Analytical control of chemical composition of secondary lead-containing raw materials (battery scrap) is presented. Features of sample digestion are studied for active mass and metal fraction of the battery scrap with allowance for disolution of lead oxides, sulfates and sulfides, as well as antimony, copper, and iron impurities. Currently, there are no standard methods for determination of the content of lead, metal impurities and sulfur in the secondary lead-containing raw materials. To close the gap we have improved and refined standard gravimetric and titrimetric methods as applied to secondary lead-containing raw materials, metal impurities (Sb, Sn, Bi, Cu, Fe) and sulfur in the samples of metal fraction and active composition, obtained upon cutting and sorting of lead-containing batteries. Methods of mathematical statistics are used in data processing. Analitical expressions derived to calculate the content of lead, metal impurities and sulfur may be recommended for use in control of elemental composion in metallurgical processing of secondary lead raw materials, as well as in treatment of sewage and industrial wastewater.

The results of metallographic study (including optical and scanning electron microscopy, x-ray diffraction and chemical analyses) of defects on the outer surface of the large diameter pipes (LDP) are presented. There are two types of surface defects present in the problem-plagued zone: steel-making sliver and stress crack. Elucidation of the true cause of defect formation on the surface of metal products is rather difficult especially if the defects are unrelated in their features and do not have an explicit nature. Analysis of the phase and chemical composition of the flawed area provided determination of the true cause of their formation, i.e., local carburizing of the slab surface layers during production. Formation of the local areas of extra hardness on the metal surface results in appearance of slivers and stress cracks upon rolling. Hence, formation of defects is first attributed to violation of the steelmaking technology (carburization of the slab surface layers).

The results of studying the impact of plastic deformation on the magnetic and acoustic characteristics of the welded joint made of austenitic steel 12Kh18N10T are presented. The structural inhomogeneity in heat-affected zone is shown to result in an uneven distribution of the acoustic characteristics and magnetic properties of the material of welded joints. Martensite phase formed upon plastic deformation affects the properties of the entire material: the elasticity modulus of martensite differs from that of the initial phase, austenite. An increase in the volume fraction of martensite entails a decrease of the modulus of elasticity of the entire material and, hence, decreases the propagation rate of ultrasonic waves in the material. Change in the propagation rate of ultrasonic waves, leads to appreciable errors in measuring different characteristics of the material, e.g., in the thickness of the sheet in ultrasonic measurements of the thickness. Moreover, the release of martensite (ferromagnetic) changes the magnetic properties of the material. A dependence of the propagation rate of shear ultrasonic waves on the characteristics attributed to changes in the phase composition of austenitic steel upon plastic strain is observed at different strain rates. Proceeding from the aforementioned dependence, we developed an algorithm for determination of the thickness of metal of a welded joint from austenitic steel subjected to pressure treatment and plastic strain in service. It is shown that additional magnetic measurements of the characteristic attributed to a change in the phase composition of austenitic steel upon plastic strain provide a possibility of significant reduction of the errors of measuring thickness of the material of welded-joints.

The results of studying circumferential welds of small diameter present in various structural elements of aerospace engineering are presented. The method is based on the use of modern domestic x-ray tube with a massive target remote from the vacuum volume on a long anode tube. Design of the anode node provides panoramic radiation yield and getting x-ray image of the weld along the entire length in a single exposure. Special technical solutions in the design of the tube and generator of the x-ray device developed to adjust the dimensions of the focal spot provide attaining the required radiographic sensitivity and first and foremost sharpness of the resulting x-ray images. We consider the design and main technical characteristics of a specialized RAP-120PM x-ray unit. The results of using the device in real production conditions at one of the domestic engine-building enterprises of aerospace industry are presented.

Strain and energy fracture criteria under cyclic elastoplastic deformation are used to consider damage accumulation in conditions of single- and two-frequency loading modes. It is shown that change in the durability resulted from superposition of the high-frequency component of stresses (strains) on the basic process of low cycle loading can be determined by summation of fatigue damage components resulted from the basic and superimposed strains or by experimental determination of the coefficient reducing the destructive number of cycles which depends on the ratios of frequencies and amplitudes of interacting cyclic processes. With due regard for that, the components of damage from the impact of cyclic deformations correlate with the energy characteristics of the considered deformation processes, including the mechanical energy spent for deformation, thermal energy thus released and determined by recording changes in the temperature of self-heating of the material, and also the energy absorbed by the material prior to the fracture.

The contact strength, roughness and microstructure of the working surfaces of gear wheel teeth of a gas turbine engine manufactured using electric discharge machining (EDM)with subsequent thermochemical treatment are studied. Results of a comparative analysis of the materials of the parts processed according to the developed and serial manufacturing techniques are presented. The quality of the surface layer of the teeth working surfaces of gears operating in a gas turbine engine and manufactured by electric discharge machining are studied. The impact of different EDM modes on the quality of working surfaces and surface roughness is shown EDM increases the contact strength and reduces the roughness of the treated surface. Spectral analysis of surfaces manufactured according to the proposed technology revealed no changes in the surface chemical composition.

A new method of conventional yield stress determination from the kinetic diagram of indentation of a spherical indenter in the coordinates of the load - elastoplastic contingence is developed. The method is based on determination of the contact stress at the initial stage of indentation, at which the elastic and plastic components of the elastoplastic approach are equal.

A high-precision method for determination of nitrogen and basic substance in melamine using the Kjeldahl method and State secondary standard of the units of mass fraction and mass (molar) concentration of the components in solid and liquid substances and materials based on volumetric titration analysis of State Secondary Standard 176-1-2010 is developed. The technique has been used to determine metrological characteristics of the standard sample of composition of melamine State Standard Sample 10825-2016