Materials Science Forum Vol. 1037

Abstract: Development and implementation of new methods of high-energy surface treatment of structural steels is one of the priorities of modern materials science One of the urgent problems of power engineering is the development of effective processing technologies that allow parts to provide the required properties of working surfaces. The use of laser technologies helps to increase wear resistance, corrosion resistance, reduce the duration of chemical and thermal treatment time and other technological characteristics that can improve the quality, durability and efficiency of parts, increase economic and environmental effects.

Abstract: Possible causes of mass transfer acceleration of carbon atoms and alloying elements in the surface layers of steels and alloys under extreme heating, under pulsing laser irradiation in particular, are considered. The research shows that the anomaly accelerated mass transfer, including diffusion in particular, in steels and alloys under fast laser heating has a cooperative character and is a result of a simultaneous action of several processes of different physics. It is proved that the carbon atoms mass transfer parameters and alloying elements depend on the scale and the level of emerging tension, relaxation of which goes along with a local plastic deformation, and occurrence of increased number of linear defects in crystal structure.

Abstract: Phosphating has long been successfully used as a method of protecting metal products and structures from corrosion. The possibility of obtaining non-ferrous phosphate coatings on steel by cold method was investigated. Compositions of cold phosphating solutions for the deposition of colored phosphate coatings of green and blue colors are proposed. To obtain green phosphate films, chromium salts and procyon olive green dye were introduced into the compositions of cold phosphating solutions. To obtain phosphate films of orange color, cobalt salts were introduced into the compositions of cold phosphating solutions. To obtain blue phosphate films, methylene blue and Prussian blue were introduced into the compositions of cold phosphating solutions. It was found that colored phosphate films are worse at preventing metal corrosion. Colored phosphate coatings have a higher porosity and are less uniform compared to modified phosphate films.

Abstract: The objects of the study were powder samples PV-NiCr16Al6Y and PV-Ni75Al23W, intended for the formation of a sublayer in heat-shielding coatings. The aim of this work is to develop and study a sublayer with a complexly organized structure of a functionally graded material of the superalloy-sublayer-ceramic system for operation under thermal cyclic loads and high-temperature gas corrosion. Experimental samples of binding materials for heat-protective coatings (HPC) were obtained by the method of spark plasma sintering (SPS) at T = 1050 °C / 15-30 MPa / 5 min. Methods of laser diffraction, X-ray structural analysis, optical and scanning electron microscopy, X-ray fluorescence spectroscopy, microdurometry were used to study powders and consolidated materials. It is shown that irregular powders contain individual particles of some components - in PV-NiCr16Al6Y powder these are particles of chromium and yttrium, in PV-Ni75Al23W - tungsten and chromium. Consolidated sublayers of such powders exhibit inhomogeneity and irregular porosity. To solve the problem of forming a homogeneous binder sublayer, mechanical alloying of the powders before sintering is proposed. It was found that MA increases the homogeneity of the structure, excludes local inclusions of unreacted particles, and increases the activation of consolidation. MA and subsequent sintering opens up wide possibilities for controlling the structure, including the porosity of the sublayers, and specifying various options for the HPC architecture. Experimental samples of HPC on an Inconel 625 substrate with a mechanically activated PV-Ni75Al23W sublayer and dioxides Zr/Y (YSZ) outer ceramics were obtained by the SPS method. A model of the architecture of a HPC made of a layered binder with different porosities is proposed.

Abstract: The article presents the research results on obtaining coatings on steels 1030 and AISI 420 by the method of electrospark deposition and subsequent smoothing by means of ultrasonic surface plastic deformation (USPD). Intermetallic alloys consisting mainly of NiAl and Ni₃Al phases were used as materials for obtaining coatings. It was found that the coatings consist of columnar crystallites of complex composition and have high plastic properties. To ensure the minimum parameters of the surface roughness of the obtained coatings, it is necessary to carry out 3-6 times of ultrasonic surface treatment.

Abstract: In this work, a high-entropy alloy and CrZrTiNiCu coating were synthesized by mechanical alloying. It is shown that the microhardness of the CrZrTiNiCu coating is not inferior to and in most cases exceeds the hardness of high-entropy equiatomic alloys. The wear resistance of such a coating is 3·10^-4 g/min, which also corresponds to special steels in terms of wear resistance. The high-entropy coating has a low coefficient of friction. It turns out to be antifrictional, which obviously leads to energy savings. For the first time, the surface energy, contact potential difference and work function of electrons for CrZrTiNiCu coating were determined.

Abstract: One of the fundamental tasks in restoring the operability of cylinder liners is the application of a composite coating with a predetermined microhardness value. The authors have developed a technology for applying composite coatings based on iron on cylindrical surfaces, which makes it possible to vary the physical, mechanical and operational parameters of the formed iron-containing coating due to the planned selection of the deposition parameters. This eliminates the need for mechanical treatment of the applied coating, which is the reason for the high degree of rejection parts that undergo the iron-on operation. Contact interaction of the working tool with the formed layer of the composite coating has a positive effect on the value of its roughness.

Abstract: The article presents the assessment study of mechanical activation and mechanical alloying effect on the structure, phase state of the powder composition and of the coating based on it. The duration of mechanical activation was varied as follows: 1 h, 2 h, 4 h, 8 h, 16 h, 32 h. It is shown that in order to from a high-entropy FeNiCoAlNb alloy on the workpiece surface the duration of mechanical activation must be at least 4 hours. We described the mechanism of mechanical alloying and ways of accelerating this process.

Abstract: The technological process of thin-film sputtering significantly depends on the quality of the target for magnetron sputtering. This paper presents the features of obtaining the multicomponent magnetron target for the formation of non-porous transformation-hardenable coatings by the method of impact electric pulse consolidation. Special considerartion is given to the blend preparation and technological parameters of compaction. Blend powder consolidation under impact electric pulse compaction at different speeds of the striker has been investigated. At high speeds of the drop-hammer striker, the time parameters of the dynamic impact and electric pulse heating of the powder billet are shown to superpose, which leads to the final consolidation of the ceramic blend of the target for magnetron sputtering. The use of the technology of impact electric pulse compaction has made it possible to obtain multicomponent magnetron targets for formation of non-porous transformation-hardenable coatings of a given composition.

Abstract: It is shown that microarc oxidation (MAO) makes it possible to increase the size of aluminum alloy details by forming dense ceramic coatings (MAO-coatings) on them. Found that MAO-process a duration of 50...80 minutes in a liquid solution according to conventional technology allows you to increase the size of the details made of deformable alloy AMg3 and D16 by 78...80 % of the thickness formed on them MAO-coating and MAO-process in solution of corundum particles opens the possibility of increasing the same details by 98...100 % of the thickness formed on them more thick MAO coating. Revealed that increasing solution temperature from 15 to 45 оС leads to a reduction in the thickness of MAO coating and an even more significant reduction in growth dimensions, as well as to reduce the quality of their surfaces. It is shown that the removal of the outer layers of MAO coatings to a thickness of 20 ... 25 μm by grinding contributes to a significant reduction in the roughness of the surfaces of details. It is confirmed that MAO coatings obtained in liquid solution and in solution with corundum particles have a similar mainly polycrystalline structure, but MAO coatings obtained in solution with corundum particles differ in greater thickness and higher corundum content (α-Al₂O₃). It is established that the outer layers of MAO coatings are characterized by a relatively low content of modifications of crystalline aluminum oxide, so after their removal, the strength properties of the surfaces of details also improve. The principal possibility of increasing the size of details made of deformable aluminum alloys by 150 μm with ensuring high quality of their surfaces is proved.