Key Engineering Materials Vol. 743

Abstract: A method of arc surfacing with a consumable electrode and a flux-cored wire containing titanium nitride micro-and nanoparticles added to the weld pool was developed. The influence of the modifier on the structure and properties of the deposited coatings was studied.

Abstract: In the present study, the Raman spectra of diamond-like amorphous (a-C) and hydrogenated amorphous (a-C:H) carbon films on silicon obtained using the ion-beam methods and the pulse cathodic arc deposition technique were investigated with the aim of elucidating the relation between the hardness and structure of the films. The hardness of the samples used in the present study was 19 – 45 GPa. Hydrogenated carbon films were synthesized using END–Hall ion sources and a linear anode layer ion source (LIS) on single-crystal silicon substrates. The gas precursors were CH₄ and C₃H₈, and the rate of the gas flow fed into the ion source was 4.4 to 10 sccm. The ion energies ranged from 150 to 600 eV. a-C films were deposited onto Si substrates using the pulse cathodic arc deposition technique. The films obtained by the pulse arc technique contained elements with an ordered structure. In the films synthesized using low- (150 eV) and high-energy (600 eV) ions beams, an amorphous phase was the major phase. The significant blurriness of the diffraction rings in the electron diffraction patterns due to a large film thickness (180 – 250 nm) did not allow distinctly observing the signals from the elements with an ordered structure against the background of an amorphous phase.

Abstract: This article provides the reader with results of the study of mesostructure ordered plasma ceramic coatings derived from narrow-fraction powders under optimum modes for this fraction. It is noted that it is succeeded to implement mesostructure ordering of coatings eliminating the formation of continuous columnar structures by means of spraying mode control. It is proven that it is possible to get formation of nanocolumnar structures in a near surface layer, and these structures provide bonds damping between clusters under alternating force and thermal loads of coated parts. To evaluate the quality of formed ordered structure, a quantitative criterion—mesostructure ordering coefficient—is used. The Methods of quantitative evaluation of mesoordering of coating structure has been developed.

Abstract: The surface modification of microarc calcium phosphate coatings by boehmite nanoparticles deposition was studied. The powder of aluminium nitride AlN was deposited on the microarc calcium phosphate coatings, and then the hydrolysis reaction was initiated. The boehmite (AlO(OH)) was formed as a result of the reaction. The influence of boehmite nanoparticles deposition on the properties of calcium phosphate microarc coatings (i.e. the morphology, elemental and phase composition, wettability) was studied. Experimental results show that the introduction of boehmite nanoparticles affects the surface morphology and wettability of the coating.

Abstract: Cyclic voltammetry and potentiostatic polarization have been applied to study the electrochemical behavior and to determine the corrosion resistance of nitinol, which surface was modified with silicon using plasma-immersion ion implantation, in 0.9% NaCl solution and in artificial blood plasma. It was found out that continuous, and also homogeneous in composition, thin Si-containing layers are resistant to corrosion damage at high positive potentials in artificial physiological solutions due to the formation of stable passive films. Breakdown potential Eb of Si-modified NiTi depends on the character of silicon and Ni distribution at the alloy surface, Eb values amounted to 0.9–1.5 V (Ag/AgCl/KCl sat.) for the alloy samples with continuous Si-containing surface layers and with decreased Ni surface concentration.

Abstract: Corrosion protection of equipment, apparatus and thermal-stressed metal structures (which refer to equipment of fuel and power industries) operated under conditions of chemical manufacturing processes is the prime industrial target. Corrosive medium causes changes in material structure and properties resulting in decreased strength and premature damage of equipment [1].The subject of research is the system of thermal resistant protective coating for extreme operation conditions.The objective of the study is technology development of protective organic coating with predictable properties within the long-term operation of real gas-compressor units. The research resulted in improved procedure of thermogradient coatings application with positive progress due to the modification of layers of heat-resistant paintwork materials [2].

Abstract: The paper presents a non-isothermal model of the initial stage of ion implantation process. The model takes into account the existence of internal interfaces. The model assumes that the implantable impurity generates mechanical perturbations. These disturbances can propagate at different speeds before and after internal boundary. The examples of the waveform evolution in transition across the border are shown.

Abstract: In this article, SPH and MLSM methods are compared in application to particle impact modelling. It is shown, that both methods has important disadvantages because nonzero acceleration appears in the case of constant stress field with nonsymmetrical distribution of nodes in space. Some reasons of incorrect acceleration calculation are discussed.

Abstract: Treatment of hypereutectic structure silumin (18-24 wt% of Si) by an intense pulsed electron beam of submillisecond duration is carried out. Formation of submicro- and nanocrystalline structure in the surface layer is revealed, which is caused by ultrahigh (up to 10⁸ K/s) cooling rates of the melted layer. It is established that the modification of the silumin surface layer by an electron beam increases its hardness by 5 times.

Abstract: In this paper, the direct boundary element method in the Laplace domain is applied for the solution of three-dimensional transient dynamic problems of anisotropic elasticity in multi-connected domains. The formulation is based upon the integral representations of anisotropic dynamic fundamental solutions. As numerical example the problem of an anisotropic elastic prismatic solid with cubic cavity is investigated.