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The influence of the beam current, the distance between the beads of the clad material and the wire feeding intensity during electron‑beam (EB) surfacing of titanium alloy VT9 on the thickness and uniformity of the resulting restoring coating was investigated. As the beam current strength increases, the width of the deposited layer increases and the height decreases. The optimal distance between the beads should be considered an offset that does not exceed the width of the bead. It is possible to control the height of the deposited layer in a wide range by precise dosing of the wire feed intensity. The uniformity of surfacing is ensured by a balanced energy impact. Chemical composition of the clad layer meets the requirements of normative documents on the content of impurity gases for products from medical materials, obtained by additive technologies. The results of the study are used in the restoration of the surface of the landing gear element of aviation equipment.

In modern conditions of economic instability in various sectors of industry for the national economic complex, it is important to improve the technology for repairing parts of power units, while the development of modern technological methods for restoring the contact surfaces of parts should be carried out in the conditions of enterprises and be accessible. The article compares the most common methods of surface parts restoration, such as flame, plasma spraying and electric arc surfacing. Studied experience of various specialists working in this direction made it possible to implement these reduction methods using a charge based on a mineral tungsten-containing concentrate, boron and carbon. The process of alloying the resulting coatings was investigated, where tungsten is in the form of tungsten trioxide (WO3) and calcium tungstate (CaWO4). A comparative analysis of the methods for restoring the surface of the exhaust valve cone of the D49 diesel engine has been carried out. The article presents results of microand macroanalysis of the structures of the obtained coatings and the base metal of the restored part, the results of the analysis of the chemical composition, the evaluation of the microhardness and adhesive strength of the adhesion of the obtained coatings to the surface of the base metal. Authors substantiated the prospect of applying the methods of gas-thermal restoration of the surface of parts in relation to the method of electric arc surfacing. Subsequent studies will focus on the installation of remanufactured parts in the internal combustion engine of the locomotive, their operation in real conditions, and the assessment of reliability and durability. Research in this direction will improve the quality indicators of the restored surfaces of power unit parts of rolling stock.

Abstract—Restoration of the spherical surface of a steel 35L cone housing by mechanized surfacing in protective gas is proposed. The method employed does not involve heating of the part before or in the course of surfacing. The coating produced has the required thickness and chemical composition, with specified structure. The coating is strongly bound to the restored surface and is free of pores and cracks. [ABSTRACT FROM AUTHOR]

One challenge in surface restoration is to design surface diffusion preserving ridges and sharp corners. In this paper, we propose a new surface restoration model based on the observation that surfaces' implicit representations are continuous functions whose first order derivatives have discontinuities at ridges and sharp corners. Regularized by vectorial total variation on the derivatives of surfaces' implicit representation functions, the proposed model has ridge and corner preserving properties validated by numerical experiments. To solve the proposed fourth order and convex problem efficiently, we further design a numerical algorithm based on the augmented Lagrangian method. Moreover, the theoretical convergence analysis of the proposed algorithm is also provided. To demonstrate the efficiency and robustness of the proposed method, we show restoration results on several different surfaces and also conduct comparisons with the mean curvature flow method and the nonlocal mean method. [ABSTRACT FROM AUTHOR]

Core-shell structure is an obvious concept to suppress surface-related deactivations in lanthanide-doped upconversion nanoparticles (UCNPs). However, no direct observation of atomic-scale surface restoration, which can improve the upconversion photoluminescence, has been reported. Here, we use aberration-corrected high-angle annular dark field scanning transmission electron microscopy to study the surface condition of KLu 2 F 7 :Yb 3+ ,Er 3+ bare core UCNPs. Due to the very thin and uniform thickness of the UCNPs, we observe unambiguously that the recovery from surface defects enhances upconversion photoluminescence. Furthermore, the realization of dominant green lasing emission under pulsed laser excitation confirms the high crystallinity of the UCNPs.

The final installment in this three-part series focuses on the main features of the NTSP online tutorials for image and surface restoration. [ABSTRACT FROM PUBLISHER]