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Considered are the prospects of applying complex post-processing for an additive manufactured product with the deposition of a multilayer composite coating [Ti0.2C0.8/a-C]40 at the final stage. It is shown that heat treatment, finish milling, ion-plasma nitriding and burnishing with a sliding diamond indenter of a PH1 steel part obtained by selective laser melting (SLM) before deposition of a thin-film coating provides the coating with a minimum surface roughness Ra = 82-86 nm and a maximum hardness of 25.2 ± 1.4 GPa with an increase in the microhardness of the entire “coating-substrate” system. © 2021 Institute of Physics Publishing. All rights reserved. The research was funded by RFBR for Basic Research and Sverdlovsk Oblast (project No. 20-48-660065) and partially carried out within the state assignment for IMP UB RAS, theme “Structure” No. AAAA-A18-118020190116-6. The authors express particular gratitude to A.G. Merkushev and I.Y. Malygina for their participation in the work.

1 M solutions of NaClO4 mixed with ethylene carbonate, dimethyl carbonate, and fluoroethylene carbonate were studied as electrolytes for a double-layer supercapacitor with electrodes made of Norit DLC Supra 30 activated carbon. It was shown that the specific capacity of activated carbon depends on the electrolyte composition, range of cycling voltages, and current density. The maximum specific capacitance of 40 F g–1 was obtained in 1 M NaClO4 mixed with ethylene carbonate: dimethyl carbonate: fluoroethylene carbonate (4: 5: 1) at a current density of 36 mA g–1 in the range 10–2300 mV. The minimum specific capacitance was obtained under the same cycling conditions in the electrolyte with 1 M NaClO4 + ethylene carbonate: dimethyl carbonate (1: 1). The variation of the specific capacitance with the electrolyte composition and range of cycling voltages is accounted for by the existence of a pseudocapacitance caused by the occurrence of side processes on the surface of activated carbon. The impedance spectroscopy was used to find that the introduction of fluoroethylene carbonate into the electrolyte positively affects the charge-transfer resistance and favors an increase in the specific capacitance of activated carbon.

[Ti0.2C0.8/a-C]40 multilayer thin films composed of forty pairs of TiC and pure carbon layers were formed on a selective laser melted (SLM) martensitic stainless steel by means of ion-plasma deposition process. SLM steel was pre-treated by one of the two following schemes: (1) oil quenching from 1040°C followed by heating to 480°C for 4 hours and air cooling (HT), finish milling (FM); (2) HT, FM, ion-plasma nitriding followed by burnishing. Mechanical failure mode and critical load Lc for damaging the coatings were determined using linear scratch tests performed at linearly-increased normal force. Indentation by conical diamond tip were carried out in order to asses an elastic recovery and energy dissipation coefficient defined as the ratio of plastic to total deformation energy. The scratch test results showed that the post-processing of the substrate strongly influenced the failure mode of the coating and increased the critical load from 320 mN to 920 mN. Indentation revealed that nitriding and burnishing before coating deposition increase the elastic recovery of the [Ti0.2C0.8/a-C]40 coating-substrate system from 24% to 68%. The energy dissipation coefficient drops from 79% to 45%.

The structure and micromechanical properties of a 316L stainless steel produced by the selective laser melting (SLM) technique have been studied in its initial state and the following heat treatment: quenching from 1050 ºС and 4-hour annealing at 480 ºС. The heat treatment does not result in changing the steel phase composition, however, it reduces the microhardness by 5%, HM hardness (Martens hardness) by 12% and indentation hardness by 16% at HIT maximum load. The heat treatment also increases the Е* contact elasticity modulus by 14% due to the lower porosity of the material. As soon as heat treatment provides no strengthening of the steel synthesized by SLM, deformation processing, chemicothermal treatment and application of thin coatings may become quite promising strengthening methods. © 2020 Institute of Physics Publishing. All rights reserved. The main results were funded by the RFBR and Sverdlovsk Oblast, project number 20-48-660065. The results of the electron diffraction phase analysis were obtained by the M.N. Mikheev Institute of Metal Physics of the Ural Branch of the Russian Academy of Sciences (IMP UB RAS) within the state assignment of Ministry of Science and Higher Education of the Russian Federation (theme “Structure” No. № АААА-А18-118020190116-6). The studies were performed at the collaborative access center “Testing center of nanotechnology and advanced materials” of IMP UB RAS.

The specific characteristics of natural pyrite (FeS2) are investigated using a galvanostatic cycling method. The investigation is carried out for electrolytes consisting of dimethylcarbonate (DMC) and a lithium salt (LiBF4, LiClO4, or LiN(CF3SO2)2). It is shown that the specific capacitance of FeS2 and its stability during cycling depend on the concentration and the nature of a lithium salt anion. The greatest efficiency of the galvanostatic cycling of FeS2 is achieved for the DMC-LiClO4 and DMC-LiN(CF3SO2)2 electrolytes in salt concentrations in the range of 0.1–0.2 molar fractions.

The electrochemical characteristics of natural pyrite FeS2 in electrolytes based on salt-solvate mixtures (lithium bis(trifluoromethane)sulfonamide and linear ethers) have been investigated. The specific capacity (Q) of natural pyrite during cycling within the temperature range of 20–80°C has been estimated. It has been shown that, at room temperature, the Q value for FeS2 depends on the concentration of lithium salt and on the linear ether nature. In diluted solutions, the specific capacity values are close and do not depend on the nature of the linear ether. In salt-solvate electrolytes, the specific capacity varies in the following range: monoglyme (MG) > tetraglyme (TG) > diglyme (DG), which is apparently due to the conductivity, which reduces in a similar sequence. The higher the temperature, the higher the discharge capacity of pyrite. It is typical for both the first cycle and the cycling as a whole. The specific capacity values of FeS2 at 60°C in DG (0.44 LiImid) and TG (0.5 LiImid) electrolytes appear to be almost equal and correspond to about 500 mA h/g. It is shown that the “open circuit voltage-introduced lithium amount” dependence does not differ significantly in diluted and salt-solvate electrolytes during the first cycle. However, the difference becomes more apparent during cycling of FeS2.

Using transmission electron microscopy, Mossbauer spectroscopy, and measurements of hardness, the carbide precipitation during tempering of steel X153CrMoV12 containing (mass pct) 1.55C, 11.90Cr, 0.70V, and 0.86Mo is studied after three treatments: quenching at RT and deep cryogenic treatment, DCT, at 77 K or 123 K (−196 °C or −150 °C). In contrast to some previous studies, no fine carbide precipitation after long-time holding at cryogenic temperatures is detected. After quenching at room temperature, RT, the transient e(e′) carbide is precipitated between 373 K and 473 K (100 °C and 200 °C) and transformed to cementite starting from 573 K (300 °C). In case of DCT at 123 K (−150 °C), only fine cementite particles are detected after tempering at 373 K (200 °C) with their delayed coarsening at higher temperatures. Dissolution of cementite and precipitation of alloying element carbides proceed at 773 K (500 °C) after quenching at RT, although some undissolved cementite plates can also be observed. After DCT at 123 K (−150 °C), the transient e(e′) carbide is not precipitated during tempering, which is attributed to the intensive isothermal martensitic transformation accompanied by plastic deformation. In this case, cementite is the only carbide phase precipitated in the temperature range of 573 K to 773 K (300 °C to 500 °C). If DCT is carried out at 77 K (−196 °C), the e(e′) carbide is found after tempering at 373 K to 473 K (100 °C to 200 °C). Coarse cementite particles and the absence of alloying element carbides constitute a feature of steel subjected to DCT and tempering at 773 K (500 °C). As a result, a decreased secondary hardness is obtained in comparison with the steel quenched at RT. According to Mossbauer studies, the structure after DCT and tempering at 773 K (500 °C) is characterized by the decreased fraction of the retained austenite and clustering of alloying elements in the α solid solution. It is suggested that a competition between the strain-induced transformation of the retained austenite and carbide precipitation during the wear can control the life of steel tools.

The tool steel X220CrVMo 13-4 (DIN 1.2380) containing (mass%) 2.2C, 13Cr, 4V, 1Mo and the binary alloy Fe–2.03 mass% C were studied using transmission electron microscopy, Mossbauer spectroscopy, X-ray diffraction and internal friction with the aim of shedding light on processes occurring during deep cryogenic treatment. It is shown that the carbon atoms are essentially immobile at temperatures below −50 °C, whereas carbon clustering in the virgin martensite occurs during heating above this temperature. An increase in the density of dislocations, the capture of immobile carbon atoms by moving dislocations, the strain-induced partial dissolution of the carbide phase, and the abnormally low tetragonality of the virgin martensite are found and interpreted in terms of plastic deformation that occurs during martensitic transformation at low temperatures where the virgin martensite is sufficiently ductile.