Solid-State Welding of the Nanostructured Ferritic Alloy 14YWT Using a Capacitive Discharge Resistance Welding Technique

Joining nanostructured ferritic alloys (NFAs) has proved challenging, as the nano-oxides that provide superior strength, creep resistance, and radiation tolerance at high temperatures tend to agglomerate, redistribute, and coarsen during conventional fusion welding. In this study, capacitive discharge resistance welding (CDRW)—a solid-state variant of resistance welding—was used to join end caps and thin-walled cladding tubes of the NFA 14YWT. The resulting solid-state joints were found to be hermetically sealed and were characterized across the weld region using electron microscopy (macroscopic, microscopic, and nanometer scales) and nanoindentation. Microstructural evolution near the weld line was limited to narrow (~50–200 μm) thermo-mechanically affected zones (TMAZs) and to a reduction in pre-existing component textures. Dispersoid populations (i.e., nano-oxides and larger oxide particles) appeared unchanged by all but the highest energy and power CDRW condition, with this extreme producing only minor nano-oxide coarsening (~2 nm → ~5 nm Ø). Despite a minimal microstructural change, the TMAZs were found to be ~10% softer than the surrounding base material. These findings are considered in terms of past solid-state welding (SSW) efforts—cladding applications and NFA-like materials in particular—and in terms of strengthening mechanisms in NFAs and the potential impacts of localized temperature–strain conditions during SSW.

Impact of the plasma flow of a low-pressure high-frequency capacitive discharge on the adhesive and physical and mechanical characteristics of aramid and carbon fibers

The changes in the adhesive and physico-mechanical characteristics of aramid and carbon fibers treated with plasma of a highfrequency capacitive gas discharge of reduced pressure are considered. An increase of ~ 30% in the wettability of the surface of aramid and carbon fibers is shown. It was found that the strength of plastics made on the basis of aramid and carbon fibers treated with a plasma flow increases by ~ 26%.

ON THE EFFECT OF A GAS DISCHARGE ON THE PROPERTIES OF JUTE

The article considers the influence of high-frequency capacitive discharge on the mechanical proper-ties of jute fibres and jute fabrics. The surface changes of jute fibres were studied by scanning electron atomic force microscopy. The authors noted that after exposure to a gas discharge on the fibres, there is a smoothing of the relief boundaries, and the products of etching of the fibre surface are also visible; when etching in the air, destructed areas appear, the surface is damaged and becomes inhomogeneous. An increase in the strength of jute fibres during modification in reactive and inert gases was revealed. During the experiments, it was found that the strength of the samples of jute fibres treated in the high-frequency capacitive discharge in the argon and nitrogen medium is higher than the original fibre samples by an average of 23 %. According to experimental data, an increase in the breaking load of jute fabrics was found to be up to 20% on average. The use of plasma modification at the stage of preparation of jute fibres for carding processes is recommended.