Ultrafine-grained Al₂O₃−RE:YAG (RE=Ce; Ce+Gd) composite ceramics were obtained for the first time by reactive SPS using commercially available initial oxide powders. The effect of key sintering parameters (temperature and dwell time, external pressure) on densification peculiarities, structural-phase state, and luminescent properties of composites was studied comprehensively. Differences in phase formation and densification between Ce-doped and Ce,Gd-codoped systems were shown. Parameters of reactive SPS at which there is partial melting with the formation of near-eutectic zones of the Al₂O₃−YAG system/coexistence of several variations of the YAG-type phase were established. Pure corundum-garnet biphasic ceramics with an optimal balance between microstructural and luminescence performance were synthesized at 1425°C / 30 min / 30-60 MPa. The external quantum efficiency of the phosphor converters reached 80.7% and 72% with close lifetimes of ~63.8 nsec, similarly to commercial Ce:YAG materials, which is promising for further application in the field of high-power white LEDs and LDs.

Arc welding operations are considered to be risky procedures by generating hazardous welding fume for human health. This study focuses on the key characteristics, as well as dispersion models, of welding fumes within a work zone. Commercial and widely used types of electrodes with various types of covering (rutile, basic, acidic and rutile-cellulose) were used in a series of experiments on arc welding operations, under 100 and 150 amps of electric current. According to the results of this study, maximum levels of pollution with particles of PM₁₀ fraction occur in the workspace during arc welding operations. Disregarding the types of electrodes used, the 3D models of dispersion of the РМ₁₀ particles at the floor plane exhibit corrugated morphologies while also demonstrate high concentrations of the РМ₁₀ particles at distances 0–3 m and 4–5 m from the emission source. The morphology of these particles is represented by solid and hollow spheres, ‘nucleus-shell’ structures, perforated spheres, sharp-edged plates, agglomerates of the tree-like (coral) shape. At last the bifractional mechanism of fume particle formation for this type of electrodes is also shown and described. In this article results are reported, which demonstrate the hazards of the arc welding process for human health. The results of the characterization of WFs reported improve our understanding of risks that these operations pose to human health and may strengthen the need for their control and mitigation.