Conversion kinetics of container glass batch melting

Understanding the batch-to-glass conversion process is fundamental to optimizing the performance of glass-melting furnaces and ensuring that furnace modeling can correctly predict the observed outcome when batch materials or furnace conditions change. To investigate the kinetics of silica dissolution, gas evolution, and primary foam formation and collapse, we performed X-ray diffraction, thermal gravimetry, feed expansion tests, and evolved gas analysis of batch samples heated at several constant heating rates. We found that gas evolving reactions, foaming, and silica dissolution depend on the thermal history of the batch in a similar manner: the kinetic parameters of each process were linear functions of the square root of the heating rate. This kinetic similarity reflects the stronger-than-expected interdependence of these processes. On the basis of our results, we suggest that changes in furnace operating conditions, such as firing or boosting, influence the melting rate less than what one would expect without consideration of batch conversion kinetics.     

Influence of addition of nanosize barium cerate on the microstructure and properties of top-seeded melt growth YBCO bulk superconductors

Barium cerate (BaCeO₃) is one of the possible additions to bulk YBa₂Cu₃O₇ single-grain superconductors to suppress the growth of Y₂BaCuO₅ (Y211) particles. This paper investigates the synthesis of barium cerate powder and its use in YBa₂Cu₃O₇ bulk superconductors. Crystalline barium cerate was synthesized by solid-state reaction, by co-precipitation of oxalates and by sol-gel method. Final calcination was held in air or in vacuum. It is shown that the most efficient in refining Y211 is nanocrystalline barium cerate prepared by sol-gel method calcined in vacuum. The effective refinement of Y211 particles occurred over the entire interval of nanocrystalline BaCeO₃ addition from 0.38 to 1.90 wt%. The optimal concentration of nanosize barium cerate was determined, microstructure and superconducting properties were characterized. The effect of Y211 content on trapped field in YBCO bulks with addition of nanocrystalline barium cerate is shown.     

Low-temperature phase formation in the SrF2–LaF3 system

Phase formation in the SrF₂–LaF₃ system was studied at temperatures ranging from 300°C to 450°C using nitrate flux. The solubility of LaF₃ in SrF₂ decreases with decreasing temperature. The equilibrium width of the solid solution region Sr_1−xLa_xF_2+x at 400°C, it is 44.6 ± 0.4 mol% LaF₃ (x = 0.446), at 350°C — 38.3 ± 0.7 mol% LaF₃ (x = 0.383), and decreases almost to zero at 300°C.     

Effect of composition on the matrix transformation of the Co-Re-Cr-Ta-C alloys

Neutron diffraction measurement was performed in-situ at high temperatures on Co-Re-Ta-C alloys with and without Cr addition. This included alloys containing different C content with the C/Ta ratio varying between 0.5 and 1.0. The Co-Re-solid solution matrix of the experimental alloys is polymorphic (like in pure cobalt) and transformed from low temperature hexagonal ? phase to high temperature cubic γ phase on heating. This transformation is reversible and show hysteresis. The main alloying addition, Re, stabilizes the ? Co-phase and increases the transformation temperature to above 1273 K. The onset of the \(\varepsilon \rightleftharpoons \gamma\) transformation during heating and cooling was found to differ depending on the alloy composition. In alloys without Cr addition the transformation was not completed on cooling and the high temperature γ phase was partly retained at room temperature in metastable state with the amount depending on the cooling rate from high temperature. The diffraction and microstructural results showed that Cr is ? stabilizer (similar as Re) but the role of Ta is not clear. The C/Ta ratio has no direct effect on the matrix phase transformation. Nevertheless, it influences indirectly by determining the amount of Ta which is freely available in the matrix.     

Matrix Transformation in Boron Containing High-Temperature Co–Re–Cr Alloys

An addition of boron largely increases the ductility in polycrystalline high-temperature Co–Re alloys. Therefore, the effect of boron on the alloy structural characteristics is of high importance for the stability of the matrix at operational temperatures. Volume fractions of ε (hexagonal close-packed—hcp), γ (face-centered cubic—fcc) and σ (Cr₂Re₃ type) phases were measured at ambient and high temperatures (up to 1500 °C) for a boron-containing Co–17Re–23Cr alloy using neutron diffraction. The matrix phase undergoes an allotropic transformation from ε to γ structure at high temperatures, similar to pure cobalt and to the previously investigated, more complex Co–17Re–23Cr–1.2Ta–2.6C alloy. It was determined in this study that the transformation temperature depends on the boron content (0–1000 wt. ppm). Nevertheless, the transformation temperature did not change monotonically with the increase in the boron content but reached a minimum at approximately 200 ppm of boron. A probable reason is the interplay between the amount of boron in the matrix and the amount of σ phase, which binds hcp-stabilizing elements (Cr and Re). Moreover, borides were identified in alloys with high boron content.     

Some Properties of Nickel-Cobalt Alloys Electrodeposited from Sulphosalicylate Solutions

An uncommon electrolyte, based on sulphosalicylic acid, was used for nickel-cobalt deposition. Some mechanical properties (internal stress and microhardness) and structural properties of the deposits have been presented. High microhardness (nearly 800 HM) with simultaneous low internal stress (about 50 MPa) can be reached.     

Sex-Related Differences in Murine Models of Chemically Induced Pulmonary Fibrosis

We developed two models of chemically induced chronic lung injury and pulmonary fibrosis in mice (intratracheally administered hydrochloric acid (HCl) and intratracheally administered nitrogen mustard (NM)) and investigated male–female differences. Female mice exhibited higher 30-day survival and less weight loss than male mice. Thirty days after the instillation of either HCl or NM, bronchoalveolar lavage fluid displayed a persistent, mild inflammatory response, but with higher white blood cell numbers and total protein content in males vs. females. Furthermore, females exhibited less collagen deposition, milder pulmonary fibrosis, and lower Ashcroft scores. After instillation of either HCl or NM, all animals displayed increased values of phosphorylated (activated) Heat Shock Protein 90, which plays a crucial role in the alveolar wound-healing processes; however, females presented lower activation of both transforming growth factor-β (TGF-β) signaling pathways: ERK and SMAD. We propose that female mice are protected from chronic complications of a single exposure to either HCl or NM through a lesser activation of TGF-β and downstream signaling. The understanding of the molecular mechanisms that confer a protective effect in females could help develop new, gender-specific therapeutics for IPF.     

A comparative study of direct and indirect evaluation of piezoelectric properties of electrophoreticaly deposited (Ba,Ca) (Zr,Ti)O3 lead-free piezoceramics

The development and optimisation of piezoceramics are targeted usually to enhance their piezoelectric properties evaluated by both the direct or indirect measurement methods. The presented work aims to elaborate on the correlation of one direct (Berlincourt) and two indirect (convert and field-dependent) piezoelectric measurement methods on various material states. The role of the ceramic powder treatment by ball milling and electrophoretic deposition (EPD) technique on the determined electric properties as well as basic physical and mechanical properties of (Ba_0.85Ca_0.15) (Zr_0.1Ti_0.9)O₃ ceramics (BCZT) was investigated. It was found that the EPD technologically supported by milling allows obtaining thick and dense deposits (>2 mm). After sintering, the BCZT ceramics with a relative density of >95%, hardness in the range of 2.3–2.9 GPa and piezoelectric coefficients of d₃₃* = 940 pm/V, d_33(E=0) = 427 pm/V and d₃₃ = 364 pC/N can be achieved. Reported results also suggest that indirect (field-dependent) and direct (Berlincourt) measurements of the piezoelectric coefficients can be comparable at optimal poling conditions.