Heiko Hessenkemper

Influence of glass basicity on redox interactions of iron-manganese-copper ion pairs in soda-lime-silica glass

The redox interactions of iron, manganese, and copper ion pairs including absorption characteristics in a multicomponent soda-lime-silica glass, were investigated. Glasses containing 11–19 mol % Na2O were melted under an air atmosphere in an electric furnace at 1450°C for 8 h. The results of chemical analysis indicated that the redox pairs of Fe2+/Fe3+, Mn2+/Mn3+, and Cu+/Cu2+ shift to more oxidized states as a function of increasing glass basicity. The redox interactions of individual pairs, e.g., Fe2+/Fe3+-Mn2+/Mn3+, Fe2+/Fe3+-Cu+/Cu2+, and Mn2+/Mn3+-Cu+/Cu2+, were not strong but changed with glass basicity. For the three redox pairs, Fe2+/Fe3+-Mn2+/Mn3+-Cu+/Cu2+, both Mn3+ and Cu2+ ions simultaneously and proportionally oxidized Fe2+ to Fe3+ and did not affect one another. The reaction constants log Q2 of Fe2+/Fe3+-Mn2+/Mn3+ and Mn2+/Mn3+-Cu+/Cu2+ redox pairs decreased while the Fe2+/Fe3+-Cu+/Cu2+ and three redox pairs systems changed markedly with increasing the glass basicity. The oxidizing and reducing powers of each ion changed only slightly in the present of one another, and the absorption spectra of all the single polyvalent elements confirmed to the Lambert-Beer law. The spectra depended directly on the concentrations of each absorbing ion. While the spectra of glass doped with more than one element confirmed the direction of the equilibrium shift, they were used only to predict the degree of interaction. These investigations gave consistent results.

Study of the Structures and Physical Properties of Calcium Borophosphate Glass Containing Transition Metal Oxides

This research objected to study the effects of CeO2, Sb2O3 and CoO on the structures and properties of calcium borophosphate glass (CBF) in ternary system 0.42CaO-0.06B2O3-0.52P2O5. The batches were melted at 1200 °C with 5 °C /min for 1 h in an electric furnace. The melts were regular bulk formed by pouring into a stainless mold and were immediately transferred to an annealing lehr at 550 °C for 2 h for testing the properties. The structures and physical properties were investigated. The results showed that all doped CBF glass were completely melted representing only one broad peak in XRD patterns. The structural observations revealed the major units are cross-linking B-O-P and B-O-B triangle and B-O-B tetrahedral units. The dense packing of structural or the shorter phosphate chain length and whether the branching group were achieved as the series CeO2>Sb2O3>CoO. The density, refractive index, glossy, Abbe number increased slightly with increasing of transition oxide concentrations as the series CeO2>Sb2O3>CoO. The microhardness also increased with increasing the concentration of transition oxides as the series CeO2

Envisioning Improvement in the Radiative Heat Transfer and Service Life of the Silica Crown in Glass Furnaces

The corrosion of the silica crown in the glass furnace is still a problem which does not enable a higher temperature of the superstructure. So the aim of this study was to transfer the developed surface treatment technology of ancorro to the superstructure of the furnace. Also a higher radiative heat transfer by changing the emissivity of the refractory should be realized. The corrosion tests were done with NaOH at 1200°C and 1500°C. After treating the silica material the service life increases up to 25%. To detect the corrosion attack of the bricks a 3D scanner was used for the measurement. After the surface treatment of the bricks the modified radiative heat transfer was measured by using an IR camera. The results were used for modeling a glass furnace with modified heat transfer by the silica crown. In comparison to experience and measured data from glass industry huge energy savings are possible.