Untersuchungen zur Hochtemperaturchemie quecksilberfreier Metallhalogenid-Entladungslampen mit keramischem Brenner
The development of mercury-free metal halide lamps requires a modification of the burner vessel design and of the metal halide filling, compared to mercury-containing lamp types. Metal halides as NaI, TlI, DyI3 are added to discharge lamps in order to achieve a line-rich emission spectrum, resembling the sunlight. While evaporating, several chemical reactions occur among the inserted metal halides. Thus infecting the properties of light generation in a metal halide lamp. Further a corrosion attack on the burner vessel is observed due to chemical reactions of metal halides with the wall material Polycrystalline Alumina (PCA). In order to enhance the properties of light generation, it is aimed to describe the lamps in a thermodynamic model. Therefore statements on the light colour and the efficiency can be made. A complete thermodynamic data set of both gas and liquid phase reactions is required. Within the scope of the work in hand thermodynamic data for the formation of homo and hetero complexes as well as for chemical activities and excess enthalpies in metal halide systems were determined. A further reactive component is added to the chemical system of a metal halide lamp due to the mercury replacement Zn/ZnI2. Interactions between Zn/ZnI2 and metal halides cause the formation of new gas phase species, which were identified. Their influence on the properties of light generation and on corrosion was investigated. Therefore annealing experiments were conducted to elucidate the high-temperature corrosion of PCA. The observed corrosion phenomena were interpreted with respect to the principles of chemical transport. Model calculations using the beforehand determined data were accomplished to support the interpretation of the results, the annealing experiments obtained.
info:eu-repo/classification/ddc/620, Gasentladungslampe, Metallhalogenide, Chemische Reaktion, Leuchtdichte, Brenner <Feuerung>, Aluminiumoxidkeramik, Hochtemperaturkorrosion, Ingenieurwissenschaften, KEMS, Massenspektrometrie, Korrosion, Thermodynamik, Heterokomplexe, Aktivität
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