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Institute of Energy and Climate Research (IEK)

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Corrosion and Wetting Studies for Increasing the
Lifetimes of High-Intensity Discharge Lamps


High-intensity discharge lamps are an alternative to incandescent lamps, both in energetic and in economic terms. They are characterized by a high luminosity and a very high colour rendering index. For these reasons, high-intensity discharge lamps are used by the film industry for lighting sets, for example, or in football stadiums.

This research project studies metal halide discharge lamps. These lamps often contain metal iodides, which, in a plasma, emit light according to their characteristic spectra. Inside the lamp burner, a plasma is created between two tungsten electrodes at a temperature of 6000 °C. By adjusting the metal iodide mixture, a colour spectrum can be developed that users consider to be comfortable.

The substances used to fill high-intensity discharge lamps can, however, have a negative impact on their lifetime. The contact of molten metal halides with the burner walls can cause corrosion. These corrosion effects are influenced by the wetting properties of the molten metal halides on the walls.

This is the reason why Materials Chemistry studies the thermodynamic properties of metal iodide mixtures relevant for these lamps as part of this research project. The goal is to develop a new generation of energy-saving lamps with a comfortable colour temperature and longer lifetimes. The wetting properties are examined using a contact angle measurement facility, while the corrosion of the burner wall is measured by means of exposure tests. In order to simulate the lifetime and understand the reactions in the burner, thermodynamic data are determined using Knudsen effusion mass spectrometry.

Discharge lampsDischarge lamps

Corroded polycrystalline aluminaCorroded polycrystalline alumina