Corrosion of platinum alloy electrodes in a LiO2-Al2O3-SiO2 melt

摘要

Although platinum is known to be one of the most corrosion resistant metals, material degradation is observed when platinum alloy electrodes are in contact with glass melts. A glass melting furnace was set up in order to investigate the degradation mechanisms of platinum alloy electrodes in glass melts. This setup enables glass melting at temperatures up to 1700 degrees C and has two water cooled electrodes immersed into the melt with a maximum current of 10 A and variable current frequencies (0-6000 Hz). The well-known LiO2-Al2O3-SiO2 glass ceramic Ceran (R) was chosen for this work. The corroded platinum alloy electrodes were investigated using scanning electron microscope (SEM), energy dispersive x-ray spectroscopy (EDS), micro x-ray fluorescence analysis (mu RFA), diffractometry (XRD), and inductively coupled plasma-optical emission spectroscopy (ICP-OES). It was shown that above a threshold frequency platinum alloy degradation is very strongly reduced. The dependence of corrosion on current frequencies can be explained by jump distances of ions.