Effects of atomization surfaces and modifiers on the electrothermal atomization of cadmium

Atomization of cadmium on tungsten carbide, molybdenum carbide and metallic palladium coated platforms and on pyrolytic graphite coated platforms with and without tungsten, molybdenum and palladium modifiers has been studied. A physical vapour deposition method is used for coating. A high thermal stability, a greater appearance temperature and a decrease in sensitivity are found when compared with atomization on conventional platforms. Diffusion and kinetic parameters are obtained using different models. More than one activation energy (E(a),) and frequency factor (nu) are obtained depending on the atomization temperature while the atomic vapour appears. These results may indicate that more than one formation process is simultaneously present or that the evolution from one formation process to another is temperature dependent. Greater values of E(a) and nu are found during atomization on the molybdenum carbide coated platform and when molybdenum or palladium modifiers are used. This may suggest that strong cadmium-metal interaction is present. This strong interaction is not present when palladium is used as a metallic coating, although a similar trend in thermal stability is observed. The contribution of the expansion to the atomic vapour dissipation is also evaluated.