POTENTIAL OF A MICROWAVE BOOSTED GLOW-DISCHARGE SOURCE FOR THE ANALYSIS OF SILICON-CARBIDE POWDER

The microwave boosted glow discharge source has been investigated for its potential to analyse ceramic powders by atomic emission spectromet ry. SiC was used as an example. Electrically conducting samples were p repared by mixing the SiC-powder with copper powder and compressing th e mixture to pellets. Prior to the measurement the samples were heated to a temperature of 200 degrees C for 2 h to release molecular specie s adsorbed on the surface of the powders and to reduce the intensity o f molecular bands in the spectrum. The discharge was operated in argon as the plasma gas and boosted with 40 W microwave power. Argon pressu re and anode current were optimized to give the best line-to-backgroun d ratios. Crater shapes and erosion rates have been measured. The eros ion rates were found to be much lower in the pellets (23 nm s(-1)) tha n in bulk copper samples (63 nm s(-1)). Background equivalent concentr ations, measured for six elements in the pellets, are in the range of 0.1-6 mu g/g.