Comparative bulk, surface and depth profile analyses on AlN and SiC-coated B4C powders

Summary On thin layers of m sized AIN particles, superficial enrichment of O, probably caused by atmospheric hydrolysis and/or oxidation, was detected by means of Auger Electron Spectroscopy (AES) combined with sputter depth profiling. By comparing the O/N ratio found at the surface with that of the bulk, determined by means of the carrier gas heat extraction (CGHE) method, surface enrichment appeared to be more pronounced for lower O coverages. Chemical speciation of O (H₂O, CO₂) was feasible using appropriate CGHE techniques. — Similarly, using AES and Secondary Ion Mass Spectrometry as depth profiling methods, surface enrichment of Si, C and O was found for two B₄C powders, which had been coated by the sintering additive SiC. For this system, Laser Mass Microanalysis yielded additional information about chemical species. Combination of all applied methods led to comprehensive models of the natural and prepared particle coatings.