MASS-SPECTROMETRIC INVESTIGATIONS OF ALUMINUM-OXIDE REDUCTION BY GASEOUS ALUMINUM CARBIDES IN ELECTROTHERMAL ATOMIZATION

Inducement of free atom formation by reduction of oxide by carbides (ROC) was investigated experimentally using mass spectrometric techniques. The effort focuses on atomization of Al2O3 using aqueous, slurry and solitary Al-sphere samples to evaluate the ROC model. Conventional heating rates as well as the low heating rates used to evaluate the "spike" phenomenon, show relatively little Al2C2 produced during free atom formation. The more abundant, consistently observed, gaseous species were Al, Al2, and unless Al-sphere samples were used, Al2O. These were also the more abundant species contained in the "spike" profiles. The spike phenomenon is observed even for the metal samples. The observations are not attributable to an ROC mechanism as presently conceived.