Exchange of experience - Glow-discharge mass spectrometry, emission spectrometry, and x-ray fluorescence in compositional analysis of thermal-sprayed steel-based aluminum phosphate coatings

Phosphorus and trace impurities in aluminium phosphate powders and coatings are identified with glow-discharge mass spectrometry (GDMS), atom emission spectrometry (AES), x-ray fluorescence (XRF), and chemical analysis. Alumina powders with particles 60 to 40 mu m in size that are covered with Al(PO3)(3) and AlPO4 with TiO2 additives are sprayed using a supersonic air plasmatron. The distribution of elements across the coating on a steel substrate is examined with GDMS. The effect of polyatomic clusters is taken into account in determining Mg, P, S, and Ti by mathematical simulation. Phosphorus is identified with AES in a do air arc controlled to produce similar conditions for exciting PI lines in the evaporation of test and reference (Ca-3(PO4)(2)) samples. Comparing the results obtained by different methods shows that x-ray fluorescence reveals the. concentration from the surface of nucleus-shell particles. Measurements show that sonic part of phosphorus is lost in spraying because orthophosphates transform into metaphosphates.