Characteristics of Aerosols Containing Chromium and Nickel From Some Thermal Spraying Operations

Characterization of aerosols, emitted from five methods of thermal spraying with materials containing chromium and nickel were carried out. The characterization procedure includes the determinations of the metal content, the particle size distribution, the oxidation state of chromium and a measure of the solubility of chromium. Three different kinds of samplers and the analytical methods PIXE (Particle Induced X-ray Emission analysis), ESCA (Electron Spectroscopy for Chemical Analysis), AAS (Atomic Absorption Spectrophotometry), spectrophotometry with DPC-reagent (sym-diphenylcarbazide), and TEM (‘Transmission Electron Microscopy) were used. The relative concentrations of the major elements in the aerosols agree with the relative abundances in the spraying material. A considerable part of the aerosol mass was found in the respirable fraction. Mass median aerodynamic diameters in the respirable fractions were below 0.5 µm. Hexavalent chromium, which is the oxidation state of chromium with the highest health hazard potential, was determined. Less soluble hexavalent chromium was detected in some of the spraying methods