X-ray Fluorescence Spectrometric Determination of Microamounts of Sulfur in Iron and Steel by the Glass Bead Sample Technique

Abstract

An X-ray fluorescence spectrometric method was developed for the determination of microamounts of sulfur in iron and steel.
Sulfur was separated as barium sulfate based on a conventional gravimetric method and then instead of weighing the precipitate the X-ray fluorescence analysis using a glass bead technique was applied to improve the precision and accuracy in the barium sulfate method.
The outline of the method is as follows:
Five grams of a sample are dissolved in nitric and hydrochloric acids. The solution is evaporated to dryness, the salts are dissolved in hydrochloric acid, and metallic zinc is added to reduce ferric ions to ferrous ions. After adjusting the acidity, barium sulfate is precipitated as usual. The filtered precipitate is dried, heated, and fused with 5 g of sodium tetraborate in a Pt-Au-Rh crucible to prepare a glass bead. The X-ray fluorescence intensity of Ba Lα is measured on the bottom surface of the bead and is converted to the sulfur content. Calibration standard beads are prepared from pure barium sulfate synthesized from sulfuric acid and barium chloride.
The proposed method was applied to JSS standard carbon steels and satisfactory results were obtained. With some modifications in the sample treatment procedure the method was also applicable to steel making iron and stainless steel. The method gives accurate results for sulfur down to 0.001% and is useful as a standard method for the determination of sulfur in iron and steel.