METHOD OF DETERMINING THE CONCENTRATIONS IN UNDISSOLVED AND PRECIPITATED STATES OF AN ELEMENT SUCH AS ALUMINIUM IN A METALLIC SAMPLE BY WAY OF OPTICAL EMISSION SPECTROMETRY, AND APPARATUS FOR CARRYING OUT SUCH A METHOD

摘要

1. A process for determining the dissolved and precipitated concentrations of an element, such as aluminum, in a metallic analysis sample (4) by Optical Emission Spectrometry, in particular a steel sample, comprising the steps of determining said concentrations on the basis of the spark erosion profile in time (18) of said element and reading on calibrating charts set for known samples, characterized by the steps of - submitting the sample (4) to mild spark erosion conditions for the entire duration of the analysis in such a way as to avoid any phenomenon of local refusion of the sample ; - dividing the spark erosion profile (18) thus obtained for the element under analysis into at least two successive parts : an initial part formed by a peak (19) and a terminal part formed by a horizontal flat portion (20) ; - considering a standardized value I3 of the intensity of the complete spark erosion profile and determining on the basis of I3 the total concentration [M]t of the element under analysis by reading on the corresponding calibrating chart constructed on the basis of said standardized value, - considering a standardized value I2 of the intensity of the horizontal flat portion (20) and determining on the basis of I2 the concentration in the dissolved state [M]d of the element under analysis by reading on the corresponding calibrating chart constructed on the basis of said standardized value ; - and calculating on the basis of the values I3 and I2 and of the total concentration [M]t the concentration in the precipitated state [M]p of the element under analysis with the aid of the relation : [M]p =[M]t J-I2 /I3 -I0 wherein I0 is the value at the origin of the intensity on the calibrating chart giving the total concentration [M]t and J is the standardized value of an intensity of the spark erosion profile representative of the sum of concentrations in the dissolved and precipitated states of the element under analysis.