The Spectroscopy Net

Gateway

During the analysis process, each individual spark affects a different micro-surface. If the alloy is heterogeneous, measurements are scattered. When, before the measurement, the sample is subjected to high power discharges, a zone is melted which features a homogenous composition. This phase of the cycle is pre-integration. The standard deviation between several analyses may fall from 3% for measurements without pre-integration to 0.5% after pre-integration.

Further, some elements are contained in the analyzed metal in the form of molecules whose vaporization is different from that of unlinked elements. Melting of the sparking zone by pre-integration allows these compounds to be cracked.

As an example, steels 1, 2, 3, 4 and 5 contain increasing concentrations of manganese, and sample No. 4 further contains a high quantity of sulphur. If pre-integration is inadequate, the manganese, in the form of refractory sulphide in sample No. 4, is not dosed correctly. Thorough pre-integration destroys the sulphide and the points are aligned.

Author: Jean Charles Lefebvre, Jobin-Yvon Emission

First published on the web: 15 November 1999.

[ Previous ] [ Next ]