Ig. Cobo et al., REMELTING TECHNIQUE FOR X-RAY-FLUORESCENCE ANALYSIS OF MAIN CONSTITUENT IN FERROMOLYBDENUM AND FERRONIOBIUM, Journal of trace and microprobe techniques, 13(4), 1995, pp. 431-441
A study was conducted of the main constituent determination in ferromo
lybdenum and ferroniobium using X-Ray fluorescence by wavelength dispe
rsion and energy dispersion. Ensuring a good sample preparation system
and the availability of an appropriate set of calibration samples is
the most important part of any instrumental analytical technique, havi
ng an important bearing on the accuracy of the analytical results. The
remelting technique is capable of dealing with the two major factors
that cause difficulties in the practical application of X-ray fluoresc
ence techniques to the analysis of ferroalloys: their unsuitability fo
r direct instrumental analysis and the availability of accurately anal
ysed standards in a suitable form and in sufficient quantities to adeq
uately cover the required composition ranges. The remelting technique
makes it possible to change the physical form of the ferroalloy sample
into one appropriate for X-ray measurements, while at the same time d
iluting with an appropriate quantity of pure iron (avoiding the proble
m of sample fracturing during cooling, chilling or polishing), and all
ows to prepare sets of calibration samples from appropriate proportion
s of the main element and pure iron. Test samples were prepared by rem
elting the ferroalloy diluted with iron using the following proportion
s: 15 g of FeMo + 25 g of Fe for ferromolybdenum analysis and 12 g of
FeNb + 28 g of Fe for ferroniobium analysis. Calibration samples were
obtained in two different ways: from a commercial ferroalloy diluted w
ith iron in different proportions and from adequate proportions of the
main constituent pure metal and iron. Precisions (relative standard d
eviations), influenced by the sample preparation system and by the ins
trumental variability, better than 0.6% were obtained for both type of
ferroalloys using both X-ray dispersive systems.