XRF 1028
Beryllium Analysis
in Beryllium Copper Alloy
Wavelength dispersive
X-ray fluorescence
spectrometer
ZSX PrimusII
beryllium copper alloy
beryllium
copper alloy
http://en.wikipedia.org/wiki/File:CuBe_Tool.jpg
Introduction
Instrument
Beryllium copper alloy has almost as high strength as
steel, and is the strongest among copper alloys. In
addition, it has various features such as non-magnetic
and non-sparking characteristics, having high electrical
conductivity and ductility. Owing to these features,
beryllium copper has many uses; springs, electric
connectors, tools in environments with explosive vapors and gases, and musical instruments. Since characteristics and uses of beryllium copper alloys depend
on beryllium concentration, it is important to analyze
beryllium in beryllium copper.
Beryllium is the lightest element among the elements
which can be analyzed by XRF spectrometry. The element line of beryllium, Be-Kα has very long wavelength, 11.4 nm (or very low energy, 0.109 keV), having
very shallow critical depth. Therefore, X-ray intensities
of Be-Kα are significantly affected by the surface condition of specimens. For beryllium analysis by XRF
spectrometry, surface treatment is essential.
Owing to the long wavelength of Be-Kα, beryllium
analysis requires high-power wavelength-dispersive
X-ray fluorescence (WDXRF) spectrometers equipped
with the analyzing crystal with high reflectivity for
Be-Kα.
This application note demonstrates beryllium analysis
in beryllium copper alloy.
The ZSX PrimusII, a tube-above sequential wavelength dispersive X-ray fluorescence (WDXRF) spectrometer, is equipped with a 4 kW X-ray tube with a Rh
target, featuring a ultra-thin beryllium window, and four
analyzing crystals covering F to U. In this analysis, the
multi-layer analyzer, RX75 (optional) is also mounted
in the spectrometer.
For beryllium analysis, the APC (Auto Pressure Control) is effective, which is a function that keeps the
vacuum levels in the sample and optical chambers
constant during measurement. Without this function,
X-ray intensities of Be-Kα fluctuate by the change of
the vacuum levels in the X-ray path owing to the long
wavelength of Be-Kα.
The system software is designed for ease of use in
routine analyses. The Flowbar in quantitative analysis
guides users in establishing calibration. The Sample ID
Table and the Program Operation help operators carry
out daily analysis.
Measurements were performed on the ZSX PrimusII
with a 4 kW X-ray tube operating at 30 kV and 100 mA
using the RX75 multilayer analyzer and the S8
high-sensitivity slit (optional). The counting time was
300 seconds only for peak.
1
XRF 1028
Standard and sample preparation
Certified reference materials of beryllium copper alloy
provided by CTIF (France) were used for calibration.
Each sample was polished using a belt surfacer with a
#240 alumina abrasive belt.
Analysis result
Figure 1 shows the calibration curve obtained with
CTIF CRMs and a pure copper metal.
The accuracy of calibration is 0.12 mass% and the
lower limit of detection (LLD) is 0.09 mass%.
Figure 1 Beryllium calibration curve
The accuracy of calibration is calculated by the following formula,
Accuracy =
(
∑ Ci − Ĉi
i
)
Table 1 Repeatability test results
2
Run No.
Beryllium
conc. (mass%)
1
2
3
4
5
6
7
8
9
10
1.98
2.00
1.91
2.01
1.97
1.95
2.02
2.03
1.91
2.04
Average
Standard deviation
RSD
1.98
0.047
2.4%
n−2
Ci : calculated value of standard sample
Ĉ i : certified value of standard sample
n : number of standard samples
The LLD is calculated by the following formula,
IB
LLD = 3 ⋅ 1 ⋅ σ B = 3 ⋅
m
m 1000 × t
m : sensitivity of calibration (kcps/mass%)
σB : standard deviation of blank intensity (kcps)
IB : blank intensity (kcps)
t : counting time (s)
Conclusion
Repeatability tests were carried out using one of the
CRMs used for the calibration. The specimen was
polished and then measured, quantified with the calibration. This process was repeated ten times.
The test results are shown in Table 1.
Beryllium in beryllium copper alloy can be routinely
analyzed on the ZSX PrimusII with a 4 kW X-ray tube
with a Rh target, featuring a ultra-thin beryllium window,
and the multilayer analyzer RX75. It is necessary to
polish the surface of specimens prior to measurement.
The measurement of this application can be performed
also on the ZSX Primus, a tube-below sequential
wavelength dispersive X-ray fluorescence (WDXRF)
spectrometer.
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