Design and Performance
of a CCD array spectrometer with an argon
flushed spark source for metals analysis
Dr Trevor Smith
Arun Technology Ltd. UK
Presentation for Pittcon ‘96
Content
Photographic Plate Based Systems
Photomultiplier Tube Based Spectrometer
Photomultiplier Based Spectrometer
The CCD Spectrometer
CCD Spectrometer Geometry
Specification of CCD Spectrometer
|
Dynamic Range |
15000:1 |
|
Pixel Bandwidth |
0.1nm |
|
Spectral Resolution |
0.3nm |
|
Wavelength Coverage |
185 - 410 nm |
|
Channels |
>700 |
Advantages of CCD Spectrometer compared with PMT Based Spectrometers
Spectrum of Pure Aluminium
Spectrum of Pure Aluminium
showing background noise
Ni in Cast Iron - Multiple Lines
Line Position Tracking - Automatic Profiling
Spark PSU Specification
|
Spark Frequency |
100-600 Hz |
|
Flush Time |
0 - 20 sec |
|
Preburn Time |
0 - 120 sec |
|
Preburn Current |
up to 160A peak |
|
Burn Time |
0.5 - 60 sec |
|
Burn Current |
20 - 120 A peak |
Source Specification
|
Electrode Gap |
4mm (3-6mm) |
|
Electrode |
2% Th in W 4mm dia |
|
Sample Plate Aperture |
13mm |
|
Standby Argon Rate |
0.5 l/min |
|
Flush Rate |
5 l/min |
|
Viewing angle |
20° to Horizontal |
|
Cathode Masking |
Not used |
Near Line Ratioing - Cast Iron
|
Element |
Analyte |
Fe Ratio |
Element |
Analyte |
Fe Ratio |
|
C |
193.09 |
188.90 |
Ni |
345.85 |
344.08 |
|
Si |
288.16 |
273.96 |
Mo |
386.41 |
388.63 |
|
Cu |
327.40 |
328.68 |
Al |
396.15 |
396.92 |
|
Sn |
317.51 |
330.62 |
V |
311.07 |
310.04 |
|
Ti |
323.45 |
322.61 |
Mg |
280.27 |
275.56 |
|
Cr |
267.72 |
263.12 |
Pb |
405.78 |
404.59 |
|
Mn |
293.31 |
|
|
293.69 |
|
Multiple Line Averaging
Ni in Cast Iron
|
|
|
Relative Standard Deviation (%) |
||||||||||
|
Sample |
Conc (%) |
Ni 231.60 |
Ni 341.47 |
Ni 345.85 |
Ni 349.30 |
Ni Average |
||||||
|
SCRM666-8 |
1.88 |
1.91 |
1.02 |
1.59 |
1.75 |
1.11 |
||||||
|
SCRM667-8 |
1.31 |
1.32 |
1.27 |
0.44 |
1.68 |
0.78 |
||||||
|
SCRM668-8 |
0.19 |
5.80 |
5.85 |
5.03 |
8.32 |
4.96 |
||||||
|
SCRM669-8 |
0.51 |
1.02 |
2.92 |
6.74 |
2.45 |
2.04 |
||||||
|
SCRM670-8 |
0.86 |
0.29 |
2.27 |
1.00 |
2.42 |
1.17 |
||||||
For each sample, n = 4
Long Term Stability and Repeatability
|
Matrix |
N |
Typical RSD for Major Elements |
Typical RSD for Minor Elements |
|
Aluminium Alloy |
12 |
2.5 |
15.0 |
|
Brass |
10 |
2.5 |
7.0 |
|
Tin Bronze |
10 |
2.0 |
13.0 |
|
Aluminium Bronze |
10 |
1.0 |
7.5 |
|
Manganese Brass |
10 |
1.8 |
8.0 |
|
Cupro-Nickels and Nickel Silvers |
10 |
1.5 |
8.5 |
|
Silicon Bronze |
4 |
2.6 |
4.5 |
|
Cast Iron |
5 |
2.2 |
11.5 |
|
Zinc Alloy |
4 |
2.5 |
10.0 |
Division of Major and Minor Elements
Threshold Levels for Aluminium
|
Element |
Minor |
Major |
|
Si |
0.01 - 0.3 |
0.3 - 15.0 |
|
Fe |
0.01 - 0.2 |
0.2 - 2.5 |
|
Cu |
0.01 - 0.4 |
0.4 - 12.0 |
|
Mn |
0.05 - 0.1 |
0.1 - 1.5 |
|
Mg |
0.005 - 0.05 |
0.05 - 12.0 |
|
Cr |
0.03 - 0.1 |
0.1 - 0.5 |
|
Ni |
0.05 - 0.5 |
0.5 - 4.0 |
|
Zn |
0.005 - 0.5 |
0.5 - 10.0 |
|
Sn |
0.1 - 1.0 |
1.0 - 0.15 |
|
Ti |
0.01 - 0.05 |
0.05 - 0.2 |
|
Pb |
0.03 - 0.3 |
0.3 - 0.6 |
|
Be |
0.0001 - 0.015 |
|
|
Bi |
0.05 - 0.7 |
|
|
Ca |
0.001 - 0.03 |
|
|
Cd |
0.003 - 0.3 |
|
|
Sr |
0.0006 - 0.05 |
|
|
V |
0.01 - 0.15 |
|
|
Zr |
0.005 - 0.3 |
|
Further Matrices Planned
|
|
Available |
|
Low Alloy Steel and Carbon Steel |
Now |
|
Stainless Steel |
Now |
|
Tool Steel |
Now |
|
Inconel/Hastelloy |
Now |
|
Incoloy |
Now |
|
Monel |
Now |
|
Nickel Cobalts |
Now |
|
Zinc Alloys |
April 96 |
|
Magnesium Alloys |
April 96 |
|
Pure Zinc |
April 96 |
|
Pure Copper |
May 96 |
|
Beryllium Copper |
June 96 |
Example Application - Aluminium Casting Plant
Using External Test House
|
Materials |
LM24 and LM6 (380 and 413) |
|
Pots |
10 |
|
Tests Per Day |
20 |
|
Cost per Month |
$3000 |
|
Cost per Year |
$36000 |
Example Application
Aluminium Casting Plant
Using Metalscan 2000
|
Capital Cost over 3 years (per year) |
$12,000 |
|
Argon and other Consumables (per year) |
$3,000 |
|
Total Costs |
$15000 |
Analytical Ranges for the Aluminium Casting Application
|
|
380 |
413 |
Metalscan 2000 |
|
Si |
7.5 - 9.5 |
11.0 - 13.0 |
0.01 - 15.0 |
|
Fe |
0.1 - 1.3 |
0.05 - 0.6 |
0.006 - 1.5 |
|
Cu |
3.0 - 4.0 |
0.01 - 0.1 |
0.003 - 12.0 |
|
Mn |
0.05 - 0.5 |
0.05 - 0.5 |
0.001 - 1.5 |
|
Mg |
0.01 - 0.1 |
0.01 - 0.05 |
0.01 - 12.0 |
|
Cr |
|
|
0.01 - 0.5 |
|
Ni |
0.05 - 0.5 |
0.01 - 0.05 |
0.01 - 4.0 |
|
Zn |
0.05 - 0.9 |
0.01 - 0.1 |
0.005 - 10.0 |
|
Sn |
0.05 - 0.35 |
|
0.05 - 0.5 |
|
Ti |
|
0.01 - 0.25 |
0.001 - 0.2 |
|
Pb |
|
|
0.02 - 0.6 |
|
Be |
|
|
0.0001 - 0.015 |
|
Bi |
|
|
0.05 - 0.7 |
|
Ca |
|
|
0.001 - 0.03 |
|
Cd |
|
|
0.001 - 0.3 |
|
Sr |
|
|
0.0005 - 0.05 |
|
V |
|
|
0.003 - 0.15 |
|
Zr |
|
|
0.01 - 0.3 |
Aluminium Casting - Further Advantages
Conclusions