Analyzing Aluminum Alloys with ARL easySpark Optical Emission Spectrometer

For over 80 years, Thermo Fisher Scientific has established the standard of quality for optical emission spectrometer employed for metal analysis. Performance, reliability and stability have been the main attributes of the instruments, normally designed for labs and metals producers. The Thermo Scientific™ ARL easySpark™ metals analyzer continues this tradition of technical innovation and experience in order to provide the best value based solution for customers.

ARL easySpark

The ARL easySpark is capable of determining all the elements needed in the current and future applications, in almost all aluminum alloys. It is the answer to the analytical requirements, whether for incoming goods control, process QC, final product QC, metal sorting, investigation or certification. The ARL easySpark metals analyzer delivers dependable performance year after year with maximum uptime. Specific performance is detailed in this article.

AI alloys

ARL easySpark – Revolution in Benchtop OES

The ARL easySpark is considered to be a compact bench-top spectrometer based on an innovative multi grating/CCD optical design operated under argon environment at controlled temperature. It offers optimal resolution and stability, complete elemental coverage and delivers great performance for all the important elements.

The ARL easySpark benefits also from the same improved features that are already being used in bigger floor standing instruments of the Thermo Scientific OES product line, among which:

  • Compact version of the intelliSource, a digital spark source with increased efficiency and flexibility
  • Enhanced CCD signal acquisition and processing for improved accuracy and performance
  • ECOmode and super ECOmode permitting significant argon savings when the instrument is idle
  • Optimal design increasing the instrument functionality
  • Spark stand with optimal operator safety and minimize argon consumption during the analysis

ARL easySpark – Typical Precision Values (1 sigma) for Aluminum Matrix

Elements Ag As B Be Bi Ca Cd Co Cr Cu Fe Ga Hg Li Mg
Level % Precision
0.0001
0.0002 0.000004 0.00004
0.0005 0.00001 0.00005 0.000017 0.00009
0.001 0.00006 0.00013 0.00001 0.00006 0.00010 0.00010 0.00014 0.00007 0.00013 0.00002 0.00015
0.002 0.00007 0.0011 0.00014 0.00002 0.0008 0.00007 0.00012 0.00011 0.00017 0.00010 0.00020 0.00026 0.00003 0.0002
0.005 0.00009 0.0014 0.00017 0.00005 0.0008 0.00010 0.00017 0.00014 0.00025 0.00019 0.00033 0.0003 0.00033 0.00005 0.0003
0.01 0.0001 0.0017 0.00019 0.0001 0.0010 0.00012 0.0002 0.0002 0.0003 0.0003 0.0005 0.00035 0.0004 0.0002 0.0004
0.02 0.0002 0.0020 0.00022 0.0002 0.0011 0.00014 0.0003 0.0002 0.0004 0.0005 0.0007 0.0004 0.0005 0.0003 0.0005
0.05 0.0025 0.0005 0.0018 0.0005 0.0004 0.0008 0.0009 0.0012 0.0008 0.0007 0.0008
0.1 0.0030 0.0007 0.0017 0.0017 0.0017 0.0014
0.2 0.0045 0.0013 0.0032 0.0028 0.0027 0.0030
0.3 0.0060 0.0018 0.0046 0.0038 0.0035 0.0038
0.5 0.0083 0.0027 0.0072 0.0056 0.0050 0.0055
1 0.0130 0.0098 0.0075 0.0090
2 0.016 0.012 0.015
3 0.023 0.020
4 0.028 0.024
5 0.033 0.029
10 0.056 0.047
20
30
40

Elements Mn Mo Na Ni P Pb Sb Sc Si Sn Sr Ti V Zn Zr
Level % Precision
0.0001
0.0002
0.0005 0.00008 0.00002
0.001 0.00010 0.00003 0.00003 0.0001 0.00007 0.0002
0.002 0.00012 0.0006 0.00005 0.00032 0.0002 0.00003 0.00006 0.00015 0.00014 0.0001 0.00024
0.005 0.00016 0.0007 0.00012 0.0003 0.00035 0.0015 0.0018 0.0003 0.00035 0.00011 0.00024 0.00023 0.0002 0.00034
0.01 0.0002 0.0008 0.0002 0.0004 0.00038 0.0017 0.0023 0.0001 0.0004 0.0004 0.0002 0.0004 0.0003 0.0003 0.0004
0.02 0.0003 0.0003 0.0005 0.0018 0.0027 0.0002 0.0006 0.0005 0.0003 0.0006 0.0005 0.0005 0.0005
0.05 0.0006 0.0008 0.0020 0.0035 0.0005 0.0012 0.0008 0.0006 0.0014 0.0008 0.0008 0.0010
0.1 0.0010 0.0012 0.0023 0.0050 0.0008 0.0018 0.0018 0.0009 0.0050 0.0010 0.0013 0.0020
0.2 0.0015 0.0017 0.0024 0.0073 0.0014 0.0030 0.0030 0.0015 0.0110 0.0020 0.0032
0.3 0.0020 0.0025 0.0042 0.0090 0.0020 0.0037 0.0041 0.0170 0.0026 0.0043
0.5 0.0026 0.0045 0.0050 0.012 0.0052 0.0060 0.0036
1 0.0040 0.0075 0.0066 0.0090 0.0068
2 0.0060 0.0130 0.018 0.015
3 0.026 0.022
4 0.033 0.028
5 0.040 0.034
10 0.072 0.064
20 0.130
30 0.19
40

  • Homogeneity of the elements relies on the metallurgical structure obtained via the sampling procedure and on the metallurgical history including mechanical deformation. These values apply when homogeneously distributed elements are available in samples prepared by recommended sample preparation methods. A measured precision higher than the guaranteed precision indicates, with a probability higher than 95%, that the element has an inhomogeneous distribution over the sample’s surface or is segregated.
  • The precision values (given in percent) are typical instrumental repeatability. The guaranteed precision values are twice higher.
  • The precision values are based on ten repeated measurements.

Innovative CCD Optical System

On the ARL easySpark, the new multi grating/CCD optics permits a continuous spectral coverage combining optimal performance for every single element as well as high flexibility for future applications or spectral investigations. It features an exclusive UV resistant CCD detector that has been developed particularly for arc/spark OES and whose temperature is controlled by means of Peltier cooling device in order to guarantee the best precision and stability.

IntelliSource Digital Spark Source

The compact version of the Thermo Scientific patented intelliSource is a double current controlled source (CCS), the most innovative excitation source for Spark OES. It permits discharge shapes to be customized for most efficient control of the sample surface preparation, light emission and material ablation in a wide range of metal matrices. Matrix-optimized pre-integration sparks majorly reduce the effects of matrix and metallurgical structure (in re-melting the sample surface before the integration spark), which enhances the accuracy of the analysis.

Discharge Interrupt by Short-Circuit (DISC) that improves the repeatability in trace analysis is one among other innovative features that contributes to the performance of the intelliSource.

CCD Signal Acquisition and Processing

Different methods and techniques are applied to enhance performance with the CCD of the ARL easySpark like automatic dynamic dark current subtraction to improve the signal to noise ratio. Spectrum alignment and digital resolution enhancement are also carried out automatically during every acquisition in order to improve precision, long-term stability and accuracy.

Sample Preparation

The sample is usually prepared by using a milling machine or a lathe. Grinding is not possible due to the risk of contamination.

Performance Guarantee

The company guarantees the precision, which expresses the closeness of the concentration values of the individual runs of an analysis. The lowest the precision value, the smallest the number of runs required for high confidence in the average result.

Accuracy and Factory Calibration

The accuracy is considered to be the most vital figure of merit of a spectrometer. It expresses the agreement between the reference value and the result. It depends on the quality of the reference materials used for calibration, on some instrumental attributes (example, the spark source condition, the optical resolution) and on the mathematical model used to calculate the calibration curves. The calibrations are carried out by using thoroughly tested and well accepted reference materials (RM’s) and certified reference materials (CRM’s). The calibration curves are established utilizing extremely sophisticated multi-variable regression (MVR) software tool that corrects for matrix effects, spectral interferences and ensures the highest possible accuracy.

Calibration Summary

The following calibrations are available:

  • Al-Si
  • Al-Zn
  • Al-Mg
  • Al-Cu
  • Al-Si-Cu
  • Low alloy Aluminum
  • Global (including all qualities)

The calibrations are delivered as turn-key, completely parameterized applications along with setting-up samples (SUS) in order to maintain the accuracy of the calibration.

The measurement uncertainty can be displayed for each sample based on the repeatability of the measurements and the calibration curves.

Stability

Stability of the instrument is of extreme importance when executing routine analysis. High stability decreases the frequency for maintenance and drift correction operations.

The examples provided below show the long-term stability of Si and Cu in an Al-Si-Cu sample recorded over a period of five days without any intermediate drift correction. No standardization was needed, since the measured concentrations remained within an interval of +/- 2 times the guaranteed precision value, which is exceptional.

Memory Effects

The memory effect is defined as the number of runs necessary to decrease the measured concentration to the expected one after examining high alloyed samples, such as stainless steels. The ARL easySpark measures accurately trace elements after five runs.

Conclusion

The ARL easySpark is a compact, desktop spectrometer ideal for metals analysis, based on the latest CCD technology, which offers flexibility for the analysis. It can be installed and even made to work the same day it is delivered. The ARL easySpark, as well as being simple to handle, provides quick, reliable and precise analysis.

Its accuracy, along with its exceptional reliability and stability, makes it possible to obtain results users can rely on 24 hours a day, 365 days a year without spending too much time in expensive and long lasting drift corrections.

In addition, the ARL easySpark has the following advantages:

  • Unique safe open stand
  • New icon based easyOXSAS software
  • Widest range of metals analysis
  • Enhanced service/technical support
  • Easy and simple to use and maintain by unskilled operator
  • Low consumption of drift correction samples and simple maintenance

All these features allow users to optimize their productivity and to attain the shortest payback times:

Investment costs are reduced by:

  • Continuous upgrade possibilities (hardware and software) and exceptional instrument lifetime
  • Instrument capability to cover future requirements

Production costs are reduced by:

  • Increased instrument availability thanks to its high stability and less frequently required drift corrections
  • More accurate and reproducible analyzes made available in a rapid manner

Operating and maintenance costs are reduced by:

  • Significant argon savings during analysis and in stand-by
  • Low consumption of drift correction samples and simple maintenance

Overall cost management is reduced by:

  • Extremely low running costs compared to other methods
  • Optimum utilization of materials

This information has been sourced, reviewed and adapted from materials provided by Thermo Fisher Scientific - Elemental Analyzers.

For more information on this source, please visit Thermo Fisher Scientific - Elemental Analyzers.

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