Recent Improvements in the Analysis of Inclusions in Aluminum with the ARL 4460 Spark-DAT

In the past years inclusions analysis with Spark-DAT, an option of the Thermo Scientific ARL 4460 optical emission spectrometer, has become popular in the steel industry. Numerous companies now routinely use it, firstly because it has an extremely short analysis time that allows using it for controlling the steel elaboration process.

The recent improvements in the inclusion analysis with Spark-DAT will help making Spark-DAT a routine method for aluminum and its alloys as well.

The aluminum industry has also big challenges with inclusions that affect for example mechanical properties, gas porosity, machinability, surface quality and fluidity. Measuring them in the melt is therefore important for process monitoring and control in production. Spark-DAT analysis is cost and time-effective and has large potential to replace, facilitate or simplify the existing techniques of inclusions assessments in aluminum.

Benefits of using Spark-DAT

The most important benefits of using Spark-DAT are the following:

• Drastic reduction of investment costs for inclusion analysis, the OES instrument being sufficient to provide inclusions’ related information in addition to the analysis in concentration
• No additional costs and time for operations, maintenance, service and sample preparation for inclusion analysis, compared to the standard OES spectrometer
• Inclusion analysis can be performed in the same sequence with the analysis in concentration
• Unequalled perspectives for getting information on the inclusions during the production process, the inclusion information being available within a few minutes from sample taking
• Inclusion analysis is possible for up to about 30 samples per hour

Principles of inclusion analysis with Spark-DAT

In OES (optical emission spectroscopy), typically two thousands single sparks performed in a few seconds between an electrode and the metallic sample to analyze are used for generating emission signals of the elements to analyze. For quantitative analysis, the single components of the emitted light intensity of interest are integrated and the integrated intensity is transformed into a concentration through a calibration curve.

With Spark-DAT the single signal intensities are acquired separately and processed based on statistical principles with mathematical algorithms. These algorithms allow the evaluation of inclusions number and composition, and allow qualitative size analysis.

Improvement of Spark-DAT analysis of aluminum samples

The following table summarizes the improvements that were realized recently for Spark-DAT analysis in aluminum.

Instrumentation

For the ARL 4460 spectrometer used for inclusions analysis in aluminum matrix, we recommend VUV (vacuum ultra-violet) lines for elements like C, N, O and Cl in addition to the standard lines of an OES aluminum instrument, because they allow monitoring very important inclusions..

Conclusions

The ability to obtain elemental analysis and information on the inclusion contents with a single OES instrument greatly reduces investment cost. Moreover the sample and its surface preparation, as well as the instrument maintenance and consumables, are unchanged compared to a standard OES instrument, ensuring very low operating cost.

The Spark-DAT option on the Thermo Scientific ARL 4460 Metals Analyzer increases the versatility of the spectrometer. From routine use to research, Spark-DAT provides a quick, simple and cost-effective solution for inclusion analysis in the aluminum industry.

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