Non-Contact LIBS Analysis for Liquid Metal Impurity Control
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Solution Overview
Problem
Existing LIBS techniques for quantitative analysis of liquid metals suffer from limited accuracy and precision, requiring immersion probes that need frequent cleaning and replacement, and are inferior to methods like Spark OES and ICP-AES/MS, especially for elemental analysis in metal production processes.
Innovation Solution
A non-contact, non-immersive method and apparatus using LIBS technology with precise positioning of receiving optics and sample containers to maintain a predetermined distance from the sample surface, allowing for accurate quantitative analysis of liquid metals and alloys without immersion, achieving low detection limits and high repeatability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If immersive probes are used for LIBS analysis of liquid metals, then direct in-situ measurement is enabled, but measurement accuracy is insufficient and probes require frequent cleaning and replacement
Solution Approach 1:
The invention extracts the probe from the liquid metal environment by using a non-contact optical measurement approach. The LIBS system measures liquid metal composition through optical emission spectra without immersing any physical probe into the molten metal, thereby eliminating contamination and accuracy degradation issues while maintaining direct in-situ measurement capability
Solution Approach 2:
The invention replaces the mechanical immersive probe system with an optical field-based measurement system. Instead of using physical contact between a probe and liquid metal, the system uses laser-induced plasma emission and optical spectroscopy to achieve non-contact compositional analysis, thereby eliminating the limitations of immersive probes
2Productivity
If traditional LIBS is applied directly to liquid metal samples, then fast analysis is achieved, but quantitative accuracy is limited and inferior to Spark OES and ICP methods
Solution Approach 1:
The invention changes the measurement parameters by optimizing laser pulse energy, repetition rate, and timing delays to maximize plasma emission intensity and spectral resolution. By adjusting these parameters and using internal standards for normalization, the system achieves quantitative accuracy comparable to Spark OES and ICP methods while maintaining the fast analysis speed of direct LIBS
Solution Approach 2:
The invention introduces an internal standard element (such as an alloying element present in known concentration) as a mediator to normalize the LIBS signal. This internal standard compensates for variations in plasma conditions and matrix effects, enabling accurate quantitative analysis of trace elements in liquid metal without sacrificing analysis speed
3Measurement precision
If liquid metal samples are solidified and analysed, then accurate elemental composition is obtained, but time is lost due to cooling and solidification process
Solution Approach 1:
The invention performs preliminary action by maintaining the liquid metal sample in a controlled environment (such as a heated crucible or mold) that preserves its liquid state and prevents premature solidification. This allows direct LIBS measurement of the liquid metal composition without requiring subsequent cooling and solidification steps, thereby eliminating time loss while maintaining measurement accuracy
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method achieves low limit of detection (LOD) values as low as 1 ppm, high measurement repeatability, and precision, making it suitable for process and quality control in metallurgy industries, comparable to high-end OES systems.
Implementation Method 1
Laser-Induced Breakdown Spectroscopy, LIBS, is an atomic emission spectroscopy technique which uses high-energy laser pulses to excite a sample, creating a plasma composed of matter in a highly excited energy state and detecting light emitted from the plasma during its subsequent relaxation
Implementation Method 2
detecting light emitted from the plasma during its subsequent relaxation, which includes spectrally narrow emission characteristic of the elements in the sample
Data Source
AI summary
A non-contact, non-immersive method and apparatus are provided for accurately measuring quantitatively one or more elements in liquid metal or alloy samples using laser-induced breakdown spectroscopy (LIBS). The method is particularly useful for process and/or quality control within the metallurgy industry for accurately and very quickly measuring minor component or impurity elements in liquid metal in the production process, without touching the liquid metal and without the need for cooling and solidifying samples for analysis. In the method and apparatus a pre-determined distance is dynamically maintained between emission receiving optics and the surface of a liquid sample being analysed and the instrument does not come in contact with the liquid metal surface. Liquid samples are heated and/or maintained at a desired temperature. For many elements, values for limit-of-detection, measurement repeatability and accuracy about or below 1 ppm are achieved using this method.