Spark Discharge Atomic Emission Spectrometry for Compositional Analysis of Band Electrode Surfacing Deposited Metal

Literature Overview

This study by Liu Manyu et al. (2018), published in Metallurgical Analysis (Vol. 38, No. 11), addresses a critical practical problem in the quality control of band electrode surfacing operations. The paper investigates the application of spark discharge atomic emission spectrometry (SD-AES) for the determination of seven elements—carbon, silicon, manganese, sulfur, phosphorus, chromium, and nickel—in deposited metal produced by band electrode surfacing processes. The work was conducted by Harbin Weier Welding Co., Ltd. and Hawan Institute Huatong (Changzhou) Welding Industry Co., Ltd., supported by the National Key R&D Program of China (2017YFB0305303) and the Heilongjiang Provincial Research Institution Innovation Capability Enhancement Program (YC2015D009).

Core Technical Problem and Motivation

In industrial surfacing production, the chemical composition of deposited metal directly governs the performance characteristics of the final coating—whether wear resistance, corrosion resistance, or metallurgical compatibility with the substrate. SD-AES is the industry-standard rapid analytical method for routine inspection because of its speed, multi-element capability, and minimal sample preparation requirements. However, the authors identified a fundamental challenge: the microstructure, grain orientation, and surface morphology of band electrode surfacing deposits differ significantly from those of conventional wrought or cast steel reference standards. When commercial stainless steel reference standards (such as ZBGS003) are used as type-standardization samples, the analysis results exhibit systematic deviations, particularly for chromium, manganese, and carbon. This discrepancy arises because the matrix effect in SD-AES is highly sensitive to the physical state of the sample—its grain structure, surface roughness, and elemental segregation patterns.

Optimization of Light Source Parameters

The authors systematically optimized three key light source parameters to establish a reliable analytical protocol:

This parameter set represents a careful balance between signal-to-noise ratio, analysis speed, and sample consumption. In practice, for surfacing deposits—which often have a rougher, more heterogeneous surface than machined test bars—the flush time is particularly critical. Insufficient flushing leads to surface oxide interference, while excessive flushing can alter the surface composition through preferential evaporation of low-melting-point elements such as carbon and sulfur.

Type Standardization Methodology Comparison

The central finding of this paper is the comparison between two standardization approaches:

The use of self-made control samples—prepared from actual production surfacing deposits with certified chemical compositions determined by wet chemical analysis—provides a matrix-matched standardization that eliminates the matrix effect inherent in using dissimilar reference materials. This approach requires significant initial investment in sample preparation and certification but yields dramatically improved analytical accuracy for routine production monitoring.

Engineering Practice Implications

From a quality control standpoint, this study has direct implications for any facility performing band electrode surfacing for applications such as:

• Pipeline repair and internal coating systems
• Wear-resistant overlays on rotating equipment
• Corrosion-resistant linings in chemical processing equipment

The key insight is that analytical methods must be matrix-matched to the material being analyzed. This principle extends beyond SD-AES to other spectroscopic techniques such as optical emission spectrometry (OES) used in production-line quality monitoring. The recommendation is clear: invest in developing in-house control sample libraries for each distinct surfacing process and filler metal type used in production.

Key Questions and Reflections

Several questions merit further consideration. First, the paper does not address the long-term stability of self-made control samples—how do they degrade with repeated use, and at what point should they be replaced? Second, the study focuses on seven elements, but modern surfacing alloys often contain additional alloying elements such as molybdenum, tungsten, cobalt, and rare earths. The matrix-matching principle should be validated for these elements as well. Third, the paper does not discuss the spatial heterogeneity of surfacing deposits—a single deposit may have compositionally distinct zones depending on the number of passes, overlap patterns, and cooling rates between passes. The sampling location and preparation method for SD-AES analysis of multi-pass surfacing deposits deserve further standardization.

Study Insights and Implications

This study exemplifies the principle that analytical accuracy in welding quality control depends not only on instrument calibration but fundamentally on the appropriateness of the reference standard matrix. For engineers managing surfacing production lines, the practical takeaway is to establish a systematic program for developing and maintaining matrix-matched control samples. The optimized light source parameters provide a reproducible analytical protocol that can be implemented across different SD-AES instruments. The work also highlights the importance of inter-laboratory comparison between spectroscopic and wet chemical methods to validate analytical procedures periodically. In the context of pipeline integrity management and equipment life extension, where surfacing deposits must meet exacting compositional specifications, this matrix-matching approach is not merely an analytical refinement but a fundamental requirement for reliable quality assurance.