Rare Earth Elements Aren’t So Rare After All
The term ‘rare earth elements’ (REEs) is a misnomer and better refers to the relatively rare ores REEs are extracted from; rare earth elements are all around us!
The Battle Against Contamination: Challenges in
Superalloy Manufacturing
Superalloys are the unsung heroes of high-performance
industries: jet engines, gas turbines, and even nuclear reactors. However, for all their strength and thermal resistance, they are incredible sensitive to one critical factor: contamination. The most minute levels of contamination during manufacturing can have costly, and even catastrophic consequences.
Superalloys, mainly those based on nickel, cobalt, or iron, operate in extreme environments. High temperatures, oxidative atmospheres, and prolonged stress exposure are norms. In these conditions, impurities like sulfur, phosphorus, or oxygen (even n parts per million) for instance, can lead to grain boundary embrittlement, creep failure, or loss of corrosion resistance.
Combating Superalloy Contamination Challenges
Despite advances in metallurgy, contamination risks can happen throughout the production process:
- Raw Materials: If the feedstock metal isn’t of certified purity, you’re already starting off with a disadvantage. Recycled materials can introduce unknown residuals.
- Melting and Castine: Furnace linings and crucibles can leach trace elements into molten alloys. Atmospheric exposure during melting, especially outside a vacuum, introduces oxygen and nitrogen.
- Tooling and Molds: Sand cores or ceramic molds may contain trace elements that react with the molten alloy.
- Human Error: Cross-contamination from improperly cleaned equipment or mixing up alloy batches.
To combat these challenges, EAG Laboratories’ expert scientists employ a multi-layered approach to measure and evaluate superalloys:
- Rigorous and Thorough Quality Testing: Techniques like GDMS (Glow Discharge Mass Spectrometry) and ICP-MS (Inductively Coupled Plasma Mass Spectrometry) are used to detect and quantify even trace levels of elements, ensuring that the material meets the high standards required for critical applications. These techniques are beneficial for identifying impurities or variations in alloy compositions, which could affect the final product’s performance, durability, and reliability.
- Depth Profiling Protocols: The accuracy of elemental profiling of conversion coated superalloy components provided by modulated fast-flow GDMS is superior for its sensitivity, multi-element capability, data spacing and depth resolution, and simple sample preparation requirements.
- Full Survey Elemental Coverage: EAG employes analytical techniques to cover the full survey of elements, including all gas forming elements, essential for ensuring that all critical components manufactured from superalloys are accurately evaluated.
Purity in superalloys is a performance and safety imperative. At EAG Laboratories, we take pride in the handling and characterizing materials. As demands for materials grow, our scientists will continue tightening controls, refining detection methods, and anticipating where the next impurity might try to sneak in.
Works Cited:
- Sims, C.T., Stoloff, N.S., and Hagel, W.C. (1987). Superalloys II. Wiley
- Reed, R.C. (2006). The Superalloys: Fundamentals and Applications. Cambridge University Press.
- Donachie, M.J., and Donachie, S.J. (2002) Superalloys: A Technical Gude. ASM International.
- ASTM International. (2023). ASTM E1473-20: Guide for Testing and Cleaning Refractories for Metal-Melting Furnaces.
- Zhang, Y., et al. (2018). “Contamination Control in Superalloy Investment Casting,” Materials and Science Forum, 941, 76-81.
- S. Department of Energy (DOE). (2011). Advanced Melting Technologies: Energy Saving Concepts and Opportunities.
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