20025-01-31 バージニア工科大学 (Virginia Tech)
＜関連情報＞
- https://news.vt.edu/articles/2025/01/eng-coe-mse-solid-discovery.html
- https://www.nature.com/articles/s41467-024-54482-w
酸化スピネルが超合金の高温自己潤滑を可能にする Spinel oxide enables high-temperature self-lubrication in superalloys
Zhengyu Zhang,Eitan Hershkovitz,Qi An,Liping Liu,Xiaoqing Wang,Zhifei Deng,Garrett Baucom,Wenbo Wang,Jing Zhao,Ziming Xin,Lowell Moore,Yi Yao,Md Rezwan Ul Islam,Xin Chen,Bai Cui,Ling Li,Hongliang Xin,Lin Li,Honggyu Kim & Wenjun Cai
Nature Communications Published:20 November 2024
DOI:https://doi.org/10.1038/s41467-024-54482-w
Abstract
The ability to lubricate and resist wear at temperatures above 600 °C in an oxidative environment remains a significant challenge for metals due to their high-temperature softening, oxidation, and rapid degradation of traditional solid lubricants. Herein, we demonstrate that high-temperature lubricity can be achieved with coefficients of friction (COF) as low as 0.10-0.32 at 600-900 °C by tailoring surface oxidation in additively-manufactured Inconel superalloy. By integrating high-temperature tribological testing, advanced materials characterization, and computations, we show that the formation of spinel-based oxide layers on superalloy promotes sustained self-lubrication due to their lower shear strength and more negative formation and cohesive energy compared to other surface oxides. A reversible phase transformation between the cubic and tetragonal/monoclinic spinel was driven by stress and temperature during high temperature wear. To span Ni- and Cr-based ternary oxide compositional spaces for which little high-temperature COF data exist, we develop a computational design method to predict the lubricity of oxides, incorporating thermodynamics and density functional theory computations. Our finding demonstrates that spinel oxide can exhibit low COF values at temperatures much higher than conventional solid lubricants with 2D layered or Magnéli structures, suggesting a promising design strategy for self-lubricating high-temperature alloys.
