在拉力负荷下预测自然存在的表面涂料的断裂趋势
Jeremy A Scher1, Brandon Foley1, Maxwell Murialdo1
1Lawrence Livermore National Laboratory, Livermore, California 94550 United States.
ACS applied materials & interfaces
|May 4, 2024
概括
分子动力学模拟显示,氧化涂层比氧化涂层更容易发生机械故障. 像谷物边界和孔隙等缺陷显著削弱氧化,影响耐腐蚀性和部件寿命预测.
科学领域:
- 材料科学 材料科学 材料科学
- 计算材料科学科学 计算材料科学
- 腐蚀科学 腐蚀科学
背景情况:
- 自然存在的氧化和氧化涂层保护免受腐蚀.
- 了解这些涂料的机械故障对于预测元件寿命至关重要.
- 预测模型需要详细了解不同条件下的涂层特性.
研究的目的:
- 开发和应用分子动力学 (MD) 建模框架,用于氧化和氧化涂层的张力测试.
- 调查涂层化学,缺陷形态和加载路径对机械强度的影响.
- 提供有关表面涂料机械故障机制的见解.
主要方法:
- 利用分子动力学 (MD) 模拟,对γ-Al2O3 (氧化物) 和γ-Al(OH) 3 (氧化物) 模型进行拉力测试.
- 模拟了缺陷的影响,例如颗粒边界和孔隙性对涂层强度的影响.
- 分析了诸如故障时应变和在单轴拉伸负荷下屈服应力等参数.
主要成果:
- 与氧化 (0.31 和 11.1 GPa) 相比,氧化在故障 (0.08) 和屈服应力 (1.6 GPa) 时表现出明显较低的应变.
- 氧化的缺陷大大降低了其机械强度:颗粒边界在故障时降低了应变,孔隙性降低了产量应力 (例如,20%的孔隙性减少了53%的产量应力).
- 炎热和潮湿的条件有利于氧化物和缺陷氧化物形成,这表明复杂的老化对腐蚀和应力腐蚀裂纹的影响.
结论:
- 氧化涂层在机械上比氧化涂层强度要低得多.
- 涂层缺陷极大地影响氧化的机械完整性和故障模式.
- 这些发现表明,环境老化历史显著影响了对腐蚀和应力腐蚀裂纹的易受性,这是由于涂层性能的变化造成的.
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