The effect of a pack cementation coating on the oxidation of a Mo-Nb-Si-B alloy

IF 5.3 2区材料科学 Q1 MATERIALS SCIENCE, COATINGS & FILMS

Surface & Coatings Technology Pub Date : 2025-06-17 DOI:10.1016/j.surfcoat.2025.132408

Liam F. Wood, John H. Perepezko

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Abstract

The commonly studied Mo-Si-B alloys are based upon a multiphase microstructure comprising the Mo_ss + Mo₅SiB₂ (T₂) + Mo₃Si (A15) phases. For structural applications, Mo-Si-B alloys must include the Mo_ss phase to have adequate ductility and fracture toughness, but the T₂ phase provides the majority of oxidation and creep resistance. The Mo₅Si₃ (T₁) phase, having a high Si content and saturated in B, also offers good oxidation resistance but is not in equilibrium with the Mo_ss and T₂ phases. Adding Nb destabilizes the A15 phase, enabling a eutectic reaction in a Mo-32.6Nb-19.5Si-4.7B alloy that yields the Mo_ss + T₁ + T₂ phases, and is thermally stable to 1925 °C. The oxidation behavior of the three-phase alloy was conducted by thermogravimetric analysis (TGA) at temperatures between 700 °C-1300 °C and showed a 28 mg/cm² mass loss after 50 h at 1100 °C. The oxidation behavior was modeled using the individual phase reactions to provide a good account of the TGA results. To address the significant alloy oxidation, a SiB pack cementation coating that develops a multilayer structure with an outer borosilica layer was applied to the Mo-Nb-Si-B alloy. The coated as-cast alloy exhibited a mass gain of 1 mg/cm² after 50 h at 1100 °C, and cyclic oxidation testing of the coated heat-treated alloy showed a mass loss of only 1.74 mg/cm² after 23 cycles at 1300 °C, demonstrating robust oxidation resistance.

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包覆层对Mo-Nb-Si-B合金氧化的影响

通常研究的Mo-Si-B合金是基于由Moss + Mo5SiB2 (T2) + Mo3Si （A15）相组成的多相组织。对于结构应用，Mo-Si-B合金必须包含Moss相以具有足够的延展性和断裂韧性，但T2相提供了大部分的抗氧化和抗蠕变性能。Mo5Si3 （T1）相具有较高的Si含量和饱和的B，也具有良好的抗氧化性，但与Moss和T2相不平衡。添加Nb使A15相不稳定，使Mo-32.6Nb-19.5Si-4.7B合金发生共晶反应，生成Moss + T1 + T2相，并且在1925℃前热稳定。通过热重分析（TGA）对三相合金在700°C-1300°C的氧化行为进行了分析，结果表明，在1100°C下加热50 h后，合金的质量损失为28 mg/cm2。氧化行为是用单个相反应来模拟的，以提供TGA结果的一个很好的帐户。为了解决明显的合金氧化问题，在Mo-Nb-Si-B合金上应用了一种SiB包覆胶结涂层，该涂层具有外层硼硅层，可形成多层结构。涂层合金在1100℃下加热50 h后，质量增加1 mg/cm2，在1300℃下循环氧化测试，涂层热处理合金在1300℃下循环23次后，质量损失仅为1.74 mg/cm2，具有良好的抗氧化性。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Surface & Coatings Technology 工程技术-材料科学：膜

CiteScore

10.00

自引率

11.10%

发文量

921

审稿时长

19 days

期刊介绍： Surface and Coatings Technology is an international archival journal publishing scientific papers on significant developments in surface and interface engineering to modify and improve the surface properties of materials for protection in demanding contact conditions or aggressive environments, or for enhanced functional performance. Contributions range from original scientific articles concerned with fundamental and applied aspects of research or direct applications of metallic, inorganic, organic and composite coatings, to invited reviews of current technology in specific areas. Papers submitted to this journal are expected to be in line with the following aspects in processes, and properties/performance: A. Processes: Physical and chemical vapour deposition techniques, thermal and plasma spraying, surface modification by directed energy techniques such as ion, electron and laser beams, thermo-chemical treatment, wet chemical and electrochemical processes such as plating, sol-gel coating, anodization, plasma electrolytic oxidation, etc., but excluding painting. B. Properties/performance: friction performance, wear resistance (e.g., abrasion, erosion, fretting, etc), corrosion and oxidation resistance, thermal protection, diffusion resistance, hydrophilicity/hydrophobicity, and properties relevant to smart materials behaviour and enhanced multifunctional performance for environmental, energy and medical applications, but excluding device aspects.