杨天南,牛合全,孔令艳.γ-TiAl基合金用Al2O3-SiC-AlPO4复合涂层抗高温氧化性能研究[J].表面技术,2024,53(10):167-172, 206.
YANG Tiannan,NIU Hequan,KONG Lingyan.Resistance to High Temperature Oxidation of Al2O3-SiC-AlPO4 Coatings on γ-TiAl Based Alloys[J].Surface Technology,2024,53(10):167-172, 206
γ-TiAl基合金用Al2O3-SiC-AlPO4复合涂层抗高温氧化性能研究
Resistance to High Temperature Oxidation of Al2O3-SiC-AlPO4 Coatings on γ-TiAl Based Alloys
投稿时间:2023-07-13  修订日期:2023-10-13
DOI:10.16490/j.cnki.issn.1001-3660.2024.10.013
中文关键词:  γ-TiAl基合金  抗高温氧化性能  磷酸盐涂层  氧化动力学  微观组织
英文关键词:γ-TiAl alloy  resistance to high temperature oxidation  phosphate coatings  oxidation kinetics  microstructure
基金项目:
作者单位
杨天南 海装沈阳局驻沈阳地区某军事代表室,沈阳 110043 
牛合全 太原科技大学,太原 030024;中国科学院金属研究所,沈阳 110016 
孔令艳 中国科学院金属研究所,沈阳 110016 
AuthorInstitution
YANG Tiannan Military Representative Office of Shenyang Bureau of Navy Equipment Department, Shenyang 110043, China 
NIU Hequan Taiyuan University of Science and Technology, Taiyuan 030024, China;Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China 
KONG Lingyan Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China 
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中文摘要:
      目的 通过表面涂层提高γ-TiAl基合金的抗高温氧化性能。方法 采用常规喷涂涂料法在γ-TiAl合金基体上制备Al2O3-SiC-AlPO4磷酸盐复合抗高温氧化涂层。研究γ-TiAl合金和涂层样品在900 ℃、静态空气条件下的准等温氧化动力学行为。用XRD和SEM/EDS分别对涂层样品氧化前后的物相组成、组织形貌和微区成分进行表征分析;用电子探针(EPMA)分析涂层样品的元素分布情况。结果 900 ℃恒温氧化动力学研究结果表明,γ-TiAl基合金初期氧化速率常数为32.501×10−2 mg/(cm2.h1/2),与后期氧化速率常数28.113× 10−2 mg/(cm2.h1/2)基本接近,呈直线规律,不具有抗氧化性能;而Al2O3-SiC-AlPO4磷酸盐复合涂层样品氧化后期氧化速率常数为5.967×10−2 mg/(cm2.h1/2),与氧化初期8 h内氧化速率常数23.941×10−2 mg/(cm2.h1/2)相比,明显降低,遵循典型抛物线规律,具有抗氧化性能。微观分析结果表明,原始涂层与γ-TiAl合金基体结合紧密,涂层主要相组成为Al2O3、SiC、SiO2;AlPO4以无定形状态构成涂层连续相。氧化后,AlPO4演变成晶态,形成涂层致密的网络结构;部分基体钛元素扩散进入涂层中疏松部位,氧化后形成TiO2弥散分布在涂层中,填补了涂层疏松部位,使涂层更加致密;在涂层与基体界面2 μm区域内形成连续致密Al2O3膜,阻挡了空气中的氧进一步扩散进入基体。结论 Al2O3-SiC-AlPO4复合涂层有效降低了γ-TiAl基合金氧化速率,有助于形成保护性Al2O3膜,明显改善了900 ℃ γ-TiAl基合金抗高温氧化性能。
英文摘要:
      γ-TiAl based alloys are considered as promising high temperature light-weight structural materials due to their high specific strengths and elastic moduli. However, through analyzing the phase diagram of the Ti-Al-O system, it can be seen that the γ-TiAl based alloys can not form protective α-Al2O3 scale because of inadequate aluminum content in the alloy. Therefore, high temperature oxidation resistance coatings are still necessary to improve the anti-oxidation properties of γ-TiAl alloys at temperature above 800 ℃. Traditional coatings for high temperature oxidation, such as MCrAlY, suffer from severe inter-diffusion between coatings and the substrate, which will cause negative effect on alloy mechanical properties. Other types of coatings developed wildly, such as CrAlN ceramics, halogenation Si. Phosphate coatings are also ideal oxidation resistance coatings for their high temperature stability up to 1 400 ℃. In this work, Al2O3-SiC-AlPO4 composite phosphate coatings were designed and coated on γ-TiAl alloy substrate by conventional paint spraying method. The kinetic behavior of quasi-isotherm oxidation of γ-TiAl alloy and coating samples were studied at 900 ℃ under static air conditions. The physical phase composition, surface morphology and micro-zone composition of the coating samples before and after oxidation were characterized and analyzed by XRD and SEM/EDS, respectively. The element distribution of the coating samples were analyzed by electron probe (EPMA). The results of 900 ℃ anti-temperature oxidation experiments showed that the oxidation rate constant of γ-TiAl based alloy was 32.501×10−2 mg/(cm2.h1/2) at early oxidation stage, which was close to the oxidation rate constant of 28.113×10−2 mg/(cm2.h1/2)at late oxidation stage. This result indicated that the oxidation kinetics of the γ-TiAl based alloy followed straight line law, and the oxide scales of the bare alloy were not protective. The oxidation rate constant of Al2O3-SiC-AlPO4 composite coatings was 5.967×10−2 mg/(cm2.h1/2) at late oxidation stage, which was significantly lower than the initial oxidation rate constant 23.941×10−2 mg/(cm2.h1/2). The oxidation kinetics line of the coatings followed typical parabolic law, which indicated that protective oxide scales were formed on the coatings. Micro-structure analysis results showed that the composite coating and the γ-TiAl based alloys were combined well. The main phase of the coatings consisted of Al2O3, SiC and SiO2. AlPO4 existed in the coating in an amorphous state. After oxidation, AlPO4 crystallized and formed the main matrix of the coatings, forming a dense network structure of the coatings. Titanium elements of the γ-TiAl based alloy diffused into the network in the coatings and oxidized to TiO2 filling the holes, which led to a more dense coating. A continuous aluminum-rich inter-facial layer of about 2 μm between the coatings and the substrate was observed, which was the formation of a continuous and dense Al2O3 scale, preventing the oxygen from the air diffusing into the substrate. The Al2O3-SiC-AlPO4 composite coatings effectively prevent the diffusion of oxygen into the interior of the γ-TiAl alloy matrix at the temperature of 900 ℃, and show excellent anti-temperature oxidation properties. Due to the existence of the coatings, a 2 μm Al2O3 inter-layer is formed between the coating and the alloy after oxidation. This layer is condense without cracks, which may be the reason for the good adhesion and oxidation resistance property of the coating.
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