{"title":"alf3活化包埋法制备K447A镍基高温合金渗铝涂层的组织与氧化行为","authors":"Yuhang Zhao , Kai Zhou , Xin Xin , Xijun Zeng , Xiping Guo , Yanqiang Qiao","doi":"10.1016/j.surfcoat.2025.132236","DOIUrl":null,"url":null,"abstract":"<div><div>The function of AlF<sub>3</sub> activator, the aluminized coating formation mechanism on K447A nickel-based superalloy during the pack cementation process, and their oxidation behaviors have been systematically investigated. Comprehensive characterization by XRD, SEM, TEM and EDS analyses with HSC thermochemical calculation reveals four key findings: AlF<sub>3</sub> demonstrates the optimal aluminizing capability and generates active Al atoms via the disproportionation reaction of AlF gas. The aluminized coating exhibits a multilayer structure, with the outer layer composed of high Al content Ni<sub>2</sub>Al<sub>3</sub> or NiAl<sub>3</sub> and the inner layer consisting of NiAl. Precipitated phases such as α-(Cr, W), σ phase, and carbides are distributed in the aluminides, confirming an Al-dominated inward diffusion mechanism characteristic of a “high-activity” process. The coating thickness exhibits linear relationships to the reciprocal of temperature and holding time. Ni₂Al₃ is formed before NiAl, transforms into NiAl, and then is regenerated. After oxidizing at 1150 °C for 100 h, a protective ridged α-Al<sub>2</sub>O<sub>3</sub> scale forms on the aluminide coating, effectively shielding the substrate.</div></div>","PeriodicalId":22009,"journal":{"name":"Surface & Coatings Technology","volume":"510 ","pages":"Article 132236"},"PeriodicalIF":5.3000,"publicationDate":"2025-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Microstructure and oxidation behavior of the aluminized coating on K447A nickel-based superalloy prepared by AlF3-activated pack cementation\",\"authors\":\"Yuhang Zhao , Kai Zhou , Xin Xin , Xijun Zeng , Xiping Guo , Yanqiang Qiao\",\"doi\":\"10.1016/j.surfcoat.2025.132236\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><div>The function of AlF<sub>3</sub> activator, the aluminized coating formation mechanism on K447A nickel-based superalloy during the pack cementation process, and their oxidation behaviors have been systematically investigated. Comprehensive characterization by XRD, SEM, TEM and EDS analyses with HSC thermochemical calculation reveals four key findings: AlF<sub>3</sub> demonstrates the optimal aluminizing capability and generates active Al atoms via the disproportionation reaction of AlF gas. The aluminized coating exhibits a multilayer structure, with the outer layer composed of high Al content Ni<sub>2</sub>Al<sub>3</sub> or NiAl<sub>3</sub> and the inner layer consisting of NiAl. Precipitated phases such as α-(Cr, W), σ phase, and carbides are distributed in the aluminides, confirming an Al-dominated inward diffusion mechanism characteristic of a “high-activity” process. The coating thickness exhibits linear relationships to the reciprocal of temperature and holding time. Ni₂Al₃ is formed before NiAl, transforms into NiAl, and then is regenerated. After oxidizing at 1150 °C for 100 h, a protective ridged α-Al<sub>2</sub>O<sub>3</sub> scale forms on the aluminide coating, effectively shielding the substrate.</div></div>\",\"PeriodicalId\":22009,\"journal\":{\"name\":\"Surface & Coatings Technology\",\"volume\":\"510 \",\"pages\":\"Article 132236\"},\"PeriodicalIF\":5.3000,\"publicationDate\":\"2025-05-03\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Surface & Coatings Technology\",\"FirstCategoryId\":\"88\",\"ListUrlMain\":\"https://www.sciencedirect.com/science/article/pii/S0257897225005109\",\"RegionNum\":2,\"RegionCategory\":\"材料科学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q1\",\"JCRName\":\"MATERIALS SCIENCE, COATINGS & FILMS\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Surface & Coatings Technology","FirstCategoryId":"88","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0257897225005109","RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"MATERIALS SCIENCE, COATINGS & FILMS","Score":null,"Total":0}
Microstructure and oxidation behavior of the aluminized coating on K447A nickel-based superalloy prepared by AlF3-activated pack cementation
The function of AlF3 activator, the aluminized coating formation mechanism on K447A nickel-based superalloy during the pack cementation process, and their oxidation behaviors have been systematically investigated. Comprehensive characterization by XRD, SEM, TEM and EDS analyses with HSC thermochemical calculation reveals four key findings: AlF3 demonstrates the optimal aluminizing capability and generates active Al atoms via the disproportionation reaction of AlF gas. The aluminized coating exhibits a multilayer structure, with the outer layer composed of high Al content Ni2Al3 or NiAl3 and the inner layer consisting of NiAl. Precipitated phases such as α-(Cr, W), σ phase, and carbides are distributed in the aluminides, confirming an Al-dominated inward diffusion mechanism characteristic of a “high-activity” process. The coating thickness exhibits linear relationships to the reciprocal of temperature and holding time. Ni₂Al₃ is formed before NiAl, transforms into NiAl, and then is regenerated. After oxidizing at 1150 °C for 100 h, a protective ridged α-Al2O3 scale forms on the aluminide coating, effectively shielding the substrate.
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.