Effect of holding time on the microstructure evolution of titanizing coating on 09CrCuSb steel

IF 6.1 2区材料科学 Q1 MATERIALS SCIENCE, COATINGS & FILMS

Surface & Coatings Technology Pub Date : 2025-09-22 DOI:10.1016/j.surfcoat.2025.132720

Wenhao Jin , Yue Guo , Huixuan Zhang , Fangqin Dai , Ting Liu

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Abstract

ND steel (09CrCuSb steel), as a material resistant to sulfuric acid dew point corrosion, still faces severe corrosion during long-term service in low-temperature sulfur-containing flue gas environments. Titanium possesses excellent passivation characteristics which is widely used in surface coatings for iron-based materials. The phases and microstructure of titanizing coatings are crucially important for its corrosion resistance. However currently, there are very few studies on the growth evolution of phases and morphologies, which is explored by this study using the powder pack cementation method, with a pack mixture of Ti powder, NH₄Cl, and Al₂O₃ at 1020 °C for 1–4 h. Its phase and microstructure were characterized by SEM, XRD, and EPMA to reveal the evolution mechanisms of titanizing coating. Results show that “ant-hole-like” pores and irregular net-like protrusions formed on the coating surface, which gradually grows and extends with holding time. The titanizing coating consists of Ti-poor layer, “needle-like” transition layer, Ti-rich layer, and subsurface particles. The formation of transition layer is closely associated with the coating micropores and the cyclic reactions induced by elemental diffusion, which thickness increases significantly with holding time. The main phases of coating include Ti₄Fe₂O, TiAl₃, TiN, AlN, TiFe, and FeAl compounds, and there are point-like particles of TiN and AlN in the substrate subsurface.

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保温时间对09CrCuSb钢渗钛涂层组织演变的影响

ND钢（09CrCuSb钢）作为耐硫酸露点腐蚀的材料，在低温含硫烟气环境中长期使用，仍然面临着严重的腐蚀问题。钛具有良好的钝化特性，广泛应用于铁基材料的表面涂层。渗钛涂层的相和显微组织对其耐蚀性至关重要。但目前对钛粉、NH₄Cl和Al₂O₃的包埋混合物在1020℃下保温1 ~ 4 h，采用粉末包埋法进行了相和形貌的生长演化研究，通过SEM、XRD和EPMA对其相和微观结构进行了表征，揭示了钛化涂层的演化机理。结果表明：涂层表面形成了“蚁孔”状孔隙和不规则的网状突起，并随着保温时间的延长逐渐增大和延伸；镀钛层由贫钛层、“针状”过渡层、富钛层和亚表面颗粒组成。过渡层的形成与涂层微孔和元素扩散引起的循环反应密切相关，随着保温时间的延长，过渡层的厚度显著增加。涂层的主要相有Ti4Fe2O、TiAl3、TiN、AlN、TiFe和FeAl化合物，衬底亚表面存在TiN和AlN的点状颗粒。

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.