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Investigation of surface and thermogravimetric characteristics of carbon‐coated iron nanopowder
Surface and Interface Analysis ( IF 1.6 ) Pub Date : 2020-09-28 , DOI: 10.1002/sia.6878
Swathi K. Manchili 1 , Johan Wendel 1 , Yu Cao 1 , Eduard Hryha 1 , Lars Nyborg 1
Affiliation  

Demand for high-density press and sinter components is increasing day by day. Of the different ways to improve the sinter density, the addition of nanopowder to the conventional micrometer-sized metal powder is an effective solution. The present investigation is aimed at studying the surface chemistry of iron nanopowder coated with graphitic carbon, which is intended to be mixed with the conventional iron powder. For this purpose, iron nanopowder in the size range of 30 nm to submicron (less than 1 micron) was investigated using thermogravimetry at different temperatures: 400 degrees C, 600 degrees C, 800 degrees C, 1000 degrees C, and 1350 degrees C. The X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), and high-resolution scanning electron microscopy (HR-SEM) were used for characterizing the powder as well as samples sintered at different temperatures. The presence of iron, oxygen, carbon, chromium, and zinc were observed on the surface of the nanopowder. Iron was present in oxide state, although a small metallic iron peak at 707 eV was also observed in the XPS spectra obtained from the surface indicating the oxide scale to be maximum of about 5 nm in thickness. For the sample treated at 600 degrees C, presence of manganese was observed on the surface. Thermogravimetry results showed a two-step mass loss with a total mass loss of 4 wt.% when heated to 1350 degrees C where the first step corresponds to the surface oxide reduction.

中文翻译:

碳包覆铁纳米粉体的表面和热重特性研究

对高密度压机和烧结部件的需求与日俱增。在提高烧结密度的不同方法中,在常规微米级金属粉末中加入纳米粉末是一种有效的解决方案。目前的研究旨在研究涂有石墨碳的铁纳米粉末的表面化学,石墨碳旨在与常规铁粉混合。为此,在不同温度下使用热重法研究了尺寸范围为 30 nm 到亚微米(小于 1 微米)的铁纳米粉末:400 摄氏度、600 摄氏度、800 摄氏度、1000 摄氏度和 1350 摄氏度。 X射线光电子能谱(XPS)、俄歇电子能谱(AES)、和高分辨率扫描电子显微镜 (HR-SEM) 用于表征粉末以及在不同温度下烧结的样品。在纳米粉末的表面观察到铁、氧、碳、铬和锌的存在。铁以氧化物状态存在,尽管在从表面获得的 XPS 光谱中也观察到 707 eV 的小金属铁峰,表明氧化皮厚度最大约为 5 nm。对于在600℃下处理的样品,在表面观察到锰的存在。热重分析结果显示两步质量损失,当加热到 1350 摄氏度时,总质量损失为 4 wt.%,其中第一步对应于表面氧化物还原。在纳米粉体表面观察到锌。铁以氧化物状态存在,尽管在从表面获得的 XPS 光谱中也观察到 707 eV 的小金属铁峰,表明氧化皮厚度最大约为 5 nm。对于在600℃下处理的样品,在表面观察到锰的存在。热重分析结果显示两步质量损失,当加热到 1350 摄氏度时,总质量损失为 4 wt.%,其中第一步对应于表面氧化物还原。在纳米粉体表面观察到锌。铁以氧化物状态存在,尽管在从表面获得的 XPS 光谱中也观察到 707 eV 的小金属铁峰,表明氧化皮厚度最大约为 5 nm。对于在600℃下处理的样品,在表面观察到锰的存在。热重分析结果显示两步质量损失,当加热到 1350 摄氏度时,总质量损失为 4 wt.%,其中第一步对应于表面氧化物还原。在表面观察到锰的存在。热重分析结果显示两步质量损失,当加热到 1350 摄氏度时,总质量损失为 4 wt.%,其中第一步对应于表面氧化物还原。在表面观察到锰的存在。热重分析结果显示两步质量损失,当加热到 1350 摄氏度时,总质量损失为 4 wt.%,其中第一步对应于表面氧化物还原。
更新日期:2020-09-28
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