Kim Dasom, Hirayama Yusuke, Takagi Kenta, Kwon Hansang
Department of Materials System Engineering, Pukyong National University, 365, Sinseon-ro, Nam-gu, Busan 48513, Korea.
Magnetic Powder Metallurgy Research Center, The National Institute of Advanced Industrial Science and Technology (AIST), 2266-98, Anagahora, Shimoshidami, Moriyama-ku, Nagoya 463-8560, Japan.
Materials (Basel). 2022 Feb 18;15(4):1553. doi: 10.3390/ma15041553.
The development of bare metal powder is desirable for obtaining conductive interfaces by low-temperature sintering to be applied in various industries of 3D printing, conductive ink or paste. In our previous study, bulk Al made from Al nanopowder that was prepared with low-oxygen thermal plasma (LO-ITP), which is the original metal powder production technique, showed high electrical conductivity comparable to Al casting material. This study discusses the surface cleaning effect of Al particles expected to be obtained by peeling the surface of Al particles using the LO-ITP method. Bare metal micro-sized powders were prepared using LO-ITP by controlling the power supply rate and preferentially vaporizing the oxidized surface of the Al powder. Electrical conductivity was evaluated to confirm if there was an oxide layer at the Al/Al interface. The Al compact at room temperature produced from LO-ITP-processed Al powder showed an electrical conductivity of 2.9 · 10 S/m, which is comparable to that of cast Al bulk. According to the microstructure observation, especially for the interfaces between bare Al powder, direct contact was achieved at 450 °C sintering. This process temperature is lower than the conventional sintering temperature (550 °C) of commercial Al powder without any surface cleaning. Therefore, surface cleaning using LO-ITP is the key to opening a new gate to the powder metallurgy process.
开发裸金属粉末对于通过低温烧结获得导电界面非常有必要，以便应用于3D打印、导电油墨或浆料等各个行业。在我们之前的研究中，用低氧热等离子体（LO-ITP）制备的铝纳米粉末制成的块状铝，这是原始的金属粉末生产技术，其电导率与铸造铝材料相当。本研究讨论了预期通过使用LO-ITP方法剥离铝颗粒表面而获得的铝颗粒的表面清洁效果。通过控制电源速率并优先蒸发铝粉的氧化表面，使用LO-ITP制备了裸金属微米级粉末。通过评估电导率来确认铝/铝界面处是否存在氧化层。由LO-ITP处理的铝粉在室温下制成的铝坯块的电导率为2.9·10 S/m，与铸造铝块相当。根据微观结构观察，特别是对于裸铝粉之间的界面，在450℃烧结时实现了直接接触。该工艺温度低于未经任何表面清洁的商业铝粉的传统烧结温度（550℃）。因此，使用LO-ITP进行表面清洁是打开粉末冶金工艺新大门的关键。
