Preparing an ultra-smooth TaW alloy surface with chemical mechanical polishing via controlling galvanic corrosion

• Published in: Journal of applied electrochemistry Vol. 54; no. 4; pp. 839 - 850
• Main Authors: Zhao, Qijian, Tian, Chuandong, Zheng, Jiaxin, Sun, Pengfei, Jiang, Liang, Qian, Linmao
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01-04-2024; Springer Nature B.V
• Subjects: Alloys; Chemical bonds; Chemical-mechanical polishing; Chemistry; Chemistry and Materials Science; Corrosion prevention; Electrochemistry; Galvanic corrosion; Hydrogen peroxide; Industrial Chemistry/Chemical Engineering; Material removal rate (machining); Physical Chemistry; Research Article; Substrates; Surface properties; Surface roughness; Tantalum; Tantalum base alloys; Tantalum oxides; Tantalum alloy; Surface quality; Coating; Ultra-smooth; Chemical mechanical polishing
• ISSN: 0021-891X; 1572-8838
• DOI: 10.1007/s10800-023-01986-w

An ultra-smooth tantalum alloy surface is essential to prepare a high-quality coating. This work employed the chemical mechanical polishing (CMP) technique to process Ta-12W alloy. The effect of H
2
O
2
on the CMP performance was investigated. The results revealed that, as the H
2
O
2
concentration increases at acidic pH, the material removal rate (MRR) of Ta-12W alloy gradually increases while the surface roughness sharply decreases and levels off. After adding 4 wt% H
2
O
2
, the surface roughness
S
a
reaches about 0.4 nm in 97.9 μm × 97.9 μm and 0.068 nm in 1 μm × 1 μm. The surface becomes ultra-smooth, and the substrate remains intact. For the CMP mechanism, adding H
2
O
2
can promote the formation of a relatively uniform and passive film, mainly consisting of evenly distributed tantalum oxides and tungsten oxides, suppressing corrosion. Therefore, the surface quality improves. Compared with hard metallic tantalum and tungsten, their oxides can be removed readily by silica abrasive particles presumably through chemical bonds and mechanical abrasion. Hence, the MRR increases. Additionally, potassium ions may contribute to the removal of tantalum. This study provides a feasible method to attain tantalum alloys of high surface quality for coating.
Graphical Abstract