| 摘要: |
| Cr-O-C 钝化层可以提高精密电铸脱模精度，但 Cr-O-C 钝化层对基底表面的钝化规律和对表层的影响尚未清楚。利用分子动力学方法，在多晶 Cu 表面沉积离散的 Cr、O 和 C 原子，获得不同比例和数量的 Cr-O-C 钝化层。计算结果表明，不同比例的 Cr、O 和 C 原子均可以大幅降低多晶 Cu 的表面能；随着原子数量的增加，多晶 Cu 的表面能呈下降趋势；Cr-O-C 钝化层增加了多晶 Cu 表层的位错密度；新增加的位错以 Shockley 位错为主；在一定沉积原子数量内，位错密度有极值。在多晶 Cu 表面电沉积不同密度的 Cr、O 和 C 原子，通过接触角测试验证了 Cr-O-C 钝化层降低多晶 Cu 表面能的结论。电沉积脱模强度和脱模表面粗糙度结果显示，随着沉积原子数的增加，脱模强度和脱模表面粗糙度均降低。研究结果可为利用离散 Cr-O-C 界面辅助精密电铸脱模提供一种解释。 |
| 关键词: Cr-O-C 界面 多晶 Cu 表面能 位错 脱模 分子动力学 |
| DOI：10.11933/j.issn.1007-9289.20230308002 |
| 分类号:TG113 |
| 基金项目:国家自然科学基金（52175407） |
|
| Demolding Strength and Demolding Accuracy Based on Surface Energy and Surface Layer Dislocations of Polycrystalline Cu Changed by Cr-O-C Passivation Layers |
|
TIAN Zhenqi, YANG Guang, CHEN Ju, LI Bo
|
|
College of Marine Equipment and Mechanical Engineering, Jimei University, Xiamen 361021 , China
|
| Abstract: |
| With the rapid development of new energy and energy-saving technologies, media, and information technology, the demand for high-end microstructure optical film materials has increased recently. Therefore, the surface roughness and shape position errors of a microstructure must be less than 10 nm. The electroforming error of the microstructure optical mold is primarily caused by plastic deformation during electroforming demolding. The Cr-O-C interface formed by the discrete Cr nuclei can assist in demolding. Because the passivation patterns of Cr, O, and C atom ratios and quantities on the substrate surface and the effect on the substrate surface layer are not fully understood, we used molecular dynamics methods to deposit discrete Cr, O, and C atoms on a polycrystalline Cu surface to obtain Cr-O-C passivation layers with different ratios and quantities of Cr, O, and C atoms. The surface energy of Cu/Cr-O-C was calculated using the classical embedded atom potential and the Lennard–Jones potential. The model utilizes the embedded atomic potential (EAM) to describe the interactions between Cu-Cu and Ni-Ni atoms, the interatomic interactions of Cr-Cr use the modified embedded atomic potential (MEAM), and the atomic potentials between Cu-Ni, Cr-Cu, Cr-Ni, O-O, O-Cu, O-Ni, O-Cr, C-C, C-Cu, C-Ni, C-Cr, and C-O use the classical Lennard–Jones potential. Before performing the calculations, an energy minimization command was employed to eliminate any structurally unsound entities during the modeling process. The relaxation time in the NVT system was 25 ps. The simulation results were subjected to visual analysis using the software OVITO. Commands, such as the dislocation extraction algorithm (DXA), were used to extract the crystal structure and dislocation changes from the models. The local crystal structures around the atoms were identified using common neighborhood analysis (CNA). Using a controlled sedimentation potential, we deposited different numbers of Cr nuclei on the surface of polycrystalline Cu via electrodeposition. Contact-angle measurements were performed on several Cu surfaces. Meanwhile, 0.5 mm-thick Ni layers were electrodeposited on Cu surfaces containing different deposition quantities of discrete Cr-O-C nuclei. After electroforming the Ni layer, the stripping strength of the Cu/Cr-O-C/Ni complex was tested and the surface roughness of the Ni layer was measured using a confocal laser microscope. The calculated results showed that different ratios of Cr, O, and C atoms significantly reduced the surface energy of polycrystalline Cu. The surface energy of polycrystalline Cu tended to decrease as the number of atoms increased, and the Cr, O, and C atoms also increased the dislocation density of the polycrystalline Cu surface layer. The newly added dislocations were dominated by Shockley dislocations, and the dislocation density exhibited extreme values for a certain number of deposited atoms. The conclusion that Cr, O, and C atoms reduced the surface energy of polycrystalline Cu was confirmed using contact angle tests. The results of the electrodeposition demolding strength and demolding surface roughness tests showed that they decreased with an increase in the number of deposited atoms. Therefore, surface modification of the original mold can reduce the plastic deformation during demolding, which is closely related to the control of the interface bonding strength. These results provide a possible explanation for the use of discrete Cr-O-C interfaces to assist in the interpretation of precision electroforming demolding. The bonding strength between the polycrystalline Cu substrate and the electroformed Ni layer involves several physical and chemical factors, and molecular dynamics methods enable us to understand the mechanism by which the anti-adhesion layer regulates the bonding force. |
| Key words: Cr-O-C interface polycrystalline Cu surface energy dislocations demolding molecular dynamics |
