|ZHANG Xiang,MA Xiaogang,ZHANG Liang,YANG Shirui,XIE Zhiwen.Application of the Dealloying Method to the Grinding and Finishing of TC4 Titanium Alloy Magnetic Particles[J].China Surface Engineering,2023,36(2):189~199
|为解决 TC4 钛合金表面材料的定量去除问题，提高 TC4 钛合金磁粒研磨光整加工的效率，采用电化学脱合金法对不同浓度的 NaOH 溶液进行分析，得出最佳电解液浓度为 1.5 mol / L；利用动电位和恒电位极化确定脱合金临界电压为 2.1 V。 在 1.5 mol / L NaOH 溶液中，2.1 V 电压下进行脱合金试验， TC4 钛合金表面获得连续均匀的纳米多孔结构。脱合金 3、6、 9 h 后，工件表面纳米多孔层的维氏硬度分别降低 29.4%、39.5%、46.7%。摩擦磨损试验中，磨球穿透纳米多孔层的时间分别为 11、21、35 min，纳米多孔层厚度分别达到 2.2、3.8 和 6.2 μm。对 TC4 钛合金和脱合金工件进行磁粒研磨光整加工，研磨加工 165 min 后，TC4 钛合金表面 6.2 μm 厚度的磨痕得到有效去除；研磨加工 45 min 后，脱合金工件表面 6.2 μm 厚度的纳米多孔层被有效去除，研磨效率提升 72.7%。使用脱合金-磁粒研磨复合加工的方法，实现了 TC4 钛合金表面材料的定量去除，而且降低了表面材料的维氏硬度，提高了磁粒研磨的加工效率。
|关键词: TC4 钛合金 电化学脱合金 纳米多孔结构 维氏硬度 磁粒研磨 定量去除
|Application of the Dealloying Method to the Grinding and Finishing of TC4 Titanium Alloy Magnetic Particles
ZHANG Xiang1, MA Xiaogang1, ZHANG Liang2, YANG Shirui2, XIE Zhiwen1
1.College of Mechanical Engineering and Automation, University of Science and Technology Liaoning,Anshan 114051 , China;2.Beijing Power Machinery Research Instituted, Beijing 100074 , China
|This study attempted to solve the problem of quantitative removal of TC4 titanium alloy surface material and improve the efficiency of the lapping finishing process for TC4 titanium alloy magnetic particles by employing the electrochemical dealloying and magnetic particle lapping methods. The electrochemical dealloying method was used to analyze the corrosion range of the TC4 titanium alloy in 0.5, 1, and 1.5 mol / L NaOH solutions, and it was determined that when the electrolyte concentration was 1.5 mol / L, the corrosion interval was large and the corrosion and dissolution of the Al element was obvious. In electrochemical dealloying experiments, the dealloying behavior was characterized by potentiodynamic and potentiostatic polarization. The range of critical voltage determined by potentiodynamic polarization is 0.5-2.3 V. The influence of the scanning rate was then excluded by potentiostatic polarization, and the accurate critical voltage of dealloying was determined to be 2.1 V. Electrochemical dealloying experiments were conducted on TC4 titanium alloy workpieces in 1.5 mol / L of NaOH solution at 2.1 V. Scanning electron microscopy revealed that a nanoporous structure with large pores and continuous uniformity was prepared on the surface of the TC4 titanium alloy after electrochemical dealloying. With the prolongation of the electrochemical dealloying test time, the Al element continued to dissolve rapidly and continuously. The dealloying process penetrated deep into the interior of the TC4 titanium alloy, and the thickness of the nanoporous layer also increased. After electrochemical dealloying of the TC4 titanium alloy for 3, 6, and 9 h, the Vickers hardness of the nanoporous layer on the surface was detected by a microhardness tester under the same test conditions. Results showed that, compared with the TC4 titanium alloy, the Vickers hardness of the nanoporous layer on the surfaces of the workpieces after dealloying was reduced by 29.4%, 39.5%, and 46.7%, respectively. A friction test using a friction and wear tester was performed on the workpieces after dealloying and revealed that the grinding ball penetrated the nanoporous layers prepared on the workpiece surfaces after dealloying for 3, 6, and 9 h, and the times for the friction factor to jump were 11, 21, 35 min, respectively. The thickness of the nano-porous layer on the surfaces of the dealloyed workpieces was measured using a step instrument. The measurement data showed that the thickness of the nano-porous layer on the surface of the TC4 titanium alloy could reach 2.2, 3.8, and 6.2 μm after 3, 6, and 9 h of dealloying, respectively. Finally, the TC4 titanium alloy and dealloyed workpieces were subjected to magnetic particle grinding and finishing tests. After 165 min of magnetic particle grinding, the 6.2-μm-thick wear scars on the surface of the TC4 titanium alloy were effectively removed; after 45 minutes, the 6.2 μm thick wear scar on the surface of the dealloyed workpiece was effectively removed, the nano porous layer was quantitatively removed, and the magnetic particle grinding efficiency was improved by 72.7%. In addition, a comparison of the Vickers hardnesses of the workpiece surfaces before and after grinding showed that the dealloying reaction corroded and dissolved the surface layers of the workpieces, which decreased the surface hardnesses of the workpieces but did not affect the performance of the TC4 titanium alloy matrix. Thus, dealloying-magnetic particle grinding composite processing enables the quantitative removal of the surface material of the TC4 titanium alloy, and the processing efficiency of magnetic particle grinding can be improved by reducing the Vickers hardness of the surface material. This processing technology can provide a reference for the quantitative removal of surface materials while ensuring the grinding efficiency of cemented carbide.
|Key words: TC4 titanium alloy electrochemical dealloying nanoporous structure vickers hardness magnetic particle grinding quantitative removal