## 3 Results and Discussion
### Comparison of Corrosion Resistance of Different Samples
According to the test data, at low frequency f = 0.0178 Hz, the impedance modulus of the 3D-printed sample is \(6.3\times 10^{3}\)\(\Omega\cdot\)cm\({}^{2}\), the impedance modulus of the polished sample is \(1.27\times 10^{4}\)\(\Omega\cdot\)cm\({}^{2}\), the impedance modulus of the 3D-printed + corroded sample is \(9.6\times 10^{4}\)\(\Omega\cdot\)cm\({}^{2}\), and the impedance modulus of 3D-printed + modified sample is \(3.24\times 10^{5}\)\(\Omega\cdot\)cm\({}^{-2}\), and the impedance modulus becomes larger in turn. The corrosion resistance of the four samples is ranked as the 3D-printed + modified sample > the 3D-printed + corroded sample > the  
Figure 8: Nyquist plots of different samples. polished sample > the 3D-printed sample. The analysis results of the Tafel graph, Nyquist graph and Bode graph are consistent, and the measurement results of corrosion resistance can be considered reliable. In order to further explore the anti-corrosion mechanism of superhydrophobic surfaces and achieve a quantitative description of the charge transfer and material transfer during the corrosion process, ZSimpwin software was used to fit the measured impedance curve, and an equivalent circuit model was established with reference to relevant literature. As shown in Figure 10, for polished samples, the R (QR) model (Figure 10a) fits the measured curve best, the number of iterations Iter# is only 2 and the value of Chsq is 9.69 \(\times\) 10\({}^{-4}\), which is also very small; Rs represents the solution resistance, CPE represents the interface capacitance between the metal and the electrolyte solution, and Rct is the charge transfer resistance. The larger the value, the greater the resistance when the charge passes through the interface between the metal and the solution. For the impedance curve of 3D-printed samples, the R(C(R(QR))) model (Figure 10b) is the best fit. The number of iterations Iter# is 3 and the value of Chsq is 3.44 \(\times\) 10\({}^{-4}\). In this circuit model, Rp and Cp represent the resistance and capacitance of the microstructure layer, respectively. For the impedance curves of 3D-printed + corroded and 3D-printed + modified samples, the R(C(R(Q(RW)))) model (Figure 10c) is the best fit. The number of iterations Iter# is 4, The values of Chsq are 2.93 \(\times\) 10\({}^{-3}\) and 3.20 \(\times\) 10\({}^{-3}\), respectively. In this model, CPE represents the constant phase angle element associated with the electric double layer capacitance, andWs is the diffusion resistance of the solution. The element parameters in the equivalent circuit model fitted by Zsimpwin software are shown in Table 2. The charge transfer resistance Rct of 3D-printed, polished, 3D-printed + corroded, and 3D-printed + modified samples are 29,540 \(\Omega\)-cm\({}^{2}\), 75,550 \(\Omega\)-cm\({}^{2}\), 178,902 \(\Omega\)-cm\({}^{2}\), and 207,600 \(\Omega\)-cm\({}^{2}\), respectively; the value of charge transfer resistance increases successively, indicating that the corrosion resistance is successively enhanced. The value of electric double layer capacitor CPE-T can also show corrosion resistance. The smaller the value of CPE-T, the stronger the corrosion resistance. The CPE-T values of 3D-printed, polished, 3D-printed + corroded, and 3D-printed + modified samples are 89.52 \(\mu\)F-cm\({}^{2}\), 67.26 \(\mu\)F-cm\({}^{2}\), 20.76 \(\mu\)F-cm\({}^{2}\), and 6.64 \(\mu\)F-cm\({}^{2}\), respectively, and the values decreased sequentially. It also verified the correctness of the corrosion-resistance conclusion. Figure 9: Bode diagrams of different samples. The above experimental data show that the corrosion resistance of the surface of the 3D-printed + modified sample or the 3D-printed + corroded sample is greatly improved compared with the polished sample. The main reason for this phenomenon is closely related to the surface wettability.