## 3 Results and Discussion
### Comparison of Corrosion Resistance of Different Samples  
Figure 7 shows the Tafel polarization curves of 3D-printed, polished, 3D-printed + corroded (corrosion for 15 h, standing for 15 days), and 3D-printed + modified samples immersed in simulated seawater for 2 h. The corrosion characteristic parameters calculated by fitting are shown in Table 1.  
The polarization curves of the four samples in Figure 7 are arranged from right to left: 3D-printed + modified, 3D-printed + corroded, polished, and 3D-printed sam \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Parameters** & **3D Printed** & **Polished** & **3D Printed + Coroded** & **3D Printed + Modified** \\ \hline \(\mathrm{I_{corr}}\) (\(\mu\)A\(\cdot\)cm\({}^{-2}\)) & 8.953 & 2.834 & 0.34 & 0.165 \\ \(\mathrm{E_{corr}}\) (V) & \(-\)0.453 & \(-\)0.383 & \(-\)0.239 & \(-\)0.235 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Corrosion characteristic parameter table of different samples. Figure 6: Contact angle of 3D-printed + corrosion samples placed outdoors for different times. (**a**) 5 days; (**b**) 10 days; (**c**) 15 days. Figure 7: Tafel polarization curves of different samples. ples. The more to the right, the higher the corrosion potential, the greater the resistance to corrosion, and the better the corrosion resistance. Observing the specific values of corrosion current density and corrosion potential is shown in Table 1. In terms of corrosion potential, the 3D-printed sample is \(-0.453\) V, the polished sample is \(-0.383\) V, the 3D-printed + corroded sample is \(-0.239\) V, and the 3D-printed + modified sample is \(-0.235\) V; the value increases successively, indicating the corrosion resistance increases successively. In terms of corrosion current density, the 3D-printed sample is \(8.953\)\(\mu\)A\(\cdot\)cm\({}^{-2}\), the polished sample is \(2.834\)\(\mu\)A\(\cdot\)cm\({}^{-2}\), the 3D-printed + corroded sample is \(0.34\)\(\mu\)A\(\cdot\)cm\({}^{-2}\), and the 3D-printed + modified sample is \(0.165\)\(\mu\)A\(\cdot\)cm\({}^{-2}\); the value decreases successively, and the corrosion resistance increases successively. From the perspective of corrosion potential and corrosion current density, it can be concluded that the corrosion resistance of the four samples is ranked from strong to weak: the 3D-printed + modified sample > the 3D-printed + corroded sample > the polished sample > the 3D-printed sample. This is consistent with the results obtained by [PERSON] [27], and both confirm that the surface of the chemically modified 3D printing material has good corrosion resistance. Due to the strong polarization of the entire corrosion system during the polarization curve measurement process, it will cause greater interference to the system, bring errors to the measurement results, and lack the description of the behavior of the corrosion interface. For this reason, we continued to measure the impedance spectra of different samples. Figure 8 shows the Nyquist curves of polished, 3D-printed, 3D-printed + corroded, and 3D-printed + modified samples immersed in simulated seawater for 2 h. It can be clearly seen from the figure that the arc radius of 3D-printed, polished, 3D-printed + corroded, and 3D-printed + modified samples gradually increases, indicating that the resistance of charge transfer is increasing, and the corrosion resistance of the sample is increasing. It can be judged that the order of corrosion resistance from strong to weak is the 3D-printed + modified sample > the 3D-printed + corroded sample > polished sample > the 3D-printed sample, which is consistent with the test results of the polarization curve. Figure 9 is the Bode diagram of four samples. The impedance modulus at the low frequency of the Bode diagram can reflect the corrosion resistance of the material. The larger the impedance modulus value, the stronger the corrosion resistance.