Seo Bosung, Park Hyung-Ki, Park Chang-Soo, Kim Seongtak, Park Kwangsuk
Gangwon Regional Division, Korea Institute of Industrial Technology, Gangneung-si 25440, Gangwon-do, Republic of Korea.
Materials (Basel). 2023 Sep 15;16(18):6217. doi: 10.3390/ma16186217.
Further improving the corrosion resistance of the ASTM Grade 13 (Gr13) titanium alloy was achieved by manipulating the cathodic modification effect. The cathodic modification of Gr13 was mainly related to the TiNi precipitate, where minor Ru was contained and controlled the precipitate in terms of size and distribution, which could manipulate the cathodic modification effect. Parameters such as temperature and cooling rate during the recrystallization process were designed to control precipitation behavior, where the temperature at 850 °C was selected to allow the full dissolution of the TiNi precipitate. The cooling rate, as high as 160.9 °C/min, was still enough for precipitation to occur during the cooling stage, leading to the formation of the TiNi precipitate along with a grain boundary. The cooling rate of water quenching was too fast to cause the diffusion process, resulting in a large amount of the β-Ti phase without the precipitate, which was pre-formed while heated at 850 °C. Aging at 600 °C caused the re-precipitation of TiNi, and, at that moment, the precipitate was refined and separated, as a good aspect of the catalyst for HER. Therefore, the aged sample after water quenching showed the lowest onset potential for HER with the highest corrosion potential, indicating that its passivation ability was improved by the strengthened cathodic modification effect. This improvement was confirmed by the OCP results, where passivation survival was observed for the aged sample due to the highest cathodic modification effect. Therefore, the aged sample, which had refined and separate precipitates, showed the lowest corrosion rate.
通过控制阴极改性效应进一步提高了ASTM 13级（Gr13）钛合金的耐腐蚀性。Gr13的阴极改性主要与含微量Ru的TiNi析出物有关，Ru控制着析出物的尺寸和分布，从而可以控制阴极改性效应。设计了再结晶过程中的温度和冷却速率等参数来控制析出行为，选择850℃的温度以使TiNi析出物完全溶解。冷却速率高达160.9℃/min，在冷却阶段仍足以发生析出，导致沿晶界形成TiNi析出物。水淬的冷却速率太快，无法引起扩散过程，导致大量β-Ti相且无析出物，β-Ti相是在850℃加热时预先形成的。在600℃时效导致TiNi重新析出，此时，析出物细化并分离，这是析氢反应催化剂的一个良好方面。因此，水淬后的时效样品显示出析氢反应的最低起始电位和最高腐蚀电位，表明其钝化能力因增强的阴极改性效应而提高。开路电位结果证实了这种改善，由于具有最高的阴极改性效应，时效样品观察到了钝化存活。因此，具有细化和分离析出物的时效样品显示出最低的腐蚀速率。
