Meng Qian, Lai Lin, Rao Wan, Li An, Yu Haicun, La Peiqing
School of Materials Science and Engineering, Lanzhou University of Technology, Lanzhou 730050, China.
School of Materials Science and Engineering, Lanzhou Jiaotong University, Lanzhou 730070, China.
Materials (Basel). 2024 Dec 13;17(24):6108. doi: 10.3390/ma17246108.
Molten carbonate salts are a promising candidate for next-generation concentrated solar power technology owing to their excellent heat storage and heat transfer properties. This represents overcoming several problems that structural materials exhibit, including severe corrosion and high-temperature creep. Alloys with an aluminum element are alternatives in this regard as they are highly resistant to corrosive environments. In this paper, the corrosion behavior in molten carbonates (LiCO-NaCO-KCO) and creep properties of TP347H with different aluminum contents at 650 °C were studied. The results demonstrated that the alloy corrosion rate was reduced via Al addition. The alloy with 2.5 wt.% Al exhibited the lowest corrosion rate: ~25% lower than that without Al after 1000 h of corrosion. With increasing Al content, the inner corrosion layer of the alloys transformed from a Cr-containing oxide layer to a Cr-Al-containing composite oxide layer. The addition of Al promoted the formation of a layer of continuous and dense LiFeO product on the alloy surface during early corrosion stages, which prevented the carbonate from coming into direct contact with the substrate. After 1000 h of corrosion, the surface of the alloy is mainly composed of LiFeO and LiCrO. Compared to TP347H, the added Al element enhanced the strength and elongation of TP347H at 650 °C. The TP347H containing 2 wt.% Al exhibited the best high-temperature tensile properties. When the stress was 110 MPa, the lowest steady-state creep rate of the alloy containing 2 wt.% Al was 3.61 × 10, and the true stress index was 5.791. This indicates that the creep mechanism was a dislocation climb assisted by lattice diffusion.
熔融碳酸盐由于其出色的储热和传热性能，是下一代聚光太阳能发电技术的一个有前景的候选材料。这意味着克服了结构材料所表现出的几个问题，包括严重腐蚀和高温蠕变。含铝元素的合金在这方面是替代材料，因为它们对腐蚀性环境具有高度抗性。本文研究了不同铝含量的TP347H在650℃下在熔融碳酸盐（LiCO-NaCO-KCO）中的腐蚀行为和蠕变性能。结果表明，通过添加铝降低了合金腐蚀速率。含2.5 wt.%铝的合金表现出最低的腐蚀速率：腐蚀1000小时后比不含铝的合金低约25%。随着铝含量的增加，合金的内腐蚀层从含铬氧化物层转变为含铬铝复合氧化物层。在早期腐蚀阶段，铝的添加促进了合金表面形成一层连续致密的LiFeO产物，这防止了碳酸盐与基体直接接触。腐蚀1000小时后，合金表面主要由LiFeO和LiCrO组成。与TP347H相比，添加的铝元素提高了TP347H在650℃下的强度和伸长率。含2 wt.%铝的TP347H表现出最佳的高温拉伸性能。当应力为110 MPa时，含2 wt.%铝的合金的最低稳态蠕变速率为3.61×10，真应力指数为5.791。这表明蠕变机制是由晶格扩散辅助的位错攀移。
