Abstract Corrosion of process equipment during ammonothermal synthesis at high temperature and pressure is still one of the big limitations of this process because of reduced crystal quality and safety issues. In this paper we present preliminary ammonothermal corrosion experiments with two Ni-base superalloys (Inconel®Alloy 718 and Haynes®282®Alloy) and two newly developed Co-base superalloys (CoWAlloy1&2) in a supercritical NH3/NH4Cl-solution (24 h/550 °C/105 MPa). After the experiment, the samples were analyzed by their mass change per initial surface area (specific weight change). Additionally, the morphological and elemental changes of the corrosion layers were evaluated. None of the investigated alloys developed a passivation layer and the corrosion layers were very fragile. In agreement with previous studies, the Ni-base alloys showed intergranular attack with severe general corrosive degeneration. Despite their high potential for high-pressure at high-temperature applications and in contrast to a ternary Co-Al-W-alloy, the investigated multinary Co-base alloys were strongly attacked, too. However, CoWAlloy2 presented the lowest specific weight change of the investigated alloys. Thus, it shows the best potential for application in acidic environment of the investigated alloys. Additionally, CoWAlloy2 proved good stability in a supercritical NH3/Na-solution (24 h/550 °C/93 MPa).

中文翻译：

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Inconel®Alloy 718、Haynes®282®Alloy 和 CoWAlloy1&2 在超临界氨/氯化铵溶液中的高温腐蚀

摘要 由于降低了晶体质量和安全问题，高温高压氨热合成过程中工艺设备的腐蚀仍然是该工艺的一大局限。在本文中，我们介绍了两种镍基高温合金（Inconel®Alloy 718 和 Haynes®282®Alloy）和两种新开发的钴基高温合金（CoWAlloy1&2）在超临界 NH3/NH4Cl 溶液中（24 小时/ 550 °C/105 兆帕）。实验后，通过每个初始表面积的质量变化（比重变化）分析样品。此外，还评估了腐蚀层的形态和元素变化。所研究的合金都没有形成钝化层，并且腐蚀层非常脆弱。与以往的研究一致，镍基合金显示出严重的普遍腐蚀退化的晶间侵蚀。尽管它们在高温应用中具有很高的高压潜力，并且与三元 Co-Al-W 合金相比，所研究的多元 Co-基合金也受到了强烈的攻击。然而，CoWAlloy2 呈现出所研究合金的最低比重变化。因此，它显示了所研究合金在酸性环境中的最佳应用潜力。此外，CoWAlloy2 在超临界 NH3/Na 溶液 (24 h/550 °C/93 MPa) 中证明了良好的稳定性。CoWAlloy2 呈现出所研究合金的最低比重变化。因此，它显示了所研究合金在酸性环境中的最佳应用潜力。此外，CoWAlloy2 在超临界 NH3/Na 溶液 (24 h/550 °C/93 MPa) 中证明了良好的稳定性。CoWAlloy2 呈现出所研究合金的最低比重变化。因此，它显示了所研究合金在酸性环境中的最佳应用潜力。此外，CoWAlloy2 在超临界 NH3/Na 溶液 (24 h/550 °C/93 MPa) 中证明了良好的稳定性。