Inhibitor Coatings against High Temperature Corrosion

本发明的主要目的是详细说明所描述的新型涂层方法，其可以防止在陆地、海洋和航空涡轮机发动机和燃烧低质量燃料的化学过程中经常观察到的高温下的存款腐蚀。新的，提出的抑制剂涂层应通过修改纳米或微米级颗粒的扩散涂层。所追求的涂层将由典型的扩散涂层（例如铝化物）的基质组成，其中抑制剂或盐介导颗粒或两种颗粒的组合随机分布。这种涂层的优点是，当腐蚀性物质如硫酸盐或钒酸盐溶解原本保护性的氧化铝垢时，盐与添加的颗粒接触。抑制剂颗粒将被牺牲以形成高熔点物质，或者腐蚀将通过酸度的变化而被延迟，从而使熔体的侵蚀性降低。主要目的是通过研究涂层的效率及其耐化学性以及潜在的腐蚀机制来测试这种新方法。作为参考，将使用通过低活性包渗法制造的工业最新技术水平的未改性扩散涂层。涂层将暴露在两种盐沉积物下，这两种盐沉积物代表钒酸盐增强（60%V2O5-40%Na2SO4盐）和经典Na 2SO 4 II型腐蚀长达1000小时。此外，将进行循环氧化试验，以确认修改本身是否会影响寿命，例如通过诱导裂纹。将对不同试验的不同短期、中期和长期（长达1000小时）暴露样品进行详细调查。

The main goal of the present proposal is to elaborate the described novel coating approach, which can prevent the deposit corrosion at high temperatures often observed in land, marine, and aero turbine engines and chemical processes firing low quality fuels. The novel, proposed inhibitor coating should be obtained by modifying diffusion coatings with nano- or microscale particles. The pursued coatings will consist of a matrix of a typical diffusion coating such as aluminide in which inhibitor or salt mediating particles or combinations of both particles are randomly distributed. The advantage of such coatings is that, when corrosive substances such as sulphates or vanadates dissolve the otherwise protective alumina scale, the salt comes in contact with the added particles. The inhibitor particles will be sacrificed to form high-melting species or the corrosion will be retarded by a change in the acidity, making the melt less aggressive. The major objective is to test this new approach by investigating the efficiency of the coating and its chemical resistance as well as the underlying corrosion mechanisms. As a reference, an industrial state of the art, non-modified diffusion coating manufactured by low activity pack cementation will be used. The coatings will be exposed under two salt deposits that represent vanadate-enhanced (60%V2O5-40%Na2SO4 salt) and classical Na2SO4 type II corrosion for up to 1000h. In addition, cyclic oxidation tests will be performed to validate if the modifications themselves would affect the lifetime, e.g. by inducing cracks. Detailed investigation of the different short-, medium-, and long-term (up to 1000h) exposed samples of the different tests will be carried out.