Effects of heating temperature and duration on the microstructure and properties of the self-healing coatings

Effect of TiC self-healing coatings on the cyclic oxidation resistance and lifetime of thermal barrier coatings

“…The self-healing effect of TiC coatings has been studied in previous works [19][20][21]. According to the statistic of porosity of specimens before and after self-healing heat treatment, the self-healing process could promote the cracks and pores being filled.…”

“…[18] However, the detailed investigation about the application of self-healing material in TBC has not been studied. The previous study results on TiC [19][20][21] indicated that it could be a qualified self-healing agent in APS-coatings and also compatible with Al 2 O 3 . In our previous work [21], the self-healing effect of TiC can reduce the porosity of coatings from 4.43% to 0.46% resulting in the significant reduction of cracks and pores.…”

“…According to the previous study, TiC can act as a self-healing agent, which means that it could be oxidized to TiO 2 at 600℃ for 5 hours [19]. Therefore, all of these TiC-self-healing TBCs were treated similarly and self-healing agent could release its oxide (TiO 2 ) completely during this treatment.…”

Self-healing coatings in anti-corrosion applications

“…Ceramic materials (TiC/Al 2 O 3 and Ti 2 AlC) are used for self-healing coatings. In this case, self-healing is activated by an increase in temperature, resulting in the oxidation of the coating components and in the filling of the defects by titanium and aluminium oxides [119,120].…”

YSZ- Ti3AlC2 Thermal Barrier Coating and Its Self-healing Behavior under High Temperatures

“…无 机 材 料 学 报 第 32 卷 热致生长氧化物层(TGO)是涂层裂纹产生的主 要源头与扩散通道, TGO 的过度生长会使 TGO/粘 结层和 TGO/陶瓷层界面处聚集较大的残余应力, 从而产生横向裂纹, 这是造成陶瓷层脱落的一个主 要因素 [2] 。 在 TBCs 中添加一定量的自愈合剂, 通过 氧化愈合裂纹可以有效阻止氧气的渗透, 抑制 TGO 的生长速度, 提高涂层的使用寿命 [3] 。 对于各类自愈 合材料, Vand 等 [4] 进行了一定的总结, 他们认为由于 陶瓷材料本身的强共价键, 陶瓷材料需要通过高温 氧化生成氧化物来达到"愈合"效果。陶瓷的自愈 合应至少满足下列一点：(1)生成的氧化物具有良好 的物理性能, 能够改善并恢复基体性能; (2)生成的氧 化物不具有良好的物理性能, 但氧化时具有体积膨 胀效应, 从而填补裂纹及缺陷。满足上述性能要求的 自愈合剂材料目前有 SiC 和 Si 3 N 4 , 它们在高温氧化 过程中生成的 SiO 2 是良好的愈合材料 [5] , 但在实际 应用环境中 SiO 2 会与水蒸气反应, 生成易挥发的 Si(OH) 4 , 削弱对裂纹的填充。而 MoSi 2 和 CrMoSi 等块体材料虽然具有一定自愈合能力, 且氧化后能 继续与 ZrO 2 反应生成硅酸锆, 然而其存在低温粉化 现象, 即未填充裂纹便有部分愈合剂力学性能劣化, 从而与基质材料失去结合能力 [6] 。此外, 加入 Si 元 素将在一定程度上促进涂层的高温烧结, 增加其弹 性模量, 提高涂层的应力水平, 降低涂层的服役性 能。 TiC 作为自愈合材料, 在氧化过程中通过体积膨 胀填充裂纹, 但填充物多以颗粒形态出现, 无法有 效屏蔽氧气渗入, 所以在制备自愈合涂层时需要混 合一定量的 Al 2 O 3 粉末, 以提高对氧气的隔绝能 力 [7][8] 。因此, 自愈合热障涂层的有效应用在于填充 裂纹的同时能形成对氧气的阻隔。通过对潜在自愈 合材料的筛选, Ti 3 AlC 2 可满足上述要求。Ti 3 AlC 2 属 于三元层状化合物 [9] , 既具有金属的性能又具有陶 瓷的性能。Lee 等 [10]…”