| 弥散稀土氧化物改进的复合铝化物涂层抗高温氧化行为的研究 | |
| 马信清 | |
| Subtype | 硕士 |
| Thesis Advisor | 李铁藩 |
| 1990 | |
| Degree Grantor | 中国科学院金属腐蚀与防护研究所 |
| Place of Conferral | 中国科学院金属腐蚀与防护研究所 |
| Abstract | 本文采用Ni-R_2O_3共电沉积和后热扩散渗铝技术成功地制备了分别含有弥散稀土氧化物Y_2O_3, La_2O_3 and Gd_2O_3质点的NiAl-R_2O_3复合涂层，并重点研究了涂层中稀土氧化物的种类，数量和分布等因素对涂层高温腐蚀行为的影响规律及其作用机制。涂层于1100 ℃氧化200小时后的结果表明，NiAl涂层中活加的氧化物质点起到了改善Al_2O_3膜的粘附性，减缓涂层的退化等作用，显著地降低了涂层的氧化增重速率和氧化膜的剥落量。在实验范围内发现，涂层的抗氧化性能的改善与所添别的稀土化物的种类有关，添加La_2O_3，特别是Gd_2O_3质点改善涂层的抗氧化性能更为显著。涂层于850 ℃在（Na, K）_2SO_4混和熔盐中的热腐蚀实验结果表明，稀土氧化物质点可促进保护性氧化膜的形成，并通过在表面区的富集捕获S，生成了Y_2O_2S等稀土氧硫化物，减少了S向涂层内部的侵入，从而较单一的镀镍渗铝涂层具有更好的抗热腐蚀性能。在900 ℃渗铝过程中，涂层中部分细小的弥散氧化物质点的在基体／涂层界面附近形成聚集带，它极大地了涂层内侧NiAl相的退化等。本文针对氧化物质点形成聚集的机制和聚集层内氧化物的尺寸，数量，分布等对涂层退化，抗高温腐蚀性能的影响等进行了详尽的分析。化学分析，光学金相，EPMA，SEM及r-ray衍射等技术被用于涂层中元素的含量与分布，涂层显微组织，氧化膜形貌，涂层上氧化膜及盐腐蚀产物相组成等的分析检测。 |
| Other Abstract | NiAl-R_2O_3 composite coatings containing dispersed Y_2O_3e, La_2O_3 and Gd_2O_3 particles separately have been prepared with the processes of Ni-R_2O_3 co-electrodeposition and post diffusion aluminizing, and the effect of the type, amount and distribution of the particles on high temperature corrosion of the coatings and the mechanism were studied emphatically. The result of the oxidation exposed at 1100 ℃ for 200 hours showed that, the additive oxides improved the adherence of the scales, and inhibited the degradation of the coatings, thus red uced the oxidation rates of coatings and spalled masses of t he scales greatly. In the experiment, it was revealed that the improvement of oxidation resistance of the coatings was associated with the kind of the additive oxides, and additions of La2O_3, especially Gd_2O-3 were more effective. The result of hot corrosion carried out in (Na, K)2SO_4 fused salt at 850 ℃ showed, the additive oxides could promote the formation of protective scale, and their accumulation to the surface of coatings had the effect of capturing sulphur, reducing the diffusion of surphur to depth in the coatings, thus the composite coatings were murch better to resist hot corrosion than the aluminide coating on Ni-plated alloy. During aluminizing at 900 ℃, the finely dispersed particles moved to the substrate/coating interfaces partially and formed accumulated oxide layers which influenced the degradation of inner NiAl phase greatly. The paper discussed the mechanism in which the oxides accumulated, and the influence of size, a mount and distribution of the oxides in the layers on high temperature corrosion resistance in detail. Chemical analysis, optical microscope, EPMA, SEM and x-ray diffraction techniques were used to examined the content and distribution of scales, and phases composition of the coatings, coatings, scales and hot corrosi on products. |
| Pages | 70 |
| Language | 中文 |
| Document Type | 学位论文 |
| Identifier | http://ir.imr.ac.cn/handle/321006/17440 |
| Collection | 中国科学院金属研究所 |
| Recommended Citation GB/T 7714 | 马信清. 弥散稀土氧化物改进的复合铝化物涂层抗高温氧化行为的研究[D]. 中国科学院金属腐蚀与防护研究所. 中国科学院金属腐蚀与防护研究所,1990. |
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