本文選題：Si改性鋁化物涂層 + CVD�。� 參考：《機械科學(xué)研究總院》2015年碩士論文

【摘要】：航空發(fā)動機渦輪葉片通常采用化學(xué)氣相沉積(CVD)法在內(nèi)腔和外表面涂覆一層單一鋁化物涂層,以降低葉片的高溫腐蝕。但這種鋁化物涂層抗熱腐蝕性能較差,長期在高溫中服役時,涂層會與基體合金元素會發(fā)生互擴散,造成涂層中鋁含量降低,最終導(dǎo)致涂層表面不能形成連續(xù)致密的氧化鋁保護膜,涂層即失去保護作用。通過向單一鋁化物涂層中加入改性元素形成改性鋁化物擴散障涂層,可明顯提高涂層的抗高溫氧化性能和抗熱腐蝕性能,進而提高航空發(fā)動機渦輪葉片的使用壽命。本文使用CVD法沉積+擴散復(fù)合處理工藝對前期試驗制備的單一鋁化物涂層進行了優(yōu)化,處理后涂層中的元素擴散得較為充分,涂層組織均勻,同時,涂層厚度會有一定程度的增加,內(nèi)層占涂層厚度比例發(fā)生變化,涂層呈現(xiàn)不同的結(jié)構(gòu)。通過鋁化物沉積+擴散復(fù)合處理工藝前后涂層成分、組織結(jié)構(gòu)變化,本文對CVD法沉積+擴散復(fù)合處理工藝下單一鋁化物涂層形成過程進行了研究。在對CVD法單一鋁化物涂層制備工藝和形成過程深入認識的基礎(chǔ)上,本文系統(tǒng)地研究了CVD法Si改性鋁化物涂層制備工藝,發(fā)現(xiàn)一步Al-Si共沉積工藝可控性差,涂層中元素出現(xiàn)相間分布的特殊情況;兩步法中先沉積Al后沉積Si會導(dǎo)致硅化物替代鋁化物的情況發(fā)生;先沉積Si后沉積Al可較容易地制備出外層富Al內(nèi)層富Si的雙層結(jié)構(gòu)涂層,外層與內(nèi)層通過冶金結(jié)合,涂層結(jié)構(gòu)合理。因此,選擇CVD法先沉積Si后沉積Al工藝制備硅改性鋁化物涂層,進而研究采用CVD法先沉積Si后沉積Al+擴散復(fù)合處理工藝,與無擴散處理的硅改性鋁化物涂層相比,涂層厚度增加,在外層與內(nèi)層之間出現(xiàn)富Al的中間層,涂層成分分布、組織更為均勻。本文進行了1100℃溫度下60h的高溫氧化試驗,結(jié)果表明Si改性鋁化物復(fù)合涂層表現(xiàn)出比單一鋁化物涂層更為優(yōu)異的抗高溫氧化性能。在高溫氧化過程中單一鋁化物涂層中的Al含量降低;Si改性鋁化物復(fù)合涂層中Si對Al的內(nèi)擴散起到了很好的阻擋作用。在高溫氧化過程中,Si改性鋁化物涂覆試樣和單一鋁化物涂覆試樣都先后經(jīng)歷增重較快的氧化初期階段(0~20h)和增重較慢的氧化平穩(wěn)階段(20~60h)。
[Abstract]:In order to reduce the high temperature corrosion of aero-engine turbine blades, chemical vapor deposition (CVD) method is usually used to coat the inner and outer surfaces with a single aluminized coating. However, the thermal corrosion resistance of the aluminized coating is poor. When the coating is in service at high temperature for a long time, the coating will interdiffusion with the alloy elements of the substrate, resulting in the decrease of the aluminum content in the coating. Finally, the coating surface can not form a continuous dense aluminum oxide protective film, the coating will lose its protective effect. By adding the modified elements into the single aluminized coating to form the modified aluminum diffusion barrier coating, the high temperature oxidation resistance and thermal corrosion resistance of the coating can be improved obviously, and the service life of the aero-engine turbine blade can be improved. In this paper, the single aluminized coating was optimized by CVD deposition and diffusion process. After the treatment, the elements in the coating were diffused more fully, the structure of the coating was uniform, and the structure of the coating was uniform, at the same time, The coating thickness will increase to a certain extent, the ratio of inner layer to coating thickness will change, and the coating presents different structure. In this paper, the formation process of single aluminized coating under CVD deposition and diffusion composite treatment was studied by changing the composition and structure of the coating before and after the deposition and diffusion composite treatment of aluminides. Based on the deep understanding of the preparation process and formation process of single aluminum oxide coating by CVD method, the preparation process of Si modified aluminum oxide coating by CVD method is systematically studied. It is found that the one-step Al-Si co-deposition process is not controllable. In the two-step method, the deposition of Al and then the deposition of Si will lead to the occurrence of silicides instead of aluminides. It is easy to prepare Si-rich bilayer structure coatings with Al-rich inner layer by deposition of Al and then Al. The structure of the coating is reasonable by metallurgical bonding of outer layer and inner layer. Therefore, Si-modified aluminized coating was prepared by CVD method and then deposited by Al process, and then the CVD method was used to deposit Si and then deposited Al diffusion composite coating, which was compared with the silicon-modified aluminized coating without diffusion treatment. With the increase of coating thickness, there is an Al rich interlayer between the outer layer and the inner layer, the composition of the coating is distributed and the microstructure is more uniform. The high temperature oxidation test at 1100 鈩，

本文編號：1847560