【摘要】：鈷基高溫合金涂層具有良好的抗氧化性能,在服役過程中表現(xiàn)出較好的涂層粘結(jié)性能,對涂層的壽命延長具有積極的作用。目前,CoCrAlTaY高溫合金粉末中存在嚴(yán)重的Ta偏聚問題。從而導(dǎo)致涂層中也存在Ta偏聚,降低了涂層的抗高溫氧化性能,嚴(yán)重影響了涂層的使用壽命。本文主要對真空霧化設(shè)備所涉及的相關(guān)工藝參數(shù)進(jìn)行了優(yōu)化,采用真空霧化法自制CoCrAlTaY高溫合金粉末,并以其為粘結(jié)層制備熱障涂層,最后對CoCrAlTaY高溫合金粉末相關(guān)特性和涂層的抗高溫氧化性能進(jìn)行了初步分析研究。具體研究內(nèi)容與結(jié)果如下：為了制備高質(zhì)量的粉末,對實驗所采用的熔煉溫度、霧化溫度、霧化壓力、導(dǎo)流管直徑等相關(guān)工藝參數(shù)進(jìn)行了優(yōu)化。同時,為了避免粉末中出現(xiàn)Ta的偏聚,實驗采用CoTa中間合金作為Ta的原料制備CoCrAlTaY高溫合金粉末,并對粉末相關(guān)特性進(jìn)行研究,結(jié)果表明：采用CoTa合金代替Ta為原料制備的粉末,其微觀組織較為均勻,白色塊狀物質(zhì)幾乎消失,但微區(qū)內(nèi)仍存在絮狀Ta；粉末中主要存在γ'、Cr23C6和TaC相,其中Ta主要以TaC和CoTa3的形式存在,其余彌散分布于整個粉末顆粒中。以自制粉末為粘結(jié)層制備熱障涂層,初步研究溫度與氧化方式、水蒸氣環(huán)境以及粘結(jié)層成分等因素對熱障涂層試樣的抗高溫氧化性能和壽命的影響。結(jié)果表明：相比于1050℃,試樣于1000℃下的熱障涂層壽命更長,這可能是由于增加的50℃促進(jìn)了熱氧化物(TGO)的生長和元素間的互擴(kuò)散所致；由于在循環(huán)氧化條件下產(chǎn)生會應(yīng)力,因此相比持續(xù)氧化,經(jīng)循環(huán)氧化后熱障涂層試樣的壽命縮短了近二分之一；在高氧分壓水蒸氣環(huán)境中,裂縫的生長和擴(kuò)散更為快速、簡單,熱障涂層的使用壽命更短；由于Co基粘結(jié)層具有較低的熱膨脹系數(shù),因此相比1050℃的溫度循環(huán)條件下,自制CoCrAlTaY高溫合金粉末為粘結(jié)層的熱障涂層試樣,經(jīng)1100℃循環(huán)氧化后,其使用壽命比含有富Ni相的NiCoCrAlTaY粘結(jié)層更長。
[Abstract]:Co-based superalloy coating has good oxidation resistance and good adhesion during service, which has a positive effect on prolonging the life of the coating. At present, there is a serious problem of Ta segregation in CoCrAlTaY superalloy powder. As a result, Ta segregation also exists in the coating, which reduces the oxidation resistance of the coating at high temperature and seriously affects the service life of the coating. In this paper, the related technological parameters of vacuum atomization equipment were optimized. CoCrAlTaY superalloy powder was prepared by vacuum atomization method and used as adhesive layer to prepare thermal barrier coating. Finally, the properties of CoCrAlTaY superalloy powder and the oxidation resistance of the coating were studied. The main contents and results are as follows: in order to prepare high quality powder, the process parameters such as melting temperature, atomization pressure, pipe diameter and so on were optimized. At the same time, in order to avoid the segregation of Ta in the powder, the CoTa master alloy was used as the raw material of Ta to prepare the CoCrAlTaY superalloy powder, and the related properties of the powder were studied. The results showed that the powder prepared by using CoTa alloy instead of Ta as raw material, The microstructure was uniform, the white mass almost disappeared, but the flocculent Ta; still existed in the microzone. There are mainly 緯', Cr23C6 and TaC phases in the powder, in which Ta exists mainly in the form of TaC and CoTa3, and the other dispersions are distributed in the whole powder particles. Thermal barrier coatings were prepared by using self-made powder as bonding layer. The effects of temperature, oxidation mode, water vapor environment and composition of bonding layer on the oxidation resistance and life of thermal barrier coatings were studied. The results show that the lifetime of thermal barrier coating at 1000 鈩，

本文編號：2383348