【摘要】：隨著中溫SOFC技術(shù)的成熟應(yīng)用,使得低價不銹鋼鐵素體作為連接體成為可能。但是,在SOFC的工作環(huán)境中,不銹鋼鐵素體表面會不斷發(fā)生氧化,鐵素體中會不斷揮發(fā)出氣態(tài)Cr,從而導致面比電阻增大與單電池的陰極毒化。在基體的表面增加一層抗高溫氧化且導電的涂層是解決這些問題的一種有效辦法。最近,一些尖晶石涂層,尤其是(Cu,Mn)_3O_4因其具有較高的電導率、與不銹鋼鐵素體匹配的熱膨脹系數(shù)(TCE)以及良好的抑制Cr向外揮發(fā)的能力而受到了科學家們的重點關(guān)注。本文首先用電沉積的方法以氯酸鹽體系、用EDTANa_2作為絡(luò)合劑在430SS不銹鋼鐵素體表面制備了 Cu-Mn合金鍍層,利用SEM及EDS研究鍍層微觀形貌及成分變化。研究了電流密度、pH值、沉積時間、電解液中n(Cu):n(Mn)的比等參數(shù)對合金鍍層微觀結(jié)構(gòu)和成分的影響。然后,通過預氧化,即先后在750℃的氬氣和800℃的空氣中分別進行熱處理2h,從而得到銅錳尖晶石涂層。最后,研究銅錳尖晶石涂層在SOFC陰極環(huán)境下800℃空氣中和800℃空氣+10%H_2O空氣中的高溫氧化行為,并用SEM、EDS和XRD分析等手段表征氧化膜的相結(jié)構(gòu)、表面和截面微觀形貌及元素分布,研究了不銹鋼鐵素體表面沉積銅錳尖晶石涂層的氧化機制。此外,利用四點法測試銅錳尖晶石涂層高溫氧化后的面比電阻(ASR)。得出的主要結(jié)論如下:通過電沉積的方法成功的在430SS表面得到了 Cu-Mn合金鍍層,電流密度為200～700mA/cm~2、pH 值為 3～7、時間為 10～30min 和 n(Cu):n(Mn)的比為 1:20～1:10 時,鍍層中的Mn含量隨著電流密度、pH值、時間的增大而增大,隨著n(Cu):n(Mn)的比值增大而減小。當 pH=5,時間 t=20min,n(Cu):n(Mn)=1:10,電流密度 i=450、500、550mA/cm~2時,可以得到均勻、致密、無邊緣效應(yīng)、與基體結(jié)合良好、Mn含量較高且銅錳比分別為1:2、1:1、2:1的銅錳合金鍍層。預氧化處理可以使得銅錳合金完全轉(zhuǎn)變?yōu)殂~錳尖晶石涂層。氧化涂層分為兩層結(jié)構(gòu),外層為(Cu,Mn)_3O_4和內(nèi)層的富Cr氧化層組成。涂層和基體在800℃空氣中氧化300h后都具有較低的氧化速率。涂層與基體結(jié)合良好,可以降低基體在800℃的氧化速率。在含10%H_2O的空氣氧化過程中,430SS在一段時間的孕育期后發(fā)生失穩(wěn)氧化,然而(Cu,Mn)304能很好的阻止失穩(wěn)氧化的發(fā)生。在空氣和潮濕的空氣中氧化后涂層依然保持雙層結(jié)構(gòu)。(Cu,Mn)_3O_4涂層和430SS在800℃的空氣氧化300h和在800℃的潮濕空氣氧化100h的接觸電阻都隨測試溫度的升高而降低。銅錳尖晶石涂層中銅錳原子比為1:1、1:2、2:1三種尖晶石涂層在800℃空氣中氧化300h后的ASR分別為23.2mQ.cm~2、15.3mΩ·cm~2、35.3mΩ·cm~2,低于同樣條件下的基體的ASR值41mΩ·cm~2。銅錳尖晶石涂層中銅錳比為1:1、1:2、2:1三種尖晶石涂層在在800℃潮濕空氣中氧化100h后的ASR分別為33.2mQ.cm~2、25.6mQ.cm~2、69.3mQ.cm~2,也同樣低于相同條件下的基體的ASR值83mQ.cm~2。
[Abstract]:With the mature application of medium temperature SOFC technology, it is possible to use low-price stainless steel ferrite as connectors. However, in the working environment of SOFC, the surface of the stainless steel ferrite will be oxidized continuously, and the gaseous Cr will be volatilized in the ferrite, which will lead to the increase of the surface specific resistance and the cathodic toxicity of the single cell. It is an effective way to solve these problems by adding a layer of high temperature oxidation resistant and conductive coating on the surface of the substrate. Recently, some spinel coatings, especially (Cu-Mn) _ 3O _ S _ 4, have attracted great attention due to their high conductivity, thermal expansion coefficient (TCE) matching with stainless steel ferrite, and good ability to inhibit Cr outward volatilization. In this paper, Cu-Mn alloy coatings were prepared on the ferrite surface of 430SS stainless steel by electrodeposition with chlorate system and EDTANa_2 as complexing agent. The microstructure and composition of the coating were studied by SEM and EDS. The effects of current density pH value, deposition time and the ratio of n (Cu) to n (Mn) in electrolyte on the microstructure and composition of alloy coating were studied. Then, the copper manganese spinel coating was obtained by preoxidation, which was heat treated in argon at 750 鈩，

本文編號：2143198