【摘要】：目的采用低溫超音速等離子噴涂(LT-HVOF)在鎳基高溫合金基體(K417)上制備了NiCoCrAlYTa粘結(jié)層,使用大氣等離子噴涂(APS)在粘結(jié)層上制備了納米7%Y_2O_3-ZrO_2(7YSZ)陶瓷涂層,以獲得溫度梯度熱循環(huán)下納米陶瓷層的結(jié)構(gòu)演變機制。方法通過燃?xì)鉄釠_擊實驗儀對熱障涂層模擬真實服役條件下溫度梯度熱循環(huán)的工作環(huán)境,采用一維穩(wěn)態(tài)熱傳導(dǎo)模型計算了熱障涂層中各涂層界面的溫度,探討了在熱驅(qū)動作用下等徑晶粒和非等徑晶粒的擴(kuò)散長大機制。結(jié)果熱循環(huán)次數(shù)為40次時,涂層近表面出現(xiàn)了燒結(jié)致密化現(xiàn)象,而陶瓷層底部涂層保持原來的結(jié)構(gòu)。熱循環(huán)次數(shù)增加到460次時,整個陶瓷層斷面都發(fā)生了燒結(jié)致密化現(xiàn)象。結(jié)論溫度是涂層燒結(jié)致密化的主導(dǎo)因素。涂層中當(dāng)?shù)却缶Я＝佑|形成彎曲頸時,由于彎曲頸只受水平方向靜壓力作用,晶粒中原子擴(kuò)散速率慢,導(dǎo)致晶粒長大速率較慢;而當(dāng)非等大晶粒接觸形成彎曲頸時,在晶粒接觸彎曲頸處存在一偏大晶粒方向的剪切力,其導(dǎo)致晶粒向彎曲頸擴(kuò)散速率增加,晶粒長大速率較快。
[Abstract]:Objective to prepare NiCoCrAlYTa adhesive layer on nickel base superalloy matrix (K417) by low temperature supersonic plasma spraying (LT-HVOF). Nano-7%Y_2O_3-ZrO_2 (7YSZ) ceramic coating was prepared by atmospheric plasma spraying (APS) on the bonding layer to obtain the structural evolution mechanism of the nano-ceramic layer under temperature gradient thermal cycle. Methods the working environment of temperature gradient thermal cycle of thermal barrier coating was simulated by gas thermal shock tester, and the interface temperature of each coating in thermal barrier coating was calculated by using one-dimensional steady-state heat conduction model. The diffusion growth mechanism of equal diameter grain and non equal diameter grain under thermal drive is discussed. Results when the number of thermal cycles was 40 times, the sintering densification appeared near the surface of the coating, while the coating at the bottom of the ceramic layer maintained the original structure. When the number of thermal cycles increases to 460, sintering densification occurs in the whole ceramic layer section. Conclusion temperature is the main factor of sintering densification of coating. When the curved neck is formed by equal grain contact, the diffusion rate of atoms in the grain is slow because the curved neck is only affected by the horizontal static pressure, which leads to the slow grain growth rate. When the bending neck is formed by non-equal grain contact, there is a shear force in the direction of large grain at the grain contact bending neck, which leads to the increase of grain diffusion rate to the bending neck and the faster grain growth rate.
【作者單位】： 廣東省新材料研究所;現(xiàn)代材料表面工程技術(shù)國家工程實驗室;華南理工大學(xué)材料科學(xué)與工程學(xué)院;
【基金】：國家“973”計劃(2012CB625100)~~
【分類號】：TG174.453

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