探討不同製程之碳化矽複合材料於高溫離子輻照環境下之空孔形成

Effect of ion irradiation on void formation in different processed SiC/SiCf composites under high temperature environments

邱奕哲(I-Che Chiu)

指導教授 ： 開執中

國立清華大學/原子科學院/工程與系統科學系/碩士(2013年)

摘要

碳化矽複合材料是目前公認最具有潛力之核能結構材料，擁有核能結構材料所需之條件，低活性、耐輻照、高溫機械性質佳、抗腐蝕等優點。
本論文主要研究全纖維碳化矽複合材料SA-Tyrannohex於高溫矽離子與氦離子輻照下之微結構變化，並與其他核能級碳化矽複合材料之空孔形成做一比較。本實驗利用清華大學加速器館之9SDH串級式加速器以及高能離子佈植機分別進行佈植，分析條件為Si2+,5 dpa~150 dpa分別於1350℃，1500℃以及He+,15000 appm於1300℃、1500℃。
從單射束矽離子輻照結果可知，於1350℃以及1500℃環境下，纖維中都明顯有圓形小空孔析出，空孔直徑約2 nm，並不隨劑量上升而顯著成長，空孔密度隨著劑量上升至約1024 #/m3，並與Hi-Nicalon Type-S複合材料、Tyranno-SA複合材料以及CVD多晶碳化矽比較可知，由於本材料所使用之纖維晶粒約300 nm，較複合材料「基材」部分以及多晶碳化矽晶粒小，所以晶界面積較大，較不易造成空缺聚集形成空孔，顯示有較佳之抗空孔能力。
單射束氦離子輻照方面，也由於晶界面積關係，所以氦離子無法有效堆積形成氦氣泡，顯示SA-Tyrannohex全纖維碳化矽複合材料，對於氦離子單射束輻照有極佳之抗氦氣泡之能力。

關鍵字

碳化矽複合材料 ； 離子輻照 ； 空孔

並列摘要

Silicon carbide composites are considered as the plasma facing material in fusion reactors. Therefore, high dose neutron irradiation and helium accumulation due to emission of alpha-particles from (n,α) nuclear reaction in fusion reactor are significant issues in mechanical property. This thesis will focus on the effect of ion irradiation on void formation in different processed SiC/SiCf composites under high temperature environments.
In this study, The novel SiC composite – SA-Tyrannohex SiC fiber-bonded composite was irradiated by 5.1 MeV-Si2+ and 300 keV-He+ at 1300℃ to 1500℃, respectively. The dose was up to 150 dpa and the helium accumulation concentration was 15000 appm. The microstructure evolution of irradiated SiC was examined by transmission electron microscopy.
The average diameter of cavities induced by Si2+ irradiation increased both with the increasing temperature and irradiation damage, up to 2.5 nm at 150 dpa/1500℃. However, the number density of cavity was almost saturated at 50 dpa. No helium bubble was abserved in the 15000 appm irradiated sample at 1300℃ and 1500℃.
Comparison to Hi-Nicalon Type-S compsite、Tyranno-SA composite and CVD polycrystalline SiC, SA-Tyrannohex fiber-bonded composite appears to has excellent resistance to cavity formation due to small grain size during Si2+ and He+ irradiation at high temperatures.

並列關鍵字

SiC composites ； ion irradiation ； void

參考文獻

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