Liu Guiliang, Li Yipeng, He Zongbei, Chen Yang, Cong Shuo, Chen Zhaoke, Huang Xiuyin, Zhang Ruiqian, Ran Guang
State Key Laboratory for Nuclear Fuel and Materials, Nuclear Power Institute of China, Chengdu 610213, China.
College of Energy, Xiamen University, Xiamen 361102, China.
Materials (Basel). 2020 Dec 6;13(23):5567. doi: 10.3390/ma13235567.
The microstructure and nanoindentation hardness of unirradiated, irradiated, annealed and corroded SiC coatings were characterized. Irradiation of 400 keV C and 200 keV He with approximately 10 dpa did not cause obvious amorphous transformation to nanocrystal SiC coatings and induced helium bubbles with 2-3 nm dimension distributed uniformly in the SiC matrix. High temperature annealing resulted in the transformation of SiC nanocrystals into columnar crystals in the irradiated region. Line-shaped bubble bands formed at the columnar crystal boundaries and their stacking fault planes and made the formation of microcracks of hundreds of nanometers in length. Meanwhile, some isolated helium bubbles distributed in SiC grains still maintained a size of 2-3 nm, despite annealing at 1200 °C for 5 h. The SiC coating showed excellent corrosion resistance under high-temperature, high-pressure water. The weight of the sample decreased with the increase of corrosion time. The nanoindentation hardness and the elastic modulus increased significantly with C and He irradiation, while their values decreased with high-temperature annealing. An increase in the annealing temperature led to an increased reduction in the values. Corrosion caused the decrease of nanoindentation hardness and the elastic modulus in the whole test depth range, whether the samples were irradiated or unirradiated.
对未辐照、辐照、退火和腐蚀后的碳化硅涂层的微观结构和纳米压痕硬度进行了表征。用400 keV的碳离子和200 keV的氦离子进行辐照，剂量约为10 dpa，未使纳米晶碳化硅涂层发生明显的非晶化转变，而是在碳化硅基体中诱导产生了尺寸为2-3 nm的均匀分布的氦泡。高温退火导致辐照区域内的碳化硅纳米晶体转变为柱状晶体。在柱状晶体边界及其堆垛层错平面上形成了线状气泡带，并导致了长度达数百纳米的微裂纹的形成。同时，尽管在1200℃下退火5小时，一些分布在碳化硅晶粒中的孤立氦泡尺寸仍保持在2-3 nm。碳化硅涂层在高温高压水中表现出优异的耐腐蚀性。样品的重量随腐蚀时间的增加而降低。纳米压痕硬度和弹性模量随碳离子和氦离子辐照显著增加，而随高温退火降低。退火温度升高导致其值的降低幅度增大。腐蚀导致纳米压痕硬度和弹性模量在整个测试深度范围内降低，无论样品是否经过辐照。
