脉冲激光氮化改性对金属铀表面形貌的影响  

Influence on Surface Morphology of Uranium by Modification of Pulsed Laser Nitriding

作　　者：陈志磊[1] 张永彬[1] 胡殷[1] 罗丽珠[1] 刘柯钊[1] 

机构地区：[1]表面物理与化学重点实验室,绵阳市718信箱35分箱,四川绵阳621907

出　　处：《物理化学学报》2015年第B05期111-116,共6页Acta Physico-Chimica Sinica

基　　金：中国工程物理研究院专项基金（90907-0703）资助项目

摘　　要：脉冲激光氮化是一种非常有效的铀表面抗腐蚀改性方法，它与离子氮化相比具有基体升温小、改性层氮含量高、处理快速、真空室简单和精确定位等优点．而且，激光处理后样品表面犁沟、机械损伤消除，粗糙度下降．但样品表面也会出现裂纹，在腐蚀环境中，裂纹处容易发生腐蚀，降低氮化层抗腐蚀性能．因此需对激光氮化工艺进行优化，减少裂纹的产生．本文通过纳秒脉冲激光对金属铀表面进行激光氮化，并通过扫描电子显微镜（SEM）和X射线衍射（XRD）研究了激光能量密度、氮气压和激光扫描速率对氮化改性样品表面微裂纹的影响：同时，研究单点作用激光能量、脉冲重复次数对铀表面形貌的影响．结果表明：能量、气压过高，扫描速率过低引起开裂，扫描速率的影响更为显著，开裂与扫描速率以及氮化物含量有关．Pulsed laser nitriding offers several advantages such as a high nitrogen concentration, low matrix temperature, fast treatment, use of a simple vacuum chamber, and precise position control compared with ion implantation; it is an effective method for anticorrosion modification of uranium. Furrows on, and mechanical damage to, the surface are eliminated and the surface is smooth after modification. However, cracks appear on the surface during the process. In corrosive environments, the uranium is easily corroded around the cracks, and this weakens the corrosion resistance of the nitride layer. It is therefore necessary to optimize the laser nitriding process to inhibit crack formation. In this study, the uranium surface was modified using nanosecond pulsed laser nitriding.The nitride layers were characterized using scanning electron microscopy （SEM） and X- ray diffraction （XRD）. The effects on microcracks of the laser energy density, nitrogen pressure, and laser scanning speed were studied. The changes in surface morphology with changes in the laser energy and repetition time of the laser pulse interacting with the uranium surface without surface scanning were also studied. The results suggest that cracks are more likely to appear at high laser energy densities or nitrogen pressures, or low scanning speeds; the scanning speed plays a more decisive role. The appearance of cracks is related to the nitrogen concentration and the scanning speed.

关 键 词：脉冲激光 氮化 铀 表面形貌:裂纹:耐腐蚀 

分 类 号：O641[理学—物理化学]