Acta Phys. -Chim. Sin. ›› 2015, Vol. 31 ›› Issue (Suppl): 111-116.doi: 10.3866/PKU.WHXB2014Ac04

• ARTICLE • Previous Articles    

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

CHEN Zhi-Lei, ZHANG Yong-Bin, HU Yin, LUO Li-Zhu, LIU Ke-Zhao   

  1. Science and Technology on Surface Physics and Chemistry Laboratory, P. O. Box 718-35, Mianyang 621907, Sichuan Province, P. R. China
  • Published:2015-05-20
  • Contact: LIU Ke-Zhao E-mail:liukz@hotmail.com
  • Supported by:

    The project was supported by the Special Fund of China Academy of Engineering Physics (90907-0703).

Abstract:

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 Xray 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.

Key words: Pulsed laser, Nitriding, Uranium, Surface morphology, Crack, Corrosion resistance

MSC2000: 

  • O641