Date Published: April 6, 2017
Publisher: Public Library of Science
Author(s): Yan-Ping Wu, Zheng-Yang Li, Sheng-Fa Zhu, Lei Lu, Zhen-Bing Cai, Jie Zheng.
The Ti/TiN multi-layer film was prepared on the depleted uranium (DU) substrate by cathodic arc ion plating equipment. The character of multi-layer film was studied by SEM, XRD and AES, revealed that the surface was composed of small compact particle and the cross-section had a multi-layer structure. The fretting wear performance under different frequencies was performed by a MFT-6000 machine with a ball-on-plate configuration. The wear morphology was analyzed by white light interferometer, OM and SEM with an EDX. The result shows the Ti/TiN multi-layer film could greatly improve the fretting wear performance compared to the DU substrate. The fretting wear running and damaged behavior are strongly dependent on the film and test frequency. The fretting region of DU substrate and Ti/TiN multi-layer under low test frequency is gross slip. With the increase of test frequency, the fretting region of Ti/TiN multi-layer change from gross slip to mixed fretting, then to partial slip.
Three isotopes of uranium exist in the natural world, 238U, 235U, 234U, in the relative content of 99.275, 0.720, and 0.005%, respectively . DU is produced as a nuclear waste in the uranium enrichment process, so the 235U content of DU was about 0.2–0.4% less than natural uranium. Thus it has less radio-active and usually used as DU ammunition and DU-armored tanks due to the greatly performance of armor-piercing strength . However, the DU has a high chemical reactivity. When the DU is exposed to salty, humid and high temperature condition, it is easy to corrode. Hence, Al-based coating [3–5], Ti-based coating [4–6], Cr-based coatings [7, 8] and adding alloy element such as niobium , has been applied to enhance corrosion resistance of uranium.
The Ti/TiN multi-layer film was prepared on the DU substrate, the character of multi-layer film was conduct by SEM, XRD and AES, revealed that the Ti/TiN multi-layer surface was composed of many small particles and compact. The fretting wear performance was performed under different frequencies. The observation and analysis led to the following conclusions: