锆合金热挤压用防护润滑剂的试制与性能

Trial manufacture and properties of protective lubricants for hot extrusion of zirconium alloy

  • 摘要: 为满足锆合金热挤压时的润滑与防护需求,试制了一种锆合金热挤压用防护润滑剂,主要成分包括有机硅树脂、低软化点玻璃粉、氧化铝粉、二硫化钼、石墨粉、滑石粉、云母粉等。实验温度为700~800 ℃时,采用圆环压缩法测得涂覆有润滑剂的Zr-4合金摩擦因子为0.19~0.25,润滑效果良好。将有润滑剂防护的锆合金分别加热至700、800和900 ℃并保温1 h,未发生明显氧化,热防护性能良好。测定了有、无润滑剂条件下Zr-4合金和H13模具钢的界面接触温度随接触时间的变化曲线。当Zr-4合金和H13钢的初始界面温度分别约为700 ℃和350 ℃时,无润滑剂时Zr-4合金表面温度达到稳定的时间为7.7 s,界面换热系数由250 W·m−2·℃−1增大至2700 W·m−2·℃−1;有润滑剂时Zr-4合金表面温度达到稳定的时间延长至12 s,界面换热系数由131 W·m−2·℃−1增大至1900 W·m−2·℃−1。这表明该润滑剂具有较好的高温热障性能。

     

    Abstract: Lubrication is the key in obtaining excellent products when zirconium alloys are hot extruded. Reasonable lubrication conditions are important to improve the product quality, reduce energy consumption, and prolong the service life of tools and dies. Presently, the glass lubricants commonly used in domestic industry are not very suitable for hot extrusion zirconium alloy, and they still need to be imported. In order to meet the requirements of lubrication and protection during hot extrusion of zirconium alloy, a protective lubricant for hot extrusion of zirconium alloy was trial manufactured in this paper. The main components of this protective lubricant include silicone resin, low softening point glass powder, aluminum oxide (Al2O3) powder, molybdenum disulfide, graphite powder, talcum powder, mica powder, and others. When the experimental temperature is in the range of 700−800 ℃, the friction factor of Zr-4 alloy coated with the lubricant is calculated to be 0.19−0.25 by the ring compression method, which shows good lubrication effect. The zirconium alloy with lubricant protection is not obviously oxidized after heating at 700 ℃, 800 ℃, and 900 ℃, respectively, for 1 h, indicating that the lubricant has good thermal protection effect. The relation curves between contact temperature and time at the interface of the Zr-4 alloy and H13 die steel are measured. The initial interface temperatures of the Zr-4 alloy and H13 steel are 700 ℃ and 350 ℃, respectively. Without the lubricant, the time for the surface temperature of the Zr-4 alloy to reach stability is 7.7 s, and the interfacial heat transfer coefficient increases from 250 W·m−2·℃−1 to 2700 W·m−2·℃−1. On the other and, when the lubricant was used, the time for the surface temperature of Zr-4 alloy to reach stability is prolonged to 12 s, and the interfacial heat transfer coefficient increases from 131 W·m−2·℃−1 to 1900 W·m−2·℃−1, indicating that the lubricant has good thermal barrier properties.

     

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