结晶器铜板等离子喷涂镍-石墨涂层的耐磨性

Wear resistance of plasma sprayed Nickel-Graphite coating on continuous casting copper mold

为提高连铸结晶器铜板的使用寿命和铸坯质量,采用超音速等离子喷涂技术在结晶器铜板材料Cr-Zr-Cu基体上制备镍-石墨自润滑涂层,利用扫描电镜(SEM)对喷涂粉末和涂层的组织形貌进行表征,通过球-盘式摩擦磨损实验研究载荷和温度对镍-石墨自润滑涂层、摩擦系数、磨损量的影响,并对涂层的磨损机制进行分析.结果表明:利用超音速等离子喷涂制备的镍-石墨涂层与基体结合良好,结构致密;涂层的摩擦系数和磨损量均随着载荷的增加而增加,不同载荷下涂层的磨损机制均是磨粒磨损,且随着载荷增加,磨粒磨损加剧;涂层的摩擦系数随着温度的增加而增加,且磨损机制均为氧化磨损,但是温度为225℃时,以石墨的润滑作用为主,温度为425℃时,石墨相被氧化镍覆盖,石墨的润滑作用降低,以氧化镍的润滑作用为主.镍-石墨涂层能显著降低Cr-Zr-Cu基体的摩擦系数和磨损量,提高结晶器的耐磨性能.

To improve the life of continuous casting copper moldand the quality of slab, Nickel-Graphite self-lubricating coating was prepared on Cr-Zr-Cu alloy for continuous casting mold by supersonic plasma spraying. Morphologies of the sprayed powder and the coating were characterized by Scanning Electron Microscopy(SEM). Effects of load and temperature on the friction coefficient and wear mass of Nickel-Graphite self-lubricating coating were investigated by a ball-plate type sliding wear test, and the wear mechanism of the coating was analyzed. Results show that the Nickel-Graphite coating prepared by supersonic plasma spraying possess was ingood bonding statewith high density. The wear testing result suggestthat the friction coefficient and the wear massincreased with the increaseof load. The wear mechanism of the coating under different loadswas abrasive wear, and the wear of the abrasive became worse with increasing load. The friction coefficient of the coating increased with increasing temperature, and the wear mechanism was oxidative wear. However, when the temperature was 225 ℃, the lubricating effect of graphite was dominant. When the temperature was 425 ℃, the graphite phase was covered by nickel oxide, the lubrication of the graphitewas reduced, and the nickel oxide acted as a lubricant. The Nickel-Graphite coating can significantly reduce the friction coefficient and wear mass of the Cr-Zr-Cu matrix, and improve the wear resistance of the mold.