薄带连铸结晶辊涂层研究进展

Research progress on coating of crystallization roller used for thin strip continuous casting and rolling

双辊薄带连铸结晶辊兼有铸辊和结晶器的双重作用,在连铸过程中同时受到高温磨损、热应力以及压应力的多重作用,因此,原来的辊体铜质基质材料不能满足正常的连铸需要,必须选择合适的涂层材料和工艺对其表面进行涂层处理。目前,采用电镀、化学镀、热喷涂、冷喷涂以及激光熔覆等技术手段可以在结晶辊表面制备一种或多种材料的涂层。电镀、热喷涂以及激光熔覆技术相对成熟,应用最为广泛。涂层材料有单一金属、各类合金,同时可以加入各种添加剂。选用W、Cr、Ni、Co等单质金属以及WC-Co、Cr_(2)C_(3)-Ni-Cr、Ni-Cr等合金可以获得更好的综合性能;添加Cu的合金,如WC-Cu、W-Cu、Cu-Ni等,可以获得与铜基体相近的导热系数以及膨胀系数,添加稀土元素可以细化晶粒、降低裂纹倾向。通过表面涂层处理可以大幅度提高薄带连铸结晶辊的使用寿命。

Crystallization roller used in twin-roll strip continuous casting has the dual functions of casting roll and crystallizer.In the process of continuous casting,it is simultaneously affected by high temperature wear,thermal stress and compressive stress.Therefore,the original copper matrix material of the roll body cannot meet the normal needs of continuous casting,appropriate coating materials and processes should be used for the surface coating treatment.At present,one or more materials can be used for the surface coating of crystallization rollers by means of electroplating,electroless plating,thermal spraying,cold spraying and laser cladding.Among them,electroplating,thermal spraying and laser cladding technologies are relatively mature and widely used.The coating materials included single metal,various alloys,and various additives,and comprehensive better properties could be obtained by adding different additives.Simple metals such as W,Cr,Ni,Co,and alloys such as WC-Co,Cr_(2)C_(3)-Ni-Cr and Ni-Cr.By using the alloys added with Cu,such as WC-Cu,W-Cu,Cu-Ni,can obtain thermal conductivity and expansion coefficient similar to that of copper matrix.The addition of rare earth elements can refine grains and reduce crack tendency.Through the surface coating treatment,the service life of crystallization roller can be greatly increased.