Q235低碳钢表面等离子熔覆TiB_2-TiC/Fe复合涂层及耐磨性

Microstructure and wear resistance of TiB_2-TiC/Fe composite coatings on Q235 steel prepared by plasma cladding

采用等离子熔覆技术,以Fe55、Ti、B_4C混合粉末为原料,在Q235低碳钢表面获得了TiB_2-TiC/Fe复合涂层,并分析了涂层的物相组成、组织结构,测试了显微硬度和摩擦磨损性能,探讨了其磨损机制。TiB_2-TiC/Fe复合涂层的主要物相为TiB_2、TiC、α-Fe,其中TiB_2呈多边形和矩形,TiC则呈不规则块状;随着原始粉末中Ti、B_4C含量的增加,TiB_2、TiC尺寸逐渐增大,TiB_2-TiC/Fe涂层与基体之间结合紧密,呈冶金结合;随着TiB_2-TiC/Fe复合涂层陶瓷相含量的增加,涂层硬度和耐磨性显著提高,当陶瓷相含量增加到一定程度(35wt%)时,涂层耐磨性能有所降低,TiB_2-TiC/Fe复合涂层的磨损方式主要是磨粒磨损和剥层磨损。Ti+B_4C陶瓷相含量为30wt%的等离子熔覆涂层耐磨性能较好,约为Q235钢基体的7倍,当Ti+B_4C含量持续增加时,TiB_2、TiC尺寸增大、缺陷增多,最终使TiB_2-TiC/Fe复合涂层耐磨性降低。

TiB2-TiC/Fe composite coatings were fabricated on the surface of Q235 steel via plasma cladding by used Ti,B4C,and Fe55 as precursor materials.The phase composition,structure,microhardness and friction wear resistance of TiB2-TiC/Fe coatings were analyzed,and the wear mechanism was also discussed.The results show that the TiB2-TiC/Fe composite coatings mainly consist of TiB2,TiC andα-Fe.TiB2 phase presents rectangle or multilateral shape,and TiC phase is irregular patch shape.With the increase of ceramic content in TiB2-TiC/Fe composite coatings,the sizes of TiB2 and TiC enlarge gradually and the TiB2-TiC/Fe composite coatings are closely and metallurgically combined with Q235 steel substrate.The wear resistance and hardness of TiB2-TiC/Fe composite coatings can improve with the increasing of ceramic contents in the coatings,while the wear resistance declines when ceramic content increases to some extent（35 wt%）in TiB2-TiC/Fe composite coatings.The wear mechanism of TiB2-TiC/Fe composite coatings are mainly abrasive and delaminate wear.The plasma cladding coating with 30 wt%ceramic content has lower wearing volume,and the wear resistance of the coating is 7 times to that of Q235 steel.When the content of Ti＋B4C continues to increase,the size and defects of ceramic phase increase and the wear resistance of the coatings reduces eventually.