Microstructure and wear resistance of TiB₂-TiC/Fe composite coatings on Q235 steel prepared by plasma cladding

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 and α-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 (35wt%) 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 30wt% 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.