【摘要】 采用3kW高功率半导体激光器,在45钢基体上制备不同WC含量(质量分数20%~80%)的WC-NiSiB复合涂层,用扫描电镜(SEM)、能谱仪(EDS)及X射线衍射(XRD)对熔覆层的微观组织、成分分布及物相进行表征,并测试涂层试样的硬度与耐磨性能。结果表明,激光熔覆WC-NiSiB复合涂层组织主要由γ-Ni、WC、W2C、WB、W2B、Ni4B3及Ni4W等物相组成,熔覆层与基体形成冶金结合。涂层与基体的结合区,从熔合线开始逐渐向上的组织依次为垂直于界面的胞状晶、柱状晶和枝状晶,熔覆层中部为沿一定方向生长的树枝晶,表层为异向生长的细小树枝晶。随WC颗粒含量增加,涂层中WC颗粒分布更加密集。WC含量为60%时,WC颗粒分布均匀致密,熔覆层无裂纹,熔覆层的硬度最高达到1291HV,为NiSiB合金层硬度的2.7倍,耐磨性是NiSiB合金层的6.8倍。更多还原

【Abstract】 WC-NiSiB composite coatings with different WC contents were prepared on 45 steel substrate using 3k W high power diode laser. The morphology, composition and phase transformation of laser cladding layer were studied by scanning electronic microscope(SEM), energy dispersive spectroscopy(EDS), and X-ray diffraction(XRD), respectively.The results show that the phase compositions of diode laser cladding WC-NiSiB alloy are γ-Ni、WC、W2C WB、W2B、Ni4B3、Ni4W, etc; the cladding layer has a metallurgical bonding with substrate; the morphology of crystal grain at the bottom of lading layer is cell structure, whose growth is perpendicular to the interface of cladding and substrate; then the columnar grain transits to dendrite structure; the morphology of crystal grain at the central and top zones of layer is dendritic structure and grows with a single direction, but the crystal grain at surface layer grows with random direction;with the increase of WC particle content, distribution of WC in the coating is more intensive. When WC content is 60%,WC particle distribute uniformly and there is no crack in the layer. The highest hardness of HV 1217 in cladding layer is2.7 times of NiSiB coating and it’s wear resistance is 6.8 times of NiSiB coating.更多还原