矿用截齿是矿井开采损坏率最大的零件，在大冲击、高磨损的严苛工况，截齿的损坏现象尤为严重，失效截齿将直接影响整个采掘作业的效率和生产进程。随着激光熔覆技术的迅速发展，制备具有优异耐磨性的陶瓷相增强金属基耐磨层成为可能，在矿用截齿表面强化防护和修复等方面具有巨大的发展前景。本文在对市售典型矿用截齿的组织和力学性能进行综合评价基础上，利用激光熔覆技术在截齿齿体表面分别制备了WC、TiC、（TiC+WC）增强Ni基熔覆层，分析了熔覆层的微观组织结构以及在三体和冲击工况下磨损特性，探究了WC及TiC含量和配比对Ni基熔覆层组织和性能的影响规律。本文获得了如下主要结论：

（1）具有高致密的硬质合金、高抗剪强度的钎焊层、恰当的热处理制度和高体积分数硬质相的防护层是提升截齿服役性能的有效手段，尤以高硬质相含量熔覆防护层对改善低冲击工况下截齿的三体磨损性能更为突出。

（2）WC增强Ni基熔覆层主要由Ni基固溶体γ、WC、W₂C和少量（Cr，Fe）₇C₃、Fe₃C、Ni₄B₃组成，WC和γ基体界面结合良好。WC在基体中分布不均匀，熔覆层上部分布较少。由于WC颗粒的熔解在基体中熔融析出细小的三元共晶组织，而且共晶组织的形态与WC添加量以及熔覆层所处部位有关。

（3）WC增强Ni基熔覆层的磨损失重和磨损机制与所处工况有关。在三体磨料磨损工况下，磨损失重随着WC含量的增加呈现降低趋势；但在冲击磨料磨损工况下，磨损失重随WC含量的增加而增加。随着WC含量的增加三体磨损机制由低硬质相下的微切削磨料磨损转变为高硬质相下的多次塑变磨损；冲击磨损机制由低硬质相下的凿削式塑变疲劳磨损转变为高硬质相的破碎剥落机制。

（4）TiC增强Ni基熔覆层主要由TiC、γ（Ni，Fe）组成，TiC、WC复合增强Ni基激光熔覆层主要由WC、W₂C、TiC、γ-Ni和少量的（Cr，Fe）₇C₃、（W,TiC）C_1-x组成，其中复合增强Ni基熔覆层中的W元素在TiC周围发生了偏聚现象，原位生成新的固溶体。

（5）TiC、WC复合增强Ni基熔覆层的复合强化进一步提升了熔覆层的显微硬度，在三体磨料磨损工况下，磨损失重随硬质相含量的增加呈降低趋势；但在冲击磨料磨损工况下，高陶瓷相提高熔覆层本征脆性，磨损失重随硬质相含量增加而增加。

Mining pick is the part with the largest damage rate in mining. Under the severe working conditions of large impact and high wear, the damage of pick is particularly serious. The failure of pick will directly affect the efficiency and production process of the whole mining operation. With the rapid development of laser cladding technology, it is possible to prepare ceramic phase reinforced metal based wear-resistant layer with excellent wear resistance. It has great development prospects in strengthening protection and repair of mining pick surface. Based on the comprehensive evaluation of the microstructure and mechanical properties of typical commercial mining pick, WC, TiC and (TiC + WC) reinforced Ni based cladding layers were prepared on the surface of pick by laser cladding technology. The microstructure and wear characteristics of the cladding layer under three body and impact conditions were analyzed, and the effects of WC and TiC content and ratio on the microstructure and properties of Ni based cladding layer were explored. The main conclusions of this paper are as follows:

（1）High density cemented carbide, brazing layer with high shear strength, appropriate heat treatment system and protective layer with high volume fraction of hard phase are effective means to improve the service performance of the pick, especially the cladding protective layer with high content of hard phase is more prominent to improve the three body wear performance of the pick under low impact conditions.

（2）WC reinforced Ni based cladding layer is mainly composed of Ni based solid solution γ、 WC, W₂C and a small amount of (Cr, Fe)₇C₃, Fe₃C and Ni₄B₃, the interface between WC and γ-matrix is well bonded. WC is unevenly distributed in the matrix and less distributed in the upper part of the cladding layer. Due to the melting of WC particles, fine ternary eutectic structure is melted and precipitated in the matrix, and the morphology of eutectic structure is related to the amount of WC and the position of cladding layer.

（3）The wear weight loss and wear mechanism of WC particle reinforced Ni based cladding layer are related to the working conditions. Under the condition of three body abrasive wear, the wear weight loss decreases with the increase of WC content; However, under the condition of impact abrasive wear, the wear weight loss increases with the increase of WC content. With the increase of WC content, the three body wear mechanism changes from micro cutting abrasive wear in low hard phase to multiple plastic wear in high hard phase; The impact wear mechanism changes from chiseling plastic deformation fatigue wear under low hard phase to crushing and spalling mechanism of high hard phase.

（4）TiC reinforced Ni based cladding layer is mainly composed of TiC, γ (Ni, Fe). TiC and WC composite reinforced Ni based laser cladding layer is mainly composed of WC, W₂C, TiC, γ - Ni and a small amount of (Cr, Fe)₇C₃, (W, TiC)C_1-x composition. The W element in the composite reinforced Ni based cladding layer is biased around TiC and forms a new solid solution in situ.

（5）The composite strengthening of TiC and WC composite reinforced Ni based cladding layer further improved the microhardness of the cladding layer. Under the condition of three body abrasive wear, the wear weight loss decreases with the increase of hard phase content; However, under the condition of impact abrasive wear, the high ceramic phase improved the intrinsic brittleness of the cladding layer, and the wear weight loss increases with the increase of the content of hard phase.

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