45#钢表面3D立体网状织构组织熔渗层的微观界面行为与摩擦磨损性能的研究

The wear-resistant fusing-infiltrated coating with 3D net texture will be fabricated through fusion-infiltration technology on 45# steel substrate on the basis of combination of composite materials theory and fusing-infiltrating technology. The interface between the surface fusing-infiltrated coating and substrate realized metallurgical fusion, and microstructure characteristic of the composite coating is 3D net texture. This research based on the flow components for slurry pump, so as to improve their surface modification technology level and the parts’ service life. The interface characteristics of different micro-areas for the composite fusion-infiltration coating with 3D net texture microstructure on 45# steel substrate are to be analyzed during the coating forming process. The effecting regularity of interact of the momentum, heat and mass transfer will be researched during the steel liquid penetrated through the capillaries among the preform at different micro-areas. The forming conditions and distribution of all kinds of phases among the texture coating are going to be investigated with the changing of forming parameters. The effect of texture on the mechanics properties is studied during their bending process. The deforming behavior of the “vein” and mesh” among the texture coating and wear resistance mechanics are going to be studied during the wear process. The quantificational microstructure-performance model is tried to set up based on the influencing mechanism of texture on wear performance, which will offer theoretical and technical base for the fabricating level of slurry pump with long service life and industrial application of fusion-infiltration technology.

以渣浆泵过流部件为研究对象，将复合材料理论与熔渗技术相结合，获得具有冶金熔合与3D立体网状织构组织特征的表面复合熔渗层，提高能耗型铸造成型钢铁件表面改性技术水平和使用寿命。研究45#钢表面具有3D立体网状织构组织特征的复合熔渗层在形成过程中织构的“筋络”与“网孔”的连接、各自区域内以及与基体距离不同的位置处微区内的界面特征；探讨基体金属液在预制层中的浸润流动动量变化、与渗剂之间热量-质量传输的耦合作用对织构“筋络”、“网孔”、“筋络”与“网孔”界面以及不同位置处的微区冶金互扩散的影响规律，揭示各工艺参数对织构的形成以及织构分布特征的影响；分析织构微区对整体复合熔渗层力学性能的影响特性，探讨织构“筋络”与“网孔”在摩擦磨损过程中的变形行为及减摩耐磨机制，尝试建立以滑动干摩擦性能为目标的织构特征与摩擦性能之间的关系模型，为长寿命渣浆泵过流件的制备水平与熔渗技术的工业化应用奠定理论基础。

以铸造成型渣浆泵为应用背景，由于其严重磨损与腐蚀而不得不频繁更换，该研究将耐磨耐蚀复合材料理论与其制造工艺相结合，采用真空熔渗技术在其表面制备一层耐磨耐蚀复合熔渗层，并对其微观组织、形成机制、硬度、力学协同性能、电化学及摩擦磨损性能进行系统研究。在热力学分析基础上以镍基合金+WC为渗剂，在45#钢零部件表面获得了近4mm厚具有3D网状织构型组织特征的复合熔渗层，基体与复合层之间存在近1mm的扩散冶金熔合区，复合熔渗层中包含镍基合金为主直径50~100μm的球形网孔区和截面宽度10~30μm的三维立体联通的网线区，WC主要分布在网线区，扩散冶金熔合区的主要成分为铁基固溶体与镍基固溶体，织构组织中网孔区主要成分为镍基固溶体、Ni3Fe、Cr3Ni2Si、Cr7C3、Cr23C6和NiB，而网线区的相组成主要有γ-Ni、Ni3Fe、Ni3Si、Ni3B、Cr7C3、Cr23C6、WC、W2C、C和Ni2.9Cr0.7Fe0.36；具有3D网状织构型复合熔渗层的形成过程为熔融钢液与预制层之间的渗流与热交换过程，二者之间交互耦合作用并相互促进；复合熔渗层的表面平均宏观硬度为HRC60左右，比基体提高3倍，复合熔渗层网孔区平均显微硬度为HV500~HV700，而网线区最大值可达到HV1800左右，当WC为30%时，表面带有网状织构型复合熔渗层的弯曲试样的弯曲强度可达584MPa，整体试样的弹性模量在熔渗层呈拉应力时大于呈压应力时的弹性模量，侧向弯曲时复合熔渗层与基体的变形与应力状态完全相同，断口显示其界面结合处并未出现任何开裂或微裂纹；电化学结果显示当WC含量为30%时具有3D网状织构型复合熔渗层的耐蚀性能优于弥散分布复合熔渗层，3D联通的立体网线成为球形区的保护层使得极化溶解腐蚀绕开这些区域而具有更好的耐蚀性；相同WC含量时，具有3D 网状织构组织特征复合熔渗层的摩擦磨损性能优于弥散分布复合熔渗层，摩擦过程中网线区成为均匀的载荷支撑网，每个突起的硬质相颗粒承载应力相比均匀弥散分布的硬质相颗粒承载应力小而不易碎裂成为磨粒，网孔区的磨屑氧化形成具有一定减磨作用的磨屑膜层，从而进一步提高了摩擦磨损性能。