[机械装备再制造]超声振动辅助激光熔覆3540Fe/CeO2涂层实验及分析

为研究超声振动对激光熔覆的优化作用，在确定了最优工艺参数及粉末配比的基础上，采用超声振动直接施加于熔覆层的方式，进行超声振动辅助激光熔覆制备3540Fe/CeO2高性能熔覆层的实验研究。比较了振动的施加方式及施加角度对熔覆层宏观形貌、微观组织、物相组成及力学性能的影响。实验结果表明：超声振动对激光熔覆层形貌改善明显，当施加角度为45°时，效果最优。超声振动能在不改变相成分的情况下实现组织细化并减少气孔，涂层组织变为由γ（Fe，Ni）、Cr13Ni5Si2、Cr7C3等相组成的等轴晶及细小针状枝晶。加入超声振动后熔覆层平均硬度提高62%，达到了1 148 HV；摩擦因数显著减小，磨损量减少，耐磨性增强。通过对磨痕进行扫描电子显微镜（SEM）观察可以发现超声振动能改善磨损形式，试样磨损形式由粘着磨损为主变为规则的磨料磨损，磨损表面更为光滑。

Experiments and Analyses of 3540Fe/CeO2 Coatings by Ultrasonic Vibration Assisted Laser Cladding

To study the optimization effects of ultrasonic vibration on laser cladding, the method of ultrasonic vibration applied to the cladding layer directly was introduced to prepare the high performance cladding layers of 3540Fe/CeO2, on the basis of determining the optimal processing parameters and the powder proportions. The influences of the applying method and the applying angles of the vibration on the macroscopic morphologies, microstructures, phase compositions and mechanics properties of the cladding layers were compared. The experimental results show that ultrasonic vibration improves the morphologies of the laser cladding layers obviously, when the applying angle is as 45°, the effect is optimal. The ultrasonic vibration may refine the organization and reduce the porosity without changing phase compositions, the coating tissues are transformed into equiaxed crystals and fine needle-like dendrites composed of the phases γ(Fe, Ni), Cr13Ni5Si2, Cr7C3 and so on. After the ultrasonic vibration is added, the average hardness of the cladding layers increases by 62% and reaches 1 148 HV. The friction coefficient decreases significantly, the abrasion loss decreases and the wear resistance improves. Through the scanning electron microscope （SEM） observation of the abrasions, the ultrasonic vibration may improve the wear form, the wear form of the specimen changes from adhesive wear mainly to regular abrasive wear, and the wear surfaces are smoother.