中文摘要：

在碳钢表面电沉积纳米晶Co-W合金镀层,电沉积过程中利用超声波作用提升镀层的表面硬度及耐蚀性。利用XRD、EDX和SEM对镀层的组成和微结构进行了分析。结果表明,纳米晶Co-W合金镀层为密排六方（hcp）结构,当引入40~100 W功率的超声波作用时,镀层更加平整紧密、内应力降低,镀层晶粒也得以细化;随着超声波功率的升高,镀层中钨含量不断增加;当镀层中钨的原子质量分数为26.51%时,镀层仍旧维持纳米晶状态。超声波作用下制备的镀层晶粒尺寸小、钨含量高、表面缺陷少,进而使得镀层的表面硬度和耐腐蚀性得以提升。

英文摘要：

Ultrasonic irradiation was utilized to improve the microhardness and corrosion resistance of Co-W nanocrystalline coatings on cabon steel substrate.The composition and microstructure of the coatings were characterized by XRD,EDX and SEM.The results showed that the coatings exhibited hexagonal close-packed（hcp）crystal structure,which became compact and smooth with the decrease of grain size and internal stress due to the application of a proper ultrasonic power（40-100W）.The tungsten content in coatings increased with the increase in the applied ultrasonic power.It is interesting to find that the coatings with tungsten content higher than 20% was not exhibit amorphous.Smaller grain size,higher tungsten content and lower density of surface defects favor the improvement of the hardness and of the corrosion resistance for Co-W nanocrystalline coatings.