Si对发动机用镍基合金电沉积NiCrAl涂层组织和摩擦学性能的影响

Effect of Si on Microstructure and Frictional Properties of NiCrAl Coatings Electrodeposited on Nickel-Based Alloys for Engine Applications

为了提高发动机用镍基合金Ni CrAl涂层表面的耐磨性能,以Si颗粒作为增强体,采用电沉积工艺制得NiCrAlSi涂层,并通过扫描电镜、X射线衍射仪、硬度测试仪、摩擦磨损测试仪等研究了其微观组织和摩擦学性能。结果表明:NiCrAlSi涂层中除了存在Ni、Cr与CrAl对应的衍射峰以外,还存在Si颗粒形成的衍射峰。涂层的表面没有形成微孔或裂纹,存在无规外形的Si颗粒,CrAl纳米颗粒依然可以在涂层内形成良好分散状态。加入Cr与CrAl颗粒,能够有效增大NiCrAl涂层的硬度至492 HV;采用Si颗粒作为NiCrAl涂层增强体时,可以使涂层的硬度增大近30%。NiCrAlSi涂层的摩擦系数保持相对稳定,在经过5 min磨损后其摩擦系数比NiCrAl涂层的更小。在NiCrAlSi涂层表面形成了疤痕形态的磨痕,同时降低了沟犁数量,几乎不存在磨粒,主要发生黏着磨损。

In order to improve the wear resistance of NiCrAl coating on nickel-based alloy for engine,the NiCrAlSi coating was prepared by electrodeposition technology with Si particles as reinforcement. The microstructure and friction properties of coatings were studied by scanning electron microscope(SEM),X-ray diffractometer(XRD),hardness tester and trobimeter. Results showed that NiCrAlSi coatings not only formed the diffraction peaks corresponding to Ni,Cr and CrAl,but also had diffraction peaks formed by Si particles. No micropores or cracks were observed on the surface of the coating,and the Si particles with random shape existed. Meanwhile,the CrAl nanoparticles could still form a good dispersion state in the coating. With adding Cr and CrAl particles,the hardness of NiCrAl coating was effectively improved to 492 HV.When the Si particles were used as the reinforcement of NiCrAl coatings,the hardness of coating could be raised by nearly 30%. Furthermore,the friction coefficient of NiCrAlSi coatings remained relatively stable and reached a smaller friction coefficient than that of NiCrAl coating after wear for 5 min. The NiCrAlSi coating surface formed scar-like wear scratches without abrasive particles,and the number of ploughs was reduced,which mainly belonged to the adhesion wear.