化学复合镀Ni-Mo-P/CeO_(2)镀层结构与摩擦学性能研究

Study on the Structure and Tribological Properties of Electroless Composite Ni-Mo-P/CeO_(2) Coatings

为研究CeO_(2)稀土添加对Ni-Mo-P化学镀层结构及性能的影响,采用化学复合镀技术,在GH4169镍基高温合金表面制备Ni-Mo-P镀层、Ni-Mo-P/CeO_(2)复合镀层,并对其进行400℃热处理。利用SEM、EDS、XRD对镀层组织结构、元素组成、相结构进行分析。采用显微硬度计、纳米压痕仪、球-盘式摩擦磨损试验机、三维表面轮廓仪对镀层力学性能和摩擦学性能进行分析。结果表明:Ni-Mo-P镀层分布有典型的球状结构,为纳米晶和非晶混合的混晶态结构,结晶化程度只有16%。加入CeO_(2)颗粒后Ni-Mo-P/CeO_(2)复合镀层内分布有孔洞,镀层粗糙度增加,镀层结晶化程度提高至51%。400℃热处理后镀层内析出纳米晶Ni_(3)P相,镀层结晶度增大,镀层内孔洞消失,组织致密度获得改善。添加CeO_(2)颗粒使镀层的硬度有所降低,热处理可明显提高镀层的硬度;热处理后Ni-Mo-P镀层硬度(HV)从镀态的6321 MPa上升至13504 MPa,Ni-Mo-P/CeO_(2)复合镀层硬度(HV)由镀态的5351 MPa提高至11182 MPa。400℃热处理可以明显提高镀层的耐磨性能;CeO_(2)颗粒的添加提高了镀层的韧性,抑制了磨损过程中裂纹的产生,使得复合镀层具有优良的耐磨性能。

In order to study the effect of CeO_(2)addition on the structure and performance of Ni-Mo-P electroless plating coatings, Ni-Mo-P coatings and Ni-Mo-P/CeO_(2)composite coatings on the surface of GH4169 nickel-based superalloy were prepared by electroless composite plating technology. The influence of the heat treatment at 400 ℃ on the structure and properties of the coatings was also investigated. The microstructure,element composition, and phase structure of the coatings were analyzed by SEM, EDS and XRD, respectively. The mechanical and tribological properties of the coatings was analyzed by microhardness tester, nanoindenter, ball-disk friction and wear tester, and three-dimensional surface profiler. The results show that the Ni-Mo-P coating exhibits a typical spherical structure with nano and amorphous mixed crystalline structure. The crystallinity of the coatings is only 16%. The addition of CeO_(2)particles in the Ni-Mo-P/CeO_(2)composite coatings induces the voids in coatings and promotes the coarseness in morphology. The crystallinity of the mixed crystalline structure increases to 51%. The heat treatment has positive effect on the structure of the coatings, such as promoting the precipitation of Ni_(3)P nano phase, increasing the crystallinity, eliminating the voids and promoting the density. The hardness of the coating is reduced with CeO_(2)addition. However, the hardness of the coatings is improved significantly by heat treatment. The hardness of the Ni-Mo-P coating increases from 6321 MPa in the plating state to 13504 MPa in the heat treatment state, and the hardness of the Ni-Mo-P/CeO_(2)composite coating increases from 5351 MPa in the plating state to 11182 MPa in the heat treatment state. The wear resistance of the coatings is improved obviously after heat treatment. The addition of CeO_(2)particles to the coatings can enhance the toughness of the coatings, and inhibit the occurrence of cracks during the wear process, thus making the Ni-Mo-P/CeO_(2)composite coating have the best wear resistance.