Ni-Co-P多元合金镀覆碳纤维增强Cu基复合材料的性能及断裂机制

Tensile Properties and Fracture Mechanism of Copper Matrix Composites Reinforced by Carbon Fibres with Ni-Co-P Alloy Coating

采用无钯化学沉积法在碳纤维(CF)表面沉积厚度约0.7μm、成分可控的Ni-Co-P合金镀覆层,并通过热压烧结工艺在850℃、30 MPa真空条件下分别制备纤维增强体体积分数为10%、20%、30%和40%的Ni-Co-P镀覆CF增强铜基复合材料CF/Cu(Ni-Co-P)、30%未修饰CF增强铜基复合材料CF/Cu和30%Ni镀覆CF增强铜基复合材料CF/Cu(Ni)。通过能谱仪、扫描电镜对CF/Cu(Ni-Co-P)中增强体及界面相元素分布、断口形貌进行观察,并采用电子万能试验机对复合材料拉伸性能进行测试。结果表明:在70℃水浴条件下沉积10 min可在CF表面获得厚度均匀、表面平整的Ni-Co-P多元合金镀覆层。CF/Cu(Ni)复合材料拉伸性能随着纤维含量的升高呈先提升后降低的趋势,30%CF/Cu(Ni-Co-P)复合材料的抗拉伸强度和屈服强度最高。在增强体含量相同条件下(30%),CF/Cu(Ni-Co-P)复合材料的力学性能明显优于CF/Cu(Ni)和CF/Cu复合材料,断裂机制为非积聚型失效。

The composition controlled Ni-Co-P multi-component alloy coatings with the thickness of about 0.7 μm were prepared on the surface of carbon fibres(CFs) using the palladium-free electroless plating. Then the copper matrix composites reinforced by the Ni-Co-P coated CFs, namely the CF/Cu(Ni-Co-P) composites, with CF content of 10vol%, 20vol%, 30vol%, and 40vol%, the uncoated CFs reinforced copper matrix composites(CF/Cu) with 30vol% CFs, and the Ni-coated CFs reinforced composites, namely the CF/Cu(Ni) composites, with 30vol% CFs were prepared by the vacuum heat pressure sintering at 850 ° C and 30 MPa. The distribution of reinforcement and interface phase elements and the fracture morphologies of the composites were observed by the scanning electron microscope and energy dispersive spectrometer. The tensile properties of different copper matrix composites were characterized by the electronic universal testing machine. Results show that the smooth Ni-Co-P coatings of uniform thickness can be obtained on CFs surface by electroless plating at 70 ℃ for 10 min. The tensile properties of CF/Cu(Ni-Co-P) composites are firstly increased and subsequently decreased with increasing the CFs content. The highest tensile and yield strengths are obtained for the30vol% CF/Cu(Ni-Co-P) composite. The mechanical properties of CF/Cu(Ni-Co-P) composite are obviously better than those of the CF/Cu and CF/Cu(Ni) composites with the same content of reinforcement(30vol%). The fracture mechanism of CF/Cu(Ni-Co-P)composite is non-accumulative fracture.