碳微球表面功能化对镁基复合材料的增强作用

Influence of Surface Functionalization on Properties of Carbon Microspheres Reinforced Magnesium Composites

纳米碳材料增强相与镁基体间的两相界面结合程度直接影响着复合材料性能的提高,而使用化学改性法对增强相进行表面功能化可以有效改善两相间的界面结合度。为了进一步研究表面功能化在提升复合材料性能上所起的作用,本研究选用CVD法和水热法制备的碳微球(CVD-CMSs和HT-CMSs)为增强相,一是使用一步改性法(即使用表面活性剂PVP直接处理)对增强相进行表面功能化处理,制备出CVD-CMSs/Mg和HT-CMSs/Mg,考察CMSs上接枝的含氧官能团对表面功能化处理的效果;二是使用两步改性法(即先使用化学沉积法将MgO颗粒裹附到碳球表面,再用PVP进行处理)对增强相HT-CMSs进行功能化处理,并制备出HT-CMSs@MgO/Mg,与HT-CMSs/Mg对比来考察HT-CMSs上负载MgO纳米颗粒的作用。采用傅里叶红外光谱仪、X射线衍射仪、光学显微镜、高分辨透射电子显微镜和拉伸性能测试仪等对复合材料样品的组织、界面结构和力学性能进行表征和分析。结果表明:CMSs上携带的含氧官能团对表面功能化处理的效果以及增强相的分散性都具有积极作用,且经PVP一步改性后制得的复合材料的增强相与基体间有MgO薄膜生成,改善了增强相与基体的相容性;经两步改性后,负载在HT-CMSs表面的MgO纳米颗粒使两相间的MgO膜增厚,进一步提升了两相间的界面结合度,起到有效连接增强相与基体界面的作用,并最终使复合材料的拉伸性能得到提高。

The enhanced mechanical properties are influenced by interfacial bonds between carbon nano-material reinforcement and magnesium matrix immediately.Surface functionalization of reinforcement by chemical modification could improve the interface bonds effectively.For research the role of surface functionalization in improving properties of composites deeply,the carbon microspheres(CMSs)which prepared by chemical vapor deposition method(CVD-CMSs)and prepared by hydrothermal method(HT-CMSs)were used as reinforcements in this work.Firstly,one-step modification was used to functionalize the reinforcements respectively,and then the magnesium matrix composites CVD-CMSs/Mg and HT-CMSs/Mg were prepared by spark plasma sintering and hot extrusion.The effect of oxygen functional groups which grafted on CMSs by chemical modification was investigated.Secondly,the HT-CMSs reinforcements were functionalized by two-step modification,after that,the magnesium matrix composites HT-CMSs@MgO/Mg were prepared.The impact of MgO nanoparticles coated on HT-CMSs was investigated by compared with HT-CMSs/Mg.Interface structure and mechanical properties of the samples were characterized by Fourier transform infrared spectroscopy,X-ray diffraction,optical micrographs,high-resolution transmission electron microscopy and tensile testing.The results show that oxygen functional groups of carbon microspheres have positive effects on the surface functionalization and dispersion of reinforcing phase.The MgO films,produced between reinforcement and matrix during their fabrication after one-step modification,are effectively promoting the interface compatibility of two phases.MgO nanoparticles coated on the surface of HT-CMSs by CVD play a bridge role between carbon microspheres and matrix,which is beneficial to increase the thickness of MgO films and improve the tensile property of composites.