【作者】 欧雪梅；

【导师】 葛世荣；

【作者基本信息】 中国矿业大学 ， 机械设计及理论， 2009， 博士

【摘要】 聚合物基复合材料的界面结合状况往往是影响其摩擦学性能的关键。本论文选择针状硬质的硅灰石和片状软质的石墨两种矿物填料,用湿化学法对硅灰石表面进行纳米TiO₂和SiO₂包覆处理,对石墨表面进行SiO₂包覆处理,考察纳米包覆处理对矿物填充尼龙1010复合材料的界面结合性能的影响,探讨纳米包覆处理对复合材料摩擦学性能的影响机理。本实验用扫描电子显微镜（SEM）,透射电子显微镜（TEM）,能谱仪（EDS）,傅立叶红外光谱（FTIR）,X射线衍射（XRD）,X光电子能谱（XPS）等手段对包覆层进行表征。并结合XRD对包覆后颗粒填充尼龙1010复合材料进行的聚集态结构分析, DSC/TG对复合材料热稳定性的分析,以及SEM和光学显微镜对拉伸断口和磨损表面形貌进行的分析,探讨纳米包覆层对聚合物基复合材料结构的影响及其对材料摩擦学性能的作用机理,得到了如下主要结论:实验制备的TiO₂包覆硅灰石、SiO₂包覆硅灰石和SiO₂包覆石墨三种包覆颗粒,填充尼龙1010制成复合材料时,均具有诱导结晶作用,并因此获得高的界面结合强度。由于TiO₂包覆层对尼龙基体的热分解具有催化活化作用,导致化学磨损,因此虽然TiO₂包覆硅灰石填充尼龙1010可获得摩擦系数的降低,但磨损率却比未处理硅灰石填充尼龙1010复合材料的高。然而经硬脂酸处理,促进了结晶,并降低了包覆层的催化活性,抑制了化学磨损,使摩擦系数和磨损率均获得降低。SiO₂包覆处理后的石墨具有良好的诱导结晶性,使尼龙1010复合材料的界面结合强度提高,易获得转移膜。同时SiO₂包覆石墨可提高尼龙1010基体的热稳定性,因此摩擦系数和磨损率均低于未处理石墨。硅烷偶联处理SiO₂包覆处理石墨使诱导结晶作用减弱,复合材料磨损率进一步降低,但摩擦系数提高。但由于石墨的抗剪切能力差,在30%含量时,各种处理石墨颗粒填充的复合材料的均比纯尼龙1010的耐磨性差。硅灰石表面包覆的SiO₂膜,既具有对尼龙1010的诱导结晶作用,又可提高基体尼龙的热稳定性,在本实验的成分范围内（10%³0%）,均比未处理硅灰石填充的复合材料的摩擦系数和磨损率降低。在含量为20%时,比硅灰石填充尼龙复合材料的摩擦系数和磨损率分别降低了43.3%和81.2%。硅烷改性处理后,复合材料的摩擦系数和磨损率进一步降低。在含量20%时,摩擦系数和磨损率比未经硅烷处理的分别降低了28.1%和41.7%。本文认为纳米包覆处理提高尼龙1010复合材料摩擦学性能的作用机理是:纳米包覆层诱导尼龙1010基体结晶,结晶层既提高界面结合强度,又易于发生向对偶面的转移,因此使摩擦系数降低。而磨损率的变化受包覆层对基体尼龙热稳定性作用的影响。偶联剂处理提高了包覆颗粒与尼龙1010的界面结合强度的,使磨损率进一步降低。而对摩擦系数影响取决于其对结晶状况的影响。更多还原

【Abstract】 The interface bonding of polymer matrix composite was considered as the key factor of tribological properties. In this paper three kinds of polymer composites were prepared, by filling hard spiculate wollastonite with SiO₂ and TiO₂ nano-coating and soft flaky graphite with SiO₂ nano-coating into nylon 1010 respectively. The effect of nano-coated layer on interface bonding was investigated, as well as the mechanism of effects on tribological behaviors of the composites was discussed.The nano-coatings were characterized by scanning electron microscope（SEM）, transmission electron microscopy （TEM）, energy dispersive X-ray spectroscopy （EDS）, Fourier transform infrared spectroscopy （FTIR）, X-ray diffraction （XRD）, and X-ray photoelectron spectroscopy （XPS）, respectively. The mechanical and tribological properties of composite containing different filling amount were investigated. Furthermore, the aggregate state structure, thermal stability, topography of wear surface and cross section were analyzed by XRD, differential scanning calorimeter （DSC）、thermogravimetry（TG）, SEM and microscopy, respectively. The main conclusions were drawed as following.The composites obtained high interface bonding strength after filled with TiO₂-coated wollastonite、SiO₂-coated wollastonite, and SiO₂-coated graphite, which induce nylon 1010 crystallization.Although nylon 1010 filled with TiO₂-coated wollastonite could decrease the friction coefficient, the wear rate of composite is still higher than that of nylon 1010 filled with wollastonite, because of chemical wear due to the catalysis activation of TiO₂ coating layer during thermal decomposition of nylon substrate. However, further stearic acid treatment of TiO₂-coated wollastonite surface could help to increase crystallization of nylon 1010, decrease the catalysis activation of coated layer, thus restrain chemical wear and decrease both friction coefficient and wear rate. Graphite with SiO₂ coating could increase the interface bonding strength, help to the formation of transfer film and increase the thermal stability, resulting in the smaller coefficient and lower wear rate of composite. Graphite with SiO₂ coating by silicone coupling could further decrease the wear rate of composite, but increase the friction coefficient. The composite with 30% graphite under different treatments has worse wear resistance than nylon 1010, due to bad shear resistance of graphite.Wollastonite with SiO₂ coating could induce the crystallization of nylon and increase the thermal stability of nylon matrix, thus resulted in low friction coefficient and wear rate. In comparison with being filled wollastonite, friction coefficient and wear rate of composite filled with 20% SiO₂-coated wollastonite decreased by 43.3% and 81.2% respectively. And friction coefficient and wear rate of composite filled with 20% wollastonite with SiO₂-coated after silicone coupling decreased by 28.1% and 41.7% further.All of the results suggested that the tribological mechanism of nylon 1010 filled with nano-coating was as following. Nano-coating could induce crystallization of nylon 1010. On the one hand, improved crystallization increases the interface bonding strength and is beneficial to the formation of transfer film, which resulted in the decrease of friction coefficient. The other hand, coating has effect on the thermal stability of nylon matrix, which could significantly affect the wear rate. Futhermore, coupling treatment increased interface bonding strength of nylon 1010 filled with coated particles and decreased the wear rate. And the friction coefficient depends on the crystallinity of nylon matrix in the composite.更多还原