摘要
利用纳米压痕和纳米划痕试验表征了仿生叠层构型铝基石墨烯复合材料(Bio-inspired laminated graphene reinforced aluminum martrix composite,BAMC)与纯铝的力学性能和摩擦磨损性能.鉴于摩擦力由黏着作用和犁沟作用两分量共同组成,对比探究了BAMC与纯铝在微观摩擦磨损过程中的弹塑性转变过程,分析了黏着作用与犁沟作用在摩擦力中的贡献度,揭示了其微观摩擦磨损机制.结果表明:相较于纯铝,BAMC的纳米硬度提高了约24%,总摩擦系数(Friction coefficient)降低了约28%,黏着作用分量和犁沟作用分量分别降低了32%和16%.换言之,复合材料中的异质界面产生异质变形诱导强化,进而增强了应变硬化,使仿生叠层石墨烯铝基复合材料的硬度得到明显提升,并且仿生叠层构型的石墨烯主要通过降低黏着作用来实现减磨.从微纳米尺度揭示了BAMC的力学性能和摩擦磨损性能显著提升的机理,可为提升其摩擦磨损性能提供理论依据.目前的工作通过纳米划痕和纳米压痕强调了叠层结构石墨烯的添加对块体复合材料的摩擦性能的影响,并表明仿生叠层构型铝基石墨烯是搭建仿生叠层结构的小尺寸理想增强体.
Natural biological materials(such as bones,shells and spider silk,etc.)have evolved for a long time to obtain an ideal laminated structure composed of different materials arranged alternately,and consequently acquire excellent properties.As one of emerging two-dimensional nanomaterials,graphene has attracted more and more attentions,which is an ideal reinforcing component to construct bio-inspired laminated structure.Nevertheless,there are still several problems to restrict the use of graphene.For example,the structural integrity of graphene is often difficult to be guaranteed through ball milling during conventional powder metallurgy process.In addition,it is very challenging for graphene to reliably coat the contact points between the spherical powders.Moreover,currently,most of the relevant studies on biomimetic laminated graphene composites focus on the strengthening and toughening mechanism,and few studies focus on the microscopic friction,which can help reveal the intrinsic friction mechanism.In this work,nanoindentation and nanoscratch were used to study the mechanical properties and friction and wear properties of bio-inspired laminated aluminum matrix composite(BAMC).Herein,by assembling aluminum flakes cladded with graphene,BAMC inspired by natural biological materials was designed and prepared by means of improved powder metallurgy.The structural integrity of graphene can be ensured to the greatest extent by avoiding the structural destruction of graphene in the ball milling process.With the continuous update of material characterization technology,nano-testing technology has been widely used.Nanoscratch and nanoindentation testing techniques have mainly been used to characterize and analyze the mechanical properties of materials,critical depth of elastoplastic transition,microscopic deformation behavior,and friction and wear properties by single asperity.The complex surface interactions during macroscopic wear still remain to be a challenge to understand.Apparently,nanoscratch and nanoindentation testing techniques have the advantage to implement sliding asperity contact of a single point,from which the wear resistance of composites can be concluded.Especially,through contrasting the ramping code and the constant mode,nanoscratch can also be used to study the influence of micro-scale and nano-scale microstructure on friction properties.It can be inferred that,the nanoindentation and nanoscratch are in favor of establishing a relationship between the nature of microscopic friction and macroscopic experimental phenomena.As a consequence,mechanical properties and tribological behaviors of the pure Al and the BAMC were characterized by the nanoindentation test and the nanoscratch test.Based on the scanning electron microscopy and transmission electron microscopy results,the graphene was robustly bonded with the matrix,which possessed continuous,complete and clear layered stacking structure.Friction was composed of two components,i.e.,adhesion and ploughing.Then,nanoindentation and nanoscratch were used to explore mechanical properties and the elastic-plastic transformation in the microscopic friction and wear process of BAMC and Al.Evidently,nanoscratch test was beneficial to analyze the contribution from the adhesion and ploughing,and revealed the microscopic friction and wear mechanism.The results showed that,compared with Al,the nanohardness of BAMC increased by about 24%,and the friction coefficien reduced by about 28%.The adhesion component and the ploughing component decreased by 32%and 16%,respectively.Upon nanoindentation on the biomimetic laminated structure,heterogeneous deformation induced strengthening occurred at the interface of graphene in the composites,which intensified the strain hardening ability and improved the hardness of BAMC.In the nanoscratch,the planar stacking of graphene can reduce both the adhesion and ploughing forces simultaneously,and the reduction of adhesion was dominant.The heterogeneous deformation induced strengthening and the adhesion reduction induced by graphene layers jointly improved the friction and wear resistance of BAMC.The reasons for the significant improvements of the mechanical properties,friction and wear properties of the BAMC were revealed from the micro-scale and nano-scale by using nano-testing technology,which might provide a theoretical basis for improving the friction and wear properties of the BAMC.
作者
叶雯婷
周青
罗大微
李赞
陈小林
王显宗
王海丰
管仁国
YE Wenting;ZHOU Qing;LUO Dawei;LI Zan;CHEN Xiaolin;WANG Xianzong;WANG Haifeng;GUAN Renguo(State Key Laboratory of Solidification Processing,Center of Advanced Lubrication and Seal Materials,Northwestern Polytechnical University,Shaanxi Xi'an 710072,China;State Key Laboratory of Metal Matrix Composites,Shanghai Jiao Tong University,Shanghai 200240,China;Engineering Research Center of Continuous Extrusion,Ministry of Education,Dalian Jiaotong University,Liaoning Dalian 116028,China)
出处
《摩擦学学报》
EI
CAS
CSCD
北大核心
2022年第2期338-346,共9页
Tribology
基金
国家自然科学基金项目(51871184和51801161)
陕西省自然科学基础研究计划(2019JQ-020)资助。
关键词
石墨烯
金属基复合材料
仿生构型
纳米摩擦性能
硬度
graphene
metal matrix composites
bio-inspired laminated architecture
nano-tribological properties
hardness