Preparation And Mechanical Properties Of Nano Carbon Materials Reinforced Titanium Matrix Composites

Titanium matrix composite materials have been widely used in aerospace as well as automobile industry owing to their merit such as high specific strength,creep resistance and wear resistance.The properties of reinforcement are key factors in their performance.The novel nano-carbon materials including carbon nanotubes(CNT)and graphene oxide were used to reinforced Ti matrix composites owing to their high performance in this paper.These composites were prepared by ultrasonic dispersion,mechanical stirring,grind method and hot-pressed sintering.The agglomeration degree of CNT in Ti/CNT composites increased with CNT content especially in Ti/0.6 wt.%CNT composite.Microstructure morphology showed TiC were formed,and CNT were partially retained in the sintered composites.Ti/0.6 wt.%CNT composite exhibited maximum hardness 41.6% higher than pure titanium.Owing to serious agglomeration,its' yield strength was lower than Ti/0.4 wt.% CNT.On the contrary,GO were uniformly distributed in Ti/GO composites.No significant agglomeration could be observed until GO content rises above 2.5 wt.%.TiC and high density dislocation were formed and some GO are retained in composites.With increases in GO content,the hardness and yield stress increased.Ti/5.0 wt.%GO composites has maximum hardness 732 HV,137.7% higher than that of pure Ti and highest yield stress 1446.6 MPa,82% higher than pure Ti.These result showed GO had efficient strengthen effect in Ti/GO due to its' full potential has released.On the bases of the experimental results reported above,This thesis proposed to improve the strengthening effect of CNT from promoting its' dispersity by adding both GO and CNT into Ti.Interval timer shooting image and microstructure morphology of hybrid GO-CNT solution indicated that dispersity and stability of hybrid GO-CNT solution improved with GO concentration improved.Those results verified that GO improved the dispersity of CNT.Hybrid GO-CNT exhibited perfect dispersity in Ti/GO-CNT composites except GO content increases to 3.0 wt.%.a slight agglomeration could be observed in Ti/3.0 wt.%GO-0.6 wt.%CNT composites.TiC was formed in these composites,too.With GO content increased,the hardness decreased initially and then increased,and the yield strength went up all the way.Ti/3.0 wt.%GO-0.6 wt.%CNT composites exhibited highest hardness of 771.5 HV,150% higher than that of pure Ti,and maximum yield stress of 1387.1 MPa,74% higher than pure Ti.However,toughness of composites were decreased with GO content increased.The the mode of fracture changed from ductile to fragile by adding 3 wt.% GO.The strengthen effect of novel nano carbon materials reinforced Ti matrix composites mainly consist of Orowan strengthen effect of GO,CNT and in situ TiC,and efficient load transfer between GO,CNT and Ti.A better dispersity would incease both of these two strengthen effects.Comparison of properties of pure Ti,Ti/CNT,Ti/GO and Ti/GO-CNT composites reveal the enhancement effect of GO and CNT in Ti/GO-CNT composites are not just simple linear combination but synergy by interaction between them.