Preparation And Properties Of Titanium Matrix Composites Based On Modification And Dispersion By Graphene

Carbon nanomaterials such as graphene are widely used as one of the ideal reinforcements for metal matrix composites due to their excellent mechanical properties.However,the large density difference between graphene and metal titanium matrix and the strong van der Waals force between graphene sheets make it easy to agglomerate in the matrix,which seriously restricts the application and development of graphene/metal matrix composites.Based on the above questions,this study uses ceramic particles（Al₂O₃）and organic solvent（D400）to modify graphene oxide（GONs）to improve the dispersion ability of graphene in TC4 matrix,and at the same time achieve the joint effect of modifier and graphene on graphene oxide.The powder morphology,phase composition,microstructure,fracture morphology,etc.of composites prepared by the two modified methods were characterized by scanning electron microscope（SEM）,transmission electron microscope（TEM）,X-ray diffractometer（XRD）,thermogravimetric analyzer（TGA）and X-ray photoelectron spectroscopy（XPS）.In addition,the tensile properties and hardness of the composites were tested.The main conclusions of the paper are as follows:The effects of different precipitation temperatures on the morphology and chemical state of the nanopowders were investigated.The results show that the rGONs@Al₂O₃ nanopowders are composed of 21.6wt%rGONs and 78.4wt%Al₂O₃;during the preparation process,the graphene oxides were reduced to reduced graphene oxides,the number of alumina particles decreased with the increase of the precipitation temperature,and the optimum preparation temperature of the nanopowder is 60℃.The effect of rGONs@Al₂O₃ nanopowders content on the microstructure and properties of titanium matrix composites were studied.Alumina particles were precipitated in the rGONs@Al₂O₃/TC4 composite,and the grains were obviously refined.The mechanical properties test results show that the yield strength and tensile strength of the 0.5rGONs@Al₂O₃/TC4 composite are 950.5 MPa and 1022.5 MPa,which are 20.3%and 17%higher than those of the pure TC4 matrix,respectively.The fracture mechanism of composites changed from original ductile fracture to mixed fracture.The microstructure evolution and mechanical properties of GONs/TC4,D400/TC4 and GOMs/TC4 composites were compared and analyzed.The study found that there are some differences in the morphology of TiC formed by graphene oxide and polyetheramine,the former TiC is in the form of flakes,and the latter is in the form of micron-sized particles.The yield strength and tensile strength of the 0.3GOMs/TC4 composite are 963.45 MPa and 1062.37 MPa,respectively,and the elongation is 7.8%,realizing the co-strengthening of the TC4 matrix by graphene oxide and polyetheramine.A large number of TiC particles can be observed in the fracture morphology of GOMs/TC4 composites,and with the increase of GOMs content,the cleavage steps become more obvious.The advantages and disadvantages of the two modification methods in the application of titanium matrix composites were compared,it can be seen that modification is one of the effective ways to improve the dispersion ability of graphene in the titanium matrix,and at the same time,the modifier and graphene can jointly strengthen the titanium alloy matrix.However,compared with ceramic particle modification,organic solvent modified graphene has better potential in the preparation and processing of high-performance titanium-based composites.