Study On Preparation And Properties Of Basalt Fiber Reinforced Copper Matrix Composites

Basalt fiber has many advantages such as high strength,good corrosion resistance,low density and green environment protection.They are widely used in composite materials,friction materials,heat insulation materials,filtration materials and other fields.In particular,basalt fibers are often used as the reinforcing phase of composite materials.Such as basalt fibers can be used to reinforce resin,cement,etc.However,basalt fibers are relatively little used in metal matrix composites.In view of the high performance and low cost of basalt fibers,in this thesis,basalt fibers are used to construct copper matrix composites to improve their mechanical and tribological properties.Due to the high temperature sintering required for copper matrix powder metallurgy composites,the effects of heat treatment atmosphere,temperature and other process parameters on the structure,phase composition and mechanical properties of basalt fibers were firstly investigated in this paper.On this basis,basalt fiber reinforced copper matrix composites were prepared by powder metallurgy method,and the effects of sintering method,sintering temperature,basalt fiber addition and other factors on the densities,microstructures,mechanical properties and tribological properties of the composites were investigated.The tensile strength of basalt fibers decreases with the increase of heat treatment temperature.Under the same heat treatment temperature conditions,the strength of basalt fibers after vacuum heat treatment was significantly higher than that of basalt fibers after air atmosphere treatment.On the one hand,air heat treatment leads to uneven distribution of basalt fiber composition and is prone to surface defects.On the other hand,the Fe²⁺ions in the air heat-treated fibers oxidized to Fe³⁺ions,which in turn maintained the amorphous structure of basalt fibers.On the contrary,vacuum heat treatment retained more Fe²⁺ions,which promoted the crystallization of basalt fibers,and thus improved the mechanical properties of basalt fibers after heat treatment.Under the same sintering temperature,the mechanical properties of the basalt fiber reinforced copper matrix composites prepared by spark plasma sintering were significantly better than those of hot press sintering.With the increase of basalt fiber content,the hardness of basalt fiber reinforced copper matrix composites gradually increased,the relative density slightly decreased,and the tensile strength first increased and then decreased.The tensile strength of the composites reached a maximum of 276 MPa when the basalt fiber addition was 1.5 wt.%.With the increase of sintering temperature,the tensile strength of the composites gradually decreased.The reason for this is that the strength of the basalt fiber itself decreases as the sintering temperature increases,which in turn leads to a weakening of its strengthening effect.The friction coefficient and wear morphology of the basalt fiber reinforced copper matrix composites were influenced by three aspects:the mass fraction of basalt fiber added,the sintering temperature,and the test load.The friction coefficient increased with increasing sintering temperature and test load.The friction coefficient decreased with increasing basalt fiber content.The minimum average coefficient of friction of the composite was 0.5020.The main forms of wear are abrasive wear and spalling wear.