Structural Design And Mechanical And Tribological Properties Of Carbon-graphite Materials For Machinery

Carbon graphite material for machinery is a kind of non-metallic material with great strategic value.It is widely used in the field of machinery industry due to its excellent properties such as high strength,high stability and self-lubrication.However,the fundamental reason for the insufficient mechanical and tribological properties of carbon-graphite materials is that it has inherent internal defects and secondary defects caused by insufficient matching between phases.Based on this,this thesis aims to prepare high-performance mechanical carbon-graphite materials,and design the raw materials according to the physical and chemical properties of different components and the interaction mechanism between them.In-depth analysis of the relationship between aggregate particle size,specific surface area and pitch content was conducted,and a controllable method for structural design and performance regulation of high-strength mechanical carbon-graphite materials was summarized.At the same time,impregnated carbon-graphite materials with excellent tribological properties at high temperature were prepared by zinc phosphate impregnation-curing treatment,revealing the anti-oxidation and wear-reducing mechanism of zinc phosphate on the high-temperature friction and wear properties of carbon-graphite materials.The main research contents are as follows:(1)By comparing the physical and chemical properties of two different pitch cokes and three pitches themselves,the raw material design of carbon graphite materials for machinery is carried out.The research shows that the 2#pitch coke composed of a large number of fine and medium mosaic structures with isotropic pitch carbonized structure as the substrate has the characteristics of good homogeneity,structural compactness,high elastic modulus and high stability,and is a good preparation method.Preferred aggregate for high-strength,high-density mechanical carbon-graphite materials.1#pitch has the best quinoline insoluble content,the lowest softening point and relatively high coking value,which can be used as the preferred binder for the preparation of carbon graphite materials for machinery.(2)Based on the test and characterization of the structure and performance of the primary calcined body,the internal relationship between different aggregates and the optimal asphalt content ratio was constructed,and the referenc e method for evaluating the optimal asphalt content by using the aggregate specific surface area was summarized.The research shows that the mechanical carbon graphite material developed based on aggregate structure design,aggregate/binder activity compat ibility,uniform kneading and densification process has excellent comprehensive properties(density 1.59 g/cm~3,flexural strength 54 MPa),compressive strength 195 MPa,friction coefficient 0.09).(3)A certain type of carbon graphite material(GB)was de veloped outsourcing by the method of forward design.After phosphate impregnation-curing treatment,impregnated zinc phosphate carbon graphite material(IGB)with excellent oxidation resistance and tribological properties at high temperature was obtained.The friction coefficient of IGB at high temperature is 95%lower than that of GB,and the anti-oxidation performance is improved by 15%.Through the structural characterization and chemical composition analysis of the wear surface,the graphite,C-O-P bonds and the iron metaphosphate/zinc large-area boundary lubricant layer formed on the IGB wear interface were found,and the high temperature friction and wear performance of the lubricant layer on the carbon-graphite material was revealed.anti-oxidative and anti-wear mechanism.In this paper,carbon-graphite materials for mechanical use were prepared by the method of forward design,and the intrinsic relationship between aggregate particle size distribution,specific surface area and asphalt content was e xplored,and the anti-oxidation and wear-reducing mechanism of zinc phosphate on the high-temperature friction and wear properties of carbon-graphite materials was revealed.It provides theoretical support for solving the problems of difficult matching of multi-components of carbon-graphite materials,insufficient mechanical properties,and poor high temperature oxidation resistance and wear resistance.