Preparation and Properties of SiC-Graphite-Barite Composite Refractories

Author:Yin Zhao Zuo

Supervisor:huang chao zuo


Degree Year:2019





SiC-graphite-barite composite refractories were prepared,in order to meet the needs of graphite refractories for high temperature industry with high strength,good oxidation resistance,long service life and strong corrosion resistance.In view of the environmental pollution caused by the use of phenolic resin,new sugar binders were developed and some important research results were obtained.Graphite-SiC composite refractories were prepared by adding SiC with different particle sizes and phenolic resin as binder.When SiC content was 50 wt%,the apparent porosity,bulk density,flexural strength and compressive strength of graphite-SiC composite refractories were 29.98%,1.81g/cm~3,3.87MPa and 11.36MPa,respectively.Graphite-barite composite refractories were prepared by adding barite and phenolic resin as binder.When barite content was 10 wt%,the apparent porosity,bulk density,flexural strength and compressive strength of graphite-barite multiphase refractories were 33.45%,1.44g/cm~3,2.31MPa and 5.19MPa,respectively.SiC-graphite-barite composite refractories were prepared with different sizes of SiC,graphite and barite as main raw materials and phenolic resin as binder.When the content of SiC,graphite,and barite in SiC-graphite-barite composite refractories was64 wt%,27 wt%and 9 wt%,respectively,the comprehensive properties of the composite refractories were the best.Its flexural strength was 17.77MPa,compressive strength was 18.92MPa,the apparent porosity was 22.62%,and the bulk density was2.09g/cm~3,and the addition of excessive barite would affect the mechanical properties of the refractories,and the barite should be controlled below 10 wt%.It was concluded that the mechanism for obtaining strength of SiC-graphite-barite composite refractory was that the skeleton supporting of SiC with different particle sizes in the composite refractory system could improve the strength of the material.SiC-graphite-barite composite refractories with different carbohydrate bonds were prepared,and the strength acquisition mechanism of glucose,sucrose and starch as binders was obtained.After heat treatment,the carbonic network structure formed by carbohydrate bonds was distributed among the components of the composite refractories,resulting in the bonding effect,and the bonding effect of sucrose and phenolic resin was relatively better.The oxidation resistance of SiC-graphite-barite composite refractories bonded with different binders in carbon dioxide atmosphere and air atmosphere was studied.Phenolic resin and sucrose were the best binders.The anti-oxidation mechanism was that passivation and oxidation of SiC could improve the anti-oxidation ability of materials,and the encapsulation of barite on graphite could improve the anti-oxidation ability of graphite.Under high temperature and non-oxygen conditions,the material had excellent corrosion resistance to cryolite and waste lithium batteries,and the corrosion mechanism was"melt-infiltration".The research work is of great significance to corrosion resistant materials used for the extraction of rare earth metals and the recovery of waste lithium batteries,and lays a foundation for the development of new carbohydrate binders and high temperature corrosion resistant refractories.