Study On Relationship Between Pore Related Parameters And Permeability Of Refractory Castables During Heating

Dense refractory castables are prone to explode during rapid heating.The permeability is an important parameter to evaluate the explosion resistance during heating.Study on the relationship between permeability of refractory castables and the pore related parameters is advantageous to improve the permeability of castables during heating and improve explosion resistance,and is helpful to design the new materials by means of the research methods.In order to study on relationship between pore related parameters and permeability of castables,alumina based castables bonded by low cement,ultra-low cement and MgO-SiO₂-H₂O were used as target materials.The castables samples with different pore related parameters were prepared by heat treatment with different temperature and time.The effect of drying system on pore related parameters and permeability of castables was investigated,and the relationship between permeability and pore structure of refractory castables was analyzed by multivariate linear regression and grey relational degree analysis method.The conclusions are summarized as follows:?1?Due to the dehydration characteristics of alumina based castables during heating,the porosity,average pore diameter and pore tortuosity showed regular changes with the change of drying system.For low cement castables,with the increase of heating temperature,the average pore size decreased,while the porosity and pore tortuosity increased.When the heating temperature is fixed,except 100?and 200?,porosity,average pore diameter and pore tortuosity of low cement castables after pre-drying have a tendency to remain unchanged with change of the heating time.For ultra-low cement castables,when the heating temperature is fixed,the porosity,average pore diameter and pore tortuosity after pre-drying were unchanged with the change of heating time,the castables porosity and pore tortuosity increased with the heating temperature increasing,while the average pore diameter decreased with the heating temperature increasing.For MgO-SiO₂-H₂O bonded castables,when the heating temperature is fixed,the porosity,average pore diameter and porosity after pre-drying are unchanged with the change of heating time;when heating time is fixed,with the increase of heating temperature,porosity and average pore size increased,while pore tortuosity decreased,and after 200?,the porosity,average pore size and pore tortuosity remained unchanged.?2?The permeability of cement bonded castables show regular changes with the change of heating system in the drying process.For low cement castables,when the heating temperature is fixed,the change of permeability after pre-drying with heating time keeps constant;when the heating time is fixed,the permeability increases with the increase of heating temperature.For ultra-low cement castables,the permeability after pre-drying remains unchanged with the heating time changed.When heating time is fixed,the permeability increases with the increase of heating temperature,and after 400?,the permeability remained unchanged.For MgO-SiO₂-H₂O bonded castables,permeability with the heating system changes did not show regular changes.?3?The permeability of refractories is closely related to its structure parameters.The model of quantitative relationship between permeability and pore related parameters was proposed,which is k=B×?^2.5×D^-0.5?B is the empirical constant,?is the porosity and D is the average pore diameter?.It can be well evaluated quantitative relationship between permeability,porosity and average pore size of corundum cement bonded refractory castables.?4?Pore of different sizes show different effects on permeability of castables.For low cement castables,the porosity at 0.3-0.1 um has the most influence on the permeability.For ultra-low cement castables at 100?and 300?,the porosity at?0.1 um has the most influence on the permeability of castables;when at 600?,the porosity at 1-0.3 um has the most influence on the permeability.For MgO-SiO₂-H₂O bonded castables,the porosity at1-0.3 um has the most influence on the permeability.