Effect Of Different Magnesium Raw Materials On The Properties Of Ladle Castables

With the requirements and development of modern steelmaking production technology,the erosion and damage of the ladle lining by molten steel is getting more and more serious,and the service life of ladle castables is becoming higher and higher.Corundum refractory is a refractory castable made of corundum as an aggregate and powder plus some binders.It has higher mechanical strength and corrosion resistance than high-alumina refractory castable and mullite refractory castable,but the thermal shock resistance is slightly worse.This article takes corundum castables for ladle lining as the main research object,uses plate-shaped corundum as aggregate,plate-shaped corundum powder,magnesia with different composition or sintered spinel powder,alumina fine powder as matrix,using pure calcium aluminate cement and silica fume as a binder,the porosity,bulk density,linear change rate and strength of castable samples after heat treatment at low temperature(110 ℃),medium temperature(1200 ℃),and high temperature(1600 ℃)were studied.The static slag resistance method is used to test the slag resistance of the sample after high temperature sintering.the X-ray diffractometer(XRD)was used to analyze the mineral phase of the sintered castable sample.the scanning electron microscope(SEM)was used to analyze the microstructure of the castable samples.Adding appropriate amount of magnesia fine powder and spinel fine powder to corundum castable can reduce the apparent porosity of the castable sample at low temperature,and promote the densification of the material,furthermore,the microstructure of the castable at room temperature is improved,and its mechanical properties at room temperature are improved.At the same time,the introduction of magnesia and spinel can also improve the slag erosion resistance of the castable,and improve the high-temperature use performance of the castable to a certain extent.With the same amount of magnesia,the volume density of the sample added with98 fused magnesia is the smallest,and the linear change rate is the largest.Especially after heat treatment at 1600 ℃,its strength is the lowest.the flexural strength and compressive strength at room temperature are 9Mpa and 130 Mpa,respectively.The sample with 97 fused magnesia has the highest compressive and flexural strength,and the slag erosion resistance performance is the best among the three magnesia.Comprehensive consideration,the appropriate amount of 97 fused magnesia is about6%.After the spinel sample was added with spinel,the porosity and linear change rate increased with the decrease of the size of the sintered spinel,and the bulk density and strength decreased.After the sample was treated at 1600 ℃,its linear change rate further increased,but it was still much lower than that of the castable sample with magnesia added,and the flexural strength and compressive strength were also lower than those of the castable sample with magnesia added.