The Study On The Composition And The Property Of MgO-CaO-ZrO₂ Submerged Entry Nozzle

In this thesis , the composition and the property of Basic material MgO-CaO-ZrO2 both including carbon and free-carbon has been studied. Though the selection of raw material ,blending, mixing, forming, heat treatment or high temperature fining, and erosion test by immersion bar and static crucible method though steel and scoria erosion, analyse the structure by SEM and ED AX in a microscopic way, measure the compressive strength bend strength volume density and the porosity.The experiment indicates that the inducting of ZrO2 to MgO-CaO-ZrO2 material plays certain role in physical property; the material should not be treated in high-temperature of 1000 C, but rather only in low temperature. In the erosion test, a decarburization layer is formed on the surface between material and steel. The structure of this area is loose, which provides a path for steel erosion and penetration. The CaZrO3 formed in high temperature distribute in agglomeration in the crystals, fills in the path after the graphite's oxidation, and resists the erosion of scoria effectively. The principle of anti-alumina buildup is that, the low melting material reacted by CaO and Al2O3, SiO2 in the scoria forms a glass phrase on the surface of test coupon, which made Al2O3 hard to build up. And also the MgO-CaO- ZrO2 material free carbon, with 15% ZrO2 fired in 1630 C, direct bonding of CaZrO3 formed in high temperature fining and periclase has the excellent erosion resistance, whose property is similar to that in 1600 C. With the increase of ZrO2 in the same temperature, the erosion resistance of material decreases. When the material is reacted with scoria, the main process is the erosion of scoria and the reaction of material with the Fe, Al, Ca penetrated. The C4AF, CA low melting materials produced decrease the erosion resistance of the material.