Strengthening Mechanism Research And Structural Optimization Of Steel Water Nozzle

With the increase in demand for steel in national construction in recent years,the efficiency requirements for continuous casting steel production have gradually increased,and the performance requirements for ladle production equipment such as sliding nozzles have become higher and higher.The sliding nozzle is an important part of the ladle system.It is mainly divided into two parts,the upper and lower nozzles.It is the key equipment for injecting the tundish in the stable and safe molten steel in the ladle.The quality of the nozzle directly affects the efficiency of continuous production of molten steel.High-quality nozzles should have high strength and excellent thermal shock resistance.The structure of the internal flow passage of the nozzle also directly affects the impact of molten steel,which in turn affects the quality of the nozzle.Combined with the current research on zirconia-based composite materials at home and abroad,this paper mainly improves the quality of the nozzle by two methods:nozzle material improvement and internal structure optimization.The main research contents include:(1)Based on the physical matching and chemical matching theory of micro-nanoparticle composite and functional design,the molybdenum fiber-zirconia binary composite ceramic was designed and prepared,and the effect of molybdenum fiber addition on the properties of composite ceramics was investigated.The results show that adding a certain amount of molybdenum fiber can improve the mechanical properties of Zr02 ceramics and improve the thermal shock resistance compared with pure Zr02 ceramics.Especially the maximum flexural strength of molybdenum fiber composite ceramics have increased by about 45%than that without molybdenum fibers.When the content of molybdenum fiber is 2%,the mechanical properties and thermal shock resistance of molybdenum fiber-zirconia ceramics are optimal.(2)Combined with the research results of molybdenum fiber-zirconia binary composite ceramics,in order to continue to improve the mechanical properties and thermal shock resistance of ceramics,a third additive phase TiN was introduced,and a research scheme of zirconia-based ternary composite ceramics was developed.GTZ zirconia-based ceramics were prepared by dry compression molding-high temperature pressureless sintering process.The effect of TiN content on the properties of zirconia-based ceramics was investigated.The results show that the addition of TiN material further improves the mechanical properties of the composite ceramic and the thermal shock resistance is slightly improved compared with the performance of the molybdenum fber-zirconia ceramic without TiN material.In the dry pressing of ternary composites,the problem of poor quality of partial proportioning is encountered.In order to further explore the influence of the preparation process on ternary composite ceramics,The RTZ zirconia-based ceramics were prepared by vacuum hot pressing sintering process,and the effects of TiN content,sintering temperature and molding pressure on the properties of RTZ ceramics were investigated.The results show that the hot press sintering process can improve the strength and thermal shock resistance of ceramics compared with the performance of GTZ ceramics,and appropriate sintering temperature and molding pressure can further improve the comprehensive performance parameters of RTZ ceramics.Focus on RTZ ceramics with a TiN addition of 9%,and optimize the hot pressing process parameters with using XRD and SEM techniques.It was found that the overall performance of RTZ ceramics was best when the sintering temperature was 1600 ℃ and the molding pressure was 30 MPa.(3)Based on CFD theory,the numerical analysis of nozzle structure optimization was completed by using FLUENT software.Taking the actual working condition environment as the simulation condition,the analysis setting method and variable parameters are determined,and the optimized structure size under this working condition is obtained.In addition,on the basis of the optimization of the nozzle structure,the blank size is calculated and the mold material is selected,and the nozzle mold parts such as the female mold,the mold punch and the core rod are designed and assembled.