| This thesis studies the influence of MnZn-ferrite production and processing technology on the magnetization of MnZn-ferrite powder.The research focuses on the influence of process parameters on the magnetization in the pre-sintering,grinding and spray granulation processes method and the control of the process parameters.This project is originated from the work of the author’s company,and the customers’demand for product quality improvement.The value of the project lies in analyzing the mechanism and influencing factors of material magnetism,which can effectively guide production enterprises to optimize product quality by adjusting process and equipment parameters.Through the project,the causes of magnetization changes in combination with actual production conditions are analyzed,and this can provide new ideas for the study of material characteristics from the perspective of manufacturing process control.This study uses the raw materials commonly used in the MnZn-ferrite industry to conduct experiments,and laboratory equipment and industrial production line equipment.The relationship between the magnetization characteristics of MnZn-ferrite materials and the production process to improve the stability of process control and product quality are analyzed.The main findings are as follows:1)The degree of magnetization can reflect the phase composition of the MnZn-ferrite powder to a certain extent.After the pre-sintering,the phase composition of the material changes.Except Fe2O3,the new phases are mainly ZnxMn1-xFe2O4 and Mn2O3.The magnetization numerical is positively correlated with the ZnxMn1-xFe2O4 phase content,and negatively correlated with the Mn2O3 phase content.2)The degree of magnetization can be controlled by adjusting the pre-sintering temperature.When the temperature of the material is between 900℃and 1000℃,the magnetization increases with the increase of the pre-sintering temperature.After the temperature exceeds980℃,the degree of magnetization highly increases.It is recommended that the pre-sintering temperature control range is 900℃～960℃.3)The degree of magnetization can be controlled by adjusting the amount of air in and out of the rotary kiln.The amount of air entering the kiln during the pre-sintering process directly affects the degree of magnetization.When the total air flow control range is 0.67m3/s to1.67m3/s,the magnetization increases by reducing the total exhaust air and the air intake at the kiln tail,and vice versa.4)The degree of magnetization can also be controlled by adjusting the cooling speed of the two sections of the rotary kiln’s.Heating kiln tube cooling section（from holding temperature to 450℃）,cooling speed control range 45℃/min～90℃/min,air flow control range 0.25m3/s～0.83m3/s.Cooling kiln tube cooling section（from 450℃to 100℃）,when the temperature control range is 35℃/min～60℃/min,the magnetization will increase by increase the cooling rate,and vice versa.5)The degree of magnetization is affected by the activity of the powder.The specific index of the powder during the production process is the specific surface area（BET）,which directly affects the rate and extent of the pre-sintering reaction of the material.The raw material activity can be controlled by milling time.6)The degree of magnetization is also affected by the spray granulation process.The irregular shape of the particles tends to make the material poor in fluidity,affects the quality of pre-sintering,and causes uneven magnetization.In terms of controlling particle distribution,increasing the proportion of coarse particles can increase the magnetization of the pre-sintering material to a certain extent,while increasing the proportion of fine particles can decrease the magnetization of the pre-sintering material to a certain extent. |
