Heating Characteristics And System Optimization In Vacuum Sintering Furnace

As one of the important equipment for high temperature heat treatment,vacuum sintering furnace has a wide range of applications.Furnace temperature uniformity and heating efficiency are the main indicators reflecting the heating performance of the vacuum sintering furnace,which are mainly determined by the heating rate and structural parameters of the heating system of the vacuum sintering furnace.Whether its design is reasonable directly affects the performance of the vacuum sintering furnace,the sintering quality of the workpiece and production efficiency.In this paper,the combination of numerical simulation and experimental verification is used to deeply explore the heating characteristics and system parameter optimization of the vacuum sintering furnace.Firstly,the basic heat transfer mode of the single-chamber batch vacuum sintering furnace is analyzed based on the relevant theory of heat transfer,and the 3D transient temperature field numerical model of the no-load single-chamber batch vacuum sintering furnace under constant heating rate is established by using ANSYS Fluent software.,and compared the simulation results with the measured temperature data,the maximum error is less than 10%,and an effective simulation model of the heating process of the vacuum sintering furnace is obtained.Secondly,on the basis of verifying the reliability of the simulation,the factors affecting the heating efficiency and furnace temperature uniformity of the single-chamber batch vacuum sintering furnace were further analyzed.An important parameter of temperature uniformity,changing the distance between the heating tube and the effective heating zone has little effect on the performance of the heating system;appropriately increasing the heating rate and the diameter of the heating tube can effectively improve the heating efficiency and furnace temperature uniformity of the heating system.A specific optimization plan is proposed: the heating rate is increased from the original 6K/min to 9K/min,the diameter of the graphite heating tube is increased from the original 35 mm to 45 mm,and the distance between the graphite heating tube and the effective heating zone is reduced from the original65 mm to 50 mm.After optimization,the heating time is reduced by 60 min,the heating efficiency is increased by 30%,and the maximum temperature difference between the vertex workpiece and the center workpiece surface is reduced from 10.85 K to 9.25 K,a decrease of14.7%.Thirdly,in view of the shortcomings of low production efficiency of single-chamber batch vacuum sintering furnace,the production process development and temperature field distribution of multi-chamber continuous vacuum sintering furnace were explored,and the multi-chamber continuous vacuum sintering furnace was established under no-load and load conditions.The three-dimensional transient temperature field simulation model based on the simulation model of the furnace is compared and analyzed,and it is concluded that the heating area near the graphite heating belt has a higher temperature,and the lower temperature is lower;the higher the set temperature of the heating belt,the more effective The greater the temperature difference in the heating area;when the length of the heating belt is0.28 m,0.31 m,0.34 m,0.37 m,and 0.40 m in turn,the maximum temperature difference in the effective heating area is 150 K,110K,90 K,80K,70 K,which increases with the length of the heating belt.When the moving speed of the workpiece is reduced from every 10 min to one feeding every 20 min,the maximum temperature difference inside the workpiece is reduced from 87.6K to 56.1K during the heating process,a decrease of 35.9%,and the temperature difference inside the workpiece increases with its moving speed.During the heat preservation period,the temperature difference of the workpiece decreases with the increase of the heat preservation time.The maximum temperature difference of the workpiece is reduced to within5 K when the temperature is kept at 573 K,873K,1173 K,1473k and 2573 k for 204 min,65min,28 min,12min and 98 min respectively,which meets the production process requirements of silicon carbide workpieces.This method can be used to calculate the holding time of each temperature zone.