Design Of Annealing Furnace With Adjustable Atmosphere And Magnetic Field For Treatment Of Absorbing Materials

With the improvement of radar detectability, the application technology of radar absorbing materials has become a research focus. The properties of absorber are mainly determined by the electromagnetic parameters of material and its frequency spectrum characteristics. Based on the principle how vacuum and magnetic-field annealing influences the microwave electromagnetic properties of absorber, the design scheme of furnace for atmosphere and magnetic-field annealing was proposed and achieved. Feasibility of improving the properties of absorber by treatment was also verified.The design principle of furnace for atmosphere and magnetic-field annealing was explained, including the design of furnace architecture, temperature-control system and magnetic-field generator. Samples can be heated evenly in the flat-temperature zone of furnace chamber, and the surface temperature of furnace was less than 60℃. The port of furnace tube was sealed under the condition of low temperature and normal pressure. The nitrogen atmosphere of furnace chamber was achieved by vacuum-pumping and nitrogen-inflating. The flow of the nitrogen can be observed by means of drainage. The design of temperature-control system was based on PID control principle. The controller analyzed input temperature signal, provided control signal for thyristor module, and thus controlled the power of heating wires. Test results showed that the temperature curve coincided with theory curve approximately, the accuracy of temperature control was±5℃, the length of flat-temperature zone was about 12cm, and the temperature gradient in axial direction was less than 5℃. The design of magnetic-field generator was based on the model of electric solenoid. Design parameters were chosen through simulation and optimization. The magnetic-field attenuation in axial direction was determined through quantitative analysis. The current of electric solenoid was provided by power system which consisted of contact transformer and rectifier filter module. The regulating range of magnetic-field intensity was 0～400Oe. Oil cooling equipment acted as the radiator of electric solenoid.The design scheme of furnace for atmosphere and magnetic-field annealing was verified through tests and simulations. The expected performace index was achieved.