# The Pin Structure Design of LaVai-1.5-1400 Microwave Vertical Tubular Furnace Based on COMSOL
## 1 Introduction  
Microwave heating is a technology of great interest to various industries and research groups. Microwaves exist as a form of energy, but can be converted to heat when entering some materials. Materials generally exhibit the following four properties for microwaves: absorption, partial absorption, penetration, and reflection. In the field of microwave processing, the materials we process are generally microwave-absorbing medium materials, which can be coupled with the microwave electromagnetic field, and then use a variety of different ways of power dissipation to ultimately achieve the goal of converting microwave energy into heat. Researchers have studied the effects of microwave heating on the microwave-sintering process of ceramics [1], metals [2], and composites [3], which are also widely used in microwave joining [4], microwave melting [5], microwave cladding [6], and polymer processing [7]. Microwave heating has many advantages over traditional heating methods: it is more energy efficient, more efficient, and more effective [8; 9]. Due to the variety of ceramics to be heated, the complexity of the microwave heating mechanism, and the imperfect test conditions, the experimental cost is expensive and other reasons, many scholars by means of simulation to study and analyze the microwave heating process of the material. Microwave heating consists of several physical phenomena coupled together, which mainly include the processes of electromagnetic loss and heat conduction, and both of these phenomena must be taken into account in the simulation of microwave heating. For the simulation of microwave heating process, [PERSON] et al. [10] simulated sintering experiments in a multimode microwave cavity using the finite difference method. [PERSON] et al. [11] developed a simulation model for heating food in a microwave oven. [PERSON] et al. [12] proposed and tested a simple semi-analytical model based on the approximation of segmentation constants for material properties. [PERSON] et al. [13] compared the temperature distributions of cylindrical samples heated in a microwave oven with those realized in a radiantly heated conventional oven. [PERSON] et al. [14] confirmed that the heating ofSiC depends only on the electric field, emphasizing and analyzing the effect of the sample orientation, and the length of the cavity on the heating. [PERSON] et al. [15] questioned why the use of pedestals aided microwaves in most of the experimental work heating and investigated this issue experimentally and through numerical simulations. [PERSON] et al. [16] described mathematical models and numerical methods for simulating complex sintering processes, integrating the densification process of powdered materials into the original microwave heating model, allowing the model to further predict parameters such as material shrinkage. [PERSON] [17] simulated the heating of the SiC base to understand its role in the microwave heating process and analyzed the effect of different microwave powers and SiC sizes on the heating of the sample. [PERSON] et al. [18] further analyzed the effect of mold design assembly and microwave power parameters on the temperature distribution and electric field distribution of bulk metal specimens. In high-power microwave heating cavity models, the distribution of the electromagnetic field within the resonant cavity can be affected by artificially loaded or altered dielectrics. At the same time, the resonant state of the resonant cavity may also change. To adjust the electromagnetic field distribution within the resonant cavity, enhance the microwave coupling of Al\({}_{2}\)O\({}_{3}\)/SiC composite materials, and restore the original resonant state of the resonant cavity as much as possible, pins are introduced to create artificial disturbances.