A Finite Element Analysis for Improvement of Shaping Process of Complex-Shaped Large-Size Silicon Carbide Mirrors.

Ling Qiao,Jingchuan Zhu,Congcong Cui,Ge Zhang,Yingnan Wan

doi:10.3390/ma14154136

Abstract

In the gel-casting process, the proper selection of technological parameters is crucial for the final quality of a green body. In this work, the finite element method is used to investigate the mold characteristics in the gel-casting process, and the typical flow behaviors under different conditions are presented. Based on the distribution characteristics of temperature, pressure and flow field of gel polymer, the simulated results provide some possible reasons for the generation mechanisms of defects. Then, a series of simulations were performed to investigate the effect of process parameters on the molding quality of green gel-cast bodies. The results show that the decreasing loading speed can effectively reduce the number of defects and improve the molding quality. In addition, this paper presents a new technique by applying the exhaust hole to decrease the number of defects and, hence, improve structural integrity. The influence of the loading speed on the mold characteristics is well understood for the gating system with an exhaust hole, which suggests to us appropriate parameters for optimizing the molding design. This work provides a theoretical basis to explicate the generating mechanism of defects involved in the gel-casting process and acquires an optimized technique to produce a silicon carbide green body.

Highlights

Accepted: 5 July 2021Gel casting is a promising technology for manufacturing advanced structural ceramic bodies that have been invented in recent years [1,2]
The objective of this paper is to develop a gel-casting process for fabricating an SiC ceramic optical mirror and to examine the role of processing parameters with regard to the molding quality
After the ceramic particles and resin network fulfil the green body, it seems that the green body exhibits nearly uniform distribution on the surface

Summary

Introduction

Accepted: 5 July 2021Gel casting is a promising technology for manufacturing advanced structural ceramic bodies that have been invented in recent years [1,2]. Compared with the traditional ceramic forming processes, e.g., slip casting, tape casting and dry pressing, the potential advantages of gel casting include faster casting, favorable uniformity and high green body strength, which allows for fabricating of complex shapes and machining in green state [3,4]. As well as these preferred characteristics, gel casting avoids slumping during binder removal and enables the final green body with thin wall structures and high solid loading [5],which has successfully generated wide application in various materials, such as alumina, silicon nitride, silicon carbide. Despite empirical research focused on the preparation process and the corresponding optical properties, detailed information on Published: 25 July 2021

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