Theory and practice of rapid and safe thermal debinding in ceramic injection molding

Abstract

In this paper, the dynamic process of thermal debinding was analyzed. The critical thickness of debinding was defined as the thickness at which the steps to control dynamics change from diffusion of gas products in liquid binder to diffusion or permeation in pores. Subsequently, the equation of critical thickness was deduced. The results show that the critical thickness of debinding is independent of the thickness of the green body, but mainly depends on the particle size, solid content, and binder composition. Moreover, larger particle diameter and higher solid loading will contribute to a greater critical thickness, which means that higher heating rate can be used in the initial stage of debinding. The prediction is in agreement with the experimental results. In addition, the effect of binder composition on the formation of cracks during thermal debinding was investigated by thermogravimetry combined with FTIR spectrometry (TG-FTIR) analysis of binders and thermogravimetric curves of feedstocks. It suggests that the feedstock containing polystyrene and acrylic resin is helpful for rapid and safe thermal debinding. K E Y W O R D Sbinders/binding, ceramic engineering, defects, thermal debinding | 1099 XIE Et al.

Influence of the Infill Orientation on the Properties of Zirconia Parts Produced by Fused Filament Fabrication

“…In both cases, two decomposition ramps can be observed, a ramp at low temperatures with a pronounced mass loss, and a ramp at higher temperatures with a lower mass loss rate. Each ramp corresponds to the progressive degradation of the polymers in the multicomponent binder system, as has been already observed for zirconia feedstocks for ceramic injection molding [ 50 ]. From Figure 5 , it can be seen that the slope of all the ramps is more pronounced and the degradation starts at lower temperatures for the feedstock than for the binder.…”

Effect of Thermal Debinding Conditions on the Sintered Density of Low-Pressure Powder Injection Molded Iron Parts

“…The TGA results confirmed that the chemical nature of the powder could change the kinetic of binder decomposition. Xie et al [30] used TGA coupled with FTIR spectrometry (TG-FTIR analysis) to quantitatively study and design the thermal debinding cycle for HPIM zirconia-based feedstocks and evaluate the effect of binder composition, decomposition rate, degradation temperature range, and products on the quality of debound parts. W.-K. You et al [31] used the TGA approach to design a thermal wick debinding cycle adapted to spherical iron-based feedstocks (i.e., to blends of micrometric and nanometric powders).…”