Minimum Amount of Binder Removal Required during Solvent Debinding of Powder-Injection-Molded Compacts

Abstract

Unsatisfactory dimensional control, distortion, and defects are frequently observed in powderinjection-molded parts, particularly after the solvent and thermal-debinding processing steps. One of the reasons is that the amount of soluble binder removed during the first step, solvent debinding, is not great enough to form interconnected pores throughout the compact, particularly in the core region. Thus, blistering, cracking, and bubbles can form easily during the subsequent thermal debinding. To determine the minimum debinding fraction required for solvent debinding, at which point interconnected pore channels are formed at the center, modeling of the distribution of the remaining soluble binder in the compact was established. The actual distribution, which was obtained by measuring the binder content layer by layer with the soxhelt extraction method, is in good agreement with the model. The modeling, bubble test, and fluorescence dye-penetration analysis show that, regardless of the compact thickness, the minimum bulk debinding fraction needed is consistently approximately 59 pct, yielding a local debinding fraction of 37 pct and a porosity of 8.5 pct at the center. This porosity is close to the value at which pores in a sintered compact transform from open to closed at the beginning of the final stage of sintering.

Water‐Soluble Binder System Based on Poly‐Methyl Methacrylate and Poly‐Ethylene Glycol for Injection Molding of Large‐Sized Ceramic Parts

“…When more than 40% of total binder (equivalent to 65% of PEG in this research, shown by the line in the Fig. ) was leached, the connected pore nets were created in the compacts . At this stage, the green body could be moved to the second step of rapid thermal debinding.…”

“…8) was leached, the connected pore nets were created in the compacts. 31,32 At this stage, the green body could be moved to the second step of rapid thermal debinding. As connected pore nets formed, gas from thermal degradation of the rest binder could escape from these pore nets easily without cracking or blistering.…”

Impact of Polymer Binders on the Structure of Highly Filled Zirconia Feedstocks

“…As the mass loss of every sample was at least 96 wt% of the wax weight introduced in the blends, we concluded that wax network was highly continuous in the whole sample. Its extraction created an open-pores network characteristic of the sample structure [ 20 ]. The latter reflects binder–binder and particle–binder interactions developed in each blend and can be characterized by porosimetry.…”

The investigation of the effects of debinding time and dimensions of sample on parts produced from tungsten carbide by powder injection molding

“…Literatürde de parça kalınlığındaki artışının kimyasal bağlayıcı ayrıştırma süresini arttırdığı belirtilmiştir. Fan ve arkadaşları çalışmalarında numune kalınlığının 2 mm den 8 mm ye çıkması bağlayıcı ayırma süresini 0,8 saatten 12,9 saate çıkardığı tespit etmişlerdir [20]. Ayrıca Oliveira ve Chen çalışmalarında parça kalınlığının bağlayıcı ayırma sürecinde ağırlık kaybına etkisinin olduğunu tespit etmişlerdir.…”