Review: Thermal Debinding Process in Particulate Materials Processing

Abstract

Developing a rapid and efficient method for removing polymers (termed binders) from a shaped powder component, know as a green body, is important to forming defect-free metal, ceramic, and cermet structures. The rapid growth in powder injection molding to form complex shapes at high precision in large quantities has increased the need for faster, cleaner, and cheaper polymer removal processes. Binder removal using controlled heating of the component in gaseous atmosphere is the most popular method. This thermal debinding or burnout process is a delicate process, since it is easy to crack, blister, slump, or otherwise damage the component with an improperly designed cycle. To avoid these issues, often long heating cycles are used to remove the binder, but with a loss of productivity. Considerable progress has been made over the past several decades in understanding various phenomena during polymer burnout, resulting in substantial reduction in the thermal debinding time. This article provides an overview of the research carried out on thermal debinding process (primarily from powder injection molded samples) with major emphasis on progress reported over the last fifteen years. This review article proposes a model to predict the formation of defects during all stages of thermal debinding and suggests future research direction in the field.

Keywords:

• Bubble formation criteria
• Cracks
• Defects
• Distortion
• In situ strength
• Master decomposition curves
• Microstructure
• Microwave
• Modeling
• Residual carbon
• Stress and strains during thermal debinding
• Thermal debinding