The following points must be observed during debinding
The heat treatment must be carried out slowly during thermal debinding, as pressure can be generated in the component due to the decomposition of the binder and the associated steam generation. A sufficient amount of oxygen or air should also be supplied to enable binder removal. Special precautions must be taken when debinding large products or products with high binder content (e.g. products produced by injection moulding, extrusion, slip casting or other plastic forming methods). In some cases, debinding is performed in a separate low-temperature furnace followed by firing in a high-temperature furnace. The maximum heating rate is determined by the product size and shape. High heating rates can cause a temperature gradient in the product, which leads to uneven shrinkage in the inner layers of the product. This can lead to cracking.
Temperature homogeneity, as well as a constant and homogeneous air or oxygen flow within the furnace during each debinding process, is also of great importance to avoid temperature gradients in the product. Temperature and air flow should, therefore, be set, measured and controlled very carefully. It is also very important to continue heating after debinding and to sinter the products before transport. Ceramic products are very brittle and sensitive to mechanical stress in the phase between debinding and sintering. Transporting the goods before sintering may, therefore, lead to cracking or major damage.
The waste gases produced during debinding contain hazardous organic materials and must be carefully extracted from the furnace and treated in a separate chamber in accordance with the relevant safety and environmental regulations. In practice, binder systems consist of a mixture of at least two components that differ in volatility and chemical decomposition. This makes it even more complicated to control the process of debinding.
Concise Encyclopedia of Advanced Ceramic Materials, ed. by R.J. Brook, Pergamon, 1991, Oxford
M.N. Rahaman, "Ceramic Processing and Sintering" 2nd edition, CRC Press, 2003, New York