Optimization of microwave-assisted rapid debinding of CIM parts in multimode applications

Microwave (MW) heating selectivity was exploited in this work for the rapid thermal debinding of parts obtained by Ceramic Injection Moulding (CIM). Since the organic binder preferentially absorbs microwaves with respect to ceramic powders, heat can be efficiently transferred to the green parts, despite their low thermal conductivity which renders conventional heating techniques less effective. However, one of the major drawbacks of microwave-assisted processes is the lack of reproducibility of the results, and of non-adequate experimental conditions and procedures which can lead to misleading conclusions on the effective yield of the process. A rational approach to overcome this problem, consisting in numerical simulation coupled to Design of Experiments (DoE) technique was used. In this way it has been possible to optimize the MW-assisted thermal debinding of ring-shaped CIM parts in multi-mode applicators operating at 2.45 GHz, reducing processing times from the original 80-140 hours (depending on the shape and dimensions of the samples) by conventional heating to 6 hours by dielectric heating.