Presently, such methods are used in drying, removing binding agents and sintering very large ceramic components in an industrial production scale. The advantages of this method lie with the clearly lower energy consumption, the more homogeneous heating (lower temperature gradient) and reduced densification times. This results in an economic production process.
These methods are still critical for oxide ceramics such as Al2O3 and ZrO2 in that no effective electromagnetic dissipation occurs at ambient temperature. Until today, this obstacle was obviated using a conventional heating, since the effectiveness of the dissipative coupling of the super high frequency waves increases drastically from a certain temperature. However, this increases the time and energy input so that the above mentioned advantages of this technology are greatly relativized. Avoiding the conventional heating can be achieved by adding suitable materials that show significant polarization losses already at ambient temperature, or by suitable sintering additives. This method has disadvantages in the reduced mechanical properties of the cooling ceramics as compared to the pure material. They are especially unsuitable for use in prosthetic medical products for aesthetic and biocompatibility reasons.
Moreover, the question of insulating material for thermal insulation of the baking chamber from the environment is still unanswered for large scale industry purposes. The difficulty lies with the low thermal conductivity and the simultaneous high transparency to super high frequency waves
The technical problem the invention is based on was to provide a method, and a vessel for performing this method, which would allow to use microwave treatment also other fields than in large scale industry, especially in the field of dental ceramics.