Alcan International Limited

Robert M Kimber

Prasad S Apte

Raymond Y Roy

David N Mitchell

Aniket Pant

Mark C Patterson

A method of heating a workpiece assembly and a load assembly suitable for heating by the method. The method involves heating the workpiece assembly in a microwave cavity surrounded by one or more rings made of electrically conductive material. The rings fix the electrical field in such a way that uniform heating of the workpiece assembly can be achieved. Large workpieces or assemblies can be heated and, if sinterable, sintered in this way without the problems normally caused by lack of uniform fields when microwaves are used to heat large loads.

Microwave heating of workpieces

A process for preparing a heat-treated body from a material (preferably a dielectric ceramic) that does not couple well with microwaves while nevertheless using microwave energy for the heating step. The process involves the use of a microwave susceptor (i.e. a material that couples well with microwaves) as a means for generating heat in the material. To avoid contamination of the final product, a susceptor is chosen which is converted, during the heating step, to a substance which is substantially the same as the material itself, both the susceptor and the material are converted to the same desired final product, or the material is converted to a substance substantially the same as the susceptor. The resulting substantially pure heat-treated (and preferably sintered) bodies can be used for a variety of purposes, e.g. as substrates for micro-electronic devices. The process can also be used for joining bodies of non-susceptor materials without contaminating the resulting joint.

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Sydenham, Canada

Robert M Kimber