In the first part of the article we discussed about powders and the classifications adopted for cemented carbide, as well as the importance of using a proper dewaxing cycle.

In this second part we will go more in depth about the sintering process, discussing the difference between vacuum sintering and sinter-HIP for cemented carbide and the equipment.

Sintering

Vacuum furnaces can be designed to carry out both thermal dewaxing and sintering on the same piece of equipment. In that case, furnaces are equipped with a wax trapping system and a box with calibrated gas nozzles for an homogeneous gas flow distribution. The gas flow distribution is critical to efficiently remove wax vapors from the parts and ensure an optimal temperature uniformity.

TAV VACUUM FURNACES HM Series - Sinter-HIP furnace equipped for hydrogen overpressure operation. 
The electrically fired H2 burner is visible on top of the furnace.

However, separated dewaxing furnaces are sometimes used to improve productivity and cleanliness on the sintering furnace. In the that case, even if dewaxing is generally completed at temperatures below 500°C, parts are heated to higher temperatures approaching 1000°C as a pre-sintering step, to ensure sufficient strength on the parts to be moved to the sintering furnace.

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