Effect of pre and post heat treatments on microstructure and adhesion of AlTiN films deposited on additive manufactured Ti-6Al-4V alloy.

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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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In the introduction of this article, we’ve already discussed how different powder metallurgy technologies rely on vacuum furnaces for critical steps of their production process, mentioning Metal Injection Molding (MIM), Binder Jetting (BJT), Powder Bed Fusion (PBF) and Direct Energy Deposition (DED) additive manufacturing.

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From 5th to 8th September, TAV VACUUM FURNACES participated at the 27th IFHTSE Congress & European Conference on Heat Treatment 2022, held in Salzburg, Austria.

The International Federation for Heat Treatment and Surface Engineering is an institution linking organizations around the world active in the fields of heat treatment and surface engineering, including national metallurgical and heat treatment association, such as the AIM (Associazione Italiana di Metallurgia), for which TAV VACUUM FURNACES is a supporting member.

IFHTSE regularly organize international conferences and congresses to promote sharing of knowledge between associations, universities, research institutes and companies.
The IFHTSE – ECHT 2022 covered many different topics related to heat treatment of steels and non-ferrous alloys, thermochemical treatments, coating technologies and finally, furnace technology.

As one of the major vacuum furnaces manufacturer, TAV VACUUM FURNACES gave a speech during the first day of the congress about the heat treatment of titanium alloys, more specifically, on the “Vacuum heat treatment of Ti6Al4V alloy produced via SLM additive manufacturing”. 

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Sintered rare-earth permanent magnets (REPMs), more specifically Neodymium-Iron-Boron (NdFeB) and Samarium-Cobalt (SmCo) varieties, are foundational to numerous modern technologies due to their unmatched magnetic strength. Their applications are widespread, from consumer electronics and medical devices like MRI machines to critical green technologies such as high efficiency motors in electric vehicles and generators in wind turbines. However, the extraordinary performance of these magnets is not simply a result of their chemical composition. It is critically dependent on achieving a precise and optimized microstructure, which is primarily developed through a powder metallurgy process.

 

Figure 1: REPMs can be found in a variety of consumer products, high-tech devices and critical green technologies

 

This manufacturing route involves several high temperature stages, most notably sintering and multi-stage heat treatments. Within this process, vacuum furnaces are a pivotal technology. They provide the stringently controlled atmospheric conditions essential for densification and for developing the specific microstructural features that give these advanced materials their exceptional magnetic properties. In this article, we will explore the critical functions of vacuum furnaces in the sintering and heat treatment of high performance NdFeB and SmCo magnets.

Powder metallurgy route for REPMs

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