Refractory metals - powder for additive manufacturing

Refractory metals in additive manufacturing – high-performance components under extreme temperature conditions

Refractory Metals

Refractory metals are particularly resistant, extremely high-melting-point technology metals. Their high melting point, low thermal expansion and high strength and hardness make them suitable for high-technology applications, such as for crucibles in smelting metallurgy or components in furnace construction. They are also used in power electronics, where they are preferred for their high thermal and electrical conductivity.

Refractory Metals

However, these properties also make all refractory metals difficult to process mechanically. The solution: layered production in an additive manufacturing process.

Producing refractory metal powders for additive manufacturing is challenging because of the high temperatures required. As a result, only a few companies are able to do this. Heraeus has been working with refractory metals since the 1930s. In a high-temperature EIGA facility developed especially for us, we produce refractory metal powders with improved fluidity and high powder density while achieving a high degree of purity for our customer-specific applications.

Heraeus offers powders made of tungsten, molybdenum, niobium and tantalum as well as their alloys, which are optimized for additive manufacturing with refractory metals.

Tungsten is the best-known refractory metal because of its unsurpassed heat resistance. At 3,422°C, its melting point is the highest of all metals. Tungsten is used especially in the lighting and illuminant industry, in high-voltage electrical lines and, because of its high density (19.3g/cm3), for radiation shielding and as a balance weight in medical analyzers and x-ray examination devices.

Molybdenum is very similar to tungsten, but lighter, and its lower hardness makes it easier to process. Its melting point is 2,620°C. This refractory metal is preferred for the production of aircraft and rocket parts and is also used in furnace construction.

Tantalum and niobium stand out particularly for their excellent resistance to oxidation and chemicals. Because of their good biocompatibility, they are often used in the medical and optical field for the production of implants or medical instruments. Tantalum is particularly preferred for high-performance capacitors in microelectronics, while niobium is chosen for superconductive cables and magnets because of its high transition temperature.

We manufacture and process the powder and perform 3D printing. Please contact us to discuss potential collaboration.

In the additive manufacturing of a large tungsten component (height 295 mm), both our printer and the water cooling system meet their limits. While temperatures greater than 1,000°C must be maintained on the building panel, the mechanical and electronic components of the printer must also be cooled down at the same time.

Given the high density of tungsten, the two filled powder hoppers of the printer weigh approximately 340 kilograms. This is too much weight for many laser-based printers. Therefore, Heraeus used an electron-beam-based printer to print this component.

Because working with the electron beam causes the emission of x-rays, Shielding measures are especially important when printing with tungsten. To ensure that the resulting x-rays are fully contained, we work closely with the printer manufacturer and conduct a variety of tests.