Germany-based metal processing company Bayerische Metallwerke GmbH, a subsidiary ofWolfram Industrie，已为钨合金开发并申请了新的材料生产过程。
该过程很特别，因为它能够以粉末形式产生高浓度的钨预抗合金混合物（Wnife和wnicu），从而使材料可用于3D打印和涂料工艺。在为期两年的开发阶段的支持下，该公司认为其新流程将为钨制成的更复杂的几何形状铺平道路，为诸如工具制造和3D印刷辐射屏蔽等应用程序提供了新的选择。
“The special feature of our tungsten-nickel-iron alloy is that we obtain it in the form of a pre-alloyed powder,” explains Dr. Hany Gobran, research and development manager at Bayerische Metallwerke. “This is suitable as a starting product for 3D printing and coating processes.”
Tungsten alloys: useful but stubborn
Tungsten alloys are well-known for their excellent corrosion resistance and high thermal conductivity, making them a perfect candidate for the chill-mold casting of aluminum parts. The heavy metal is also extremely dense, coming in at 19.3 g/cm³. With a density comparable to that of gold, tungsten sees extensive use in tool manufacturing and alpha and gamma radiation shielding in healthcare.
“Due to its resistance to corrosion and erosion from molten metals, as well as its excellent thermal conductivity, tungsten is the material of choice in the field of cast aluminium,” says Nabil Gdoura, research and development engineer at Bayerische Metallwerke. “The very high density in its pure form also makes it a good alternative to harmful lead, which is still used for radiation shielding in medicine, for example.”
Unfortunately, tungsten also has the highest melting point of all chemical elements (3,400°C) and a Mohs hardness of 7.5, rendering it extremely difficult to work with. As such, tungsten parts with more complex geometries such as curves and bores are often just made of hot-work tool steel instead, due to its ease-of-use and 3D printability.
Tungsten alloy production for 3D printing
According to Bayerische Metallwerke, all commercially available tungsten 3D printing alloys to date have been produced with relatively high concentrations of iron and nickel, often without any pre-alloying. Since the melting points of these metals are significantly lower than that of tungsten, high-temperature additive manufacturing processes such as powder bed fusion often result in their uncontrollable evaporation.
The new Bayerische Metallwerke process addresses this issue by pre-alloying the powder mix before processing. By combining all three elements as a multiphase material in each individual powder particle, the composition and distribution of the final alloy can be very closely controlled. As such, the metal can be processed at high temperatures without losing any of the iron, nickel, or copper.
The company states that its new process is capable of producing alloys with 80% – 98.5% (weight) tungsten, 0.1% – 15% nickel, and 0.1% – 10% iron and/or copper, depending on the desired application. With densities of 17 – 18.8 g/cm3, the alloy materials are more than suitable for tungsten’s conventional use cases in aluminum casting, tool manufacturing, and radiation shielding. As a bonus, the patented process also enables the flow behaviour and grain size of the powder particles to be determined.
“The higher the proportion of tungsten in the end product, the more resistant it is to molten aluminium and the better its thermal conductivity,” concludes Gobran. “If, on the other hand, good ductility and mechanical machinability play a greater role, the proportion of tungsten in the alloy can also be reduced accordingly. The composition can therefore always be adapted to the specific application and the respective complexity of the shape.”
Powder production for industrial additive manufacturing
Though it may be in the background, the powder production sector is absolutely crucial for the success of industrial additive manufacturing. Earlier this year,Pyrogenesis等离子体雾化技术专家，宣布成功测试其增材制造Nexgenpowder production line. Following a strategic decision to delay commercial production, the Montreal-based firm was able to implement improvements and hasnow tested for batch to batch consistencyin its production line.
在其他地方，加拿大采矿和金属公司Rio Tintorecently developed anew steel 3D printing powderusing water atomization technology. While it is widely believed that only high-cost gas and plasma atomizers are capable of producing industrial-grade powders, the company’s new steel powder has shown that water atomization is a more affordable route to 3D printing powder production.
Nominations for the2021 3D Printing Industry Awards现在开放，在谁领导该行业方面发表意见。
Subscribe to the3D打印行业newsletterfor the latest news in additive manufacturing. You can also stay connected by following us onTwitter, liking us onFacebook，然后调查3D打印行业YouTube频道.
Looking for a career in additive manufacturing? Visit3D Printing Jobsfor a selection of roles in the industry.
Featured image shows tungsten alloy powders produced by Bayerische Metallwerke. Photo via Bayerische Metallwerke.
