PSI atomisation technology optimises aluminium powder production for Additive Manufacturing

September 29, 2022

The PSI 120 Series HERMIGA atomiser (left) and aluminium parts additively manufactured from A20X powder (right) (Courtesy PSI)
The PSI 120 Series HERMIGA atomiser (left) and aluminium parts additively manufactured from A20X powder (right) (Courtesy PSI)

Phoenix Scientific Industries (PSI), Hailsham, East Sussex, UK, has reported growing demand for its advanced atomising systems used to process aluminium. Through its HERMIGA atomiser range, PSI provides customers ATEX-rated equipment to produce high quality spherical aluminium powders. Particle size distribution can be adjusted to suit the end user, achieving high yields – including at the finer end of the range for applications, such as Laser Beam Powder Bed Fusion (PBF-LB) Additive Manufacturing. The HERMIGA portfolio ranges from R&D to high-capacity production scale systems, and is offered in both batch- and continuous-pour modes. This is further complemented by PSI’s Powder Metallurgy development activities and post-production powder processing technology.

Aluminium is a low density, reactive metal with an affinity for oxygen, explains PSI. In the natural world it is found in the form of compounds, with bauxite (primarily aluminium oxide) being the most common raw material for the production of pure aluminium metal (an energy intensive process requiring electrolytic reduction). As a reactive metal, aluminium is both flammable and potentially combustible. Certain chemical reactions also release flammable gases (e.g., 2Al + 3H2O = Al203 + H2). Exposed to air, aluminium will readily form a stable oxide layer and, once coated, bulk parts are commonly used in many everyday applications.

In powder form, however, the risk factor increases due to increased surface area and the potential for combustion is widely recognised. The very properties that can pose production and handling challenges can also make aluminium powders very useful for a wide range of applications including thermal spray coatings, the production of paints, Additive Manufacturing, catalysts, solid propellants, fireworks and explosives among others.

Special aluminium alloys for Additive Manufacturing

The growth of Additive Manufacturing has promoted the development of new compositions particularly suited to the unique melting and solidification characteristics of laser and electron beam AM processes. Many of these alloys contain reactive elements – such as rare earths Ti and Zr – and require the clean vacuum/inert gas melting and atomisation techniques provided in PSI’s 120 Series HERMIGA production scale atomisers. One such atomiser has recently been installed at IRT M2P’s metal powder facility at Uckange, France. Installation faced certain challenges, explained PSI, with the larger of the atomiser components being installed through the roof to fit into an existing tall building with a restricted footprint.

A20X™ aluminium alloy

PSI reports that it also worked on developing A20X™ aluminium alloy for Additive Manufacturing. This alloy has particular good high-temperature strength due the dispersion-hardening effects of its TiB2 content, and was developed through the NATEP funded ‘High Strength Aluminium Powder for additive manufacture’ (HIGHSAP) project. The consortium brought together Aeromet (lead partner), PSI, Renishaw and Rolls Royce to optimise the A20X powder as produced by atomisation to achieve properties best suited to meet the AM production requirements for aerospace, defence and automotive applications. Using PSI produced powders, the consortium additively manufactured mechanical test specimens and components. Through the consortium’s combined expertise and capabilities, the following room temperature properties were achieved; ultimate strength of 511 MPa, yield strength of 440 MPa and elongation of 13% (elevated temperature testing was also conducted). AT20X powder is now commercially available.

The PSI fluidised bed platform (left) and powder being fluidised in transparent analogue retort for testing purposes (right) (Courtesy PSI)
The PSI fluidised bed platform (left) and powder being fluidised in transparent analogue retort for testing purposes (right) (Courtesy PSI)

Post processing by fluidised bed reactor

Over the past four years PSI has entered the field of fluidised bed technology. FBR’s are extremely versatile in the processing of powders, both metallic and otherwise. Applications include heat treatments, chemical reactions and coating via chemical vapour deposition (CVD) of powders in bulk which can be scaled to commercially attractive volumes. The mass and heat transfer characteristics of a fluidised bed make them especially suitable to processing at elevated temperature while pressure can be readily adjusted to optimise the output.

The ‘Establishing a UK-based Powder Supply Chain for Engineered Powders’ (ENGPOW) project used FBR technology to process powder with the final objective, being the on-site repair of damaged aluminium airframe components via coldspray deposition. Conventional welding repair cannot be used because this would adversely affect the temper of the substrate alloy in the heat affected zone (HAZ). Cold spray repair offers a substrate compatible alternative but is hampered by low deposition efficiency when spraying relevant aluminium grades. To solve the issue, the consortium developed custom heat treatments to soften the powder, resulting greater particle deformation and therefore bonding to the substrate. To achieve this, a PSI designed FBR platform was used to solution heat treat the powder followed by extraction, rapid quenching and cold storage at -40°C to prevent the onset of natural age hardening. The consortium was comprised of PSI (lead partner), TWI and Alphatek Hyperformance Coatings with BAE Systems in an advisory capacity. An FBR operated at PSI with containment vessel removed is pictured above, along with a low temperature analogue used to establish the fluidising characteristic of the aluminium powder before heat treating at elevated temperature is shown.

Aluminium – lithium alloy powders

PSI recently developed the technology for the manufacture of equimolar aluminium – lithium alloy powders. Due to the extremely low density of Li, 534 kg/m3, alloying such a high-volume fraction faced considerable difficulties compared to the more familiar structural versions containing up to 2.45% Li by mass. This combined with the high vapour pressure of Li presented difficulties during both alloying and subsequent powder handling. Revised passivation procedures had to be developed in the face of little reliable explosivity data and the tendency to react vigorously with water. A production plant has been installed at a customer’s site and is now in operation.

PSI will exhibit at this year’s Formnext exhibition, taking place in Frankfurt, Germany, November 15-18. The company will be located in Hall 12.0 – Booth B14.

www.psiltd.co.uk

About Metal Additive Manufacturing magazine

Metal AM magazine, published quarterly in digital and print formats, is read by a rapidly expanding international audience.

Our audience includes component manufacturers, end-users, materials and equipment suppliers, analysts, researchers and more.

In addition to providing extensive industry news coverage, Metal AM magazine is known for exclusive, in-depth articles and technical reports.

Our focus is the entire metal AM process from design to application.

Each issue is available as an easy-to-navigate digital edition and a high-quality print publication.

In the latest issue of Metal AM magazine

Download PDF
 

Extensive AM industry news coverage, as well as the following exclusive deep-dive articles:

  • Fly-by-wire: How Additive Manufacturing took to the skies with Norsk Titanium
  • Dynamic beam shaping: Unlocking productivity for cost-effective Laser Beam Powder Bed Fusion
  • Enabling the fusion energy revolution: Mastering tungsten with PBF-EB Additive Manufacturing
  • Patents and Additive Manufacturing: What insights can mining PBF-EB data reveal about the industry and the technology?
  • Additive Manufacturing for Semiconductor Capital Equipment: Unlocking critical supply chains
  • Can Additive Manufacturing lower the carbon footprint of parts for the energy and maritime industries?
  • Inspect Additive Manufacturing, stop monitoring: Phase3D’s unit-based, in-process inspection solution for powder bed AM

The world of metal AM to your inbox

Don't miss any new issue of Metal AM magazine, and get the latest industry news. Sign up to our twice weekly newsletter.

Sign up

Looking for AM machines, metal powders or part manufacturing services?

Discover suppliers of these and more in our comprehensive advertisers’ index and buyer’s guide, available in the back of Metal AM magazine.

  • AM machines
  • Process monitoring & calibration
  • Heat treatment & sintering
  • HIP systems & services
  • Pre- & post-processing technology
  • Powders, powder production and analysis
  • Part manufacturers
  • Consulting, training & market data
View online

Discover our magazine archive…

The free to access Metal Additive Manufacturing magazine archive offers unparalleled insight into the world of metal Additive Manufacturing from a commercial and technological perspective through:

  • Reports on visits to leading metal AM part manufacturers and industry suppliers
  • Articles on technology and application trends
  • Information on materials developments
  • Reviews of key technical presentations from the international conference circuit
  • International industry news

All past issues are available to download as free PDFs or view in your browser.

Browse the archive

Share via
Copy link
Powered by Social Snap