Engineering, Equipment & Technology, Powder Handling

Titanium and tantalum powders for 3D printing and tech sector

Metalysis, a small metal producing company based in Sheffield in the UK, is commercialising an electrolysis technology which it believes will re-write the economics of tantalum and titanium powder production. ABHR’s Charles Macdonald spoke to Metalysis’ business development manager, Mr Kartik Rao.

3D printing is on a roll. Growing at around 30% a year, the technique uses lasers or electron beams to build a part layer by layer. Dubbed additive manufacturing, it contrasts with traditional subtractive manufacturing which mills down a block of metal. The new technique is being embraced by industries like aerospace and medical devices which see scope to build parts such as turbines and hip sockets that are lighter and stronger.

3D printers use as their fuel metal powders which are selectively melted to grow a part. However, titanium powder, to date produced by an energy intensive, 70-year old technique called the Kroll process, doesn’t come cheap.

This is where Metalysis comes in. Its patented process, first conceived by researchers at Cambridge University in 1997, produces titanium powder directly from rutile using electrolysis in one step.

“The ink for 3D printing, if you like, is really metal powders,” explained Kartik Rao. “Right now, the cost of the material, the cost of the powders is a significant proportion of the overall cost of producing a part. With time, the end users are hoping that the cost of the powder goes down.

“We are developing our process so that we can actually produce powders which are lower cost and enable the market to grow much more rapidly.”

Metalysis' scientist Nader Khan in the R&D cell room.
Metalysis’ scientist Nader Khan in the R&D cell room.


Besides titanium powder, Metalysis is also playing in the far smaller but more immediately lucrative market for tantalum powders. These are used in the ever-smaller capacitors which underpin technologies like the smart phone and tablet.

Cambridge University ‘lightbulb moment’

Metalysis’ genesis goes back to 1997 with three metallurgists at Cambridge University – Derek Fray, Tom Farthing and George Chen – working on a project to re-generate titanium turbine blades used in jet engines.

The turbine blades, after several years of service, get a coating of oxide that is detrimental to performance and of major concern to airlines.

“They tried to remove this by putting in a molten salt and subjecting it to an electric current,” said Rao. “They discovered the surface oxide had been converted into metal. They then took this one step further and said ‘what happens if we put in bulk metal oxide powders?’ They realised this process could convert metal oxide powders into metal powders just by stripping the oxygen out.

“It was a wonderful moment of discovery, a lightbulb moment at Cambridge.”

It was at that stage that the University’s technology and licencing arm began to work out how to capitalise on the technology. One method was to spin-out Metalysis as a company in 2002 to exploit what is now known as the FFC process after Fray, Farthing and Chen.

“We had all the rights to exploit the process across the periodic table because it works for so many elements,” stated Rao. “We received some initial seed funding from the University. That allowed the company to develop a proof of concept and get funding from venture capital and we haven’t looked back since.”


Milestones in Metalysis’ 13 year life

Metalysis has assembled a formidable body of intellectual property with 25 live, published families of patents in place. In addition to those around Cambridge University’s FFC process, the company has acquired more along the way.

“We also acquired intellectual property from other companies,” recounted Rao. “One was QinetiQ, an arm of the UK Ministry of Defence, in 2005. We acquired the intellectual property to another process, very similar to our own, developed by BHP Billiton. We got that in 2006.”

BHP Billiton remains a shareholder. Another miner to back the company, but in a far more substantial way, is mineral sands miner Iluka Resources, which emerged with a share of just over 18% in 2014.

“They invested US$20m in Metalysis as a strategic investment because we are capable of taking their product, a mineral sand, and converting it directly into a titanium powder which is vastly more expensive in the market. It’s a real value adding step.”

In 2015, Metalysis has partnered with GKN, a major international supplier of parts to the aerospace and automotive sectors. “They’re looking into the use of our titanium powders for 3D printing,” said Rao.

Metalysis’ executive ranks have been strengthened over the years with seasoned executives. Chief executive Dion Vaughan, for example, combines metals experience at Sheffield Forgemasters and Johnson Matthey with financial exposure at Hatch Corporate Finance and JP Morgan.

(l to r) Douglas Caster, Metalysis chairman; Ian Mellor, technology director; and Tony Ratcliffe, chief financial officer.
(l to r) Douglas Caster, Metalysis chairman; Ian Mellor, technology director; and Tony Ratcliffe, chief financial officer.


The firm now employs around 60 people in Sheffield, a city which was at the heart of the industrial revolution and which retains a strong metals and engineering constituency.

Assets-wise, Metalysis has equipment that functions on three scales. There is research equipment capable of producing grams of material at a time. A development capability produces kilos and tens of kilos. Finally, a small industrial unit, which is a prototype production plant, is capable of tonnes of material per year. This machine is deployed now on tantalum production.

Rao said that “In the last few weeks we’ve completed over 30 runs in the tantalum production unit which is a key milestone for us because it allows us to use metal powders at a commercial scale at our current facility. This production plant that we’ve had running now for nearly two quarters represents the first new tantalum production facility in Europe in over 30 years.”


Tantalum first cab off the rank

Metalysis has prioritised commercial tantalum powder production over that of titanium powder for various reasons.

Firstly, while titanium powders sell for between US$200 and US$400 per kilo, tantalum powders come in at between US$500 and US$2,000 per kilo.

In addition, the size of the market for tantalum, versus that for titanium is much smaller.

“At 2,000 tonnes per year, it’s a size of market we can get our arms around as a small company,” said Rao. “This is something we can do ourselves and start to service our customers globally. We have customers in the electronics, biomedical and the aerospace industries for tantalum powders.”

In addition, early production from Metalysis’ small plant sends a strong signal to customers.

“It allows us to benchmark our technology but also to validate its scalability,” Rao said. “This is an incredibly powerful message for future partners. ‘You may be interested to see a working plant that is capable of producing metal at a commercial scale’.”

50% of tantalum produced nowadays ends up in small electronic components called capacitors, essential parts of the circuitry of iphones, ipads and laptops. The functional benefit of tantalum powders has been in allowing ever greater miniaturisation of capacitors and hence the devices they go into.

Tantalum’s other uses include as an additive in super alloys, and as an anti-corrosion coating used by chemical engineers for critical components in industries like nuclear power.


Making titanium competitive with stainless steel

Out of the seven million tonnes of titanium minerals mined every year globally, less than 5% ends up as metal. Most ends up in paints, plastics and food additives.

The 5% that ends up as metal is normally converted by a process called the Kroll process which is 70 years old now. It was developed to produce titanium during the early days of the Cold War for spy planes and for high end aerospace components.

As a metal, it’s exceptionally light, strong and corrosion resistant but the continuing use of the Kroll process, involving multiple steps and hazardous chemicals, has added to production costs and restricted the use of titanium to really specialist industries like aerospace which can afford to pay for the metal’s unique properties.

Metalysis hopes that use of the FFC process, which has the potential to operate continuously, can drop the price of titanium and shift the perception of it from quasi precious metal to mass market metal.

Using the Metalysis process, the price of titanium, which now costs about five times more than stainless steel, could fall significantly to the extent that titanium produced by the FFC process can compete in the performance alloy market (worth US$4.4bn annually) and stainless steel market (worth US$110bn annually).

In addition, Metalysis, like its competitors, is reaching out to participants in the burgeoning market for 3D printing, with titanium powder increasingly used as feedstock for additive manufacturing.


Economics of process a secret

“Economics of our process are a closely guarded secret but we absolutely have a cost benefit,” asserted Rao. “We operate at a lower temperature than many conventional processes.

“For instance, we don’t melt our metal. To melt tantalum you have to go up to 3,0000C and to melt titanium 1,7000C. Our process operates at between 800 and 9000C. So there’s an energy saving.

“We use electricity to directly reduce metal powders so that has an energy saving. Our process is very similar to a conventional aluminium smelting process.”


Bulk handling aspects

Metalysis’ feedstock can be bulk conveyed in the open air and doesn’t need any special handling.

“The metal powder we have to take much more care with because there are certain health and safety risks associated with it,” said Rao. “We try and convey slurries instead of solids. It’s only at the very final stages that we end up with dry powder when we bag it.”


How the FFC process works

A metal oxide, such as titanium dioxide, is delivered to the processing site in powder form. The metal oxide powder is processed into a powder feed so that the right powder sizes and alloying contents can be achieved in the metal powder.

These are then placed into a crucible (reduction vessel) containing the molten salt (usually calcium chloride) which is held at between 8000C and 1,0000C.

The reduction vessel is kept in an argon-rich atmosphere to avoid re-oxidisation of the product. The metal oxide then forms the cathode in the reduction vessel.

When an electric current is passed between the cathode (negative electrode) and a carbon anode (positive electrode) the oxygen is removed from the metal oxide. The oxygen passes through salt and reacts with the carbon anode to form carbon dioxide and carbon monoxide. These gasses bubble off leaving the pure metal on the cathode. The pure metal is in a powder form after the oxygen atoms are removed.

Any remaining impurities, such as salts, are washed out. It is then dried and ready for use. Since the process operates in the solid state it is ideal for producing alloys using combinations of elements possessing dissimilar melting points, not possible by conventional means.


Tough competition in powder metallurgy

Metalysis is up against some deep-pocketed competitors in the powder metallurgy space.

US/German company HC Starck was founded in 1920 and is a major manufacturer of customer-specific powders and components made from technology metals and technical ceramics.

The company employs around 2,600 staff with 140 working in research and development. It holds over 900 patents worldwide, having filed its first patents for tantalum and niobium powders as far back as 1945.

HC Starck’s recent financial report said that its R&D people were focussing on: “Research and development focused on projects to increase the yield in processing secondary materials and byproducts, to continuously improve the quality of high-capacity tantalum and niobium powders, and to develop special tungsten carbides for the Asian market.

“In addition, HC Starck launched several partnerships to use tantalum pastes in manufacturing ultra-thin capacitors with heights less than 0.3 millimeters. These capacitors can be used to make very thin electronic devices that will be used in many forward-looking trends, for instance wearable electronics.

“Another research focus was on developing high-purity tantalum and niobium oxides, which are the base material for SAW filters. Among other things, these are used in mobile phones and are essential for secure signal processing during data transfers, an area that is growing rapidly thanks to increasing mobile phone and internet usage.

“Additionally, HC Starck signed a development contract with Rapid Prototype and Manufacturing (rp+m), a US company specialising in 3D printing technologies. The contract includes developing innovative products from technology metals that are manufactured using 3D printing processes, also known as additive manufacturing.”

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