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Science & Innovation

2019 has been declared by UNESCO as the Year of the Periodic Table. To celebrate, we are releasing a series of blogs about our favourite elements and their importance to the chemical industry. Today’s blog focuses on tungsten.

History

Over three centuries ago, this metal was first used by porcelain makers in China. They used a tungsten pigment to incorporate a peach colour into their art work. In 1781, Wilhelm Scheele examined a metal containing tungsten and successfully isolated an acidic white oxide, deducing the oxide of the new metal. In 1783, Wilhelm’s brothers produced the same acidic metal oxide, and upon heating it with carbon, they successfully reduced it to tungsten.

 tungsten

Health concerns

Tungsten raises concerns regarding the health effects associated with its levels of toxicity. Initially, tungsten was perceived to be immobile in the environment and therefore used as a viable replacement for lead and uranium in military applications. However, reports showed traces of tungsten detected in soil and potable water sources, increasing the risk to human exposure. According to public health reports, it is unlikely that tungsten present in consumer products poses a hazard or causes any long-term health effects. Therefore, further assessment on the potential long-term health effects of tungsten exposure is still required.

 tungsten pot

Properties

Tungsten is a refractory metal and as it has the highest melting temperature of all metals, it is used across a range of applications. Tungsten is alloyed with other metals to strengthen them. This makes them useful to many high-temperature applications, including arc-welding electrodes.

 hazard assessment form

Properties

Tungsten is a refractory metal and as it has the highest melting temperature of all metals, it is used across a range of applications. Tungsten is alloyed with other metals to strengthen them. This makes them useful to many high-temperature applications, including arc-welding electrodes.

the simpsons gif - heat wave causes ink to fall off newspaper

Originally posted by everythingstarstuff

It is used as a novel material for glass parts due to its superior thermochemical stability. As it is a good electric conductor, it is also used in solar energy devices. Tungsten compounds act as catalysts for energy converting reactions, leading many manufacturers to investigate further uses of tungsten.


Science & Innovation

 Concorde

The Concorde was the first commercial supersonic aircraft to have been built. Image: Wikimedia Commons

In 2011, a chance encounter under the wings of Concorde at Duxford Air Museum, Cambridge, with Trinity College Dublin Professor Johnny Coleman, would set in motion a series of events that would lead, six years later, to the development of a 20t/year graphene manufacturing plant.

As soon as we got talking, I was impressed by Johnny’s practical, non-nonsense approach to solving the scalability issue with graphene production.

Coleman is a physicist, not a chemist, and believed that the solution lay in mechanical techniques. Following the conference, Thomas Swan agreed to fund his group for four years to develop a scalable process for the manufacture of graphene.

 graphene

Just a nanometer thick, graphene consists of a single layer of carbon atoms joined in a hexagonal lattice. Image: Pixabay

Coleman and his team initially considered sonication – when sound waves are applied to a sample to agitate its particles – but quickly ruled it out due to its lack of scalability. He then sent one of his researchers out to the shops to buy a kitchen blender. They threw together some graphite, water, and a squirt of washing-up liquid into the blender, switched it on, and went for a cup of coffee.

When they later analysed the ‘grey soup’ they had created, they found they had successfully made few-layer graphene platelets. The group then spent months optimising the technique and worked closely with Thomas Swan scientists to transfer the process back to Thomas Swan’s manufacturing HQ in Consett, Ireland.

spongebob gif

Originally posted by spongebob-squarepants-is-my-hero

Graphene is 300 times stronger than steel.

The plant can make up to 20t/year of high quality graphene. It uses a high sheer continuous process to exfoliate graphite flakes into few-layer graphene platelets in an aqueous dispersion.

The dispersion is stabilised by adding various surfactants before separating out the graphene using continuous cross-flow filtration devices developed with the support of the UK’s Centre for Process Innovation (CPI), part of the High Value Manufacturing Catapult – a government initiative focused on fostering innovation and economic growth in specific research areas.

 sticky tape

 

Using sticky tape, scientists pulled off graphene sheets from a block of graphite. Image: Pixabay

This de-risking of process development using a Catapult is a classic example of effective government intervention to support innovative SMEs. CPI not only showed us it worked, but also optimised the technique for us.

The company quickly realised that selling graphene in a powder form with no application data was not going to work. Instead, we developed a range of performance data to assist the sales team by highlighting what graphene can do if adopted into a range of applications.

 

The potential of graphene can be commercialised using composites. Video: The University of Manchester – The home of graphene

We also moved to make the product available in ‘industry friendly’ forms such as epoxy resin dispersions or polymer masterbatches. This move, slightly downstream from the raw material, has recently led to Thomas Swan announcing its intention to expand its range of formulated graphene materials, with a prototype product focusing on the manufacture of a carbon fibre composite.

Our application data shows that graphene has significant benefits as an industrial additive. Presenting this data to composite-using downstream customers is starting to open doors and create supply chain partnerships to get a raw material all the way to a fully integrated application.

 2010 Nobel Prize in Physics

Andre Geim and Kostya Novoselov won the 2010 Nobel Prize in Physics for their discovery of graphene. Image: Wikimedia Commons

The move downstream, to develop useable forms of graphene, is common in the industry, with most graphene suppliers now making their products available as an ink, dispersion or masterbatch. Thomas Swan’s experience with single-wall carbon nanotubes has made us aware of the need to take more control of graphene application development to ensure rapid market adoption.

Graphene applications drawing most interest include composites, conductive inks, battery materials, and resistive heating panels, although much of this demand is to satisfy commercial R&D rather than full commercial production.

Graphene science | Mikael Fogelström | TEDxGöteborg. Video: TEDx Talks

Thanks to innovations like our continuous high sheer manufacturing process, Thomas Swan believes that graphene is about to become very easy to make. Before it can be considered a commodity, however, it will also need to deliver real value in downstream applications. Therefore, the company is also increasing its efforts to understand market driven demand and application development.

As the initial hype over the ‘wonder’ material graphene starts to wane, progress is being made to develop scalable manufacturing techniques and to ensure graphene delivers some much-promised benefits to downstream applications.

Energy

Determining the efficacy of organic solar cell mixtures is a time-consuming and tired practice, relying on post-manufacturing analysis to find the most effective combination of materials.

Now, an international group of researchers – from North Carolina State University in the US and Hong Kong University of Science and Technology – have developed a new quantitative approach that can identify effective mixtures quickly and before the cell goes through production.

 thinfilm solar cell

Development of a thin-film solar cell. Image: science photo/Shutterstock

By using the solubility limit of a system as a parameter, the group looked to find the processing temperature providing the optimum performance and largest processing window for the system, said Harald Ade, co-corresponding author and Professor of Physics at NC State.

‘Forces between molecules within a solar cell’s layers govern how much they will mix – if they are very interactive they will mix but if they are repulsive they won’t,’ he said. ‘Efficient solar cells are a delicate balance. If the domains mix too much or too little, the charges can’t separate or be harvested effectively.’

tea gif

Originally posted by itadakimasu-letmeeat

‘We know that attraction and repulsion depend on temperature, much like sugar dissolving in coffee – the saturation, or maximum mixing of the sugar with the coffee, improves as the temperature increases. We figured out the saturation level of the ‘sugar in the coffee’ as a function of temperature,’ he said.

Organic solar cells are a type of photovoltaic –  which convert energy from the sun into electrons – that uses organic electronics to generate electricity. This type of cell can be produced cheaply, and is both lightweight and flexible, making it a popular option for use in solar panels.

 Photovoltaic systems

Photovoltaic systems are made up of organic solar cells that convert sunlight into energy. Image: Pxhere

However, difficulties in the production process, including an effective process to determine efficiency of potential material combinations, is stalling its development.

‘In the past, people mainly studied this parameter in systems at room temperature using crude approximations,’ said Long Ye, first author and postdoctoral researcher at NC State. ‘They couldn’t measure it with precision and at temperatures corresponding to processing conditions, which are much hotter.’

Faces of Chemistry: Organic solar cells at BASF. Video: Royal Society of Chemistry

‘The ability to measure and model this parameter will also offer valuable lessons about processing and not just material pairs.’

But the process still needs refinement, said Ade. ‘Our ultimate goal is to form a framework and experimental basis on which chemical structural variation might be evaluated by simulations on the computer before laborious synthesis is attempted,’ he said.