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    INSPIRATION AND CHAT

The History of Metal in Sheffield

Posted September 15th 2017

The city of Sheffield is well known for steel manufacturing and metallurgy. From the 18th century onwards it was quickly established as one of the main industrial cities in the UK, although it was recognised for the manufacture of knives as early as the 14th century with a notable mention from Chaucuer in The Reeve’s Tale.


Ay by his belt he baar a long panade,

And of a swerd ful trenchant was the blade.

A joly poppere baar he in his pouche;

Ther was no man, for peril, dorste hym touche.

A Sheffeld thwitel baar he in his hose.

Round was his face, and camus was his nose;


The location of the city, situated amongst a multitude of rivers and streams, made it ideal for water powered industries to flourish and in the 1600s, Sheffield became the hub of cutlery production in England, outside London. In the 1740s, Benjamin Huntsman, who lived just outside Sheffield in the town of Handsworth, invented a version of crucible steel process that would produce better quality steel than had previously been possible. His method involved a coke-fired furnace that could be heated to a staggering 1,600 degrees °C. Clay crucibles would first be heated, before adding an alloy of carbon and iron known as blister steel. After 3 hours in the furnace the pots were removed, and impurities skimmed off, before the molten steel was cast and cooled. Also notable at this time was the invention of Sheffield plate by Thomas Boulsover, a combination of layers of copper and silver that is very strong and was used to produce a multitude of household goods. Because there was a large amount of copper, covered with a thin coating of silver, items were able to be produced at a far lower cost than if they were made only of silver.

In 1912, Harry Brearly discovered stainless steel in his research laboratory based in Sheffield. The metal was marketed as Staybrite in England by Firth Vickers and was used in the new entrance to the Savoy Hotel in London in 1929. Although when he applied for a US patent Brearly found that someone in the US had already registered one, he was able to join forces with Elwood Haynes to create the American Stainless Steel Corporation.

As steel began to be mass-produced the population of the city grew exponentially from the 18th to the 20th century, going from 60,995 in 1801 to 577, 050 in 1951. Although the industry has since declined Sheffield is still recognised as a key contributor to the metal industry and continues to manufacture specialist steel today.

sheffield metal history

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Casting Metals

Posted September 7th 2017

‘Casting’ is a process used in metalworking where a metal in liquid form is poured into a mould and allowed to cool in the cavity to form a specific shape. It is a commonly used process for making complex shapes as the use of the mould allows for great detail and it is more economical than other processes might be. Once the metal has solidified it is removed from the mould and is known as a casting. Items commonly produced by casting include pieces of jewellery, sculptures, tools and some weapons.

The process of casting has been used for thousands of years, but it has been steadily refined and modern casting can now be broken down into two distinct sub-categories – expendable and non-expendable casting. In the expandable casting process, a temporary mould is used that cannot be reused, whereas in non-expendable casting the mould can be reused. This is then further differentiated by which material and which pouring method is used.

There are a variety of materials that can be used for casting, including non-metals such as sand and plaster. If using metal, the most common ones are iron, aluminium, steel, copper and zinc. When casting metals, a non-expendable method of casting is commonly used. For example, permanent mould casting uses a reusable mould, usually also made of metal, to cast metals such as iron, zinc, tin, aluminium and copper, amongst others. Usually, gravity is used to fill the mould, but vacuum or gas pressure can also be used. Another popular method is die casting which pushes molten metal into a mould using high pressure. Die casting usually uses non-ferrous metals such as zinc, copper and aluminium alloys, but it is also possible to use ferrous metals, although they are less common.

It is possible for defects to occur during the cooling period, also known as the solidification process, such as gas porosity and solidification shrinkage. Because of the nature of the casting process, it is difficult to do anything to prevent these from occurring so proper steps should be taken throughout the process to combat these. Shrinkage, for example, usually happens when the metal cooling in the mould is less dense in its liquid form, meaning as it cools to a solid the density decreases. In order to prevent this a suitable metal should be used.

casting metal

The origin of the steel skyscraper

Posted August 23rd 2017

Although they are undoubtedly still impressive, skyscrapers have become a common feature of modern cities that we have become accustomed to seeing on busy skylines such as New York and London. Constantly evolving, they push the limits of architectural design, with the Burj Khalifa pushing an imposing 828 metres in height. However, this is a far cry from the humble origins of the modern skyscraper which began in 1884 with a small structure of only 10 storeys in Chicago.
The Home Insurance Building of Chicago, designed by William Le Baron Jenney, was the first structure to utilize a steel skeleton on the interior to support its weight. This is one of main factors a building must have in order to be classed as a skyscraper in modern architecture so despite the relative lack of height, the Home Insurance Building is what kickstarted the evolution of skyscrapers.
Jenney was the man who came up with the idea of relying on the strength of metal to support his vision, rather than stone. At the time the building was constructed this was unheard of and the city of Chicago halted construction of the building at one point to investigate its stability, so new was the idea. Although Jenney initially thought an iron frame would be the best option, he switched this to steel half way through the project, which would go on to become an incredibly important decision.
As architects began to incorporate steel and other metals into the construction of their buildings, it became possible to start pushing the limitations of height as buildings became stronger and more stable. Although the first skyscraper may only have been 10 stories tall, todays skyscrapers are defined as having at least 40-50 floors and are usually higher than 100 metres, although many go far above this. Modern skyscrapers do not have load bearing walls as they used to, due to their height, and instead architects must consider how to counteract things like wind and seismic loads through their structure. Most modern skyscrapers use a tubular design, a concept made popular by designer Fazlur Rahman Khan in the 1960s, as this allows them greater flexibility in their design rather than having to confirm to a rectangular or box shape. There are many famous examples of both designs still in existence.
skyscraper

How does heating metal affect its properties?

Posted August 14th 2017

Applying heat to different metals can have a dramatic effect on them and can completely alter their structural, magnetic and electrical properties. There are several methods that can be used to change metals through heat, in order to enhance more favourable qualities, and the varying methods that are used will depend upon the metal and the desired result.

Thermal Expansion

Heating metal can increase its volume, length and surface area, as the heat displaces atoms from their usual position which alters the structure. This is known as thermal expansion and the amount of growth depends on the metal. Examples of this can be seen in everyday life when things such as pipework in bathrooms and the plumbing of houses expand and contract in hotter and cooler months. A common side effect of this is burst pipes.

Magnetism

Iron, cobalt and nickel are all naturally magnetic materials, or ferromagnetic materials. When heat is applied to them it can reduce their natural magnetic properties to a point so low that it is completely gone. This point, which is different for every metal, is known as the Curie temperature. For cobalt this is 1110 degrees Celsius whereas Nickel is much lower at only 330 degrees Celsius.

Resistance

Some metals are able to effectively reduce, or halt, the flow of an electric current. This is known as resistance and how resistant a metal is depends on how quickly electrons are able to pass through it. When metal is heated, electrons can gather energy more quickly which allows them to move faster and thus increases the level of resistance as they are more likely to scatter and collide. Similarly, a drop in temperature can result in a drop in resistance as the electrons move more slowly.

Different heat treatments include the processes of annealing, normalising, hardening and tempering. These are used to alter the properties of various metals and gain an end result better suited to the intended use of the metal. The aim may be to strengthen, soften, increase ductility or provide uniformity to name a few.

heating_metal

What is galvanizing?

Posted August 5th 2017

Galvanizing, or galvanization, is the term used for the process of applying a layer of zinc to steel or iron, in order to create a protective coating. It is commonly used as a method of protecting metals from corrosion as the layer of zinc prevents the metal from oxidizing.

There are several ways in which galvanizing can protect the base metal. Firstly, it creates a protective layer which protects the base metal from corrosion by offering sealed protection from the surrounding environment. The zinc will prevent elements such as water getting through, unless it is scratched or damaged badly enough to expose the metal underneath. The outer layer of zinc usually slows the corrosion of the base metal too, preserving its longevity through ‘galvanic corrosion’.

There are several methods of galvanizing.

Hot-dip galvanizing

The method of hot-dip galvanizing involves submerging the base metal in molten zinc, to produce a thick and robust ‘outer shell’. This method is quick to perform, which makes it economically attractive, but it is not suitable for use on everything and can be inconsistent in the results it produces.

Pre-galvanizing

Pre-galvanizing has similarities to hot-dip galvanizing and involves cleaning sheet metal before immersing it in hot, molten zinc. Large steel coils can be quickly galvanized using this method, with more reliable and uniform results than hot-dip galvanizing. However, once the coil is cut to produce smaller pieces of metal uncoated edges are left exposed.

Electro-galvanizing

Electro-galvanizing utilises an electric current to deposit zinc ions on the base metal, as opposed to melting the zinc like other methods. The zinc ions are deposited on the positively charged base metal, and in a similar way to pre-galvanizing this method is popularly used on large rolls of sheet metal. This method offers a consistently uniform coating, but it is generally thinner than the results obtained using the method of hot-dip galvanizing.

Although the process of galvanizing offers a lengthy period of protection, some damage is inevitable if exposed to the elements and over the years the coating will degrade. If proper measure are taken, such as regular paint coatings and maintenance then the life of the galvanized steel can be prolonged.

galv

The best mining museums in the UK

Posted July 21st 2017

Museum of Lead Mining

High in the hills of Scotland, in a village called Wanlockhead, is the Museum of Lead Mining, a Visit Scotland 4 Star Visitor Attraction and treasure trove of information about lead mining. The museum is set around a genuine 18th century lead mine which visitors can venture into on their tour, and shows how lead miners lived and worked at different periods as lead mining evolved. The museum offers daily guided tours of the mine, the miners cottages and the miners library, to give visitors a comprehensive and unique insight into the world of lead mining.

Keswick Mining Museum

Keswick Mining Museum explores the history of mining in Keswick, and how the industry has shaped the rural town throughout the centuries. Beginning with Copper and Lead, before progressing on to Borrowdale graphite, the mining industry here went through many stages of change before and eventually the mining of Slate, Coal and Iron dominated the town as the advent of the railway become more popular. As the first mining museum to be located in Cumbria it delivers a much-needed insight into the history of mining in the area and houses a lot of significant memorabilia.

Cleveland Ironstone Mining Museum

A celebration of ironstone mining, the Cleveland Ironstone Mining Museum is located on the site of Loftus Mine, the very first mine to be opened in Cleveland. Fittingly, it explores the rich history and subsequent legacy of iron mining in the UK, which at one time supplied iron to Europe, America, Africa, India and Australia, creating the railway infrastructure and bridges in these countries.

Peak District Lead Mining Museum

Offering guided tours and activities to suit children and adults of all ages, this museum explores the history of lead mining in the Derbyshire area. The museum itself is home to thousands of items that are displayed in different exhibits. Guided tours are also provided to Temple Mine where visitors can see how a mine worked during the 1920s and 1950s, as well as the equipment miners would have used.

Mining

Mining in Outer Space

Posted July 17th 2017

It may not be the first place that springs to mind when you think of a potential area for mining metals, but many metals can be found in outer space and as the supply on our planet dwindles, the discussion of how we can mine these metals becomes ever more serious.

Although it seems more suited to a science fiction novel than reality, mining in space is something now being approached as a potentially viable option. For example, Deep Space Industries is a company developed to meet the potential need for asteroid mining and one which, according to their website, provides ‘the technical resources, capabilities and system integration required to prospect for, harvest, process, manufacture and market in-space resources.’ They acknowledge their missing as ‘a daring one’, and yet it cannot be denied that the ability to mine certain materials from space would be a huge benefit for us.

Meteorites that have fallen to earth in the past of yielded huge amounts of precious metals such as platinum, gold, palladium, iridium and rhodium. As these are only small chunks of larger asteroids, the amounts of metal that a full asteroid could contain are potentially huge. Bernstein, a Wall Street research firm, asserts that one particular asteroid known as ’16 Psyche’, could contain more than 17 million billion tons of nickel-iron. An amount like this would be enough to provide for our current needs for millions of years.

Despite this, travel into space in order to mine these materials is still a distant dream and in order to get there huge developments are still needed in the space travel industry. Who knows what the future holds?

mining_outer_space

Fears for patients with ‘metal-on-metal’ hip implants

Posted July 5th 2017

An alert issued by the Medicines and Healthcare products Regulatory Agency (MHRA) means that thousands of people could be at risk of damage from ‘metal-on-metal’ hip implants which have raised concerns over their levels of toxicity.

The implants are thought to have been used on approximately 56,000 people in the UK and will be recalled for testing amidst fears that they could cause bone or muscle damage if any metal particles have detached and settled into the surrounding tissue. If this is the case, then further surgery could be required. Although patients with smaller size implants have not been considered high risk in the past this view has now changed to consider all patients with this type of implant at potential risk.

Dr Neil McGuire, clinical director of medical devices for the MHRA, said, ‘We’ve now included a group of people who were at low risk, but were not at no risk. It’s more about catching people who could be developing these complications early.’

Whilst the MHRA has stated that it does not anticipate an increase in the number of revision surgeries that will need to be performed, thousands of extra patients will now need to undergo testing to rule them out. McGuire also stated that ‘although the majority of patients with these metal-on-metal devices have well-functioning hips, it is known some may develop soft tissue reactions related to their implant. The clinical advice we have received indicates patients will likely have the best outcomes if these problems are detected early, monitored and treated if necessary’.

MHRC

The environmental consequences of our smartphone addiction

Posted June 26th 2017

Most of us now use smartphones on a daily basis, but we give little thought as to the materials contained within them. All smartphones contain a mix of precious metals such as platinum, palladium, gold, silver and copper.

A typical iPhone, one of the most predominant smartphones on the market, contains a mix of 0.034g of gold, 0.34g of silver, 0.015g of palladium and a very small amount of platinum (under a thousandth of a gram). In addition to this it also contains 25g of aluminium and 15g of copper.

Around 40% of a standard smartphone is composed of metals and the unfortunately less than 10% of these handsets are typically recycled which means the materials contained within them are not able to be recovered and used again. When you consider the sheer number of people who own a smartphone – over two billion – and the fact that most people will typically upgrade their phone every 1-2 years, the amount of material going to waste is staggering. With the smartphone obsession looking more likely to grow rather than fizzle out any time soon, the implications of this are important. These are finite resources and cannot just be tapped endlessly – there is a limit to what is available.

One solution would be to decrease the frequency with which we change smartphones, although this is highly unlikely to work in practice. It is, however, important to make people aware of the implications of their behaviour and encourage them to consider this. Awareness could also help to recover some of the materials sitting in old smartphones if people are encouraged to return them. Just one million old handsets could be turned into almost 16 tonnes of copper, 350kg of silver, 15 kg of palladium and 34kg of gold.

Although there is no clear solution this is certainly a problem that needs to be talked about. Awareness can help to alter people’s behaviour and may help us to preserve and recover some of these much needed resources.

metals in smartphone

 

The different types of stainless steel

Posted June 21st 2017

Stainless steel is an immensely popular steel alloy that is highly prized for its resistance to corrosion and used in a variety of ways, including cutlery, medicine and jewelry. There are different types of stainless steel and the type will depend on what has been added to it. The fact that different varieties can be formed gives this an alloy an immense versatility which explains its popularity and suitability for a wide number of applications.

Austenitic

Austenitic stainless steel can also be referred to as the 300 series and is formed by adding 18% chromium and 8% nickel. Over 70% of stainless steel production is for austenitic steel and it is popularly used in kitchens and food processing equipment due to its excellent hygiene properties.

Ferritic

Ferritic stainless steels are usually cheaper and often have better engineering qualities than austenitic. They can contain up to 27% chromium and their high resistance to corrosion means they can be used in severe environments, such as being submerged in seawater for prolonged periods of time, although austenitic is still more durable.

Martensitic

Less durable than ferritic and austenitic steels, martensitic was one of the first to be commercially produced and is still very strong. It contains up to 18% chromium with a very low amount of nickel and molybdenum. High temperatures can make it harder and it has commonly been used in cutlery, as well as pins and surgical instruments.

Duplex

Duplex stainless steels are a mix of austenitic and ferritic, or at least the components that make them. The mix is usually half and half, although it can be slightly more weighted to in a 60/40 split, and has a high chromium content of up to 32% as well as low nickel and usually around 5% molybdeneum. The best qualities of each type show up in this version, which is highly resistant to corrosion, more so than any other variety, as well as strong and sometimes magnetic. Standard duplex is the variety most widely used but super duplex also exists which is considered the very best quality of stainless steel.

steel types