Ceramics are any inorganic non-metallic material. Examples of ceramics can be from table salt to clay (complex silicate) some scientists say that ceramics must also be crystalline. This means that the molecules of the material are arranged in a regular pattern. The materials that are inorganic non-metallic but do not have a crystalline structure are called amorphous. An everyday example of an amorphous material is glass. This ranges from glass in bottles to the high purity glass in optical fibres
Some useful properties of ceramics are: high melting points, low density, high strength, stiffness, hardness, wear resistance, and corrosion resistance. Many ceramics are good electrical and thermal insulators. Certain ceramics have special properties. Some are magnetic or super conductors. Ceramics do have one major draw back; they are very brittle
Traditional ceramics are materials such as clay, talc, and porcelain that make products like pottery, bricks and containers for food.
Engineered ceramics are materials including silicon and aluminium nitride that make products such as sensors dental restoration and artificial bone implants.
Metals can be separated into two groups, these are pure metals and metal alloys, pure metals are single elements from the periodic table. Iron and copper are examples of pure metals. Metal alloys are a combination of more than one pure metal. For example stainless steal is a combination of iron nickel and chromium
All metals are crystalline structures and they all have tight atomic bonds. This means that each atom in the metal forms as many bonds with other atoms as it possibly can.
Properties of metals.
Metals all have various and different properties. But they all have some similar properties. In general they all have a good electrical and thermal conductivity. This is the property that allows metal to carry electricity and heat. Some metals are extremely good conductors but some metals are not as efficient
Most metals are very strong and have high stiffness. This means it is hard to bend. Also some metals are magnetic but not all of them are. Most metals and alloys have high density due to the tight structure of the atoms. This means they are useful when a high mass but small volume is needed. (17-19) For example a weight lifter wants a heavy weight but he does not want it so big that it over balances him or is to awkward to lift.
Metals also have high fracture toughness. This means that they can survive impacts without breaking and that they are durable. This is used in cars to prevent injuries to the passengers. The metal will bend in a crash but it will be hard for it to shatter and break.
“Hardness is the ability of metal to resist abrasion cutting or permanent distortion” (Jennifer 2003)
The hardness and strength of metals are very closely related. Heat-treating the metal can increase the hardness of metal.
Metal can be brittle instead of tough. This means that a metal will not bend or change shape but it is likely to crack or break. Metal can be hammered or pressed into different shapes to make things. Metals that can be changed are called malleable.
Copper is a malleable metal as it is used to make coins. Ductile metals can be permanently bent and twisted into various shapes without breaking; this is a good property for metal to have when making wire,
Metals are elastic; this means that it will go back into its original shape after it has been distorted. This is useful because for example if a metal has been carrying a heavy load it will bend but if it does not bend back it will be useless.
Polymer means many units. So a polymer has a repeating structure that results in a large chain like molecules. Polymers are lightweight cheap to make and generally resistant to corrosion. Polymers have various important properties. These include their molecule weight, and there softening and melting point. The mechanical properties include low strength and high toughness.
Polymers can be crystalline or amorphous but they are usually a combination of the two making them semi- crystalline. The chains in polymers can slide past each other, which make them thermoplastic, or they can be thermoset/ elastomers that do not allow movement as they are connected.
Composites are made from more than one material. Examples of this are polymer/ceramic and metal/ceramic composites. Composites are used due to them taking the best properties from each material. A polymer/ceramic material will have a higher melting point than a polymer but be less brittle than a ceramic. Composites can also be natural materials such as wood as it contains cellulose fibres,
Composites are divided into two categories, fibre reinforced composites and particle reinforced composites. Fibre reinforced composites can be made of metals ceramics glass or polymers. It is difficult to process fibre reinforced composites so they are generally expensive to buy. The carbon fibre in race bikes is an example of the fibre-reinforced composite. The bikes that use it are very expensive and only top-level athletes use them.
Partial reinforced composites include ceramics glasses and metal particles like aluminium. The particles decrease the ductility of the material. The particles are also used to make cheaper composites.
Swimming technology advances.
Swimming has been around for a very long time. No one is completely sure when swimming first came around. Some people say the Romans invented swimming so that their soldiers could advance across deep lakes and rivers without needing bridges or wasting time walking around. Swimming was also used in India as a form of mediation but this was more floating than swimming. The English are considered the first modern society to develop swimming, as a sport and Swimming became a recognised sport by 1837. But the sport has continued to develop with more rules and the final definition of the strokes. As swimmers have become increasingly faster and split seconds can be the difference between first and second the athletes have turned to technology to increase their performance.
Full-length suits are now the most popular costume in high level swimming competitions. These suits have been designed to reduce drag and friction whilst moving through the water. The suits are made to increase streamlining, as this will enable a swimmer to move faster with less effort. The design of the material used in the speed suits are based on the V-shaped ridges on a sharks skin. The v- shaped ridges are called denticles and they decrease drag and turbulence around a shark’s body. This means that the water can pass over the body more effectively. The material is very elastic so it fits tight and has a wide range of movement
Swimming goggles have also been improved since they were first used. The goggles are made of polycarbonate that is a shatter resistant plastic. The goggles are scratch resistant and also have a high optical clarity. Before the new type of polycarbonate goggles, goggles were made of glass. This was not very good as the glass was not very durable and there was a high risk to the wearer if the goggles were to smash in the person’s eye. The manufactures of goggles use a PVC plastic strip and neoprene seals to keep goggles watertight.
In the beginning, there was nylon, a relatively cheap material whose only purpose was to cover the bodies of the men or women swimming. In use for the greater half of the 20th century, the nylon suit proved to be a good cover for the body but nothing more. They became too heavy when wet and increased the surface drag of a swimmer when they swam at high velocities. As there were now more advances in the field of swimming technique, more advances had to be made in the field of swimming equipment.
In the 1973 World Aquatic Championship Games in Belgrade, lycra was introduced to competitive swimming. The material was lighter, thinner and fit closer to the body. Athletes felt smoother as there was less turbulence around them in the water and they were travelling higher on the water than before as the lycra did not weigh them down as much when wet as the nylon. This new discovery sparked interest in swimsuit materials and more research and development began to take place. Lycra was temporarily replaced in the eighties when ‘paper suits’ became a new fad in the world of competitive swimming; lycra is still the most frequently used swimsuits. Similar to swimming nude, ‘paper’ suits were incredibly thin and almost transparent that’s why they’re called paper. They were worn incredibly tight on the body and improved only the buoyancy of the swimmer. It produced about the same effects of surface drag on the swimmer as lycra did as they are both 82% polyester and 18% spandex. Paper is, however, woven while lycra is knitted. The paper suit craze quickly faded among competitive swimmers when the Aquablade and Sharkskin suits were displayed at the 1996 Atlanta Olympic Games.
The Aquablade swimsuits contain slick, water repellent resin to make contrasting rough and smooth stripes on the suit. The principle behind the suit is that the two stripes generate a slow and a fast current causing vortexes to be formed when the two currents interact. As a result, the water stays closer to the body longer and hence there is less turbulence and dispersion of water around the swimmer allowing him to ‘blade through the water’.
The newest models of swimsuits is the Speedo body suit made with the patented Fastskin Fabric by Speedo for their line of Sharkskin swimsuits and the other is the Addidas Equipment bodysuit made out of a material resembling that of Speedo’s. Made of super-stretch fabric, the Speedo suits fit the body snugly and compress the muscles of the swimmer which proves – according to Speedo – to be more efficient since muscles work in groups. Speedo has also created an anatomic/dynamic pattern where seams on the suits act like muscles and tendons as they stretch with overall hand and body movement.
The new suit technology is very controversial and some people still believe that it does not help the swimmer and others believe it is unfair for some people to use the suits but not others. Either way the technology has advanced and due to new materials the equipment in sport will always continue to be modernised and made more effective.
Brent S. Rushall. The Swmming Science Journal
Bergen, P. [01/28/2001] Coach Paul Bergen’s Test of Body Suits
Sanders, R, Rushall, B.S.,Toussaint, H, Stager, J, & Takagi, H [04/24/2001] Bodysuit Yourself: But think about it first.
Jennifer Stafford Brown, Simon Rea, John Chance (2003), BTEC National In Sport and Exercise Science, Abdington, Oxon
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