Category Science

WHAT ARE CERAMICS?

Ceramics are materials made from stony or earthy material taken from the ground. Some ceramics, such as pottery and bricks, are moulded into shape and then baked (fired) to make them set. Glass is a type of ceramic that is heated first and then moulded into shape. Some ceramic materials are able to with-stand very high temperatures and are used for specialist application in industry and engineering.

Ceramic materials are special because of their properties. They typically possess high melting points, low electrical and thermal conductivity values, and high compressive strengths. Also they are generally hard and brittle with very good chemical and thermal stability. Ceramic materials can be categorized as traditional ceramics and advanced ceramics. Ceramic materials like clay are categorized as traditional ceramics and normally they are made of clay, silica, and feldspar. As its name suggests, traditional ceramics are not supposed to meet rigid specific properties after their production, so cheap technologies are utilized for most of the production processes.

Ball clay, China clay, Feldspar, Silica, Dolomite, Talc, Calcite and Nepheline are the common materials used for most of the ceramic products. Each raw material contributes a certain property such as dry strength, plasticity, shrinkage, etc. to the ceramic body. Therefore, by careful selection of materials, desired properties are acquired for the final output. Powder preparation is a major consideration in the ceramic industry. Surface area, particle size and distribution, particle shape, density, etc. each have their own effect on production. Powder has to be prepared to meet required particle size, particle shape, and other requirements for a particular industry. Milling is done to get the desired particle size. Unlike in the, advanced ceramics industry the purity of ceramic powder is not an issue in traditional ceramics.

The traditional ceramics industry originated long ago. Even thousands of years ago it was a well-established practice in many parts of the world. Today there are many divisions of this industry. Pottery, tableware, sanitary ware, tiles, structural clay products, refractories, blocks, and electrical porcelain are some of the products of traditional ceramics.

Advanced ceramics are special type of ceramics used mainly for electrical, electronic, optical, and magnetic applications. This sector is different from traditional ceramics due to the fact that ceramic powder preparation is quite important. Advanced production techniques are employed to assure that the produced ceramic powders possess sufficient purity. Generally chemical reactions are used to produce the ceramic powder such as Sol-gel processing and liquid-gas reactions like NH3 gas and SiCl4 liquid to produce Si3N4. Many of these methods are very costly. Therefore, powder preparation is always a cost factor in the advanced ceramics industry.

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HOW ARE TREES USED TO MAKE PAPER?

Trees are made up of thousands of tiny fibres. The paper-making process extracts these fibres and arranges them in a crisscross pattern. Wood is broken up into small pieces and then chemically treated to break it down into fibres. Most paper is produced from softwood trees such as spruce and pine.

Making pulp

1 Several processes are commonly used to convert logs to wood pulp. In the mechanical process, logs are first tumbled in drums to remove the bark. The logs are then sent to grinders, which break the wood down into pulp by pressing it between huge revolving slabs. The pulp is filtered to remove foreign objects. In the chemical process, wood chips from de-barked logs are cooked in a chemical solution. This is done in huge vats called digesters. The chips are fed into the digester, and then boiled at high pressure in a solution of

sodium hydroxide and sodium sulfide. The chips dissolve into pulp in the solution. Next the pulp is sent through filters. Bleach may be added at this stage, or colorings. The pulp is sent to the paper plant.

Beating

2 The pulp is next put through a pounding and squeezing process called, appropriately enough, beating. Inside a large tub, the pulp is subjected to the effect of machine beaters. At this point, various filler materials can be added such as chalks, clays, or chemicals such as titanium oxide. These additives will influence the opacity and other qualities of the final product. Sizings are also added at this point. Sizing affects the way the paper will react with various inks. Without any sizing at all, a paper will be too absorbent for most uses except as a desk blotter. A sizing such as starch makes the paper resistant to water-based ink (inks actually sit on top of a sheet of paper, rather than sinking in). A variety of sizings, generally rosins and gums, is available depending on the eventual use of the paper. Paper that will receive a printed design, such as gift wrapping, requires a particular formula of sizing that will make the paper accept the printing properly.

Pulp to paper

3 In order to finally turn the pulp into paper, the pulp is fed or pumped into giant, automated machines. One common type is called the Fourdrinier machine, which was invented in England in 1807. Pulp is fed into the Fourdrinier machine on a moving belt of fine mesh screening. The pulp is squeezed through a series of rollers, while suction devices below the belt drain off water. If the paper is to receive a water-mark, a device called a dandy moves across the sheet of pulp and presses a design into it.

The paper then moves onto the press section of the machine, where it is pressed between rollers of wool felt. The paper then passes over a series of steam-heated cylinders to remove the remaining water. A large machine may have from 40 to 70 drying cylinders.

Finishing

4 Finally, the dried paper is wound onto large reels, where it will be further processed depending on its ultimate use. Paper is smoothed and compacted further by passing through metal rollers called calendars. A particular finish, whether soft and dull or hard and shiny, can be imparted by the calendars.

The paper may be further finished by passing through a vat of sizing material. It may also receive a coating, which is either brushed on or rolled on. Coating adds chemicals or pigments to the paper’s surface, supplementing the sizings and fillers from earlier in the process. Fine clay is often used as a coating. The paper may next be supercalendered, that is, run through extremely smooth calendar rollers, for a final time. Then the paper is cut to the desired size.

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HOW DOES INDUSTRY USE RAW MATERIALS?

Most of the world’s industry involves working with raw materials extracted from the earth. As well as fossil fuels, minerals such as salt, clay and sulphur, and metals including copper and iron ore are all extracted for industrial purposes. The extraction of such materials is described as primary industry; activities that convert them into other products are known as secondary industries.

Raw materials are used in a multitude of products. They can take many different forms. The kind of raw materials inventory a company needs will depend on the type of manufacturing they do. For manufacturing companies, raw materials inventory requires detailed budgeting and a special framework for accounting on the balance sheet and income statement.

In some cases, raw materials may be divided into two categories: direct and indirect. Whether a raw material is direct or indirect will influence where it is reported on the balance sheet and how it is expensed on the income statement.

Direct raw materials are materials that companies directly use in the manufacturing of a finished product, such as wood for a chair. Indirect raw materials are not part of the final product but are instead used comprehensively in the production process.

Indirect raw materials will be recorded as long-term assets. Within long-term assets, they can fall under several different categories including selling, general, and administrative or property, plant, and equipment. Long-term assets usually follow some depreciation schedule which allows the assets to be expensed over time and matched with revenue they help to produce. For indirect raw materials, depreciation timing will usually be shorter than other long-term assets like a building expensed over several years.

Direct raw materials are placed in current assets as discussed above. Direct raw materials are expensed on the income statement within cost of goods sold. Manufacturing companies must also take added steps over non-manufacturing companies to create more detailed expense reporting on costs of goods sold. Direct raw materials are typically considered variable costs since the amount used depends on the quantities being produced.

A manufacturer calculates the amount of direct raw materials it needs for specific periods to ensure there are no shortages. By closely tracking the amount of direct raw materials bought and used, an entity can reduce unnecessary inventory stock, potentially lower ordering costs, and reduce the risk of material obsolescence.

Raw materials may degrade in storage or become unusable in a product for various reasons. In this case, the company declares them obsolete. If this occurs, the company expenses the inventory as a debit to write-offs and credits the obsolete inventory to decrease assets.

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WHERE DOES NUCLEAR ENERGY COME FROM?

Nuclear power plants use radioactive materials such as uranium or plutonium- to power their steam turbines. The atoms of these materials decay, producing heat energy inside a nuclear reactor. Nuclear energy is a “clean” fuel, in that it does not produce the polluting gases that burning fossil fuels do. However, the disposal of used nuclear fuel is hazardous, expensive and poses serious environmental risks.

Nuclear energy is the energy in the nucleus, or core, of an atom. Atoms are tiny units that make up all matter in the universe, and energy is what holds the nucleus together. There is a huge amount of energy in an atom’s dense nucleus. In fact, the power that holds the nucleus together is officially called the “strong force.”

Nuclear energy can be used to create electricity, but it must first be released from the atom. In the process of nuclear fission, atoms are split to release that energy.

A nuclear reactor, or power plant, is a series of machines that can control nuclear fission to produce electricity. The fuel that nuclear reactors use to produce nuclear fission is pellets of the element uranium. In a nuclear reactor, atoms of uranium are forced to break apart. As they split, the atoms release tiny particles called fission products. Fission products cause other uranium atoms to split, starting a chain reaction.

The energy released from this chain reaction creates heat.

The heat created by nuclear fission warms the reactor’s cooling agent. A cooling agent is usually water, but some nuclear reactors use liquid metal or molten salt. The cooling agent, heated by nuclear fission, produces steam. The steam turns turbines, or wheels turned by a flowing current. The turbines drive generators, or engines that create electricity.

Rods of material called nuclear poison can adjust how much electricity is produced. Nuclear poisons are materials, such as a type of the element xenon, that absorb some of the fission products created by nuclear fission. The more rods of nuclear poison that are present during the chain reaction, the slower and more controlled the reaction will be. Removing the rods will allow a stronger chain reaction and create more electricity.

As of 2011, about 15 percent of the world’s electricity is generated by nuclear power plants. The United States has more than 100 reactors, although it creates most of its electricity from fossil fuels and hydroelectric energy. Nations such as Lithuania, France, and Slovakia create almost all of their electricity from nuclear power plants. Nuclear power plants produce renewable, clean energy. They do not pollute the air or release greenhouse gases. They can be built in urban or rural areas, and do not radically alter the environment around them.

The steam powering the turbines and generators is ultimately recycled. It is cooled down in a separate structure called a cooling tower. The steam turns back into water and can be used again to produce more electricity. Excess steam is simply recycled into the atmosphere, where it does little harm as clean water vapor.

However, the byproduct of nuclear energy is radioactive material. Radioactive material is a collection of unstable atomic nuclei. These nuclei lose their energy and can affect many materials around them, including organisms and the environment. Radioactive material can be extremely toxic, causing burns and increasing the risk for cancers, blood diseases, and bone decay.

Radioactive waste is what is left over from the operation of a nuclear reactor. Radioactive waste is mostly protective clothing worn by workers, tools, and any other material that have been in contact with radioactive dust. Radioactive waste is long-lasting. Materials like clothes and tools can stay radioactive for thousands of years. The government regulates how these materials are disposed of so they don’t contaminate anything else.

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CAN WASTE PRODUCTS BE USED FOR ENERGY?

Some power stations are able to burn waste products that would otherwise be buried in the ground. Even waste that is already buried can be put to use by harnessing the methane gas that decaying matter gives off. Once purified, the gas can he piped to homes, or used in power stations. However, while it solves the problem of what to do with rubbish, burning waste releases gases into the atmosphere, creating a pollution problem of its own.

Since the industrial revolution, waste has been a major environmental issue worldwide. Wastes are materials we don’t need and thrown as trash. Europe creates over 1.8 billion tonnes of wastes each year. In Australia, 50 million tonnes of waste is generated each year. According to the UK Statistics on Waste, UK generated 202.8 million tonnes of waste in 2014. The total volume of waste is the measure of the overall impact of human activity on the environment. But, we can turn these tonnes of trash into treasure by turning them into energy.

Waste to energy is the process of producing thermal energy from the organic waste. Most wastes to energy processes produce electricity or heat energy directly through combustion.

Waste can be solid or liquid. Both types of waste can be hazardous. Liquid waste can come in non-solid form. Examples of liquid waste include wash water, liquid used to clean in industries. On the other hand, solid waste is any garbage and rubbish we make at our home or any places. Examples of solid waste include car tyres, newspapers, broken glass, broken furniture and even food waste. Hazardous or harmful waste is a threat to human health and environment. This type of waste can easily catch fire, explode and be poisonous to human health. Examples of these types of waste are chemicals, mercury-containing equipment, fluorescent bulbs, battery etc.

The wastes we are producing every day can be turned into something good. Such as electricity, heat or fuel. The solid wastes can be converted into gas to produce energy. We can generate electricity by burning solid waste found in the landfills. A community must have a waste to energy facility that incinerates garbage and transforms chemical energy into thermal energy.

The following methods are used to turn waste into energy. The most common technology for waste to energy conversion is incineration. In this process, the organics collected from the waste has burnt at a high temperature. This type of treatment is called thermal treatment. The heat generated from this thermal treatment then used to create energy.

This technology uses thermal decomposition in the presence of water. In this process, organic compounds from waste are heated at a high temperature to create thermal energy. In this process, we can generate fossil fuels from the waste. The process of thermal decomposition is also called Hydrous Pyrolysis.

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WHAT IS SOLAR POWER?

Solar-power systems convert light energy from the Sun into electricity using photo-voltaic cells. These cells are similar to those used to power pocket calculators, but used on a larger scale they can provide electricity for homes and businesses in areas away from a regular power supply. Most solar-power systems work by charging batteries that store the electricity for later use, act as a back-up system for a conventional power supply. Solar power is also used to heat water.

Solar energy is the most abundant energy resource on Earth. It can be captured and used in several ways, and as a renewable energy source, is an important part of our clean energy future. The sun does more than for our planet than just provide light during the daytime – each particle of sunlight (called a photon) that reaches Earth contains energy that fuels our planet. Solar energy is the ultimate source responsible for all of our weather systems and energy sources on Earth, and enough solar radiation hits the surface of the planet each hour to theoretically fill our global energy needs for nearly an entire year.

Where does all of this energy come from? Our sun, like any star in the galaxy, is like a massive nuclear reactor. Deep in the Sun’s core, nuclear fusion reactions produce massive amounts of energy that radiates outward from the Sun’s surface and into space in the form of light and heat.

Solar power can be harnessed and converted to usable energy using photovoltaics or solar thermal collectors. Although solar energy only accounts for a small amount of overall global energy use, the falling cost of installing solar panels means that more and more people in more places can take advantage of solar energy. Solar is a clean, renewable energy resourcec, and figures to play an important part in the global energy future.

A common way for property owners to take advantage of solar energy is with a photovoltaic (PV) solar system. With a solar PV system, solar panels convert sunlight right into electricity that can be used immediately, stored in a solar battery, or sent to the electric grid for credits on your electric bill.

Solar panels covert solar energy into usable electricity through a process known as the photovoltaic effect. Incoming sunlight strikes a semiconductor material (typically silicon) and knocks electrons loose, setting them in motion and generating an electric current that can be captured with wiring. This current is known as direct current (DC) electricity and must be converted to alternating current (AC) electricity using a solar inverter. This conversion is necessary because the U.S. electric grid operates using AC electricity, as do most household electric appliances.

Solar energy can be captured at many scales using photovoltaics, and installing solar panels is a smart way to save money on your electric bill while reducing your dependence on nonrenewable fossil fuels. Large companies and electric utilities can also benefit from photovoltaic solar energy generation by installing large solar arrays that can power company operations or supply energy to the electric grid.

A second way to use solar energy is to capture the heat from solar radiation directly and use that heat in a variety of ways. Solar thermal energy has a broader range of uses than a photovoltaic system, but using solar thermal energy for electricity generation at small scales is not as practical as using photovoltaics.

There are three general types of solar thermal energy used: low-temperature, used for heating and cooling; mid-temperature, used for heating water; and high-temperature, used for electrical power generation.

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