PBL 1 Name:Tan Ye Wei Class:4s4 Title:Manufactured Substances In Industry Teacher: Puan Chan Chapter 8: Manufactured Substances In Industry i) a) Glass Brittle (not tough) High in Hardness Obtained by heating silica with other chemical Transpare nt & chemicall y inert Heat insulator Waterpro of Electrical insulator
i) b) Soda-Lime glass Fused silica glass Brosilicate glass Lead crystal glass Type of Glass Properties Fused silica glass ⚫ Made with silica alone ⚫ Melting point of 1800C ⚫ Does not expand nor contract to change in temperature ⚫ Telescope lenses Soda-Lime glass ⚫ Made with silica, soda and limestone ⚫ Melting point of 1000C ⚫ Easily moulded ⚫ Cannot withstand high temperature ⚫ Glass containers and jugs Brosilicate glass ⚫ Made with silica, soda, limestone, boron oxide and aluminium oxide ⚫ Heat resistant ⚫ Do not crack easily when subjected to thermal stress(low expansion coefficient) ⚫ Laboratory glassware like beakers Lead crystal glass ⚫ Made with silica, soda and Lead(II) oxide ⚫ Soft and dense ⚫ Heavy and has high refractive index ⚫ Prisms
ii) a) ii)b) Types and properties of ceramic Traditional Ceramic ⚫ Made of clay that is mixed with water ⚫ Soft and mouldable ⚫ High melting point Advanced Ceramic ⚫ Made from inorganic compounds like oxides, carbides and nitrides ⚫ Possess higher heat resistance and chemically inert and superconductivity properties ⚫ Silicon carbide that is used to make brakes is high in hardness and strength and can withstand thermal shocks. Example of ceramic uses Medicine ⚫ Zirconia ceramic used in dental implants ⚫ Used in MRI machines due to its superconductivity properties Transportation ⚫ Jet engines are made of ceramics due to its heat resistance Energy production ⚫ Electrical insulators in high voltage areas such as power stations Ceramic Chemi cally inert Shatter easily (low toughenss) High thermal resistanc e Made of inorganic and non metallic substance Heat insulat or Produce through shaping and hardening High in hardness and strength Electrical insulator
iii) a) Composite material also known as composition material is a type of material that is composed of two or more non-homogeneous substances which is substances which possess notably dissimilar physical and chemical properties together. It is made by combining a matrix substance together with a strengthening substance. The matrix substance act as a substance that binds strengthening substances together. Composite materials reap beneficial properties from its original material, this is why it is superior physically and chemically to its original counterpart and its use is ideal in the engineering industry.Many items we use every day is made from the innovation of composite materials. iii)b) 1. Reinforced concrete Concrete which is a type of ceramic can resist high compression force due to its atoms in indefinite arrangements but has low resistance towards stretching force. This problem can be solved by immersing steel bars which has high hardness, toughness and strength into concrete which acts as a matrix substance for the steel bars.Corrosion to steel bars is prevented by using the galvanizing technique, which envelops the steel in a more reactive material. Reinforced concrete is essential in building structures like bridges and skyscrapers
2. Fibreglass Fibreglass is a composite material obtained by merging plastic, a matrix substance with glass fibres. The glass fibres are arranged randomly into a mouldably flat sheet. Often said to be similar to carbon fibre, it is stronger than many metals when compared pound for pound. It is also non-magnetic, transparent to electromagnetic radiation, fire resistant, electrically insulated and compatible with organic matrices. However glass fibres in fibre glass is small in size and may cause health issues when inhaled into the lungs or handled without proper equipments. Fibreglass is used for building insulation but other substances like aerogel has started to replace it. Besides that it is also used to make boats, aircrafts, pipes and printed circuit boards. 3. Optical Fibre Optical fibre is a composite material consisting three layers, the innermost layer is the core that is made of silica glass fibres, which is encased in a layer of cladding, the matrix substance made with plastic or glass, which is then encased in a layer of plastic which is another matrix substance. Optical fibres are thin strands of glass fibre that are transparent, flexible, lightweight,resistant to corrosion and immune to electromagnetic interferences. This makes it a great way to transmit information in a short period of time through a long distance in the form of light impulses. This is possible because of the fact that light travels at a very high speed and the natural phenomenon called total internal reflection, which is when the cladding has a lower refractive index compared to the core, allowing light to repeatedly be reflacted indefinately to the other end of the cable. Sometimes light is still loss but can be fixed by using a repeater which repeats the same signal. Hundreds of tiny optical fibre strands are in one cable that is laid under the sea and these cables are incredibly essential to allow intercontinental communication as well as other every day uses therefore we should appreciate its existence. Fibre Optics are way superior than copper wires for long distances because copper is not a perfect conductor that will prevent energy loss in the form of heat, copper wires can also be interefered by electromagnetic waves and is slower the speed of light. Optical fibre is used to make fibre optic cables, light decorations as well as video cameras.
Map of fibre optic cables in around the world 4. Superconductors Superconductor is a composite material that possess superconductivity properties. Superconductivity is a rather recent and modern concept that contributes to many mindblowing science and technological advancements, such as particle accelerators. Superconductivity is a phenomenon whereby electrons that flow through a substance does not create energy loss in heat and light, in other words, a perfect conductor. For example, copper is a common metal used in almost every electrical appliances in our homes, whilst it is a good conductor, it still has little electrical resistance. Electrical resistance resist the flow of electrons, causing electrons to bump into the copper atoms when passing through, creating energy loss in the form of heat, this is precisely
why our computers and cellphone heat up when operated for long period of time, and also why the metal elements in toaster have a high electrical resistance purposed to generate heat. Superconductor allows electrons to flow through with absolutely zero resistance, greatly increasing its efficientcy. However the phenomenon of superconductivity only works when the critical temperature is met, that is usually very low. This is why we don’t have superconductive every day electrical appliances like our phones. That being said scientists are working hard to increase the critical temperature to room temperature. Another thing is that superconductors allow us to create strong magnetic field allowing magnetic metals to freely move whilst being suspended in the air as shown in the picture above. One type of superconductor is the YBCO (Yttrium Barium Copper Oxide) superconductor, it is used in the medical field to make MRI (Magnetic Resonance Imaging) machines, and also in chemistry field to make NMR(Nuclear Magnetic Resonance) and particle accelerators. Particle accelerators is a machine that launch subatomic particles at elements, usually at heavy metals to create isotopes and sometimes create new elements.One notable use of it is in the creation of element 118, oganneson. 5. Photochromic glass Photochromic glass is a composite material made with glass, a matrix substance, silver chloride and copper chloride. Photochromic glass is a type of glass that when exposed to UV light, darkens and becomes slightly translucent. This is due to the formation of silver atoms that prevent the passage of light, meanwhile copper reverses the process and turns the glass back transparent after a period of time. Photochromic glass is used to make Car windows that darkens under UV rays, glasses that darkens when exposed to UV ray, acting like sunglasses, camera lenses as well as building windows. However it is usually on the pricey side due to its use of silver.