0-49982764796325655371.pptx
- 2. INTRODUCTION Metals possess many unique fundamental properties that make them an ideal material for use in a diverse range of applications. Structures ranging from bridges, silos and tractors to gym lockers and lawn mowers all contain some form of metal. Metals are chemical elements that are known generally for their metallic luster, strength, hardness, and ability to conduct heat and electricity. Metals are nerally not used in their pure state but as mixtures of etals or metal and non-metal constituents commonly referred to as alloys.
- 3. Metallic bonding is the main type of chemical bond that forms between metal atoms. Metallic bond is a force that holds atoms together in a metallic substance. Such a solid consists of closely packed atoms. In most cases, the outermost electron shell of each of the metal atoms overlaps with a large number of neighbouring atoms. As a consequence, the valence electrons continually move from one atom to another and are not associated with any specific pair of atoms. In short, the valence electrons in a metal are delocalized because they spread out and do not stay with any one nucleus. The atoms that the electrons leave behind become positive ions, and the interaction between such ions and valence electrons gives rise to the binding force that holds the metallic bond together.
- 4. PropertiesofMetals METALSARELUSTROUS in nature. They have shiny appearance METALSAREMALLEABLE § Metals are malleable because their atoms can move past each without breaking the metallic bond, therefore retaining the structure of the metal. METALSAREDUCTILE § Metals are ductile for the same reason that the atoms of metals have the ability to move past each other without breaking the metallic bond. METALSAREGOODCONDUCTORS OFHEATANDELECTRICITY § Metals have free electrons. They conduct electricity well. MOSTMETALSAREHARD § Metals tend to be strong because of the metallic bond that keeps the atoms close together. The soft metals, on the other hand, include tin, lead, sodium, and copper. Mercury, which is liquid at room temperature, is also considered a soft metal. MOSTMETALSHAVEHIGHDENSITIES § Metals are generally dense since their atoms are closely packed together because of the strong attractive forces. Metals with low densities are sodium, lithium, cesium, and rubidium.
- 5. TWOTYPESOFMETALS FERROUSMETAL 1.are metals that consist mostly of iron and small amounts of other elements. It is prone to rusting if exposed to moisture. It can also be picked up by a magnet Commonly used examples of ferrous metals include steel, stainless steel, carbon steel, cast iron and wrought iron: a) Steel A combination of iron and carbon, steel is renowned for its strength and machinability. It is widely used in construction, manufacturing, and industrial metal fabrication. b) Stainless Steel 1dStainless steel is an alloy steel made with the addition of chromium to steel, which provides resistance against rust. It is commonly seen as kitchen accessories, cutlery, and cookware. c) Carbon Steel Carbon steel contains a high carbon content that is added to iron to create an exceptionally hard metal that is used for tools. d) Cast Iron Cast iron is a hard and wear resistant metal that is widely used for items including cookware, machine tools, engines, manhole covers and water pipes. e) Wrought Iron Unlike most other ferrous metals, wrought iron is able to resist corrosion and oxidation. It is typically used for fences, railings, and gates.
- 6. NON-FERROUSMETALS are metals that do not have any iron in them at all. This means that they are not attracted to a magnet, and they also do not rust in the same way when exposed to moisture. Commonly used non-ferrous metals include aluminum, lead, silver, brass, gold, zinc, copper, and tin: a) Aluminum Lightweight and easy to machine, shape and weld, aluminum is used for a range of applications from food cans and cookware to airplane parts and cars. b) Copper A good conductor of heat and electricity, copper is highly ductile and malleable. It is widely used for electrical wiring as well as in appliances and vehicles. c) Lead With a low melting point and low tensile strength, lead is used in electrical power cables, batteries, pipes, fuels, paint and for soldering. d) Tin Soft and malleable with a low tensile strength, tin is used as a coating to prevent steel from corroding. e) Silver Silver is used for a range of applications, including jewelry, cutlery, electrical contacts and in mirrors. f) Brass Brass is used for fixtures and fittings including taps, hooks, and doorknobs, as well as being used for light fittings and screws, among other uses. g) Gold Used for jewelry, gold also has applications including within the medical industry, in computers and also electronics. h) Zinc A medium strength metal with a low melting point, zinc is used to galvanize iron and steel to prevent rusting.
- 7. PropertiesofFerrousandNon-Ferrous MetalsComparison Ferrous and non-ferrous metals typically have differing properties, although there are some exceptions to some of these general rules: 1.Resistance to Rust and Corrosion Ferrous metals are vulnerable to rust when exposed to the elements due to their high carbon content. There are two exceptions to this rule: wrought iron resist rust due to its purity and stainless steel is protected from rust by the presence of chromium. Non-ferrous metals have a naturally higher resistance to rust and corrosion because of the lack of iron content, making them good for applications including roofing and gutters. 2. Magnetic Properties Most ferrous metals have magnetic properties. Non-ferrous metals are not magnetic.
- 8. 3. Weight Non-ferrous metals are lighter than ferrous metals. 4. Cost Non-ferrous metals tend to be more expensive than ferrous metals due to rarity, although this is not always the case. 5. Recycling Both ferrous and non-ferrous metals can be recycled. Non-ferrous metals can be recycled repeatedly as they don’t lose chemical properties or degrade during recycling. By contrast, ferrous scrap metals need to be melted, purified, and then compacted into solid blocks.
- 9. ALLOYS A metal that is normally very soft and malleable, such as aluminum, can be altered by alloying it with another soft metal, like copper. Although both metals are very soft and ductile, the resulting aluminum alloy will be much harder and stronger. Gold when combined with copper becomes suitable to make jewels. Alloy Alloys are homogeneous mixture of two or more metals. Eg. Brass, Bronze, Stainless steel. Purpose of alloying 1.To increase the hardness of the metal. 2. To increase the tensile strength of the metal. 3. To make it corrosion resistant. 4. To enhance the malleability and ductility. 5. To get attractive surface and appearance. 6. To make it abrasion resistant. 7.Melting point of the metal can be decreased. 8. The color and metallic luster can be improved. Types of alloys Alloys are classified into two types. 1.Ferrous alloys 2. Non-ferrous alloys
- 10. Ferrous alloys Alloys which contain containing iron as the main (major) constituent are called as ferrous Examples: Stainless steel, chromium steel and vanadium steel. Name of the alloy Composition Uses Stainless steel Chromium = 14% 1. Used for making kitchen utensils. Nickel = 1% 2.Used for making surgical instruments. Carbon = 1% 3.Used for making automobile parts. Iron = 84% Chromium steel Chromium = 0.5-18% 1. Used for making rock cutting machines Carbon Iron = 0.15 - 1.3% = 80.7 - 99.35% 2. Used for making files 3. Used for making ball bearings 4.Used for making connecting rods Vanadium steel Vanadium = 0.5% Chromium = 1.1- 1.5% Carbon = 0.4 - 0.5% Iron = 97.5 - 98% 1..Used for making gears and bearings 2.Used for making axles 3.Used for making springs and pistons
- 11. Name of the alloy Nichrome Composition Nickel =80% Chromium =20% s Dutch metal Copper =80% Zinc =20% Non-ferrous alloys Alloys which do not contain containing iron asthe main constituent are called asnon- ferrous alloys. Examples: Nichrome, Dutch metal, German silver, gun metal and duralumin Examples: Nichrome, Dutch metal, German silver, gun metal and duralumin Uses 1.Used in making resistance coils 2. Used for making heating elements in stoves, electric irons, water heater and toasters 1.Used for making cheap jewelry 1.Used for making musical instruments 2.Used for making battery caps 4.Used for making flexible hoses German silver Gun metal Duralumin Copper =50% Nickel =30% Zinc =20% Copper =88% Tin =10% Zinc =2% Aluminum =95% Copper =4% Magnesium =0.5% Manganese =0.5% 1. Used for makingcoins 2. Used for makingornaments 3. Used for making decorative materials 4. Used for makingbearings 5. Used for makingcoins 6. Used for makinghydraulic Fittings 7. Used in foundry works 8. Used in building aircrafts 9. Used for makingautomobile parts and locomotive parts 10.Used for makingsurgical instruments 11.Used for making cables
- 12. ·G METALLURGY Metallurgy is the branch of science and technology concerned with the properties of metals and their production and purification of metal from its ore. ·Ore - A naturally occurring solid material from which a metal or valuable mineral can be extracted. ·Flux - It is a chemical cleaning agent used for purification of ores. ·Slag - Waste matter separated from metals during the extraction of ores. angue - It is the commercially worthless/valueless material in which ore is found.
- 13. T H R E ES T E P SINM E T A L L U R G Y : 3.) Purification 1.) Concentration of Ore 2.) Isolation of metal from the concentrated Ore
- 14. Extractive Metallurgy It is the process of removing impurities or undesired materials from the ore leaving behind the required metal. 1) Pyrometallurgy- is a branch of extractive metallurgy. It consists of the thermal treatment of minerals and metallurgical ores and concentrates on bringing about physical and chemical transformations in the materials to enable recovery of valuable metals. a) Calcination – process of heating to high temperatures in the absence of air or oxygen. Its purpose is to remove volatile impurities and to remove moisture. b) Roasting – the process of strong heating of the ore in presence of excessamount of air below its melting point. Its purpose is to remove impurities like Sulfur, Arsenic and Antimony, also to remove moisture. c) Smelting – is a form of extractive metallurgy, its main use is to produce a base metal from its ore. Smelting makes use of heat and chemical reducing agent to decompose the ore, driving off other elements as gases or slag and leaving only the metal base behind. Carbon monoxide is the reducing agent for smelting.
- 15. 2.) Hydrometallurgy- is amethod for obtaining metals from their ores. It involves the use of water and other chemical compounds to obtain metals from their ores. Example: 1.) Metallurgy of tungsten Ores The main ores of tungsten are 1.Wolframite 2.Scheelite 3.Ferberite Properties Tungsten is ahard-silvery white metal. It is asheavy asgold. It has highest melting point (8377°C). Its wire is very hard and has high tensile strength. It is resistant to acids.
- 16. Uses: 1.It is used for making filaments of electric bulbs. 2.It is used for making strings for musical instruments. 3. It is mainly used for preparing special type of steels. 4. It is used for making surgical instruments. 1.) Metallurgy of titanium Ores The main ores of titanium are 1.Rutile 2.Ilmenite Properties Titanium is a shining white metal. It has low density and high melting point. It is a good conductor of heat and electricity. It has better corrosion resistance. Uses 1.It is used in aircrafts industry. 2.It is used in marine equipment. 3. It is also used for hardening steel.
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