Teknologi Dan Rekayasa PROPRIETIES OF METALS

I CAN I can define the terms associated with metal and metal fabrication. I can explain metal classification. I can list the major characteristics of ferrous metal, nonferrous metal and alloys I can identify types of metals by the way of the spark test. I can identify the different ways marking and cutting metal. Teknologi dan Rekayasa

PROPRIETIES 1. Solid at room temperature. Most metals are solid at room temperatures (one notableexception is mercury). Solid means having a definite shape and volume. 2.  Opaque Metal will not permit light to pass through it. Even very thin sheets of metal cannot be penetrated by ordinary light. 3.  Conductor of heat and electricity. All metals are conductors because they have electrons, which are free to move about. This property of metals is very important and widely used. (Gold, silver, aluminum and copper are very good conductors.) Teknologi dan Rekayasa

PROPRIETIES 4. Luster All metal seems to reflect light when polished. 5.  Crystalline structure Upon examination under a microscope, a metal is found to be made up of small grains. These grains (crystals) vary in shape and size. The arrangement of the atom (small particles within the grains) determine the shape of the crystalline structure. 6.  Expansion and contraction Metal expand when heated and contract when cooled. This is due to the spacing of the atoms within each grain of metal. 7.  Hardness This is the ability of a material to resist indentation, penetration, abrasion and scratching. Metals vary in hardness. Carbon content and application of heat will affect hardness. Teknologi dan Rekayasa

PROPRIETIES 8. Magnetism This is important property in metals. Metals that are attracted to a magnet are most of the ferrous metal, nickel and cobalt. 9.  Ductile Metals have the ability to become permanently deformed without cracking or failing. Many metals have this property such as aluminum and copper. 10. Malleable The metal have the ability to be hammered or rolled into various shapes. 11.High specific gravity— Specific gravity is the ratio of the mass of a certain substance to that of an equal volume of water. In most cases metals have a higher specific gravity than water.   Teknologi dan Rekayasa

CHEMICAL PROPERTIES Metal will combine with other elements such as oxygen, sulfur and the halogens. Iron has a special affinity for carbon. They are electropositive in character (due to the tendency to lose electrons) They are present as cations (positively charge, taken in) when their salts are dissolved in water. Whenever metals are fused together or by some means chemically combine at their point of contact by a process like welding, a sharing of electrons take place. The outer ring is not full in the electron, then atoms of two different elements, or two of the same come together to fill the outer ring. If the outer ring is fill, than there is no sharing of electrons like inert gases like argon Teknologi dan Rekayasa

TERMINOLOGY OF METALS 1. Adhesion The sticking together of two unlike metals involving a mechanical bond. The mechanical bond involves the flowing of a metal in a liquid form into the pores of a metal in a solid form. Brazing and soldering are examples of adhesion. 2. Alloy A mixture of two or more metals or metals and one or more non- metals. 3. Annealing Softening metal and removing the brittleness. This is done by heating the metal to a cherry-red color and allowing it to cool slowly in vermiculite or dry hot sand. Teknologi dan Rekayasa

TERMINOLOGY OF METALS 4. Carbon An element (symbol C), nonmetal often mixed with iron. 5.   Casting In metalwork, pouring metal into a mold, so that after cooling it will be certain shape or form. 6.   Cementite The compound iron carbide (Fe3C) which is quite hard and brittle. It is iron with carbon dissolved in it. 7.    Ferrite Elemental iron which is usually very soft. It is only slightly harder that copper in a body centered cubic lattice composed of nine atoms. Examples are auto fenders and parts of soft drink cans. Teknologi dan Rekayasa

TERMINOLOGY OF METALS 8. Fusion The mixing of molten metals. 9. Grains Most similar crystals closely packed together in standard symmetric pattern. 10.  Hardening Making steel harder. This is done by heating the medium or high carbon steel to a cheery red color and cooling it quickly in water. Hardened steel is not only extremely hard but also brittle. Hardening is the first step in tempering. 11.  Hardness The ability of a metal to resist denting. Teknologi dan Rekayasa

TERMINOLOGY OF METALS 12. Heat A type of energy. It is stored as molecular motion within a substance. Heat always mover from a substance of high heat content towards a substance of low heat content. 13.  Iron A crystalline metallic element. Symbol Fe. 14.  Lattice The fundamental geometric structure of the crystals. The three types of lattices found in iron are body-centered- cubic, face- centered-cubic and hexagonal. The body- centered-cubic is composed of 9 atoms. The face- centered-cubic is composed of 14 atoms. The hexagonal lattice is composed of 17 atoms. Teknologi dan Rekayasa

TERMINOLOGY OF METALS 15. Melting point The point at which a metal starts to change from solid to liquid. 16.  Tempering Obtaining the desired hardness and toughness in metal. The degree of hardness, brittleness or toughness is determine by the job expected of the steel.  17. Toughness The resistance to fracture after permanent deformation. Teknologi dan Rekayasa

CLASSIFICATION OF METALS Ferrous Metal : Metals whose chief ingredient is iron. Non-Ferrous Metal : Metals which have no iron and made up of single elements Ferrous Alloys : Metal made up largely of ferrous materials but have other elements in sufficient quantities to change the ferrous characteristics. Non-Ferrous Alloys : Metals that are made up of two or more non-ferrous elements. Teknologi dan Rekayasa

Ferrous Metal Pig iron (Mine from soil) Cast iron Wrought Iron Steel low carbon steel medium carbon steel high carbon steel (Drill bits) Teknologi dan Rekayasa

NON-FERROUS METALS Aluminum Copper Lead Magnesium Nickel Tin Tungsten Zinc Silver Gold Teknologi dan Rekayasa

FERROUS ALLOY METAL Manganese steel Chrome steel Nickel steel Stainless steel Tungsten steel Molybdenum steel Vanadium steel Silicon steel Aluminum steel Phosphorus steel Teknologi dan Rekayasa

Non-Ferrous Alloy Metals Brass Bronze Solder Mixing of tin & lead Melting point is lower. Pewter Teknologi dan Rekayasa

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