MFGT 104 Materials and Quality Ferrous and Non-Ferrous Metals

MFGT 104Materials and QualityFerrous and Non-Ferrous Metals Professor Joe Greene CSU, CHICO MFGT 104

Ferrous and Non-Ferrous Metals • Objectives • List various ingredients of cast iron, steels, and stainless steels • Recognize and use the nomenclature associated with steels • Recognize the major regions and ranges of the iron-carbon phase diagram • List the major shapes in which ferrous metal products are available • List and describe the various alloying elements in ferrous metals and the purposes of each • Describe the process of galvanic corrosion in metals • Describe the refinement process, major alloys, uses, and properties • copper, brass, bronze, • magnesium, chromium, titanium, • lead, tin zinc, gold, and platinum • Explain the refinement process, major alloys, uses, and properties • aluminum and nickel • Describe the uses and properties of major refractory metals

Introduction • Steel was used as long ago as 2000 B.C. when charcoal was packed with iron bars and heated to 1000°C. • Steel is not an element, but an iron-carbon alloy that contains less than 2% carbon. • Cast iron contains between 2% and 4% carbon. • Wrought iron is almost pure iron that includes silicate slag. • The cementationprocess allowed the carbon in the charcoal to diffuse into the iron to produce steel in steel bars. • The crucible process improved the quality by steel bars from cementation were melted together in a large pot and poured into bars thus yielding a more uniform-quality steel

Production of Iron • Pure iron is used in limited amounts as iron ingot or iron powder. • Steels of iron and alloying elements, i.e., carbon, silicon, nickel, chromium, and manganese, are widely used. • Plain carbon steel(contains less than 1% of alloying element) • carbon, silicon, manganese • Low-alloy steel contains alloying elements that alter the properties • nickel, chromium, molybdenum • High-alloy steel contains more than 5% of alloying elements

Primary Ores • Primary ores that are refined • Magnetite: combination of ferric oxide (Fe2O3) and ferrous oxide (FeO), black in color and contains 65% iron and highly magnetic • Hematite: contains ferric oxide (Fe2O3), or rust, is red in color and contains 50% iron. • Taconite: is green in color and contains 30% iron and much silica. • Other ores that are rarely used due to low grade and yield • Limonite: hydrated ferrous oxide (FeO.H2O) • Siderite: Ferrous carbonate (FeCO3) • Iron pyrites: iron sulfides (FeS) • Earliest smelting of iron ore from charcoal (blacksmith) • carbon from wood or coal was mixed with iron ore and placed in furnace. Air was blown through mixture. • Sponge mass ,bloom, was produced that was hammered to remove impurities and slag.

Modern Practice • Modern practice- heats coal in furnace with no air. • Coking oven- furnace in which H2 and other elements are removed leaving carbon in the form of coke. • Blast furnace- cleaned iron ore is layered with coke and limestone. Slag is removed with other impurities after the metal is tapped from the furnace. Limestone is used as a blast furnace slag to remove impurities as sulfur and silica. • Process • Air is blown at the bottom of the furnace at 1100°F so that the carbon in the coke reacts with the oxygen in the ore and starts to burn of the oxygen from the iron oxides. The T increases from the reaction to 3000°F. • After 5 to 6 hours, the iron is tapped from the furnace and poured into ingots • Each ingot (pig) weighs one ton and has 4% carbon as in cast iron. • For other steels, alloying elements are added after remelting. • Production rate of 3000 tons of pig iron a day would require • 6,000 tons of iron ore and 3,000 tons of coke. • 1,500 tons of limestone and 90,000 ft3/min of hot air

Continuous Process Shapes • Steel can be formed into many shapes • hot rolled at 2200 F is used to form shapes • cold rolled (formed after cooling) or cold drawing at room temperature is used to finish thin, flat products • Common shapes • Angles with legs of equal (8x8in) or unequal lengths (9x4in) • Bars of solid shape cold or hot drawn from 0.75 to 12 in thick • Beams as in standard I and H beams • Billets with section of ingot suitable for rolling • Blooms as in slabs of steel with equal widths and depths • Channels of a U-shape in cross section • Plates: large flat slabs thicker than 0.25 in • Sheets: large flat slab thinner than 0.25 in • Tubing: square, rectangular and round tubing and pipe • Wires: drawn from bars that have been rolled to small diameters

Carbon Content in Steels • Carbon is the most important alloying element in steel. • Most steels contain less than 1% carbon. • Plain carbon steel- carbon is the only significant alloying element • Mild steel, or low carbon steel, are produced in the greatest quantity because it is cheap, soft, ductile, and readily welded. Caution: it can not be heat-treated • Mild steels are used for car bodies, appliances, bridges, tanks, and pipe.

Carbon Content in Steels • Medium carbon steel - used for reinforcing bars in concrete, farm implements, tool gears and shafts, as well as uses in the automobile and aircraft industries. • High carbon steels - used for knives, files, machine tooling, hammers, chisels, axes, etc. • A small increase in carbon has significant impact on properties of the steel. As Carbon increases the steel: • becomes more expensive to produce • becomes less ductile, i.e., more brittle • becomes harder • becomes less machinable • becomes easier to harden and harder to weld • has higher tensile strength • has a lower melting point

Cold Working in Steels • Cold working is used to enhance the properties of steel • Reducing thickness by 4% raises the tensile strength by 50% • Cold working is plastic deformation at room temperature. • Cold working produces dislocations in the metal’s structure which block dislocations as they slide along the slip planes • Products • Cold-rolled sheet steel • Cold drawn tubing • Drawbacks • higher leads are required to size the material as the yield strength increases • work-hardening occurs wherein the material becomes harder • heat treating can reduce the drawbacks

Other Elements in Steels • Alloying elements are added to nullify undesirable elements • Carbon • Manganese • increases strength, malleability, hardenability, and hardness • Sulfur reacts with the Mn which reduces the hot short effect of the iron sulfide accumulating at the grain boundaries and reducing strength at Temp • Aluminum- • reacts with Oxygen versus iron (no sparks). Killed steel • promotes smaller grain size which adds toughness • Silicon- reduces Oxygen negative effects • Boron- increases the hardenability of steel (only with Al added) • Copper- increases corrosion resistance • Chromium- increases corrosion resistance and hardenability • Nickel, Niobium, titanium, tungsten carbide, vanadium • increase toughness and strength and impact resistance

Nomenclature in Steels • SAE and AISI developed method of cataloging steel based on • carbon content- % carbon with implied decimal • alloying elements • AISI 8620 steel is the same as SAE 8620 steel • Steels are usually 4 digit designations • 1018 steel = 10 is plain carbon steel; 18 represents 0.18% carbon • 4030 steel = 40 is molybdenum steel of .15% to 0.30% Molybdenum and 0.30% carbon • 2 - - - = nickel steel with % nickel, 22-- is nickel with 2% nickel • 10100 = five digits indicated 1% carbon more • B in the middle of the number, 81B40 indicates min of 0.0005% boron • Various common steels • 1010: Steel tuning; 1040: Connecting rods for automobiles • 4140: Sockets and socket wrenches;52100: Ball and roller bearings • 8620: Shafts, gears, and machinery parts.

Tool Steels • Tool steels are special types of steel produced to make tooling to cut or shape other materials • Produced by electric furnace • Typically, hardened and vary from high carbon to high alloy • Have high wear and heat resistance, high strength, good hardenability • Alloying elements include Chromium (Cr), Cobalt (Co), Copper (Cu), Manganese (Mn), Molybdenum (Mb), Nickel (Ni), Silicon (Si), Tungsten (W), and Vanadium (V) • Tool Steel Classification • A: Air- Hardening, medium-alloy steel • H: Hot working steels. Forging equipment. • M: High speed steels, containing molybdenum. Lathe tools, drills • O: Oil-hardening, low alloy steels • S: Shock-resisting, medium-carbon, low-alloy steels. Hammers. • T: High-speed steels containing tungsten. • Contain 0.75%C, 18%W, 4%Cr, 1%V • W: Water-hardening, high-carbon steels. W-1 plain carbon with 1%C

Cast Iron • Other ferrous metals include • cast iron (gray-3.5% carbon and >1% silicone and white- 2.5 - 3.5% carbon and 0.5 - 1.5% silicon. ) • ductile cast iron • malleable cast iron • wrought iron • Steel with >2% iron is cast iron because of the lack of ductility. • Carbon in form of graphite (gray) or iron carbide (white) • Grey cast iron has no ductility and will crack if heated or cooled too quickly. • Grey cast iron has good compression strength, machinability, vibration damping characteristics • Grey used for furnace doors, machine bases, and crackshafts • White cast iron has good wear resistance and is used in rolling and crunching equipment

Cast Iron • Nodular or ductile cast iron is possible with the additions of calcium, cerium, lithium, manganese, or sodium in 0.05% • Causes nodules (small balls or spheres instead of flat plates) or spherulites to form if metal is allowed to cool slowly. • This removes stress risers in ordinary cast iron. • Ductile cast iron contains 4% Carbon and 2.5% Silicon • Ductile iron is used for engine blocks, machine parts, etc. • Maleable cast irons are heat treated versions of white cast iron. • Cast iron with 2 to 3% Carbon is heated to 1750F, where iron carbide or cementite is allowed to form spherulites. Similar to ductile cast iron • Pearlitic malleable iron- heated to 1770F and quenched cooled • Ferritic malleable iron- heated to 1770F and air cooled • Special heat treated process gives malleable cast irons with min elongation of 10% to 20%

Stainless Steel • Definition and Applications • Alloys that posses unusual resistance to attack by corrosive media • Applications include aircraft, railway cars, trucks, trailers,... • AISI developed a 3digit numbering system for stainless steels • 200 series: Austenitic- Iron-Cr-Ni-Mn • Hardenable only by cold working and nonmagnetic • 300 series: Austenitic- Iron-Cr-Ni • Hardenable only by cold working and nonmagnetic • General purpose alloy is type 304 (S30400) • 400 series: • Ferritic- Iron-Cr alloy are not hardenable by heat treatment or cold working • Type 430 (S43000) is a general purpose alloy • Martensitic- Iron-Cr alloys are hardenable by heat treatment and magnetic • Type 410 (S41000) is a general purpose alloy

Stainless Steel • Corrosion of steels can be slowed with addition of Cr and Ni. • Stainless steels have chromium (up to 12%) and Ni (optional) • ferritic stainless: 12% to 25% Cr and 0.1% to 0.35% Carbon • ferritic up to melting temp and thus can not form the hard martensitic steel. • can be strengthened by work hardening • very formable makes it good for jewelry, decorations, utensils, trim • austenitic stainless: 16% to 26% Cr, 6% to 23% Ni, <0.15% Carbon • nonmagnetic and low strength % to 25% Cr and 0.1% to 0.35% Carbon • machinable and weldable, but not heat-treatable • used for chemical processing equipment, food utensils, architectural items • martensitic stainless: 6% to 18% Cr, up to 2% Ni, and 0.1% to 1.5% C • hardened by rapid cooling (quenching) from austenitic range. • Corrosion resistance, low machinability/weldability used for knives, cutlery. • Marging (high strength) steels: 18% to 25% Ni, 7% Co, with others • heated and air cooled cycle with cold rolled • Machinable used for large structures, e.g., buildings, bridges, aircraft

Stainless Steel • AISI developed a 3 digit numbering system for stainless steels • 200 and 300 series: Austenitic • 400 series: Ferritic and martensitic

Corrosion • Ferrous metals rust because the iron reacts with oxygen to form iron oxide or rust. Process is corrosion • Corrosion occurs as well when metal is in contact with water and metal ions dissolved in water. • Galvanic corrosion: electrochemical process which erodes the anode. • Metals in galvanic series: the further apart the worse the corrosion • Magnesium- most positive or anodic. Gives up electrons easily and corrodes • Aluminum • Zinc • Iron • Steel • Cast Iron • Lead Brass • Copper • Bronze • Nickel • Stainless steel • Silver • Graphite

Introduction • Nonferrous metals are those that do not contain iron • Many nonferrous metals are used in modern products • Radioactive metals • uranium, thorium, plutonium as nuclear fuels. • zirconium is an alloying element and as a nuclear fuel. • Light metals • aluminum, beryllium, titanium as structural metals • calcium, lithium, magnesium, potassium, are used to extract metals from their ores because they are too chemically reactive and too soft • sodium and potassium are used in nuclear field as coolants • Heavy metals • Nickel and lead are used in many versatile applications • Copper is used for electrical and thermal applications • Cadmium, tin, and zinc are used in electrical applications and bearings • Cobalt and manganese are used as alloying elements for ferrous and non ferrous • Silver is used as a decorative and as a brazing alloy • Gold, silver, and platinum are used for electrical contacts and jewelry • Refractory metals (melt point > 3600F) • Columbium, titanium, tungsten, vanadium, and zirconium for high T, strength, hardness

Aluminum • Aluminum is one of the most abundant elements in the earth’s crust • third to oxygen and silicon • 8% of any clay is alumina, pure aluminum oxide (Al2O3). • Extraction costs are lower for bauxite ore (Al2O3*3H20), hydrated aluminum ore. • Aluminum History • Aluminum discovered in 1825 by Hans Oested • Extraction process used reaction with sodium metal was very expensive. • Costs were $500 per pound. Royalty uses. • Charles Hall(1886) produced aluminum using electrolysis. • HallMethod involves the electrolysis of a molten solution of alumina in cryolite or sodium aluminum fluoride at temperatures around 1745 F. • Once in solution the Al separates by electrolysis. • Hall founded the Aluminum Company of America (ALCOA) • Bauxite first found near French town of Le Baux • Cost is as low as $0.15 per pound. Automotive is $1.50 per pound

Aluminum Extraction • Majority of Bauxite in the US comes from Surinam, Jamaica, Guyana • Bauxite has iron oxides and other impurities. • Iron oxide difficult to remove since Al is very active metal, it will not react with the Carbon as do iron and copper to reduce the oxide. • Steps in Aluminum production • Ore is crushed and washed and then dried. • Dried powder is mixed with with soda ash (NaCO3), lime (CaO), and water to form sodium aluminate (Na2Al2O4) • Effluent is filtered and then precipitated to yield aluminum hydrate [AlO(OH)] • Solution is heated to 2000F to form aluminum oxide (Al2O3) at 99.6% purity • Aluminum oxide is electrolyzed using Hall Method by placing in a container with cryolite at 1800F. • Large carbon electrodes are lowered into the molten solution, and a large direct current is applied (around 1000,000A). Electrodes are positively charged whereas the lining of the container is the negative electrode. • Metallic aluminum is drawn off the bottom of the container and cast into ingots. • Aluminum is 99.5% to 99.8% pure with impurities being iron, manganese, and silicon.

Aluminum Properties • Properties • Corrosion resistant, • Lightweight • Conductivity of 60% that of copper. Per pound conductivity is 2 x Cu • Low strength can be improved with alloys • FCC structure enables Al to be ductile and easily shaped. • Attracts oxygen since it is chemically active. • Aluminum oxide is dull-gray and it sticks to the aluminum providing a protection. • Anodizing of aluminum • Anode of aluminum is placed in an electroplating cell with oxalic, sulfuric, or chromatic acid as the plating solution or electrolyte. • Current is applied to the solution causing the anode to be plated with a hard, wear resistance surface. • Anodized coatings give the aluminum better appearance and may be colorized

Wrought Aluminum Numbering System • Wrought Numbering System • Aluminum Association developed system for cast and wrought Al • Wrought aluminum- 4 digit system, e.g. 2011 • first digit represents alloying elements in the alloy • second digit represents alloy modifications or degree of control of impurities • third digit represents arbitrary numbers that indicate a specific alloy or indicate the purity of the alloy over 90% • fourth digit represents same as third digit

Wrought Aluminum Numbering System • Common aluminum alloys • Silicon alloys used for castings • Copper alloys used for machining • Magnesium alloys used for welding • Pure aluminum used for forming • Magnesium and silicon alloys used for extrusion • Copper alloys used for strength • Examples • 2011 with 5% to 6% copper is a free machining alloy • 2024 contains between 3.8% and 4.9% copper with 1.5% magnesium. This alloy is heat treatable aluminum alloy that is commonly used for aircraft parts. • 3003 has 1% to 1.5% manganese which provides additional strength • 4043 contains 4.5% to 6% silicon and is used in welding wire • 5154 contains 3.1% to 3.9% magnesium and is weldable and available in sheets, plates, and many structural shapes. • 6063 contains approximately 0.5% magnesium and silicon and is used in windows, doors, and trim

Casting Aluminum Numbering System • Casting Numbering System • Cast aluminum- 3 digit system that is not generally standardized • Aluminum Association developed system for cast • silicon casting alloys up to 99 • silicon copper from 100 to 199 • magnesium from 200 to 299 • silicon manganese from 300 to 399 • Applications • Good conductor for electrical and electronics applications • Light weight good for structural applications that require medium strength and light weight. • High reflectivity for infrared and visible radiation make it desirable for headlights, light fixtures, and insulations • Flake form is used for pigment • Cast Al engine blocks and pistons

Casting Aluminum Heat Treatment • Heat treatment • Internal structure of Al can be modified with heat treatment • Number system for heat treatment follows alloy designation • Only copper, zinc and magnesium-silicon alloys can be age hardened • Wrought alloys are not heat-treatable are given either an O (annealed) suffux or an F (as-fabricated). Others are as follows

Chromium • Cr discovered in 1797 by Dr. Louis Vauguelin, Prof. of Chemistry at the College of France • Named for its colorful nature • Chromic oxide, Cr2O3, has a dark green color • Potassium chromate, KCrO4, is bright yellow • Potassium dichromate, K2Cr2O7, is orange, • Chromium trioxide is red, • Lead chromate, PbCrO4, is yellow. • Chromium is the third hardest element to Boron and Diamond • It is extremely resistant to corrosion and is often used as a corrosion resistant alloy or as a plating material. • Primary Chromium ore is chromite (FeOCr2O3), typically found in Albania, Russia, Rhodesia, Turkey, and Iran • Reduction Process of Chromium (Most Cr is used in alloy form) • Grinding and crushing ore to powder • Reacted with powdered Al to release iron and chromium • Refined by electrolysis to obtain pure chromium (not always desired)

Chromium Uses • Alloy for ferrous materials, e.g., HS steel, stainless steels, and other metals, e.g., Ni alloys, refractories, and bronzes • Plating material providing a hard, corrosion-resistant surface over other materials. • Chromium will not stick to steel very well but will adhere to Nickel • Triple plating process is used to plate steels • Steel is degreased and cleaned well, • Etched with nitric acid to roughen the surface of the steel, • Thin layer of copper is added to steel, then washed • Thin layer of nickel is added to copper then washed, • Final layer of chromium is added to nickel via Chromic acid. • Coating thickness of 0.0002 inch provide shiny decorative finish • Coating thickness of 0.05 inch provide wear resistance.

Copper, Brass, and Bronze • Copper is one of the oldest metals- used by early civilizations • Copper is FCC • Copper ores are found close to the earth’s surface as • oxide (cuprite) • sulfide (chalcopyrites, bornite, chalconite, and covellite) • carbonate (malachite and azurite) • silicate form (chrysocolla) • Copper properties • high thermal is 10 times that of steel, useful for chill, casting molds • melting point is 1981 F (however, oxides form when Cu is exposed to heat or environmental conditions thus surface treatments are needed. • electrical conductivity requires relatively pure copper • Silver, cadmium, and gold can be added to increase strength without significantly reducing conductivity

Copper Applications • Copper and Copper alloys are used for tubing and pipe and in heat transfer applications. • Copper compounds are toxic and thus not used in food-related • Copper Alloys • brass: alloy of copper and zinc • bronze: alloy copper and elements other than zinc • Copper is very useful in electrical applications • A large percentage of Copper produced is used in electrical and electronic industries. • At very low temps (absolute zero), Cu becomes a superconductor. • Superconductors have very low resistance to current flow. • A current started in a superconductor will flow almost indefinitely. • Magnetic Resonance Imaging (MRI) devices used in hospitals for diagnosing patients are examples of superconductivity. • Future uses may include magnetic levitation (Mag-lev) trains being prototyped in Japan today.

Copper Smelting Process • Copper Smelting Process • Copper ores are cleaned in a floatation process to remove silica (sand), aluminum oxide (clays), and other unwanted materials. • Floatation process • grind ores into powder and place in water. • foaming agent (soap) is added, creates a froth, brings the copper ore to surface. • Ore is skimmed off leaving undesirable materials in the water. • Concentrated ore is roasted in an oven to convert iron sulfides to iron oxides and contains copper oxides, copper sulfides, iron sulfates, silicates, and other impurities. • Ores are placed in smelting furnace and melted at 2600 F. • Melted ore is called matte copper, containing 30% copper. • Mixture placed in a converter with a flux (silica), air is blown through • Sulfur is oxidized and removed from the melt by Sulfur dioxide bubbling through the ore leaving blister copper. • Copper is 98% to 99% pure. • Slag drawn off t he mixture is further refined to extract other Au, Ag.

Copper Electrical Wire Production • Copper Electroplating • Small amounts of impurities reduces conductivity of the copper. • Impurities removed by electroplating • Blister copper is remelted and cast into plates called anodes (+). Refined copper cathodes (-) are placed on the other side in staggered pairs (figure below) • Plates are immersed in plating solution of copper sulfate. • Anode connected to Positive and cathode to Negative terminal of direct current. • When current is applied, the metal in the anode goes into solution and the copper is plated on the cathode. Impurities in anode metal are left in the solution • Plating on cathode will be 99.9% pure copper. • Copper used in electrical wire is remelted using an oxidizing flame to prevent sulfur from being reabsorbed into the copper and keep oxygen less than 0.04%, called electrolytic tough pitch (ETP) copper. • Phosphorous is added to control the amount of oxygen in copper, oxygen-free high conductivity (OFHC) or phosphorous deoxidized (DHP) copper.

Copper Alloys • Copper alloys are among the oldest of metallic alloys • Alloying elements increase strength,hardness, machinability, appearance, and cost • Melting points of copper alloys are lower than that of pure copper. • Alloying elements • Aluminum, beryllium, lead, manganese, • Nickel, phosphorous, silicon, tin, and zinc • Brass: copper-zinc alloy • Zinc is added to increase strength, improve ductility, and improve machinability • Bronze: copper-tin alloy • Tin is added to improve strength, hardness, and ductility; reduce cost • Names, compositions, and typical uses of copper alloys • There are more alloying elements in brasses than copper and zinc alone. • Brass and bronze are multi-component systems and have a phase diagram

Copper-Zn Phase Diagrams • Phase Diagram for Copper Zinc • There are more alloying elements in brasses than copper and zinc alone. • Brass and bronze are multi-component systems and have a phase diagram. • Alfa brasses: up to 36% Zn can dissolve in Copper and form one phase. FCC • Beta phase is BCC • Alfa + Beta is 38% to 46% Zn • Brass Varieties: Yellow & Red • Red • less alloy better corrosion • most ductile and malleable

Copper-Tin Phase Diagrams • Phase Diagram for Copper-Tin • Bronze refers to metal alloys containing copper with any other metal • Traditionally copper and tin • Phosphorous added to improve ductility: phosphor bronzes (1% to 11% P) • Red Bronzes contain more than 90% copper • Al bronzes are heat treatable and highest strength bronzes. Uses structural • Si bronzes are high strength alloys of Cu and Ni. Uses in tubing as per resistance to attack from fresh and salt water • Be bronzes (<2% Be) are heat treatable and highest strength copper alloy. Non-sparking when struck by another metal. Uses with explosives. • Nickel bronzes named Nickel silver and German Silver used for coins • Present dimes and quarters are 75% Cu and 25% Ni clad over and inner core of copper

Magnesium • Magnesium discovered 1808 by Sir Davy is the lightest of the structural metals • Mg weighs 66% as much as Al. • Derived from sea water. 1 lb of Mg from 100 gal of sea water. • Mg is hexagonal-closed pack in structure like most light meals. • Process • seawater is filtered through lime [Ca(OH)2] and oyster shells, which converts the Mg to Mg hydroxide and precipitates out of the water • HCl acid is added to convert MG hydroxide to Mg Cl • After drying, electrolysis decomposes the MgCl into Mg metal and chlorine gas • The Cl gas is recycled to HCl acid and Mg is drawn off. • Mg is active metal and was used first in incendiary bombs due to it burning with extremely hot flame, giving off intense heat. • Mg chips are readily ignitable making it dangerous to gas weld. • Mg used as anodes for protecting water tanks, piping, etc. • Mg used as alloy is ferrous metals, e.g., ductile cast iron.

Nickel • Nickel closely resembles steel in many properties • Nickel is used for 5 cent coin, 75% Cu and 25 % Ni • Nickel supplied by Canada, Russia, and Australia in the form (FeNi)9S8 and pyrrhorite (iron sulfide with nickel) • Processing • Mond Process • Carbon monoxide gas is washed and heated over ore which converts Ni to nickel carbonyl, which is very volatile. • It turns from solid to gas at temperatures above 1783 F. • Decomposition decomposes it into metallic nickel and carbon monoxide. • Extraction process similar to copper • Ni ore is mined, crushed, and ground, washed, and concentrated by floatation • Ore is roasted and smelted in an electric furnace to produce matte • Matte is placed in converter, where air is blown through metal to produce blister • Blister Ni is remelted and cast into anodes, which are refined with electrolysis • Ni is placed on cathodes which is removed for fabrication or used as alloy

Precious Metals • Precious Metals due to value and use in jewelry and coinage. • Gold, silver, and platinum. • Limited applications in industry • Gold (FCC structure) • Found as nuggets, dust, and in quartz rock (reacted with mercury or cyanide. • Most gold comes from South Africa • Properties include electrical conductivity, corrosion resistance, and malleability. • Applications include plating material via electroplating from AuCl, dental work as caps, crowns, and fillings. [Dental gold alloys are 70% gold, 5% platinum, 5% palladium, 25% silver, 18% copper, 3% nickel, 1% zinc. • Alloys of gold necessary because of inherent softness, Cu, Ni, and platinum. • Purities are given in carat scale. 24 carat is pure gold. 12 carat is 50%

Precious Metals • Silver (Ag, Latin argentum) FCC structure • Occurs in nature in argentite (Ag2S) and horn silver (AgCl). • Properties: excellent malleability and ductility. • Applications: • US coins until 1964. Replaced by Nickel silver and copper. • Plating other metals as electrical conductors and jewelry. • Light sensitive compounds for photographic materials. • Approx. 30% of all silver goes toward photographic films and papers. • Photochromic (light sensitive) lenses for glasses which darken when exposed to light • Brazing alloys and silver-cadmium batteries. • Explosives as silver fulminate. • Ointments, salves, and creams for medical purposes. • Gold and silver sold as Troy ounce, where there are 12 oz. to pound.

Precious Metals • Platinum (FCC structure) • Platinum group contains 6 metals which are extracted from nickel ores • Includes iridium, osmium, palladium, rhodium, and ruthenium • All six have high melting points, > 3000F • Found in nature in the mineral sperrylite (PtAs2) • Applications: • corrosion resistant coatings and as a catalyst for many reactions. • High resistance wire for furnaces • Used in catalytic converters in automobiles, where it converts unburned hydrocarbons and carbon monoxide to carbon dioxide and water. • Laboratory equipment, medical instruments, fine jewelry. • Disadvantage is cost, Pt is more expensive than gold

MFGT 104 Materials and Quality Ferrous and Non-Ferrous Metals