Chemistry of Engineering Materials (Metals) PDF

BATAAN HEROES COLLEGE Module 4.1 CHEMISTRY OF ENGINEERING MATERIALS (METALS) CHEMISTRY FOR ENGINEERS GILLIAN ROSE R. SALVADOR, LPT General Education Department CHEMISTRY FOR ENGINEERS/MODULE 4.1 GILLIAN ROSE R. SALVADOR, LPT Page 0  BATAAN HEROES COL...

BATAAN HEROES COLLEGE Module 4.1 CHEMISTRY OF ENGINEERING MATERIALS (METALS) CHEMISTRY FOR ENGINEERS GILLIAN ROSE R. SALVADOR, LPT General Education Department CHEMISTRY FOR ENGINEERS/MODULE 4.1 GILLIAN ROSE R. SALVADOR, LPT Page 0  BATAAN HEROES COLLEGE Module 4.2: Chemistry of Engineering Materials (Metals) Module Description This module discusses the chemistry of metals as an engineering material. Objectives of the Module: At the end of this module the students should be able to: 1. Examine the advantages of metals as engineering materials; 2. Differentiate the metal production processes; 3. Classify types metals and their applications; 4. Assess the disadvantages of metals; and 5. Explain the concept of corrosion and ways to prevent it. 4.2.1. Metals ✓ one of the most important engineering materials ✓ Inorganic materials composed of metallic elements 4.2.2. Advantages of Metals as Engineering Materials A. High stiffness and strength ✓ can be alloyed for high rigidity, strength, and hardness B. Toughness ✓ capacity to absorb energy better than other classes of materials C. Good electrical conductivity ✓ Metals are good conductors of electricity D. Good thermal conductivity ✓ conduct heat better than ceramics or polymers CHEMISTRY FOR ENGINEERS/MODULE 4.1 GILLIAN ROSE R. SALVADOR, LPT Page 1  BATAAN HEROES COLLEGE E. Cost ✓ the price of steel is very competitive with other engineering materials 4.2.3. Metal Production A. Mining ✓ process of removing the metal in its free or combined state from the Earth's surface B. Purification ✓ process to separate the ore from waste materials such as rocks sand and clay with which it occurs ✓ Example: Froth Flotation- used with ores of copper, zinc, and some other metals (ore is turned into powder, mixed with water and pine oil then air is introduced to produce Froth Flotation bubbles and froth, impurities settle and metal Source: Eddy Pump Corp., 2020 is adsorbed by pine oil and float to the top) C. Reduction ✓ metals always occur in their oxidized state in ores, often as the oxide or sulfide of the metal. In order to convert an ore to its elemental state, therefore, it must be reduced ✓ Example: Blast Furnace- cylindrical vessel into which is fed iron ore with a temperature of more than 1000˚C (carbon reacts with oxygen forming carbon dioxide that reacts with the oxides of iron to produce pure iron Blast Furnace Source: Seefeldt, 2019 metal) CHEMISTRY FOR ENGINEERS/MODULE 4.1 GILLIAN ROSE R. SALVADOR, LPT Page 2  BATAAN HEROES COLLEGE 4.2.4. Classification of Metals A. Ferrous ✓ those based on iron ✓ Strongest materials available ✓ Used for applications where high strength is required at relatively low cost and where weight is not of primary importance ✓ Principal raw material for all ferrous metals is pig iron which is obtained by smelting iron ore with coke and limestone, in the blast Classification of Ferrous Metals furnace Source: Mahmood, 2014 B. Nonferrous ✓ all other metals ✓ Pure metals are rarely used as structural materials as they lack mechanical strength ✓ Used where their special properties such as corrosion resistance, electrical conductivity and thermal conductivity are required ✓ Mainly used with other metals to improve their strength. ✓ Examples: Aluminum, magnesium, copper, nickel, titanium, zinc, lead, tin, molybdenum, tungsten, gold, silver, platinum, and others Alloy- a mixture or compound of two or more elements, at least one of which is metallic Alloying- Increase strength, hardness, and other properties compared to pure metals 4.2.5. Ferrous Metals Alloys A. Steel Source: Wu, n.d. ✓ alloys of iron and carbon, containing up to 1.5 % of carbon ✓ Applications: chemical pressure vessels, building construction, and machine parts CHEMISTRY FOR ENGINEERS/MODULE 4.1 GILLIAN ROSE R. SALVADOR, LPT Page 3  BATAAN HEROES COLLEGE ✓ Stainless Steel- alloying element is chromium, usually greater than 15% - forms a thin impervious oxide film that protects surface from corrosion Agitator/Pressure Vessel (Stainless Steel) Source: Zibo Fumin Chemical Equipment Co. Ltd, n.d. B. Cast Iron ✓ obtained by re-melting pig iron with coke and limestone in a furnace known as cupola ✓ Alloy of iron and carbon, containing 1.7% to 4.5% carbon ✓ Low cost, good casting characteristics, high compressive strength, wear resistance and excellent machinability ✓ Types of Cast Iron 1. Grey Cast Iron - ordinary commercial iron - Grey colour is due to the fact that the carbon is present in the form of free graphite - Free graphite in its structure acts as a lubricant and is very suitable for those parts where sliding action is desired - Applications: machine tool bodies, automotive cylinder Star Grip (Grey Cast blocks, heads, housings, fly-wheels, pipes and pipe fittings Iron) Source: Liaoning Borui and agricultural implements. Machinery Co., Ltd., n.d. 2. White Cast Iron - white colour is due to fact that it has no graphite and whole of the carbon is in the form of carbide (known as cementite) which is the hardest constituent of iron CHEMISTRY FOR ENGINEERS/MODULE 4.1 GILLIAN ROSE R. SALVADOR, LPT Page 4  BATAAN HEROES COLLEGE - Hard and cannot be machined with ordinary cutting tools but requires grinding as shaping process 3. Malleable Cast Iron - ductile and may be bent without breaking or White Cast Iron fracturing the section - Tensile strength usually higher than that of grey cast iron and has excellent machining qualities - Applications: machine parts for which the steel forgings would be too expensive for a fair degree of accuracy, e.g. brake supports, parts of Malleable Cast Iron agricultural machinery, pipe fittings, door hinges, Source: Anupoju, 2016 locks, etc 4. Alloy Cast Iron - produced by adding alloying elements like nickel, chromium, molybdenum, copper and manganese in sufficient quantities - Has special properties like increased strength, high wear resistance, corrosion resistance or heat resistance Alloy Cast Iron - Applications: gears, automobile parts like Source: Indian Metal Cast, n.d. cylinders, pistons, piston rings, crank cases, crankshafts, camshafts, sprockets, wheels, pulleys, brake drums and shoes, parts of crushing and grinding machinery CHEMISTRY FOR ENGINEERS/MODULE 4.1 GILLIAN ROSE R. SALVADOR, LPT Page 5  BATAAN HEROES COLLEGE C. Wrought Iron ✓ purest iron which contains at least 99.5% iron but may contain up to 99.9% iron ✓ Tough, malleable and ductile material ✓ Can be easily forged or welded ✓ Applications: chains, crane hooks, railway couplings, water and steam pipes Wrought Iron Source: Kate, 2020 Classification of Non-Ferrous Metals Source: Mahmood, 2014 CHEMISTRY FOR ENGINEERS/MODULE 4.1 GILLIAN ROSE R. SALVADOR, LPT Page 6  BATAAN HEROES COLLEGE 4.2.6. Non-Ferrous Metals A. Aluminum ✓ white metal produced by electrical processes from its oxide (alumina), which is prepared from a clay mineral called bauxite ✓ Hard and rigid when upon addition of other alloys ✓ Can be formed, drawn, turned, cast, forged and die cast ✓ Has good electrical conductivity and high resistance to Aluminum Source: earth.com, 2018 corrosion ✓ It is relatively lighter and non-toxic ✓ Applications: Overhead cables, cooking utensils, food wrap, aircraft and automobile components B. Copper ✓ soft, malleable and ductile material with a reddish-brown appearance ✓ A good conductor of electricity ✓ Applications: electric cables and wires for electric machinery and appliances, in electrotyping and electroplating, in making coins and household utensils. ✓ Two Groups of Copper Alloys 1. Brass- Copper (50%)-zinc(50%) alloy 2. Bronze- Copper-tin alloy Copper, Brass, & Bronze - composition is 75 to 95% copper and 5 to 25% Source: Metal Supermarket, 2015 tin C. Lead ✓ bluish grey metal and is so soft that it can be cut with a knife ✓ Applications: lining for acid tanks, water pipes, and as Lead coating for electrical cables. Source: Wahab, 2020 D. Tin CHEMISTRY FOR ENGINEERS/MODULE 4.1 GILLIAN ROSE R. SALVADOR, LPT Page 7  BATAAN HEROES COLLEGE ✓ brightly shining white metal and is soft, malleable and ductile ✓ It can be rolled into very thin sheets. ✓ Applications: fine solder, as a protective coating for iron and steel sheets and for making tin foil used as moisture Tin Cans proof packing Source: Seahath Canning Company, n.d. 4.2.7. Disadvantages of Metals A. Prone to corrosion B. Relatively costly than thermoplastics C. Design limitations D. Production causes pollution 4.2.8. Corrosion ✓ the deterioration of materials by chemical interaction with their environment ✓ Most metals corrode on contact with water (and moisture in the air), acids, bases, and salts ✓ Metals will also corrode when exposed to gaseous materials like acid vapors, formaldehyde gas, ammonia gas, and sulfur containing gases. ✓ Happens through a series of reduction-oxidation reactions ✓ Metal being corroded acts as the anode; the metal is oxidized, forming metal ions and free electrons. The free electrons reduce the oxygen, often times forming hydroxide, and providing a complimentary cathodic reaction 𝐹𝑒(𝑂𝐻)3 dehydrates to form 𝐹𝑒2 𝑂3 ∙ 𝑛𝐻2 𝑂 Corrosion Process Source: Souza, 2014 CHEMISTRY FOR ENGINEERS/MODULE 4.1 GILLIAN ROSE R. SALVADOR, LPT Page 8  BATAAN HEROES COLLEGE A. Some Ways to Prevent Corrosion of Metals 1. Painting ✓ forms a barrier between the metal and the environment 2. Sacrificial Anode ✓ utilization of a metal lower on the Galvanic Series to be attacked first, instead of the metal in use Review Questions Instruction: Using the module as your guide, answer the following questions: 1. As the engineer in-charge, you are tasked to design equipment that is lightweight and less prone to corrosion. What type of metal (ferrous or non-ferrous) will you use? Why? ______________________________________________________________________ ______________________________________________________________________ 2. Which among the three types of ferrous metals (steel, cast iron, and wrought iron) is the hardest? Why? ______________________________________________________________________ ______________________________________________________________________ 3. What type of cast iron is best suited for making accurate machine parts? ______________________________________________________________________ ______________________________________________________________________ 4. Why is the production of metal causes environmental pollution? ______________________________________________________________________ ______________________________________________________________________ 5. Is corrosion physical change or chemical change? Why? ______________________________________________________________________ ______________________________________________________________________ Answers to Review Questions CHEMISTRY FOR ENGINEERS/MODULE 4.1 GILLIAN ROSE R. SALVADOR, LPT Page 9  BATAAN HEROES COLLEGE 1. As the engineer in-charge, non-ferrous metal should be used to design equipment that is lightweight and less prone to corrosion since ferrous metal is relatively heavier and more prone to corrosion. 2. Among the three types of ferrous metals, cast iron is the hardest because it contains the highest amount of carbon- 1.7-4.5% (component that makes the metal hard). 3. Malleable cast iron is best suited for making accurate machine parts because of its good machining qualities. 4. The production of metal causes environmental pollution due to its by-products and due to its high- heat requirement. 5. Corrosion is a form of chemical change since metals undergo chemical processes (reduction-oxidation) and irreversible change (rust cannot be transformed again into metal). CHEMISTRY FOR ENGINEERS/MODULE 4.1 GILLIAN ROSE R. SALVADOR, LPT Page 10  BATAAN HEROES COLLEGE Assessment Instruction: Using the table below, list down five (5) household objects with different uses that are made of metals. Identify whether they are ferrous or non-ferrous. On the third column, explain why it is advantageous to use metals instead of other material for that object. OBJECT TYPE OF METAL ADVANTAGE e.g. Cutleries (spoon & Ferrous (Stainless steel) It is not breakable like glass and it fork) can be used multiple times unlike plastics. 1. 2. 3. 4. 5. CHEMISTRY FOR ENGINEERS/MODULE 4.1 GILLIAN ROSE R. SALVADOR, LPT Page 11  BATAAN HEROES COLLEGE References Anupoju, S. (2016). Cast Iron as a Building Material- Manufacturing, Types, Properties and Applications. Retrieved from Cast Iron as a Building Material- Manufacturing, Types, Properties and Applications Earth.com. (2018). What is Aluminum? Retrieved from https://www.earth.com/earthpedia- articles/aluminum/ Eddy Pump Corporation. (2020). Froth Pumps - Froth Flotation Pumping for Mining, Paper/Pulp, and Wastewater. Retrieved from https://eddypump.com/education/froth-pumps-froth- flotation-pumping/ Indian Metal Cast. (n.d.). Alloy Cast Iron Casting. Retrieved from https://www.indiamart.com/proddetail/alloy-cast-iron-casting-10575680673.html Kate, P. (2020). What are the Different Styles of Wrought Iron Design? Retrieved from https://www.wisegeek.com/what-are-the-different-styles-of-wrought-iron-design.htm Liaoning Borui Machinery Co., Ltd. (n.d.). Why is Grey Cast Iron So Popular? Properties and Uses. Retrieved from http://www.metals-china.com/why-is-grey-cast-iron-so-popular- properties-and-uses.html Metal Supermarket. (2015). Difference Between Copper, Brass And Bronze. Retrieved from https://www.metalsupermarkets.com/difference-between-copper-brass-bronze/ Mahmood, S. (2014). Engineering Materials. Retrieved from https://www.academia.edu/5682956/Engineering_Materials Seahath Canning Company. (n.d.). Tinplate Silver Food Tin Can OTS, Size: 425. Retrieved from https://www.indiamart.com/proddetail/food-tin-can-ots-15963479091.html Seefeldt, J. (2019). The Importance of Metallurgical Slags and Their Evaluation. Retrieved from https://www.thermofisher.com/blog/materials/the-importance-of-metallurgical-slags-and- their-evaluation/ Souza, C. (2014). Degradation and surface engineering. Retrieved from https://cauesantos14.wordpress.com/2014/12/20/laboratory/ Wahab, A. (2020). Lead. Retrieved from https://science4fun.info/lead/ Wu, J. (n.d.). About Precious Metal Alloys. Retrieved from https://joycewustudio.com/en/faqs/precious-metal-alloys/ CHEMISTRY FOR ENGINEERS/MODULE 4.1 GILLIAN ROSE R. SALVADOR, LPT Page 12  BATAAN HEROES COLLEGE Zibo Fumin Chemical Equipment Co. Ltd. (n.d.). Agitator/Pressure Vessel, Made of Stainless Steel. Retrieved from https://www.globalsources.com/si/AS/Zibo- Fumin/6008845417115/pdtl/Agitator-Pressure-Vessel/1072375707.htm CHEMISTRY FOR ENGINEERS/MODULE 4.1 GILLIAN ROSE R. SALVADOR, LPT Page 13