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Materials Science and Engineering

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Presentation on theme: "Materials Science and Engineering"— Presentation transcript:

1 Materials Science and Engineering

2 What is a Material Engineer?
Material engineers develop and test new materials for various uses that help us create a wide range of new products such as Computer chips Recreational equipment (i.e. golf clubs, bicycles, skis, etc.) Building materials for cars, aircraft, etc. Building materials for houses, skyscrapers, and bridges

3 What are materials? Materials are made of one or more substances.
A single substance material is a pure substance, while a material composed of several substances is classified as a mixture. Pure substances are created through chemical changes; mixtures are created through physical changes. All materials have unique physical and chemical properties that make them suitable for one application or another.

4 Slime is a Unique Material
Slime is a unique POLYMER because it has qualities of both a solid and a liquid. It can take the shape of its containers like a liquid does, yet you can hold it in your hand and pick it up like a solid. As you might know, solid molecules are tight together, liquid molecules spread out and break apart (drops). As you will soon learn, POLYMER molecules CHAIN themselves together (they can stretch and bend like chains) and that gives them flexibility. Jell-O, rubber bands, plastic soda bottles, sneaker soles, even gum are all forms of polymers. The polymer you made should be kept in a sealed plastic bag when you aren't playing with it. Also, be sure to keep it away from young kids or pets who might think it's food. Have fun!

5 Matter All materials are made of matter.
Matter: anything that takes up space and has mass Mass: the amount of “stuff” in an object Weight: gravity’s pull on mass on Earth, this is the same as mass Law of Conservation of Matter: “matter cannot be created or destroyed”…but it can be rearranged (via chemical or physical reactions, the same as energy)

6 Atoms Matter is composed of atoms
Atoms: The smallest piece of an element that still retains the properties of that element can not be further divided and still have those properties Are composed of protons, neutrons, and electrons

7 Pure Substance A substance with uniform and constant composition (set formula) Ex: H2, Cl2, C6H12O6, NaCl, H2O, Fe Elements and compounds are both considered to be pure substances

8 What is an Element? Element: A substance that can not be changed into a simpler substance(s) under normal laboratory conditions A substance made up of only one type of atom is an elemental substance Material engineers are working on the process of creating man-made diamonds to be used as superconductors in electronics. Because diamonds are made of only the element carbon, they are considered a pure substance.

9 How do we represent the elements?
Represented by symbols on the periodic table Usually comes from the name, a person, or a place One or two letters for those with official names First letter is always capitalized Second letter is never capitalized Unofficially named elements have three letters, starting with a capital U

10 The Periodic Table A highly organized arrangement of the elements

11 Metals Are solids at room temperature (with the exception of mercury)
Conduct heat and electricity Malleable- can be hammered or pounded into shapes without breaking Have a luster, or shine Combine with other metals to make mixtures called alloys (more on alloys later)

12 Non-metals Mostly gases at room temperature in elemental form
Poor conductors of heat and electricity (insulators) Combine chemically with other non-metals to make non-metallic compounds

13 Semi-metals AKA metalloids
Have properties of both __________________________ Semi-metals at the _____________ of the table are more like non-metals Semi-metals at the _____________ of the table are more like metals

14 The Periodic Table allows us to predict what type of material an element is.

15 What is a compound? Compound: A substance composed of two or more elements in fixed proportions that cannot be broken down into simpler substances by physical means.

16 Compounds Two (2) or more DIFFERENT elements combined in definite proportions Has own, unique: Formula properties Boiling point, freezing point, density, etc Need a chemical reaction to separate them into the elements it is made from 2 H2O -> 2H2 and O2

17 Properties of Compounds
properties differ from those of individual elements under the same conditions EX: table salt (NaCl) Na is a metal Cl2 is a gas Ex: water (H2O) H2 is a gas O2 also a gas

18 How do we represent compounds?
Chemical formulas show us not only the elements that make up a compound, but also show us the ratio in which those elements combine. Examples: NaCl, H2O, C6H12O6 Synthetic (man-made) Rubber is a material composed of compounds formed between carbon and hydrogen. When carbon and hydrogen bond together, the compounds they form have completely different properties than either elemental carbon or elemental hydrogen.

19 Element, Compound, or Mixture?
Vitamin C (C6H8O6) Water Orange juice Iron Steel (iron and carbon) Diamond Concrete Pryex (silicon dioxide and boric oxide)

20 All materials have unique physical and chemical properties
Physical Property Characteristic of a substance that can be observed without changing the identity (formula) of the substance Examples: state of matter density color melting pt. odor boiling pt.

21 All materials have unique physical and chemical properties
Chemical Property Ability of a substance to change to a different substance You must change the identity (formula) of the substance to observe a chemical property Examples: flammability reactivity with acids and bases

22 Materials undergo Physical Changes
A physical change is a change in the form of the substance, not in its chemical nature No chemical bonds broken or made The chemical formula is the same before and after the change The attractions between the molecules are made or broken, not the molecules themselves Examples: cutting/tearing change in state: melting, boiling, evaporating, condensing, freezing bending

23 Materials undergo Chemical Changes
Change one substance into another Atoms are reorganized to make new substances Bonds are broken and reformed in new ways Examples: Burning Mixing baking soda and vinegar Digestion Rusting

24 Signs of Chemical Change
Change in: Bubbling/ fizzing color temperature Hot (exothermic) Cold (endothermic) odor giving off light

25 Materials can also be mixtures of several pure substances
A mixture is a blend of 2 or more pure substances Have variable compositions No chemical formula If the substances mixed together are only metals, the mixture is called an alloy. Examples: Steel is a mixture of carbon and iron Bronze is an alloy of copper and tin

26 Classification of Matter

27 How Stuff Works: Steel Steel is a very useful building material. Describe why steel is such a special material. How can the properties of steel be altered? Where does steel come from? Why is the recycling process so important to the steel industry?

28 Alloys Created by a mixture of two or more metals
Why do materials engineers use alloys? Some alloys are stronger than the individual metal ingredients Mixing metals results in a substance with altered properties Changing density - an engineer can make a material that is lighter or heavier Changing flexibility - an engineer can make a material that is more or less rigid Cost savings (i.e. 14-k gold is less expensive than 18-k gold) Disadvantages of alloys Requires a tremendous amount of energy to make – mixing metals requires that the metals are molten at the time of mixing Processing creates a lot of pollution and toxic waste products Prone to corrosion, so protective coatings are required More on Alloys:

29 Polymers Polymers are made of long, chemically bonded chains of atoms.
Usually made of carbon and hydrogen that can be linked in many different ways to make many different types of polymers Plastics are a type of polymer that are processed by molding and shaping and come in many different types (i.e. polyethylene and nylon) Why do materials engineers use polymers? Polymers are durable – they do not rust or degrade Polymers are flexible They can be molded into almost any shape They can be colored during production, so there is no need to paint They are recyclable Disadvantages of polymers Difficult to produce uniformly Contaminated easily during production by even a tiny bit of dirt Any variation in heat or molding time can ruin production More on polymers:

30 True or False: What do you think?
Polymers are only man-made. Spider silk is stronger than steel. Scientists created nylon while trying reproduce spider silk in the laboratory. A recycled plastic bottle is only recycled into other bottles.

31 Composites Made of two or more different materials with distinctly different physical and chemical properties which remain separate in the finished material Doesn’t that mean a composite material is a mixture? NO! A mixture results when the components are uniformly mixed together. The materials of a composite are not uniformly mixed together. Why do materials engineers use composites? Have properties that cannot be achieved by any one material alone Composites materials have a high strength-to-weight ratio Corrosion resistant Disadvantages of composites Expensive to make Difficult to repair if damaged because they cannot be reshaped More on Composites:

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