Presentation Transcript

1. Introduction to Materials

2. What Are Materials? Substances out of which all things are made Currently the MatWeb Material Property Data website lists over 76,000 individually unique materials http://www.matweb.com What materials are present in the classroom?

3. MaterialHistory Throughout history cultures have been defined by their ability to select and modify materials. Can you think of a time in America when material availability played a critical role in defining culture? Is American culture currently being defined by availability and demand for materials?

4. MaterialHistory Materials continue to change the world. Advancements in materials, technology, andscience create continued advancement possibilities for each sector. TechnologyAdvancements ScienceAdvancements MaterialsAdvancements

5. MaterialComposition What makes a material? Elements Consist of only one type of particle or atom Cannot be broken down Criteria for element classification Based on individual properties Grouped according to shared properties Amount of substance is irrelevant

6. MaterialComposition Elements Nonmetals Metalloids Metals Classification of Elements Divided into three categories based on Physical Properties – Boiling point, melting point, density, color, hardness, and texture Chemical Properties – Reactivity to acid, oxygen, and flammability

7. MaterialComposition Metal Elements Distinguishing Characteristics Good conductors of heat and electricity, hard, shiny, reflect light, malleable, ductile, typically have one to three valence electrons

8. MaterialComposition Nonmetal Elements Distinguishing Characteristics Most are gases at room temperature Solids are dull, brittle, and powdery; electrons are tightly attracted and restricted to one atom; poor conductors of heat and electricity

9. MaterialComposition Metalloids Distinguishing Characteristics Possess both metallic and nonmetallic properties

10. MaterialComposition Compounds Most substances are compounds Compounds are created when two or more elements are chemically combined Properties are different than the elements from which the compound was created

11. MaterialComposition Compounds Element combinations are not random but based upon specific mass ratios, such as H2O = 1 g of hydrogen to 8 g of oxygen Compounds can only be broken down through chemical processes, not physical processes

12. MaterialComposition Mixtures Non-chemical combination of any two or more substances Elements within the mixture retain their identity Mixtures do not have a definite ratio Mixtures can be physically separated

13. MaterialClassification Based upon material composition and distinguishable properties Metallic Materials Ceramic Materials Organic Materials Polymeric Materials Composite Materials Common material classification categories:

14. MetallicMaterials Distinguishing Characteristics Pure metal elements (Not commonly found or used) Metal element compounds (alloy)(Commonly used due to the engineered properties of the compound) Thermal and electrical conductors Mechanical properties include strength and plasticity

15. Ceramic Materials Distinguishing Characteristics Compounds consisting of metal and nonmetal elements Thermal and electrical insulators Mechanical properties include high strength at high temperatures and brittleness

16. CeramicMaterials Applications Clay—Shaped, dried, and fired inorganic material Examples: Brick, tile, sewer pipe, chimney flue, china, porcelain, etc. Refractory—Designed to provide acceptable mechanical or chemical properties while at high temperatures Example: Space shuttle all-silica insulating tiles

17. CeramicMaterials Applications Electrical Resistors—Create desired voltage drops and limit current Thermistors—Application of heat regulates current flow Rectifiers—Allow current to flow in one direction Heating elements for furnaces

18. OrganicMaterials Distinguishing Characteristics Are or were once living organisms Consist of mostly carbon and hydrogen Genetically alterable Renewable Sustainable

19. PolymericMaterials Distinguishing Characteristics Compounds consist of mostly organic elements Low density Mechanical properties include flexibility and elasticity Polymeric Subgroups Plastics Elastomers

20. PolymericMaterials Plastics Thermoplastic Formed into a desired shape by applying heat and pressure and being cooled May be heated and remolded Thermosetting Formed into a desired shape by applying heat and pressure and being cooled May not be heated and remolded

21. PolymericMaterials Elastomers Natural or synthetic material Can be stretched 200 percent of their length at room temperature and can return quickly to original length after force is released Vulcanization Chemical process used to form strong bonds between adjacent polymers to produce a tough, strong, hard rubber (automobile tires)

22. CompositeMaterials Distinguishing Characteristics Composed of more than one material Designed to obtain desirable properties from each individual material

23. CompositeMaterials Layer Composites—Alternate layers of materials bonded together Particulate Composites—Discrete particles of one material surrounded by a matrix of another material Fiber-Reinforced Composites—Composed of continuous or discontinuous fibers embedded in a matrix of another material

24. MaterialSelection Material selection is based upon application, required material properties, and budget. Applications can vary from electrical components to construction of large-scale civil engineering projects. Initial material property considerations consist of product function, environmental conditions, and material degradation.

25. MaterialSelection Refined material selection based upon: Technical and structural analysis Examination of known and desired properties, such as: Mechanical Thermal Electromagnetic Chemical

26. MaterialSelection Mechanical Properties Deformation and fracture as a response to applied mechanical forces Strength Hardness Ductility Stiffness

27. MaterialSelection Thermal Properties Affected by heat fluxes and temperature changes Thermal Capacity—Heat storage capacity of a material Thermal Conductivity—Capacity of a material to transport heat Thermal Expansion—How a material expands or contracts if the temperature is raised or lowered

28. MaterialSelection Electrical Properties Material response to electromagnetic fields Electrical Conductivity—Insulators, dielectrics, semiconductors, semimetals, conductors, superconductors Thermoelectric—Electrical stimuli provoke thermo responses; thermo stimuli provoke electrical responses

29. MaterialSelection Chemical Properties Response and impact of environment on material structures Oxidation and Reduction—Occur in corrosion and combustion Toxicity—The damaging effect a material has on other materials Flammability—The ability of a material to ignite and combust

30. MaterialSelection—Alternative Material selection and development is currently focused on alternative materials. Alternative materials are being designed to solve socioeconomic problems such as sustained economic development and depletion of natural resources. Alternative materials include Fullerenes Liquid Crystals Biocompatible Materials Microelectronics