Sherri C Rukes Libertyville High School AACT President elect Materials Matter Sherri C Rukes Libertyville High School AACT President elect

AACT American Association of Chemistry Teachers Teachchemistry.org Webinars Resources Lessons Videos Simulations Networking

Polymer Ambassadors www.polymerambassadors.org Mission Statement: The Polymer Ambassadors, with resources from educational, industrial, and professional societies, promote polymer education with teachers, students, and community audiences.

Polymer Awards Excellence in Polymer Education High School Teachers TAPE (Teaching Award for Polymer Education) K – 8 Teachers Sponsored by American Chemical Society divisions: IPEC Deadline for applications: May 15th www.Polymerambassadors.org

Polymer Grants Ten will be awarded each year K – 12 Teachers Up to $250 for supplies Email me for the application – will soon be on the Polymer Ambassador site Sponsored by American Chemical Society divisions: IPEC www.polymerambassadors.org

Materials Science Teacher Camps Sponsored by ASM International Foundation http://asmcommunity.asminternational.org One week in the summer Solids, metals, ceramics/glass, polymers, composites Labs, demos, practical applications No cost Over 40 locations across the country

Chemistry

Material Science

Materials Changing 1903 – Wright brothers in Kitty Hawk NC take flight 1969 – Neil Armstrong walks on the moon 1984 – 1994 the Brick phone – Moterola DynaTAC 1992 – first smartphone 2007 – mini computer smartphones – iPhone

Materials Science is about… Understanding and developing a greater appreciation for the importance of the variety of materials in our lives Studying how materials can be changed or manipulated The search for new materials Composition Structure Performance Processing 10

Materials I.D. Lab Free write – everything you know about the following categories: Metal Ceramic/Glass Polymer Composite Separate the item into the categories above. List the reason you placed it into that category. If others don’t agree with you, they can send you to another group

Materials ID Lab History Free-Write Which category has been used by mankind the longest? Why that particular one? What did they use it for?

Stuff: The Materials the World is Made Of by Ivan Amato

Materials ID Lab PART II If you were to take apart a mechanical pencil, predict how many different pieces you would find. What kind of materials do you think would be used? Now take the mechanical pencil apart and determine what materials were used in the making of this item.

Categorize the materials you found. Why was each material chosen Categorize the materials you found. Why was each material chosen? How was each piece manufactured?

Types of matter: element, compound, mixture   Types of matter: element, compound, mixture Types of elements: metals, nonmetals, metalloids / semimetals Types of structure: crystalline, amorphous Types of bonding: metallic, ionic, covalent, intermolecular forces metals ceramics/glass polymers element or mixture compound or mixture of mostly compounds compounds metallic elements metals & nonmetals or nonmetals metalloids & nonmetals crystalline ceramics = crystalline mostly amorphous w/ glass = amorphous regions of crystallinity metallic bonding ionic bonding and covalent bonding with network covalent bonding weak intermolecular forces

Metals

Crystalline vs Amorphous Bb board

Crystal Structure Why do we care about a crystal structure of a particular metal? The question to think about -how workable is the metal. Huh???? Changing the shape of the solid without cracking or breaking it. In Chemistry we call it……………….

Models of Crystals Lab Look for spacing (tightly vs. loosely packed – “gappiness”) Look for relative number of slip planes Try combining several examples of the same model into a bigger one

Type of crystal structure Closely packed? Many slip planes? Workability Simple cubic FCC BCC HCP

Hexagonal close packed Simple cubic Face-centered cubic (FCC) Body-centered cubic (BCC) Hexagonal close packed (HCP) Show examples

Type of crystal structure Closely packed? Many slip planes? Workability Simple cubic No Yes FCC BCC HCP

Type of crystal structure Closely packed? Many slip planes? Workability Simple cubic No yes FCC Yes BCC HCP

Workability Which crystal structure is more workable? Many slip planes or few slip planes? Tightly packed or loosely packed? (more or less “gappiness”?) Chalk demo Ice tray demo

Ice Cube trays Going over a bridge scenario Chalk on a piece of wood - toy

Type of crystal structure Closely packed? Many slip planes? Workability FCC Yes Highest BCC No Middle HCP Least Use samples of the various metals to have students figure out which is the most and next most.

Crystal Structures & Metals BCC FCC HCP Other Chromium Aluminum Cobalt Manganese Iron < Calcium Magnesium Tin Molybdenum Copper Titanium Sodium Gold Zinc Tungsten Iron > Lead Nickel Platinum Silver

Iron Wire Demo

Summary of observations made by students Heat makes metals expand (thermal expansion) Metals can get hot enough to give off light (incandescence) Heat increases the rate of oxidation (rusting) Ferrous metals lose magnetism at a certain temperature - Curie temperature is 770°C Solid state phase change occurred at 912°C. This was observed as a "dip' (bounce) by the wire as it was contracting while cooling.

Explanations by Structure Iron at room temperature is BCC - more spread out Iron above 910 ⁰ C is FCC - closer packed Dip was caused by changing from FCC to BCC at 912⁰C

Point Defects Substitutional Interstitial Vacancy

Line Defects - Dislocations

BB Boards

Copper Wire Activity

Work Hardening rolling coins drawing wires

Heat Treating Steel Lab 1. Set aside one bobby pin and one paperclip for controls (A).   2. Heat one of each red hot and slowly lift out of flame. Slow cool. Anneal. (B) 3. Heat 2 of each red hot and quench in ice water. Quench. (C) 4. Take one of each from step #3 and heat again in the top of the flame until a blue color appears on the metal. Do NOT let it get red hot. Slow cool or quench. This is called tempering. (D) 5. Make a data table for comparison of properties when the heat-treated area is bent.

WORK HARDENING- to strengthen a material by reshaping it while the part is cold FORGING- shape or form metal by beating or hammering it ANNEALING - heat to red hot, air cool - metal is heated and cooled so that crystal can reform. - softens metal by relieving stress QUENCHING/ HARDENING - heat to red hot, quench in cool water - rapid cooling of metal (in water or oil) locks atoms into place in an unstable crystal structure - strengthens metal but brittle TEMPERING - heat to red hot, quench, re-heat to blue, air cool - heating material so atoms re-orient themselves - removes brittleness but keeps strength Heat Treating Terms

NiTinol Nitinol is a shape memory alloy that exhibits a solid state phase change with interesting and useful properties. Ni = nickel Ti = titanium NOL = Naval Ordnance Laboratory Straighten or deform a piece of shape memory metal. Dip the distorted wire into a beaker of water at approximately 70°C (or higher based on which alloy you have). It will return to its original “trained” shape. Test different samples and shapes. A hair dryer may also be used as a source of heat. Hold the metal in the warm water using pliers on each end. Deform the metal and release the wire from one of the pliers – it will be elastic and not pliable. Straighten or attempt to deform a piece of super-elastic metal. It springs back to its original shape. Dip the super-elastic metal into a dry ice/ethanol bath and immediately straighten or deform the metal upon removal – it will now relax and deform. It will return to its original shape as it warms in the air. A solid state phase change occurs at a specific transition temperature. A crystal structure change occurs – more pliable structure at cooler temperatures and an elastic structure at warmer temperatures. By varying the percentages of nickel and titanium in the alloy, different transition temperatures can be achieved. Shape memory wire - transition above room temperature Super-elastic wire - transition below room temperature The “set” shape of a piece of nitinol can be changed by using a heat treatment around 500°C.

The term nitinol is derived from its composition and its place of discovery: (Nickel Titanium-Naval Ordnance Laboratory). William J. Buehler[1] along with Frederick Wang,[2] discovered its properties during research at the Naval Ordnance Laboratory in 1959.[3][4] Buehler was attempting to make a better missile nose cone, which could resist fatigue, heat and the force of impact. Having found that a 1:1 alloy of nickel and titanium could do the job, in 1961 he presented a sample at a laboratory management meeting. The sample, folded up like an accordion, was passed around and flexed by the participants. One of them applied heat from his pipe lighter to the sample and, to everyone's surprise, the accordion-shaped strip stretched and took its previous shape.[5] While the potential applications for nitinol were realized immediately, practical efforts to commercialize the alloy did not take place until a decade later. This delay was largely because of the extraordinary difficulty of melting, processing and machining the alloy. Even these efforts encountered financial challenges that were not readily overcome until the 1990s, when these practical difficulties finally began to be resolved. The discovery of the shape-memory effect in general dates back to 1932, when Swedish chemist Arne Ölander[6] first observed the property in gold-cadmium alloys. The same effect was observed in Cu-Zn (brass) in the early 1950s Nitinol's unusual properties are derived from a reversible solid-state phase transformation known as a martensitic transformation, between two different martensite crystal phases, requiring 10,000–20,000 psi (69–138 MPa) of mechanical stress. At high temperatures, nitinol assumes an interpenetrating simple cubic structure referred to as austenite (also known as the parent phase). At low temperatures, nitinol spontaneously transforms to a more complicated body-centered tetragonalcrystal structure known as martensite (daughter phase). The temperature at which austenite transforms to martensite is generally referred to as the transformation temperature. More specifically, there are four transition temperatures. When the alloy is fully austenite, martensite begins to form as the alloy cools at the so-called martensite start, or Ms temperature, and the temperature at which the transformation is complete is called the martensite finish, or Mf temperature. When the alloy is fully martensite and is subjected to heating, austenite starts to form at the As temperature, and finishes at the Af temperature.[8] Thermal hysteresis of nitinol's phase transformation The cooling/heating cycle shows thermal hysteresis. The hysteresis width depends on the precise nitinol composition and processing. Its typical value is a temperature range spanning about 20-50 K (20-50 °C; 36-90 °F). Crucial to nitinol properties are two key aspects of this phase transformation. First is that the transformation is "reversible", meaning that heating above the transformation temperature will revert the crystal structure to the simpler austenite phase. The second key point is that the transformation in both directions is instantaneous. Martensite's crystal structure (known as a monoclinic, or B19' structure) has the unique ability to undergo limited deformation in some ways without breaking atomic bonds. This type of deformation is known as twinning, which consists of the rearrangement of atomic planes without causing slip, or permanent deformation. It is able to undergo about 6–8% strain in this manner. When martensite is reverted to austenite by heating, the original austenitic structure is restored, regardless of whether the martensite phase was deformed. Thus the name "shape memory" refers to the fact that the shape of the high temperature austenite phase is "remembered," even though the alloy is severely deformed at a lower temperature.[9] 2D view of nitinol's crystalline structure during cooling/heating cycle A great deal of pressure can be produced by preventing the reversion of deformed martensite to austenite — from 35,000 psi to, in many cases, more than 100,000 psi (689 MPa). One of the reasons that nitinol works so hard to return its original shape is that it is not just an ordinary metal alloy, but what is known as an intermetallic compound. In an ordinary alloy, the constituents are randomly positioned on the crystal lattice; in an ordered intermetallic compound, the atoms (in this case, nickel and titanium) have very specific locations in the lattice.[10] The fact that nitinol is an intermetallic is largely responsible for the difficulty in fabricating devices made from the alloy. The effect of nitinol composition on the Ms temperature. The scenario described above (cooling austenite to form martensite, deforming the martensite, then heating to revert to austenite, thus returning the original, undeformed shape) is known as the thermal shape memory effect. To fix the original "parent shape," the alloy must be held in position and heated to about 500 °C (932 °F). A second effect, called superelasticity or pseudoelasticity, is also observed in nitinol. This effect is the direct result of the fact that martensite can be formed by applying a stress as well as by cooling. Thus in a certain temperature range, one can apply a stress to austenite, causing martensite to form while at the same time changing shape. In this case, as soon as the stress is removed, the nitinol will spontaneously return to its original shape. In this mode of use, nitinol behaves like a super spring, possessing an elastic range 10–30 times greater than that of a normal spring material. There are, however, constraints: the effect is only observed about 0-40 K (0-40 °C; 0-72 °F) above the Aftemperature. Nitinol is typically composed of approximately 50 to 51% nickel by atomic percent (55 to 56% weight percent).[10][11] Making small changes in the composition can change the transition temperature of the alloy significantly. One can control the Aftemperature in nitinol to some extent, but convenient superelastic temperature ranges are from about −20 °C to +60 °C. One often-encountered complication regarding nitinol is the so-called R-phase. The R-phase is another martensitic phase that competes with the martensite phase mentioned above. Because it does not offer the large memory effects of the martensite phase, it is, more often than not, an annoyance.