Strange+Materials+-+Mina+Emad+Raouf

=Smart Materials = = = 
 * ==__**Shape Memory Alloys (SMA's)**__ ==
 * 1) First observed in **1938** by **Arne Olander**.
 * 2) Serious research on SMA's, started only in the **1960**'s.
 * 3) SMA's are alloys, which show two distinct and unique properties, known as : **Shape memory effect** and **Pseudo-elasticity.**
 * 4) Some of the common and widley used alloys are : **NiTi** (Nickel-Titanium), **CuZnAl** (Copper-Zinc-Aluminium) and **CuAlNi** (Copper-Aluminum-Nickel).
 * 5) The two unique properties mentioned are made through a **solid state phase change** ( A molecular rearrangment ).
 * 6) In most SMA's a **10 degrees** **celcius** is needed to initiate this phase change.
 * 7) The two phases, which occur in SMA's are: **Martensite** and **Austentite**.
 * 8) **Martensite** is the easy deformation phase of SMA's. Taking place in the lower tempratures.
 * 9) Upon deformation, it enters the second phase **Austentite** which takes place in higher tempratures.
 * 10) No change in **size** or **shape** is visible in SMA's until the **Martensite** is deformed.


 * ===//__**Shape Memory Effect**__// ===
 * 1) The effect is observed when the tempreature of a piece of SMA is cooled to below the **Mf tempreature**.
 * 2) At this stage the alloy can be easily **deformed**.(By applying a load. i.e twisting, bending, compresing).
 * 3) <span style="font-family: 'Comic Sans MS',cursive;">The orginal shape of the alloy can be recovered by **heating** above the **Af temprature**.
 * 4) <span style="font-family: 'Comic Sans MS',cursive;">The heat **rearranges** the mollecules of the alloy, maintaining it in the **solid** state.

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 * ===<span style="font-family: 'Comic Sans MS',cursive;">//__**Pseudo-elasticity Effect**__// ===
 * 1) <span style="font-family: 'Comic Sans MS',cursive;">This effect takes place when an alloy is stressed above **AF temperature** and then removed.
 * 2) <span style="font-family: 'Comic Sans MS',cursive;">The change in dimensions should **not exceed** 10% of the alloys original dimensions.
 * 3) <span style="font-family: 'Comic Sans MS',cursive;">The change occurs **without** a change in temperature.
 * 4) <span style="font-family: 'Comic Sans MS',cursive;">The alloy goes through the **elastic** deformation phase.
 * 5) <span style="font-family: 'Comic Sans MS',cursive;">Followed by entering the **plastic** deformation phase. In which materials do not go back to their original form.
 * 6) <span style="font-family: 'Comic Sans MS',cursive;">When the stress is **removed**, the alloy goes back to its original dimensions, before the stress was applied.
 * 7) <span style="font-family: 'Comic Sans MS',cursive;">Such recovery of the alloys' dimension and charectaristics is called **Pseudoelasticity.**

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 * ===<span style="font-family: 'Comic Sans MS',cursive;">//__Advantages and Disadvanteges of SMA's__// ===
 * 1) <span style="font-family: 'Comic Sans MS',cursive;">Bio-Compatibility.
 * 2) <span style="font-family: 'Comic Sans MS',cursive;">Diverse Fields of Application.
 * 3) <span style="font-family: 'Comic Sans MS',cursive;">Good Mechanical Properties ( Strong, Corrosion ressistant ).


 * ==<span style="font-family: 'Comic Sans MS',cursive;">**__Piezoelectric Materials.__** ==
 * 1) <span style="font-family: 'Comic Sans MS',cursive;">First discovered in **1880**,by the **Curie** brothers, Jacques and Pierre.
 * 2) <span style="font-family: 'Comic Sans MS',cursive;">The effect was seen on certain **crystaline minerals**.
 * 3) <span style="font-family: 'Comic Sans MS',cursive;">When subjected by a **mechanical** force (tension and compression), these crystals become **electrically** polarized, giving opposite polarities with voltages **proportional** to the applied force.
 * 4) <span style="font-family: 'Comic Sans MS',cursive;">If the effect was reversed, subjected by an electric field, the crystal changes in **dimensions** (lengthened or shortened by up to **4%** of the original volume) according to the polarity of the field and **proportional** to the force of the field.
 * 5) <span style="font-family: 'Comic Sans MS',cursive;">These effects are known as the **Piezoelectric** effect. ( From the greek word piezein meaning press or squeez )
 * 6) <span style="font-family: 'Comic Sans MS',cursive;">The **magnitude** of piezoelectric voltages, movments or forces are small. They usually need **amplification**.
 * 7) <span style="font-family: 'Comic Sans MS',cursive;">Some of the most comon piezoelectric materials are : **Quartz** (SiO2), **Berlinite** (AlPO4), **Gallium orthophosphate** (GaPO4)[|.]

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 * ===<span style="font-family: 'Comic Sans MS',cursive;">//__**Uses of piezoelectric materials[|.]**__// ===
 * 1) <span style="font-family: 'Comic Sans MS',cursive;">Piezoelectric materials are used in **varius** industries, such as: **Automotive**, **computer**, **medical**, **military** and many more.
 * 2) <span style="font-family: 'Comic Sans MS',cursive;">**Automotive**: Air bag sensor, air flow sensor, fuel atomiser seat belt buzzers.
 * 3) <span style="font-family: 'Comic Sans MS',cursive;">**Computer**: Disk drives, ink jet printers.
 * 4) <span style="font-family: 'Comic Sans MS',cursive;">**Medical**: Disposable patient monitors, ultrasonic imaging.
 * 5) <span style="font-family: 'Comic Sans MS',cursive;">**Military**: Sonar, gudiance systems, depth sounders, hydrophones.
 * 6) <span style="font-family: 'Comic Sans MS',cursive;">**Other** common uses: Cigarette lighters, jewellery cleaners, musical instruments, speakers, telephones.


 * ==<span style="font-family: 'Comic Sans MS',cursive;">//__Magnetorheological fluids (MR Fluids)__// ==
 * 1) These type of fluids possess **rheological** properties.
 * 2) These properties are **controlled**, **reversible** and **dependant** on **strength** of **magnetic field**.
 * 3) When subjected to a **magnetic** **field**, it greatly increases its apparent **viscosity** to a point where it **solidifies**.
 * 4) MR fluid particles are too **dense** for **brownian** motion.
 * 5) MR fluids contain **magnetic** particles. When a magnetic field is applied, the particles **align** themselves along the lines of **magnetic** **flux**.
 * 6) This chain of particles **restrict** the movment of the fluid, **perpendicullar** to the direction of the **flux**.



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 * ==//__Auxetic Materials.__//==
 * 1) Auxetic materials are materials with a **negative** **Poisson's** **Ratio**.
 * 2) When **stretched**, the width of auxetic materials **increases**, and vice versa. When **compressed**, the width **decreases**.
 * 3) Very few exist **naturally**, more have been **fabricated** by modifying the **microstructure** of existing materials.(i.e: **Foams** and **polymers** ).