Materials 10pt Questions

List at least two benefits and two cons of having a high draw ratio in melt spinning

List at least two benefits and two cons of having a high draw ratio in melt spinning

Pros: Better mechanical properties
Higher crystallinity and orientation

Cons: Chance of breakage
Uneven surfaces or properties

AmXp structure with coordination # 8=fluorite structure

Explain how piezoelectricity was implemented in sonar, then list 3 other items that use piezoelectricity which effect they experience.

A charge is passed into the piezoelectric material causing it to emit a high frequency sound wave(converse effect). The wave is then reflected off whatever it hits and sent back to the piezoelectric material which sends an electrical signal to the computer which displays what is below(direct effect). 

1. A lighter uses the direct piezoelectric effect to produce a spark when the button is pressed that ignites the gas.

2. A buzzer uses the converse piezoelectric effect to cause a vibration of the desired frequency.

3. Telescope arrays use the converse effect to make precise adjustments to account for atmospheric distortion.

Name three techniques that can be used to identify a metal or alloy. 

LIBS 

OES  

XRF

XRD

XPS

You want to manufacture 10,000 ball valves a month using a CNC machine. Decide which copper alloy you will use for this task. Give an approximate ratio of each component. Explain why you chose your alloy.

I would choose to use brass as it is easier to machine and cheaper due to the zinc content. Furthermore, I would use red brass as it is more commonly used in valves and fittings due to its higher strength compared to yellow brass. I would add lead or bismuth to the brass in order to decrease the wear on my CNC machine as well as friction inside the valve thanks to the lead precipitation effect. My final ratio would be ~92:8 copper:zinc in the brass component, and then 97:3 brass:lead. 

Explain what intercalation is. Give an example of how intercalation of Graphite is used.

Intercalation is the process by which molecules, ions, or atoms are inserted between the layers of a host material

1. Battery Technology 

   1.  anode 

2. Energy Storage

   1. supercapacitors & sodium-ion batteries 

3. Catalysts

   1. organic synthesis & environmental remediation 

4. Gas Storage & Separation

   1. gas sensors & gas purification 

5. Electrochemical Sensors

Compare amalgam and composite dental filling materials, give at least 3 differences.

1)While Amalgam is an alloy of mercury with another metal, composite is a bis-GMA resin along with filler materials, such as powdered glass.

2)Amalgam fillings are not aesthetically pleasing, and have a metallic look on the teeth, whereas composite ones are natural tooth color.

3)Unlike amalgam fillings, composite fillings bond with the remaining tooth enamel. As a result, composite fillings are less likely to fracture even though they have less inherent strength than amalgam fillings.

4) Amalgam fillings expand with age and can crack the tooth itself. By contrast, composite fillings shrink and are more likely simply to fall out.

What is the significance of the Shape-Memory-Effect of a Nitinol vascular stent? What occurs within the nitinol that causes the shape-memory-effect to take place?

The shape-memory-effect is what causes the stent to reopen the artery that has narrowed. What causes this effect is the reversible phase transformation that nitinol goes through. When manufactured, the nitinol starts in a FCC structure similar to austenite. It is cooled and goes through a transformation to a BCC structure like martensite. While it is in this BCC structure  it is crimped to fit inside of the delivery device as it is easily shaped while in this BCC structure. When the delivery device  is inserted into the body, the nitinol begins going through the reverse phase transformation from a BCC structure back to an FCC structure. This causes the nitinol to reestablish its original shape from before it was crimped, opening up the narrowed artery. 

For colored multiuse plastic bottles, such as the ones below, was the coloration produced from a dye or pigment? How do you know?

It was likely produced from a dye because the bottles are transparent and uniform in color.

There is an accelerated aging study being done on a polymer. It is a coating that is used in a seawater environment at 20 C. If dG/dt and Ea are equal to 50 Pa/s and 10 kJ/mol respectively, what is Ao of the system.

What are 2 of the 4 principles of bioethics? Give either one example situation breaking one of the principles you listed and be clear which one it is breaking. 

Autonomy- A doctor gives a surgery that could get rid of the problem permanently as an option withholding information about a long term medication that could have the same effect. The patient is consenting to the surgery not being informed there are other options. 

Non-maleficence

A. What is the composition (percentages) of the water, protein, and fat in the skin?

B. If a person weighed 100 lbs, on average, how much would your skin weigh?

The skin is composed of 70% water, 25% proteins, and 3% fats. (The other 2% accounts

for all other chemicals found in the skin). If someone weighed 100 lbs, the skin would weigh 15 lbs.

Skin weight = 0. 15 * body weight [lbs]

What are two things that directly affect the conductivity in different metals? Be sure to explain what each is and how they affect the conductivity. 

1. The number of valence electrons affects the conductivity differently. Usually as the number of valence electrons increases, the conductivity increases. More valence electrons allows for more to be conducted, making the metal have a higher conductivity.

2. Metals that have a higher crystal structure tend to have a higher conductivity. This is due to the fact that the electrons are able to move more freely around the crystal structure. 

3. As temperature increases within a metal, the conductivity decreases. This is due the positive metal ions vibrate from the rise in temperature. This interferes with the electrons ability to move freely around the metal crystal lattice.

4. Metals with lower conduction bands tend to have higher conductivity because it is easier to excite the valence electrons out of the valence band. 

Explain the importance of choosing a precursor material for carbon fiber production and how one of the two most common precursors is a good precursor?

The precursor material for carbon fiber production is the starting material for further processing. This choice can significantly determine what properties carbon fiber has. Furthermore, around 50% of the precursor’s initial mass may be lost due to gaseous by-products in later steps. The loss of material is both product- and cost-ineffective.

PAN is a good precursor because it is a long-chain, organic molecule that is optimal for ring formation. Mesophase pitch is a good precursor because it is a large, organic molecule with a lot of aromatic rings, which is good for producing carbon fibers.

Explain the differences between wrought and cast aluminum. What advantages does wrought aluminum have over cast aluminum, and where is it usually used?

Wrought aluminum is heated and then formed & shaped through physical deformation through processes such as rolling, extruding, and forging. Cast aluminum is aluminum that has been heated up and poured into dies or molds to form the desired shape. Wrought aluminum tends to be stronger and doesn’t exhibit as many internal and external defects as cast aluminum does, which allows it to be used in structural aspects in comparison to cast aluminum, which is much weaker and cannot exhibit as much strength. 

The fracture toughness of a metal is being determined experimentally. Upon heating the metal, it is discovered that the fracture toughness of the metal increases. What property of the metal changes to allow for the fracture toughness of the metal to increase? Does it increase or decrease? Additionally, name a potential crystal lattice structure for the metal.

The property of the metal is ductility, which increases to result in an increase in fracture toughness. This property is observed in metals that possess a BCC crystal lattice structure.

How does the absence of a grain boundary affect the properties of a crystal? 

It will have a higher strength because there are no sites for dislocations to happen. It will have uniform electrical properties. It will have unique optical properties due to anisotropy.

Explain the differences between Transtibial Prosthesis and Transradial Prosthesis.

Transtibial- artificial limbs that start below the knee & are the most common

Transradial- artificial limbs that start below the elbow & are less common, but more complicated

As the lead chemical engineer at a chemical plant, you are tasked to build a reactor out of a limited choice of metals: gold, zinc, and stainless steel. What metal is best for this design taking into consideration resistance to corrosion and cost efficiency. How could you make least effective metal of these choices more resistant to corrosion?

Stainless steel is the best option as it does display corrosion resistance but is also cheaper than gold.

Zinc is the metal most susceptible to corrosion. Its resistance to corrosion could be improved by plating it with a more corrosion resistant metal or applying a protective coating like paint to it.

Out of the four bone cells listed below, pick two (5 points each) and explain their function in the remodeling process. Additionally, include where they may be located during this process. You may include a picture if necessary for your explanation.

• Osteoblasts

• Osteocytes

• Osteoclasts

• Bone lining cells

Osteoblasts: Osteoblasts are the builders of the remodeling process. They use minerals (calcium} and/or stem cells to make/repair bone tissue in the growing matrix. These are found on the surface of the bone before the bone lining cells are formed.

• Osteocytes: Osteocytes are the "roots" of the remodeling process. They transfer waste and nutrients throughout the bone through the use of channels. They are found trapped within the matrix of the bone.

• Osteoclasts: Osteoclasts are the eaters of the remodeling process. They absorb the old bone and release the minerals stored from absorption. They also create new space for bone to grow. They are found on the surface of the bone, much like osteoblasts and bone lining cells.

• Bone Lining cells: Bone lining cells are cells that line the surface of the bone, forming an ionic barrier in the process.

Give me an explanation of the three primary optical properties. 

Reflection of Light – When a ray of light approaches a smooth polished surface and the light ray bounces, it is called the reflection of light. 

Transmission – A process in which incoming photons pass through a material without interacting.  

Refraction of Light – Refraction of light is the bending of light rays as they pass from one medium to another, meaning changing the path of the light rays.