Tag: Material science

Transistors

Transistors

02/03/17

“How can we apply our knowledge of semiconductors to create electronic switches?”

P and N type semiconductors are highly useful devices for creating a controlled electric current. However, how could we apply this technology to create something incredibly useful? Well, let’s use our technical mindset to figure this out. We know that if an N type and a P type were hooked up together and the P type had a higher voltage than the N type,, then a flow of extra electrons from the N type (called the “emitter” would come in to fill the P type (called the “base”). Furthermore, if there was an another N-type (called the “receiver”) electron on the other side of the P-type that was even more positively charged, then we would be able to not only have an electron flow but be able to control the amount of current flowing. However, our only problem is that this operation can only take place if both the base and the receiver had a positive voltage. This can be easily fixed through applying a positive voltage to the base, allowing not only for a current to take place but control of the current and voltage to happen as well, effectively making a switch with no moving parts! This is the foundation of an electronic component known as the transistor, and is what allowed for the modern computer revolution to have taken place!

P and N-type semiconductors

N-type semiconductors

02/02/17

“What are the fundamentals of the fundamentals of solar cells?”
Solar cells are one of the most magnificent devices that humanity has conjured. However, what exactly makes them tick? To find out, let’s go take a look. If one were to analyze a solar cell with a magnifying glass so powerful that it could see in the microscopic level then we would find a multitude of small, three terminal devices. These devices are known as Transistors and have very special properties. Specifically, it can work as a switch without moving parts! However, before we understand transistors, we must understand what cause them to work. Half of the composition of transistors are composed of objects known as P-type and N-type semiconductors. P-type semiconductors hold an impurity of boron[B], which holds one less electron than silicon, while N-type semiconductors are have a small impurity of phosphorous [P], which holds an extra electron than silicon. When combined, these semiconductors will have more mobile charges and can conduct current better.

Hydrogen fuel cells

Hydrogen fuel cells

01/20/17

“Is it possible to extract the energy from fuels without an internal combustion engine?”

Fuels are tremendously useful substances for portable energy storage. However, extracting said energy from them is typically a highly pollutive process. But instead of disposing of this technology altogether, could it be possible that we could use our engineering mindsets to create a pollutive free fuel extractive technology? Well, let’s think about it. We know that fuels are typically rich in hydrogen [H2] gas, and we know that the surrounding atmosphere (at least on earth) is filled with a copious amount of oxygen [O2] gas. Furthermore, hydrogen in its ionized state has a positive charge and oxygen has a negative one, and that a current can be created if positive and negative charged states were connected together in a circuit. So what if we were to create a contraption that would separate the hydrogen gas into hydrogen ions and the oxygen gas into oxygen ions, funnel the extra electrons from the hydrogen side into the negative oxygen side, and finally combine then dispose of the surplus hydrogen and oxygen by combining them into water and flushing them out? This is the exact operating principle behind hydrogen fuel cell technology. Hydrogen fuel cells are typically implemented in automobiles and their demand growing at an exponential rate, with a 65% increases in sales from 2014-2015!

However, one must be cautious when using this technology. Because all fuels will be composed of more than hydrogen gas, those chemicals will be released as well, inducing pollution. In addition, these impurities can cause short circuiting. Since we all aspire to be scientific thinkers, we must be remember to be cautious of any new breakthroughs.

Energy density and it’s importance

Energy density and it’s importance

12/02/16

“How do scientists and engineers measure the density of energy within a system and why is it important?”

Energy is a quantity that is used omnipresently for calculations in all branches of science and engineering. However, energy is more than a theoretical abstraction, and since it is tied to the material universe, it must be stored somewhere in reality, such as in objects. And since objects of the same size can have different abilities to hold energy , we will need some conceptual way to understand this. As a result, scientists and engineers have developed the concept of energy density to represent the amount of energy stored within in object. Energy density is an important concept because when analyzing energy storage mechanisms such as batteries and capacitors, once must take in to consideration the volume vs power limitations that a project might have. To illustrate, let’s say that you want to build an autonomous boat. Since this boat will have no people on board, it will need a mechanism to power it’s systems. However, the boat can not uphold too much weight, or else it will sync. Therefore, when designing such a contraption, engineers will have to choose an energy storage technology with a high energy density.

Alloys

Alloys

11/02/16

“What is special about a mixture of two elements?”

Materials are composed of elements. Some are composed of many. However, what are some special properties of mixtures that involve metal? Well, after much research into the subject, Chemists have defined these materials as alloys. Since different elements have different size, and alloys are made up of different elements, the internal structure of alloys will become fairly irregular, therefore giving alloys a much harder nature. As a result, alloys are regularly applied in industrial applications where durable materials are necessary.

Material fatigue

Material fatigue

10/24/16

“What happens when a material is subjected to multiple loads in a period of time?”

We all know that materials respond to loads through deformation. But what happens when a material is subjected to a heavy amount of cyclical loads? Well, let’s think about it like engineers. We know that when a material experiences a large amount of stress, microscopic cracks begin to appear in it’s structure. And we also know that if the structure continues to withstand more damage, then these cracks will be exacerbated until a rupture occurs. This effect (termed by engineers as material fatigue) can cause a structure to collapse even if the applied stress is far below the yield point.

Normal stress

Normal stress

10/08/16

“What happens when stress acts upon an area parallel to the axis of an object?”
The concept of stress is one of the premier foundations of all of engineering science. So, what happens when a stress is applied to an area that is parallel to the axis of the object? Well, this type of action is very simple. Since all of the stress acts through the axis of an object, the only deformations will be parallel to the axis as well. This type of stress would cause tensile or compressive deformations (depending on the direction and strength of materials). Scientists and Engineers have termed this phenomena normal stress. You can find the magnitude of normal stress very simply, as the stress is just the force distributed over the area that it is acting upon (we can represent this symbolically with the equation (sigma)=F/A, with being (sigma) the stress, F being the force, and A being the geometric area)

Polymers

Polymers

08/31/16

“Are there chemical chains that can repeat themselves, and how do they relate to spider silk?”

We all know that different molecules can form bonds with one another. However, could we have a complex bonding structure that is made up of smaller, repeating, individual bits? This is the fundamental idea behind polymers. Polymers are large molecules made up of repeating units called monomers. The properties of polymers are contingent upon how their connecting-framework is built and the material that makes up the framework. For example, some polymers can be very sturdy, while others can be quite placid in nature. Polymers can be made naturally or synthetically. For example plastics are a polymer-based material, while phenomena as fundamental as DNA is also a polymer, and even spider silk is a polymer! In fact, the polymer build of spider silk is so powerful that a single pencil-width strand of the material could stop an entire Boeing 747!

Shear strength

Shear strength

08/30/16

“How can we classify the ability of a material to resist forces that are parallel to the surface?”

Have you ever been mystified by how an object can be broken apart by taking two different sides and sliding one upwards and the other downwards? And have you ever thought about how we could quantify this phenomena? Well, believe it or not, this comes down to a very simple factor called shear strength. Shear strength is the maximum ability of an object to resist yielding against shear strains, or deformations in objects that are induced by internal sliding. Adhesives are often used to solidify the shear strength. The study of shear strength is critically important for structural engineering, as doing so could prevent catastrophic failures. For example, we can apply the shear strength of materials to study how a boat being tethered to a dock could cause a rupture on the dock.