The study of how the properties of matter arise from its structure at all scales and of how processing can be used to modify those properties (often in pursuit of a specific application).

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What material are screen protector films made of? [on hold]

To protect touch screens from scratches various plastic screen protector films are available for application on top of the actual screen. There are cheap vinyl ones and there are expensive tempered ...
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1answer
80 views

Grain boundary sliding in creep

To prevent grain boundary sliding so that creep is less likely to occur, usually engineers would design components of larger grains or have columnar grain structure to prevent grain-boundary sliding. ...
11
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2answers
483 views

Are synthetically-produced diamonds as hard as natural diamonds?

I was having a discussion with my friend about the intrinsic worthlessness of diamonds (DeBeers and whatnot) and how synthetic diamonds haven't caught on, again because of the marketing/propoganda ...
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0answers
22 views

Activation energy as a function of defects

Electrical conductivity has a form of Arrhenius equation. It is assumed that activation energy decreases with defect density in the insulating state and becomes zero in the conducting state. Can one ...
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2answers
299 views

Why magnetic monopole found in spin ice don't modify the Maxwell's Equations?

Magnetic monopole predicted by Dirac nearly a century ago was found in spin ice as quasi-particle(2). My question is Why magnetic monopole found in spin ice don't modify the Maxwell's Equations? (I ...
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1answer
53 views

Energy conservation of permanent magnets engine

How to explain the fact that magnet can attract an object (apply a work W) without losing a (significant) part of its internal energy? How to apply the energy conservation principle? Please think to ...
4
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1answer
67 views

How can one reasonably theoretically model polycrystalline materials?

Many techniques are taught in advanced solid state courses but they are almost all derived for perfectly crystalline materials. For example, band structure really only appears theoretically when you ...
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1answer
42 views

Working out the penetration of radioactive decay products

From my understanding of the products of radioactive decay (alpha particles, beta particles, and gamma are all I know of), the particles (or energy I guess?) are stopped by a medium according to it's ...
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1answer
52 views

Work functions of ceramics/insulators

Is anyone aware of or know of a good source or means of estimating the work function of a ceramic material? Typically, work functions are given for pure elemental metals, rather than for compounds, ...
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0answers
28 views

What exactly is cutting with a knife will look like on the atomic scale? [duplicate]

Some times I like to view the world in the microscopic scale .ie. at this level all objects any thing will be collection of atoms which we normally don't view with our naked eye. At that scale I ...
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3answers
6k views

Why don't FCC metals have a brittle-to-ductile temperature transition?

I initially thought that it had something to do with the number of slip systems in FCC vs. BCC, but they're both the same.
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1answer
122 views

Degree of anisotropy of crystal tensors

Does there exist a scalar that can describe how anisotropic the elasticity of a crystal is? What about other tensors such as the permittivity or susceptibility? I found a Wikipedia article that was ...
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1answer
116 views

Is it possible that a battery goes flat faster in a cold environment?

I own an old iPod Classic with original lithium-ion polymer battery and I use it primarily while running. Recently I discovered that when a temperature outside is low, usually below 5 C degrees, the ...
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0answers
8 views

Is there any relation between single crystal elastic constants and plastic deformation?

The elastic constants are the tensor coefficient in Hook's Law. Which are valued only in elastic region.But, we are using elastic constants to find the hardness.The hardness is the measure of the ...
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0answers
10 views

absorption and reflection of sound on molecular level

Can someone explain the reflection and absorption of sound on the molecular level? What really is reflection? Why porous and soft material absorbs sound? What's the definition of soft in terms of ...
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1answer
144 views

What factors cause the velocity saturation to occur at different electric fields for different materials?

In semiconductors the velocity of carriers gets saturated after a certain value of electric field. In silicon it occurs at around $10^4 kV/cm$ and in GaAs at some other value. What factors are ...
3
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1answer
2k views

Penetration of armor plate

Is there a simple mathematical expression for the stopping power of a given thickness of armor, given the thickness of armor plate, the radius of a cannon ball, the density of the cannonball and the ...
3
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1answer
377 views

Semiconductor problem: how much Boron is required to establish a certain amount of charge carrier density

The problem description is as follows: Boron is used to dope 1 kg of germanium (Ge). How much boron (B) is required to establish a charge carrier density of 3.091 x 10^17 / cm^3. One mole of ...
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1answer
90 views

Malleability in metals

I am trying to understand malleability in metal as a result of the micro structure. I am focusing on the metals of antiquity (in order of decreased malleability): Gold, Silver, Copper, and Iron. While ...
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1answer
25 views

What properties make a good catalyst?

Specifically, I am thinking about metal catalysts that do not (apparently) take part in a direct chemical reaction. Is there any general method of either finding a catalyst for a given chemical ...
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2answers
281 views

Why does foam dull knives?

I have recently taken up prop making and just started my first foam-built costume from a video game. These kinds of costume armour builds are often built out of the various foam floor mats you can buy ...
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1answer
43 views

Work out friction coefficient using the two material's properties

For a physics engine I am working on, I need to know two object's friction coefficient (for bouncing, collision detection, friction in general etc.). Since this physics engine will have lots of ...
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1answer
5k views

How to know what materials are good conductors of electricity?

I'm not asking a question like "Is the wood conductive?". No. I'm asking what properties do they have to have to be good conductors. Theoretically I mean. Thanks.
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1answer
55 views

Why the tyres of vehicles are always found to be black? [closed]

Generally, it happens. I never seen vehicles with tyres of different color other than black..?
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4answers
612 views

Does extreme cold make **everything** extremely brittle?

First of all, I'm genuinely sorry if this question isn't "serious" enough for this forum! A common cliche in movies and tv is that a very tough object (eg the villain) is frozen, and then hit with ...
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1answer
765 views

Stress due to the mismatch of thermal expansion coefficients of two different attached materials

I'm simulating the thermo-electro-mechanical behavior of a copper wire which is surrounded by silicon dioxide. In other words, the wire segments is under mechanical and thermal loads and at the same ...
5
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1answer
162 views

Force problem related to adhesive and bonding

I have two PCBs (printed circuit board), and they are glued by adhesives, as show in the pictures. And the location of the adhesives are indicated on the picture (please notice that NO adhesive is ...
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0answers
38 views

Structure of Metallic Hydrogen [migrated]

I am simply curious what the theoretical arrangement of metallic hydrogen would be. I found this article which gives a picture, but I don't understand what the labels mean (e.g. is H5 an isotope, ...
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1answer
34 views

Perovskite's material parameters?

Perovskite's material parameters? What are the major material parameters being investigated? [For example, water solubility, absorption characteristics, surface energy etc]
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2answers
81 views

How absorption coefficient determines which material is used to make solar cells?

Does the knowledge of the material absorption coefficients aids engineers in determining which material to use in their solar cell designs? If yes, how?
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0answers
37 views

Why do clothes look darker or change color when they get wet? [duplicate]

Clothes can look darker or change color when they get wet. Why does this happen?
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1answer
34 views

Why defects reduce electric field?

I am running a simulation with drift-diffusion equation, Poisson equation and Fourier heat equation with a metal/insulator/metal structure. In my simulation, initially electric field is at the top of ...
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5answers
6k views

Why wet is dark?

When something gets wet, it usually appears darker. This can be observed with soil, sand, cloth, paper, concrete, bricks ... What is the reason for this? How does water soaking into the material ...
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2answers
49 views

Software for analysing SEM or TEM images

I am looking for a software to analyse SEM and TEM images of some PLD experiments because I want to characterize the samples, like calculate the concentration of nanoparticles, size, and do some ...
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1answer
300 views

If my lattice has an atomic basis, do I also find the reciprocals of the basis vectors to get the reciprocal crystal structure?

That is what my crystal structure looks like. The blue atoms sit on every lattice point (basis vector of $\{0,0\}$) and the red atoms have basis vector of $\left\{{2\over3},{1\over3}\right\}$. The ...
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1answer
36 views

Physical Constraints of Very Large Humanoids [closed]

I loved Godzilla movies when I was a kid (still do), but ever since Pacific Rim came out, I have been pondering just how implausible really large humanoids would be given the laws of physics. For the ...
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1answer
44 views

Linearity of thermal expansion of metals?

I am having to do a path length correction for a metal tube (stainless steel 316, 16ppm/C) from 0-100 degC. I need to correct to within approximately 1 ppm. How much do typical engineering metals ...
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1answer
54 views

Why do we have Indirect bandgap semiconductor?

If the energy of an electron is proportional to square of the momentum k, how come we have a Indirect Bandgap material in which the minimum of the energy in conduction band is not at k not zero. P.S. ...
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1answer
35 views

Mullins effect in the elastic material

I was thinking on a experimental question, but I couldn't get the answer: How can we measure how the Mullins effect influences in the pressure inside a balloon? (I mean that, if there is a formula, ...
3
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3answers
126 views

How to block neutrons

What is a good way to block neutrons and what is the mechanism that allows this? It's my understanding that polyethylene is somewhat effective. Why?
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1answer
39 views

Does the magnetic anisotropy state only have two possible directions?

Wikipedia says "The magnetic moment of magnetically anisotropic materials will tend to align with an easy axis". Does this mean that it is completely impossible to orient the magnetic moment with any ...
2
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1answer
64 views

How much weight would I need to put on the end of a tube to break it?

Say I have a tube with a circular cross-section made from some material (for an example, I'd like to use acrylic). I support it horizontally from one end and hang a weight from the other end. How ...
5
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0answers
87 views

What would happen to a submarine coated in water repellent

I saw the article about laser-etched hydrophobic metal, and it got me thinking, how would a submarine function differently if coated as such? Would it move faster, sink completely, be unable to move ...
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1answer
35 views

Applications of partial differential equations in material science [closed]

I've been asked to find a partial differential equation that has applications in material science. However we are not allowed to use the heat equation. I have found Fick's laws (basically the heat ...
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0answers
14 views

Steel and aluminum fatigue limit

Is it true that steel has a fatigue limit? Is it true that past a certain number of stress strain cycles, steel will last indefinitely if its ultimate strength after the specified number of stress ...
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1answer
36 views

Plasma frequency

I have a neutral plasma and I need to solve Maxwell equations given the charge and current densities on the plasma. In order to do it I need to know the electrical permittivity $\varepsilon$, I've ...
2
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3answers
124 views

Materials with directional friction property?

At the macroscopic level a simple metal file or rasp creates a large amount of friction in one direction and a much smaller amount in the opposit direction. Shark skin displays the same properties due ...
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1answer
65 views

Relationship between electrical resistivity and density

I just read this answer on EE.SE and that triggered a doubt in me. If I were asked whether there is any relationship between the electrical resistivity and the density of a substance I'd answer ...
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0answers
29 views

Finding the strains from a 0, 90 rosette - Mohr's circle

I have used a strain rosette with two gauges at 0 and 90 degrees to find strain on a beam under force and an trying to plot Mohr's circle for the problem. As the gauges are at right angles finding the ...
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3answers
307 views

Melting and Boiling Points of Odd Materials

In Chemistry, I was taught that there are three main states of matter: solid, liquid, and gas, and that heat and pressure determine that state. For some substances, the line is blurry between them. ...