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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Material for moisture moderation

Do you know of any material that can moderate the level of moisture of its local environment? Example: if the desired moisture level is 30% and the local environment of the material is at 6% the ...
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8 views

Material that can provide soft flexibility, while maintaining conduction “accuracy”

I hope material search may be valid here. Is there a material that can be shaped as a few millimeters thick sheet, that can be placed on top a touch surface (e.g. iOS/Android tablet, Wacom drawing ...
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2answers
45 views

Why is steel-reinforced concrete stronger than ordinary concrete?

Is it only because steel has higher elasticity? What other factors are involved?
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18 views

What is the yield strength of a bar of different cross sections?

Will the yield strength of the combination will be same as that of the rod of uniform cross section?
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11 views

What are some structures which minimize surface stress upon expansion

Intro I am currently researching into a problem involving the cyclical expansion and contraction of a 3 layered structure comprised of an internal metal encased by another metal encased in an outer ...
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38 views

Does induced current affect the permeability of a material?

For electromagnetic wave propagation, we can typically characterize a medium by conductivity $\sigma$, permeability $\mu$, and permittivity $\epsilon$. Consider if this material had current passing ...
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166 views

How many molecules rub off when I press a key?

I have a lot of questions below but my overarching questions are: Do surfaces rubbing lightly together always strip molecules off of each other? and How can we model that? Clearly the answer to the ...
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2answers
7k views

How does a knife cut things at the atomic level?

As the title says. It is common sense that sharp things cut, but how do they work at the atomical level?
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1answer
43 views

Demagnetisation by throwing a magnet

I tried to answer this question in a book about electrodynamics: How to demagnetise a permanent magnet, ie. described by $ D_T$ change into described by (0,0) I figured out about heating it up ...
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194 views

If atoms have specific energy levels, why do opaque solids absorb all visible light, not just some? [duplicate]

Here's my question: if atoms have well defined energy levels and those differences correspond to the frequencies of light that can be absorbed, how is it that opaque objects absorb all or most visible ...
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8 views

Pearlite or spheroidite?

If steel alloy having either pearlitic or bainitic microstructures is heated to, and left at, a temperature below the eutectoid for a sufficiently long period of time (e.g.24hr), spheroidite will ...
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32 views

How hard is ice? [closed]

I know that there are many different types of ice and many ways for ice to form but I want to know about ice that a human might typically encounter, i.e. from a freezer or a sub-zero environment ...
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125 views

Question about supercooling

During the cooling of a liquid, if no impurity of site of nuclearation, an appreciable solidification will begin only after the temperature has been lowered to below the equilibrium solidification (or ...
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37 views

How can a paper battery behave like a capacitor?

I was trying to understand how paper batteries work and came across some explanations saying that the paper battery can also behave like a supercapacitor on account of its ability to discharge and to ...
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14 views

Color of cementite

I have a question about micrograph of steel. In eutectoid steel, the pearlite exists as grains, within each colony the layers are oriented in essentially the same direction, which varies from one ...
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74 views

A physicists perspective on a material science/engineering problem

I am looking into some research that involves engineering and material science. As a physicists I wondered what other physicists would think of this problem and how they would approach it. Much of the ...
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1answer
19 views

intermetallics and solid solution

For some systems, discrete intermediate compounds rather than solid solutions may be found on the phase diagram, and these compounds have distinct chemical formulas; for metal–metal systems, they are ...
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44 views

Graphene conductor? [closed]

I was thinking if we had a a busbar that can carry massive amounts of current(since its resistance is $0.9\, \mathrm{\mu \Omega}$), and it's weight is $15\, \mathrm{kg}$, I assume if graphene would be ...
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40 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. ...
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3answers
203 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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27 views

A question about residual stress

Shot peening is a process of inducing residual compressive stress on the surface layer of metal parts. When shooting particles are colliding on the surface of metal there is a compressive stress. My ...
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4answers
114 views

Surface area of glass (or general material) and strength

How does the surface area of a piece of glass (or any general material; sapphire isn't technically glass) correlate with strength? Strength as in resistance to pressure concentrated at a small point? ...
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80 views

Where I can find information about how helium gas diffuses through different polymer materials

I need more experimental information about helium gas diffusion in solid materials such as different plastics, metals, ceramics etc. For example I am scientifically curious about what is the polymer ...
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1answer
36 views

What is the meaning of $\%E$ on a graph?

I'm reading the book The New Science of Strong Materials by J.E. Gordon. He writes when we plotted (...) breaking strain, against thickness, we found it did not matter what the whiskers were made ...
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1answer
37 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 ...
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1answer
46 views

Where will a board break when weight is added to the end?

If you have a board, say a standard 2x4 of finite length, where one end is fixed in a cement wall and the other end is free, and you begin adding weight to the free end until it breaks, where will the ...
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8 views

Determining porosity in metals

I am in need of a book (preferably) or other reference material which would help technicians determine whether porosity exists in the fracture face of a tensile test bar for a variety of different ...
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1answer
45 views

Is there a textile like material that can act as a spring? [closed]

Imagine some sort of textile (as in very light, not metallic) that is tightly rolled up, can be easily unrolled by applying some force (i.e pulling it) but when released will eventually return to it's ...
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3answers
45 views

Does Mohs scale of mineral hardness always hold?

According to Wikipedia's article on the Mohs scale of mineral hardness, materials / minerals with a higher rating cannot be "visibly" scratched by materials with a lower rating. It goes on to admit ...
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88 views

Not-so-hot black shirt

As it is getting warmer here by the minute I was asking myself: Are there materials, that are black (in th visible range) but reflect (most) invisible light? Furthermore, I asked myself what ...
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82 views

Is Sapphire crystal flexible?

It is widely rumoured that the next iPhone's screen cover will be a sheet of synthetic Sapphire crystal. A video purporting to show a leaked part has emerged. The chap in the video (Marques Brownlee) ...
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1answer
139 views

Why is powdered sugar less dense than granulated sugar?

The density of powdered sugar is about 20% lower than that of granulated sugar. There is small composition difference between the two - about 3% cornstarch and 0.5% water in powdered sugar, but that's ...
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1answer
66 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. ...
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65 views

How does a fabric containing 10% stretch material make it stretchy?

Why should adding a small amount of a stretchy material make an otherwise non-stretchy fabric stretch? Shouldn't the non-stretch fibres still constrain the maximum stretch of the fabric?
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3answers
102 views

Which is stronger, wire rope or chain?

Assume they are the same material with the same weight, which is stronger?
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1answer
63 views

What keeps objects made of gold apart? [duplicate]

I was told the following basic facts: Objects made of the same metal don’t fuse in the atmosphere because they form an oxide layer. They do fuse in space. Gold doesn’t oxidize. Yet, gold nuggets ...
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41 views

What keeps objects made of the same plastic apart?

I have two objects here which are made of the same plastic. When I hold them together, they remain separate objects: I can pull them apart with no resistance. How does each atom/molecule “know” which ...
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1answer
48 views

Does the Night Mode of the screen display (LCD) save more energy?

In some cases, we can enable the Night Mode (reversing the bright and dark color of the display; such as White Text, Black Background) for the screen display. LCD(Liquid-crystal display) seems to be ...
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1answer
28 views

Glass Hardness and Pressure

How is glass hardness defined? I understand that ordinary kitchen knives cannot scratch most toughened glass, such as the ones found on cell phones. However (I once tried) - with enough pressure, one ...
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1answer
22 views

Why defects moderate (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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77 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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2answers
131 views

Can Aluminium be softened

I have an aluminium baking plate that I did put in a very hot oven and now it is soft, so I can bend it or almost roll it up. Why?
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1answer
62 views

Reducing Friction between 2 abs plastic bodies [closed]

Here at the company we've been working on a new product, and it will more than a few times a day and with a considerable force, slide on a plastic surface, being itself, another plastic body, roughly ...
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1answer
29 views

Why do pores make ceramic opaque?

I want to know how a ceramic transparency is mostly affected by the pores, grain boundary, second phases etc. present inside of it, but the major contribution is due to the pores. Let's consider the ...
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112 views

Are there materials that get softer with temperature decrease?

Could be there material that begins melting/softening when it's temperature is lowered? I would say no, but I've seen enough physics to know that not always life is so easy. Moreover I think I've ...
2
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1answer
53 views

How does tempered glass work?

I've read that tempered glass work by heating and then rapidly cooling the glass so that the outer layer 'freezes' (stops expanding/contracting) but the core contracts further as it cools. I'm told ...
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3answers
153 views

What makes materials hard and strong?

This is something I have wondered for a long time. Why are some materials like steel, diamond, and even light materials like graphene stronger than others? Is it due to the strength of the ...
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45 views

Is there quantitative theory of cutting with edge or blade

I wonder if there is some simple theory of what determine efficiency ( speed, energy end force required ) of cutting by edge ( blade , knife, sword ) At least something phenomenological like in ...
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1answer
164 views

Why does finely cut paper curl?

When paper is cut to a small width, it curls up like this. Why does this happen?
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2answers
63 views

What makes a material a good lens for CO2 lasers?

I read on Wikipedia that zinc selenide and germanium make good lenses for $\mathrm{CO}_2$ lasers. My question is, Why?