# Tag Info

## New answers tagged material-science

1

ZnO and GaN are both Wurtzite structure, with a very similar lattice constant; by contrast, Si is diamond cubic. Also, the thermal expansion coefficients of ZnO and GaN are very similar. The following is taken from this article by Hanada Lattice constants: and coefficients of thermal expansion: The corresponding numbers for Si are thermal expansion ...

1

I can't speak specifically for organic polymers, but I will try my best for polymers in general. Every bulk polymer is made of thousands polymer chains, which is made of many "mers" (Greek for unit). Consequently we have the name polymer . For many polymers at room temperature these chains are able to rotate, and because the bonds are not 180 degrees apart ...

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By symmetry you know that the stress at each plane of symmetry must be perpendicular to the plane. Take two planes of symmetry at 30 degrees from each other to section off 1/12th of the hexagon. Now you just have a beam with a constant pressure and two point loads at the corners. Since the net force must be zero, the component of the force applied at the ...

2

The Young's modulus of steel doesn't change significantly between say 10ºC and 20ºC (I'm guessing this is roughly the range of temperature between morning and midday). So the stiffness of the steel won't be changing. However I would guess that the steel wire has a polymer binding it together, and possibly a polymer coating on the outside of the wire as ...

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Though we may be a while away from the ability to make the all important material, we could in fact start working towards this now. A while ago I penned a small idea for building 2 elevators, the first of which would be a "Lunar Elevator". With greatly reduced gravity, the tensile strength of the cable would be reduced to well within the art of the ...

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As stated by Steeven, strain is not a property of a material. Instead, strain is something you do to an object … just like rotation is not a property of an object, but is an action you do to an object. In fact in 3d space (ie: x,y,z), rotations and strains form the group GL(3,R). This is the group of all invertible 3x3 matrices M of real numbers. We can ...

3

As far as I know, there is zero physics in "Crystal Energy", which if I understand what you mean, is related to Crystal Healing. There is a good bit of validity to the placebo effect and belief, so a person believing in something, whether the practitioner or the patient, can have an effect or the impression of an effect, but that's not physics either. ...

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Crystals have internal energy including some energy associated with molecular vibrations. Amorphous materials have internal energy including some energy associated with molecular vibrations. In addition to molecular vibrations, crystals can exhibit mechanical (macroscopic) vibrations. An example of a resonant macroscopic vibrator is a tuning fork. But, ...

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See, a crystal due to its temperature and through various media can be made to vibrate. Now because of the fact that the atoms(lattice points, could be molecules too) are connected with each other, the vibration actually spreads in all directions. Thus this vibration acts as an wave. But the whole of crystal, because of its structure can vibrate only in ...

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I suspect that this question is resolved in the same way as for metal? Perhaps you've seen the famous (visionary) lecture by Feynman on nanoscience (before it existed), he argued for what is now known as cold welding, using an argument that I think applies to paper too. I reproduce a relevant quote from Feynman's celebrated "Feynman lectures on physics" ...

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Paper is a mesh of fibres usually mixed with a binder and some clay. The fibres will in turn have some microstructure depending on their origin (cloth, wood, etc). Ultimately the paper is composed mostly of cellulose molecules. When you tear paper you are mostly pulling the mesh of fibres apart. If you look at the torn edge closely you'll be able to see the ...

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@FasEtNefas presents us with this quote: Now suppose a uniform binary mixture [e.g. a CuCr metal alloy] at a high temperature and concentration u∗ is suddenly quenced to a given lower temperature. A commonly occuring situation is that there is a pair of values of u [which is the local concentration of one of the components], say u1 and u2, and a ...

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Various single crystals can be cleaved to an atomically flat surface. There's a high temperature superconductor that is strongly planar, but with weak interplanar bonds that can be made atomically flat by simply sticking a sticky tape on the surface and ripping it away

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So for anyone looking for the answer in future. I will use this values: k=0.3 W/m/K (thin film value from Ta2O5) Cp=600J/kg/K (taken from NIST thanks Floris) roh=4500kg/m^3 TEC=5*10^-6 (thermal expansion coefficient of Ta2O5)

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Another possible source of data: Thin films and nanostructures of niobium pentoxide: fundamental properties, synthesis methods and applications Abstract: As one of the transition metal oxides, niobium pentoxide (Nb2O5) offers a broad variety of properties that make it a potentially useful and highly applicable material in many different areas. In ...

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Heat capacity of $Nb_2O_5$ from NIST's database, for a wide range of temperatures using Shomate equations. But thermal conductivity and thermal expansion coefficient will be very hard to find.

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Have a look at the following idealised binary phase diagram: The vertical axis is temperature, the horizontal is composition (in mole fraction but weight % would work too here). Say we started from point 1. where the alloy is fully liquid with a well defined composition, say $u$. Now we cool down, following the red line. At some point we hit the black ...

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You can't reasonably solder to aluminum, since it almost instantly forms an aluminum oxide layer, and alumina is as close to inert as makes no never mind. The flux that removes oxides from materials like copper simply aren't active enough for aluminum. There is nothing to keep you from depositing a different metal, though. Gold, silver, copper or nickel ...

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Those are nickel/steel brackets that have high magnetic permeability and saturation. Due to the magnets shallow thickness the magnetic fields are completely diverted into the bracket preventing any mag fields from penetrating through it. Notice how the magnet is strongly attracted to the bracket due to magnetic attraction, if you unglue the magnet from the ...

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The image shows the stress-strain curve for a structural steel (not to scale). The steel has a ductility, i.e it has a failure strain, of just over $\epsilon_y$, after which it breaks. Start loading from the origin and you initially go up the straight line of slope $E$. Up to the initial yield stress of $^0\sigma_y$, the material is elastic and, if ...

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The thickness of your rubber sheet definitely affects the force you will need to apply for a given amount of elongation. Thickness also affects the breaking point, and therefore the tensile strength, of your rubber sheet. Young's modulus describes the elastic property of a material up to the limit of its elasticity. It's a measure of the force per cross ...

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This colour change effect occurs when the strands of plastic material, the polymers in the plastic, start to stretch as you twist the plastic. As they do so, this changes the way the light is reflected from the plastic. Say for example, you chew a biro top, by doing so, the Refractive Index of the plastic is altered, from its original colour, to a whitish ...

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The water analogy is good but think of the water as force and not stress. Equilibrium applies to forces, not stresses and, essentially, what flows in at one end emerges at the other end. In Mechanics 1, you'd simply divide the force in each constant-area element by its area to get the average stress in the element. However, as @Tyler's FEA shows, this ...

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In addition to WhatRoughBeast's excellent answer let me also debunk the 'Thermite myth' that's so pervasive in 9/11 conspiratorial thinking. This misconception that burning Thermite could cause steel beams to melt is based on a poor comprehension of Heat Transfer. Adherents of the Thermite thesis start from the correct knowledge that burning Thermite ...

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Given adequate oxygen, certainly. From here, for instance, you can get an approximate maximum flame temperature for kerosene burning in air, and a higher concentration of oxygen will increase the temperature. At 3800 F, this is about 1000 F above the melting point of steel, so melting steel with jet fuel (kerosene) is entirely possible. Of course, "Common ...

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