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28

A crystalline substance doesn't necessarily have to be a single crystal to be deemed as such. An amorphous solid such as glass doesn't exhibit a crystalline structure even at very high levels of magnification. Glassy substances have a glass transition phase that is lower than the melting temperature. The melting point of ice formed under ordinary ...


13

Ice, as in the ice you see in cold weather, is most certainly a crystal. In fact ice has at least 11 different crystal forms depending on the temperature and pressure. The form we see on a cold day is ice 1h. A glass, i.e. an amorphous solid, is a material that has no long range order and shows a glass transition rather than a distinct melting point. It is ...


6

One can cut a any material by using a (slightly) softer abrasive material and a soft tool that can press the abrasive against the cutting surface. The tool will simply abrade much faster than the object that is being cut and it will take lots of abrasive and time, but that's OK. This kind of abrasive cutting/grinding is quite common.


5

Yes, is possible. For example, you can see this, water can cut steel.


4

The light rays are crisscrossing in front of you now! $_1$ Do you consider it as soft? It depends on your definition. Your softy light is used to cut hardest materials by using the process called laser cutting. The focused laser beam directed at the material, which then either melts, burns, vaporizes away, or is blown away by a jet of gas.$_2$ ...


3

Firstly, I suspect that oxidation will throw a spanner into any such plan. For metals like aluminum, which have a very high affinity for oxygen, a "virgin" surface will begin to tarnish almost immediately. The second problem is that metals have microstructure. Neighboring crystals in a polycrystalline aggregate such as a metal piece have to satisfy certain ...


2

It depends on your definition of "cutting". Hardness of a material relates to its yield strength - the stress it can sustain without plastic deformation. Push a "soft" material with a sharpened point into a "harder" material, and the tip will go blunt because the soft material deforms. This is why diamond powder is often used to coat grinding wheels etc - ...


2

The space elevator probably deserves an entire series of questions (and I am sure there have been plenty of posts), but if we stick to this particular version, there are a couple of problems with it. First of all, a space elevator needs a counterweight in an orbit that is higher than the areostationary orbit (the Martian equivalent of Earth's geostationary ...


1

A sharp knife is still several molecules thick on the edge; dull blades are even wider. So when you attempt to cut material, it needs to be ripped apart. As explained in other answers, the material either fractures along faults in the lattice, or you separate molecules (as when you cut bread). The only materials where you might split chemical bonds are ...


1

There's a nitinol wire that stiffens when warm and softens when cool. It's been used in various patented heat engine applications. see this reference http://www.imagesco.com/articles/nitinol/09.html


1

I believe a fast-rotating blade can cut a harder material.


1

I believe that it depends on the method of cutting, and on the energy of the material used for cutting. Sure, air can cut steel. If it is heated to several thousand degrees in an arc welder. However, air at the same temperature as the steel is not likely to cut the steel. I believe the method you are asking about is the classic material removal method. ...



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