Lets say you make a simple mechanism, where you have a plate and above the plate is a knife that will scratch against the surface of the plate.
The plate and the knife are made from the same material!
When the plate and knife is plastic, the plate gets scratched and the knife gets blunt!
When the plate and knife is metal, the same thing happened.
When the plate and knife is diamond, the same thing happened.
So the question is... would you need more force to scratch and blunt a diamond using a diamond than you would with metal%26amp;metal or plastic%26amp;plastic? Or would the force required be the same, because of the fact that both interacting materials are the same?|||The diamond would require more force.
A common knife blade is about a 5.5 on the Mohs scale, while diamond, as we all know is the top-ranked 10. That seems fairly obvious. But those are only relative measurements. A "this is harder than that" scale. In this case, it tells us that diamond is about twice as hard as your steel knife, right? 5 x 2 = 10.
When you put it on an *absolute* hardness scale, everything still shakes out in the same order. But the values tell a much different story. Your steel would be about an absolute hardness of 48, while diamond rings in at 1,600! 33 times harder than steel.
Clearly, you need more pressure to scratch a harder thing, even with an equally hard thing. You're trying to gouge the other piece, and it's going to take different pressures to do that.
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