Glad you like. *grin*
Here's an article that maybe explains it a little better than I did: www.ndt-ed.org/EducationResources/CommunityCollege/Materials/Mechanical/Toughness.htm

Tests designed to measure toughness are explained here: www.engineersedge.com/material_science/toughness.htm

Porcelain is actually pretty cool stuff- depending on what you add to it, you can modify a lot of its physical properties. And, of course, it can handle ridiculously high temperatures.

Glass is fascinating to me in a different way- it's not a homogeneous material, because it's essentially a supercooled liquid that has no crystalline structure. Actual crystal is glass that was cooled slowly so it could form a crystalline lattice, and is much better at dealing with heat than glass is. The problem with glass is that small pockets within it will expand faster than other parts, resulting in fractures. If there's a lot of internal stress on the glass (which there will be if it's heated a lot) you get catastrophic failure. Wanna see something really dramatic? Put a Pyrex pan on top of the burner of a stove, empty, and turn on the burner. It won't just crack it will explode. (My sister discovered this one night as my family was eating dinner, when she turned on the wrong burner. I thought Mom shat herself.)

Ice is another fascinating one. Know why you don't want to freeze water in a glass container? Because the ice expands as it forms. Why? Because all of those little molecules, which are shaped like boomerangs, go from being jumbled together to trying to form hexagons- which takes up more space. Since glass is brittle and fails quickly under tension, your glass jar will explode in your freezer every time.

Thus endeth the materials lecture for the morning. I need to go get lunch.
( The Resident Loon Not a demographic. Do not measure., Thu 16 Apr 2009, 17:03, Reply)