hello. need to know several things; 1. what exactly is the stuff that i keep reading about called "cementite", and what does it do to the metal on an atomic scale to make it harder and more brittle? 2. how does heat-treating and quenching (ie. heating a steel blade, lets say, and then dunking it into oil, or whatever it is they use) help to harden steel? 3. do they use ceramics for blades nowadays, and if they do, what advantages/disadvantages do they have? 4. i forgot, might be added later on... if you have an answer to any of the above, it would be splendiferous to hear it. thanks.