What is the difference between amorphous silicon (a-Si) drums and other drums?

Silicon (Latin: silicium) is the chemical element in the periodic table that has the atomic number 14 and the symbol Si. Amorphous silicon is the non-crystalline allotropic form of silicon. Silicon is normally tetrahedral bonded to four neighbouring silicon atoms.
Drums made of amorphous silicon are extremely hard: because of this reason the very long lifecycle of Kyocera drums can be realized. The hardness of the surface is enormous and can be damaged only by impacts on hard edges. Scrape off and/or chip off through pointed articles is also possible, but it´s not a good idea.
It is advantageous that non-toxic abatement occurs in the recycling chain. Most of the material thereby incurred is silicon oxide, also known as sand. Yes, you’re right: sand!