What kind of material are hard drive platters made of?
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Dont pay attention to the previous answer. He is an idiot. The platters are made of a steel alloy, that is magnetic. This is why if you have a powerful magnet, it will erase hard drives. The coating is actually something that INCREASES the magnetism of the platters so that they will hold information better.
The most popular hard drive platter substrate is aluminum. I remember a few years ago before all the HDD makers started consolidating, that companies like Conner, Quantum, Maxtor etc. had produced some HDDs using glass platters, but I don't know if it's still used. On top of the substrate is a very thin-layer coating of ferrous magnetic material (the media layer), which is what the data is actually recorded on. Hope this helps.
