[Physics] Is ice harder than steel

ice

While trying to fix our garburator, I found a couple sites claiming that you can sharpen the blades of your garburator by forcing it to process ice.

From my understanding though, that would only be possible if ice was harder than steel.

Obviously ice is far more brittle than steel, but is it harder?

I'm assuming the garburator uses stainless steel, and the ice is at a standard freezer temperature of – 18°C.

Best Answer

Ice has hardness 1.5 on Mohs scale, while steel is 4 to 4.5; see https://en.wikipedia.org/wiki/Mohs_scale_of_mineral_hardness

In the usual course of events one uses a harder substance to sharpen a softer one: corundum sharpening stones work great on steel. It is possible to cut away steel with water, but at ordinary pressure the rate of wear is quite slow, but a high pressure water jet can be used to cut steel and other materials such as your quartz or granite counter tops.

Conclusion: grinding ice in the garbage disposal is, as CuriousOne mentioned, a simple and effective technique for cleaning the blades. This keeps the working surface "sharp" as opposed to covered with gunk.