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As an ice skater I cannot understand why I need to sharpen my blade very often since the hardness of steel is higher than that of ice for sure. Since steel is much harder than ice, how can ice change the shape of steel?

Steeven
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Jason
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    Friction exists, and no material is 100% immune to it. Steel being much harder than ice, and also very tough, can endure a lot of time without needing to resharp, but eventually friction with degrade the edge of steel. – Hydro Guy Oct 19 '17 at 02:27
  • Have you considered corrosion effects? a sharp edge on a piece of steel is particularly susceptible to chemical attack, especially if in contact with water which is even mildly acidic and contains dissolved oxygen. This is an interesting question but it is amenable to experiment. – niels nielsen Oct 19 '17 at 04:28
  • Same question in a different guise: Why do we need to sharpen our knifes if steel is harder than meat and vegetables? – ACuriousMind Oct 19 '17 at 14:34

1 Answers1

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Friction affects both surfaces. The material which is 'harder' is not immune to wear while the 'softer' material wears down. Both materials are worn down, to a different extent. Some of the ice breaks off the floor, some of the steel breaks off the skate.

The relative amount of wear depends (inversely) on the relative hardness of the surfaces. Two 'hard' surfaces made of the same steel wear down equally. The fact that they are equally 'hard' does not mean that they are both immune.

The amount of wear is greatest where the pressure between the surfaces is highest. This is at the sharpest edges or points. Skates need a sharp edge to control sideways motion. But a sharp edge wears down quicker than a blunt edge.

See also Why is it easier to glide on sharp ice skates than on dull skates? and Ice skating, how does it really work?

sammy gerbil
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  • Does it mean I can use sandpaper to scratch or even reshape diamond give enough time? Is the phrase "only diamond can scratch diamond" incorrect? – Jason Feb 04 '18 at 21:58
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    You can use jelly to wear down diamond, but it will take a vary large amount of jelly and a very long time. "Only diamond can scratch diamond" refers to a single scratch. If you keep scratching in the same place with some other material you will eventually wear down the diamond. But it won't look like a scratch mark unless you keep sharpening the other material when the diamond blunts it. – sammy gerbil Feb 04 '18 at 22:08