Naked Science Forum
Non Life Sciences => Technology => Topic started by: Mogen_david on 29/09/2007 00:43:48
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A product for ice skates is promoting a heated skate blade:
Gretzky is plugging a new, battery-warmed skate blade that melts ice to give its wearer — so the endorsements contend — more speed with less work and overall, a better hockey experience.
Hey, is it too late for the Leafs to place an order?
The Thermablade inventor, Calgarian Tory Weber, says the steamy steel is not a novelty item, like Cooperalls, nasal strips or pyramid power. The 43-year-old, who spent more than $5 million over five years to bring his idea to market, believes the “fairly simple physics” behind the electronic blade will revolutionize hockey for competitive players.
“I had a basic understanding that if you put something hot on ice, it’s going to melt and be slippery,’’ said the former steam engineer at the Banff Springs Hotel.
“It’s not super technical. We heat the blade and it creates a thin film of water between the skate blade and the ice and gives the user substantial performance benefits.”
http://www.thestar.com/Sports/article/260714
Another company claims:
When you skate frictional heat is produced. With a conventional blade system this heat is lost, because the steel can not absorb any of it. The resin a t-blade runner is made of however, can store this frictional heat and the thin steel band heats up by up to almost 4?C. This, by the way, is what we call the thermo-effect which gave t-blade its name. How does this make you faster? When gliding over the ice smoothly the blade runs on a thin waterfilm. The more water, the smoother and the faster the glide! Of course a warmer runner melts more ice, meaning the waterfilm you skate on is more stable. The second reason why the t-blade system is faster than conventional runners is the smoothness of the gliding surface. Compared to a t-blade a freshly sharpened steel runner might have edges just as sharp, but the gliding surface is a lot rougher, it is striated from sharpening. This striation makes the waterfilm rip and therefore slows down the skater. The cold rolled steel strip of which the gliding surface of our runners consists is just a lot smoother, since it is never sharpened. Overall the gliding resistance of t-blade is approximately 35% lower than in any conventional blade. This has been proven by scientific tests. When talking to pro players who use t-blades, only few will tell you that they actually feel like they are going that much faster. What they do describe though, is the feeling that skating is more effortless with t-blades and that it saves energy.
http://www.t-blade.com/features.php#more%20speed%20&%20agility
But does it really work that way?
Somorjai's recent discoveries have explained why skaters and pucks slide on the ice. These new findings challenge long-held theories about why ice is slippery. In the past, scientists believed that either pressure or friction melted the ice, creating a water lubricant that allows skates and pucks to slide. Berkeley chemist Michel van Hove, a colleague of Somorjai's, has done calculations which show that skates and pucks do not generate enough pressure to instantly liquefy ice. Somorjai has discovered that ice has a "quasi-fluid layer" that coats the surface of ice and makes it slippery.
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According to Professor Somorjai, the "quasi-fluid" or "water-like" layer exists on the surface of the ice and may be thicker or thinner depending on temperature. At about 250 degrees below zero Fahrenheit (-157 centigrade), the ice has a slippery layer one molecule thick. As the ice is warmed, the number of these slippery layers increases. This may help explain in part the difference between "fast ice" and "slow ice." As the number of layers increases, the players' skates need to "slosh" through more of these "water-like" layers; more friction occurs in these conditions, slowing the players down.
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The nature of ice was examined in "The Ice" section--including the latest findings by chemist Gabor Somorjai. This new information about ice changes the way we look at skating. For a number of years before Somorjai's research, there was a debate as to whether pressure or friction created the water lubricant that was believed to be required for skating. Most scientists seemed to think that it was pressure. According to Somorjai's findings this is not the case. So what do you skate on? Well, actually you skate on vibrating molecules.
http://www.exploratorium.edu/hockey/index.html
So I don't know about you but it sounds like a gimmick to me. But maybe I'm misunderstanding the physics/chemistry of the products and skating. Will heating your skate blades help make you faster?
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Some time take an ice cube and slide it across a frozen pond. Its ridiculous to think that either of those two needs to melt for the slipping to occur. Now take a hockey puck and slide it next to the ice cube on the same pond. No different. The pond is very smooth, so it will have a low coefficient of sliding friction. Much like sliding a dime across my desk. I'd never actually heard the melt/re-freeze theory applied to pucks before.
Skates are different, though. There is a phenomenal amount of pressure when a 200 lbs person puts his weight onto the knife-sharp edge of a single skate. That's plenty of pressure to melt the ice. The sudden pressure changes could easily melt and re-freeze the ice as traditionally thought. The melt/re-freeze also explains why the ice gets so rutted during a hockey game. Although hockey-stops help explain that, too.
But your question is really "should I buy the gimmick skates?" I'd say, don't bother. It's right up there with shaving your legs before a swim meet. How much of a difference do you really think it will make? What's 2/10ths of a second over the length of an ice sheet worth? Will that difference change the outcome of the game? I'm sure your money would be better invested in a book than the skates. If you could anticipate your opponent just a little better you'd have a much bigger advantage than trivially faster skates.
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How narrow are skates?
The ones I have used are about a tenth of an inch thick and about a foot long, so that's just over a square inch. They worked OK with me on them and I'm something like 140 pounds.
That's about 10 atmospheres pressure which is enough to raise the melting point of ice by about a tenth of a degree.
Unless the initial temperature of the ice surface is held constant between 0 and 0.1 C this "melting" simply can't happen.