space age materials

[ubernew]

I have been hearing about carbon-nano tubes, and that they are much stronger than steel. Then today I had an idea, perhaps this can also create stronger, longer lasting edges! Has any knife maker tried to infuse carbon nano-tubes to knife steel? Would it improve knife strength, durability, etc?

 

[xmtgx]

Right now if they made one out of cbn it would cost in the 10's of thousands considering how long it takes to produce a strand 1/100 of the size of a human hair. It's being developed to be used on the "space elevator" thats predicted to be made in 2050.

If it was mass produced i would still settle with something like ceramic when its perfected since trying to sharpen a cbn blade would shred it.

 

[ubernew]

I don't mean the whole blade made from nano tubes, just add bits of nanotubes into it, like adding a bit of Vanadium or other trace elements to improve knife qualities.

 

[Peter_E_Ryt]

I don't mean the whole blade made from nano tubes, just add bits of nanotubes into it, like adding a bit of Vanadium or other trace elements to improve knife qualities.

Vanadium is an alloying element- it actually changes the steel. From what I know of the nanotubes, it'd work more like laminated a blade, or damascus. However, I don't know if the lamninating process would ruin the nanotubes. The gain would most likely be minimal (if there was any gain at all), and not worth the cost.

 

[Ultraman]

Interesting question and I'm sure a good materials scientist or metallurgist could walk us through with a good qualitative description of the effect of nanotubes on the physical properties of steel. I wonder if a phase diagram can be made of it?

If the usual carbon content is replaced with nanotubes that assume a random orientation (not aligned), I would guess it would increase hardness and maybe toughness. I guess it could take a keen edge assuming the dimensions are on the same order as the normal carbon atoms in a regular carbon steel. If the nanotubes are dimensionally larger, would that result in a blunter edge? Do aligned nanotubes form a laminated surface? Maybe the tubes would provide a differentially hard surface, so the iron or alloy matrix would be softer and thus the nanotubes would form "teeth".

ack, I dunno.

 

[knarfeng]

I have been hearing about carbon-nano tubes, and that they are much stronger than steel. Then today I had an idea, perhaps this can also create stronger, longer lasting edges! Has any knife maker tried to infuse carbon nano-tubes to knife steel? Would it improve knife strength, durability, etc?

No knife maker has tried it to my knowledge. While you might be able to improve the bulk properties of steel such as compression or tensile strength by adding nanotubes, I'm not sure it would improve edge properties.

Nanotubes cannot replace the carbon in steel. Carbon atoms fit (well sort of) within the iron atomic matrix. Small as they are, nanotubes are bigger in diameter than single carbon atoms and cannot fit within the atomic matrix. So you would be left with a two phase material, somewhat like a carbon fiber /epoxy laminate, but perhaps more like FRN (chopped Fiber Reinforced Nylon). Nanotubes could carry stress through the steel, much like carbon fibers do in epoxy/carbon composites. So the bulk strength properties would be improved. Possible improvement in fracture toughness as well. No data, but those are the improvements we see in FRN compared to plain Nylon.

But blade folks are interested in edge properties. A somewhat different beastie from bulk properties.

Nanotubes would not give abrasion resistance like carbides. Carbides are far harder. You might strengthen or toughen the steel so that the edge would not roll, but for most cutting chores my impression is that edge rolling is not an issue for high grade cutlery steels. (Some cutlery maistro please correct this if it is a misconception.)

There is some speculation that Damascus steel got its superior properties from carbon nanotubes, but to my knowledge, it is not proven.
(http://www.nature.com/news/2006/061113/full/061113-11.html) And while damascus steel of the 12th century may have been better than western steel of that time period, I have seen no comparison of the properties of said damascus to those of modern cutlery steels. So I don't think we can say with any certainty that nanotubes are proven to improve modern steel properties because it worked for Damascus steel.

I don't see nanotubes significantly improving edge properties of steel. I have some understanding of some of the basics. But there's a couple of material scientists that hang out here. Metallurgists too. Perhaps one will be kind enough to correct me.

As ultraman said, "ack, I dunno."

 

[xmtgx]

There is some speculation that Damascus steel got its superior properties from carbon nanotubes, but to my knowledge, it is not proven.

I doubt that since there isn't even enough nano tubes in existence to cover 1 square inch.

 

[cybrok]

One thing that would get higher for sure is the price.

 

[spelingmastir]

I develop plastic compounds and work with(among other additives) nanotubes. While nanotubes themselves are very strong and have all of these crazy properties like high strength and high thermal and electrical conductivity, their effects on the properties in various matrices-in my case, thermoplastics- are unique but not quite as amazing as the tubes themselves. And for the record, carbon fibers act as much better physical reinforcements than nanotubes at this time.

As knarfing said, IF these could be incorporated in steel, (and they can't because they would be burnt up at those temperatures) they would only improve the bulk properties. Edge properties come from the hardness of the steel and that comes from the crystal structure of the steel.

How's that for a first post?

 

[OldPhysics]

Vanadium is an alloying element- it actually changes the steel. From what I know of the nanotubes, it'd work more like laminated a blade, or damascus. However, I don't know if the lamninating process would ruin the nanotubes. The gain would most likely be minimal (if there was any gain at all), and not worth the cost.

Single wall...multi wall? Single phase or poly-phase (within a single tube)? Lots of questions here...

Actually, some fairly long fibers can be drawn now. I've seen some very interesting structures woven from these fibers recently.

If you tried to incorporate it in steel, you'd really be wasting your time -- remember that carbon alloys with iron to create steel (and at fairly low temperatures). The nanotubes, no matter what form you used, would simply dissolve into the iron and create one form of steel or another.

 

[Ultraman]

I understand previous poster's contentions that the carbon nanotubes dissolve in steel or do not maintain their integrity due to the heat.

However, a simple google search (granted, it's the internet ), shows carbon nanotubes in damascus steels, and actually, nanotubes were stated in one article as being "naturally formed in the fires of blacksmiths":
QUOTE:
Nanowires and Carbon Nanotubes

They found that the sword contained nanowires and carbon nanotubes. This in itself is not surprising, carbon nanotubes and buckyballs are naturally formed in the fires of a blacksmiths forge and have been found in common steel previously. In this case the nanowires are cementite and are surrounded by the extremely strong carbon nanotubes. All of which is held within the much softer steel matrix.
ENDQUOTE

Here are some links that I still have to peruse:

http://www.azom.com/Details.asp?ArticleID=3602
http://www.rsc.org/chemistryworld/News/2006/November/15110602.asp
http://www.telegraph.co.uk/connected/main.jhtml?xml=/connected/2006/11/16/nscience216.xml
(cites a Nature artcile which from what I know is one of the top scientific journals)
http://www.nature.com/news/2006/061113/full/061113-11.html
(this points out that the nanotubes could have been misidentified or are an artifact of the analytical instrument)

So something still does not compute (with all due respect) - key is finding out the melting temperature of the nanotubes or finding out the temperature they can form to see if they can actually form during temperature and treatment regime of the steel making process.

If the damascus theory has been refuted, then I'll shut up now

Otherwise, this is the part in the seminar when I turn to the person next to me and whisper, "You never know. " beside, ignorance is bliss and it may be a productive avenue for the creative tinkerer or researcher who doesn't know better