Materials with 1bn times the strength of steel?

Because of the immense gravity of neutron stars, the outer layers freeze solid to form a crust that surrounds a liquid core. Between the outer layer and the inner core quark–gluon plasma (or quark soup) nuclear pasta forms at matter densities of 10^14 g/cm^3. Protons and neutrons are thought to spatially separate as nuclear attraction and Colombic repulsion forces compete (a type of Spinodal decomposition) and end up forming long cylindrical shapes or flat planes. These have become known as “spaghetti” and “lasagne”—or nuclear pasta.

In a recent PRL paper, it was claimed that this nuclear pasta has a stength of 10 billion times that of steel.

The paper states in abstract a strength of 10^30 ergs/cm^3. 1 erg / cm^3 is equivalent to 0.1 J/m^3. 0.1 J/m^3 is the same as 0.1 Pa. Therefore 10^30 ergs/cm^3 is 10^29 Pa.

Comparing this to the 5.5 GPa stength of Steel Scifer wires… ultimate shear strength = 0.5 * UTS = 2.25 GPa.
(A value for maximum theoretical Shear strength would be 12 GPa I believe).

So now …. 10^29 Pa / 2.25^9 Pa = 3.0 x 10^19 * steel strength = 30.25 Quintillion times the strength of steel.

Tell me what I’m missing here… maybe the paper converted to specific strength over exaggerate their value? What’s the density of nuclear pasta?


Nitinol Stent

This stuff is like magic, it’s metallurgy.

They call this elastic memory, the mechanical properties of nitinol be controlled by composition and prior treatment. Here the stiffness has been decreased such that it’s much lower than we expect in a metal.

Some background about shape memory effect (Materials Science and Metallurgy Department, Univ. of Cambridge):

Example manufacture of knitted stent:

Football world cup crystal distraction

I was captivated while watching a football match by this nice netting. It’s similar to the crystallography of a single graphite layer. Close inspection shows that the netting doesn’t have perfect hexagonal symmetry, as different sides of the hexagon are made up either two or one rope. Also, sadly the football shown doesn’t obviously have the Buckminster Fullerene type stitching that is sometimes used in footballs, a missed opportunity?


Edit: Image shown is from 2014 World Cup, not the current year.

mtex examples with data

I have been doing a bit of play using mtex to look at some EBSD data which I previous exported to .ctf format. mtex is an open source (GPL) software, which written for the commercial matlab software. The mtex package comes along with several examples and tutorials which can be read within matlab or over the http-internet-web.

Example scripts for using mtex are also available to download from the recently published paper “On Three-Dimensional Misorientation Spaces” by Krakow etal. published in Proceedings of the Royal Society A, 473, 2017.

Scripts and EBSD data for the case studies in the paper are available here:

Scripts for producing other figures in the paper (explaining orientation relations etc.) are available from the mtex website here (along with other examples):

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Control of texture in materials using mtex /matlab at Sandvik

Dr Claes Olsson from Sandvik AB’s Materials Technology division explained at the Matlab expo 2016 how Sandvik has used the MTEX toolbox for analyzing and modeling crystallographic textures by means of pole figure and EBSD data. The software has been integrated into the work of the Materials Technology division allowing an auditable methodology for quality control, meeting standards to supply to their nuclear customers (e.g. in case of rolling zircalloy with controlled texture). Initial example of use was with pole figure data collected with a diffractometer, but they have also used the software to analyse EBSD data.
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A video of the presentation can be seen here:
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Slides can be found here:
Mtex is a free toolbox released under the GNU GPL 2, which works inside the commercially available matlab environment.

Angel of the North


The Angel of the North: Image from Wikipedia

At 200 tonnes excluding the concrete piles used to support it, the total cost of The Angel Of The North was said to be £800,000. That means the installed cost for the 200,000 kg was £4 / kg.

The Angel Of The North owes it’s appearance to the weathering steel it is constructed from, these steels are designed to form a stable oxide layer, with a low corrosion rate across the entire surface. This strategy means that it’s possible to have a reasonable service lifetime with a minimum of maintenance, even an initial layer of paint is unnecessary.

Example weathering steel compositions / wt%

Grade C Si Mn P S Cr Cu V Ni
ASTM A242 0.12 0.25–0.75 0.20–0.50 0.01–0.20 0.030 0.50–1.25 0.25–0.55 0.65
ASTM A588 0.16 0.30–0.50 0.80–1.25 0.030 0.030 0.40–0.65 0.25–0.40 0.02–0.10 0.40

Somewhat uniquely for steels, the initial rust layer protects the steel underneath from further deterioration, eliminating the need for paint. This depends on environmental conditions, too much humidity too often mean that the rust layer never reaches a stable point. This can lead to corrosion and loss of integrity.

edX is a really fun site. I tried this course: CS50 introduction to computer science. It seems like a really good course, I attempted to study it a couple of times and registered for the certificate so I would have some skin in the game, but I still didn’t manage to finish, although this course has a very engaging presentation and it very well made. I think trying to do the course along with the regular teaching schedule is probably a better idea than going self-paced for me.

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I had fun pretending to learn about steel on the course “introduction to steel which is presented by Mark Miodownik. This is a short course, if you want a basic introduction to steel, or to look at some of the mechanics of an edx course this course can be completed quickly.

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Finally I followed this course from MIT which teaches computer science and programming using the python language, It’s really a good course if you found you are programming already but have never studied programming formally (or even if you intend to program in future!). It took me a whole bunch of time each week to work through the problem sets, maybe try not having too much spare time for it to gobble up. Problem sets and exam questions are completed in python, I think they recommend the spyder ide, and then loaded for automatic marking.

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Now I should be learning biochemistry, so I have this to learn from (and Alberts’ The Cell).

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