Helping Hand

On March 14th Ceradyne, Inc. had a press release concerning Fukushima nuclear reactor.  In the statement they offer to supply boron carbide to help control and contain the radiation of the damaged reactor.  Boron has the unique ability of absorbing neutrons.  The plan would be to use boron carbide rod to control the radiation leaving.  Another use for boron carbide would be to enriched boric acid.  The acid would then be dumped into the reactors coolant system causing a reduction in nuclear fission and hopefully reduce the amount of radiation leaving.

Lastly I wish to express my concerns and sympathy for all those effected by this disaster.

Bulletproof Mug: Revisited

In a previous blog post I said that a group of students and I were using alumina and zirconia, common materials used in body armor, to create ceramic mugs.  In another post I showed some pictures detailing the progress we made.  Well now its time for another update.

As you've seen from the pictures in the previous post a solution called a slip was created.  The slip is mixture of water, alumina, zirconia and other material.  When the slip is ready it is poured into molds used to create desired shapes and remove the water.  With this slip we decided to make a M and the Colorado School of Mines' shield.

Don't you just feel the school spirit.

Once the slips are dried they sintered in a furnace at 1500°C for a day.  Unfortunately when removing the the slip from the M mold pieces of it broke off rendering it unusable.  As for the shield we were able to safely remove it from the mold and have it sintered.  When the shield was removed from the furnace it actually turned out pretty good.  Unfortunately I forgot to taken any pictures of it before we started our test.

Our tests consisted of taking the shield dropping and throwing it to the ground.  This is used to copy the actual test for the mug.  At first we started by taking the shield and dropping from table height.  When that did not break it we started throwing it to the ground by hand.  The sample finally broke when we dropped it from the second story of Hill Hall.  See the aftermath.

Its just a scratch.

Okay maybe it a bit more serious than that.

Now we can actually learn a lot by analyzing how and why the shield broke.

Never touch the fracture surfaces.

Although it maybe hard to see from this there are small holes and pore all along the surface where the shield broke.  This means that the slip we made was not completely dense.  These holes act as concentration for forces and act as the origin for cracks to occur.  These holes were most likely caused by air bubbles present in the slip after it was milled.  With this knowledge we will continue to improve our methods to produce the strongest mug possible.  Stay tuned for the next installment of "Bulletproof Mug."

Not Just a One Trick Pony

So I am gonna take a little detour and talk about some other uses of ceramics.  If you have been keeping up with this blog you might remember that ceramics are used in armor because they have high compressive strength, they are relatively light and hard.  You'd probably expect that many of these properties that make ceramics good in armor could be applied to other areas.

Well you're right.  In many crushing and grinding operation including mineral processing ceramics are used.  To break a material you have to hit it with something harder and stronger than it.  When material like alumina is pressed and fired at temperatures around 1400°C they are highly dense, super tough, very hard, and wear resistant.  What better material is there to crush ore?

Ball Mill:  the yellow represents the ore while the grey ball represent the ceramic

Ceramics can also be used for cutting blades.  Many of you have probably seen adds for ceramic knives and said "Why would I pay that much for a stupid knife?"  Well there are actually many advantages to owning a ceramic knife.  The first and probably most important feature is these knives never need to be sharpened.  Second while traditional knives may rust or tarnish ceramic knives won't.  This point may be an advantage or disadvantage depending on its uses but ceramic knives do not bend.  However, a major problem with these knives is they are still somewhat brittle like most other ceramics so if you drop it on the floor it may break.  Still I believe the benefits of ceramic knives outweigh the few disadvantages.

Nice set of ceramic knives good for any kitchen

I think I'll talk about one more use of ceramics outside of armor.  One very important application of ceramics is they are used as building material.  From bricks to concrete these ceramics are commonly used in the construction industry.  They are cheap, abundant and easy to produce.  Yet they still retain high compressive strength which makes them ideal for stacking tall structures.

I hope this post has shown that ceramics have many applications outside of armor and is very important to our lives.  In truth I did not even cover their application in fields like electronics or renewable energy.