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.|
|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."