Question

Discuss the steps in producing a clay-based ceramic from slip clay. Be specific and describe all steps and there effect on the micro-structure of the material - in particular why is the original material called slip clay.

Answer 1

The steps for producing a clay based ceramic is given below :

Step 1: Materials Needed

The materials needed are as follows:

Plaster mold
Large Rubber Bands
Paper or plastic coffee cup
Clay Sponge
Clay Cutting Knife

Step 2:

# Turn your one gallon of Slip ware horizontally and roll back and forth for 5 minutes to get the slip well mixed. You can also shake the gallon up and down but keep in mind it will be heavy.

Step 3:

# Take the empty plastic/paper coffee cup that you gathered from the materials list and fill it up with slip from the 1 gallon container. Once you have done this place it aside for now.

Step 4:

Get your mold ready by making sure the inside is clean and dry. Match up the two halves of the molds by making sure the pinholes are aligned. This will ensure a sealed closure and no leakage when slip is poured into it. This is a mold of a snow man and pumpkin that was casted from plastic toys. Intricate molds and pre-made molds can also be purchased at ceramic supply.

Step 5:

When the two halves of your mold are together fasten them with the large rubber band. Make sure they are nice and snug. This will keep the two halves together and further ensure no leakage.

Step 6:

Once you have placed the rubber band around your mold and secured it, flip the mold hole up.

Step 7:

Take the coffee cup filled with slip and pinch the edge of the cup to make a nice pouring spout. This ensures no spillage and that the slip will flow out of the cup nice and smoothly. We are doing this because the pour hole in our molds are not very large and we want to decrease the amount of spillage.

Step 8:

Pour slip into the mold nice and slowly. Fill the mold until it is almost to the brink.

Step 9:

Once you have finished pouring slip into your mold you must wait for a certain amount of time for a desired thickness to build along the walls of your mold. Below is a timing chart you can refer to for desired thickness. While this is happening you will realize that the slip is getting lower and lower. This is happening because as your slip is building up on the inside of the mold its literally sucking the liquid slip into the mold walls thus resulting in the lowering of the level of slip.

10 mins=1/16 inch thick

15 mins= 1/8 inch thick

30 mins= 3/16 inch thick

You want to stay in the range of 15 to 20 minutes for a decent thickness. For the sake of this tutorial i have allowed the slip to sit in the mold for 15 minutes.

Step 10:

You will begin to see layers of slip building up along the wall of the mold as you keep refilling it.

Step 11:

Once you have waited 15 minutes get prepared to pour out the excess slip into the coffee cup.

Step 12:

Begin to pour out your slip from the mold slowly. Make sure you are not completely flipping the entire mold over but rather tilting it so that the slip pours out from one side of the mold. This allows for cleanliness and ease of pouring. After you are sure all excess slip has been poured out the mold, tilt it against a wall for a couple of minutes to ensure that every last drop of slip has leaked out.

Step 13:

Place your mold hole down onto a piece of paper towel and allow for further drainage for about 10 minutes.

Step 14:

Tilt the mold to its side and allow for drying of the slip inside the mold. Wait approximately 2 hours before releasing the mold.

Step 15:

Once you have waiting for 2 hours you can release the mold to see if the casted piece is ready to fall out. You can determine this by seeing if the casted piece is slightly separating away from the walls of the mold.

Step 16:

Remove the casted piece from the mold by pulling slightly on it. A good cast should allow the piece to just fall out. Do not pull too hard as this may tear the piece. If it is giving you trouble wait a few more minutes before trying again.

Step 17:

Trim away the bottom portion of your cast with the clay cutting knife. This excess piece is always trimmed away as it is build up along the mold where the reservoir was.

Step 18:

Wipe away the seam line and clean up the edge, bottom, and any other inconsistencies in the clay cast.

Step 19: Your Finished!

Effect on the microstructure of the material -

One of the key material factors behind such property improvements is the quality of the materials microstructure.

the effect of microstructure of a Ceramic Affect Its Performance like:

Strength

The strength of an engineering ceramic is typically measured by machining a bar of material into a solid bar 3x4x45 mm which is the subject to a 3 point bending strength test.

Toughness

The toughness of engineering ceramics in simple terms describes the ability of the material to withstand the propagation or movement of a crack throughout the body of the material. It is often measure by using the type of diamond indenter used in conventional hardness tests.

Hardness

Hardness is perhaps the simplest of all property measurements as it is generally measured by the depth of penetration of an indenter into the surface of the material, either a pyramidal indentation in Vickers hardness or a conical indenter in Rockwell hardness testing.

slip. A clay in liquid suspension used decoratively or as a binding agent. Clay slips often have oxides added to them for decorative purposes.