Page 160 - Module DMV20173

8.0 POWDER PROCESSING

ceramic shapes are applicable where higher rates of material removal can

be achieved.
4. Some of the operations involve in Green machining are machining, milling,
sanding, grinding and jiggering.

II) FIRING AND SINTERING OF CERAMICS

1. Drying is a critical stage because of the tendency for the part to warp or

crack from variations in the moisture content and in the thickness of the
part.
2. Control of atmospheric humidity and of ambient temperature is important in
order to reduce warping and cracking.

3. Firing (also called sintering) involves heating the part to an elevated
temperature in a controlled environment.
4. Some shrinkage occurs during firing.
5. Firing gives the ceramic part its strength and hardness. This improvement
in properties results from:

a) the development of a strong bond between particles in the ceramic;
b) reduced porosity.
6. Figure 8.7 shows the mechanism of shrinkage of wet clay caused by the
removal of water during drying.

7. Figure 8.8 shows shrinkage of ceramic product from green body to
sintered body.

Figure 8.7 Shrinkage of wet clay caused by the removal of water during

drying.

BPLK 192 DMV 20173