Ceramics

How Ostwald ripening effect modifies sintering process?

Oswald effect: the small grains become smaller, and the large larger, it leads to increase medium grains size

The role of liquid phase during sintering

Reduction of sintering rate

List the techniques of sintering methods

• Solid-state sintering • Liquid-state sintering • Reaction sintering • Constrained sintering

Give the advantages of hot press-sintering

• Low level of porosity in obtained ceramics, • Gives high dimensional precision of produced ceramics, • Low strains help to suppress grain growth in produced ceramics, • Allows to sinter powders with high melting temperatures (rougly up 2000oC), • Allows to produceMMC composites and cermetallics.

Why hot-press sintering is not a common industrial practice?

Hot-press sintering isn’t a common industrial practice because of lack of proper material for dies manufacturing. In common use are dies made of graphite,because it conducts heat/electricity and stands high temperatures used in process. Unfortunately mechanical properties of graphite are low and its wear resistance is even worse. Because of that there is big need for frequent exchange of dies and it makes cost of the process quite high.

Give examples (2) of new methods for fast sintering

- Spark plasma sintering - Microwave sintering