4.1 Objective:

The objective of sintering to find out the sintered density of a mixture of TiO₂ and Fe powders.

4.2 Introduction:

Sintering is the process of compacting solid mass of material by heat without melting it to the point of liquefaction. Sintering happens naturally in mineral deposits or as a manufacturing process used with metals, ceramics, plastics and other materials. The atoms in the materials diffuse across the boundaries of the particles, fusing the particles together and creating one solid piece. Because the sintering temperature does not have to reach the melting point of the material.

4.3 Properties:

Sintering is effective when the process reduces the porosity and enhances properties such as strength, electrical conductivity, translucency and thermal conductivity.  It may be useful to increase its strength but keep its gas absorbency constant as in filters or catalyst.

4.4 Application:

Sintering is one of the final stages of ceramics and it is used to increase the strength of the compacted materials.                                                                   

Figure 4.1: Muffle furnace (Nebertherm)

4.5 Apparatus Used                                     

1. Compacted mixture powders(TiO₂+Fe)      
2. Gloves
3. Tongs
4. Vernier calipers                            
5.  Weight balance   
6. Muffle furnace                                                                       

                                                                                                                               4.6 Procedure:

Green compacted samples or pellets are placed in muffle furnace for sintering. The pellets are heated at 1050◦c for 90 mints to each sample which is to be sintered and given a same soaking time 90 mints. We weighted it again after sintering and find out the diameter and height of pellets by vernier caliper. Finally, calculate the volume and sintered density of sintered pellets.

Sample Number	Initial Weight Before sintering	Final Weight After sintering	Volume of Sample	Green density	Sintered Density
1	1.5g	1.7g	0.589 cm3	2.54 g/cm3	2.5462g/cm3
2	1.1g	1.2g	0.379 cm3	2.9 g/cm3	2.201g/cm3
3 (Pure MgO)	1.2g	1.1g	0.553  cm3	2.17 g/cm3	1.986g/cm3

4.7 Observation and Calculation:

Figure 4.2: Microstructure of pure MgO (200 x)