414
J. Sundaram et al.
subsequently, reduces agglomeration in the composite. Due to Zener effect, nanosized particles of TiB 2 which located at boundary strengthened the grain boundary
which improve mechanical properties of composites. Morphology of sample-3 from
Fig. 1, we can infer that the nano-alumina was observed around the grain boundary
which also hinders dislocation of grain [25–27]. During sintering process, particles
of alumina will act as obstacle at the grain boundary which restricts dislocation this
allows grain will move freely within grain boundary leads increase in size of grain.
Rahimian et al. also reported the same that Al 2 O 3 particles acts as obstacle in rearrangement, dislocation and dispersion of the alumina particles which leads to high
porosity without considering sintering consideration [28].
3.2 Density Analysis
The theoretical density was measured with the rule of mixture [29]. Green and
sintered densities were measured by Archimedean principle [30] (Fig. 2).
From Table 4, green densities of sample-1, 2, and 3 were 95.2, 92.1, and 91.6%
when compared with theoretical density. Sintered densities of sample-1, 2 & 3 were
Fig. 2 Billets inside the electrical muffle furnace
Table 4 Comparison of green, sintered, hot pressed and theoretical density
Test
Green
Sintered
Hot pressed
Theoretical
Specimen
density
density
density
density
g/cm 3
g/cm 3
g/cm 3
g/cm 3
Sample-1
2.58
2.63
2.66
2.71
Sample-2
2.59
2.65
2.69
2.81
Sample-3
2.63
2.69
2.73
2.87
J. Sundaram et al.
subsequently, reduces agglomeration in the composite. Due to Zener effect, nanosized particles of TiB 2 which located at boundary strengthened the grain boundary
which improve mechanical properties of composites. Morphology of sample-3 from
Fig. 1, we can infer that the nano-alumina was observed around the grain boundary
which also hinders dislocation of grain [25–27]. During sintering process, particles
of alumina will act as obstacle at the grain boundary which restricts dislocation this
allows grain will move freely within grain boundary leads increase in size of grain.
Rahimian et al. also reported the same that Al 2 O 3 particles acts as obstacle in rearrangement, dislocation and dispersion of the alumina particles which leads to high
porosity without considering sintering consideration [28].
3.2 Density Analysis
The theoretical density was measured with the rule of mixture [29]. Green and
sintered densities were measured by Archimedean principle [30] (Fig. 2).
From Table 4, green densities of sample-1, 2, and 3 were 95.2, 92.1, and 91.6%
when compared with theoretical density. Sintered densities of sample-1, 2 & 3 were
Fig. 2 Billets inside the electrical muffle furnace
Table 4 Comparison of green, sintered, hot pressed and theoretical density
Test
Green
Sintered
Hot pressed
Theoretical
Specimen
density
density
density
density
g/cm 3
g/cm 3
g/cm 3
g/cm 3
Sample-1
2.58
2.63
2.66
2.71
Sample-2
2.59
2.65
2.69
2.81
Sample-3
2.63
2.69
2.73
2.87