I was wondering if anyone knows some investigation on the effect of particle size distribution on the grain growth. In general only densification are most commonly studied. I was wondering how the grain size will be affected by the particle size apart from the densification. Thanks!
Hello Matias,
Here are some references that you may find useful. The answer will depend on the structure of the grain boundaries. If the grain boundaries are disordered (rough) on an atomic scale, then the ceramic will always undergo normal grain growth. The particle size distribution won't have much effect. If the grain boundaries are ordered (faceted or smooth) on an atomic scale, then the ceramic may undergo normal, abnormal or stagnant (i.e. almost no) grain growth. In this case, a broad particle size distribution will probably cause abnormal grain growth.
Hope that helps,
John.
Thanks a lot, is very useful! I am trying to explain the following, maybe you have some extra comments:
1) My material increasesgrain size linearly with decreasing particle size (particle size distribution unimodal and pretty similar in all but shifted to lower particle sizes) and a given sintering temperature/time which I do not change. Density remains within experimental errors the same.
2) Increasing sintering time (temperature constat) for a given particle size increases the grain size linearly, not exponentially. Density also increases relatively linear although with a little bit more scattering.
If the starting particle size is small, that will increase the driving force for grain growth, which will increase grain size. I'm not sure about question 2), though. Normal grain growth usually displays parabolic time kinetics (average grain size is proportional to the square or cube root of time).
When starting with smaller particles (D2) the driving force is increased. But at the moment when the grain size reaches the value (G2=G1) obtained by the bigger particles (D1), the driving force should be the same so, what makes it go further in term of size. Could it be that the time to reach a given density (or grain size) is smaller when you start with smaller particles? If so, even if the sintering time is the same in both situations, the finer powder will have more "time" on the "densification state" scale. It would be interesting to make shorter sintering time with the finer powder to see at which time it reaches the final grains size of the coarser powder and therefore have an idea of how much more time it had to grow the "extra miles".
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