Sintering grain growth

In the presence of silica, zinc silicate is formed, the sintering process is improved and the increase in grain size is enhanced (Zhuravlev, Volfson, Sheveleva, 1950). Mineralizers, such as fluorite, cryolite and borax, have a similar effect (Zhuravlev, Volfson Sheveleva, 1950). These mineralizers enhance sintering and promote growth in grain size. As a result the sintering temperature can be reduced from 1350 °C to 1150-1200 C. 

Sintering, grain growth Generally produces very small... 

In Chapters 14 and 15 we discussed grain boundaries (GBs) and phase boundaries (PBs), respectively. These two chapters described the interfaces and crystal defects. In Chapter 24 we examined how the movement of GBs can lead to sintering, grain growth, and densification. In this chapter we examine how the movement of PBs leads to transformations and reactions. Some examples of reactions involving the movement of a PB are given in Table 25.1 not all of these are solid-state reactions. 

The comparison of grain sizes for YSZ samples on mono- and poly crystalline AI2O3 substrates are represented in Fig. 2.55. One can see that microstructure is independent of the substrate type for the samples sintered at T < 800 °C. At T > 800 °C the fast growth of grain sizes begins in the films on poly crystalline substrate, while for monocrystalline one this growth starts at T > 1,000 Such behavior could be attributed to different rates of YSZ nucleation, which could be faster for polycrystalline substrate. 

Figure 10.33 Microstructures of a Mo (4 wt% Ni) system showing (a) lateral growth of grains (such as A and B) around a pore (P) for a specimen sintered in three cycles (for 30 min in each cycle) at 1460T (b) after pore filling, preferential growth of a grain (C) into a liquid pocket formed at a pore site, resulting in a more homogeneous microstructure in a specimen sintered in three cycles (60, 30 and 30 min) at 1460°C. (From Ref. 56.)...

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