Spark Plasma Sintering SPS

This chapter is focused on CS and SPS of high-purity p-SiAlON, which includes the reaction mechanism of CS the physical properties of Vickers hardness and thermal properties and the corrosion resistance properties in different atmospheres. 

In Fig. 4.61, the Young s modulus and hardness are shown for textured alumina obtained by spark plasma sintering [henceforth SPS] of undoped commercial 

The HP relation may be further discussed as follows. A stress concentration exists at or close to the obstacle (a grain boundary in our case). The key factor in the motion of dislocations is the first or leading dislocation in the vicinity of the obstacle. Assume that the leading dislocation has moved a distance, dx all the trailing dislocations will move the same distance. The work done per unit length of dislocation (in Chap. 3) is  

At equilibrium, these equations should be equal and, thus, from Eqs. (3.79) and (3.79a), one obtains  

The internal stress at the head of the pile-up, composed of n dislocations, is n times greater than the applied stress. The back stress of the pile-up, xj, acts on the source to create new dislocations. As long as  

Tg represents an effective stress and Tp is the stress assumed to exist at the head of the pile-up acting at the boundary. Tp is n times larger than the effective stress and n is the number of dislocations in the pile-up. The number of dislocations given as Eq. (3.80), in terms of the effective stress (note that t is given in terms of Tg), is given by  

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SEM image of the fracture surface of 5.7 vol% SWCNT-Fe-Al203 composite densified by spark plasma sintering (SPS) of a mixture of nanometric alumina and ropes of SWCNTs. Reprint from Nature Materials, No. 2, 2002, pp. 38-42, Zhan G.-D., Kuntz J.D., Wan J. and Mukherjee A.K., Single-wall carbon nanotubes as attractive toughening agents in alumina-based nanocomposites, with the permission of Nature Materials and of the authors (http // www.nature.com/nmat/index.html). 

Tokita, M., (2003), Large-size WC/Co functionally graded materials fabricated by spark plasma sintering (SPS) method , Mat. Sci. Forum, 39, 423-425. 

The preparation of the thermoelectric materials has mainly been based on the melt-growth, hot pressing(HP) and hot isostatic pressing(HIP). On the other hand, plasma-activated sintering(PAS) or spark plasma sintering(SPS) has been developed as a new convenient process in the preparation of a variety of FGM [5]. The PAS has been lately applied to prepare thermoelectric materials such as SiGe[6], PbTe, Bi2Tes[7] and semiconductor-electrode joint[8]. 

Meir S, Kalabukhov S, Froumin N, Dariel MP, Frage N (2009) Synthesis and densification of transparent magnesium aluminate spinel by SPS processing. J Am Ceram Soc 92 358—364 Frage N, Cohen S, Meir S, Kalabukhov S, Dariel MP (2007) Spark plasma sintering (SPS) of transparent magnesium-aluminate spineL J Mater Sci 42 3273-3275... 

Another example is the synthesis of YAG Ce (5 %) phosphors [190]. The hydrothermal reaction was carried out at 360 °C for various lime durations, 6-26 h. Single-phase YAG Ce (5 %) was obtained. The powder with reaction time of 22 h was treated by using spark plasma sintering (SPS) in vacuum and in air. No attempt was made to prepare transparent ceramics with the hydrothermally synthesized powders. However, these data could be used as a reference, if one wishes to employ hydrothermal synthesis to produce powders for transparent ceramics. 

Fig. 6.33 Tooling assembly for the spark plasma sintering (SPS) experiments a 15 mm and b 56 mm. Reproduced with permission from [45], Cop5orght 2012, John Wiley Sons...

Fig. 6.36 Computed dependence on the spark plasma sintering SPS) tooling size for 100 °C min (left) and 300 °C min (right) of a and b temperature gradient c and d relative density gradient e and f grain size gradient. The calculation results are given for an intermediate and final time of SPS. Reproduced with permission from [46]. Copyright 2012, John Wiley Sons...

Fabrication of dense p-SiAlON by a combination of combustion synthesis (CS) and spark plasma sintering (SPS). IntermetalUcs, 18, 536—541. 

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