Solid-state sintering - Revision history

W.rheinheimer: /* Summary */

2023-01-10T12:16:57Z

‎Summary

W.rheinheimer at 12:16, 10 January 2023

2023-01-10T12:16:28Z

W.rheinheimer: /* References */

2021-05-03T13:11:45Z

‎References

W.rheinheimer at 12:51, 3 May 2021

2021-05-03T12:51:30Z

W.rheinheimer: /* Effects of the heating rate */

2021-05-03T12:50:25Z

‎Effects of the heating rate

W.rheinheimer: /* Dihedral Angle Effect */

2021-05-03T12:49:31Z

‎Dihedral Angle Effect

W.rheinheimer: /* Dihedral Angle Effect */

2021-05-03T12:48:29Z

‎Dihedral Angle Effect

W.rheinheimer: /* Intermediate Stage */

2021-05-03T12:47:30Z

‎Intermediate Stage

W.rheinheimer: /* Intermediate Stage */

2021-05-03T12:47:04Z

‎Intermediate Stage

W.rheinheimer: /* Intermediate Stage */

2021-05-03T12:46:44Z

‎Intermediate Stage

@@ Line 104: / Line 104: @@
 ==Summary==
-This article is a summary of the basic ideas of solid-state sintering. Many of the features of sintering are well understood. It is clear from the modeling and experiments that particle size is a dominant factor in controlling sintering rates. Other important parameters are the transport mechanisms that dominates sintering in a given case, heating rates and mechanical pressures. Along with an emerging understanding of these parameters, different sintering techniques are being developed, as e.g. SPS sintering which utilizes fast heating rates and a mechanical load to obtain fast densification.
+This article follows a encyclopedia articles (Ref 1) and is a summary of the basic ideas of solid-state sintering. Many of the features of sintering are well understood. It is clear from the modeling and experiments that particle size is a dominant factor in controlling sintering rates. Other important parameters are the transport mechanisms that dominates sintering in a given case, heating rates and mechanical pressures. Along with an emerging understanding of these parameters, different sintering techniques are being developed, as e.g. SPS sintering which utilizes fast heating rates and a mechanical load to obtain fast densification.
 == References==

@@ Line 108: / Line 108: @@
 == References==
 Coble R L 1961 Sintering crystalline solids. J. Appl. Phys. 32, 789–92
 Exner H E 1979 Principles of single phase sintering. In: (ed.) Reviews on Powder Metallurgy and Physical Ceramics. Freund Publishing House, Israel, Vol. 1, pp. 1–4

@@ Line 110: / Line 110: @@
 Coble R L 1961 Sintering crystalline solids. J. Appl. Phys. 32, 789–92
 Exner H E 1979 Principles of single phase sintering. In: (ed.) Reviews on Powder Metallurgy and Physical Ceramics. Freund Publishing House, Israel, Vol. 1, pp. 1–4
 Frenkel J 1945 Viscous flow of crystalline bodies under the action of surface tension. J. Phys. USSR 9, 385
 German R M 1996 Sintering Theory and Practice. Wiley, New York
 Handwerker C A, Blendell J E, Coble R L 1989 Sintering of ceramics. In: Uskokovic D P, Palmour H, Spriggs R M (eds.) Science of Sintering. Plenum Press, New York, pp. 3–37
 Handwerker C A, Blendell J E, Kaysser W A, 1990 Sintering of Advanced Ceramics. Ceramic Transactions, Vol. 7. American Ceramic Society, Westerville, OH
 Johnson D L 1978 Fundamentals of the sintering of ceramics. In: Palmour H, Davis R F, Hare T M (eds.) Processing of Crystalline Ceramics. Plenum Press, New York
 Kingery W D, Francois B 1967 Sintering of crystalline oxides. In: Kuczynski G C, Hooton N A, Gibson C F (eds.) Sintering and Related Phenomena. Gordon and Breach, New York, p. 471
 Kuczynski G C 1949 Self-diffusion in sintering of metal particles.
 Trans. AMIE 185, 169–78
 Rahaman M N 2008 Sintering of Ceramics. CRC Press, New York
 Kang S-J L 2005 Sintering. Elsevier, Boston
 Bordia, Rajendra K.; Kang, Suk-Joong L. & Olevsky, Eugene A. Current understanding and future research directions at the onset of the next century of sintering science and technology Journal of the American Ceramic Society, 2017, 100, 2314-2352
 Castro, Ricardo H. R. & van Benthem, Klaus (ed.) Sintering: mechanisms of convention nanodensification and field assisted processes Springer, 2013

← Older revision		Revision as of 12:51, 3 May 2021
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	==Summary==		==Summary==
	This article is a summary of the basic ideas of solid-state sintering. Many of the features of sintering are well understood. It is clear from the modeling and experiments that particle size is a dominant factor in controlling sintering rates. Other important parameters are the transport mechanisms that dominates sintering in a given case, heating rates and mechanical pressures. Along with an emerging understanding of these parameters, different sintering techniques are being developed, as e.g. SPS sintering which utilizes fast heating rates and a mechanical load to obtain fast densification.		This article is a summary of the basic ideas of solid-state sintering. Many of the features of sintering are well understood. It is clear from the modeling and experiments that particle size is a dominant factor in controlling sintering rates. Other important parameters are the transport mechanisms that dominates sintering in a given case, heating rates and mechanical pressures. Along with an emerging understanding of these parameters, different sintering techniques are being developed, as e.g. SPS sintering which utilizes fast heating rates and a mechanical load to obtain fast densification.
		+
		+
		+	== References==
		+	Coble R L 1961 Sintering crystalline solids. J. Appl. Phys. 32, 789–92
		+	Exner H E 1979 Principles of single phase sintering. In: (ed.) Reviews on Powder Metallurgy and Physical Ceramics. Freund Publishing House, Israel, Vol. 1, pp. 1–4
		+	Frenkel J 1945 Viscous flow of crystalline bodies under the action of surface tension. J. Phys. USSR 9, 385
		+	German R M 1996 Sintering Theory and Practice. Wiley, New York
		+	Handwerker C A, Blendell J E, Coble R L 1989 Sintering of ceramics. In: Uskokovic D P, Palmour H, Spriggs R M (eds.) Science of Sintering. Plenum Press, New York, pp. 3–37
		+	Handwerker C A, Blendell J E, Kaysser W A, 1990 Sintering of Advanced Ceramics. Ceramic Transactions, Vol. 7. American Ceramic Society, Westerville, OH
		+	Johnson D L 1978 Fundamentals of the sintering of ceramics. In: Palmour H, Davis R F, Hare T M (eds.) Processing of Crystalline Ceramics. Plenum Press, New York
		+	Kingery W D, Francois B 1967 Sintering of crystalline oxides. In: Kuczynski G C, Hooton N A, Gibson C F (eds.) Sintering and Related Phenomena. Gordon and Breach, New York, p. 471
		+	Kuczynski G C 1949 Self-diffusion in sintering of metal particles.
		+	Trans. AMIE 185, 169–78
		+	Rahaman M N 2008 Sintering of Ceramics. CRC Press, New York
		+	Kang S-J L 2005 Sintering. Elsevier, Boston
		+	Bordia, Rajendra K.; Kang, Suk-Joong L. & Olevsky, Eugene A. Current understanding and future research directions at the onset of the next century of sintering science and technology Journal of the American Ceramic Society, 2017, 100, 2314-2352
		+	Castro, Ricardo H. R. & van Benthem, Klaus (ed.) Sintering: mechanisms of convention nanodensification and field assisted processes Springer, 2013

← Older revision		Revision as of 12:50, 3 May 2021
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	==Effects of the heating rate==		==Effects of the heating rate==
		+
		+	[[File:Fig9.png\|thumb\|Figure 9 Typical temperature dependence of lattice, grain boundary and surface diffusion coefficients with temperature.]]
	The mass transfer mechanisms during sintering have different temperature dependences due to different thermal activation (Fig. 9). Usually, surface diffusion dominates the sintering process at low temperatures, grain boundary diffusion at intermediate temperatures and volume diffusion at high temperatures. For some materials, some of these processes play no significant role, and some might have additional mass transfer processes as e.g. evaporation and condensation at very high temperatures. As surface diffusion does not result in densification but in coarsening and lowers the driving force for densification, fast heating rates are beneficial for densification as less time is available for surface diffusion coarsening. This rationale resulted in the emergence of the fast firing technique: powder compacts are inserted in a furnace that is pre-heated to the sintering temperature to achieve the fastest possible heating rates. Other techniques that utilize fast heating rates to improve densification are SPS and flash sintering (see below) and laser flash sintering.		The mass transfer mechanisms during sintering have different temperature dependences due to different thermal activation (Fig. 9). Usually, surface diffusion dominates the sintering process at low temperatures, grain boundary diffusion at intermediate temperatures and volume diffusion at high temperatures. For some materials, some of these processes play no significant role, and some might have additional mass transfer processes as e.g. evaporation and condensation at very high temperatures. As surface diffusion does not result in densification but in coarsening and lowers the driving force for densification, fast heating rates are beneficial for densification as less time is available for surface diffusion coarsening. This rationale resulted in the emergence of the fast firing technique: powder compacts are inserted in a furnace that is pre-heated to the sintering temperature to achieve the fastest possible heating rates. Other techniques that utilize fast heating rates to improve densification are SPS and flash sintering (see below) and laser flash sintering.

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 == 	Dihedral Angle Effect ==
 [[File:Fig7.png|thumb|right|Figure 7 Dihedral angle shows the effect of surface energy to grain boundary energy ratio on the shape of pores. Low dihedral angles result in elongated pores and high dihedral angles result in spherical pores.]]
 In the discussion of the initial and intermediate stages it was assumed that the dihedral angle of the grain boundary with the pore surface is 180°, implying that the energy of the grain boundary is very much lower than the energy of the surface. As shown in Fig. 3, many pores have dihedral angles of less than 180°. For a pore on a grain boundary, the dihedral angle, ψ, is defined by the ratio of the grain boundary energy, γb, to the surface energy, γs, such that

← Older revision		Revision as of 12:48, 3 May 2021
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	== Dihedral Angle Effect ==		== Dihedral Angle Effect ==
		+	[[File:Fig7.png\|thumb\|right\|Figure 7 Dihedral angle shows the effect of surface energy to grain boundary energy ratio on the shape of pores. Low dihedral angles result in elongated pores and high dihedral angles result in spherical pores.]]
		+
	In the discussion of the initial and intermediate stages it was assumed that the dihedral angle of the grain boundary with the pore surface is 180°, implying that the energy of the grain boundary is very much lower than the energy of the surface. As shown in Fig. 3, many pores have dihedral angles of less than 180°. For a pore on a grain boundary, the dihedral angle, ψ, is defined by the ratio of the grain boundary energy, γb, to the surface energy, γs, such that		In the discussion of the initial and intermediate stages it was assumed that the dihedral angle of the grain boundary with the pore surface is 180°, implying that the energy of the grain boundary is very much lower than the energy of the surface. As shown in Fig. 3, many pores have dihedral angles of less than 180°. For a pore on a grain boundary, the dihedral angle, ψ, is defined by the ratio of the grain boundary energy, γb, to the surface energy, γs, such that

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 {| class="wikitable"
 |-
-| [[File:Fig6a.png|thumb]]|| [[File:Fig6b.png|thumb]]
+| [[File:Fig6a.png|thumb]]|| [[File:Fig6b.png|thumb|Figure 6 Intermediate stage sintering model with pore channels being formed along the triple junctions.]]
 |}
 == 	Final Stage ==

← Older revision		Revision as of 12:46, 3 May 2021
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	Modifications to this model have be developed to account for a realistic pore-boundary intersection that includes the dihedral angle. The size dependence, G3 or G4, is not changed but additional terms are included to account for the more complicated geometry of the pore surface.		Modifications to this model have be developed to account for a realistic pore-boundary intersection that includes the dihedral angle. The size dependence, G3 or G4, is not changed but additional terms are included to account for the more complicated geometry of the pore surface.
		+
		+	{\| class="wikitable"
		+	\|-
		+	\| [[File:Fig6a.png\|thumb]]\|\| [[File:Fig6b.png\|thumb]]
		+	\|-Figure 6 Intermediate stage sintering model with pore channels being formed along the triple junctions.
		+	\|}

	== Final Stage ==		== Final Stage ==