Progress of Porous Silicon Nitride Ceramics Prepared via Self-propagating High Temperature Synthesis

doi:10.15541/jim20220019

Abstract

Abstract:

Porous silicon nitride (Si₃N₄) ceramics can be widely used in various fields, such as sound and shock absorption, filtration and so on, due to its high porosity and outstanding properties of ceramics. However, conventional preparation methods, such as gas-pressure/pressureless sintering, sintering reaction-bonded sintering and carbothermal reduction sintering, perform long sintering time, high energy consumption and high equipment requirements, which makes the preparation of porous Si₃N₄ ceramics expensive. Therefore, it is of great importance to explore a rapid and low-cost preparation method. In recent years, the direct preparation of porous Si₃N₄ ceramics by self-propagating high temperature synthesis (SHS) has showed great potential of which the heat released from the nitridation of Si powder could be used for the in-situ sintering of porous Si₃N₄ ceramics. In present paper, researches relating to the initiation of the SHS reaction, and microstructural evolution, mechanical properties, and reliability of the fabricated Si₃N₄ ceramics are summerized systematically. Porous Si₃N₄ ceramics with complete nitridation, excellent grain morphology and outstanding mechanical properties and reliability are obtained by adjusting raw materials and process parameters. Furthermore, the relationship between properties of grain boundary phase and high-temperature mechanical properties of SHS-fabricated porous Si₃N₄ ceramics is reviewed. Finally, the development direction of the self-propagating high temperature synthesis of porous Si₃N₄ ceramics is prospected.

Key words: self-propagating high-temperature synthesis, silicon nitride, microstructure, mechanical property, review

CLC Number:

TQ174

ZHANG Ye, ZENG Yuping. Progress of Porous Silicon Nitride Ceramics Prepared via Self-propagating High Temperature Synthesis[J]. Journal of Inorganic Materials, 2022, 37(8): 853-864.

Figures/Tables 13

Fig. 1 Optical picture (a) and amplified microstructures (b-d) of the porous Si3N4 ceramics prepared by gel-casting and SHS[32]

Fig. 2 Schematic illustration of the fabrication of porous Si3N4 ceramics by SHS[47]

Table 1 Composition of raw materials, parameters of SHS process and properties of the fabricated samples

Si/g	Si₃N₄/g	Y₂O₃/g	Combustion temperature/℃	Reaction time/s	Open porosity/%	Shrinkage/%	Ref.
30-45	70-55	2	1870-2050	30-13	40.5-45.8	/	[47]
30-70	70-30	5	1820-1982	/	50.0-60.0	2.8-3.4	[48]

Fig 3 Microstructures of the porous Si3N4 ceramics fabricated by different (p) pressures of N2 gas (p) and average particle sizes of Si powder (d50)[46] (a) p=3 MPa, d50=2.7 μm; (b) p=5 MPa, d50=2.7 μm; (c) p=7 MPa, d50=2.7μm; (d) p=9 MPa, d50=2.7 μm; (e) p=5 MPa, d50=1.3 μm; (f) p=5 MPa, d50=2.7 μm; (g) p=5 MPa, d50=4.5 μm; (h) p=5 MPa, d50=8.7 μm

Fig. 4 Schematic of the formation mechanism of porous Si3N4 starting from Si with different particle sizes[46]

Fig. 5 Microstructures of different areas of the SHS-fabricated Si3N4 ceramics[59]

Fig. 6 Weibull plots of flexural strength for samples prepared with different types of Si3N4 diluent and shaping pressures[59] (Sample ST uses Si3N4 diluent with coarse particle size and high β phase while sample SA uses Si3N4 diluent with fine particle size and high α phase, -X represents the shaping pressure)

Table 2 Correlation coefficient and Weibull modulus of samples obtained with two different Si3N4 powders and varied shaping pressures[59]

	SA-50	SA-100	SA-150	SA-200	ST-50	ST-100	ST-150	ST-200	Ref.[63-64]
R²	0.99	0.96	0.99	0.97	0.96	0.90	0.96	0.99	-
m	11.4	9.3	8.8	5.7	11.4	16.0	17.2	11.0	10.6-20.9

Fig. 7 Relationship between flexural strength and porosity of ceramics prepared by different methods SSN represents sintering Si3N4 by pressureless or gas pressure sintering[10,65⇓⇓⇓⇓⇓⇓⇓⇓-74]; SRBSN represents sintering reaction-bonded Si3N4 [75⇓⇓⇓⇓⇓⇓⇓-83]; CRS represents Si3N4 fabricated by carbothermal reduction sintering[16,84⇓-86]; SHS represents Si3N4 fabricated by self-propagating high temperature synthesis[46⇓-48,56,59-60]

Fig. 8 Room-temperature and high-temperature flexural strength of the fabricated porous Si3N4 ceramics with different sintering additives[56]

Fig. 9 Stress-strain curves of the obtained porous Si3N4 ceramics during fracture at 1400 ℃[56]

Fig. 10 Microstructures and average grain sizes of the SHS-fabricated Si3N4 ceramics prepared with different Y2O3 mass content as sintering additive[62] (a) 0; (b) 0.4%; (c) 0.8%; (d) 1.2%; (e) 1.6%. L, D, AR represents average grain length, average grain diameter, and average aspect ratio respectively

Fig. 11 Room-temperature and high-temperature flexural strength of the fabricated porous Si3N4 ceramics as function of sintering additives addition[62]

References 90

[1]	WANG W D, YAO D X, CHEN H B, et al. ZrSi₂-MgO as novel additives for high thermal conductivity of β-Si₃N₄ ceramics. J. Am. Ceram. Soc., 2020, 103(3): 2090-2100. DOI URL
[2]	WANG W, YAO D, LIANG H, et al. Effect of in-situ formed Y₂O₃ by metal hydride reduction reaction on thermal conductivity of β-Si₃N₄ ceramics. J. Eur. Ceram. Soc., 2020, 40(15): 5316-5323. DOI URL
[3]	WANG W, YAO D, LIANG H, et al. Effect of the binary nonoxide additives on the densification behavior and thermal conductivity of Si₃N₄ ceramics. J. Am. Ceram. Soc., 2020, 103(10): 5891-5899. DOI URL
[4]	WANG W, YAO D, LIANG H, et al. Novel silicothermic reduction method to obtain Si₃N₄ ceramics with enhanced thermal conductivity and fracture toughness. J. Eur. Ceram. Soc., 2021, 41(2): 1735-1738. DOI URL
[5]	BECHER P F, PAINTER G S, SHIBATA N, et al. Effects of rare- earth (RE) intergranular adsorption on the phase transformation, microstructure evolution, and mechanical properties in silicon nitride with RE₂O₃ + MgO additives: RE=La, Gd, and Lu. J. Am. Ceram. Soc., 2008, 91(7): 2328-2336. DOI URL
[6]	TATARKO P, KAŠIAROVA M, DUSZA J, et al. Influence of rare- earth oxide additives on the oxidation resistance of Si₃N₄-SiC nanocomposites. J. Eur. Ceram. Soc., 2013, 33(12): 2259-2268. DOI URL
[7]	ROUXEL T, SANGLEBOEUF J C, HUGER M, et al. Temperature dependence of Young's modulus in Si₃N₄-based ceramics: roles of sintering additives and of SiC-particle content. Acta Mater., 2002, 50(7): 1669-1682. DOI URL
[8]	LI X Q, YAO D X, ZUO K H, et al. Fabrication, microstructural characterization and gas permeability behavior of porous silicon nitride ceramics with controllable pore structures. J. Eur. Ceram. Soc., 2019, 39(9): 2855-2861. DOI URL
[9]	LI X Q, YAO D X, ZUO K H, et al. Microstructure and gas permeation performance of porous silicon nitride ceramics with unidirectionally aligned channels. J. Am. Ceram. Soc., 2020, 103(11): 6565-6574. DOI URL
[10]	XIA Y F, ZENG Y P, JIANG D L. Mechanical and dielectric properties of porous Si₃N₄ ceramics using PMMA as pore former. Ceram. Int., 2011, 37(8): 3775-3779. DOI URL
[11]	PRADEILLES N, RECORD M C, GRANIER D, et al. Synthesis of β-SiAlON: a combined method using Sol-Gel and SHS processes. Ceram. Int., 2008, 34(5): 1189-1194. DOI URL
[12]	JENNINGS H M, RICHMAN M H. Structure, formation mechanisms and kinetics of reaction-bonded silicon-nitride. J. Mater. Sci., 1976, 11(11): 2087-2098. DOI URL
[13]	ZIEGLER G, HEINRICH J, WOTTING G. Relationships between processing, microstructure and properties of dense and reaction- bonded silicon-nitride. J. Mater. Sci., 1987, 22(9): 3041-3086. DOI URL
[14]	MATSUNAGA C, ZHOU Y, KUSANO D, et al. Nitridation behavior of silicon powder compacts of various thicknesses with Y₂O₃ and MgO as sintering additives. Int. J. Appl. Ceram, 2017, 14(6): 1157-1163.
[15]	SHAN S Y, YANG J F, GAO J Q, et al. Porous silicon nitride ceramics prepared by reduction-nitridation of silica. J. Am. Ceram. Soc., 2005, 88 (9): 2594-2596. DOI URL
[16]	YANG J F, SHAN S Y, JANSSEN R, et al. Synthesis of fibrous β-Si₃N₄ structured porous ceramics using carbothermal nitridation of silica. Acta Mater., 2005, 53(10): 2981-2990. DOI URL
[17]	ZHI Q, WANG B, ZHAO S, et al. Synthesis and mechanical properties of highly porous ultrafine-grain Si₃N₄ ceramics via carbothermal reduction-nitridation combined with liquid phase sintering. Ceram. Int., 2019, 45(17): 21359-21364. DOI URL
[18]	MUNIR Z A, HOLT J B, The combustion synthesis of refractory nitrides. J. Mater. Sci., 1987, 22(2): 710-714. DOI URL
[19]	ZAKI Z, MOSTAFA N, AHMED Y, et al. Processing of high- density magnesia spinel electro-conducting ceramic composite and its oxidation at 1400 ℃. Int. J. Appl. Ceram, 2016, 13(4): 662-669.
[20]	ADACHI S, WADA T, MIHARA T, et al. High-pressure self- combustion sintering of alumina titanium carbide ceramic composite. J. Am. Ceram. Soc., 1990, 73(5): 1451-1452. DOI URL
[21]	BHAUMIK S K, DIVAKAR C, SINGH A K, et al. Synthesis and sintering of TiB₂ and TiB₂-TiC composite under high pressure. Mater. Sci. Eng., A, 2000, 279(1/2): 275-281. DOI URL
[22]	BHAUMIK S K, DIVAKAR C, DEVI S U, et al. Synthesis and sintering of SiC under high pressure and high temperature. J. Mater. Res., 1999, 14(3): 906-911. DOI URL
[23]	梁宝岩, 张艳丽, 张旺玺, 等. Ti/Al/TiN体系自蔓延高温合成钛铝氮复合材料. 粉末冶金材料科学与工程, 2014, 105(4): 417-420.
[24]	CINCOTTI A, LICHERI R, LOCCI A M, et al. A review on combustion synthesis of novel materials: recent experimental and modeling results. J. Chem. Technol. Biotechnol., 2003, 78(2/3): 122-127.
[25]	TIAN Z B, ZHANG J, SUN S Y, et al. Combustion synthesis of α-Si₃N₄ with the addition of NH₄Cl. Ceram. Int., 2018, 44(16): 20591-20594. DOI URL
[26]	GE Y Y, SUN S Y, WANG Q, et al. Effect of Fe-contained species on the preparation of α-Si₃N₄ fibers in combustion synthesis. J. Am. Ceram. Soc., 2016, 99(4): 1464-1471. DOI URL
[27]	WU X M, LIU G H, LI J Q, et al. Combustion synthesis of ZrN and AlN using Si₃N₄ and BN as solid nitrogen sources. Ceram. Int., 2018, 44(10): 11914-11917. DOI URL
[28]	HIRANAKA A, YI X, SAITO G, et al. Effects of Al particle size and nitrogen pressure on AlN combustion synthesis. Ceram. Int., 2017, 43(13): 9872-9876. DOI URL
[29]	SHAHIEN M, RADWAN M, KIRIHARA S, et al. Combustion synthesis of single-phase β-SiAlONs (z=2-4). J. Eur. Ceram. Soc., 2010, 30(9): 1925-1930. DOI URL
[30]	WANG Q, GE Y Y, CHEN Y, et al. SHS of Eu²⁺-doped β-SiAlON phosphors: impacts of N₂ pressure and Si particle size. Ceram. Int., 2017, 43(5): 4456-4461. DOI URL
[31]	XU J K, HU Z L, HAN Y, et al. Combustion synthesis of MgSiN₂ powders and Si₃N₄-MgSiN₂ composite powders: effects of processing parameters. J. Am. Ceram. Soc., 2020, 103(1): 122-135. DOI URL
[32]	CUI W, ZHU Y, GE Y Y, et al. Effects of nitrogen pressure and diluent content on the morphology of gel-cast-foam-assisted combustion synthesis of elongated β-Si₃N₄ particles. Ceram. Int., 2014, 40(8): 12553-12560. DOI URL
[33]	CANO I G, BOROVINSKAYA I P, RODRIGUEZ M A, et al. Effect of dilution and porosity on self-propagating high-temperature synthesis of silicon nitride. J. Am. Ceram. Soc., 2002, 85(9): 2209-2211. DOI URL
[34]	YANG J H, HAN L S, CHEN Y X, et al. Effects of pelletization of reactants and diluents on the combustion synthesis of Si₃N₄ powder. J. Alloys Compd., 2012, 511(1): 81-84. DOI URL
[35]	WON H I, WON C W, NERSISYAN H H, et al. Salt-assisted combustion synthesis of silicon nitride with high α-phase content. J. Alloys Compd., 2010, 496(1/2): 656-659. DOI URL
[36]	CHEN Y X, LI J T, DU J S. Cost effective combustion synthesis of silicon nitride. Mater. Res. Bull., 2008, 43(6): 1598-1606. DOI URL
[37]	CANO I G, BAELO S P, RODRIGUEZ M A, et al. Self-propagating high temperature-synthesis of Si₃N₄: role of ammonium salt addition. J. Eur. Ceram. Soc., 2001, 21(3): 291-295. DOI URL
[38]	CHEN D Y, ZHANG B L, ZHUANG H R, et al. Synthesis of β-Si₃N₄ whiskers by SHS. Mater. Res. Bull., 2002, 37(8): 1481-1485. DOI URL
[39]	PENG G H, JIANG G J, ZHUANG H R, et al. Fabrication of β-Si₃N₄ whiskers by combustion synthesis with MgSiN₂ as additives. Mater. Res. Bull., 2005, 40(12): 2139-2143. DOI URL
[40]	GERMAN R, SURI P, PARK S, Review: liquid phase sintering. J. Mater. Sci., 2009, 44(1): 1-39. DOI URL
[41]	KRSTIC Z, KRSTIC V D. Silicon nitride: the engineering material of the future. J. Mater. Sci., 2011, 47(2): 535-552. DOI URL
[42]	ZIEGLER A, IDROBO J C, CINIBULK M K, et al. Interface structure and atomic bonding characteristics in silicon nitride ceramics. Science, 2004, 306(5702): 1768-1770. DOI URL
[43]	SHIBATA N, PENNYCOOK S J, GOSNELL T R, et al. Observation of rare-earth segregation in silicon nitride ceramics at subnanometre dimensions. Nature, 2004, 428(6984): 730-733. DOI URL
[44]	CHEN D, ZHANG B, ZHUANG H, et al. Combustion synthesis of network silicon nitride porous ceramics. Ceram. Int., 2003, 29(4): 363-364. DOI URL
[45]	LI W K, CHEN D Y, ZHANG B L, et al. Effect of rare-earth oxide additives on the morphology of combustion synthesized rod-like β-Si₃N₄crystals. Mater. Lett., 2004, 58(17/18): 2322-2325.
[46]	ZHANG Y, YAO D, ZUO K, et al. Effects of N₂ pressure and Si particle size on mechanical properties of porous Si₃N₄ ceramics prepared via SHS. J. Eur. Ceram. Soc., 2020, 40(13): 4454-4461. DOI URL
[47]	ZHANG Y, YAO D, ZUO K, et al. Fabrication and mechanical properties of porous Si₃N₄ ceramics prepared via SHS. Ceram. Int., 2019, 45(12): 14867-14872. DOI URL
[48]	WANG L, HE G, YANG Z, et al. Combustion synthesis of high flexural strength, low linear shrinkage and machinable porous β-Si₃N₄ ceramics. J. Eur. Ceram. Soc., 2020, 41(4): 2395-2399. DOI URL
[49]	CAO Y G, EG C C, ZHOU Z J, et al. Combustion synthesis of α-Si₃N₄ whiskers. J. Mater. Res., 1999, 14(3): 876-880. DOI URL
[50]	WAKIHARA T, YABUKI H, TATAMI J, et al. In situ measurement of shrinkage during postreaction sintering of reaction-bonded silicon nitride. J. Am. Ceram. Soc., 2008, 91(10): 3413-3415. DOI URL
[51]	WANG C, QIAO R Q, CHEN L J. Fabrication and erosion resistance of dense α-Si₃N₄/SiAlON coating on porous Si₃N₄ ceramic. RSC Adv., 2016, 6(68): 63801-63808. DOI URL
[52]	LEE J S, MUN J H, HAN B D, et al. Effect of raw-Si particle size on the properties of sintered reaction-bonded silicon nitride. Ceram. Int., 2004, 30(6): 965-976. DOI URL
[53]	KRAMER M, HOFFMANN M J, PETZOW G. Grain-growth studies of silicon-nitride dispersed in an oxynitride glass. J. Am. Ceram. Soc., 1993, 76(11): 2778-2784. DOI URL
[54]	CHEN S L, WANG L, HE G, et al. Microstructure and properties of porous Si₃N₄ ceramics by gelcasting-self-propagating high- temperature synthesis (SHS). J. Adv. Ceram., 2021, 11: 172-183. DOI URL
[55]	ZHANG Y, YAO D, ZUO K, et al. A novel route for the fabrication of porous Si₃N₄ ceramics with unidirectionally aligned channels. Mater. Lett., 2020, 276: 128246.
[56]	ZHANG Y, YAO D, ZUO K, et al. Effects of different types of sintering additives and post-heat treatment (PHT) on the mechanical properties of SHS-fabricated Si₃N₄ ceramics. Ceram. Int., 2021, 47(16): 22461-22467. DOI URL
[57]	GRIFFITH A A. The phenomena of rupture and flow in solids. Philos. Trans. Royal Soc., 1920, 221: 163-198.
[58]	DING H, HU Y, LI X, et al. Microstructure, mechanical properties and sintering mechanism of pressureless-sintered porous Si₃N₄ ceramics with YbF₃-MgF₂ composite sintering aids. Ceram. Int., 2020, 46(2): 2558-2564. DOI URL
[59]	ZHANG Y, YAO D, ZUO K, et al. Self-propagating high temperature synthesis (SHS) of porous Si₃N₄-based ceramics with considerable dimensions and study on mechanical properties and oxidation behavior. J. Eur. Ceram. Soc., 2021, 41(8): 4452-4461. DOI URL
[60]	HU Y, ZUO K, XIA Y, et al. Microstructure and permeability of porous Si₃N₄ supports prepared via SHS. Ceram. Int., 2021, 47(2): 1571-1577. DOI URL
[61]	KAWAI C. Effect of grain size distribution on the strength of porous Si₃N₄ ceramics composed of elongated β-Si₃N₄ grains. J. Mater. Sci., 2001, 36(23): 5713-5717. DOI URL
[62]	ZHANG Y, YU X, GU H, et al. Microstructure evolution and high-temperature mechanical properties of porous Si₃N₄ ceramics prepared by SHS with a small amount of Y₂O₃ addition. Ceram. Int., 2021, 47(4): 5656-5662. DOI URL
[63]	YU F L, WANG H R, YANG J F, et al. Effects of organic additives on microstructure and mechanical properties of porous Si₃N₄ ceramics. Bull. Mater. Sci., 2010, 33(3): 285-291. DOI URL
[64]	KALEMTAS A, TOPATES G, OZCOBAN H, et al. Mechanical characterization of highly porous β-Si₃N₄ ceramics fabricated via partial sintering & starch addition. J. Eur. Ceram. Soc., 2013, 33(9): 1507-1515. DOI URL
[65]	KAWAI C, YAMAKAWA A. Effect of porosity and microstructure on the strength of Si₃N₄: designed microstructure for high strength, high thermal shock resistance, and facile machining. J. Am. Ceram. Soc., 1997, 80(10): 2705-2708. DOI URL
[66]	YANG J F, DENG Z Y, OHJI T. Fabrication and characterisation of porous silicon nitride ceramics using Yb₂O₃ as sintering additive. J. Eur. Ceram. Soc., 2003, 23(2): 371-378. DOI URL
[67]	YIN X W, LI X M, ZHANG L T, et al. Microstructure and mechanical properties of Lu₂O₃-doped porous silicon nitride ceramics using phenolic resin as pore-forming agent. Int. J. Appl. Ceram, 2010, 7(3): 391-399.
[68]	LI X M, YIN X W, ZHANG L T, et al. Microstructure and properties of porous Si₃N₄ ceramics with a dense surface. Int. J. Appl. Ceram, 2011, 8(3): 627-636.
[69]	YUE J S, DONG B C, WANG H J. Porous Si₃N₄ fabricated by phase separation method using benzoic acid as pore-forming agent. J. Am. Ceram. Soc., 2011, 94(7): 1989-1991. DOI URL
[70]	DING H H, ZHAO Z H, QI T, et al. High α-β phase transition and properties of YbF₃-added porous Si₃N₄ ceramics obtained by low temperature pressureless sintering. Int. J. Refract. Hard. Met., 2019, 78: 131-137. DOI URL
[71]	JIANG G P, YANG J F, GAO J Q, et al. Porous silicon nitride ceramics prepared by extrusion using starch as binder. J. Am. Ceram. Soc., 2008, 91(11): 3510-3516. DOI URL
[72]	LIU X H, HUANG Z Y, GE Q M, et al. Microstructure and mechanical properties of silicon nitride ceramics prepared by pressureless sintering with MgO-Al₂O₃-SiO₂ as sintering additive. J. Eur. Ceram. Soc., 2005, 25(14): 3353-3359. DOI URL
[73]	YANG J, YANG J F, SHAN S Y, et al. Effect of sintering additives on microstructure and mechanical properties of porous silicon nitride ceramics. J. Am. Ceram. Soc., 2006, 89(12): 3843-3845. DOI URL
[74]	FAN L, ZHOU M, WANG H J, et al. Low-temperature preparation of β-Si₃N₄ porous ceramics with a small amount of Li₂O-Y₂O₃. J. Am. Ceram. Soc., 2014, 97(5): 1371-1374. DOI URL
[75]	YAO D, CHEN H, ZUO K H, et al. High temperature mechanical properties of porous Si₃N₄ prepared via SRBSN. Ceram. Int., 2018, 44(11): 11966-11971. DOI URL
[76]	YAO D X, XIA Y F, ZENG Y P. et al. Porous Si₃N₄ ceramics prepared via slip casting of Si and reaction bonded silicon nitride. Ceram. Int., 2011, 37(8): 3071-3076. DOI URL
[77]	YAO D X, XIA Y F, ZUO K H, et al. The effect of fabrication parameters on the mechanical properties of sintered reaction bonded porous Si₃N₄ ceramics. J. Eur. Ceram. Soc., 2014, 34(15): 3461-3467. DOI URL
[78]	YAO D X, ZENG Y P. High flexural strength porous silicon nitride prepared via nitridation of silicon powder. J. Inorg. Mater., 2011, 26(4): 422-426. DOI URL
[79]	YAO D X, ZENG Y P, ZUO K H, et al. The effects of BN addition on the mechanical properties of porous Si₃N₄/BN ceramics prepared via nitridation of silicon powder. J. Am. Ceram. Soc., 2011, 94(3): 666-670. DOI URL
[80]	YAO D X, ZENG Y P, ZUO K H, et al. Porous Si₃N₄ ceramics prepared via nitridation of Si powder with Si₃N₄ Filler and postsintering. Int. J. Appl. Ceram., 2012, 9(2): 239-245.
[81]	HU H L, YAO D X, XIA Y F, et al. Porous Si₃N₄/SiC ceramics prepared via nitridation of Si powder with SiC addition. Int. J. Appl. Ceram. 2014, 11(5): 845-850.
[82]	HU H L, ZENG Y P, ZUO K H, et al. Synthesis of porous Si₃N₄/SiC ceramics with rapid nitridation of silicon. J. Eur. Ceram. Soc., 2015, 35(14): 3781-3787. DOI URL
[83]	HU H L, ZENG Y P, XIA Y F, et al. Rapid fabrication of porous Si₃N₄/SiC ceramics via nitridation of silicon powder with ZrO₂ as catalyst. Ceram. Int., 2014, 40(5): 7579-7582. DOI URL
[84]	LU Y, YANG J F, LU W Z, et al. Porous silicon nitride ceramics fabricated by carbothermal reduction-reaction bonding. Mater. Manuf. Processes, 2011, 26(6): 855-861. DOI URL
[85]	SHAN S Y, JIA Q M, JIANG L H, et al. Microstructure control and mechanical properties of porous silicon nitride ceramics. Ceram. Int., 2009, 35(8): 3371-3374. DOI URL
[86]	SHAN S Y, YANG J F, GAO J Q, et al. Fabrication of porous silicon nitride with high porosity. Key Eng. Mater., 2007, 336-338: 1105-1108. DOI URL
[87]	LU H H, HUANG J L, Effect of Y₂O₃ and Yb₂O₃ on the microstructure and mechanical properties of silicon nitride. Ceram. Int., 2001, 27(6): 621-628. DOI URL
[88]	KLEMM H, PEZZOTTI G. Fracture toughness and time-dependent strength behavior of low-doped silicon nitrides for applications at 1400 ℃. J. Am. Ceram. Soc., 1994, 77(2): 553-561. DOI URL
[89]	LANGE F F. High-temperature strength behavior of hot-pressed Si₃N₄: evidence for subcritical crack growth. J. Am. Ceram. Soc., 1974, 57(2): 84-87. DOI URL
[90]	RILEY F L. Silicon nitride and related materials. J. Am. Ceram. Soc., 2000, 83(2): 245-265. DOI URL