不同晶粒尺寸LiTaO_3韧化Al_2O_3陶瓷的微观结构和性能研究
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摘要
针对Al_2O_3陶瓷的韧化,本论文把不同晶粒大小的LiTaO_3粉体作为第二相引入到Al_2O_3结构陶瓷,研究了LiTaO_3晶粒大小对LiTaO_3/Al_2O_3复相陶瓷(简称LTA)微观结构和力学性能的影响,探讨了LiTaO_3/Al_2O_3复相陶瓷中LiTaO_3晶粒内电畴结构的形成机理和复相陶瓷的韧化机理。研究工作对发展陶瓷材料的组织结构设计和陶瓷材料韧化技术具有重要的科学意义。
采用溶胶-凝胶法,以Ta_2O_5和Li_2CO_3为原料,以柠檬酸(CA)为络合剂,乙二醇为酯化剂,聚乙二醇(PEG)为分散剂制备前躯体,分别在650℃、750℃、800℃、850℃、900℃温度下煅烧制备了平均粒径为91nm、125nm、310nm、324nm、386nm的LiTaO_3粉体。
通过热压烧结,在1350℃保温90min条件下制备了含有不同晶粒尺寸LiTaO_3的Al_2O_3复相陶瓷,致密度均在96%以上。研究得到随着第二相LiTaO_3晶粒尺寸的减小LiTaO_3/Al_2O_3复相陶瓷的力学性能有所提高。添加15vol%的平均粒径为91nmLiTaO_3的LTA复相陶瓷的平均抗弯强度和平均断裂韧性分别达到511MPa和6.13MPa·m~(1/2)。LiTaO_3晶粒尺寸在100nm左右时其力学性能递减趋势较为明显,呈现较典型的“第二相颗粒尺寸阈值效应”。
研究发现LiTaO_3/Al_2O_3复相陶瓷中LiTaO_3晶粒内的电畴结构特征为“尖劈状”、“板条状”和“薄片状”的90°电畴,阐明90°电畴的形成机制为“应力诱发机制”。研究揭示LiTaO_3第二相对LiTaO_3/Al_2O_3复相陶瓷的韧化机理为“裂纹偏转”和“电畴翻转能量消耗”的协同作用机制。
For toughening Al_2O_3 ceramics,the paper introduced LiTaO_3 powders of different grain sizes into Al_2O_3 structural ceramics as the second phase,investigate the influence of the LiTaO_3 grain size on the microstructure and mechanical properties of LiTaO_3/Al_2O_3 composite ceramics(the LTA),explore formation mechanism of domain structures in the LiTaO_3 grain also,research work has important scientific significance for development of ceramic materials structure design and Toughening technology.
Research shows LiTaO_3 powders with 91nm,125nm,310nm,324nm,386nm grain sizes are synthesized by sol-gel precursor calcined at 650℃,750℃,800℃,850℃, 900℃for 2h,the precursor prepared,using Ta_2O_5 and Li_2CO_3 as raw materials,citric acid(CA) as chelating agent,ethylene glycol(EG)as esterification agent and polyethylene glycol(PEG) as dispersant agent by the sol-gel technique.
Al_2O_3 ceramics with LiTaO_3 of different grain sizes prepared at 1350℃for 90min by hot-pressed sintering,the relative density is above 96%.Study shows that with decrease initial grain size of LiTaO_3,the flexural strength and fracture strength increased, when 15vol%LiTaO_3 powders of 91nm introduced Al_2O_3 ceramics,the LTA composite ceramics' flexural strength and fracture strength values reached 511MPa and 6.13MPa·m~(1/2) respectively.When LiTaO_3 grain size is about 100nm decreasing trend of the mechanical properties is Obvious,showing typical "threshold effect of second phase particle size".
Research found the domain structure Characteristics are "wedge-shaped","banded", "Lamellar" 90°domain in the LiTaO_3 grains of LTA composite ceramics,clarify the formation mechanism 90°ferroelectric domain is the "stress-induced mechanism".The study reveals the second phase of LiTaO_3 toughening mechanisms are "crack deflection" and "energy consumption toughening of domain switching" synergy mechanism in LiTaO_3/Al_2O_3 composite ceramics.
采用溶胶-凝胶法,以Ta_2O_5和Li_2CO_3为原料,以柠檬酸(CA)为络合剂,乙二醇为酯化剂,聚乙二醇(PEG)为分散剂制备前躯体,分别在650℃、750℃、800℃、850℃、900℃温度下煅烧制备了平均粒径为91nm、125nm、310nm、324nm、386nm的LiTaO_3粉体。
通过热压烧结,在1350℃保温90min条件下制备了含有不同晶粒尺寸LiTaO_3的Al_2O_3复相陶瓷,致密度均在96%以上。研究得到随着第二相LiTaO_3晶粒尺寸的减小LiTaO_3/Al_2O_3复相陶瓷的力学性能有所提高。添加15vol%的平均粒径为91nmLiTaO_3的LTA复相陶瓷的平均抗弯强度和平均断裂韧性分别达到511MPa和6.13MPa·m~(1/2)。LiTaO_3晶粒尺寸在100nm左右时其力学性能递减趋势较为明显,呈现较典型的“第二相颗粒尺寸阈值效应”。
研究发现LiTaO_3/Al_2O_3复相陶瓷中LiTaO_3晶粒内的电畴结构特征为“尖劈状”、“板条状”和“薄片状”的90°电畴,阐明90°电畴的形成机制为“应力诱发机制”。研究揭示LiTaO_3第二相对LiTaO_3/Al_2O_3复相陶瓷的韧化机理为“裂纹偏转”和“电畴翻转能量消耗”的协同作用机制。
For toughening Al_2O_3 ceramics,the paper introduced LiTaO_3 powders of different grain sizes into Al_2O_3 structural ceramics as the second phase,investigate the influence of the LiTaO_3 grain size on the microstructure and mechanical properties of LiTaO_3/Al_2O_3 composite ceramics(the LTA),explore formation mechanism of domain structures in the LiTaO_3 grain also,research work has important scientific significance for development of ceramic materials structure design and Toughening technology.
Research shows LiTaO_3 powders with 91nm,125nm,310nm,324nm,386nm grain sizes are synthesized by sol-gel precursor calcined at 650℃,750℃,800℃,850℃, 900℃for 2h,the precursor prepared,using Ta_2O_5 and Li_2CO_3 as raw materials,citric acid(CA) as chelating agent,ethylene glycol(EG)as esterification agent and polyethylene glycol(PEG) as dispersant agent by the sol-gel technique.
Al_2O_3 ceramics with LiTaO_3 of different grain sizes prepared at 1350℃for 90min by hot-pressed sintering,the relative density is above 96%.Study shows that with decrease initial grain size of LiTaO_3,the flexural strength and fracture strength increased, when 15vol%LiTaO_3 powders of 91nm introduced Al_2O_3 ceramics,the LTA composite ceramics' flexural strength and fracture strength values reached 511MPa and 6.13MPa·m~(1/2) respectively.When LiTaO_3 grain size is about 100nm decreasing trend of the mechanical properties is Obvious,showing typical "threshold effect of second phase particle size".
Research found the domain structure Characteristics are "wedge-shaped","banded", "Lamellar" 90°domain in the LiTaO_3 grains of LTA composite ceramics,clarify the formation mechanism 90°ferroelectric domain is the "stress-induced mechanism".The study reveals the second phase of LiTaO_3 toughening mechanisms are "crack deflection" and "energy consumption toughening of domain switching" synergy mechanism in LiTaO_3/Al_2O_3 composite ceramics.
引文
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[27]Heuer A.H.Transformation toughness in ZrO_2-containins ceramic[J].J Am Ceram Soc,1987,70(10):689-698.
[28]X.M.Chen,B.Yang,Mater.Lett.33(1997) 237
[29]Yangai Liu,Yu Zhou,Deehang Jia.Domain structures andtoughening mechanism in Al_2O_3matrixceramic composites dispersed with piezoelectric LiTaO_3[J].Materials Science and Engineering.A347(2003) 359-364
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[33]R.L(u丨¨)thi,H.Haefke,K.P.Meyer,E.Mayer,L.Howald,H.J.G(u丨¨)ntherodt.Surface and Domain Structures of Ferroelectric Crystals Studied with Scanning Force Microscopy[J].Appl.Phys.1993,74(12):7461-7471
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[37]S.C.Navale a,A.B.Gaikwad b,V.Ravi a.A coprecipitation technique to prepare LiTaO_3powders[J].Materials Letters 60(2006) 1047-1048
[38]赵九蓬,权茂华,李壵.聚合物前驱体方法低温合成LiTaO_3纳米粉体[J].无机化学学报.2008.11,Vol.24 No.11 1869-1873
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[2]KonopKaK,Ozieblo A.Microstructure and the fracture toughness of the Al_2O_3-Fe composites[J].Materials Charaeterization,2001,9(46):125-129
[3]Pernilla Pettersson,Mats Johnsson.Thermal shock properties of alumina reinforced with Ti(C,N)whiskers.[J].J Eur Ceram Soc,2003,2(23):309-313
[4]Heuer A.H.Transformation toughness in ZrO_2-containins ceramic[J].J Am Ceram Soc,1987,70(10):689-698.
[5]X.M.Chen,B.Yang.A new approach for toughening of ceramics[J].Mater.Lett.33(1997) 237
[6]Yangai Liu,Yu Zhou,Dechang Jia.Domain structures andtoughening mechanism in Al_2O_3matrixceramic composites dispersed with piezoelectric LiTaO_3.Materials Science and Engineering[J].A347(2003) 359-364
[7]Y.Zhou,Q.L.Ge,T.C.Lei,T.Sakuma.Mirostructure and Mechanical Properties of ZrO_2-2mol%Y_2O_3 Ceramics[J].Ceramics International.1990,16(6):349-354
[8]K.T.Faber.Mcrocracking Contributions to the Toughness of ZrO_2-Based Ceramics.Advances in Ceramics Science and Technology of Zirconia Ⅱ.Proceedings of the Second International Conference,Am[J].Ceram.Soc.,OH,1984,12:293-305
[9]P.S.Nicholson,T.B.Troczynsld.The Resistance to Fracture of PSZ and PSZ-Na-Beta-Al_2O_3Composites at 1300℃[J].American Ceramic Society Bulletin.1986,65:772-775
[10]K.T.Faber,A.G.Evans.Crack Defection Processes-1[J].Theory.Acta Metall.1983,31(4):565-576
[11]N.Claussen.The Combination of Zirconia Toughening With Whisker Reinforcement[J].The Ceramic Society of Japan.1986:140-141
[12]P.F.Becher.Microstructural Design of Toughened Ceramics[J].J.Am.Ceram.Soc.1991,74(2):255-269
[13]P.F.Becher,E.R.Fuller,P.Angelini.Matrix-Grain-Bridging Contributions to the Toughness of Whisker-Reinforced Ceramics[J].J.Am.Ceram.Soc.1991,74(9):2131-2137
[14]葛启录.Al_2O_3-ZrO_2陶瓷材料的显微结构和力学性能.哈尔滨工业大学博士学位论文.1992
[15]D.B.Marshall,W.L.Morris,B.N.Cox,M.S.Dadkhah.Toughening Mechanisms in Cemented Carbides[J].Am.Ceram.Soc.1990,73(10):2938-2943
[16]G.C.Wei,P.F.Becher.Improvements in Mechanical Properties in SiC by the Addition of TiC Particles[J].Am.Ceram.Soc.1984,67(8):571-574
[17]M.Taya,S.Hovashi,A.S.Kobayashi,H.S.Yoon.Toughening of a Particulate-Reinforced Ceramic-Matrix Composite by Thermal Residual Stress[J].Am.Ceram.Soc.1990,73(5):1382-1391
[18]X.M.Chen,B.Yang.A New Approach for Toughening of Ceramics[J].Mater.Lett.1997,33:237-240
[19]T.Kosmac,M.Drofenik,B.Malie,S.Besenicar,M.Kosec,V.Krasevec.The Influence of Dispersed ZrO_2 Particles on the Properties of Some Electronic Ceramics[J].In:S.Somiga,ed.Advanced Ceramics Ⅱ.1988:29-44
[20]B.Malic,M.Kosec,T.Kosmac.Mechanical and Electric Properties of PZT-ZrO_2Composites.Ferroelectrics[J].1992,129:147-155
[21]T.Yamamoto,H.Igarashi,K.Okazaki.Electrical and Mechanical Properties of SiC Whisker Reinforced PZT[J].Ceramics.Ferroelectrics.1985,63:281-288
[22]J.S.Yang,X.M.Chen,T.Aizawa,M.Kuwabara.PZT Based Piezoelectric Ceramics with Enhanced Fracture Toughness[J].Solid State Ionics.1998,108:117-121
[23]杨为佑,谢志鹏,苗赫灌.异向生长晶粒增韧Al_2O_3陶瓷的研究进展[J].无机材料学报,2003,18(5):962
[24]Bae I,Baik S.Abnormal growth of alumina[J].J Am Ceram Soc,1997,80(5):1149-1156
[25]KonopKaK,Ozieblo A.Microstructure and the fracture toughness of the Al_2O_3- Fe composites[J].Materials Charaeterizatien,2001,9(46):125-129
[26]Pemilla Pettersson,Mats Jobnsson.Thermal shock properties of alumina reinforced with Ti(C,N)whiskers.[J].J Eur Ceram Soe,2003,2(23):309-313
[27]Heuer A.H.Transformation toughness in ZrO_2-containins ceramic[J].J Am Ceram Soc,1987,70(10):689-698.
[28]X.M.Chen,B.Yang,Mater.Lett.33(1997) 237
[29]Yangai Liu,Yu Zhou,Deehang Jia.Domain structures andtoughening mechanism in Al_2O_3matrixceramic composites dispersed with piezoelectric LiTaO_3[J].Materials Science and Engineering.A347(2003) 359-364
[30]张福学,孙慷.压电学(下册)[M].国防工业出版社,1984
[31]钟维烈.铁电体物理学[M].科学出版社,1998
[32]G.Y.Robinson,R.M.White.Scanning Electron Microscopy of Ferroelectric Domains in Barium Titanate[J].Appl.Phys.Lett.1967,10:320-323
[33]R.L(u丨¨)thi,H.Haefke,K.P.Meyer,E.Mayer,L.Howald,H.J.G(u丨¨)ntherodt.Surface and Domain Structures of Ferroelectric Crystals Studied with Scanning Force Microscopy[J].Appl.Phys.1993,74(12):7461-7471
[34]刘希,周和平,张孝文,韩立,陈皓明.扫描探针显微镜研究弛豫铁电体电畴生长[J].无机 材料学报.1999,14(6):1000-1004
[35]V.V.Shakmanov,G.V.Spivak.A Mierodiffraction Investigation of the Domain Structure ha Barium Titanate Films[J].Sov.Phs.-Solid State(Engl.Transl.).1968,10:802-806
[36]D.B.Williams.Practical Analytical Electron Microscopy in Materials Science[J].Philips Electron Optics Publishing,Mahwah,NJ,1984:126
[37]S.C.Navale a,A.B.Gaikwad b,V.Ravi a.A coprecipitation technique to prepare LiTaO_3powders[J].Materials Letters 60(2006) 1047-1048
[38]赵九蓬,权茂华,李壵.聚合物前驱体方法低温合成LiTaO_3纳米粉体[J].无机化学学报.2008.11,Vol.24 No.11 1869-1873
[39]袁颖.功能陶瓷超微细粉体的制备及应用研究.博士论文.电子科技大学.2005.03
[40]G.Evans.Perspective on the Development of High-Toughness Ceramics[J].Am.Ceram.Soc.1990,73(2):187-206
[41]M.Yasuoka,K.Hirao,M.E.Brito,S.Kanzaki.High-Strength and High-Toughness Ceramics in the Al_2O_3/LaA_(11)O_8 Systems[J].Am.Ceram.Soc.1995,78(7):1853-56
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