Development of non-shrinkable ceramic composites for use in high-power microwave tubes
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摘要
Al_2O_3–CaO–SiC-based ceramic composites with four different compositions were sintered at 1700℃ for 3 h in an air furnace. The phase analysis, microstructural characterization, and elemental composition determination of the developed composites were performed by X-ray diffraction(XRD), field-emission scanning electron microscopy(FESEM), and energy-dispersive X-ray(EDAX) analysis, respectively. The shrinkage, thermal properties, and electrical resistivity of the composites were also studied. The experimental results showed the effects of adding silicon carbide and calcia to alumina on the thermal, electrical, and shrinkage properties of the resultant composites. Among the four investigated ceramic composites, the one composed of 99 wt% alumina, 0.5 wt% CaO, and 0.5 wt% SiC exhibited the best characteristics for use as a potting material in a dispenser cathode of a microwave tube. The material exhibited slight expansion instead of shrinkage during drying or firing. Other properties of the composite powder, such as its thermal properties and electrical resistivity, were comparable to those of a commercial alumina powder.
Al_2O_3–CaO–SiC-based ceramic composites with four different compositions were sintered at 1700℃ for 3 h in an air furnace. The phase analysis, microstructural characterization, and elemental composition determination of the developed composites were performed by X-ray diffraction(XRD), field-emission scanning electron microscopy(FESEM), and energy-dispersive X-ray(EDAX) analysis, respectively. The shrinkage, thermal properties, and electrical resistivity of the composites were also studied. The experimental results showed the effects of adding silicon carbide and calcia to alumina on the thermal, electrical, and shrinkage properties of the resultant composites. Among the four investigated ceramic composites, the one composed of 99 wt% alumina, 0.5 wt% CaO, and 0.5 wt% SiC exhibited the best characteristics for use as a potting material in a dispenser cathode of a microwave tube. The material exhibited slight expansion instead of shrinkage during drying or firing. Other properties of the composite powder, such as its thermal properties and electrical resistivity, were comparable to those of a commercial alumina powder.
Al_2O_3–CaO–SiC-based ceramic composites with four different compositions were sintered at 1700℃ for 3 h in an air furnace. The phase analysis, microstructural characterization, and elemental composition determination of the developed composites were performed by X-ray diffraction(XRD), field-emission scanning electron microscopy(FESEM), and energy-dispersive X-ray(EDAX) analysis, respectively. The shrinkage, thermal properties, and electrical resistivity of the composites were also studied. The experimental results showed the effects of adding silicon carbide and calcia to alumina on the thermal, electrical, and shrinkage properties of the resultant composites. Among the four investigated ceramic composites, the one composed of 99 wt% alumina, 0.5 wt% CaO, and 0.5 wt% SiC exhibited the best characteristics for use as a potting material in a dispenser cathode of a microwave tube. The material exhibited slight expansion instead of shrinkage during drying or firing. Other properties of the composite powder, such as its thermal properties and electrical resistivity, were comparable to those of a commercial alumina powder.
引文
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[15]O.S.S.Lamba,S.C.Nangru,L.M.Joshi,A.Sharma,V.P.Singh,and N.C.Gupta,Choice of alumina ceramics for 5MW pulsed power klystron,Indian J.Eng.Mater.S.,7(2000),No.5,p.443.
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[19]P.Swartzentruber,M.Collier,R.De Wees,W.Epperson,CPoole,B.Rupp,D.Bowling,E.Fadde,A.Floyd,P.Rottmann,R.Wilson,T.J.Balk,S.Roberts,J.Tarter,and M.Effgen,Alternative ceramic potting materials for dispenser cathodes,[in]International Vacuum Electronics Conference(IVEC),2012,IEEE International,Monterey,CA,USA,p.483.
[20]A.Kisko,J.Talonen,D.A.Porter,and L.P.Karjalainen,Effect of Nb microalloying on reversion and grain growth in a high-Mn 204Cu austenitic stainless steel,ISIJ Int.,55(2015),No.10,p.2217.
[21]S.Miao,Z.M.Xie,L.F.Zeng,T.Zhang,X.P.Wang,Q.F.Fang,and C.S.Liu,Mechanical properties,thermal stability and microstructure of fine-grained W-0.5wt%Ta C alloys fabricated by an optimized multi-step process,Nucl.Mater.Energy,13(2017),p.12.
[22]G.E.Jr.,Oxidation behavior of silicon carbide,J.Am.Ceram.Soc.,41(1958),No.9,p.347.
[23]L.U.J.T.Ogbuji and M.Singh,High-temperature oxidation behavior of reaction-formed silicon carbide ceramics,J.Mater.Res.,10(1995),No.12,p.3232.
[24]A.Theerapapvisetpong,S.Jiemsirilers,P.Thavorniti,and R.Conradt,Barium-free glass-ceramic sealants from the system Ca O-Mg O-B2O3-Al2O3-Si O2 for application in the SOFC,Mater.Sci.Forum,695(2011),p.1.
[2]R.B.True,M.F.Kirshner,L.Turek,G.R.Good,R.J.Hanse,T.M.Bemis,and R.J.Bartkowski,Dispenser cathode high power gridded klystron gun,[in]International Vacuum Electronics Conference(IVEC),IEEE International,USA,2004,p.328.
[3]T.J.Grant and L.R.Falce,Impact of dispenser cathode thickness on useful operating life,[in]International Vacuum Electronics Conference(IVEC),IEEE International,USA,2004,p.305.
[4]V.B.Shields,Applications of silicon carbide for high temperature electronics and sensors,NASA Jet Propulsion Laboratory,Tech Briefs,20(1996),p.55.
[5]P.Swartzentruber,M.Collier,R.Dewees,W.Epperson,C.Poole,B.Rupp,D.Bowling,E.Fadde,A.Floyd,P.Rottmann,R.Wilson,T.J.Balk,S.Roberts,J.Tarter,and M.Effgen,Alternative ceramic potting materials for dispenser cathodes,[in]International Vacuum Electronics Conference(IVEC),IEEEInternational,USA,2012,p.483.
[6]R.K.Barik,A.Bera,R.S.Raju,A.K.Tanwar,I.K.Baek,S.H.Min,O.J.Kwon,M.A.Sattorov,K.W.Lee,and G.S.Park,Development of alloy-film coated dispenser cathode for terahertz vacuum electron devices application,Appl.Surf.Sci.,276(2013),p.817.
[7]R.Bhattacharya,H.Khatun,N.K.Singh,U.Singh,and A.K.Sinha,Design of cathode heater assembly for high power gyrotron,Frequenz,67(2013),No.5-6,p.163.
[8]D.Pedrini,T.Misuri,F.Paganucci,and M.Andrenucci,Development of hollow cathodes for space electric propulsion at Sitael,Aerospace,4(2017),No.2,p.26.
[9]L.Ives,G.Miram,M.Read,M.Mizuhara,P.Borchard,L.Falce,and K.Gunther,Development of improved cathodes for high power RF sources,[in]Proceedings of the Particle Accelerator Conference,IEEE International,USA,2003,p.1113.
[10]C.D.Marchewka,Non-Uniform Emission Studies of a Magnetron Injection Gun[Dissertation],Massachusetts Institute of Technology(MIT),USA,2006,p.1.
[11]A.S.Gilmour,Jr.,Microwave Tubes,Artech House,Boston,1986,p.733.
[12]D.F.Simmons,C.M.Fortgang,and D.B.Holtkamp,Using multispectral imaging to measure temperature profiles and emissivity of large thermionic dispenser cathodes,Rev.Sci.Instrum.,76(2005),No.4,art.No.044901.
[13]D.J.Kaczynski and K.A.Walsh,Beryllium Oxide,[in]Conference of Raw Materials for Advanced and Engineered Ceramics,6(1985),No.9-10,p.1261.
[14]T.V.Thamaraiselvi and S.S.Rajeswari,Biological evaluation of bioceramic materials-A review trends,Trends Biomater.Artif.Organs,18(2004),No.1,p.9.
[15]O.S.S.Lamba,S.C.Nangru,L.M.Joshi,A.Sharma,V.P.Singh,and N.C.Gupta,Choice of alumina ceramics for 5MW pulsed power klystron,Indian J.Eng.Mater.S.,7(2000),No.5,p.443.
[16]S.Roberts,Sources of temperature variance in dispenser cathodes,[in]International Vacuum Electronics Conference(IVEC),IEEE International,USA,2004,p.299.
[17]C.W.Park and D.Y.Yoon,Effects of Si O2,Ca O2,and Mg Oadditions on the grain growth of alumina,J.Am.Ceram.Soc.,83(2000),No.10,p.2605.
[18]K.S.Pal,S.Ghosh,N.Dandapat,S.Datta,D.Basu,and R.S.Raju,Development of suitable potting material for dispenser cathodes of a high power microwave tube,Mater.Sci.Eng.B,177(2012),No.2,p.228.
[19]P.Swartzentruber,M.Collier,R.De Wees,W.Epperson,CPoole,B.Rupp,D.Bowling,E.Fadde,A.Floyd,P.Rottmann,R.Wilson,T.J.Balk,S.Roberts,J.Tarter,and M.Effgen,Alternative ceramic potting materials for dispenser cathodes,[in]International Vacuum Electronics Conference(IVEC),2012,IEEE International,Monterey,CA,USA,p.483.
[20]A.Kisko,J.Talonen,D.A.Porter,and L.P.Karjalainen,Effect of Nb microalloying on reversion and grain growth in a high-Mn 204Cu austenitic stainless steel,ISIJ Int.,55(2015),No.10,p.2217.
[21]S.Miao,Z.M.Xie,L.F.Zeng,T.Zhang,X.P.Wang,Q.F.Fang,and C.S.Liu,Mechanical properties,thermal stability and microstructure of fine-grained W-0.5wt%Ta C alloys fabricated by an optimized multi-step process,Nucl.Mater.Energy,13(2017),p.12.
[22]G.E.Jr.,Oxidation behavior of silicon carbide,J.Am.Ceram.Soc.,41(1958),No.9,p.347.
[23]L.U.J.T.Ogbuji and M.Singh,High-temperature oxidation behavior of reaction-formed silicon carbide ceramics,J.Mater.Res.,10(1995),No.12,p.3232.
[24]A.Theerapapvisetpong,S.Jiemsirilers,P.Thavorniti,and R.Conradt,Barium-free glass-ceramic sealants from the system Ca O-Mg O-B2O3-Al2O3-Si O2 for application in the SOFC,Mater.Sci.Forum,695(2011),p.1.