Pub Date : 1988-09-01DOI: 10.1111/J.1551-2916.1988.TB00272.X
K. Sadananda, A. Singh, Iman, M. Osofsky, V. Tourneau, L. E. Richards
In an effort to make dense, consolidated superconductors, the hot isostatic pressing process was applied to the RBa{sub 2}Cu{sub 3}O{sub 7} system, where R is a rare-earth element. The authors have demonstrated the applicability of the hot isostatic pressing process to produce a fine-grained consolidated solid which can be cut into any desired form. The grain refinement that occurred during hot isostatic pressing was related to the fracture of coarse-grained particles during pressurization. Hot isostatic pressing combined with post-annealing increased the superconducting onset temperature to >95 K. Because of the grain refinement and the higher {Tc} achieved, the superconductor material processed by hot isostatic pressing is also expected to have higher current density, J{sub c}, than its sintered counterpart. The hot isostatic pressing process was also used successfully for the system Bi-Sr-Ca-Cu-O to make dense, bulk superconducting material.
{"title":"Effect of hot isostatic pressing on RBa sub 2 Cu sub 3 O sub 7 superconductors","authors":"K. Sadananda, A. Singh, Iman, M. Osofsky, V. Tourneau, L. E. Richards","doi":"10.1111/J.1551-2916.1988.TB00272.X","DOIUrl":"https://doi.org/10.1111/J.1551-2916.1988.TB00272.X","url":null,"abstract":"In an effort to make dense, consolidated superconductors, the hot isostatic pressing process was applied to the RBa{sub 2}Cu{sub 3}O{sub 7} system, where R is a rare-earth element. The authors have demonstrated the applicability of the hot isostatic pressing process to produce a fine-grained consolidated solid which can be cut into any desired form. The grain refinement that occurred during hot isostatic pressing was related to the fracture of coarse-grained particles during pressurization. Hot isostatic pressing combined with post-annealing increased the superconducting onset temperature to >95 K. Because of the grain refinement and the higher {Tc} achieved, the superconductor material processed by hot isostatic pressing is also expected to have higher current density, J{sub c}, than its sintered counterpart. The hot isostatic pressing process was also used successfully for the system Bi-Sr-Ca-Cu-O to make dense, bulk superconducting material.","PeriodicalId":7260,"journal":{"name":"Advanced Ceramic Materials","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1988-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78608381","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1988-09-01DOI: 10.1111/J.1551-2916.1988.TB00258.X
Chude Feng, W. Schulze
Perovskite lead magnesium niobate, PMN, (Pb(Mg{sub 1/3}, Nb{sub 2/3})O{sub 3}) and its homotypes are the relaxor ferroelectrics, but the PMN family has been reported to be quite difficult to synthesize reproducibly using conventional solid-state reaction methods. This paper discusses the preparation of Pb(Sc{sub 1/2}Nb{sub 1/2})O{sub 3} through hydrolysis and coprecipitation methods. The controlled hydrolysis of Nb(OC{sub 2}H{sub 5}){sub 5} dilute solution produced a fine powder. Coprecipitation of a mixed aqueous solution of scandium nitrate Sc(NO{sub 3}){sub 3} and lead nitrate Pb(NO{sub 3}){sub 2} with an excess of (NH{sub 4}){sub 2}CO{sub 3} solution developed a coating layer of Sc{sub 2}(CO{sub 3}){sub 3} and PbCO{sub 3} on the as-hydrolyzed Nb{sub 2}O{sub 5} particle surface. Calcinating the layered particles resulted in a monosized PSN powder.
{"title":"Synthesis and characterization of monosized Pb(Sc sub 1/2 , Nb sub 1/2 )O sub 3 powder","authors":"Chude Feng, W. Schulze","doi":"10.1111/J.1551-2916.1988.TB00258.X","DOIUrl":"https://doi.org/10.1111/J.1551-2916.1988.TB00258.X","url":null,"abstract":"Perovskite lead magnesium niobate, PMN, (Pb(Mg{sub 1/3}, Nb{sub 2/3})O{sub 3}) and its homotypes are the relaxor ferroelectrics, but the PMN family has been reported to be quite difficult to synthesize reproducibly using conventional solid-state reaction methods. This paper discusses the preparation of Pb(Sc{sub 1/2}Nb{sub 1/2})O{sub 3} through hydrolysis and coprecipitation methods. The controlled hydrolysis of Nb(OC{sub 2}H{sub 5}){sub 5} dilute solution produced a fine powder. Coprecipitation of a mixed aqueous solution of scandium nitrate Sc(NO{sub 3}){sub 3} and lead nitrate Pb(NO{sub 3}){sub 2} with an excess of (NH{sub 4}){sub 2}CO{sub 3} solution developed a coating layer of Sc{sub 2}(CO{sub 3}){sub 3} and PbCO{sub 3} on the as-hydrolyzed Nb{sub 2}O{sub 5} particle surface. Calcinating the layered particles resulted in a monosized PSN powder.","PeriodicalId":7260,"journal":{"name":"Advanced Ceramic Materials","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1988-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74988758","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1988-09-01DOI: 10.1111/J.1551-2916.1988.TB00263.X
K. Venkataraman
{"title":"Predicting the Size Distributions of Fine Powders During Comminution","authors":"K. Venkataraman","doi":"10.1111/J.1551-2916.1988.TB00263.X","DOIUrl":"https://doi.org/10.1111/J.1551-2916.1988.TB00263.X","url":null,"abstract":"","PeriodicalId":7260,"journal":{"name":"Advanced Ceramic Materials","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1988-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75205149","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1988-09-01DOI: 10.1111/J.1551-2916.1988.TB00269.X
J. Pepin
Pd, Ag, and their alloys are important components of thick-film compositions used for conductors and multilayer ceramic capacitor (MLC) electrodes. The formation of palladium oxide during firing complicates the processing of these materials. The system Pd-Ag-O was investigated in the temperature range in which PdO forms, and a steady-state phase diagram in the range of 773 to 1,173 K in air was constructed. The effect of palladium oxidation on MLC electrodes is discussed.
{"title":"Subsolidus phase relations in the system Pd-Ag-O and application to multilayer ceramic capacitor electrodes","authors":"J. Pepin","doi":"10.1111/J.1551-2916.1988.TB00269.X","DOIUrl":"https://doi.org/10.1111/J.1551-2916.1988.TB00269.X","url":null,"abstract":"Pd, Ag, and their alloys are important components of thick-film compositions used for conductors and multilayer ceramic capacitor (MLC) electrodes. The formation of palladium oxide during firing complicates the processing of these materials. The system Pd-Ag-O was investigated in the temperature range in which PdO forms, and a steady-state phase diagram in the range of 773 to 1,173 K in air was constructed. The effect of palladium oxidation on MLC electrodes is discussed.","PeriodicalId":7260,"journal":{"name":"Advanced Ceramic Materials","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1988-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76283543","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1988-07-01DOI: 10.1111/J.1551-2916.1988.TB00251.X
T. Hattori, Y. Iwadate, Tomoyoshi Kato
{"title":"Hydrothermal Synthesis of Hydroxyapatite from Calcium Acetate and Triethyl Phosphate","authors":"T. Hattori, Y. Iwadate, Tomoyoshi Kato","doi":"10.1111/J.1551-2916.1988.TB00251.X","DOIUrl":"https://doi.org/10.1111/J.1551-2916.1988.TB00251.X","url":null,"abstract":"","PeriodicalId":7260,"journal":{"name":"Advanced Ceramic Materials","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1988-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79008675","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1988-07-01DOI: 10.1111/J.1551-2916.1988.TB00234.X
J. Singh, K. Goretta, D. Kupperman, J. Routbort, J. F. Rhodes
The fracture toughness (K{sub IC}), strength, and elastic moduli of hot-pressed Si{sub 3}N{sub 4} reinforced with SiC whiskers were measured at room temperature over a range of SiC content from 0 to 20 wt%. The K{sub IC} was determined from cracks produced by Vickers indentation, the elastic moduli were determined by an ultrasonic technique, and the strength was measured by four-point bending. Although K{sub IC} increases from 4 to 7 MN {center dot} m{sup {minus}3/2} with the addition of 20 wt% SiC, the corresponding increase in strength is relatively small, i.e., from 375 to 550 MPa. Scanning electron microscopy reveals that the small increase in strength is partly related to processing-induced critical flaws.
{"title":"Fracture toughness and strength of SiC-whisker-reinforced Si sub 3 N sub 4 composites","authors":"J. Singh, K. Goretta, D. Kupperman, J. Routbort, J. F. Rhodes","doi":"10.1111/J.1551-2916.1988.TB00234.X","DOIUrl":"https://doi.org/10.1111/J.1551-2916.1988.TB00234.X","url":null,"abstract":"The fracture toughness (K{sub IC}), strength, and elastic moduli of hot-pressed Si{sub 3}N{sub 4} reinforced with SiC whiskers were measured at room temperature over a range of SiC content from 0 to 20 wt%. The K{sub IC} was determined from cracks produced by Vickers indentation, the elastic moduli were determined by an ultrasonic technique, and the strength was measured by four-point bending. Although K{sub IC} increases from 4 to 7 MN {center dot} m{sup {minus}3/2} with the addition of 20 wt% SiC, the corresponding increase in strength is relatively small, i.e., from 375 to 550 MPa. Scanning electron microscopy reveals that the small increase in strength is partly related to processing-induced critical flaws.","PeriodicalId":7260,"journal":{"name":"Advanced Ceramic Materials","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1988-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81285111","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1988-07-01DOI: 10.1111/J.1551-2916.1988.TB00224.X
L. Sheppard
The ceramic fever of the early 1980s has abated somewhat and the enthusiasm held by many has been replaced by a more cautious approach. Perhaps this is no more evident than with those involved with the ceramic engine. Consequently, Argonne National Laboratory was asked by the Department of Energy to update their economic study made in the early 1980s, which had revealed that the use of advanced ceramics in automobiles and other vehicles could substantially increase US economic growth. The new study was refined so that both government and industry could make better decisions on developing ceramic engine technology based on accurate projections of market development and timing. In addition, a panel discussion was held during the 1988 SAE International congress and Exposition to discuss the results of the survey and provide an open forum for additional comments, some of which are presented in this paper.
{"title":"Global outlook for the ceramic heat engine","authors":"L. Sheppard","doi":"10.1111/J.1551-2916.1988.TB00224.X","DOIUrl":"https://doi.org/10.1111/J.1551-2916.1988.TB00224.X","url":null,"abstract":"The ceramic fever of the early 1980s has abated somewhat and the enthusiasm held by many has been replaced by a more cautious approach. Perhaps this is no more evident than with those involved with the ceramic engine. Consequently, Argonne National Laboratory was asked by the Department of Energy to update their economic study made in the early 1980s, which had revealed that the use of advanced ceramics in automobiles and other vehicles could substantially increase US economic growth. The new study was refined so that both government and industry could make better decisions on developing ceramic engine technology based on accurate projections of market development and timing. In addition, a panel discussion was held during the 1988 SAE International congress and Exposition to discuss the results of the survey and provide an open forum for additional comments, some of which are presented in this paper.","PeriodicalId":7260,"journal":{"name":"Advanced Ceramic Materials","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1988-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88949590","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1988-07-01DOI: 10.1111/J.1551-2916.1988.TB00241.X
M. Rahaman, L. Jonghe, M. Chu
Powder compacts having a nominal composition of YBa{sub 2}Cu{sub 3}O{sub 6+{delta}} were sintered in air between 910{degree} to 940{degree}C in a loading dilatometer that permitted the application of small, controlled uniaxial stresses to the sintering compact. The highest density (95% of theoretical) was obtained after sintering without load for {approx} 2 h at 935{degree}C. The application of constant, small uniaxial stresses produced extensive shear deformation and a small increase in the densification rate. The measured ratio of the densification rate to the creep rate provided strong support for the presence of a liquid phase during sintering. The data allowed the measurement of the ratio of the creep viscosity to the densification viscosity, which was {approx} 0.8 over the density range 0.6 to 0.8, and the sintering stress, which was {approx} 0.8 over the density range 0.6 to 0.8, and the sintering stress, which was {approx} 400 kPa. These data show that extensive shear deformation and small but measurable increases in the densification rates may be achieved by the application of relatively small uniaxial stresses ({approx} 1 MPa) during sintering of YBa{sub 2}Cu{sub 3}O{sub 6+{delta}} powder compacts.
{"title":"Densification and Shear Deformation in YBa 2 Cu 3 O 6+δ Powder Compacts","authors":"M. Rahaman, L. Jonghe, M. Chu","doi":"10.1111/J.1551-2916.1988.TB00241.X","DOIUrl":"https://doi.org/10.1111/J.1551-2916.1988.TB00241.X","url":null,"abstract":"Powder compacts having a nominal composition of YBa{sub 2}Cu{sub 3}O{sub 6+{delta}} were sintered in air between 910{degree} to 940{degree}C in a loading dilatometer that permitted the application of small, controlled uniaxial stresses to the sintering compact. The highest density (95% of theoretical) was obtained after sintering without load for {approx} 2 h at 935{degree}C. The application of constant, small uniaxial stresses produced extensive shear deformation and a small increase in the densification rate. The measured ratio of the densification rate to the creep rate provided strong support for the presence of a liquid phase during sintering. The data allowed the measurement of the ratio of the creep viscosity to the densification viscosity, which was {approx} 0.8 over the density range 0.6 to 0.8, and the sintering stress, which was {approx} 0.8 over the density range 0.6 to 0.8, and the sintering stress, which was {approx} 400 kPa. These data show that extensive shear deformation and small but measurable increases in the densification rates may be achieved by the application of relatively small uniaxial stresses ({approx} 1 MPa) during sintering of YBa{sub 2}Cu{sub 3}O{sub 6+{delta}} powder compacts.","PeriodicalId":7260,"journal":{"name":"Advanced Ceramic Materials","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1988-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83314506","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1988-07-01DOI: 10.1111/J.1551-2916.1988.TB00243.X
L. Pejryd
Using glass-encapsulated hot isostatic pressing, additive-free Si{sub 3}N{sub 4} and Si{sub 3}N{sub 4} containing a 50/50 mol% mixture of CaO and MgO up to 6 wt% were sintered from 1,550{degree} to 1,750{degree}C at 160 MPa. Samples containing oxide additions achieved full density, whereas additive-free samples did not reach full density. In fully densified samples, the Vickers hardness decreased with increasing oxide content and sintering temperature. At 1,000{degree}C the oxide content, and, to a small extent, the sintering temperature, determine hardness. Fracture toughness increases with increasing oxide content and increasing sintering temperature. However, transformation of {alpha}-Si{sub 3}N{sub 4} to {beta}-Si{sub 3}N{sub 4} is enhanced by the temperature, but the oxide content has no significant effect.
{"title":"Microstructure and mechanical properties of CaO/MgO-doped Si sub 3 N sub 4 sintered by hot isostatic pressing","authors":"L. Pejryd","doi":"10.1111/J.1551-2916.1988.TB00243.X","DOIUrl":"https://doi.org/10.1111/J.1551-2916.1988.TB00243.X","url":null,"abstract":"Using glass-encapsulated hot isostatic pressing, additive-free Si{sub 3}N{sub 4} and Si{sub 3}N{sub 4} containing a 50/50 mol% mixture of CaO and MgO up to 6 wt% were sintered from 1,550{degree} to 1,750{degree}C at 160 MPa. Samples containing oxide additions achieved full density, whereas additive-free samples did not reach full density. In fully densified samples, the Vickers hardness decreased with increasing oxide content and sintering temperature. At 1,000{degree}C the oxide content, and, to a small extent, the sintering temperature, determine hardness. Fracture toughness increases with increasing oxide content and increasing sintering temperature. However, transformation of {alpha}-Si{sub 3}N{sub 4} to {beta}-Si{sub 3}N{sub 4} is enhanced by the temperature, but the oxide content has no significant effect.","PeriodicalId":7260,"journal":{"name":"Advanced Ceramic Materials","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1988-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79554545","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1988-07-01DOI: 10.1111/J.1551-2916.1988.TB00248.X
L. Silverman
A synthetic route is described for making carbothermally reduced powders from colloidal oxide precursors trapped in a polymer matrix. The entrapping resin, which is formed by polymerization of a monomer dissolved in the colloid, serves both to minimize particle agglomeration during reaction and as the source of carbon for reduction. Following reduction, the remaining carbon matrix is removed by oxidation. This strategy was used to synthesize aluminum nitride powder via trapping of colloidal alumina in poly(furfuryl alcohol) resin.
{"title":"Carbothermal synthesis of aluminum nitride","authors":"L. Silverman","doi":"10.1111/J.1551-2916.1988.TB00248.X","DOIUrl":"https://doi.org/10.1111/J.1551-2916.1988.TB00248.X","url":null,"abstract":"A synthetic route is described for making carbothermally reduced powders from colloidal oxide precursors trapped in a polymer matrix. The entrapping resin, which is formed by polymerization of a monomer dissolved in the colloid, serves both to minimize particle agglomeration during reaction and as the source of carbon for reduction. Following reduction, the remaining carbon matrix is removed by oxidation. This strategy was used to synthesize aluminum nitride powder via trapping of colloidal alumina in poly(furfuryl alcohol) resin.","PeriodicalId":7260,"journal":{"name":"Advanced Ceramic Materials","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1988-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74762248","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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