It is well known, that ceramics having a wide scale of porous morphologies are used in many different applications such as bio-ceramics, chemical engineering, exhaust gas treatment, fi ltration etc. [1, 2]. Porous systems ranging from an entirely open pore network e.g. for catalyst supports to entirely closed pore structures e.g. for insulation materials exist. The application of such porous ceramic systems is quite often connected to specifi c transport properties, e.g. fl ow of media in fi ltration, ion conductivity in electrochemical membranes or thermal conductivity in insulation materials. All these transport properties are known for bulk and dense materials but in case of biphasic materials (bulk and pores) such properties could be calculated only if the geometry of the biphasic material is known in detail. On the other hand, ceramic engineering methods provide different routes to tailor porosity and microstructure to a certain degree. Typical methods to produce and to adjust porosity are partial sintering, use of pore formers or templates, foaming, freezing or size exclusion of particles. Typical development schemes involve preparation of sets of samples and measurement of the resulting properties. By optimisation strategies, sometimes supported by “design of experiment” methodologies, the target properties can be reached. By employing a strategy of model generation and virtual material testing this process might be signifi cantly optimised. Fig. 1 shows a general scheme of development cycles, which involve different stages of Characterization and Modelling of Structure and Transport Properties of Porous Ceramics
{"title":"Characterization and modelling of structure and transport properties of porous ceramics","authors":"D. Penner, L. Holzer","doi":"10.21256/ZHAW-3574","DOIUrl":"https://doi.org/10.21256/ZHAW-3574","url":null,"abstract":"It is well known, that ceramics having a wide scale of porous morphologies are used in many different applications such as bio-ceramics, chemical engineering, exhaust gas treatment, fi ltration etc. [1, 2]. Porous systems ranging from an entirely open pore network e.g. for catalyst supports to entirely closed pore structures e.g. for insulation materials exist. The application of such porous ceramic systems is quite often connected to specifi c transport properties, e.g. fl ow of media in fi ltration, ion conductivity in electrochemical membranes or thermal conductivity in insulation materials. All these transport properties are known for bulk and dense materials but in case of biphasic materials (bulk and pores) such properties could be calculated only if the geometry of the biphasic material is known in detail. On the other hand, ceramic engineering methods provide different routes to tailor porosity and microstructure to a certain degree. Typical methods to produce and to adjust porosity are partial sintering, use of pore formers or templates, foaming, freezing or size exclusion of particles. Typical development schemes involve preparation of sets of samples and measurement of the resulting properties. By optimisation strategies, sometimes supported by “design of experiment” methodologies, the target properties can be reached. By employing a strategy of model generation and virtual material testing this process might be signifi cantly optimised. Fig. 1 shows a general scheme of development cycles, which involve different stages of Characterization and Modelling of Structure and Transport Properties of Porous Ceramics","PeriodicalId":9707,"journal":{"name":"Cfi-ceramic Forum International","volume":"27 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77949088","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 : 2007-12-29DOI: 10.1002/9783527612765.CH77
G. Link, S. Rhee, L. Feher, M. Thumm
At the Forschungszentrum Karlsruhe (D), a compact gyrotron system was installed in 1994 to investigate technological application in the field of high temperature materials processing using millimeter waves (mm-waves). Besides the improvement of the system design, research activities are mainly engaged in studies on debindering and sintering of various types of advanced structural and functional ceramics. Due to volumetric heating and enhanced sintering kinetics, the application of microwaves allows a shortening of the processing time, thereby reducing energy consumption. In addition, microwave technology gives the unique possibility of influencing the microstructure and physical properties of the ceramic materials. This article will give an overview of the benefits of the mm-wave technology with respect to the sintering of structural ceramics, such as Al 2 O 3 , Si 3 N 4 , or TiO 2 -ZrO 2 -MgO multicomponent ceramics, nanocrystalline oxide ceramics, as well as PZT piezoceramics as one of the most interesting classes of functional ceramics.
卡尔斯鲁厄研究中心于1994年安装了一个紧凑的回旋加速器系统，用于研究毫米波在高温材料加工领域的技术应用。在完善系统设计的基础上，主要从事各类高级结构和功能陶瓷的脱脂和烧结研究。由于体积加热和增强的烧结动力学，微波的应用可以缩短加工时间，从而降低能耗。此外，微波技术为影响陶瓷材料的微观结构和物理性能提供了独特的可能性。本文将概述毫米波技术在结构陶瓷烧结方面的优势，如Al 2o3, Si 3n4，或tio2 -ZrO 2 -MgO多组分陶瓷，纳米晶氧化物陶瓷，以及PZT压电陶瓷作为最有趣的功能陶瓷之一。
{"title":"Millimeter Wave Sintering of Ceramics","authors":"G. Link, S. Rhee, L. Feher, M. Thumm","doi":"10.1002/9783527612765.CH77","DOIUrl":"https://doi.org/10.1002/9783527612765.CH77","url":null,"abstract":"At the Forschungszentrum Karlsruhe (D), a compact gyrotron system was installed in 1994 to investigate technological application in the field of high temperature materials processing using millimeter waves (mm-waves). Besides the improvement of the system design, research activities are mainly engaged in studies on debindering and sintering of various types of advanced structural and functional ceramics. Due to volumetric heating and enhanced sintering kinetics, the application of microwaves allows a shortening of the processing time, thereby reducing energy consumption. In addition, microwave technology gives the unique possibility of influencing the microstructure and physical properties of the ceramic materials. This article will give an overview of the benefits of the mm-wave technology with respect to the sintering of structural ceramics, such as Al 2 O 3 , Si 3 N 4 , or TiO 2 -ZrO 2 -MgO multicomponent ceramics, nanocrystalline oxide ceramics, as well as PZT piezoceramics as one of the most interesting classes of functional ceramics.","PeriodicalId":9707,"journal":{"name":"Cfi-ceramic Forum International","volume":"400 1","pages":"457-461"},"PeriodicalIF":0.0,"publicationDate":"2007-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86322486","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}
Non-transformation toughened ceramics show the typical brittle material behavior of failure before deformation at room temperature. Thus, strengthening of ceramics due to deformation induced compressive residual stresses has been thought to be not possible. Nevertheless, preliminary investigations had shown that, using ceramic-specific parameters, shot peening can introduce high compressive residual stresses into the near-surface of silicon nitride and improve the load capacity. The aim of the presented investigation was to improve the shot peening conditions in order to extend the increase of load capacity while maintaining the surface integrity. The materials investigated where alumina and silicon nitride, the properties determined where residual stresses, load capacity and topography. The results show that high compressive residual stresses in the GPa-range can be introduced in silicon nitride and alumina which may boost the load capacity of the near surface layers by a factor of up to 9. Only little effect on the surface integrity could be obtained.
{"title":"Shot Peening of Ceramics: Damage or Benefit?","authors":"T. Frey, W. Pfeiffer","doi":"10.1002/3527606580.CH25","DOIUrl":"https://doi.org/10.1002/3527606580.CH25","url":null,"abstract":"Non-transformation toughened ceramics show the typical brittle material behavior of failure before deformation at room temperature. Thus, strengthening of ceramics due to deformation induced compressive residual stresses has been thought to be not possible. Nevertheless, preliminary investigations had shown that, using ceramic-specific parameters, shot peening can introduce high compressive residual stresses into the near-surface of silicon nitride and improve the load capacity. The aim of the presented investigation was to improve the shot peening conditions in order to extend the increase of load capacity while maintaining the surface integrity. The materials investigated where alumina and silicon nitride, the properties determined where residual stresses, load capacity and topography. The results show that high compressive residual stresses in the GPa-range can be introduced in silicon nitride and alumina which may boost the load capacity of the near surface layers by a factor of up to 9. Only little effect on the surface integrity could be obtained.","PeriodicalId":9707,"journal":{"name":"Cfi-ceramic Forum International","volume":"17 1","pages":"185-190"},"PeriodicalIF":0.0,"publicationDate":"2006-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87601238","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}
Powder mixtures containing Al 2 O 3 , SiO 2 and carbon black were calcined at 1625°C to form nanoscaled SiC within Al 2 O 3 by means of the carbothermal reduction of SiO 2 . The prepared powders contained 5 and 10 vol. % SiC. These powders were densified by hot pressing, and composite ceramics with densities up to 99 % obtained. Microstructural analyses of the hot-pressed composites showed a homogeneous distribution of SiC particles with a particle size mainly under 100 nm. The fracture mode was intragranular. The fracture toughness determined by the ICL method using the Niihara approach for Palmqvist cracks was in the range of 5 MPa·m 0,5 . The fracture strength determined in a four-point bending test was around 540 MPa for the hot-pressed samples and around 630 MPa for the hot-pressed and post-annealed samples.
{"title":"Preparation of Al2O3/SiC nanocomposites with in-situ formed SiC","authors":"J. Hopf, M. Aslan, H. Schmidt","doi":"10.22028/D291-24534","DOIUrl":"https://doi.org/10.22028/D291-24534","url":null,"abstract":"Powder mixtures containing Al 2 O 3 , SiO 2 and carbon black were calcined at 1625°C to form nanoscaled SiC within Al 2 O 3 by means of the carbothermal reduction of SiO 2 . The prepared powders contained 5 and 10 vol. % SiC. These powders were densified by hot pressing, and composite ceramics with densities up to 99 % obtained. Microstructural analyses of the hot-pressed composites showed a homogeneous distribution of SiC particles with a particle size mainly under 100 nm. The fracture mode was intragranular. The fracture toughness determined by the ICL method using the Niihara approach for Palmqvist cracks was in the range of 5 MPa·m 0,5 . The fracture strength determined in a four-point bending test was around 540 MPa for the hot-pressed samples and around 630 MPa for the hot-pressed and post-annealed samples.","PeriodicalId":9707,"journal":{"name":"Cfi-ceramic Forum International","volume":"86 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2006-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90692353","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}
La synthese des nanoparticules ceramiques peut se faire de deux facons differentes qui produisent des particules sans agglomerats et d'une qualite de traitement de surface < 10 nm. La premiere est un processus continu de reaction hydro-thermique qui modifie de facon ciblee la surface, la seconde est un nouveau procede mecano-chimique de moulage. Sur ces bases, on a developpe plusieurs procedes ceramiques, comme par exemple le procede de la feuille coulee pour produire des membranes ceramiques ultra fines dont la taille des pores peut descendre jusque sans le domaine nanometrique, du SIC a grande conductibilite, du moulage a microinjection par utilisation de micro-particules, des revetements catalytiques (d'une technologie nouvelle a base de nanoparticules) ou la production de nanocomposites constitues de nanoparticules ceramiques avec une matrice polymere. D'autres domaines sont par exemple le revetement optiques, les photo-catalyseurs et les utilisations en Sciences de la Vie. A partir de cela se sont crees des technologies qui ont permis la fabrication de plus de quarante nouveaux produits dans les cinq dernieres annees.
{"title":"Potential of ceramic nanoparticles","authors":"H. Schmidt, K. Schmitt, F. Tabellion, R. Drumm","doi":"10.22028/D291-24747","DOIUrl":"https://doi.org/10.22028/D291-24747","url":null,"abstract":"La synthese des nanoparticules ceramiques peut se faire de deux facons differentes qui produisent des particules sans agglomerats et d'une qualite de traitement de surface < 10 nm. La premiere est un processus continu de reaction hydro-thermique qui modifie de facon ciblee la surface, la seconde est un nouveau procede mecano-chimique de moulage. Sur ces bases, on a developpe plusieurs procedes ceramiques, comme par exemple le procede de la feuille coulee pour produire des membranes ceramiques ultra fines dont la taille des pores peut descendre jusque sans le domaine nanometrique, du SIC a grande conductibilite, du moulage a microinjection par utilisation de micro-particules, des revetements catalytiques (d'une technologie nouvelle a base de nanoparticules) ou la production de nanocomposites constitues de nanoparticules ceramiques avec une matrice polymere. D'autres domaines sont par exemple le revetement optiques, les photo-catalyseurs et les utilisations en Sciences de la Vie. A partir de cela se sont crees des technologies qui ont permis la fabrication de plus de quarante nouveaux produits dans les cinq dernieres annees.","PeriodicalId":9707,"journal":{"name":"Cfi-ceramic Forum International","volume":"14 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2003-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81743751","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 : 1987-01-01DOI: 10.1016/0308-9126(89)90986-3
W. Storch, H. Ruf, H. Scholze
{"title":"Basic principles for testing ceramic-bonded grinding wheels by acoustic emission analysis","authors":"W. Storch, H. Ruf, H. Scholze","doi":"10.1016/0308-9126(89)90986-3","DOIUrl":"https://doi.org/10.1016/0308-9126(89)90986-3","url":null,"abstract":"","PeriodicalId":9707,"journal":{"name":"Cfi-ceramic Forum International","volume":"79 1","pages":"18-23"},"PeriodicalIF":0.0,"publicationDate":"1987-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77664645","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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