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Westman, Anna-Karin
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Publikasjoner (10 av 18) Visa alla publikasjoner
Westman, A.-K. & Wei, L.-Y. (2000). TEM study of the interface between HIPed silicon nitride and encapsulation borosilicate glass (ed.). Paper presented at . Journal of Materials Science, 35(11), 2847-2854
Åpne denne publikasjonen i ny fane eller vindu >>TEM study of the interface between HIPed silicon nitride and encapsulation borosilicate glass
2000 (engelsk)Inngår i: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 35, nr 11, s. 2847-2854Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

A transmission electron microscope study has been made of a silicon nitride component with 6 w/o yttrium oxide as a sintering aid hot isostatically pressed (HIP) with an encapsulation glass of borosilicate. The TEM study concentrated on the interface region between ceramic and glass. Two different types of hexagonal boron nitride were formed near the interface. One, with a textured structure, seemed to nucleate heterogeneously on the surfaces of silicon oxynitride grains. The (001) planes of the crystals extended outwards, giving a thickness of approximately 0.5 microns. The other type formed as hexagonally shaped grains separate from the first type and appeared to have grown as several segments in different directions around a nucleus. In each segment BN layers are parallel to each other and perpendicular to their common [001]BM direction. This second type of BN crystal was also detected a little further from the surface within the silicon nitride. The volume fraction of additive glassy phase tended to be lower in this surface region than in the bulk. Possible mechanisms of prevention of encapsulation glass penetration into the porous ceramic component during HIP were discussed

HSV kategori
Forskningsprogram
Materialteknik; Träteknik
Identifikatorer
urn:nbn:se:ltu:diva-16070 (URN)10.1023/A:1004759505321 (DOI)000086419700029 ()2-s2.0-0033738150 (Scopus ID)fa70cbe0-6f73-11db-962b-000ea68e967b (Lokal ID)fa70cbe0-6f73-11db-962b-000ea68e967b (Arkivnummer)fa70cbe0-6f73-11db-962b-000ea68e967b (OAI)
Merknad
Validerad; 2000; 20060921 (cira)Tilgjengelig fra: 2016-09-29 Laget: 2016-09-29 Sist oppdatert: 2018-07-10bibliografisk kontrollert
Westman, A.-K. & Larker, H. T. (1999). Interaction of encapsulation glass and silicon nitride ceramic during HIPing (ed.). Paper presented at . Journal of the European Ceramic Society, 19(16), 2739-2746
Åpne denne publikasjonen i ny fane eller vindu >>Interaction of encapsulation glass and silicon nitride ceramic during HIPing
1999 (engelsk)Inngår i: Journal of the European Ceramic Society, ISSN 0955-2219, E-ISSN 1873-619X, Vol. 19, nr 16, s. 2739-2746Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

Interaction between ceramic compacts and the encapsulation glass during the HIP process has been studied in a model system of silicon nitride and borosilicate glass. Attention has been focused on what happens when the pressure is first applied in the HIP-cycle, i.e. between about 1200 and 1500°C. At this stage the pore system of the ceramic green body is still rather unaffected by sintering. The model system was characterised to evaluate a possible viscous flow of glass into the green body. Two glass compositions, one with high and one with low viscosity, were used, measurements being made of their viscosity and their contact angle on the nitride. Applying Darcy's law it was predicted that the encapsulation glass with the lowest viscosity should penetrate about 1200 microns into the still open pore structure at 1450°C, but this was not observed experimentally. In the calculations no chemical reactions were assumed to take place. However, increases in hardness of heat-treated mixture of glass and silicon nitride powder indicates that nitrogen dissolves in the glass. It is known that nitrogen increases the viscosity of the glass and this would result in a more limited glass intrusion. After HIP the surface region of the dense ceramic exhibited a phase composition gradient of silicon oxynitride, down to approximately 100-200 microns into the bulk

HSV kategori
Forskningsprogram
Materialmekanik
Identifikatorer
urn:nbn:se:ltu:diva-4238 (URN)10.1016/S0955-2219(99)00059-X (DOI)000083466200004 ()22861980-f4a0-11db-ac9f-000ea68e967b (Lokal ID)22861980-f4a0-11db-ac9f-000ea68e967b (Arkivnummer)22861980-f4a0-11db-ac9f-000ea68e967b (OAI)
Merknad
Godkänd; 1999; 20070427 (cira)Tilgjengelig fra: 2016-09-29 Laget: 2016-09-29 Sist oppdatert: 2018-07-10bibliografisk kontrollert
Westman, A.-K., Wei, L.-Y. & Barre, F. (1999). Preparation for TEM of layered samples with fragile microstructure and weak layer interface (ed.). Paper presented at . Microscopy research and technique (Print), 45(3), 198-202
Åpne denne publikasjonen i ny fane eller vindu >>Preparation for TEM of layered samples with fragile microstructure and weak layer interface
1999 (engelsk)Inngår i: Microscopy research and technique (Print), ISSN 1059-910X, E-ISSN 1097-0029, Vol. 45, nr 3, s. 198-202Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

The objective of this work was to prepare for transmission electron microscopy (TEM) a layered structure of materials with fragile microstructure. The samples consisted of two layers of different materials, silicon nitride and borosilicate glass, loosely bonded together. The low strength of the sample resulted in fragmentation during more conventional preparation. However, it was possible to prepare the fragments by mounting them in a titanium specimen carrier with aluminium strips as support. After grinding and polishing, a technique of low-angle ion milling was used to obtain electron beam transparent areas at the nitride/glass interface.

HSV kategori
Forskningsprogram
Träteknik; Materialteknik
Identifikatorer
urn:nbn:se:ltu:diva-7085 (URN)10.1002/(SICI)1097-0029(19990501)45:33.0.CO;2-E (DOI)5673db50-fd61-11db-b816-000ea68e967b (Lokal ID)5673db50-fd61-11db-b816-000ea68e967b (Arkivnummer)5673db50-fd61-11db-b816-000ea68e967b (OAI)
Merknad
Godkänd; 1999; 20070508 (cira)Tilgjengelig fra: 2016-09-29 Laget: 2016-09-29 Sist oppdatert: 2017-11-24bibliografisk kontrollert
Westman, A.-K., Forsberg, S. & Larker, H. T. (1998). Chemical reactions in the system Si3N4-SiO2-B2O3 (ed.). Paper presented at . Journal of the European Ceramic Society, 18(6), 633-640
Åpne denne publikasjonen i ny fane eller vindu >>Chemical reactions in the system Si3N4-SiO2-B2O3
1998 (engelsk)Inngår i: Journal of the European Ceramic Society, ISSN 0955-2219, E-ISSN 1873-619X, Vol. 18, nr 6, s. 633-640Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

Chemical interactions in the system of silicon nitride with borosilicate glass have been studied as part of an evaluation of glass encapsulated HIP. Theoretical calculations have been performed to predict the thermodynamically stable phases under conditions reflecting different stages in a HIP-cycle. Experimental studies were made on heat treated mixtures of the silicon nitride and the silicate glass. These samples were evaluated with X-ray diffraction. At temperatures commonly used for densification, the system reacted to BN and Si2N2O in agreement with the theoretical calculations. At typical temperatures for pressure application no chemical reactions could be detected but the theoretical calculations showed that BN and, for larger amount of silicon nitride, also silicon oxynitride were stable. Minor amounts of the phases may have formed or non-equilibrium conditions could be explanations for the absence of the expected phases

HSV kategori
Forskningsprogram
Materialmekanik
Identifikatorer
urn:nbn:se:ltu:diva-7585 (URN)10.1016/S0955-2219(97)00188-X (DOI)000074140200008 ()5f8a9030-f4a1-11db-ac9f-000ea68e967b (Lokal ID)5f8a9030-f4a1-11db-ac9f-000ea68e967b (Arkivnummer)5f8a9030-f4a1-11db-ac9f-000ea68e967b (OAI)
Merknad
Godkänd; 1998; 20070427 (cira)Tilgjengelig fra: 2016-09-29 Laget: 2016-09-29 Sist oppdatert: 2018-07-10bibliografisk kontrollert
Westman, A.-K. (1998). Hot isostatic pressing of ceramics and influence of glass encapsulation (ed.). (Doctoral dissertation). Paper presented at . Luleå: Luleå tekniska universitet
Åpne denne publikasjonen i ny fane eller vindu >>Hot isostatic pressing of ceramics and influence of glass encapsulation
1998 (engelsk)Doktoravhandling, med artikler (Annet vitenskapelig)
Abstract [en]

Hot isostatic pressing (HIP) is one of the industrial techniques for production of structural ceramics. A high quality of the as-HIPed surface is highly desirable, as it may make it possible to minimise or eliminate costly finishing machining. When a porous ceramic is HIPed, an encapsulation of glass can be applied on the component as a gas tight envelope. Silicon nitride ceramics work well with a borosilicate encapsulation glass but oxides, such as alumina and zirconia, react severely. A protective barrier between the oxides and the borosilicate glass has been developed earlier. With such a system of protective layers it was possible to demonstrate HIP of some oxides, with good mechanical as well as biocompatibility properties as a result. However, there is a difference between the bulk and the surface properties of these materials. A model system of silicon nitride and borosilicate glass was chosen for a more thorough study on interactions between the encapsulation glass and the porous ceramic green body during HIPing. Mechanical, chemical and compositional gradient from the surface of the ceramic into the bulk were studied. Theoretical calculations on chemical reactions in the system Si3N4 - B2O3 were done accompanied by practical experiments. Special attention has been given the part of the HIP-cycle when the pressure is applied and the glass is pushed against the still porous ceramic component. Possible viscous flow of the glass into the ceramic was analysed. TEM-studies of the densified silicon nitride revealed two different types of hexagonal boron nitride formed in the surface region and their role in the encapsulation is discussed. The increased knowledge can beused in work for improved surface quality and for development of intermediate protective layers.

sted, utgiver, år, opplag, sider
Luleå: Luleå tekniska universitet, 1998. s. 152
Serie
Doctoral thesis / Luleå University of Technology 1 jan 1997 → …, ISSN 1402-1544 ; 1998:11
HSV kategori
Forskningsprogram
Konstruktionsmaterial
Identifikatorer
urn:nbn:se:ltu:diva-18754 (URN)a2937450-7b34-11db-8824-000ea68e967b (Lokal ID)a2937450-7b34-11db-8824-000ea68e967b (Arkivnummer)a2937450-7b34-11db-8824-000ea68e967b (OAI)
Merknad
Validerad; 1998; 20061123 (haneit)Tilgjengelig fra: 2016-09-29 Laget: 2016-09-29 Sist oppdatert: 2017-11-24bibliografisk kontrollert
Westman, A.-K., Swain, M., Bell, T. & Bendeli, A. (1998). Ultra-micro indentation technique used for examination of mechanical properties close to a HIPed surface of silicon nitride (ed.). Paper presented at . Journal of the European Ceramic Society, 18(7), 879-890
Åpne denne publikasjonen i ny fane eller vindu >>Ultra-micro indentation technique used for examination of mechanical properties close to a HIPed surface of silicon nitride
1998 (engelsk)Inngår i: Journal of the European Ceramic Society, ISSN 0955-2219, E-ISSN 1873-619X, Vol. 18, nr 7, s. 879-890Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

Ultra-micro indentation using both pointed and spherical tipped indenters has been used to characterize mechanical properties of silicon nitride densified by glass encapsulated hot isostatic pressing (HIP). Young's modulus and hardness have been studied as a function of distance to the interface between silicon nitride and the encapsulation glass. The Young's modulus values are 10 to 20% lower in the close vicinity of the silicon nitride surface compared to bulk values. At distances of 75 to 150 microns from the glass-silicon nitride interface, bulk values are measured. The differences in hardness values between the region close to the surface and the bulk is less pronounced. A possible explanation for these gradients is formation of new phases at the surface of the silicon nitride. Routines for the calibration of both the pointed and spherical tipped indenters are presented

HSV kategori
Forskningsprogram
Materialmekanik
Identifikatorer
urn:nbn:se:ltu:diva-15451 (URN)10.1016/S0955-2219(97)00216-1 (DOI)000074654300018 ()ef715040-f4aa-11db-ac9f-000ea68e967b (Lokal ID)ef715040-f4aa-11db-ac9f-000ea68e967b (Arkivnummer)ef715040-f4aa-11db-ac9f-000ea68e967b (OAI)
Merknad
Godkänd; 1998; 20070427 (cira)Tilgjengelig fra: 2016-09-29 Laget: 2016-09-29 Sist oppdatert: 2018-07-10bibliografisk kontrollert
Adlerborn, J., Björk, L., Westman, A.-K. & Larker, H. (1991). Particulate-reinforced ceramics densified by glass encapsulated HIP (ed.). In: (Ed.), R J Schaefer; Melvin Linzer (Ed.), Hot isostatic pressing: Theory and applications (pp. 211-216). Materials Park, Ohio: ASM International
Åpne denne publikasjonen i ny fane eller vindu >>Particulate-reinforced ceramics densified by glass encapsulated HIP
1991 (engelsk)Inngår i: Hot isostatic pressing: Theory and applications / [ed] R J Schaefer; Melvin Linzer, Materials Park, Ohio: ASM International, 1991, s. 211-216Konferansepaper, Publicerat paper (Fagfellevurdert)
sted, utgiver, år, opplag, sider
Materials Park, Ohio: ASM International, 1991
HSV kategori
Forskningsprogram
Träteknik
Identifikatorer
urn:nbn:se:ltu:diva-35711 (URN)a5d49cdf-b6b7-4f0b-8a1d-dd757e06e421 (Lokal ID)871704137 (ISBN)a5d49cdf-b6b7-4f0b-8a1d-dd757e06e421 (Arkivnummer)a5d49cdf-b6b7-4f0b-8a1d-dd757e06e421 (OAI)
Merknad
Godkänd; 1991; 20110214 (annwes)Tilgjengelig fra: 2016-09-30 Laget: 2016-09-30 Sist oppdatert: 2017-11-25bibliografisk kontrollert
Lepistö, T., Mäntylä, T., Gunnarsson, G., Sveinsdottir, E. L. & Westman, A.-K. (1989). Mechanical properties and aging behaviour of hot isostatically pressed Y-ZrO2 ceramics made of hydrothermally produced and supercritically dried powders (ed.). In: (Ed.), G de With ; R.A. Terpstra; R. Metselaar (Ed.), Euro-ceramics: proceedings of the first European Ceramic Society Conference (ECerS '89) held on 18-23 June 1989 at the Maastricht Exhibition & Congress Centre, the Netherlands. Paper presented at European Ceramic Society Conference : 18/06/1989 - 23/06/1989 (pp. 458-462). London: Elsevier, 3 : Engineering ceramics : including bioceramics
Åpne denne publikasjonen i ny fane eller vindu >>Mechanical properties and aging behaviour of hot isostatically pressed Y-ZrO2 ceramics made of hydrothermally produced and supercritically dried powders
Vise andre…
1989 (engelsk)Inngår i: Euro-ceramics: proceedings of the first European Ceramic Society Conference (ECerS '89) held on 18-23 June 1989 at the Maastricht Exhibition & Congress Centre, the Netherlands / [ed] G de With ; R.A. Terpstra; R. Metselaar, London: Elsevier, 1989, Vol. 3 : Engineering ceramics : including bioceramics, s. 458-462Konferansepaper, Publicerat paper (Fagfellevurdert)
sted, utgiver, år, opplag, sider
London: Elsevier, 1989
Identifikatorer
urn:nbn:se:ltu:diva-29333 (URN)2c5ff235-45a4-43b7-a79f-14d5dd6bfae7 (Lokal ID)2c5ff235-45a4-43b7-a79f-14d5dd6bfae7 (Arkivnummer)2c5ff235-45a4-43b7-a79f-14d5dd6bfae7 (OAI)
Konferanse
European Ceramic Society Conference : 18/06/1989 - 23/06/1989
Merknad
Upprättat; 1989; 20110214 (annwes)Tilgjengelig fra: 2016-09-30 Laget: 2016-09-30 Sist oppdatert: 2017-11-25bibliografisk kontrollert
Tjernlund, A.-K., Hermansson, L., Arvidson, K. & Söremark, R. (1988). Bioimplant materials of hot isostatically pressed aumina and zirconia: mechanical properties and biocompatibility (ed.). In: (Ed.), Derek Taylor (Ed.), Science of Ceramics: [proceedings of the Fourteenth International Conference on Science of Ceramics, held at the University of Kent, Canterburry, Sept. 7-9th 1987]. Paper presented at International Conference on "Science of Ceramics" : 07/09/1987 - 09/09/1987 (pp. 799-804). Stoke-on-Trent: Inst. of Ceramics,
Åpne denne publikasjonen i ny fane eller vindu >>Bioimplant materials of hot isostatically pressed aumina and zirconia: mechanical properties and biocompatibility
1988 (engelsk)Inngår i: Science of Ceramics: [proceedings of the Fourteenth International Conference on Science of Ceramics, held at the University of Kent, Canterburry, Sept. 7-9th 1987] / [ed] Derek Taylor, Stoke-on-Trent: Inst. of Ceramics, , 1988, s. 799-804Konferansepaper, Publicerat paper (Fagfellevurdert)
sted, utgiver, år, opplag, sider
Stoke-on-Trent: Inst. of Ceramics,, 1988
Identifikatorer
urn:nbn:se:ltu:diva-26882 (URN)0249010c-3636-4e7c-b732-8c23ce660340 (Lokal ID)0-901092-41-X (ISBN)0249010c-3636-4e7c-b732-8c23ce660340 (Arkivnummer)0249010c-3636-4e7c-b732-8c23ce660340 (OAI)
Konferanse
International Conference on "Science of Ceramics" : 07/09/1987 - 09/09/1987
Merknad
Upprättat; 1988; 20110214 (annwes)Tilgjengelig fra: 2016-09-30 Laget: 2016-09-30 Sist oppdatert: 2017-11-25bibliografisk kontrollert
Tjernlund, A.-K., Pompe, R., Holmström, M. & Carlsson, R. (1988). Sintering and phase studies in the system Si3N4 - ZrO2 - Al2O3 (ed.). In: (Ed.), Shigeyuki Sōmiya; Noboru Yamamoto; Hiroaki Yanagida (Ed.), Science and technology of Zirconia III: . Paper presented at International Conference on the Science and Technology of Zirconia : 09/09/1986 - 10/09/1986 (pp. 1015-1022). Westerville, Ohio: American Ceramic Society
Åpne denne publikasjonen i ny fane eller vindu >>Sintering and phase studies in the system Si3N4 - ZrO2 - Al2O3
1988 (engelsk)Inngår i: Science and technology of Zirconia III / [ed] Shigeyuki Sōmiya; Noboru Yamamoto; Hiroaki Yanagida, Westerville, Ohio: American Ceramic Society, 1988, s. 1015-1022Konferansepaper, Publicerat paper (Fagfellevurdert)
sted, utgiver, år, opplag, sider
Westerville, Ohio: American Ceramic Society, 1988
Serie
Advances in ceramics ; 24
Identifikatorer
urn:nbn:se:ltu:diva-40050 (URN)f065c3ab-6d2c-4dc7-a839-f4dcab3b3ebb (Lokal ID)0-916094-87-1 (ISBN)f065c3ab-6d2c-4dc7-a839-f4dcab3b3ebb (Arkivnummer)f065c3ab-6d2c-4dc7-a839-f4dcab3b3ebb (OAI)
Konferanse
International Conference on the Science and Technology of Zirconia : 09/09/1986 - 10/09/1986
Merknad
Upprättat; 1988; 20110214 (annwes)Tilgjengelig fra: 2016-10-03 Laget: 2016-10-03 Sist oppdatert: 2017-11-25bibliografisk kontrollert
Organisasjoner