Michael Gasik | Aalto University (original) (raw)
Papers by Michael Gasik
Materials Science Forum, 2003
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Materials Science Forum, 2005
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ABSTRACT
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Multiscale, Multifunctional and Functionally Graded Materials, 2010
ABSTRACT Bioimplants composed of metal and ceramic parts are recently widely used in medicine. It... more ABSTRACT Bioimplants composed of metal and ceramic parts are recently widely used in medicine. It was shown that properties of these implants might be substantially improved with functionally graded materials (FGM). In this work ceramics FGM are considered with emphasis on the optimal processing technique. For ceramic balls and liners of total hip replacement prosthesis optimal sintering procedure is very important irrespectively on the initially selected graded composition profile to get beneficial stresses distribution after sintering and assembling. Different examples are shown and influence of the sintering and gradient profile selection on final properties is discussed.
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Materials Science Forum, 2005
ABSTRACT
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Advanced Healthcare Materials, 2011
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Materials Science Forum, 2005
... 2Safety Technology Authority, Helsinki, Finland amarina.malinina@hut.fi, btina.sammi@tukes. f... more ... 2Safety Technology Authority, Helsinki, Finland amarina.malinina@hut.fi, btina.sammi@tukes. fi, cmgasik@pop.hut.fi ... Fig. 2 demonstrate that low-alumina homogeneous coatings have the worst corrosion resistance with a little difference between 0-75% alumina. ...
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Thermochimica Acta, 2005
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Scripta Materialia, 1996
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Scandinavian Journal of Metallurgy, 2005
ABSTRACT
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Journal of Materials Processing Technology, 2009
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Computer Physics Communications, 1989
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Computational Materials Science, 2000
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Computational Materials Science, 2002
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Chemistry of Materials, 2003
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Journal of the Mechanical Behavior of Biomedical Materials, 2014
Use of hydroxyapatite (HAP) for biomaterials is widely established, often in a combination with t... more Use of hydroxyapatite (HAP) for biomaterials is widely established, often in a combination with titanium alloy substrates in orthopaedic and other implants. Porous HAP-based coatings undergo sintering and heat treatment processes to achieve proper level of density yet avoiding undesirable reactions and phase changes. Thermal expansion mismatch between constituents may also lead to cracking of the coating due to excessive thermal stresses. Thus control of mechanical properties and stress state in the coating during the whole processing cycle represents some challenges when trying to combine conflicting objectives. In this work a method of optimisation of mechanical behaviour of an FGM biomaterial coating or scaffold composed of HAP and beta-tricalcium phosphate (ß-TCP) is considered. For coating on titanium-based substrates which have anatase (TiO2) top layer, thermodynamic equilibrium was analysed and the "safe" compositional path was found to ensure preservation of original ceramic phases during processing. Experimental studies of HAP-TCP sintering kinetics of different compositions were carried out with dilatometry to obtain true shrinkage curves and thermal expansion functions. These data were integrated with thermo-mechanical calculations of stresses and strains in HAP-ß-TCP FGM during processing, which were optimised with respect to minimal stresses, stresses derivatives and curvatures. The beneficial effect of compositional gradation on behaviour of these materials is shown.
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Materials Science and Engineering: C, 2015
Titanium-based implants are widely used in modern clinical practice, but their &a... more Titanium-based implants are widely used in modern clinical practice, but their "optimal" properties in terms of porosity and topology, roughness and hydrophilic parameters are being a subject of intensive discussions. Recent in vitro results have shown a possibility to optimize the surface of an implant with maximal repelling of bacteria (Staphylococcus aureus, Staphylococcus epidermidis) and improvement in human osteogenic and endothelial cell adhesion, proliferation and differentiation. In this work, these different grades titanium implants were tested in vivo using the same analytical methodology. In addition to material parameters, key histomorphometrical parameters such a regeneration area, bone adaptation area and bone-to-implant contact were determined after 2 and 4weeks of implantation in rabbit animal model. Porous implants have more clear differences than non-porous ones, with the best optimum values obtained on hydrothermally treated electrophoretically deposited titanium. These in vivo data correlate well with the optimal prediction made by in vitro tests.
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Materials Science Forum, 2003
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Materials Science Forum, 2005
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ABSTRACT
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Bookmarks Related papers MentionsView impact
Multiscale, Multifunctional and Functionally Graded Materials, 2010
ABSTRACT Bioimplants composed of metal and ceramic parts are recently widely used in medicine. It... more ABSTRACT Bioimplants composed of metal and ceramic parts are recently widely used in medicine. It was shown that properties of these implants might be substantially improved with functionally graded materials (FGM). In this work ceramics FGM are considered with emphasis on the optimal processing technique. For ceramic balls and liners of total hip replacement prosthesis optimal sintering procedure is very important irrespectively on the initially selected graded composition profile to get beneficial stresses distribution after sintering and assembling. Different examples are shown and influence of the sintering and gradient profile selection on final properties is discussed.
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Materials Science Forum, 2005
ABSTRACT
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Advanced Healthcare Materials, 2011
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Materials Science Forum, 2005
... 2Safety Technology Authority, Helsinki, Finland amarina.malinina@hut.fi, btina.sammi@tukes. f... more ... 2Safety Technology Authority, Helsinki, Finland amarina.malinina@hut.fi, btina.sammi@tukes. fi, cmgasik@pop.hut.fi ... Fig. 2 demonstrate that low-alumina homogeneous coatings have the worst corrosion resistance with a little difference between 0-75% alumina. ...
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Thermochimica Acta, 2005
Bookmarks Related papers MentionsView impact
Scripta Materialia, 1996
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Scandinavian Journal of Metallurgy, 2005
ABSTRACT
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Journal of Materials Processing Technology, 2009
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Computer Physics Communications, 1989
Bookmarks Related papers MentionsView impact
Computational Materials Science, 2000
Bookmarks Related papers MentionsView impact
Computational Materials Science, 2002
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Chemistry of Materials, 2003
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Journal of the Mechanical Behavior of Biomedical Materials, 2014
Use of hydroxyapatite (HAP) for biomaterials is widely established, often in a combination with t... more Use of hydroxyapatite (HAP) for biomaterials is widely established, often in a combination with titanium alloy substrates in orthopaedic and other implants. Porous HAP-based coatings undergo sintering and heat treatment processes to achieve proper level of density yet avoiding undesirable reactions and phase changes. Thermal expansion mismatch between constituents may also lead to cracking of the coating due to excessive thermal stresses. Thus control of mechanical properties and stress state in the coating during the whole processing cycle represents some challenges when trying to combine conflicting objectives. In this work a method of optimisation of mechanical behaviour of an FGM biomaterial coating or scaffold composed of HAP and beta-tricalcium phosphate (ß-TCP) is considered. For coating on titanium-based substrates which have anatase (TiO2) top layer, thermodynamic equilibrium was analysed and the "safe" compositional path was found to ensure preservation of original ceramic phases during processing. Experimental studies of HAP-TCP sintering kinetics of different compositions were carried out with dilatometry to obtain true shrinkage curves and thermal expansion functions. These data were integrated with thermo-mechanical calculations of stresses and strains in HAP-ß-TCP FGM during processing, which were optimised with respect to minimal stresses, stresses derivatives and curvatures. The beneficial effect of compositional gradation on behaviour of these materials is shown.
Bookmarks Related papers MentionsView impact
Materials Science and Engineering: C, 2015
Titanium-based implants are widely used in modern clinical practice, but their &a... more Titanium-based implants are widely used in modern clinical practice, but their "optimal" properties in terms of porosity and topology, roughness and hydrophilic parameters are being a subject of intensive discussions. Recent in vitro results have shown a possibility to optimize the surface of an implant with maximal repelling of bacteria (Staphylococcus aureus, Staphylococcus epidermidis) and improvement in human osteogenic and endothelial cell adhesion, proliferation and differentiation. In this work, these different grades titanium implants were tested in vivo using the same analytical methodology. In addition to material parameters, key histomorphometrical parameters such a regeneration area, bone adaptation area and bone-to-implant contact were determined after 2 and 4weeks of implantation in rabbit animal model. Porous implants have more clear differences than non-porous ones, with the best optimum values obtained on hydrothermally treated electrophoretically deposited titanium. These in vivo data correlate well with the optimal prediction made by in vitro tests.
Bookmarks Related papers MentionsView impact