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Jean-pierre Kruth - One of the best experts on this subject based on the ideXlab platform.
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environmental impact modeling of Selective Laser Sintering processes
Rapid Prototyping Journal, 2014Co-Authors: Karel Kellens, Jean-pierre Kruth, Renaldi Renaldi, Wim Dewulf, Joost DuflouAbstract:Purpose – This paper aims to present parametric models to estimate the environmental footprint of the Selective Laser Sintering (SLS)’ production phase, covering energy and resource consumption as well as process emissions. Additive manufacturing processes such as (SLS) are often considered to be more sustainable then conventional manufacturing methods. However, quantitative analyses of the environmental impact of these processes are still limited and mainly focus on energy consumption. Design/methodology/approach – The required Life Cycle Inventory data are collected using the CO2PE! – Methodology, including time, power, consumables and emission studies. Multiple linear regression analyses have been applied to investigate the interrelationships between product design features on the one hand and production time (energy and resource consumption) on the other hand. Findings – The proposed parametric process models provide accurate estimations of the environmental footprint of SLS processes based on two des...
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additive manufacturing of zirconia parts by indirect Selective Laser Sintering
Journal of The European Ceramic Society, 2014Co-Authors: Khuram Shahzad, Jean-pierre Kruth, Jan Deckers, Zhongying Zhang, Jef VleugelsAbstract:Abstract Thermally induced phase separation (TIPS) was used to produce spherical polypropylene–zirconia composite powder for Selective Laser Sintering (SLS). The influence of the composition of the composite starting powder and the SLS parameters on the density and strength of the composite SLS parts was investigated, allowing realizing SLS parts with a relative density of 36%. Pressure infiltration (PI) and warm isostatic pressing (WIPing) were applied to increase the green density of the ZrO 2 –PP SLSed parts. Infiltrating the SLS parts with an aqueous 30 vol.% ZrO 2 suspension allowed to increase the sintered density from 32 to 54%. WIPing (135 °C and 64 MPa) of the SLS and SLS/infiltrated complex shape green polymer–ceramic composite parts prior to debinding and Sintering allowed raising the sintered density of the 3 mol Y 2 O 3 stabilized ZrO 2 parts to 92 and 85%, respectively.
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direct Selective Laser Sintering melting of high density alumina powder layers at elevated temperatures
Physics Procedia, 2014Co-Authors: Jan Deckers, Jean-pierre Kruth, Sebastian Meyers, Jef VleugelsAbstract:Abstract Direct Selective Laser Sintering (SLS) or Selective Laser melting (SLM) are additive manufacturing techniques that can be used to produce three-dimensional ceramic parts directly, without the need for a sacrificial binder. In this paper, a low Laser energy density is applied to SLS/SLM high density powder layers of sub-micrometer alumina at elevated temperatures (up to 800 C ). In order to achieve this, a furnace was designed and built into a commercial SLS machine. This furnace was able to produce a homogeneously heated cylindrical zone with a height of 60 mm and a diameter of 32 mm. After optimizing the layer deposition and Laser scanning parameters, two ceramic parts with a density up to 85% and grain sizes as low as 5 μ m were successfully produced.
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additive manufacturing of alumina parts by indirect Selective Laser Sintering and post processing
Journal of Materials Processing Technology, 2013Co-Authors: Khuram Shahzad, Jean-pierre Kruth, Jan Deckers, Jef VleugelsAbstract:Abstract Innovative powder preparation and post-processing techniques can be employed to obtain high density ceramic parts by means of indirect Selective Laser Sintering. Thermally induced phase separation (TIPS) was used to produce polymer and polymer–ceramic composite particles. The effect of polymer concentration, cooling rate, stirring and alumina particles on polymer and polymer–ceramic composite particles was investigated. Homogeneous spherical alumina–polypropylene (PP) composite powder was synthesized by TIPS for Selective Laser Sintering (SLS). Green Al2O3–PP component parts with a density of 34% could be produced by conventional SLS of the polymer under optimized Laser power, scan speed, scan spacing and powder preheating temperature. Various post-processing techniques like pressure infiltration (PI), warm isostatic pressing (WIPing) or a combination of both were applied to increase the green density of the Al2O3–PP SLM parts. Infiltrating the open porosity green SLS parts with a 30 vol% alumina-powder based ethanol suspension allowed to increase the sintered density, i.e. after polymer debinding and pressureless Sintering in air at 1600 °C, from 38 to 64% of the theoretical density (TD). WIPing of the SLS and SLS/infiltrated green parts at 135 °C and 64 MPa allowed raising the green density up to 93 and 83% TD and a sintered density up to 89 and 88% TD, respectively.
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isostatic pressing assisted indirect Selective Laser Sintering of alumina components
Rapid Prototyping Journal, 2012Co-Authors: Jan Deckers, Khuram Shahzad, Jef Vleugels, Jean-pierre KruthAbstract:Purpose – The purpose of this paper is to assess a new powder metallurgy process to make alumina parts through indirect Selective Laser Sintering (SLS). Density measurements, some geometrical assessments and scanning electron microscopy (SEM) microstructural analyses are performed after each stage of the process, allowing an objective overview to be provided of the challenges and possibilities for the processing of high density technical ceramic parts through SLS of ball milled alumina/polyamide powder agglomerates.Design/methodology/approach – The powder production by ball milling, SLS, cold isostatic pressing (CIP) or quasi isostatic pressing (QIP), debinding and Sintering (FS) stages of the powder metallurgy process were sequentially investigated.Findings – Alumina parts with a density up to 94.1 per cent could be produced by a powder metallurgy process containing an SLS step. Microstructural investigation of the sintered samples reveals an alumina matrix with a grain size of ∼5 μm and two different ki...
Jef Vleugels - One of the best experts on this subject based on the ideXlab platform.
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additive manufacturing of zirconia parts by indirect Selective Laser Sintering
Journal of The European Ceramic Society, 2014Co-Authors: Khuram Shahzad, Jean-pierre Kruth, Jan Deckers, Zhongying Zhang, Jef VleugelsAbstract:Abstract Thermally induced phase separation (TIPS) was used to produce spherical polypropylene–zirconia composite powder for Selective Laser Sintering (SLS). The influence of the composition of the composite starting powder and the SLS parameters on the density and strength of the composite SLS parts was investigated, allowing realizing SLS parts with a relative density of 36%. Pressure infiltration (PI) and warm isostatic pressing (WIPing) were applied to increase the green density of the ZrO 2 –PP SLSed parts. Infiltrating the SLS parts with an aqueous 30 vol.% ZrO 2 suspension allowed to increase the sintered density from 32 to 54%. WIPing (135 °C and 64 MPa) of the SLS and SLS/infiltrated complex shape green polymer–ceramic composite parts prior to debinding and Sintering allowed raising the sintered density of the 3 mol Y 2 O 3 stabilized ZrO 2 parts to 92 and 85%, respectively.
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direct Selective Laser Sintering melting of high density alumina powder layers at elevated temperatures
Physics Procedia, 2014Co-Authors: Jan Deckers, Jean-pierre Kruth, Sebastian Meyers, Jef VleugelsAbstract:Abstract Direct Selective Laser Sintering (SLS) or Selective Laser melting (SLM) are additive manufacturing techniques that can be used to produce three-dimensional ceramic parts directly, without the need for a sacrificial binder. In this paper, a low Laser energy density is applied to SLS/SLM high density powder layers of sub-micrometer alumina at elevated temperatures (up to 800 C ). In order to achieve this, a furnace was designed and built into a commercial SLS machine. This furnace was able to produce a homogeneously heated cylindrical zone with a height of 60 mm and a diameter of 32 mm. After optimizing the layer deposition and Laser scanning parameters, two ceramic parts with a density up to 85% and grain sizes as low as 5 μ m were successfully produced.
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additive manufacturing of alumina parts by indirect Selective Laser Sintering and post processing
Journal of Materials Processing Technology, 2013Co-Authors: Khuram Shahzad, Jean-pierre Kruth, Jan Deckers, Jef VleugelsAbstract:Abstract Innovative powder preparation and post-processing techniques can be employed to obtain high density ceramic parts by means of indirect Selective Laser Sintering. Thermally induced phase separation (TIPS) was used to produce polymer and polymer–ceramic composite particles. The effect of polymer concentration, cooling rate, stirring and alumina particles on polymer and polymer–ceramic composite particles was investigated. Homogeneous spherical alumina–polypropylene (PP) composite powder was synthesized by TIPS for Selective Laser Sintering (SLS). Green Al2O3–PP component parts with a density of 34% could be produced by conventional SLS of the polymer under optimized Laser power, scan speed, scan spacing and powder preheating temperature. Various post-processing techniques like pressure infiltration (PI), warm isostatic pressing (WIPing) or a combination of both were applied to increase the green density of the Al2O3–PP SLM parts. Infiltrating the open porosity green SLS parts with a 30 vol% alumina-powder based ethanol suspension allowed to increase the sintered density, i.e. after polymer debinding and pressureless Sintering in air at 1600 °C, from 38 to 64% of the theoretical density (TD). WIPing of the SLS and SLS/infiltrated green parts at 135 °C and 64 MPa allowed raising the green density up to 93 and 83% TD and a sintered density up to 89 and 88% TD, respectively.
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isostatic pressing assisted indirect Selective Laser Sintering of alumina components
Rapid Prototyping Journal, 2012Co-Authors: Jan Deckers, Khuram Shahzad, Jef Vleugels, Jean-pierre KruthAbstract:Purpose – The purpose of this paper is to assess a new powder metallurgy process to make alumina parts through indirect Selective Laser Sintering (SLS). Density measurements, some geometrical assessments and scanning electron microscopy (SEM) microstructural analyses are performed after each stage of the process, allowing an objective overview to be provided of the challenges and possibilities for the processing of high density technical ceramic parts through SLS of ball milled alumina/polyamide powder agglomerates.Design/methodology/approach – The powder production by ball milling, SLS, cold isostatic pressing (CIP) or quasi isostatic pressing (QIP), debinding and Sintering (FS) stages of the powder metallurgy process were sequentially investigated.Findings – Alumina parts with a density up to 94.1 per cent could be produced by a powder metallurgy process containing an SLS step. Microstructural investigation of the sintered samples reveals an alumina matrix with a grain size of ∼5 μm and two different ki...
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preparation and indirect Selective Laser Sintering of alumina pa microspheres
Ceramics International, 2012Co-Authors: Khuram Shahzad, Jean-pierre Kruth, Jan Deckers, Stijn Boury, Bram Neirinck, Jef VleugelsAbstract:Abstract Indirect Selective Laser Sintering (SLS) is a promising additive manufacturing technique to produce ceramic parts with complex shapes in a two-step process. In the first step, the polymer phase in a deposited polymer/alumina composite microsphere layer is locally molten by a scanning Laser beam, resulting in local ceramic particle bonding. In the second step, the binder is removed from the green parts by slowly heating and subsequently furnace sintered to increase the density. In this work, polyamide 12 and submicrometer sized alumina were used. Homogeneous spherical composite powders in the form of microspheres were prepared by a novel phase inversion technique. The composite powder showed good flowability and formability. Differential scanning calorimetry (DSC) was used to determine the thermal properties and Laser processing window of the composite powder. The effect of the Laser beam scanning parameters such as Laser power, scan speed and scan spacing on the fabrication of green parts was assessed. Green parts were subsequently debinded and furnace sintered to produce crack-free alumina components. The sintered density of the parts however was limited to only 50% of the theoretical density since the intersphere space formed during microsphere deposition and SLS remained after Sintering.
Steven M Howdle - One of the best experts on this subject based on the ideXlab platform.
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Biodegradable Scaffolds for Tissue Engineering Fabricated by Surface Selective Laser Sintering
3rd Kuala Lumpur International Conference on Biomedical Engineering 2006, 2007Co-Authors: V K Popov, E N Antonov, V N Bagratashvili, A N Konovalov, John J A Barry, Alexander Ivanov, Steven M HowdleAbstract:Novel Surface Selective Laser Sintering (SSLS) technique enable precise fabrication of complicated 3D composite biodegradable scaffolds from thermosensitive polylactic and polylactic-co-glycolic acids and even retain bioactivity of incorporated enzymes. The presence of carbon black (CB) nanoparticles in SSLS structures raised concerns about their toxicity and biocompatibility. In present paper we studied this by diverse in vitro analysis using 3T3 fibroblasts, ovine meniscal chondrocytes and C2C12 myoblast cell cultures. All cells “readily” attached to and proliferated on CB containing surfaces. The abundance of live cells spreading out and covering the entire SSLS porous structures confirms their high biocompatibility. Moreover, C2C12 cells in the presence of morphogenetic protein rhBMP-2 have shown strong shift in differentiation pathway from myoblastic to osteoblastic type. These promising results encouraged us to further development of SSLS methodology targeted to custom-designed biodegradable scaffolds and implant fabrication.
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fabrication of polymer scaffolds for tissue engineering using surface Selective Laser Sintering
Laser Physics, 2006Co-Authors: E N Antonov, V N Bagratashvili, Steven M Howdle, A N Konovalov, V K Popov, Ya V PanchenkoAbstract:A new approach to the fabrication of individual implants and scaffolds for tissue engineering—surface Selective Laser Sintering (SSLS)—is proposed and realized. In contrast to the conventional Selective Laser Sintering, the SSLS method makes it possible to sinter polymer microparticles and melt the near-surface layer rather than the microparticle as a whole. The effect of the Laser radiation parameters and the structure and composition of the raw products on the structure and properties of the biomaterials sintered by the Laser radiation is analyzed. This approach makes possible both the application of thermally unstable polymers (e.g., polylactides or polylactoglycolides) and the fabrication of scaffolds with incorporated bioactive proteins. The results obtained yield a regular physical basis for a new technology of the fabrication of various polymer scaffolds that represent important materials and elements of modern tissue engineering. The flexibility of the SSLS method is especially important at the stage of investigation of the cell and tissue responses needed for the optimization of the material for a specific application in tissue engineering.
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three dimensional bioactive and biodegradable scaffolds fabricated by surface Selective Laser Sintering
Advanced Materials, 2005Co-Authors: Eugeni N Antonov, V N Bagratashvili, V K Popov, Martin J Whitaker, John J A Barry, Kevin M Shakesheff, Alexei N Konovalov, Steven M HowdleAbstract:A new method of surface-Selective Laser Sintering (SSLS) leads to the fabrication of three-dimensional (3D) composite scaffolds (spatial resolution ∼200 μm) that are both bioactive and biodegradable. Moreover, the scaffolds can have very precise dimensions and intricate structure. Conventionally, in Selective Laser Sintering (SLS), the polymer absorbs infrared (λ=10.6 μm) radiation and this leads to a volumetric absorption by the whole polymer particle. In other words, each particle of polymer is completely melted and fuses to the next in order to form the desired morphology. In our experiments we have used near-infrared (λ=0.97 μm) Laser radiation, which polymer particles do not absorb at all. To initiate the Sintering process a small quantity (< 0.1 wt.-%) of carbon microparticles were homogeneously distributed on the surfaces of the polymer particles. Thus, the melting process was limited to only the surfaces of each particle. The carbon microparticles are strong absorbers of Laser radiation, and this opens up the technique to a range of polymers that up till now could not be processed by Laser Sintering. More importantly, since the Laser melts only the surfaces of the particles, delicate bioactive species trapped within each particle retain their activity throughout the processing. We have demonstrated the application of this technique by the incorporation of the enzyme ribonuclease A into particles of poly(d,l-lactic) acid (PLA) and the assembly of 3D matrices at three different Laser intensities, using a 0.97 μm wavelength continuous wave (CW) diode Laser.
Jan Deckers - One of the best experts on this subject based on the ideXlab platform.
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additive manufacturing of zirconia parts by indirect Selective Laser Sintering
Journal of The European Ceramic Society, 2014Co-Authors: Khuram Shahzad, Jean-pierre Kruth, Jan Deckers, Zhongying Zhang, Jef VleugelsAbstract:Abstract Thermally induced phase separation (TIPS) was used to produce spherical polypropylene–zirconia composite powder for Selective Laser Sintering (SLS). The influence of the composition of the composite starting powder and the SLS parameters on the density and strength of the composite SLS parts was investigated, allowing realizing SLS parts with a relative density of 36%. Pressure infiltration (PI) and warm isostatic pressing (WIPing) were applied to increase the green density of the ZrO 2 –PP SLSed parts. Infiltrating the SLS parts with an aqueous 30 vol.% ZrO 2 suspension allowed to increase the sintered density from 32 to 54%. WIPing (135 °C and 64 MPa) of the SLS and SLS/infiltrated complex shape green polymer–ceramic composite parts prior to debinding and Sintering allowed raising the sintered density of the 3 mol Y 2 O 3 stabilized ZrO 2 parts to 92 and 85%, respectively.
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direct Selective Laser Sintering melting of high density alumina powder layers at elevated temperatures
Physics Procedia, 2014Co-Authors: Jan Deckers, Jean-pierre Kruth, Sebastian Meyers, Jef VleugelsAbstract:Abstract Direct Selective Laser Sintering (SLS) or Selective Laser melting (SLM) are additive manufacturing techniques that can be used to produce three-dimensional ceramic parts directly, without the need for a sacrificial binder. In this paper, a low Laser energy density is applied to SLS/SLM high density powder layers of sub-micrometer alumina at elevated temperatures (up to 800 C ). In order to achieve this, a furnace was designed and built into a commercial SLS machine. This furnace was able to produce a homogeneously heated cylindrical zone with a height of 60 mm and a diameter of 32 mm. After optimizing the layer deposition and Laser scanning parameters, two ceramic parts with a density up to 85% and grain sizes as low as 5 μ m were successfully produced.
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additive manufacturing of alumina parts by indirect Selective Laser Sintering and post processing
Journal of Materials Processing Technology, 2013Co-Authors: Khuram Shahzad, Jean-pierre Kruth, Jan Deckers, Jef VleugelsAbstract:Abstract Innovative powder preparation and post-processing techniques can be employed to obtain high density ceramic parts by means of indirect Selective Laser Sintering. Thermally induced phase separation (TIPS) was used to produce polymer and polymer–ceramic composite particles. The effect of polymer concentration, cooling rate, stirring and alumina particles on polymer and polymer–ceramic composite particles was investigated. Homogeneous spherical alumina–polypropylene (PP) composite powder was synthesized by TIPS for Selective Laser Sintering (SLS). Green Al2O3–PP component parts with a density of 34% could be produced by conventional SLS of the polymer under optimized Laser power, scan speed, scan spacing and powder preheating temperature. Various post-processing techniques like pressure infiltration (PI), warm isostatic pressing (WIPing) or a combination of both were applied to increase the green density of the Al2O3–PP SLM parts. Infiltrating the open porosity green SLS parts with a 30 vol% alumina-powder based ethanol suspension allowed to increase the sintered density, i.e. after polymer debinding and pressureless Sintering in air at 1600 °C, from 38 to 64% of the theoretical density (TD). WIPing of the SLS and SLS/infiltrated green parts at 135 °C and 64 MPa allowed raising the green density up to 93 and 83% TD and a sintered density up to 89 and 88% TD, respectively.
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isostatic pressing assisted indirect Selective Laser Sintering of alumina components
Rapid Prototyping Journal, 2012Co-Authors: Jan Deckers, Khuram Shahzad, Jef Vleugels, Jean-pierre KruthAbstract:Purpose – The purpose of this paper is to assess a new powder metallurgy process to make alumina parts through indirect Selective Laser Sintering (SLS). Density measurements, some geometrical assessments and scanning electron microscopy (SEM) microstructural analyses are performed after each stage of the process, allowing an objective overview to be provided of the challenges and possibilities for the processing of high density technical ceramic parts through SLS of ball milled alumina/polyamide powder agglomerates.Design/methodology/approach – The powder production by ball milling, SLS, cold isostatic pressing (CIP) or quasi isostatic pressing (QIP), debinding and Sintering (FS) stages of the powder metallurgy process were sequentially investigated.Findings – Alumina parts with a density up to 94.1 per cent could be produced by a powder metallurgy process containing an SLS step. Microstructural investigation of the sintered samples reveals an alumina matrix with a grain size of ∼5 μm and two different ki...
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preparation and indirect Selective Laser Sintering of alumina pa microspheres
Ceramics International, 2012Co-Authors: Khuram Shahzad, Jean-pierre Kruth, Jan Deckers, Stijn Boury, Bram Neirinck, Jef VleugelsAbstract:Abstract Indirect Selective Laser Sintering (SLS) is a promising additive manufacturing technique to produce ceramic parts with complex shapes in a two-step process. In the first step, the polymer phase in a deposited polymer/alumina composite microsphere layer is locally molten by a scanning Laser beam, resulting in local ceramic particle bonding. In the second step, the binder is removed from the green parts by slowly heating and subsequently furnace sintered to increase the density. In this work, polyamide 12 and submicrometer sized alumina were used. Homogeneous spherical composite powders in the form of microspheres were prepared by a novel phase inversion technique. The composite powder showed good flowability and formability. Differential scanning calorimetry (DSC) was used to determine the thermal properties and Laser processing window of the composite powder. The effect of the Laser beam scanning parameters such as Laser power, scan speed and scan spacing on the fabrication of green parts was assessed. Green parts were subsequently debinded and furnace sintered to produce crack-free alumina components. The sintered density of the parts however was limited to only 50% of the theoretical density since the intersphere space formed during microsphere deposition and SLS remained after Sintering.
Khuram Shahzad - One of the best experts on this subject based on the ideXlab platform.
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additive manufacturing of zirconia parts by indirect Selective Laser Sintering
Journal of The European Ceramic Society, 2014Co-Authors: Khuram Shahzad, Jean-pierre Kruth, Jan Deckers, Zhongying Zhang, Jef VleugelsAbstract:Abstract Thermally induced phase separation (TIPS) was used to produce spherical polypropylene–zirconia composite powder for Selective Laser Sintering (SLS). The influence of the composition of the composite starting powder and the SLS parameters on the density and strength of the composite SLS parts was investigated, allowing realizing SLS parts with a relative density of 36%. Pressure infiltration (PI) and warm isostatic pressing (WIPing) were applied to increase the green density of the ZrO 2 –PP SLSed parts. Infiltrating the SLS parts with an aqueous 30 vol.% ZrO 2 suspension allowed to increase the sintered density from 32 to 54%. WIPing (135 °C and 64 MPa) of the SLS and SLS/infiltrated complex shape green polymer–ceramic composite parts prior to debinding and Sintering allowed raising the sintered density of the 3 mol Y 2 O 3 stabilized ZrO 2 parts to 92 and 85%, respectively.
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additive manufacturing of alumina parts by indirect Selective Laser Sintering and post processing
Journal of Materials Processing Technology, 2013Co-Authors: Khuram Shahzad, Jean-pierre Kruth, Jan Deckers, Jef VleugelsAbstract:Abstract Innovative powder preparation and post-processing techniques can be employed to obtain high density ceramic parts by means of indirect Selective Laser Sintering. Thermally induced phase separation (TIPS) was used to produce polymer and polymer–ceramic composite particles. The effect of polymer concentration, cooling rate, stirring and alumina particles on polymer and polymer–ceramic composite particles was investigated. Homogeneous spherical alumina–polypropylene (PP) composite powder was synthesized by TIPS for Selective Laser Sintering (SLS). Green Al2O3–PP component parts with a density of 34% could be produced by conventional SLS of the polymer under optimized Laser power, scan speed, scan spacing and powder preheating temperature. Various post-processing techniques like pressure infiltration (PI), warm isostatic pressing (WIPing) or a combination of both were applied to increase the green density of the Al2O3–PP SLM parts. Infiltrating the open porosity green SLS parts with a 30 vol% alumina-powder based ethanol suspension allowed to increase the sintered density, i.e. after polymer debinding and pressureless Sintering in air at 1600 °C, from 38 to 64% of the theoretical density (TD). WIPing of the SLS and SLS/infiltrated green parts at 135 °C and 64 MPa allowed raising the green density up to 93 and 83% TD and a sintered density up to 89 and 88% TD, respectively.
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isostatic pressing assisted indirect Selective Laser Sintering of alumina components
Rapid Prototyping Journal, 2012Co-Authors: Jan Deckers, Khuram Shahzad, Jef Vleugels, Jean-pierre KruthAbstract:Purpose – The purpose of this paper is to assess a new powder metallurgy process to make alumina parts through indirect Selective Laser Sintering (SLS). Density measurements, some geometrical assessments and scanning electron microscopy (SEM) microstructural analyses are performed after each stage of the process, allowing an objective overview to be provided of the challenges and possibilities for the processing of high density technical ceramic parts through SLS of ball milled alumina/polyamide powder agglomerates.Design/methodology/approach – The powder production by ball milling, SLS, cold isostatic pressing (CIP) or quasi isostatic pressing (QIP), debinding and Sintering (FS) stages of the powder metallurgy process were sequentially investigated.Findings – Alumina parts with a density up to 94.1 per cent could be produced by a powder metallurgy process containing an SLS step. Microstructural investigation of the sintered samples reveals an alumina matrix with a grain size of ∼5 μm and two different ki...
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preparation and indirect Selective Laser Sintering of alumina pa microspheres
Ceramics International, 2012Co-Authors: Khuram Shahzad, Jean-pierre Kruth, Jan Deckers, Stijn Boury, Bram Neirinck, Jef VleugelsAbstract:Abstract Indirect Selective Laser Sintering (SLS) is a promising additive manufacturing technique to produce ceramic parts with complex shapes in a two-step process. In the first step, the polymer phase in a deposited polymer/alumina composite microsphere layer is locally molten by a scanning Laser beam, resulting in local ceramic particle bonding. In the second step, the binder is removed from the green parts by slowly heating and subsequently furnace sintered to increase the density. In this work, polyamide 12 and submicrometer sized alumina were used. Homogeneous spherical composite powders in the form of microspheres were prepared by a novel phase inversion technique. The composite powder showed good flowability and formability. Differential scanning calorimetry (DSC) was used to determine the thermal properties and Laser processing window of the composite powder. The effect of the Laser beam scanning parameters such as Laser power, scan speed and scan spacing on the fabrication of green parts was assessed. Green parts were subsequently debinded and furnace sintered to produce crack-free alumina components. The sintered density of the parts however was limited to only 50% of the theoretical density since the intersphere space formed during microsphere deposition and SLS remained after Sintering.