Kim Vanmeensel | KU Leuven (original) (raw)

Papers by Kim Vanmeensel

Solid State Phenomena, 2005

Future materials for wear resistant components require a combination of excellent mechanical prop... more Future materials for wear resistant components require a combination of excellent mechanical properties such as hardness and toughness, short processing times and good electrical conductivity to facilitate shaping by electro discharge machining (EDM). In this work, the hardness and fracture toughness of t-ZrO2 based electro conductive composites was optimised, while short processing times below 20 minutes using spark plasma sintering were sufficient to obtain near fully dense materials. The influence of powder processing technique using TiC0.5N0.5 as the starting powder and yttria as a stabiliser on the mechanical properties of ZrO2-TiC0.5N0.5-Al2O3 based composites was investigated. Fully dense Y-TZP based composites possessed an excellent toughness of 9.2 MPa.m1/2 and an increased Vickers hardness of 1397 kg/mm².

Recently innovative solid state / 'meltless' recycling techniques have been developed and... more Recently innovative solid state / 'meltless' recycling techniques have been developed and proposed for the consolidation of aluminium alloy scrap, aiming both at energy and material savings by eliminating the melting step. In this context, a powder metallurgy route is examined as a solid state recycling technique for the fabrication of a two-phase material via Spark Plasma Sin tering. By mixing aluminium atomized powder and machining chips of the same alloy, a two-phase material was produced, w here the powder phase acts as a binder/matrix for the Al scrap. Hardness, density, compression testing along with microstructural and computed tomography analysis of the densified Al 6061 alloy are presented.

Materials Letters, 2021

Abstract Understanding the laser-powder interaction during laser powder bed fusion (LPBF) of comp... more Abstract Understanding the laser-powder interaction during laser powder bed fusion (LPBF) of composite systems is vital in producing robust parts. The currently existing mechanically mixed composite powders are unable to meet the requirements of an ideal powder for the LPBF process, even if the metallic particles remain highly spherical with a second constituent attached to them. It was found that the presence of a reinforcing agent (i.e., B4C) on the surface of metallic particles (i.e., Ti-6Al-4V), rather than its embedment, hinders the full melting of the metallic constituent and deteriorates the powder flowability by creating inter-particle tangling. Despite the significant improvement in the optical absorption caused by the incorporation of the reinforcing agent, the composite powder showed inferior processability compared to the monolithic system.

Metallurgical and Materials Transactions A, 2020

Additive Manufacturing, 2018

Abstract Additive Manufacturing (AM) allows to produce improved, custom made, patient specific an... more Abstract Additive Manufacturing (AM) allows to produce improved, custom made, patient specific and complex shaped medical implants. Both mechanical and biological aspects as well as type of implant and patient specific requirements determine the shape of the implant and the material it will be made of. The current chapter reviews the metals and metallic alloys that can be successfully processed by powder bed fusion AM technologies, focusing on the interrelationship between their chemistry and microstructure, on one hand, and their biological and mechanical behavior, respectively, on the other hand.

Additive Manufacturing, 2020

After laser powder bed fusion (LPBF) of an ultra-strong in situ TiC whisker reinforced β-Ti compo... more After laser powder bed fusion (LPBF) of an ultra-strong in situ TiC whisker reinforced β-Ti composite, this paper investigates the evolution of microstructure and mechanical properties in response to heat treatment at different temperatures. Using in depth nano-SEM and TEM analyses, it is shown that ageing at 400 • C rounds the whiskers, annihilates the strain fields and grows Mo segregated nano-cells, but without improving the ductility. In contrast, ageing at 600 • C enables the transformation of metastable β to a lamellar β + α, leading to a dual phase matrix embedding TiC particles. This is in such a manner that extra ageing at 600 • C coalesces the nano-lamellar α + β microstructure to form a coarser micro-lamellar α + β matrix. This microstructure achieves 66 % of the compressive deformation of Cp-Ti, and over 1400 MPa compressive strength after 1 h of ageing at 600 • C. Despite this success under compression, hard and stiff TiC particles may still cause large spherical fractured voids, severely limiting the plastic deformation under tension.

Material Design & Processing Communications, 2020

Demands for high strength aluminum alloys processed by Laser Powder Bed Fusion (LPBF) are high an... more Demands for high strength aluminum alloys processed by Laser Powder Bed Fusion (LPBF) are high and keep rising. However, expensive new alloy compositions or crack formation in existing alloys hinder its wide applicability. It is known from recent work that addition of grain refiners leads to a fine grain structure enabling crack-free, high strength aluminum LPBF parts. In this research, 1 wt% of Zr was added to Al7050. Furthermore, an excess of Zn was provided in the powder material to compensate for Zn losses during LPBF and to maintain the Mg:Zn ratio required for formation of strong and coherent MgZn 2 precipitates. After a solution and aging heat treatment, the newly developed alloy has an ultimate tensile strength of 500 MPa and Vickers micro-hardness of 200H v-0.5kg. Although the elongation at break of the resulting parts is limited, this research shows promising results for future alloy design of affordable high strength aluminum alloys to be processed by LPBF.

Applied Sciences, 2017

It is reported that the ductility and strength of a metal matrix composite could be concurrently ... more It is reported that the ductility and strength of a metal matrix composite could be concurrently improved if the reinforcing particles were of the size of nanometers and distributed uniformly. In this paper, we revealed that gas atomization solidification could effectively disperse TiB 2 nanoparticles in the Al alloy matrix due to its fast cooling rate and the coherent orientation relationship between TiB 2 particles and α-Al. Besides, nano-TiB 2 led to refined equiaxed grain structures. Furthermore, the composite powders with uniformly embedded nano-TiB 2 showed improved laser absorptivity. The novel composite powders are well suited for selective laser melting.

Dental Materials, 2017

Objective. To assess the influence of surface treatment and thermal annealing on the fourpoint be... more Objective. To assess the influence of surface treatment and thermal annealing on the fourpoint bending strength of two ground dental zirconia grades. Methods. Fully-sintered zirconia specimens (4.0 × 3.0 × 45.0 mm 3) of Y-TZP zirconia (LAVA Plus, 3M ESPE) and Y-TZP/Al 2 O 3 zirconia (ZirTough, Kuraray Noritake) were subjected to four surface treatments: (1) 'GROUND': all surfaces were ground with a diamond-coated grinding wheel on a grinding machine; (2) 'GROUND + HEAT': (1) followed by annealing at 1100 • C for 30 min; (3) 'GROUND + Al 2 O 3 SANDBLASTED': (1) followed by sandblasting using Al 2 O 3 ; (4) 'GROUND + CoJet SANDBLASTED': (1) followed by tribochemical silica (CoJet) sandblasting. Micro-Raman spectroscopy was used to assess the zirconia-phase composition and potentially induced residual stress. The four-point bending strength was measured using a universal material-testing machine. Results. Weibull analysis revealed a substantially higher Weibull modulus and slightly higher characteristic strength for ZirTough (Kuraray Noritake) than for LAVA Plus (3M ESPE). For both zirconia grades, the 'GROUND' zirconia had the lowest Weibull modulus in combination with a high characteristic strength. Sandblasting hardly changed the bending strength but substantially increased the Weibull modulus of the ground zirconia, whereas a thermal treatment increased the Weibull modulus of both zirconia grades but resulted in a significantly lower bending strength. Micro-Raman analysis revealed a higher residual compressive surface stress that correlated with an increased bending strength. Significance. Residual compressive surface stress increased the bending strength of dental zirconia. Thermal annealing substantially reduced the bending strength but increased the consistency (reliability) of 'GROUND' zirconia.

Materials & Design, 2016

Spark plasma sintering is found to be a successful solid state recycling technique for the consol... more Spark plasma sintering is found to be a successful solid state recycling technique for the consolidation of Mg alloy chips. • Fast and full densification/consolidation of Mg alloy machining chips directly into bulk semi-finished products was acheived. • The total recycling route resulted in a finer microstructure than that of the parent material. • The strong bonding and the finer microstructure of the recycled samples improved the mechanical properties.

The journal of adhesive dentistry, Jan 25, 2015

To evaluate the effect of different mechanical pre-treatments on the bond durability to dental zi... more To evaluate the effect of different mechanical pre-treatments on the bond durability to dental zirconia. Fully sintered IPS e.max ZirCAD (Ivoclar Vivadent) blocks were randomly assigned to one of 4 groups: (1) kept as-sintered (control), (2) sandblasted with 50-μm Al2O3 (Danville), or tribochemically silica sandblasted using (3) CoJet (3M ESPE) and (4) SilJet (Danville). The zirconia specimens were additionally pre-treated chemically using a 10-MDP/silane ceramic primer (Clearfil Ceramic Primer, Kuraray Noritake). Two identically pre-treated zirconia blocks were bonded together using resin-composite cement (RelyX Ultimate, 3M ESPE). The specimens were trimmed at the interface to a cylindrical hourglass shape and stored in distilled water (7 days, 37°C), after which they were randomly tested as is or subjected to additional mechanical aging involving cyclic tensile stress (10 N, 10 Hz, 10,000 cycles). Subsequently, the microtensile bond strength was determined and SEM fractographic a...

Solid State Phenomena, 2005

Future materials for wear resistant components require a combination of excellent mechanical prop... more Future materials for wear resistant components require a combination of excellent mechanical properties such as hardness and toughness, short processing times and good electrical conductivity to facilitate shaping by electro discharge machining (EDM). In this work, the hardness and fracture toughness of t-ZrO2 based electro conductive composites was optimised, while short processing times below 20 minutes using spark plasma sintering were sufficient to obtain near fully dense materials. The influence of powder processing technique using TiC0.5N0.5 as the starting powder and yttria as a stabiliser on the mechanical properties of ZrO2-TiC0.5N0.5-Al2O3 based composites was investigated. Fully dense Y-TZP based composites possessed an excellent toughness of 9.2 MPa.m1/2 and an increased Vickers hardness of 1397 kg/mm².

Recently innovative solid state / 'meltless' recycling techniques have been developed and... more Recently innovative solid state / 'meltless' recycling techniques have been developed and proposed for the consolidation of aluminium alloy scrap, aiming both at energy and material savings by eliminating the melting step. In this context, a powder metallurgy route is examined as a solid state recycling technique for the fabrication of a two-phase material via Spark Plasma Sin tering. By mixing aluminium atomized powder and machining chips of the same alloy, a two-phase material was produced, w here the powder phase acts as a binder/matrix for the Al scrap. Hardness, density, compression testing along with microstructural and computed tomography analysis of the densified Al 6061 alloy are presented.

Materials Letters, 2021

Abstract Understanding the laser-powder interaction during laser powder bed fusion (LPBF) of comp... more Abstract Understanding the laser-powder interaction during laser powder bed fusion (LPBF) of composite systems is vital in producing robust parts. The currently existing mechanically mixed composite powders are unable to meet the requirements of an ideal powder for the LPBF process, even if the metallic particles remain highly spherical with a second constituent attached to them. It was found that the presence of a reinforcing agent (i.e., B4C) on the surface of metallic particles (i.e., Ti-6Al-4V), rather than its embedment, hinders the full melting of the metallic constituent and deteriorates the powder flowability by creating inter-particle tangling. Despite the significant improvement in the optical absorption caused by the incorporation of the reinforcing agent, the composite powder showed inferior processability compared to the monolithic system.

Metallurgical and Materials Transactions A, 2020

Additive Manufacturing, 2018

Abstract Additive Manufacturing (AM) allows to produce improved, custom made, patient specific an... more Abstract Additive Manufacturing (AM) allows to produce improved, custom made, patient specific and complex shaped medical implants. Both mechanical and biological aspects as well as type of implant and patient specific requirements determine the shape of the implant and the material it will be made of. The current chapter reviews the metals and metallic alloys that can be successfully processed by powder bed fusion AM technologies, focusing on the interrelationship between their chemistry and microstructure, on one hand, and their biological and mechanical behavior, respectively, on the other hand.

Additive Manufacturing, 2020

After laser powder bed fusion (LPBF) of an ultra-strong in situ TiC whisker reinforced β-Ti compo... more After laser powder bed fusion (LPBF) of an ultra-strong in situ TiC whisker reinforced β-Ti composite, this paper investigates the evolution of microstructure and mechanical properties in response to heat treatment at different temperatures. Using in depth nano-SEM and TEM analyses, it is shown that ageing at 400 • C rounds the whiskers, annihilates the strain fields and grows Mo segregated nano-cells, but without improving the ductility. In contrast, ageing at 600 • C enables the transformation of metastable β to a lamellar β + α, leading to a dual phase matrix embedding TiC particles. This is in such a manner that extra ageing at 600 • C coalesces the nano-lamellar α + β microstructure to form a coarser micro-lamellar α + β matrix. This microstructure achieves 66 % of the compressive deformation of Cp-Ti, and over 1400 MPa compressive strength after 1 h of ageing at 600 • C. Despite this success under compression, hard and stiff TiC particles may still cause large spherical fractured voids, severely limiting the plastic deformation under tension.

Material Design & Processing Communications, 2020

Demands for high strength aluminum alloys processed by Laser Powder Bed Fusion (LPBF) are high an... more Demands for high strength aluminum alloys processed by Laser Powder Bed Fusion (LPBF) are high and keep rising. However, expensive new alloy compositions or crack formation in existing alloys hinder its wide applicability. It is known from recent work that addition of grain refiners leads to a fine grain structure enabling crack-free, high strength aluminum LPBF parts. In this research, 1 wt% of Zr was added to Al7050. Furthermore, an excess of Zn was provided in the powder material to compensate for Zn losses during LPBF and to maintain the Mg:Zn ratio required for formation of strong and coherent MgZn 2 precipitates. After a solution and aging heat treatment, the newly developed alloy has an ultimate tensile strength of 500 MPa and Vickers micro-hardness of 200H v-0.5kg. Although the elongation at break of the resulting parts is limited, this research shows promising results for future alloy design of affordable high strength aluminum alloys to be processed by LPBF.

Applied Sciences, 2017

It is reported that the ductility and strength of a metal matrix composite could be concurrently ... more It is reported that the ductility and strength of a metal matrix composite could be concurrently improved if the reinforcing particles were of the size of nanometers and distributed uniformly. In this paper, we revealed that gas atomization solidification could effectively disperse TiB 2 nanoparticles in the Al alloy matrix due to its fast cooling rate and the coherent orientation relationship between TiB 2 particles and α-Al. Besides, nano-TiB 2 led to refined equiaxed grain structures. Furthermore, the composite powders with uniformly embedded nano-TiB 2 showed improved laser absorptivity. The novel composite powders are well suited for selective laser melting.

Dental Materials, 2017

Objective. To assess the influence of surface treatment and thermal annealing on the fourpoint be... more Objective. To assess the influence of surface treatment and thermal annealing on the fourpoint bending strength of two ground dental zirconia grades. Methods. Fully-sintered zirconia specimens (4.0 × 3.0 × 45.0 mm 3) of Y-TZP zirconia (LAVA Plus, 3M ESPE) and Y-TZP/Al 2 O 3 zirconia (ZirTough, Kuraray Noritake) were subjected to four surface treatments: (1) 'GROUND': all surfaces were ground with a diamond-coated grinding wheel on a grinding machine; (2) 'GROUND + HEAT': (1) followed by annealing at 1100 • C for 30 min; (3) 'GROUND + Al 2 O 3 SANDBLASTED': (1) followed by sandblasting using Al 2 O 3 ; (4) 'GROUND + CoJet SANDBLASTED': (1) followed by tribochemical silica (CoJet) sandblasting. Micro-Raman spectroscopy was used to assess the zirconia-phase composition and potentially induced residual stress. The four-point bending strength was measured using a universal material-testing machine. Results. Weibull analysis revealed a substantially higher Weibull modulus and slightly higher characteristic strength for ZirTough (Kuraray Noritake) than for LAVA Plus (3M ESPE). For both zirconia grades, the 'GROUND' zirconia had the lowest Weibull modulus in combination with a high characteristic strength. Sandblasting hardly changed the bending strength but substantially increased the Weibull modulus of the ground zirconia, whereas a thermal treatment increased the Weibull modulus of both zirconia grades but resulted in a significantly lower bending strength. Micro-Raman analysis revealed a higher residual compressive surface stress that correlated with an increased bending strength. Significance. Residual compressive surface stress increased the bending strength of dental zirconia. Thermal annealing substantially reduced the bending strength but increased the consistency (reliability) of 'GROUND' zirconia.

Materials & Design, 2016

Spark plasma sintering is found to be a successful solid state recycling technique for the consol... more Spark plasma sintering is found to be a successful solid state recycling technique for the consolidation of Mg alloy chips. • Fast and full densification/consolidation of Mg alloy machining chips directly into bulk semi-finished products was acheived. • The total recycling route resulted in a finer microstructure than that of the parent material. • The strong bonding and the finer microstructure of the recycled samples improved the mechanical properties.

The journal of adhesive dentistry, Jan 25, 2015

To evaluate the effect of different mechanical pre-treatments on the bond durability to dental zi... more To evaluate the effect of different mechanical pre-treatments on the bond durability to dental zirconia. Fully sintered IPS e.max ZirCAD (Ivoclar Vivadent) blocks were randomly assigned to one of 4 groups: (1) kept as-sintered (control), (2) sandblasted with 50-μm Al2O3 (Danville), or tribochemically silica sandblasted using (3) CoJet (3M ESPE) and (4) SilJet (Danville). The zirconia specimens were additionally pre-treated chemically using a 10-MDP/silane ceramic primer (Clearfil Ceramic Primer, Kuraray Noritake). Two identically pre-treated zirconia blocks were bonded together using resin-composite cement (RelyX Ultimate, 3M ESPE). The specimens were trimmed at the interface to a cylindrical hourglass shape and stored in distilled water (7 days, 37°C), after which they were randomly tested as is or subjected to additional mechanical aging involving cyclic tensile stress (10 N, 10 Hz, 10,000 cycles). Subsequently, the microtensile bond strength was determined and SEM fractographic a...