Selective laser melting is used to manufacture complex structures using an additive manufacturing... more Selective laser melting is used to manufacture complex structures using an additive manufacturing approach with metal powders. It is generally supposed that the quality of the powder plays an important role in the success of the manufacturing process. This is because the powder morphology alongside its size distribution governs the formation of gas pores and controls theflowability. This is important as the process requires successive deposition of uniform layers of powder, which is hindered if the powder does not flow well. In this work, two batches of AlSi10Mg powder with different specifications were characterized in terms of morphology, composition, size distribution, flowability, and apparent density. Bulk samples were created from the powdersusing selective laser melting and the relative densities were compared. One of the metal powders,whichis specially produced for additive manufacturing was found to provide higher quality parts than those fabricated using the other powder,w...
ABSTRACT Precipitation hardening of selective laser melted AlSi10Mg was investigated in terms of ... more ABSTRACT Precipitation hardening of selective laser melted AlSi10Mg was investigated in terms of solution heat treatment and aging duration. The influence on the microstructure and hardness was established, as was the effect on the size and density of Si particles. Although the hardness changes according to the treatment duration, the maximum hardening effect falls short of the hardness of the as-built parts with their characteristic fine microstructure. This is due to the difference in strengthening mechanisms.
Journal of Materials Science: Materials in Medicine, 2006
The manufacture of a scaffold for tissue engineering applications that can control the location a... more The manufacture of a scaffold for tissue engineering applications that can control the location and timing of growth factor release is described. The scaffold is formed by the sintering of poly(DL-lactic acid) (P(DL)LA) microparticles, plasticized with poly(ethylene glycol) (PEG), although the method can be used for many other polymer types. The microparticles were loaded with model proteins, trypsin and horseradish peroxidase (HRP), or recombinant human bone morphogenetic protein-2 (rhBMP-2). Entrapment efficiencies above 75% were achieved using a solid-in-oil-in-water system. Controlled release of active protein was achieved for at least 30 days. Microparticles were built into protein-loaded or protein-free layers and release of the protein was restricted to zones within the scaffold. Cell response to rhBMP-2 was tuneable by changing the dose of the rhBMP-2 released by varying the ratio of protein-loaded and protein-free microparticles within scaffolds. Zonal activity of rhBMP-2 on C2C12 cells was demonstrated. The scaffolds may find utility in applications where gradients of growth factors within 3D templates are required or where zonation of tissue growth is required.
Microhardness Knoop indentation testing of diamond films (13 μm thick) on silicon and on a titan... more Microhardness Knoop indentation testing of diamond films (13 μm thick) on silicon and on a titanium alloy is reported. The measured hardness results were influenced by the substrate, and the results were modelled to give the hardness of the diamond film. Two models were ...
Selective laser melting is used to manufacture complex structures using an additive manufacturing... more Selective laser melting is used to manufacture complex structures using an additive manufacturing approach with metal powders. It is generally supposed that the quality of the powder plays an important role in the success of the manufacturing process. This is because the powder morphology alongside its size distribution governs the formation of gas pores and controls theflowability. This is important as the process requires successive deposition of uniform layers of powder, which is hindered if the powder does not flow well. In this work, two batches of AlSi10Mg powder with different specifications were characterized in terms of morphology, composition, size distribution, flowability, and apparent density. Bulk samples were created from the powdersusing selective laser melting and the relative densities were compared. One of the metal powders,whichis specially produced for additive manufacturing was found to provide higher quality parts than those fabricated using the other powder,w...
ABSTRACT Precipitation hardening of selective laser melted AlSi10Mg was investigated in terms of ... more ABSTRACT Precipitation hardening of selective laser melted AlSi10Mg was investigated in terms of solution heat treatment and aging duration. The influence on the microstructure and hardness was established, as was the effect on the size and density of Si particles. Although the hardness changes according to the treatment duration, the maximum hardening effect falls short of the hardness of the as-built parts with their characteristic fine microstructure. This is due to the difference in strengthening mechanisms.
Journal of Materials Science: Materials in Medicine, 2006
The manufacture of a scaffold for tissue engineering applications that can control the location a... more The manufacture of a scaffold for tissue engineering applications that can control the location and timing of growth factor release is described. The scaffold is formed by the sintering of poly(DL-lactic acid) (P(DL)LA) microparticles, plasticized with poly(ethylene glycol) (PEG), although the method can be used for many other polymer types. The microparticles were loaded with model proteins, trypsin and horseradish peroxidase (HRP), or recombinant human bone morphogenetic protein-2 (rhBMP-2). Entrapment efficiencies above 75% were achieved using a solid-in-oil-in-water system. Controlled release of active protein was achieved for at least 30 days. Microparticles were built into protein-loaded or protein-free layers and release of the protein was restricted to zones within the scaffold. Cell response to rhBMP-2 was tuneable by changing the dose of the rhBMP-2 released by varying the ratio of protein-loaded and protein-free microparticles within scaffolds. Zonal activity of rhBMP-2 on C2C12 cells was demonstrated. The scaffolds may find utility in applications where gradients of growth factors within 3D templates are required or where zonation of tissue growth is required.
Microhardness Knoop indentation testing of diamond films (13 μm thick) on silicon and on a titan... more Microhardness Knoop indentation testing of diamond films (13 μm thick) on silicon and on a titanium alloy is reported. The measured hardness results were influenced by the substrate, and the results were modelled to give the hardness of the diamond film. Two models were ...
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