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Selective Laser Sintering (selective + laser_sintering)

Distribution by Scientific Domains

Polymers and Materials Science	75%

Selected Abstracts

Selective laser sintering of aluminium- and titanium-based composites: processing and characterisation

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 3 2003
S. Vaucher
Abstract Metal matrix composites have been processed by selective laser sintering of metal-ceramic powder blends. The feasibility of manufacturing Al- and Ti-based composites reinforced with various ceramic particles has been assessed. The resulting microstructures are strongly dependent on the laser power and metal-ceramic reactivity. High laser power results in improved density. In-situ grown carbides develop during sintering in AlMg12,SiC and Ti-graphite systems. On the contrary, no discernible reaction has been observed in AlSi20,SiC and Ti-diamond systems. (© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Process Shrinkage and Accuracy during Indirect Laser Sintering of Aluminium,

ADVANCED ENGINEERING MATERIALS, Issue 4 2006
B. Sercombe
In this paper we have investigated the shrinkage and accuracy of indirect selective laser sintered aluminium. The majority of the ,1.2-1.4% linear shrinkage occurs during the infiltration of the skeleton structure. By optimising scale and offset parameters during selective laser sintering of the preforms, accuracy similar to that of casting processes can be achieved. [source]

Development of a 95/5 poly(L -lactide- co -glycolide)/hydroxylapatite and ,-tricalcium phosphate scaffold as bone replacement material via selective laser sintering

JOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 1 2008
Rebecca Louise Simpson
Abstract 95/5 Poly(L -lactide- co -glycolide) was investigated for the role of a porous scaffold, using the selective laser sintering (SLS) fabrication process, with powder sizes of 50,125 and 125,250 ,m. SLS parameters of laser power, laser scan speed, and part bed temperature were altered and the degree of sintering was assessed by scanning electron microscope. Composites of the 125,250 ,-tricalcium phosphate (CAMCERAM® II) were sintered, and SLS settings using 40 wt % CAMCERAM® II were optimized for further tests. Polymer thermal degradation during processing led to a reduction in number and weight averaged molecular weight of 9% and 12%, respectively. Compression tests using the optimized composite sintering parameters gave a Young's modulus, yield strength, and strain at 1% strain offset of 0.13 ± 0.03 GPa, 12.06 ± 2.53 MPa, and 11.39 ± 2.60%, respectively. Porosity was found to be 46.5 ± 1.39%. CT data was used to create an SLS model of a human fourth middle phalanx and a block with designed porosity was fabricated to illustrate the process capabilities. The results have shown that this composite and fabrication method has potential in the fabrication of porous scaffolds for bone tissue engineering. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008 [source]

Direct Laser Sintering of Al2O3,SiO2 Dental Ceramic Components by Layer-Wise Slurry Deposition

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 10 2006
André Gahler
This publication presents a solid freeform fabrication technique for ceramics in the alumina,silica system by layering binder-free, high-loaded ceramic slurries, followed by selective laser sintering. The low melting silica phase and the reaction sintering between silica and alumina favor the rapid prototyping of pure ceramic parts. On the basis of electroacoustic and viscosity measurements, stable slurries from Al2O3/SiO2 powder mixtures and water with a high fluidity have been prepared for the layer deposition with a doctor blade like in tape casting. Layers with a thickness of about 100 ,m were processed. It was found in laser parameter studies that ceramic parts can only be obtained using special alumina contents and laser parameters. But the biphasic approach may allow greater flexibility in the processing regime than is afforded by the use of just one material. The microstructure of these parts depends mainly on the temperature gradient induced by the laser absorption and thermal conduction. The wet shaping facilitates laser-sintered parts with a relatively high density, which could be increased by a thermal post-treatment. [source]

Rapid Prototyping of Piezoelectric Ceramics via Selective Laser Sintering and Gelcasting

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 1 2004
Dong Guo
This article presents a new lost mold rapid prototyping method which combines selective laser sintering (SLS) and gelcasting techniques for fabricating piezoelectric ceramics. SLS was used to fabricate sacrificial molds of the desired structure of the ceramic part. Then aqueous PZT (lead zirconate titanate) suspension was cast in the mold and solidified in situ through formation of a three-dimensional network gel. Because the polymer mold can be easily removed at the initial stage of sintering and the gelcast PZT body has a high green strength, the desired geometry of the PZT part can be completely retained after sintering of the ceramics. Complex-shaped PZT parts were successfully fabricated after using concentrated PZT suspension with low viscosity. Densities and electrical properties, such as the d33, the relative permittivity ,, the dielectric loss tg, and the electromechanical coupling factor Kp of the gelcast PZT parts were also compared with those of the die-pressed PZT samples. The results indicated that the gel-forming process did not deteriorate the electrical properties of the samples, if proper dispersant was selected in developing concentrated ceramic slurry. [source]

Direct Ink-Jet Printing of Vertical Walls

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 8 2002
Xinglong Zhao
Direct jet printing can assemble ceramic powder into a three dimensional shape by firing droplets of ink through a nozzle to build a multiple layered structure. As with stereolithography and selective laser sintering, the surface texture is expected to witness the layered assembly. The ability to create vertical walls by direct ink-jet printing was explored using a test piece based on a maze. The structure and topography are discussed in terms of droplet spreading and drying. [source]