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Journal ArticleDOI

Aluminum nitride shaping by non-aqueous gelcasting of low-viscosity and high solid-loading slurry

01 Mar 2016-Ceramics International (Elsevier)-Vol. 42, Iss: 4, pp 5569-5574
TL;DR: In this paper, a modified non-aqueous gelcasting technique was used to obtain low-viscosity and high solid-loading AlN slurps with a relative density of 65.5% and flexural strength of 42.3% using 1-methyl-2-pyrrolidinone as solvent and Solsperse® 24,000 as dispersant.
About: This article is published in Ceramics International.The article was published on 2016-03-01. It has received 23 citations till now. The article focuses on the topics: Green body & Slurry.
Citations
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Journal ArticleDOI
TL;DR: In this paper, Zirconium dioxide (ZrO2) all-ceramic teeth were fabricated for biological engineering by photosensitive resin based digital light processing (DLP) technology.

92 citations

Journal ArticleDOI
TL;DR: In this article, high solid loading, low viscosity photosensitive ZrO2 suspensions with optimized rheological properties for stereolithography-based additive manufacturing were developed, and the influence of dispersant types, concentrations and solid loading on their dispersion behavior and rheology behavior were studied.

88 citations

Journal ArticleDOI
TL;DR: In this paper, the structural, elastic, thermodynamic, electronic and optical properties of four predicted AlN phases (Pmn21-AlN, Pbam-AlNs, pbca-Alns and Cmcm-Aln) are calculated using first-principles according to density function theory (DFT).

28 citations

Journal ArticleDOI
TL;DR: In this article, a new binder system containing resin components and adopting the powder injection molding technology to fabricate complex-shaped AlN parts was designed, which can accelerate the densification of AlN ceramic and fasten the oxygen on the triangular grain boundary, leaving the clean grain boundary beneficial for high thermal conductivity.
Abstract: Aluminum nitride (AlN) is a promising material for heat sinks and microelectronic applications because of the advantages of high theoretical thermal conductivity, high mechanical strength, good electrical insulation, low dielectric constant and low thermal expansion coefficient. However, the difficulties in shaping complex-shaped parts with a high thermal conductivity have retarded the wide applications of AlN ceramic. Herein, we design a new binder system containing resin components and adopt the powder injection molding technology to fabricate complex-shaped AlN parts. After the debinding process, the special binder system would produce residual carbon, which could react with Al2O3 and result in decreasing oxygen impurity and forming the yttrium-rich aluminates. The yttrium-rich aluminates can accelerate the densification of AlN ceramic and fasten the oxygen on the triangular grain boundary, leaving the clean grain boundary beneficial for high thermal conductivity. The as-prepared AlN parts with complex shape possess a high thermal conductivity of 248 W m−1 K−1.

24 citations

Journal ArticleDOI
TL;DR: In this article, 45S5 bioglass and biphasic calcium phosphate (BCP) bioceramic scaffolds with a diamond lattice structure (porosity of 70%) were manufactured accurately by digital light processing.
Abstract: The porous bioceramic scaffolds require favorable mechanical properties and excellent bioactivity to promote bone repair. In this work, 45S5 bioglass® & biphasic calcium phosphate (BCP) bioceramic scaffolds with a diamond lattice structure (porosity of 70%) were manufactured accurately by digital light processing (DLP). After optimizing the solid loading of bioceramic suspension to 40 vol%, scaffolds with the minimum pore size of 400 µm were fabricated successfully under exposure energy of 12.54 mJ/cm2. In the initial stage of sintering, crystallization occurred during 45S5 bioglass® itself, bioglass also promoted hydroxyapatite (HA) decomposition to tricalcium phosphate (TCP). With extending holding time to 4 h, Si4+ from 45S5 bioglass® diffused into TCP to produce Ca5(PO4)2SiO4, which could enhance the compressive strength of bioceramic scaffolds. Meanwhile, bioglass would assist the growth and roughening of ceramic grains because of the ion-diffusion from bioglass to BCP. However, as holding time extended to 6 h, abnormal grain growth and cracks occurred which would decrease compressive strength. The best value of compressive strength is 1.735 MPa at the holding time of 4 h. 45S5 bioglass® also accelerated ion exchange such as Si4+ and CO32- between bioceramic and SBF solution. This kind of bioceramics may be used as bioactive scaffolds with customizable fine structures and provide potential applications in bone tissue engineering.

24 citations

References
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Journal ArticleDOI
TL;DR: In this paper, the authors used Monte Carlo simulations to find large deviations from the standard Poisson-Boltzmann treatment of the double layer force for divalent counterions at high surface charge densities and at short separations.
Abstract: Using a novel method the force between two charged surfaces with an intervening electrolyte solution has been determined from Monte Carlo simulations. We find large deviations from the standard Poisson–Boltzmann treatment of the so called double layer force for divalent counterions at high surface charge densities and at short separations. The deviations have two causes: (i) Due to the inclusion of the effect of ion–ion correlations the counterions concentrate more towards the charged wall reducing the overlap between the double layers; and (ii) correlated fluctuations in the ion clouds of the two surfaces lead to an attractive interaction of a van der Waals type. For some realistic values of the parameters the attraction overcomes the repulsive part and there is a net attractive force between similarly charged surfaces. This finding leads to a modification of our conceptual understanding of the interaction between charged particles and it shows that the DLVO theory is qualitatively deficient under some, realistic, conditions.

665 citations

Journal Article
TL;DR: In this article, a suspension de poudre ceramique dans une solution de monomeres organiques est coulee dans un moule, and on polymerise in situ le melange de monemeres pour former des pieces gelifiees which seront ensuite sechees and frittees.
Abstract: Dans ce procede, une suspension de poudre ceramique dans une solution de monomeres organiques est coulee dans un moule. On polymerise in situ le melange de monomeres pour former des pieces gelifiees qui seront ensuite sechees et frittees. Le procede peut se pratiquer avec des dispersions aqueuses ou non-aqueuses. On presente les etudes realisees avec des systemes d'acrylamide.

428 citations

Journal ArticleDOI
TL;DR: Gelcasting as discussed by the authors is a combination of polymer chemistry with slip processing and represents minimal departure from standard ceramic processing and has attracted industrial partners and by collaboration between them and the developers, the process is being advanced from the laboratory toward industrial production.
Abstract: Gelcasting, a ceramic forming process, was developed to overcome some of the limitations of other complex-shape forming techniques such as injection molding and slip casting. In gelcasting, a concentrated slurry of ceramic powder in a solution of organic monomers is poured into a mold and then polymerized in situ to form a green body in the shape of the mold cavity. Thus, it is a combination of polymer chemistry with slip processing and represents minimal departure from standard ceramic processing. The simplicity of the process has attracted industrial partners and by collaboration between them and the developers, the process is being advanced from the laboratory toward industrial production.

326 citations

Journal ArticleDOI
TL;DR: Gelcasting is a well-established colloidal processing method with a short forming time, high yields, high green capacity and low-cost machining, and has been used to prepare high-quality and complex-shaped dense/porous ceramic parts.
Abstract: Gelcasting is a well-established colloidal processing method with a short forming time, high yields, high green capacity and low-cost machining, and has been used to prepare high-quality and complex-shaped dense/porous ceramic parts. In this article, we reviewed recent developments in gelcasting technology for ceramic preparation. For environmental pollution reduction during ceramic preparation by gelcasting, the development of low-toxic and nontoxic gelcasting systems is discussed. The occurrence and control of inner stress and surface-exfoliation in ceramic green bodies prepared by gelcasting are analyzed, and then some methods to control and eliminate the inner stress and surface-exfoliation in ceramic gelcast green bodies, especially for colloidal injection molding of ceramics (CIMC) are proposed. Finally, the applications of gelcasting for the fabrication of porous ceramics and complex-shaped ceramics (e.g., microbeads, rutile capacitor, thin-wall rutile tube, refractory nozzle) are summarized.

253 citations