Study on Mass Segregation Phenomenon of Al2O3 Ceramic Slurries during Centrifugal Slip Casting

2012 ◽  
Vol 490-495 ◽  
pp. 3584-3588
Author(s):  
Jing Yuan Yu ◽  
Qiang Li
Keyword(s):  
Slip Casting ◽  
Solid Content ◽  
Green Density ◽  
Centrifugal Acceleration ◽  
Obvious Effect ◽  
Al2o3 Ceramic ◽  
Centrifugal Process ◽  
Segregation Phenomenon ◽  
Mass Segregation ◽  
Microstructure And Mechanical Property

Mass segregation of Al2O3 slurries during centrifugal slip casing has important effect on microstructure and mechanical property of sintered Al2O3 ceramic, so the study on effect of centrifugal process parameters on mass segregation of slurries has significant meaning. Al2O3 ceramic slurries with different solid content varying from 30vol% to 50vol% were prepared. The effect of centrifugal time, centrifugal acceleration and solid content of slurries on green density uniformity of Al2O3 ceramic compacts was studied. The microstructure of centrifuged compacts was observed using scanning electron microscopy (SSX-505). The results show with the increase of centrifugal acceleration and solid content of slurries, the mass segregation of Al2O3 particles with different size increases and decreases, respectively. However, centrifugal time has no obvious effect on green density uniformity. SEM observation shows the green compacts have uniform microstructure when centrifuged at 2860g for 2h with 50vol% slurries.

Preparation of Gradient ZTA Ceramic by Centrifugal Slip Casting Method

2012 ◽  
Vol 569 ◽  
pp. 324-327 ◽  
Author(s):  
Si Kun Wang ◽  
Jing Yuan Yu ◽  
Qiang Li ◽  
Er Yong Zheng ◽  
Yong Gang Duan ◽  
...  
Keyword(s):  
Fracture Strength ◽  
Slip Casting ◽  
Rheological Characteristic ◽  
Solid Content ◽  
Solid Loading ◽  
Green Density ◽  
Casting Method ◽  
High Fracture ◽  
Gradient Distribution ◽  
Strength And Toughness

Gradient Zirconia toughened alumina (ZTA) ceramics with high fracture strength and toughness were prepared using centrifugal slip casting method. Aqueous Al2O3-20vol% ZrO2 slurries with different solid contents were prepared and the rheological characteristic of the slurries were investigated. The effect of solid loading of slurries on green density difference of ZTA ceramic compacts was observed. Mass segregation of Al2O3 and ZrO2 particles were studied. Microstructure and bending property of the sintered ZTA ceramics were investigated. The results show that the segregation phenomenon of Al2O3-ZrO2 slurries comes form the difference of settling velocity of Al2O3 and ZrO2 particles. With the increase of solid content of slurries, the gradient distribution of green density becomes unconspicuous. After sintered at 1550○C for 2 h, the gradient ZTA ceramics centrifuged with 20vol% slurries have high sintered density (99.2% TD) and continuous gradient distribution of Al2O3 and ZrO2 particles. The fracture strength and toughness of gradient ZTA ceramic are 732MPa and 5.4MPam1/2, respectively.

Dense, bubble-free ceramic deposits from aqueous suspensions by electrophoretic deposition

2001 ◽  
Vol 16 (2) ◽  
pp. 321-324 ◽  
Author(s):  
Tetsuo Uchikoshi ◽  
Kiyoshi Ozawa ◽  
Benjamin D. Hatton ◽  
Yoshio Sakka
Keyword(s):  
Electrophoretic Deposition ◽  
Current Density ◽  
Bubble Formation ◽  
Slip Casting ◽  
Green Density ◽  
Laminate Composites ◽  
Aqueous Suspensions ◽  
Sintering Properties ◽  
Current Densities ◽  
Positively Charged

The characteristics of electrophoretic deposition (EPD) of positively charged particles onto a cathode were investigated using aqueous alumina and zirconia suspensions. The deposition was performed using several kinds of metal substrates at different current densities. For most substrate materials, a large number of macropores appeared in the deposit, and their size increased with the current density due to gas bubble formation. However, no macropores were formed in the deposit on a palladium substrate, regardless of the current density. The green density and sintering properties of the EPD deposits on a palladium substrate from aqueous suspensions were the same as from slip casting. Bubble-free zirconia/alumina laminate composites were also fabricated by EPD from aqueous suspensions.

Fabrication of an All-Ceramic Implant by Slip Casting of Nanoscale Zirconia Powder

2020 ◽  
Vol 20 (9) ◽  
pp. 5703-5706
Author(s):  
Dae Sung Kim ◽  
Jong Kook Lee
Keyword(s):  
High Surface ◽  
Slip Casting ◽  
Tetragonal Zirconia ◽  
Solid Content ◽  
Solid Loading ◽  
Forming Process ◽  
Surface Cracking ◽  
All Ceramic ◽  
Mechanical Machining ◽  
Zirconia Implants

Dental implants are typically composed of 3Y-TZP (3 mol% yttria-stabilized tetragonal zirconia polycrystals). Most dental zirconia implants are currently fabricated via mechanical machining. However, during the machining of zirconia green bodies, many cracks form on the surface. To prevent surface crack formation on the implants, shape forming of the zirconia is necessary using methods such as slip casting. Herein, we fabricated green compacts using slip casting, candidate forming process to reduce surface cracking. To fabricate an optimal 3Y-TZP implant by slip casting and sintering, we prepared a suitable 3Y-TZP slurry for slip casting by adjusting the viscosity via pH, dispersant agent content, and solid loading refinement. Green compacts were prepared by the slip casting of all-ceramic zirconia implants fabricated using optimal slurry conditions, for example, 60 wt% solid content, 1 wt% dispersant, pH 12 and post-sintering at 1450 °C for 2 h. All sintered bodies contained a tetragonal phase with a high sintered density of approximately 6.07 g/cm3, good mechanical hardness of approximately 1367 Hv, grain size of 220 nm, and high surface roughness without cracks.

Colloidal Process of Magnesia-Carbon Refractory and Its Sintering Characteristic

2007 ◽  
Vol 280-283 ◽  
pp. 1675-1678 ◽  
Author(s):  
Li Hua Xu ◽  
Zhi Fei Cheng ◽  
Fang Lian ◽  
Ti Zhuang Wang ◽  
Yun Yao
Keyword(s):  
High Performance ◽  
Ph Value ◽  
Compaction Pressure ◽  
Slip Casting ◽  
Metallurgical Industry ◽  
Green Density ◽  
Structural Ceramics ◽  
Dry Pressing ◽  
Excellent Thermal Property ◽  
Selection Of

Carbon-containing refractories are widely used in metallurgical industry due to their excellent thermal property and resistance to corrosion by molten iron. In the present work, slip casting colloidal process, which is used to fabricate high performance structural ceramics, has been introduced into the preparation for magnesia-carbon refractory with selection of suitable dispersant. The results indicated that the curve of zeta-potential of magnesia was similar with that of carbon just containing dispersant and the homogenized mixtures were attained under a controlling of low pH value. Three kinds of preparing routes for green bodies were designed, and all of the final densities and the resultant hardness of sintered bodies using colloidal process were superior to these of the specimen using conventional dry pressing, whereas its high green density can be plausibly observed in dry pressing body because of high compaction pressure used.

Effects of Activators on Compressive Strength of Fly Ash-Based Geopolymers

2011 ◽  
Vol 197-198 ◽  
pp. 830-836
Author(s):  
Dong Min Wang ◽  
Pei Fu Cheng ◽  
Fan Fan ◽  
Yun Fen Hou ◽  
Liang Zhang ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Calcium Oxide ◽  
Water Glass ◽  
Solution Concentration ◽  
Solid Content ◽  
Strength Development ◽  
Obvious Effect ◽  
Compressive Strength Development ◽  
Visible Effect

The effects of different activators on compressive strength of fly ash-based geopolymers have been studied. It is discovered that, alkali solution doesn’t have obvious effect, while Na2SiO3 solution has visible effect, the strength of samples rise with the increase of Na2SiO3 solution concentration. The effect of K2SiO3 solution is more obvious than Na2SiO3 solution, the strength of samples tend to first increase and then decrease with the increase of K2SiO3 solution concentration. The K2SiO3 solution with concentration of 2 M is the best activator to prepare geopolymers, which has compressive strength of 28.8 MPa at 28 d. When water glass are used as activators, the best modulus and solid content for Na-water glass (Na2O•nSiO2) are 1.2 and 32%, respectively. On this condition the sample’s compressive strength at 28 d is 38.9 MPa. However crystal calcium oxide is harmful for the compressive strength development, which is different with the conclusion accepted abroad.

Sintered Characteristics of 3 Mole% Yttria-Stabilized Zirconia Polycrystals (3Y-TZP) Implants Manufactured by Slip-Casting and Computer Aided Design/Computer Aided Manufacturing (CAD/CAM)

2021 ◽  
Vol 21 (7) ◽  
pp. 3877-3881
Author(s):  
Dae Sung Kim ◽  
Jong Kook Lee
Keyword(s):  
Computer Aided Design ◽  
Slip Casting ◽  
Solid Content ◽  
Computer Aided ◽  
Dental Hospital ◽  
Cad Cam ◽  
Zirconia Crowns ◽  
Comparative Results ◽  
Aided Design ◽  
Zirconia Implants

Two types of dense and toughened 3Y-TZP zirconia implants were fabricated by the sintering of green compacts. Then, the sintered properties of the two implants were compared. Slip-cast and post-sintered all-ceramic zirconia implants were fabricated by the heat treatment at 1450 °C for 2 h using optimal slurry conditions (60 wt% solid content, 1 wt% dispersant, and pH 12). Computer-aided design and manufacturing (CAD/CAM)-machined and post-sintered zirconia crowns, supplied by a dental hospital, were obtained by sintering at 1650 °C for 5 h. The X-ray diffraction results indicated that the phase composition of the slip-casted specimen was completely tetragonal, but the CAD/CAM machined sample was composed of mixed phases of main tetragonal and minor monoclinic crystals. The sintered density and Vickers hardness of the slip-casted specimen were 6.07 g/cm3 and 1367 Hv, respectively, and these were higher than those of the CAD/CAM machined specimen. From the comparative results of the surface microstructure, hardness, and roughness between the two sintered specimens, the slip-casted specimen was found to have higher surface roughness and mechanical hardness, smaller grain size, and less surface micro-cracks than the CAD/CAM machined specimen.

Properties of Screen Printed Ceramic Green Films Determined by Optical Laser Profilometry

2010 ◽  
Vol 654-656 ◽  
pp. 2410-2413 ◽  
Author(s):  
Robert Mücke ◽  
Norbert H. Menzler ◽  
Hans Peter Buchkremer ◽  
Detlev Stöver
Keyword(s):  
Fuel Cell ◽  
Solid Content ◽  
Binder Content ◽  
Thin Layers ◽  
Solid Oxide ◽  
Oxide Fuel ◽  
Green Density ◽  
Dispersing Agent ◽  
Laser Profilometry ◽  
Optical Laser

The green density and roughness of green ceramic layers determine their mechanical and micro structural properties after final sintering. These properties can be measured precisely by laser profilometry. The green density of thin layers (20-50 µm) could quickly be determined as accurately as 0.5% theoretical density. The influence of paste parameters (powder conditioning, solid content, binder, and dispersing agent) on the green density was studied systematically for electrolyte pastes (8 mol.-% yttria stabilised zirconia = 8YSZ) typically used in solid oxide fuel cell applications. It could be shown that a minimal binder content is required to achieve acceptable green densities. Pre-calcination of the powder yielded also significantly higher film densities. Dispersant agents contributed to a smoother surface in any case, however a significant effect on the packing density was only observed for the fine, non-calcined powder.

Study on Preparation and Property of Carbon Fiber/HA Composites by Centrifugal Slip Casting Method

2014 ◽  
Vol 1058 ◽  
pp. 180-184
Author(s):  
Qiang Li ◽  
Jing Yuan Yu ◽  
Xiu Juan Meng
Keyword(s):  
Fracture Toughness ◽  
Carbon Fiber ◽  
Carbon Fibers ◽  
Bending Strength ◽  
Slip Casting ◽  
Rheological Characteristic ◽  
Green Density ◽  
Aminobenzoic Acid ◽  
Casting Method ◽  
Dry Pressing

In this paper, centrifugal slip casting method was use to prepare carbon fiber/HA composites using the nanoHA particles and carbon fibers as initial materials. The morphology of the carbon fiber after modification of p-aminobenzoic acid was observed. The rheological characteristic of the carbon fibers/HA slurries was studied. The effects of the centrifugal acceleration on green density uniformity of carbon fiber/HA composites were analyzed. The bending strength and fracture toughness of carbon fiber/HA composites were measured. The results show the roughness of carbon fibers treated by p-aminobenzoic acid increases. At the pH of 10 and 5 wt% dispersant, the HA slurries with 3 vol% carbon fibers have good fluidity. After centrifuged at 2860 G for 30 min, the green compacts of HA composites have high and uniform the green density. After sintered at 1100°C for 1h, compared with carbon fiber/HA composites prepared by dry pressing, the modified carbon fiber/HA composites prepared by centrifugal slip casting have higher bending strength and fracture toughness of 89.4 MPa and 1.92MPa1/2, respectively.

Preparation and Properties of Cr,Nd:YAG Transparent Ceramics by Slip Casting

2018 ◽  
Vol 281 ◽  
pp. 723-728 ◽  
Author(s):  
Xiu Juan Wan ◽  
Ying Chun Zhang ◽  
Man Wang ◽  
Yang Liu ◽  
Yu Sha Li
Keyword(s):  
High Purity ◽  
Slip Casting ◽  
Solid Content ◽  
Transparent Ceramics ◽  
Green Body ◽  
Vacuum Sintering ◽  
Pure Phase ◽  
Co Doped

In this paper transparent chromium and neodymium co-doped YAG ceramics were prepared by slip casting and vacuum sintering using high purity Al2O3, Y2O3, Nd2O3 and Cr2O3 powders. After mixing the high purity Al2O3, Y2O3, Nd2O3 and Cr2O3 powders under the appropriate percentages, pure phase Cr-Nd-doped YAG powders were preparated via calcining at 1300°C for 2 hours. The slurry with the solid content of 40% was casted by self-pressure slip casting under 25°C and 60% humidity to obtain green body. The green body was dried for 96 hours at 33 °C and 75% humidity and then sintered at 1800 °C for 10 hours in vacuum to obtain Cr,Nd:YAG ceramics finally. The transmittance of 1.0 at.%Cr,1.0 at.% Nd:YAG is nearly 80% at 1064nm, and two absorption peaks of Nd3+ can be seen near 760 nm and 808 nm.

scholarly journals Gradient of mean mass of a star in the field of globular clusters

2007 ◽  
pp. 47-52
Author(s):  
A. Valjarevic
Keyword(s):  
Density Profile ◽  
Surface Density ◽  
Globular Clusters ◽  
Surface Brightness ◽  
Star Clusters ◽  
Segregation Phenomenon ◽  
Mass Segregation ◽  
A Minor ◽  
Minor Correction

Based on the relevant available data, the distributions of masses and apparent magnitudes of stars belonging to globular star clusters are simulated. The simulations are aimed at examining the influence of the mass-segregation phenomenon on the surface-density profile. It is found that a minor correction should be introduced in order to infer the profile of the surface density from that of the surface brightness. .

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