Plastic forming of alumina from coagulated suspensions

Davies, J.R.; Binner, Jon

doi:10.1016/s0955-2219(00)00011-x

Cited by 24 publications

(14 citation statements)

References 5 publications

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“…15),16) However, increase in the extrusion force caused by the water separation 17) was observed from the bodies during the simple extrusion test. 7),8), 16) This water separation was observed not only in the bodies with small amount of HA but also in the bodies consisting of only HA and water.…”

Section: Results and Discussion 31 Sample Extrusionmentioning

confidence: 99%

Hydraulic alumina as an inorganic binder for extruding and sintering Si3N4 ceramics

Nagaoka

Duran

Göçmez

et al. 2012

J. Ceram. Soc. Japan

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The present work describes the effect of hydraulic alumina (HA) as both a new inorganic binder for extrusion and a sintering additive for silicon nitride (Si 3 N 4 ) ceramics. The addition of small amount of HA imparted flowability and rigidity to the Si 3 N 4 bodies, and could reduce the amount of use of the conventional organic binder to 1/3. Under optimum processing conditions such as amount of the organic binder and water, rods and tubes were successfully extruded using a single screw extruder. Sintered specimens have achieved a relative density of 99% after sintering at 1700 and 1800°C for 4 h. Mechanical properties of the sintered Si 3 N 4 prepared by the body with HA were almost the same as the ones prepared using the conventional additives such as the conventional organic binder and sintering additive, that is, Young's modulus >300 GPa and H v > 1330. These results indicate that small amount of HA addition contributes not only to impart the plasticity but also act as the sintering additive for Si 3 N 4 ceramics.

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Section: Results and Discussion 31 Sample Extrusionmentioning

confidence: 99%

Hydraulic alumina as an inorganic binder for extruding and sintering Si3N4 ceramics

Nagaoka

Duran

Göçmez

et al. 2012

J. Ceram. Soc. Japan

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“…This was caused by water separation from the sample. 19 In the case of the HA paste cured for 8 h, the increasing of the extrusion force was remarkable and had exceeded 5 kN before the piston came in contact with the conical nozzle. However HA samples could be extruded with stability at a low extrusion force as the curing time increased.…”

Section: Extrusion Proceduresmentioning

confidence: 98%

Extrusion of Alumina Ceramics with Hydraulic Alumina without Organic Additives

Nagaoka

Sato

Hotta

et al. 2007

J. Ceram. Soc. Japan

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The extrusion behavior of hydraulic alumina HA pastes prepared by hydration of the HA was studied in order to fabricate the porous alumina ceramics by an extrusion technique. While all the HA paste samples cured for over 8 h were hardened by hydration, different extrusion behaviors were observed. In the early stage of hydration 24 h , water separation from the hardened HA paste was remarkable and the paste was not extruded clearly. On the other hand, even without the addition of an organic plasticizer, the hardened HA pastes cured for a long period 48 h showed good extrusion behavior. Furthermore, the water acted as a fugitive material in the extruded green bodies. Consequently, the open porosity of the sintered at 1400? C for 2 h alumina ceramics could be controlled over a range of 66.9-71.7! by the addition of water ratio of water to HA powder: 0.8 to 1.4 by weight without the use of organic fugitive materials.

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“…Above this point, the force increased rapidly, exceeding 50 kN at the end of the test (Figure 7(a)). The steady increase in force is associated with the occurrence of water exudation during extrusion, known as liquid phase migration [54][55][56][57][58]. The water retention capacity is important to maintain the layer of lubricating liquid between the ceramic particles during the forming process.…”

Section: Extrusion Behavior Of Treated Powdersmentioning

confidence: 99%

Effects of Milling pH and Hydrothermal Treatment on Formation of Nanostructured Boehmite Binder for Alumina Extrusion

Lima

Tercini

Santos

et al. 2017

Journal of Nanomaterials

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The in situ formation of nanostructured aluminum hydroxides on the surface of alumina particles, which can work as inorganic binder, was reported in this paper. The effect of the suspension pH during milling of alumina powder and subsequent hydrothermal treatment for the hydroxide formation and microstructure was depicted. Under acidic pH condition, the formation of hydroxides was not observed. When the pH of suspension changed from acidic to basic during milling, bayerite [Al(OH) 3 ] nanoparticles were formed, but only a fraction of this hydroxide was converted to boehmite (AlOOH) during subsequent hydrothermal treatment. The aluminum hydroxide and oxyhydroxide formed in this condition improved the smoothness of extruded rods and the strength of presintered segments. For the powder milled under basic pH condition, the mechanochemically formed bayerite was completely converted into boehmite nanoparticles during the hydrothermal treatment. The presence of boehmite nanoparticles contributed to improving plasticity during extrusion, which allowed the reduction of organic binder and increased the strength of presintered alumina rods.

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Plastic forming of alumina from coagulated suspensions

Cited by 24 publications

References 5 publications

Hydraulic alumina as an inorganic binder for extruding and sintering Si<sub>3</sub>N<sub>4</sub> ceramics

Hydraulic alumina as an inorganic binder for extruding and sintering Si<sub>3</sub>N<sub>4</sub> ceramics

Extrusion of Alumina Ceramics with Hydraulic Alumina without Organic Additives

Effects of Milling pH and Hydrothermal Treatment on Formation of Nanostructured Boehmite Binder for Alumina Extrusion

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