Modified-starch consolidation of alumina ceramics

Abstract

The alumina ceramics with the homogeneous microstructure and the higher density were fabricated via the modified-starch consolidation process by 1.0 wt% of a modified starch as a consolidator/ binder. The swelling behavior of the modifi ed oxidized tapioca starch was analyzed by optical microscope, and two other corn starches (common corn starch and high amylose corn starch) were also analyzed for comparison. The modifi ed starch used as a binder for the consolidation swelled at about 55 ℃, began to gelatinize at 65 ℃ and then was completely gelatinized at 75 ℃. But the corn starches could not be completely gelatinized even at 80 ℃ for 1 h. The high-strength green bodies (10.6 MPa) with the complex shapes were produced. The green bodies were sintered without any binder burnout procedure at 1 700 ℃ and a relative density of 95.3% was obtained for the sintered bodies, which is similar to that of the sintered sample formed by conventional slip casting. In addition, the effect of temperature on the apparent viscosity of the starch/alumina slurry in the process was investigated, and the corresponding mechanism for the starch consolidation was discussed.

Progress in Hydroxyapatite–Starch Based Sustainable Biomaterials for Biomedical Bone Substitution Applications

“…This is explained by the differences in the surface areas of hydroxyapatite (2 m 2 /g) and starch (0.333 m 2 /g). The theory behind improving the packing behavior of a ceramic slurry is represented by the Furnas model and suggests the replacement of a fraction of fine particles with the same quantity of coarser ones. , This is how shape and dimension of precursor particles are involved in optimization of porous bodies through casting methods. , Various shapes and dimension of hydroxyapatite particles were described in numerous preparation and characterization studies. − Similarly, the variety of extraction sources for starch induces a significant variability in starch particles shapes and dimensions. Starch particles may have oval, elongated, polygonal, spherical, lenticular, or irregular shapes and are grouped, based on their dimensions, as large (above 25 μm), medium (10–25 μm), small (5–10 μm), and very small particles (below 5 μm) …”

“…The theory behind improving the packing behavior of a ceramic slurry is represented by the Furnas model and suggests the replacement of a fraction of fine particles with the same quantity of coarser ones. 174,175 This is how shape and dimension of precursor particles are involved in optimization of porous bodies through casting methods. 150,173 Various shapes and dimension of hydroxyapatite particles were described in numerous preparation and characterization studies.…”

Starch Consolidation Casting of Cordierite Precursor Mixtures—Rheological Behavior and Green Body Properties

“…11 Also clay-based materials, 12,13 and, very recently, porcelain foams 14 have been prepared using starch consolidation casting. At the same time, processing details as well as process optimization and material characterization issues of starch consolidation casting were further investigated for alumina [15][16][17][18][19][20][21][22][23][24] and cordierite. [25][26][27][28][29] While in the first applications of starch consolidation casting to cordierite 2 modified potato starch (modified by hydroxypropylation and crosslinking) has been used, the aforementioned later research [25][26][27][28][29] was primarily focused on the use of native potato starch and native and modified cassava (tapioca) starches.…”

Open-Cellular Alumina Foams with Hierarchical Strut Porosity by Ice Templating: A Thickening Agent Study

“…In addition, the flow behavior for the plain thickening agent/water system (without additions, Figure 2 b) was analyzed. It was shown before in literature that the thickening agents chosen (forming a gel–network with water) are commonly used in ceramic processing (for example starch [ 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 ], guar gum [ 14 , 48 ], methyl cellulose [ 49 , 50 ]). Starch is well known from starch consolidation casting to act as a thickening agent and pore former.…”