Forming of Ceramic Laminates Comprising Thin Layers of a Few Particles

Abstract

In this paper, a water-based colloidal processing method for manufacturing multilayers with very thin zirconia layers between thick alumina-based layers is presented. The procedure involves the dip coating of green tapes in binder-containing slurries and further lamination and sintering. Dipping studies show that thickness increases with soaking time until a higher limit is achieved, indicating the existence of interaction between slurry and substrate. After sintering, homogeneous, dense, and continuous zirconia layers with thicknesses between 3 and 0.8 lm alternated with 350 lm layers of alumina are obtained, thus meaning that the cross section of these thin layers range from four or five to only one or two grains. Although the residual stresses are estimated to be around 2 GPa, indentation cracks do not shown any interaction when passing through the compressive layers, indicating the existence of a lower thickness limit to achieve a threshold stress.

Free‐Standing Ultrathin Ceramic Foils

“…Because the work was performed on a lab‐scale basis, batch‐wise green film deposition techniques like spin coating of stabilized ceramic suspensions and Langmuir–Blodgett dip coating of monolayers of particles were used. However, automatable deposition techniques like tape casting, 15 electrophoretic deposition, 16 or traditional dip coating 1,17 could also be used for the green film deposition and appear more suited for possible large‐scale fabrication in a later stage.…”

Processing of Alumina and Corresponding Composites

“…Stacking pre-sintered tapes at room temperature and low pressures allows the fabrication of different sequences and thicknesses of the layers depending on the number of tapes and the composition that are stacked together (Figures 8(a) and 8(b); Gurauskis et al, 2007;Sánchez-Herencia et al, 2006). These tapes can be previously dipped in bindercontaining ceramic slurries prior to stacking in order to obtain very thin layers between the tapes (Figure 8(c); Nicolaidis et al, 2008). Sequential slip-casting is extremely versatile in terms of layer thickness (Figures 8(d), 8(e) and 8(f); .…”

“…Typical slip-casting thicknesses are z100-400 mm, and by centrifugal-casting, it is possible to go down to 10 mm. Combination of techniques such as dip coating slip-cast tapes in binder-containing slurries (Nicolaidis, Gurauskis, Baudín, Moreno, & Sánchez-Herencia, 2008) or deposit layers by electrophoresis on presintered slip-cast tapes (Ferrari et al, 2009;Ferrari et al, 2006) and further lamination and sintering allow the fabrication of structures with layers of extremely different sizes. The range of layer widths that can be obtained by EPD is very broad (z1-10 2 mm; Ferrari, Sanchez-Herencia, & Moreno, 1998a& Moreno, , 1998b, and it is possible to locate very thin-layered structures between the load bearing thicker layers that constitute the laminate (Ferrari et al, 2009;Ferrari et al, 2006).…”

“…(a) and (b) Stacking pre-sintered cast tapes of two different compositions (Al 2 O 3 þ 5 vol% YTZP and Al 2 O 3 þ 40 vol% YTZP) at room temperature with low pressures. (a) Dip coating of pre-sintered cast tapes (Al 2 O 3 þ 5 vol% YTZP) in binder-containing slurries (pure ZrO 2 ), stacking at room temperature with low pressures and sintering(Nicolaidis et al, 2008). (d), (e), and (f) Sequential slip-casting.,.…”

Improved Fracture Behavior of Alumina Microstructural Composites with Highly Textured Compressive Layers

“…The competition between single deflection and bifurcation is related to the compressive stresses and may be influenced by the thickness of the TA layers. If the compressive layer is very thin (e.g., few microns) no crack deflection will occur, as demonstrated elsewhere . The degree of crack deflection and/or bifurcation in the TA layers differed from system to system.…”