Al₂O₃ Nanoparticulate LZS Glass–Ceramic Matrix Composites for Production of Multilayered Materials

Abstract

This work reports the processing steps of Al2O3 (1–5 vol%) nanoparticulate (dV.50 = 13 nm) LZS glass–ceramic matrix (19.58Li2O·11.10ZrO2·69.32SiO2, mol%, dv.50 = 3.5 μm) composites for production of multilayered materials with thermal expansion gradients obtained by tape casting. Suspensions were prepared in water to solids contents ranging from 40 to 47 vol% using ammonium polyacrylate as a deflocculant, and an acrylic copolymer and polyvinyl alcohol as binders. Optimum performance was achieved by sonication and controlling the rheological properties for every step of the process. To prepare the composites, different concentrations (1, 2.5 and 5 vol%) of nanoalumina were added to fresh, as‐prepared LZS suspensions, by changing the solid contents as required to maintain similar viscosities. Green tapes with high uniformity, without macroscopic defects and easy to handle were sintered to relative densities between 89% and 94%. Dense and homogeneous laminates with gradual composition with increasing concentrations of alumina were obtained.

Characterization of Li2O-Al2O3-SiO2 glass-ceramics produced from a Brazilian spodumene concentrate

“…Despite Brazilian glass industries have global importance with a well-consolidated industry and knowhow technology as well as many researches published by Brazilians (e.g. [13][14][15][16][17]), there are few records of industrialscale production of glass-ceramics in Brazil. The chemical composition of Brazilian spodumene matches with the purity requirement and chemical composition of glass-ceramics of the Li 2 O-Al 2 O 3 -SiO 2 (LAS) system.…”

LZS/Al2O3 Glass-Ceramic Composites Sintered by Fast Firing

“…The chemical composition of the milled powder (LZS parent glass) was determined by X-ray fluorescence (Philips, PW 2400, The Netherlands) and atomic absorption spectroscopy (Unican, 969, United Kingdom). Further details on the preparation and processing of the LZS frit are reported in a previous work 20,21 . The differently prepared compositions were labeled as LZS, 1An, 2.5An, and 5An, for contents of nanosized alumina of 0, 1, 2.5, and 5 vol.%.…”

“…The samples were then immediately taken off and cooled to room temperature with cold air. The firing temperatures were selected based on previous work 20,21 . These works use traditional burning processes.…”

“…Furthermore, in applications involving the joining of materials, the thermal expansion requires a fairly narrow compatibility to match the shrinkage, as in glass and glass-ceramic/metal systems for hermetic seals, laser tubes, electronic devices for measuring and monitoring, sealants for solid oxide fuel cells (SOFCs), and substrates used in microelectronic packaging on LTCC technology (low temperature co-fired ceramics) [15][16][17][18][19] . In previous works 20,21 it was demonstrated that the addition of nanosized alumina in a LZS glass-ceramic matrix, produced by conventional sintering, was able to reduce the CTE significantly. This happens because of the alumina affinity with respect to lithium silicates to form β-spodumene (LiAlSi 2 O 6 ), a crystalline phase having a CTE nearly zero (0.9 x 10…”

Copolymers dispersions designed to shaping of ceramic materials

“…However, for the last years, there are not many articles devoted to developing new water-thinnable polymer binders. Most of researchers use commercially available polyacrylic dispersions [22][23][24][25][26][27][28].…”