Ceramic Compositions Having Negative Linear Thermal Expansion

Abstract

Compositions having negative linear thermal expansions ranging from 0 to -0.38~0 have been obtained in two areas of the system lithia-alumina-silica.Petrographic and X-ray examinations indicate the presence of three principal crystalline phases, each of which is a solid solution: 0-eucryptite, 0-spodumene, and a n unidentified quartzlike phase. All compositions were prepared from lithium carbonate, clay, flint, a n d alumina. Some compositions have been prepared which, for all piactical purposes, exhibit no change in length when heated from room temperature to as high as 600°C. Some of these compositions have excellent thermal endurance, withstanding repeated quenchings from a temperature of 1100°C. into water at room temperature.Temp. ("C.1 Fig. 1. linear thermal expansion, Q series.

Solid state sintering of very low and negative thermal expansion ceramics by Spark Plasma Sintering

“…The ability of this sintering technique to obtain dense ceramics will be demonstrated. Previous studies have shown that even for pressureless sintering methods it is necessary to control the sinterability of these ceramics [7] and the variations of thermal expansion coefficient with the LAS composition [8].…”

Influence of lithium oxide as auxiliary flux on the properties of triaxial porcelain bodies

“…Thus, intensive effort has been directed at producing ceramics which contain ␤-eucryptite and ␤-spodumene with relatively high content of Li 2 O. [8][9][10] ␤-Eucryptite and ␤-spodumene containing porcelains, with 8.03-11.86 wt.% Li 2 O, have been produced using kaolin, quartz and Li 2 CO 3 as raw materials via conventional ceramic a Rock A and rock B: Li-bearing pegmatites A and B, respectively. These Li-rich aplite-pegmatite dykes, kindly offered by the Centre of Geology of the University of Porto, were obtained from a deposit (Covas de Barroso district, northern Portugal), whose Li 2 O-content varies between 0.9 and 3.0 wt.%.…”

The temperature–dependence of the volume expansivity and the thermal expansion tensor of petalite between 4.2 K and 600 K

“…Following on from this initial observation, the phase equilibria within the LAS system was subsequently investigated in great detail by Roy and co-workers (Roy and Osborne, 1949;Roy et al, 1950), and from this ternary phase diagram, two regions of negative linear thermal expansivity were identified by Smoke (1951) and Hummel (1951). The first is a localized solid solution centred at a composition corresponding to β-eucryptite (LiAlSiO 4 ; composition 1:1:2), the other, a more extended compositional range β-spodumene solid solution, extends from silica-deficient spodumene, to silica-rich petalite (LiAlSi 4 O 10 ; ideal composition 1:1:8).…”