Mechanical Properties of Pure, Dense Aluminum Oxide as a Function of Temperature and Grain Size

Abstract

The elastic modulus and transverse bend strength of pure, dense alumina specimens were determined as a function of grain size (1 to 250p) and temperature (30" to 1500°C). The elastic modulus was essentially independent of grain size over the temperature range covered. The transverse bend strength for fine-grain-sized alumina was substantially greater than that for larger-grain-sized alumina over the entire temperature range, although, at the highest temperatures, the rate of decrease of strength with temperature was greatest for the he-grained material. Fine-grained alumina (1 to 2 p ) exhibited considerable yielding and nonlinear load-deflection behavior at 1000°C and above. At 150OoC, the 1-to 2-p specimens bent to the limit of the apparatus without fracturing (approximately 7% outer-fiber strain).

An ab initio study of ZrB2–SiC interface strength as a function of temperature: Correlating phononic and electronic thermal contributions

“…May and Kronberg 2 examined loss of strength in MgO single crystals using three point bending tests up to 1000 • C. Later, various studies focused on the effect of temperature on strength of ceramic crystals, metallic single crystals, metallic alloys, and ceramic composites. [3][4][5][6][7][8][9] Fundamentally, lattice expansion associated with increase in temperature has been attributed to loss of strength as a function of temperature. Such reasoning fundamentally reflects change in static properties of lattice (elastic constant, cohesive energy, etc.)…”

Mechanical properties of glass-crystal structures based on corundum

“…The values of the elastic modulus of densely sintered polycrystalline corundum at room temperature are 392 [4], 386-398 GPa [6] and, for different glasses, 60-80 GPa [6]. The elastic modulus of aluminoborosilicate glass of the composition studied here, calculated using the additivity formula [6], is 78 GPa.…”

FABRICATION AND CHARACTERIZATION OF HOT PRESSED Al2O3

“…Washington. *The term gaseous impurities refers to species such as H20, CO 2 , and S, which may be present as physically adsorbed or trapped gases but .re more likely chemically bonded anions. Powders were cold-pressed in graphite dies at about 2000 psi and then vacuum hotpressed.…”

“…The ball-milled material was reported to -have a somewhat finer particle size, due to the reductiGn of calcined agglomerates, but at the expense of increasing the Fe 2 0 3 and Si0 2 impurtifes to 0.0048% and 0.0184%, respectively (9). The BM A1 2 0 3 had been calcined at 1000'C and had beer reported 1o give mostly gamma A" 2 ) 2 with some eta A1 2 0 3 . -'•th particle sizes of 50 to 55 A and purity near 99.99% except for a residual sulfur cot.. .nt of 0.420 (8).…”

“…The most extensively studied materials were Lindet A and B powders (designated A ýnd B AI 2 0 3 ), since they were most commonly used by other investigators (1)(2)(3)(4)(5)(6). Limited tests were also made on three other alumina powders, designated as R A1 2 0 3 1 BM A1 2 0 3 , § and C A1 2 0 3 ".…”