Stress Corrosion Cracking of Single‐Crystal Tetragonal ZrO₂(Er₂O₃)

Abstract

The flexure strength of partially‐stabilized tetragonal ZrO2(Er2O3) single‐crystal monofilaments manufactured by the laser‐heated floating zone method was measured as a function of the environment (air versus water) and temperature (from 25° to 800°C) at loading rates spanning three orders of magnitude to ascertain their susceptibility to the environmental conditions. These mechanical tests were completed with parallel tests on fully annealed monofilaments (to relieve the thermal residual stresses induced during growth) and by detailed analysis of the fracture surfaces using scanning electron microscopy and micro‐Raman spectroscopy. While environmental susceptibility of ZrO2(Y2O3) in previous investigations was always associated with the destabilization of the tetragonal phase, monoclinic phase was not detected on the fracture surfaces of the ZrO2(Er2O3) monofilaments and it was concluded that slow crack growth in this material at high temperature or immersed in water was due to stress corrosion cracking.

High‐Temperature Tensile Strength of Er2O3‐Doped ZrO2 Single Crystals

“…Moreover, the scatter in the tensile strength was significantly reduced at 600° and 800°C (as compared with room and higher temperatures). This behavior was already reported in this material when tested in three‐point bending and attributed to the development of subcritical crack growth 4 …”

“…The monofilaments were single crystalline and their microstructure was formed by an intepenetrating network of three tetragonal crystal variants with the 〈111〉 axis parallel to the monofilament axis and size under 10 nm. Additional information about the microstructure could be obtained from previous publications 3,4 and it will not be repeated here.…”

“…Partially stabilized Er‐PSZ monofilaments with nanometric tetragonal domains present excellent properties (in terms of creep resistance and thermal conductivity) for high‐temperature structural applications. However, these merits have been somehow hampered by recent results on the environmental susceptibility of Er‐PSZ at intermediate temperatures (up to 800°C) or in presence of water at ambient temperature 4 . It was found that the average flexure strength decreased markedly with temperature and it was lower in water than in air.…”

Degradation of Nextel™ 610‐based oxide‐oxide ceramic composites by aluminum oxychloride decomposition products

“…The problem was first studied in glass, where the crack growth rate under static loads was found to correlate with the moisture content of the testing environment . More recent work has developed models for glass fibers at room temperature, but work on environmental effects such as EASCG at high temperature and in ceramic materials other than glass is limited, and mostly confined to coarse grained or single‐crystal alumina …”

Degradación ambiental de las propiedades mecánicas de fibras monocristalinas de circona dopada con erbia

“…2, 3 y 4, podemos estimar la cinética de crecimiento de la grieta en un monocristal de circona tetragonal suponiendo que la velocidad de la grieta, ν, sigue una ley del tipo ν=AK n , donde K es el factor de intensidad de tensiones en la punta de la grieta, y A y n son dos constantes de dependen del material y de las condiciones ambientales. Las tensiones de rotura estarán relacionadas con las velocidades de deformación según [24][25][26][27][28] (1) donde E es el módulo elástico, e • es la velocidad de deformación, σ 0 la resistencia inerte, K c la tenacidad e Y una constante geométrica. A partir de la pendiente de la gráfica logσ-log e…”