ISSN:
1551-2916
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
,
Physics
Notes:
The influence of water on the fracture of magnesium aluminate (MgAl2O4) ceramics and spinel single crystals is investigated in order to determine whether adsorption plays an important role during subcritical crack growth as it does for MnZn ferrites, a compound with the same spinel structure. The fracture toughness of porous and dense polycrystalline ceramic and single crystal specimens are determined using a single edge notched beam setup at different crosshead velocities and humidities. Furthermore, in order to investigate whether a preferred plane of fracture is present, electron backscattered diffraction (EBSD) has been performed. It is found that the fracture toughness decreases with increasing humidity for dense ceramics, indicating that adsorption plays an important role as it does for MnZn ferrites. However, porous ceramics only show a sharp decrease between 0% and 2–10% relative humidity (RH) and hardly decreases onwards. This implies that the pores inhibit in some way the effect of adsorption during fracture. The exact mechanism remains unclear. EBSD measurements indicated that a preferred plane is absent. Therefore, the fracture of spinel single crystal along the (100) and (111) planes was chosen for further detailed investigation. It is revealed that between 2% and 40% RH both planes show a reduction in fracture surface energy of ∼46%. Using reported computer simulations results, it can be concluded that the surfaces are partially hydrated when being fractured.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1551-2916.2005.00110.x
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