TY - JOUR
T1 - Minima in the strength of MnZn ferrites
AU - Donners, M.A.H.
AU - Dortmans, L.J.M.G.
AU - With, de, G.
AU - Graaf, de, D.
PY - 2001
Y1 - 2001
N2 - Like many other oxides, MnZn ferrite shows a considerably decreased strength in a humid environment. Conventionally one explains this behavior by subcrit. crack growth, i.e., a kinetic effect affecting the oxygen-metal bond breaking rate at the crack tip via a reaction with water. The dissocn. of water in a proton and hydroxyl ion is considered as crucial. However, it appears that also other gases have a detrimental effect on the strength. In this paper the effects of H2O, H2S, NH3, NO, and CO on the strength of MnZn ferrite have been studied exptl. For water a clear min. in strength occurs at relative low partial pressure. For the other gases the data also indicate a min. An adsorption model taking into account the presence of competitive adsorption mechanisms, involving dissociative and nondissociative adsorption of the adsorbate and the (non)dissociative adsorption of the ever present N2, is presented. This model can explain the exptl. obsd. features well. Although kinetic effects induce subcrit. crack growth in MnZn ferrites, it is concluded that adsorption is an important strength lowering effect for MnZn ferrite when exposed to active gases. [on SciFinder (R)]
AB - Like many other oxides, MnZn ferrite shows a considerably decreased strength in a humid environment. Conventionally one explains this behavior by subcrit. crack growth, i.e., a kinetic effect affecting the oxygen-metal bond breaking rate at the crack tip via a reaction with water. The dissocn. of water in a proton and hydroxyl ion is considered as crucial. However, it appears that also other gases have a detrimental effect on the strength. In this paper the effects of H2O, H2S, NH3, NO, and CO on the strength of MnZn ferrite have been studied exptl. For water a clear min. in strength occurs at relative low partial pressure. For the other gases the data also indicate a min. An adsorption model taking into account the presence of competitive adsorption mechanisms, involving dissociative and nondissociative adsorption of the adsorbate and the (non)dissociative adsorption of the ever present N2, is presented. This model can explain the exptl. obsd. features well. Although kinetic effects induce subcrit. crack growth in MnZn ferrites, it is concluded that adsorption is an important strength lowering effect for MnZn ferrite when exposed to active gases. [on SciFinder (R)]
U2 - 10.1557/JMR.2001.0490
DO - 10.1557/JMR.2001.0490
M3 - Article
SN - 0884-2914
VL - 16
SP - 3575
EP - 3582
JO - Journal of Materials Research
JF - Journal of Materials Research
IS - 12
ER -