In:
Journal of Materials Research, Springer Science and Business Media LLC, Vol. 16, No. 12 ( 2001-12), p. 3575-3582
Abstract:
Like many other oxides, MnZn ferrite shows a considerably decreased strength in a humid environment. Conventionally one explains this behavior by subcritical crack growth, i.e., a kinetic effect affecting the oxygen–metal bond breaking rate at the crack tip via a reaction with water. The dissociation 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 effect of H 2 O, H 2 S, NH 3 , NO, and CO on the strength of MnZn ferrite have been studied experimentally. For water a clear minimum in strength occurs at relative low partial pressure. For the other gases the data also indicate a minimum. 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 N 2 , is presented. This model can explain the experimentally observed features well. Although kinetic effects induce subcritical crack growth in MnZn ferrites, it is concluded that adsorption is an important strength lowering effect for MnZn ferrite when exposed to active gases.
Type of Medium:
Online Resource
ISSN:
0884-2914
,
2044-5326
DOI:
10.1557/JMR.2001.0490
Language:
English
Publisher:
Springer Science and Business Media LLC
Publication Date:
2001
detail.hit.zdb_id:
54876-5
detail.hit.zdb_id:
2015297-8
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