Cyclic fatigue resistance of silica based refractories for Coke ovens

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Kemian tekniikan korkeakoulu | Master's thesis
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Date
2016-09-13
Department
Major/Subject
European Mineral Engineering Course
Mcode
CHEM3006
Degree programme
Erasmus Mundus Minerals and Environmental Programme
Language
en
Pages
77 + 7
Series
Abstract
The refractory linings of Coke oven walls at Coke Plant 2 of TATA Steel IJmuiden are in the process of replacement. The campaign life of the new ovens is expected to exceed 30 years. During the service the linings are exposed to cyclic thermo-mechanical loads. Over time the loads cause cracking and degradation of the linings. This study investigates the resistance of two types of silica based refractories to cyclic fatigue failure for material selection purposes. The typical methods approached in previous studies to address fatigue failure in materials are reviewed and their applicability to fulfill the aims of this study is discussed. A strain-controlled test procedure is developed for the existing testing equipment in three point bending and compression setups. Both of the materials are found susceptible to cyclic fatigue failure in the strain-controlled mode. Moreover, the stress-strain envelopes in monotonic and cyclic loading tests are found to be different. Fractographic analysis and other complementary techniques revealed the difference is due to the gradual development of micro-damage during the loading cycles. The formation of micro-damage is found responsible for the less brittle failure occurred in cyclic tests. The fused silica material is found to be less vulnerable to fatigue failure than the crystalline silica brick. The microstructural features of the fused silica material account for its reduced brittleness behavior.
Description
Supervisor
Serna, Rodrigo
Thesis advisor
Andreev, Kirill
Keywords
silica refractories, Coke oven lining, thermo-mechanical loads, cyclic fatigue, fatigue failure mechanism
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