Compressive creep testing of refractories at elevated loads—Device, material law and evaluation techniques

Compressive Creep Measurements of Fired Magnesia Bricks at Elevated Temperatures Including Creep Law Parameter Identification and Evaluation by Finite Element Analysis

“…Secondary creep occurs if the strain exponent a is equal to zero. The parameter K is a temperature function and n is the stress exponent [11]. The tertiary creep contribution is of minor importance for the design, as tertiary creep is followed by failure of the component and should be avoided [4].…”

“…The applied stress is σ and E is the Young's modulus. The exact procedure to identify the parameters K, n and a for the Norton-Bailey creep law has been described in [11]. The chemical composition of the fired magnesia brick under research is shown in Table 1.…”

“…For the creep tests, cylindrical samples with a diameter of 35 mm and a height of 70 mm were used and a preload of 100 N (0.104 MPa) was applied axially to fix the sample (Figure 4). The height/diameter ratio of two was suitable for deformation measurement in a zone of the specimen that was not affected by friction from the cylinder's front surfaces [11]. The furnace was heated at 10 K/min to a defined temperature followed by a dwell time of 30 min to reach isothermal conditions in the cylinder.…”

“…In this study, the creep calculation of the lining addressed the heat-up process, where compressive creep is mainly expected, and therefore asymmetric creep was not considered. The creep testing device (CTD) for high-temperature uniaxial compressive creep application and an efficient methodology to identify the creep law parameters used in this work were developed by the Chair of Ceramics (Montanuniversität, Leoben, Austria) [11].…”

“…The Norton-Bailey creep law can be used to describe the behavior in all three creep stages, it is a differential approach which includes the stress dependency on the creep behavior and it can be implemented in finite element programs for the simulation of transient stress states in refractories [13]. The applicability of the Norton-Bailey creep equation to characterize the creep behavior of refractories has been proven by previous studies [10,11,14].…”