Steel ladle refractory lining plays an important role in steelmaking refinement as its thermal properties are strictly related to the ladle ability to keep the molten steel temperature constant. This ...work developed a transient numerical analysis, considering temperature dependent refractory properties. A holistic view of the process was proposed to help the refractory design of steel ladles, according to their saving energy capability and overall costs. The numerical description of the ladle cycle used the finite element method (FEM) via commercial software (Abaqus). The average heat flux in the hot face while holding the liquid steel determined the steel ladle energy losses and was compared to evaluate the lining efficiency. The investigations considered the application of distinct working refractories and the presence of an insulating layer. The developed thermal and energy balance tool provided a more inclusive and integrated approach for investigating the energy consumption and thermal history of the steel ladle process, regarding the refractory lining design.
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► Dry joint closure in magnesia–carbon and magnesia–chromite refractory masonry. ► FEM models, direct optical and indirect compressive test in wide temperature range. ► Exponential ...joint closure curves due to non-parallelism of the joint faces. ► Joint closure displacements are reduced with increasing temperature. ► Direct relation between total joint displacement and average joint width.
To support optimisation of refractory masonry structures compressibility of dry joints of magnesia–carbon and magnesia–chromite bricks have been investigated. Laboratory scale tests and finite element modelling have been performed. Measurements done in wide temperature range have shown that the exponential form of the joint closure curve results from gradual closure of initially non-parallel surfaces. The stress needed to close the joint was found to be proportional to the material stiffness. Temperature influences the joint closure by changing the stiffness of material and by reducing the initial joint gap due to thermal expansion.
Furnace linings of magnesia-carbon and micro-porous carbon bricks experience cyclic compressive loads. An experimental programme has been carried out to assess the sensitivity of these materials to ...compressive fatigue failure. Together with room temperature tests, a number of high-temperature tests have been performed. Results of the fatigue tests were analysed together with data from monotonic stress-strain loading and creep tests. Compressive fatigue failure was observed in both the materials and the less brittle material had a shorter fatigue life. The curve relating the fatigue strains with the number of cycles had a classical sigmoid shape with three phases. The strain rates of the secondary (linear) phase showed good correlation with the number of cycles to failure. The grain-matrix interface played a critical role in the initiation and propagation of the fatigue cracks.
Seagrass restoration has often not been successful due to poor site planning, physical disturbance, transplant timing incompatibility, and physical and biological disturbances. As such, these factors ...are important for successfully restoring seagrasses, and global success has greatly increased. We conducted restorations in the mid-Atlantic region of the United States to reestablish this valuable habitat. Our restoration efforts in New Jersey involved transplants of both Zostera marina (eelgrass) and Ruppia maritima (widgeon grass). We found that Z. marina site success and transplant survival increased over the scope of this 4-year investigation (66%–100% and 34%–43%, respectively). However, R. maritima success was heavily dependant upon the year planted; with limited success in 2002 (12%) and high success during 2003 (80%), most likely related to the brown-tide bloom and nonbloom associated with these planting years. For both species restored, ecosystem function was becoming established by the end of the study, demonstrated by their ability to trap and bind fine particulate matter. We provide evidence from this study that seagrass restoration is a viable option for coastal managers and that once established, seagrasses can recover and expand.
In refractory masonry lining of industrial furnaces the compressibility of mortars is critical for the thermo-mechanical integrity of the structure. Compressive stress–strain behaviour of refractory ...mortars has been measured during drying at room temperature and in the service temperature range of 300–1400°C. The results have been explained using fractographic analysis and distinct element method computer modelling. The mortar failure has been shown to occur due to formation of shear bands of micro-cracks. The propagation of cracks preferably follows the shortest path between larger pores and is influenced by grain cohesion and interlocking. Tests with mortars featuring calcium aluminate cement, mono aluminium phosphate, water glass and bentonite clay binders have indicated that besides increasing the cohesion between the grains the binder reduces the internal friction that promotes higher compressibility. It has been found that the mortar with clay has the highest compressibility. The mortar with cement shows the most stable behaviour.
The temperature dependences of the magnetizations along the
a- and
b-axes of R
2Co
17 compounds (R = Nd, Pr, Ho and Dy) have been analyzed. By fitting the experimental curves of magnetizations ...measured on single crystals, precise values of the high order crystalline electric field (CEF) parameter
B
6
6 and of the coupling parameter
J
RT have been derived.
The temperature dependences of the magnetizations along the a- and b-axes of R sub 2 Co sub 17 compounds (R = Nd, Pr, Ho and Dy) have been analyzed. By fitting the experimental curves of ...magnetizations measured on single crystals, precise values of the high order crystalline electric field (CEF) parameter B sub 6 exp 6 and of the coupling parameter J sub RT have been derived.
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