In the first part of the thesis, we described the fiberizing centrifuge, the fiberizing wheel and fiberizing process for the production of mineral glass wool. We have described
cobalt, bismuth and the cobalt superalloy Stellite21. We have also described how increased concentrations of bismuth occur in the alloy used for fiberizing wheels. We have explained what trace elements are and why they have an important influence on the mechanical properties of alloys. We also described the corrosion resistance process in contact with molten glass, which is carried out according to Knauf Insulation's internal standard.
We have discussed the cobalt superalloy Stellite21 and the influence of bismuth on its mechanical properties. A very low concentration of bismuth was added to Stellite21, and test bars were produced. The test bars were used to produce samples to test different mechanical properties. We carried out a tensile strength test, an impact toughness test, a hardness test, a creep resistance test and a molten glass corrosion resistance test. Microstructural analysis was also carried out using optical and scanning electron microscopes.
The results of the mechanical properties tests and microstructural analysis of the Stellite21 alloy with bismuth addition were compared with those of Stellite21.
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