The aim of this study is to determine the cyclic oxidation behavior of boron carbide (B 4 C) in the air atmosphere at elevated temperatures. For this purpose, as-received B 4 C powders were characterized by XRD and SEM and then shaped by the cold pressing method for oxidation studies. Tests were performed in the air atmosphere at 800˚C and 1000˚C for 5, 10, 15 and 20 hours. Oxidation behavior of the samples was evaluated by weight changes. XRD, SEM and EDS analyses were also conducted on the oxidized samples. It was observed that cyclic oxidation behaviors of the samples depended on temperature and time. Based on the analyses results and the microstructure observations, volatilization of B 2 O 3 had a significant effect on the oxidation of the samples as the temperature increased.
Coal ash is a residue that is created when coal is burned by power plants to produce electricity. Coal ash is one of the largest types of industrial waste and causes environmental pollution. On the other hand, coal ash is potentially a valuable source of minerals, including SiO2, Al2O3, CaO, MgO, Fe2O3, Na2O and K2O. This study aims to recycle the coal ash in production of low density masonry unit. Coal ash was characterized by chemical and X-ray diffraction analyses. The batches containing different ratios of coal ash and a brick making clay were prepared and shaped by cold pressing. The pressed samples were fired at 1050 and 1100• C. The physical properties such as water absorption, apparent porosity, linear shrinkage, and bulk density were determined. Microstructural observations were performed by using scanning electron microscopy. Based on the technological characteristics; it was observed that low density masonry units can be produced by using coal ash. This study supports the responsible recycling of coal ash by distinguishing beneficial use from disposal.
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