The Use of Phase Diagrams in the Development and Use of Refractories

Reactions at the Interface Between Al2O3–SiO2 Ceramics with Additives of Alkaline-earth Oxides and Liquid Al–Si Alloy

“…Furthermore, these curves can be used to compare the chemical potential of the reactions for the different ceramics and hence explain why the alkaline earth oxides are considered as refractory additives for aluminosilicate ceramics. 7,8 This mechanism fairly agrees with the experimental results. Indeed, all the RZs consisted of Al 2 O 3 .…”

“…In particular, crucibles made of Al 2 O 3 , which secures remarkable chemical resistance, blended with SiO 2 , which lowers the sintering temperature, are widely used. [1][2][3][4][5][6][7][8] Further addition of oxides, such as MgO, CaO, and Cr 2 O 3 , can endow the ceramic with specific properties related to phase formation, sintering temperature, porosity, resistance to chemical attack or thermal shock, wettability, etc. 7,8 Extended porosity apparently facilitates liquid metal infiltration and, in the case interfacial reactions occur, accelerates ceramic aging.…”

“…[1][2][3][4][5][6][7][8] Further addition of oxides, such as MgO, CaO, and Cr 2 O 3 , can endow the ceramic with specific properties related to phase formation, sintering temperature, porosity, resistance to chemical attack or thermal shock, wettability, etc. 7,8 Extended porosity apparently facilitates liquid metal infiltration and, in the case interfacial reactions occur, accelerates ceramic aging. 9 Crystallinity greatly affects degradation rate, since glassy phases are usually more susceptible to corrosion than crystalline ones.…”

Mineralogy and technology of bricks used for the construction of the XII century ducal castle on the island of Ostrów Tumski, Wrocław (SW Poland)

“…According to Sağın and Böke (2013) a high temperature modification of silica could be formed at 800°C. In fact, the topology of the phase diagram of silica gives a higher value of 873°C when the beta-cristobalite is stable (Kraner, 1970). This high temperature silica form remains as a metastable form when the brick is cooled down from the baking temperature to the room temperature (Kraner, 1970).…”

“…In fact, the topology of the phase diagram of silica gives a higher value of 873°C when the beta-cristobalite is stable (Kraner, 1970). This high temperature silica form remains as a metastable form when the brick is cooled down from the baking temperature to the room temperature (Kraner, 1970). Bearing in mind those relationships, we might expect that bricks WZ1 and WZ21 were fired above 873°C.…”