"The permanent mold process is one of the major casting processes, using metal molds to give high strength castings due to rapid solidification. Ceramic coatings on the mold surfaces are used to achieve the desired solidification rate of the casting, to minimize thermal shock and failure of the mold, and to facilitate release of the casting from the mold. Because the ceramic coatings have an important effect on the thermal behavior and thermal fatigue resistance of the permanent molds, knowledge of the thermal conductivity of the coating is essential for any modeling of the system.
In this research, a survey of experimental methods for measuring thermal conductivity was conducted and the longitudinal transient method was selected as the best choice for simulating actual conditions in a permanent mold casting process. A steel bar is coated with the ceramic and dipped into molten aluminum at 700C; the temperature gradients are measured using a data acquisition system connected to a computer. From the acquired data, the thermal conductivity of the steel/coating system, the steel, and the coating can be determined.
The thermal conductivity of an insulating-type mold coating was determined to test this technique. The thermal conductivity measurements from uncoated steel samples were very close to those reported in the literature for the steel. The thermal conductivity of the mold coating -- 0.027 W/cm C -- was close to that calculated based on the properties of the constituents in the coating. The influence of the coating on insulation characteristics was also measured from the tests"--Abstract, pages iii-iv.
Askeland, Donald R.
Ramsay, Christopher W.
Materials Science and Engineering
M.S. in Metallurgical Engineering
University of Missouri--Rolla
xiv, 87 pages
© 1994 Mohammad Reza Banki, All rights reserved.
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Banki, Mohammad Reza, "Measurement of thermal conductivity of permanent mold ceramic coatings" (1994). Masters Theses. 1381.