| Effect of Water/Plaster Ratio on Preparing Molds for Slip
Casting of Sanitaryware; Rheology of the Initial Plaster
Slurry, Microstructure and Mold Properties |
Rafael E. Ochoa,a, * Carlos A. Gutiérrez,a Jorge López-Cuevas,a Juan Rendón,a
José Luis Rodríguez-Galiciaa and J. Cruz-Álvarezb
Pages : 84-89
DOI : 10.1080/0371750X.2018.1475262 |
| Abstract |
| In the common industrial range of water/plaster ratio to make plaster molds for slip
casting of sanitaryware (from 66 to 82 parts of water/100 parts of plaster by weight),
rheology of the initial plaster slurry, and microstructure and final properties of the
mold and cast body were evaluated. Working time or time suitable for pouring plaster
slurry to make the molds with lowest probability of defects (before an abrupt increase
in viscosity due to the formation of gypsum crystals), such as pin holes and incomplete
filling of cavities because of poor flow behavior, was determined through viscosity
curves as a function of time. At the highest water/plaster ratio, the optimum working
time for making the plaster molds was found. As the water/plaster ratio was increased,
morphology of the gypsum crystals was modified towards large needles, promoting
an increase in the mold porosity (up to 11%) that enhanced the main property of the
plaster mold, i.e. casting rate (up to 8%), without changing the properties of the cast
body and with a slight reduction in compressive strength of the mold (1.5%).
[Keywords: Water/plaster ratio, Plaster mold, Slip casting, Sanitaryware] |
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