1. Corresponding author: mfon obot @yahoo.com, obadavid4@gmail.com
PRODUCTION OF CERAMIC FLOOR TILES BY SOLID SLIP CASTING AND DRY PRESSING METHOD
1Obot M. U, 2Peter-Udoaka I, 3Nathan I. U, 4Ohanwe C. E, 5Obada, D. O 6Omiogbemi, I.M.B and 7Balogun M.B
1,5,6,7 Department of Mechanical Engineering, Ahmadu Bello University Zaria
2,3,4 Department of Metallurgical/Material Engineering, Federal University of Tech, Owerri
Corresponding author: mfon
ABSTRACT
Introduction
Ceramic floor tiles were produced with the slip casting and dry pressing method. The bodies of the tiles were prepared with Nsu Clay, Flint and Feldspar. Tests were carried out on the slip cast and dry press tile samples to determine their physical and mechanical properties such as; apparent porosity, bulk density, linear shrinkage, and modulus of rupture. The average apparent porosity value for slip cast samples was 15.73% while that for dry pressed sample was 24.97%. Also, the average bulk densities were 2.18g/cm3 and 2.33g/cm3 for the slip cast and dry pressed samples respectively. The average result for linear shrinkage gave 8.44% and 6.11% for the slip cast and dry pressed tiles respectively. It was observed that it is easier to obtain dimensional control for the dry pressed tile, as compared to the slip cast tile. Finally, the average modulus of rupture for the slip cast and dry pressed tile samples was and Kgf/cm2 respectively.
Ceramics are hard brittle materials that are produced by high temperature firing of inorganic, nonmetallic minerals or rock into a desire shape. Ceramic is the science of manufacturing prepared from pliable, earthy materials that are rigid by exposure to heat. As early as about 24,000 BC, animal and human figurines were made in settlements around Egypt, China, India and Mesopotamia, from clay and other materials dug from the ground and fired in kilns. Clay as a product of disintegration from chemical weathering of feldspathic rock is a viable mineral that exhibit high economic significance and usefulness that affects every spheres of life. It consists of fine particles of hydrous aluminum silicate which has a wide variety of physical characteristic such as plasticity, shrinkage under firing and under air-drying, fineness of grain, colour after firing, Hardness cohesion and capacity of the surface to take decoration. Clay is a common name for a number of fine-grained, earthy materials that become plastic and tenacious when moist, and that becomes permanently hard when baked or fired. Thus, clay can be shaped while wet and soft, and then fired to obtain ceramic product. Economics means of production of tiles from locally available raw materials, rapid growth of the local building industries and cost of crystalline served as motivation of this research.
Aim and Objectives
Aim of the Research
This research aim at determining from the results of two carefully controlled ceramic floor tiles production methods, which of them has a better set of properties, and hence acknowledging its production method.
Objectives of the Research
Production of ceramic floor tiles by solid slip casting and dry pressing methods.
Examining the physical and mechanical properties of the produced tiles.
Materials
Methods
Determination of the recipe of the floor tile.
Nsu clay powder, feldspar and flint powder was collected. The recipe for floor tiles was determined from the triaxial diagram of feldspar, clay and flint (silica) showing areas of commercial wares. Floor tile recipe was determined to be 35% clay, 55% feldspar and 10% flint. To obtain 2000g of ceramic body for floor tile recipe, 700g of Nsu clay was measured out, 200g of flint and 1100g of feldspar were measured out using the scale, and emptied into a clean and dry basin. The powdery mixture was properly mixed manually, and then it was sieved using a mesh size of 425μm.
Production of Floor tiles using Slip Casting Method
The POP mould was opened up and the surfaces of the cope and drag were cleaned using a brush. Talc powder was sprinkled and rubbed in the internal walls of the cavities.
The mould was closed and tightened with a twine. Four plastic funnels were placed into the orifice of the cope, which served as risers for the slip.
The deflocculated ceramic slip was then carefully poured into the POP mould cavity through the funnels and allowed to set for a period of 24 hours in the POP mould.
Afterwards the cope is lifted up to remove the set samples which is then glazed and fired in the oven to 1200oC
Production of Floor tiles using Dry Pressing Method
300cm3 of water measured using the volumetric cylinder was added into the mixture, and mixed in the basin. The mixing was done until the workability stage of the ceramic body was attained.
A quantity of the ceramic body was put into the metal mould and placed upon the mantel piece of a hydraulic pressing machine. The die was placed over the mould, and a minimal compressive force of 250 KN was applied upon the sample in the die. The compacted tile was then dried in an electric dryer at 100oC for 48 hours to remove the water content.
The surface of tiles to be glazed was dipped into a glaze solution with a recipe given as 50% feldspar, 21% flint, 15% whitening, 7% Nsu clay, 7% Borax and 7% Zinc oxide. The compacted tile was dried in a drier again for 24 hours to remove the water content in the glaze. The glazed tile was then fired in the furnace up to 1200oC, for 24 hours.
Produced Tiles
Plate1: POP cope and drag (showing tile cavities)
Fig 2: Die pressed (top row) and slip casted tiles (bottom row
Results
Conclusions
It is seen that increase in shrinkage and apparent density results in a decrease in apparent porosity.
Conversely, an increase in apparent porosity and percentage water absorption gives a decrease in modulus of rupture. Therefore tiles produced through solid slip casting have a lower value of apparent porosity and percentage water absorption and show a higher resistance to rupture (i.e. higher MOR) than tiles produced through dry pressing with higher value of apparent porosity and percentage water absorption.
Those out of the two methods of producing floor tiles, slip cast process produces advantageous properties for ceramic floor tiles of low porosity and water absorption, high apparent density and modulus of rupture.
Dry pressed method gives advantages of obtaining a dimensional control for tiles production than slip cast method due to low shrinkage observed in the dry pressed tiles
Fig 1: Comparison of properties of slip casted and dry pressed tile
Fig 2: Comparison of densities of slip casted and dry pressed tile
Fig 3: Comparison of green and fired strength of slip casted and dry pressed tile