Reinforcement of rice husk in ceramic shell mould system for investment casting process
Generally, production of metal component via investment casting process need a development of a very thin ceramic shell mould that can withstand a higher molten metal temperature. Development of ceramic shell mould is very crucial as its involves several times of dipping process followed by the d...
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| Main Author: | |
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| Format: | Thesis |
| Language: | English English English |
| Published: |
2012
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| Subjects: | |
| Online Access: | http://eprints.uthm.edu.my/2002/1/24p%20NOOR%20HASLIZA%20KAMARUDIN.pdf http://eprints.uthm.edu.my/2002/2/NOOR%20HASLIZA%20KAMARUDIN%20COPYRIGHT%20DECLARATION.pdf http://eprints.uthm.edu.my/2002/3/NOOR%20HASLIZA%20KAMARUDIN%20WATERMARK.pdf |
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| Summary: | Generally, production of metal component via investment casting process need a
development of a very thin ceramic shell mould that can withstand a higher molten
metal temperature. Development of ceramic shell mould is very crucial as its
involves several times of dipping process followed by the drying and firing stages.
Typically, this ceramic shell mould is very brittle and easily prone to cracks that will
lead to the casting defects and handling problem at early stage. Therefore, this work
focuses on the development of brittle ceramic shell mould via reinforcement method.
Rice husk fibers and rice husk ash were selected as a reinforcement material due to
the facts that its contains higher percentage of silica. The samples were prepared by
three compositions which are untreated rice husk fiber, rice husk treated fiber by
sodium hydroxide and rice husk ash. The mechanical and physical properties of
ceramic shell mould layering system were measured via Modulus of Rupture, density
and porosity, permeability, shrinkage, thermal expansion and observation of metal
casting. Experimental results show that the reinforced ceramic shell mould with
treated rice husk fiber achieved highest green strength (1.34 MPa). However,
ceramic shell mould with rice husk ash shows the highest fired strength (4.87 MPa).
Indeed, rice husk fibers additions have greatly increased porosity after firing at 1000
ºC by values of 20.06 % and hence promotes increments of permeability by value of
2.46 x 10
-11
2
cm
. The present of silica also gives highest density, lowest shrinkage
and thermal expansion by value of 1.9516 g/cm
3
, 0.1258 mm and 0.088 %
respectively for ceramic shell with rice husk ash. Observation of metal casting shows
that reinforced ceramic shell can withstand high molten metal temperature without
cracking. Hence, reinforced ceramic shell has reduced production time and cost via
avoiding failure to the mould and end cast product. |
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