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IMPORTANCE OF FIRED BOND IN DETERMINING THE PORE QUALITIES OF STRUCTURAL…
IMPORTANCE OF FIRED BOND IN DETERMINING THE PORE QUALITIES OF STRUCTURAL CLAY PRODUCTS
The
rigidity and strength
of a ceramic part are obtained during
firing
During heating, the clay dehydrates and eliminate the hydrating water where
vitrification and melting begins
.
Vitrification is defined as the
gradual formation of a liquid glass
that flows into and
fills some
of the
pore volume
. In ceramics, it gives
impermeability of water
.
This fired bond between the particulate constituents may result from
partial fusion
of some of the constituents and followed by
cooling
to develop a
glassy bond
.
When structural clay products are fired, atomic bonding between particles (
fired bond
) is
developed by a diffusion mechanism
. The particles of the molten substance will diffuse into each other. This fused phase
flows around
the remaining
unmelted particles and fill in the pores
as a results of surface tension force or capillary motion. The
pores
between the particles will
reduce
.
Upon
cooling
, this fused phase forms a glassy matrix that results in a
dense
,
strong
body with signiicant
shrinkage
. Also, the
porosity and water absorption
of structural clay products will
decrease
.
IMPORTANCE PROPERTIES THAT SHOULD CONSIDER IN FABRICATING FACING MATERIALS
(
FACE BRICKS
)
COLOUR
different iron used in facing materials will give different colours
this colour can be determine during preparing the raw materials
the colour of product based on the formulation used
example colours : red velvet, greyish
TEXTURE
important to make sure it can be hold or stick the bricks (or any other material) to the surface
Coatings
to protect the surface (to keep the colour and texture from changing/stay the same like the original looks)
DURABILITY
depends on the subject's application
depends/based on loads that will be put on the materials
are the materials can absorb certain compressive loads? or bear the high temperature on it?
EFFLORESCENCE
the white spots on the bricks after exposed to humidity or hot temperature for a long time
MOISTURE EXPANSION
related to heat
to avoid the facing materials from moving or change (which will cause any accident or changes towards the materials or product properties)
SIZE TOLERANCE AND CHIPPING
might happened during exportation from the store
when the facing materials collide or bump into each other
size tolerance occurs after firing
can be seen by physical observation