ceramics and clay products
TRANSCRIPT
Contents
• Ceramics (classification)
• Clay products employed in building industry.I. Tiles
II. Terracotta
III. Earthenware
IV. Stoneware
V. Porcelain
VI. Bricks
• Manufacturing process of common tiles.
• Types of common tiles used in building industries.
• Characteristics of good tiles
A ceramic is an inorganic, non-
metallic solid prepared by the action
of heat and subsequent cooling.
Ceramic materials may have a crystalline or
partly crystalline structure, or may
be amorphous (e.g., a glass).
Ceramics now include domestic, industrial and
building products and a wide range of ceramic
art.
The earliest ceramics
made by humans
were pottery objects,
made from clay,
either by itself or
mixed with other
materials, hardened
in fire. Later ceramics
were glazed and fired
to create a colored,
smooth surface.
A Ming Dynasty porcelain
vase dated to 1403–1424
They are hard and brittle
Strong in compression
Weak in shearing and tension
Withstands chemical erosion due to acidic or
caustic environments
Withstands high temperatures
These type of ceramics demonstrate
enhanced mechanical properties under
demanding conditions
Because they serve as structural
members,often being subjected to
mechanical loading,they are given the name
structural ceramics
A refractory material is one that can retain its
strength at high temperatures
They are used in linings for furnaces, kilns,
incinerators and reactors.
The oxides of aluminium, silicon and
magnesium are the most important materials
used in the manufacturing of refractories.
This is a class of products that includes
porcelain, china, pottery, stoneware and
vitreous tile.
They are white to off-white in appearance
and often contain a significant glossy or
vitreous component.
Imperviousness to fluids, low conductivity to
electricity, chemical inertness and an ability
to be formed into complex shapes are its
properties.
It is also known as engineering, advanced or
special ceramics.
It includes tiles used in space shuttles, missile
nose cones, ceramic disk brakes etc.
It can be classified into three material
categories.
Oxides- alumina, beryllia, ceria, zirconia
Non-oxides- carbide, bioride, nitride, silicide
Composite material- combination of oxides and
non-oxides.
These are not amenable to a great range of processing.
Methods for dealing with them tend to fall into one of two categories-
Either make the desired shape by reaction in situ, or
by forming powders into the desired shape, and then sintering to form a solid body.
Ceramic forming techniques include shaping by hand, slip casting, tape casting etc.
Non-crystalline ceramics, being glass tend to be formed from melts.The glass is shaped when in a state of toffee like viscosity.
Methods like blowing into a mould is used.
Later heat treatments cause this glass to become partly crystalline and this material is know as glass ceramic whhich is widely used for cooktops.
TERRACOTTAa type of earthenware , is a clay-based unglazed or glazed ceramic, where the fired body is porous.
Its uses include vessels (notably flower pots), water and waste water pipes, bricks, and surface embellishment in building construction, along with sculpture such as the Terracotta Army and Greek terracotta figurines.
The term is also used to refer to items made out of this material and to its natural, brownish orange color, which varies
- Fired clay
- Typically hollow, formed by pressing clay into a mould, byhollowing out portions of a solid, or by extruding it.
- Usually low-fired
- Typically a reddish, unglazed ceramic material. It may alsobe a hard-fired glazed or unglazed ceramic material.
- Durable (dependent upon the degree of firing)
- Fireproof
- Strong
Characteristics of Terra cotta
Types of Terra cotta:
Brownstone terra cotta
Fireproof construction terra cotta
Ceramic veneer terra cotta
Glazed architectural terra cotta
TYPICAL USESTypical historical uses for terra cotta included:
- Sculpture
- Unglazed units used for structural purposes
- Glazed units for building exteriors
STONEWAREStoneware is a vitreous or semi-vitreous ceramic made primarily from stoneware clay or non-refractory fire clay.
Stoneware is fired at high temperatures.
It is nonporous and so does not need a glaze
TYPES OF STONE WARETraditional stoneware
Fine stoneware
Chemical stoneware
Thermal shock resistant stoneware
Electrical stoneware
Traditional stoneware - a dense and inexpensive body. It is opaque, can be of any colour and breaks with a conchoidal or stony fracture. Traditionally made of fine-grained secondary, plastic clays which can used to shape very large pieces.
Fine stoneware - made from more carefully selected, prepared, and blended raw materials. It is used to produce tableware and art ware.
Chemical stoneware - used in the chemical industry, and when resistance to chemical attack is needed. Purer raw materials are used than for other stoneware bodies. Ali Baba is a popular name for a large chemical stoneware jars of up to 5,000 litres capacity used to store acids.
Thermal shock resistant stoneware – has additions of certain materials to enhance the thermal shock resistance of the fired body.
Electrical stoneware - historically used for electrical insulators, although it has been replaced by electrical porcelain.
TILES :A tile is a manufactured piece of hard-wearing material such as ceramic, stone, or even glass.
Tiles are generally used for covering roofs, floors, walls, showers, or other objects such as tabletops.
Historically, man has desired to create living spaces which were beautiful, durable, and user friendly. with that in mind, ceramic tile has been made by man for 4000 years.
Beautiful tiled surfaces have been found in the oldest pyramids, the ruins of Babylon, and ancient ruins of Greek cities.
Decorative tile work was invented in the near east,where it has enjoyed a longer popularity andassumed a greater variety of design than anywherein the world.
During the Islamic period, all methodsof tile decoration were brought to perfection in Persia.
ORIGIN
Painted and glazed tile of around 880 B.C,
Nimrud.
glazed bricks relief tile wall,from the palace of Persepolis
around 518 B.C. Iran
Glazed bricks relief tile wall,the Ishtar gate at Babylon,
around 575 B.C. ,Iraq.
Relief tile of the early 13th century,Afghanistan
Manufacture:
The raw materials used to create tiles are all found in the ground.
These raw materials, like clay is quarried and refined.
They are then mixed.
A dry mixture of clay, Magnesium silicate and other ingredients are pressed into a mould, and then fired at an extremely high temperature.
The ingredients used in this process are slightly wet.
They are forced through a nozzle, which forms the tile’s shape.
Other methods of creating tiles are slush mould and beehive kilns.
Types of Tiles:There are many types of tiles used for residential and commercial applications.
1. Roof tiles
2. Floor tiles
3. Pebble tiles
4. Ceiling tiles
5. Wall tiles
Roofing Tiles:
Roof tiles are designed mainly to keep out rain, and are traditionally made from locally available materials such as clay or slate.
Flat tiles - the simplest type, which are laid in regular overlapping
These are commonly made of ceramic or stone.
Recent technological advances have
resulted in rubber or glass tiles for floors as well.
Flooring tiles:
Pebble tiles:
Pebble Tiles is a composite material made up of marble pebbles or pieces of natural stone in different sizes, bound together with a transparent white or colored resin.
Ceiling tiles
Ceiling tiles are type of tiles used for covering ceilings of rooms.
Suspended ceilings
Acoustic Ceilings
Decorative Ceiling Tile
Wall Tiles:The concept behind using wall tiles is decorating the interior of a home without adding much stuff to the home.
Here are some places around the home that can benefit from tile applications.
COUNTER
BATHROOM
BACKSPLASH
FLOORING
WALL ACCENTS
EXTERIOR
Uses:
COUNTER
Ceramic tile is among the most common materials for kitchen countertops.
Because it's hard and water-resistant, it holds up extremely well to the moist and often humid environment of the kitchen.
BACKSPLASH :
Almost all backsplashes are made of tile because of its natural water resistance.
Some people prefer stone or marble, but these are expensive materials.
FLOORING :
Tile is one of the cheapest flooring options, especially compared to popular materials such as hardwood and marble.
Most tiles can withstand heavy use in living rooms and the heat and moisture of bathrooms.
WALL ACCENTS:
Small decorative tiles make great accents for walls, counters, and flooring.
They usually come in stronger, deeper colours and feature interesting patterns, often to complement the colour of bigger tiles.
EXTERIOR:Some tiles can actually be used on the exterior walls of your home.
These are usually decorative ones made to look like natural materials, such as wood and stone.
They make great alternatives to exterior painting, since they don't fade and can withstand most outdoor elements.
Earthenware is the term for pottery that has not been fired to the point of vitrification and is thus porous. Many types of pottery have been made from it from the earliest times. Until the 18th century it was the most common type of pottery outside the far East.
Earthenware is a type of clay that when fired to make pottery is soft and can be scratched with a knife. It is opaque and has an earthy or granular fracture. It is generally easier to shape on the wheel than porcelain. Due to its porosity earthenware must be glazed in order to be watertight.
Earthenware articles may be thick and heavy or as thin as bone china and porcelain, though they are not translucent and are more easily chipped. They are less strong than stoneware.
Earthenware may be biscuit (or
"bisque") fired to temperatures between 1000 and 1150 °C
(1800 and 2100 °F) and glost-
fired(or "glaze-fired")to between 950 to 1,050 °C (1,740 to
1,920 °F), the usual practice in
factories and some studio
potteries. Some studio potters
follow the reverse practice, with a
low-temperature bisque firing
and a high-temperature glost
firing.The firing temperature will
be determined by the raw
materials used and the desired
characteristics of the finished
ware.
After firing most earthenware bodies will be colored white, buff or red. For red earthenware, the firing temperature affects the color of the clay body. Lower temperatures produce a typical red terracotta colour; higher temperatures will make the clay brown or even black. Every clay has a temperature at which the body becomes weak and sags. Higher firing temperatures may cause earthenware to bloat.
Earthenware comprises "all primitive pottery whatever the colour, all terra-cottas, most building bricks, nearly all European pottery up to the seventeenth century, most of the wares of Egypt, Persia and the near East; Greek, Roman and Mediterranean, and some of the Chinese; and the fine earthenware which forms the greater part of our tableware today
Porcelain (also known as china or fine china) is a ceramic material made by heating materials, generally including clay in the form of kaolin, in a kiln to temperatures between 1,200 and 1,400 °C.
Porcelain can informally be referred to as "china" or "fine china.
Properties associated with porcelain include
low permeability
Elasticity
considerable strength
Hardness
Toughness
Whiteness
translucency
resonance
and a high resistance to chemical attack and thermal shock.
A brick is a block or a single unit of a kneaded clay-bearing soil, sand and lime, or concrete material, fire hardened or air dried, used inmasonry construction
Fired bricks are burned in a kiln which makes them durable. Modern, fired, clay bricks are formed in one of three processes – soft mud, dry press, or extruded.
Normally, brick contains the following ingredients:[16]
Silica (sand) – 50% to 60% by weight Alumina (clay) – 20% to 30% by weight Lime – 2 to 5% by weight Iron oxide – ≤ 7% by weight Magnesia – less than 1% by weight
materials
The composition of porcelain is highly variable, but the clay mineral kaolinite is often a raw material. Other raw materials can include feldspar, ball clay,glass, bone ash, steatite, quartz, petuntse and alabaster.
The clays used are often described as being long or short, depending on their plasticity.
Long clays are cohesive (sticky) and have high plasticity
short clays are less cohesive and have lower plasticity.
Porcelain can be divided into the three main categories:
hard-paste
soft-paste
bone china
(depending on the composition of the paste, the material used to form the body of a porcelain object and the firing conditions.)
Soft paste porcelain
It is to replicate Chinese porcelain by using mixtures of clay and ground-up glass (frit) to produce soft-paste porcelain. Soapstone and lime were known to have been included in these compositions.
Eg.
Hard paste porcelain
they were formed from a paste composed ofkaolin and alabaster and fired at temperatures up to 1,400 °C in a wood-fired kiln, producing a porcelain of great hardness, translucency, and strength.
Eg.
Bone china
bone china was made from two parts of bone-ash, one part of kaolin clay and one part china stone, although this has largely been replaced by feldspars from non-UK sources.
Bathroom fittings
Because of its durability, inability to rust and nonporous nature (porcelain has an absorption rate of less than .5%), glazed porcelain has been in use for personal hygiene .
porcelain chamber pots were commonly found in higher-class European households Porcelain toilet bowls, bidets and basins are still produced, though the tougher stoneware is more common.
However bath tubs are not made of porcelain, but often of so-called porcelain enamel on a metal base, usually of cast iron.
Dry pressed brick
The dry press method is similar to the soft mud brick method, but starts with a much thicker clay mix, so it forms more accurate, sharper-edged bricks. The greater force in pressing and the longer burn make this method more expensive.
Uses of brick
Bricks are used for building, block paving and pavement.
Bricks in the metallurgy and glass industries are often used for lining furnaces.
Raw materials
The main raw materials used in this process of making the tiles are:
1. clay minerals mined from the earth's crust
2. natural minerals such as feldspar that are used to lower the firing temperature
3. chemical additives required for the shaping process.
The raw materials must be pulverized and classified according to particle size.
The step by step process is as follows :
1. Mixing the ingredients:
2. Secondary crushing
3. Third particle size reduction
BatchingFor many ceramic products, including tile, the body composition is determined by the amount and type of raw materials. The raw materials also determine the color of the tile body, depending on the amount of iron-containing raw materials used. Batch calculations are thus required, which must take into consideration both physical properties and chemical compositions of the raw materials.
Once the ingredients are weighed, they are added together into a shell mixer, ribbon mixer, or intensive mixer. A shell mixer consists of two cylinders joined into a V, which rotates to tumble and mix the material. A ribbon mixer uses helical vanes, and an intensive mixer uses rapidly revolving plows.
Sometimes it is necessary to add water to improve the mixing of a multiple-ingredient batch as well as to achieve fine grinding. This process is called wet milling and is often performed using a ball mill. The resulting water-filled mixture is called a slurry or slip.
Mixing and grinding
Spray drying
If wet milling is first used, the excess water is usually removed via spray drying. This involves pumping the slurry to an atomizer consisting of a rapidly rotating disk or nozzle. Droplets of the slip are dried as they are heated by a rising hot air column, forming small, free flowing granules that result in a powder suitable for forming.
Most tile is formed by dry pressing.
– In this method, the free flowing powder—containing organic binder or a low percentage of moisture—flows from a hopper into the forming die.
– The material is compressed in a steel cavity by steel plungers and is then ejected by the bottom plunger.
– Automated presses are used with operating pressures as high as 2,500 tons.
– Extrusion plus punching is used to produce irregularly shaped tile and thinner tile faster and more economically.
– This involves compacting a plastic mass in a high-pressure cylinder and forcing the material to flow out of the cylinder into short slugs. These slugs are then punched into one or more tiles using hydraulic or pneumatic punching presses.
– Ram pressing is often used for heavily profiled tiles.
• With this method, extruded slugs of the tile body are pressed between two halves of a hard or porous mold mounted in a hydraulic press.
• The formed part is removed by first applying vacuum to the top half of the mold to free the part from the bottom half, followed by forcing air through the top half to free the top part.
• Excess material must be removed from the part and additional finishing may be needed.Another process, called pressure glazing, has recently been developed. This process combines glazing and shaping simultaneously by pressing the glaze (in spray-dried powder form) directly in the die filled with the tile body powder. Advantages include the elimination of glazing lines, as well as the glazing waste material (calledsludge) that is produced with the conventional method.
Ceramic tile usually must be dried (at high relative humidity) after forming, especially if a wet method is used. Drying, which can take several days, removes the water at a slow enough rate to prevent shrinkage cracks. Continuous or tunnel driers are used that are heated using gas or oil, infrared lamps, or microwave energy. Infrared drying is better suited for thin tile, whereas microwave drying works better for thicker tile. Another method, impulse drying, uses pulses of hot air flowing in the transverse direction instead of continuously in the material flow direction.
Glazing
After a batch formulation is calculated, the raw materials are weighed, mixed and dry or wet milled. In centrifugal glazing or discing, the glaze is fed through a rotating disc that flings or throws the glaze onto the tile. In the bell/waterfall method, a stream of glaze falls onto the tile as it passes on a conveyor underneath. Sometimes, the glaze is simply sprayed on. For multiple glaze applications, screen printing on, under, or between tile that have been wet glazed is used. In this process, glaze is forced through a screen by a rubber squeegee or other device. Dry glazing is also being used. This involves the application of powders, crushed frits (glass materials), and granulated glazes onto a wet-glazed tile surface. After firing, the glaze particles melt into each other to produce a surface like granite.
FiringAfter glazing, the tile must be heated intensely to strengthen it and
give it the desired porosity. Two types of ovens, orAfter forming, the file is dried slowly (for several days) and at high humidity, to prevent cracking and shrinkage. Next, the glaze is applied, and then the tile is fired in a furnace or kiln. Although some types of tile require a two-step firing process, wet-milled tile is fired only once, at temperatures of 2,000 degrees Fahrenheit or more. Wall tile, or tile that is prepared by dry grinding instead of wet milling (see #2 and #3 above), usually requires a two-step process. In this process, the tile goes through a low-temperature firing called bisque firing before glazing. This step removes the volatiles from the material and most or all of the shrinkage. The body and glaze are then fired together in a process called glost firing. Both firing processes take place in a tunnel or continuous kiln, which consists of a chamber through which the ware is slowly moved on a conveyor on refractory batts—shelves built of materials that are resistant to high temperatures—or in containers called saggers.
TILES• There are several types of tiles used for residential and
commercial applications.
• Tiles provide one of the most cost-effective and environmentally friendly flooring choices.
• Tiles are made from natural clay and often from other (recycled) materials.
• Tile manufacturing does not necessitate the use of heavy chemicals or other harmful substances used to make other flooring types. There are no trees to be cut down as with hardwood floors, and the best part is that tiles are durable and have a long lifespan.
COMMON TYPES OF TILES
CERAMIC ( QUARRY UNGLAZED, PORCELAIN, TILE MOSAICS, MARBLE )NATURAL STONE TILES (GRANITE,SLATE, TRAVERTINE,MARBLE,ONYX,SANDSTONE)
CERAMIC TILES
• Ceramic tile comes in two forms: glazed and unglazed.
• Unglazed tile is referred to as quarry tile. Ceramic tiles are made from clay and then heated.
QUARRY ( UNGLAZED)
TILE• Inexpensive, durable
and natural option for industrial, commercial and residential tile applications.
• Quarry tile is used a lot in industrial settings because it is so durable and can also be used outdoors.
• It has some other great qualities as well, such as being less prone to chips and scratches. In colder climates, freeze-resistant grades of quarry tile are used to prevent any weather-related problems.
• Like almost all tile types, quarry is porous, which means that it can become stained
• The difference between porcelain and ceramic is that porcelain is fired at a higher temperature, making it more dense and moisture-resistant.
• Porcelain tiles are also less porous, making them more stain-resistant.
• For these reasons, most porcelain tiles are suitable for both indoor and outdoor installations.
• Porcelain tiles are hard to cut due to their density and hardness, so the cost and labor involved is often higher.
• Porcelain tiles are available in matte, unglazed or a high-polished finish. In recent years, the prices have become closer to those of ceramic tile.
• Mosaics are most commonly used for smaller areas, such as a bathroom or kitchen backsplash, or even small counter space areas. Mosaic tiles are usually less than six square inches and made of porcelain or clay composition. Many come in squares, octagons, hexagons or other unique shapes. The tiles are also available in pre-mounted paper or fabric mesh sheets.
• Marble is a versatile natural stone which has been used for centuries in homes to create a luxurious and unique look.
• Because marble is a natural stone, there are variations in the color of each tile. Many homeowners like this, as it creates a unique, one-of-a-kind design, while others prefer a more consistent look, like ceramic tile.
• Marble is porous and must be sealed just like all other tile types.
NATURAL TILES
• Natural Stone Tiles There are several types of natural stone tiles which are used for flooring, walls and more. These include:1. Granite
2. Slate
3. Travertine
4. Onyx
5. Sandstone
6. Marble
• Granite tiles are naturally antibacterial and aren’t damaged by water contact ,this is why they are such a great choice for kitchen and bathroom applications.
• Granite – Granite has been used for countertops for years, and it is also used for shower walls and bathroom counters
SLATE
• Slate is a fine-grained, rock derived from an original shale-type sedimentary rock composed of clay or volcanic ash through low-grade regional metamorphism.
• Slate tiles are growing in popularity due to their versatility. They are even used as roofing shingles.
• Slate is a natural material and is available in several color ranges, from gray to purple to black.
• Slate is used outside as well as inside because of its natural look and range of colors.
• Travertine is a form of limestone deposited by mineral springs, especially hot springs. Travertine often has a fibrous or concentric appearance and exists in white, tan, cream-colored, and even rusty varieties
• Travertine – Travertine is natural beige stone and is used for bathroom flooring, kitchen backsplashes, shower mosaics and more.
ONYX
• Onyx is a banded variety of chalcedony. The colors of its bands range from white to almost every color (save some shades, such as purple or blue)
• Onyx – Onyx is well known for its creamy, pearl-like look.
• Onyx is not a common choice for flooring, but it is used on some occasions.
• It is used more frequently for skirting around bathtubs and mosaics.
SANDSTONE
• A sedimentary rock formed of sand-sized grains that have been either compacted or cemented together.
• Sandstone is extremely durable, has a grainy look and feel
• It is often used for wall applications.
• Marble is a versatile natural stone which has been used for centuries in homes to create a luxurious and unique look.
• Because marble is a natural stone, there are variations in the color of each tile. Many homeowners like this, as it creates a unique, one-of-a-kind design, while others prefer a more consistent look, like ceramic tile.
• Marble is porous and must be sealed just like all other tile types.
• this is the basic parameter which determines the choice of a
floor tile for the given premise. It specifies the resistance of
the tile to mechanical damage resulting from the impact of
the abrasive factor. The greater the hardness of the tile is,
the lower its susceptibility to scratching, wear and tear
during walking and abrasions etc.
• The resistance to abrasion consists in the specification of
the number of rotations of the device that rubs the surface
of the glazed tile after which the permanent traces of
abrasion become visible
Water Absorption• Properly installed and grouted, ceramic tiles are
an excellent choice for use in wet areas. But while the glaze of ceramic tiles is nonporous, a glaze tile may absorb water through its body. Any glazed or unglazed ceramic tile that absorbs more than 3% moisture is unsuitable for outdoor usage in climates where freezing conditions may occur.
FREEZE-RESISTANCE
• Freeze resistance is directly relevant to water
absorption in ceramic tiles. The less water a
ceramic tile absorbs, the greater its frost
resistance. Exterior applications require highly
frost resistant tiles. Often, porcelain tiles
become the material of choice for such
conditions.
Fire Resistance
• Due to a noncombustible composition, ceramic tiles are completely fireproof at any temperature.
• They work especially well around open flames, hot objects (crockery, barbecues, etc.
• A ceramic tile surface will not alter, nor will they produce any toxic gases, smoke or fumes during a fire.
• Ceramic tiles will not burn or feed to a fire in any way.
• They also act as a protection for structural surfaces.
Mechanical characteristics
Resistance to loads, such as the weight
of people and furniture to which floor
tiles may be subjected and which they
should be able to bear without suffering
damage. The tiles are tested for these
mechanical characteristics: resistance to
bending and bending breaking load.
RESISTANCE TO LOADS
The loads usually vary from heavy cots and fridges in household tiles and heavy vehicles in garage etc.
Chemical characteristics
• Resistance to the corrosive or staining action
of substances that may come into contact
with the tile surface.
• These chemical characteristics are tested:
– Resistance to staining,
– Resistance to household chemicals, and
– Resistance to acids and alkaline.
Many tiles are prone to rust and
bleach when they come in contact
with certain chemicals or remain in
contact with water for too long.
Safety characteristics
The parameter used for slip resistance is called the Coefficient of Friction (COF). The higher the COF, the better the slip resistance of the tiles. Unglazed tiles, mosaic tiles and rough surfaced tiles are less slippery when compared with smooth and glossy glazed tiles. Therefore, these are recommended to be used in industrial, kitchen, bathroom floor and swimming pool areas.
SLIP RESISTANT TILES
The groves provide more friction and these type of tiles are used for pavements and verandas.
STAIN RESISTANCE
• Tile that are stain resistant are hygienic and
easily cleaned. Glazed ceramic tiles resist
stains because of their glazed surface.
Porcelain tiles are made stain resistant
because of their compactness or low water
absorption characteristics.