PRACTICAL ENGLISH IN CERAMICS

PRACTICAL ENGLISH IN CERAMICS

• Ceramika ---- Ceramics

• Ceramika specjalna – Special ceramics

• Ceramika ogniotrwała – Refractory materials

• Szkło - Glass

• Szkliwa i emalie - Glazes and enamels

• Szkło-ceramika - Glass - ceramics

• Materiały wiążące - Binding materials

• Cienkie warstwy - Coatings

• Biomateriały - Biomaterials

Programm:

Non-metalic inorganic materials

1. Characteristic of ceramic materials

– Sintered (classic ceramics) – Melted (glasses and glazes)

– Binding (lime, gypsum, cement, mortars binding )

2. Sintered ceramics – classic and advanced 3. Glasses and glass-ceramics

4. Special glasses and method of their production (sol/gel method)

5. Bioactive glasses and glass-ceramics materials 6. Amorphous coatings on glassy base

7. Binding materials

CREDIT CONDITIONS OF COURSE

• Presence in lectures

• Preparation of the seminar paper

References to the subject:

• Draft of lectures

• „Applied Ceramic Technology” vol. I and II;

SACMI

My motto

• Not the most important presence at lectures!!!!

• Most important is - something to understand, learn, remember

!!!

What does „ceramics”

mean?????

Ceramics derives from Greek word Keramos; this is the product

formed by the action of fire (sintering)

Now (unambiguous definition : Non-metalic, inorganic products

obtained by the transformation of mineral or chemical raw materials

during high-temperature process

How can we divide ceramics?

•SINTERED PRODUCTS (classic ceramics)

•MELTED PRODUCTS (glasses)

•BINDING MATERIALS (lime, gypsum, cement)

SINTERED MATERIALS

Examples:

• Porcelain tableware

• Building ceramics – brick, slate, various tiles: floor and wall

• Sanitary ware

• Advanced ceramics

SINTERED MATERIALS

Kind of tiles:

Floor and wall

Wall tiles: double and single fired;

• Classification on the base of forming method

• Technical features: porosity between 13-18%

• Glazes are usually used Floor tiles:

• Vitrified single fired tiles („gres”)-compact mass

• Porcelain tiles, usually glazed

MELTED MATERIALS (GLASSES)

• Soda-lima-silica glasses (building, automotive, packaging, tableware)

• Optical glasses

• Technical glasses

• Crystal glasses

• Bio-glasses

BINDING MATERIALS

• Lime (CaO from CaCO₃))

• Gypsum (CaSO₄)

• Cement (cement clinker +

gypsum + mineral additions – ashes)

Basic differences between particular groups of materials

• These differences concern:

- production process

-structure, microstructure and material properties

-application

DIFFERENCES - PROCESS

SINTERED MATERIALS

Raw materials preparation

Preparation of ceramic body Formation ceramic body

Drying and sintering

SINTERED CERAMICS

Raw materials:

• Plastic: clay minerals - kaolinite

Al₄[Si₄O₁₀](OH)₈ , illite Al₂(Si₅O₁₀)(OH)₂ montmorillonite;

• Non-plastic: silica SiO₂ (to do smaller

body contraction) , feldspars X₄(Al₄Si₄O₁₆) X – K, Na (fluxing agents)

Kaolinite structure

• Basic element of kaolinite:

• - silica-oxygen sheet („tetrahedral sheet”)

• - alumina-oxygen-hydroxyl sheet („octahedral sheet”)

---

• L.K. Si = 4___________________________

[SiO2O5 ]-2

• ___________________________ H2O

• L.K. Al = 6___________________________

[AlO6]-9

Kaolinite spatial structure

DIFFERENCES - PROCESS

MELTED PRODUCTS (GLASSES) Raw materias preparation

Melting

Forming from the melt

Vitrification

GLASSES

Raw materials:

• Glass-forming compounds (high

viscosity at melting temperature):

SiO₂; B₂O₃, P₂O_5;

• Fluxing agents: carbonates of

alkaline element – Na₂CO₃; K₂CO₃; Li₂CO₃

• Modifieres – PbO, BaO, ZnO

BINDING MATERIALS

Materials in the form of powders;

Lack of product formation;

 They are able to bind after water addition

BINDING MATERIALS

Raw materials:

Limestone, marl, clays  clinker Clinker compounds: silicates and

aluminates

DIFFERENCES:

STRUCTURE AND PROPERTIES

Ceramics: Poly-crystalline products; can contain amorphous phase; produced from mineral raw materials by firing; products are not-

translucent or translucent (porcelain)

Glasses: amorphous products; no long-range

ordering of structure; products are transparent Binding materials: poly-crystalline products in

the form of powders

CERAMIC PRODUCT CLASIFICATION

• Criteria:

- Physical features (colour, porous structure, optical properties)

- Production technology ( method of formation; double or single

firing; use or not glazes) - Application

CERAMIC PRODUCT CLASIFICATION Physical features

Porosity:

Compact or porous structure (porosity 3- 12%) – dependent on formation method and firing temperature)

Color:

White or red after firing (dependent on the content of iron in raw materials)

Porous products

Coloured (red) after firing

brick

 refractory

pottery

White after firing

faience

Some

products of advanced

ceramics

NON-POROUS PRODUCTS

Not-translucent:

• Stoneware;

• Semi-vitreous

Translucent, white

• Porceain

Low-translucent products (yellow)

• Steatite products

• Advanced products for the electronic

CERAMIC PRODUCT CLASIFICATION Production technology

Formation:

• castings,

• plastic extrusion

• pressing

PRODUCTION PROCESS

SINTERED MATERIALS

Raw materials preparation

Preparation of ceramic body Formation from ceramic body

Drying and sintering

SINTERED CERAMICS

Raw materials:

• Plastic: clay minerals - kaolinite Al₄[Si₄O₁₀] (OH)8 , illite Al₂(Si₅O₁₀)(OH)₂ montmorillonite;

• Non-plastic: silica SiO₂ (to do smaller body

contraction -shrinkage) , feldspars X₄(Al₄Si₄O₁₆) X – K, Na (fluxing agents)

• Helpful raw materials

Clays

(illite-chlorite,

illite-kaolinitic types)

Kaolins

Bentonites

Shale rocks

•Mineralogical characterisation:

sedimentary rocks composed of various types of silicate minerals, mostly hydrarted aluminum silicates (Al2O3mSiO2nH2O).

Plastic raw materials

Plastic raw materials

•Basic feature of clays:

PLASTICITY– ability, after introducing of water, formation of mass, which can be shaped by various methods, and

obtained shape is preserved during and after drying and firing

COMPLEMENTARY RAW MATERIAL

Role in production process

- to reduce shrinkage during drying and firing of plastic raw materials

•Silica raw materials(SiO₂):

Quartz, qartzites, quartz sands

•Raw materials of high content of alumina Al₂O₃

Aluminum raw materials: alumina, aluminum hydroxides;

aluminum, synthetic materials (corundum)^;

Aluminum-silicate raw materials: : sillimanite, mullite

COMPLEMENTARY RAW MATERIAL

Role in production process

Fluxes; decreasing sintering and melting temperatures!

•Feldspars:

 Potasium feldspar (ortoklaz) K₂O Al2O3 SiO2;

 Sodium feldspar (albit) Na₂O Al₂O₃ SiO₂;

 Calcium feldspar (anortyt) CaO Al2O3 SiO2

•Carbonates of calcium and magnezium (Ca, Mg):

 Calcium carbonateCaCO₃;

 Magnesium carbonate MgCO3;

 Double calcium/magnesium carbonate CaCO₃ MgCO₃;

Clays classification

as the raw materials for ceramics production:

• Content of impurities in the form of iron compounds (it affects on the product color after firing

• Content of impurities in the form of calcium, magnesium, potasium, sodium compounds playing the

role of fluxing agents (this

determines the fire resistance)

Examples:

• Kaolin and clays (ball clays, china clays) – firing in white or cream (low content of iron compounds) they are used to porcelain and faience production

• Clays for brick production (marl-carbonate clay, vitrifiable clay); after firing they take on beige-orange color due to present of

ferrous minerals;

• Refractory clays (Kaolin-type china-clays) , low content of fluxing agents (less than 6%), give a product with a high fire resistance

Sintered products

• Raw materials preparation

• Preparation of ceramic body

• Shaping of ceramic body (ambient conditions)

• Drying and sintering (firing) – high- temperature process

Raw materials and ceramic body

preparation

Raw materials preparation:

• Enrichment (removal of not-profitable components)

• Pre-processing - (crushing)

Compilation of ceramic body; Examples:

faience:

clays: medium-plastic 30%

very plastic 32%

marble or chalk (CaCO₃) 12%

quartz sands 26%

porcelain

Clays – kaolin type 50%

(Ball-clays, china clays)

Feldspar 25%

Quartz 25%

Body compilation- wall tiles

Ceramic body preparation

Removal of water and air from mass using special filter or

vacuum press

Vacuum press

Ceramic body fate

What is the fate of body ?

content of H₂O in %

Casting 25-35

Plastic extrusion 15-25

Plastic pressing 10-14

Dry pressing 3-9

Shaping of body

Casting in gypsum form

Formation from plastic mass –hand

made, extrusion, formation on press

Pressing

Dry and semi-dry mass

Plastic mass

Thermo-plastic formation

Casting in gypsum form

Preparation of slip body

- water suspension of ground raw ceramic – low viscosity, low sedimentation rate, low shrinkage

(addition of fluidization agents : sodium silicates – „water” glass)

Casting

Casting of slip body in gypsum form

Body is left in gypsum form up to body

densification (water is removed from body by gypsum form absorption)

Plastic body formation

Hand made:

•Various type

of clay body modeling

Turning of ceramics:

The oldest way of formation:

– potter's wheel