Post on 07-Apr-2018
Asst. Prof. Dr. Ayşe KALEMTAŞ
MME391 CeramicMaterials
Asst. Prof. Dr. Ayşe KALEMTAŞ
Bursa Technical University, Metallurgical and Materials Engineering Department
Office Hours: Tuesday, 10:00-11:00ayse.kalemtas@btu.edu.tr, akalemtas@gmail.com
Asst. Prof. Dr. Ayşe KALEMTAŞ
CLASSIFICATION OF CERAMICS
Ceramic Materials
Advanced Ceramics Traditional Ceramics
Made from artificial or
chemically modified raw
materials.
Mainly made from natural raw materials such as
kaolinite (clay mineral), quartz and feldspar.
Asst. Prof. Dr. Ayşe KALEMTAŞ
Advanced Ceramics
Chemically prepared powders
Precipitation, spray drying, freeze
drying, vapor phase, sol-gel
Slip casting, injection molding, sol-gel,
hot-pressing, HIPing, rapid prototyping,
Electric furnace, hot press, reaction
sintering, vapor deposition, plasma
spraying, microwave furnace
Erosion, laser machining, plasma
spraying, ion implantation, coating
Light microscopy, X-ray diffraction, electron
microscopy, scanned probe microscopy, neutron
diffraction, surface analytical methods
Raw Materials
Preparation
Forming
High temperature
processing
Finishing
Characterization
Traditional
Ceramics
Raw minerals
- Clay
- Silica
Potters wheel, slip
casting, pressing
Flame kiln
Erosion, glazing
Visible examination,
light microscopy
Advanced versus Traditional Ceramics
Asst. Prof. Dr. Ayşe KALEMTAŞ
Raw Material Selection Criterias
Raw material cost
Market factors
Technical process parameters
Performance of the desired product
Market price of the product
Asst. Prof. Dr. Ayşe KALEMTAŞ
CERAMIC RAW MATERIALS
Ceramic Materials
Naturally occurring minerals Synthetic materials
their origin locations in which they can be found their relative abundance
Naturally occurring minerals requireextraction, which is often a regional industrylocated close to abundant quantities of thenatural deposit.
Most minerals need to go through some formof physical or chemical processing before use.The collective term for these processes isbeneficiation.
When you understand how oxides aremanufactured, it will be clear why they areoften impure and why Si, Na, Ca are themajor impurities.
borides (TiB2, BN, etc.) carbides (SiC, B4C, TiC, etc.) nitrides (AlN, Si3N4, TiN, etc.) oxides (TiO2, Al2O3, etc.)
These ceramics are becoming morecommon, but are generally expensiveand desire special processingenvironments.
For many nonoxides the mainimpurities are often components ofthe starting material which was notreacted, e.g., Al in AlN or Si in Si3N4.
Asst. Prof. Dr. Ayşe KALEMTAŞ
CERAMIC RAW MATERIALSCategory Purity, % Materials
Crudematerials
VariableShales, stoneware clay, tile clay, crude
bauxite, crude kyanite, natural ball clay, bentonite
Industrialminerals
85-98
Ball clay, kaolin, refined bentonite, pyrophyllite, talc, feldspar, nepheline syenite, wollastonite, spodumene, glass sand, potter’sflint (quartz), kyanite, bauxite, zircon, rutile,
chrome ore, calcined kaolin, dolomite
Industrialinorganicchemicals
98-99.9
Calcined alumina (Bayer process), calcinedmagnesia (from brines, seawater), fused
alumina, fused magnesia, aluminum nitride,silicon carbide, silicon nitride, barium
carbonate, titania, calcined titanates, ironoxide, calcined ferrites, zirconia, stabilized
zirconia, calcined zirconates
Specialinorganicchemicals
99.9 Various materials (Si3N4, TiB2, SiC, BN, etc)
Asst. Prof. Dr. Ayşe KALEMTAŞ
Synthetic Materials
OXIDES
The raw materials used for oxideceramics are almost entirelyproduced by chemical processes toachieve a high chemical purity and toobtain the most suitable powders forcomponent fabrication.
NON-OXIDES
Most of the important non-oxideceramics do not occur naturallyand therefore must be synthesized.The synthesis route is usually one ofthe following:
Combine the metal directly withthe nonmetal at high temperatures.
Reduce the oxide with carbon athigh temperature (carbothermalreduction) and subsequently react itwith the nonmetal.
Asst. Prof. Dr. Ayşe KALEMTAŞ
Minerals
• Minerals are defined as (1) naturallyoccurring, (2) inorganic substanceswith a narrow range of (3) chemicalcomposition and (4) characteristicphysical properties.
• An example: The naturally occurringform of the compound sodium chlorideis the mineral halite.
Asst. Prof. Dr. Ayşe KALEMTAŞ
MineralsMohs Hardness Scale
Mohs' scale of mineral hardness quantifies the scratch resistance of minerals by comparing the ability of a harder material to scratch a softer material.
The Mohs scale was invented in 1812, by the German mineralogist Friedrich Mohs. Mohs based his scale on ten minerals.
Mineral Hardness
Talc 1
Gypsum 2
Calcite 3
Fluorite 4
Apatite 5
Feldspar 6
Quartz 7
Topaz 8
Corundum 9
Diamond 10
http://www.allaboutgemstones.com/mohs_hardness_scale.html
Asst. Prof. Dr. Ayşe KALEMTAŞ
Minerals
http://www.allaboutgemstones.com/mohs_hardness_scale.html
1. TalcTalc is the world's softest mineral and the lowest mineral on the Mohs scale.Talc is a hydrated magnesium sheet silicate which is highly insoluble in water.Talc is translucent to opaque with a iridescent or pearly luster. Talc is used incosmetics such as talcum powder, as a lubricant, and in paper manufacturing.
Absolute Hardness: 1Chemical Composition: Mg3Si4O10(OH)2
2. GypsumGypsum is a soft mineral composed of calcium sulfate dihydrate. Gypsumoccurs in nature as flattened or twinned crystals and transparent cleavablemasses called selenite. When Gypsum has a silky and fibrous texture it is calledSatin Spar.
Absolute Hardness: 2Chemical Composition: CaSO4á2H2O
3. CalciteCalcite is an anhydrous carbonate, and one of the most widely distributedminerals on the Earth's surface. It is a common constituent of sedimentaryrocks. In crystallized form, Calcite has a vitreous luster.
Absolute Hardness: 9Chemical Composition: CaCO3
Mohs Hardness Scale
Asst. Prof. Dr. Ayşe KALEMTAŞ
Minerals
http://www.allaboutgemstones.com/mohs_hardness_scale.html
4. FluoriteFluorite (fluor-spar) is a mineral composed of calcium fluoride. It is anisometric mineral with a cubic crystal habit. Fluorite is named for itsproperty of fluorescence, or its ability to fluoresce under ultraviolet light.
Absolute Hardness: 21Chemical Composition: CaF2
5. ApatiteApatite (hydroxylapatite, fluorapatite, chlorapatite) is a group of phosphateminerals and is one of few minerals that are produced by biologicalorganisms. Hydroxylapatite is the major component of tooth enamel.
Absolute Hardness: 48Chemical Composition: Ca5(PO4)3(OH-,Cl-,F-)
6. OrthoclaseOrthoclase (aka feldspar) in an igneous rock forming tectosilicate (silicate)mineral and is a key component in granite. Orthoclase derives its nameform the Greek word for "straight fracture" because of its two cleavages atright angles to each other. Orthoclase crystallizes in the monoclinic crystalsystem.
Absolute Hardness: 72Chemical Composition: KAlSi3O8
Mohs Hardness Scale
Asst. Prof. Dr. Ayşe KALEMTAŞ
Minerals
Mohs Hardness Scale7. QuartzQuartz is one of the most common minerals found inthe Earth's crust. It has a hexagonal crystal structuremade of trigonal crystallized silica (silicon dioxide). Thetypical shape of a Quartz crystal is a six-sided prismthat ends in six-sided pyramids.
Absolute Hardness: 100Chemical Composition: SiO2
8. TopazTopaz is a silicate or "nesosilicate" mineral created froma combination of aluminium and fluorine. It crystallizesin the orthorhombic system and it's crystals areprismatic in form.
Absolute Hardness: 200Chemical Composition: Al2SiO4(OH-,F-)2
http://www.allaboutgemstones.com/mohs_hardness_scale.html
Asst. Prof. Dr. Ayşe KALEMTAŞ
Minerals
9. CorundumCorundum is the crystalline form of aluminium oxide and one ofthe basic rock-forming minerals. Corundum is naturally clear orcolored by impurities. Due to its hardness, Corundum is used asan abrasive in sandpaper. Emery is an impure and less abrasivevariety of Corundum.
Absolute Hardness: 400Chemical Composition: Al2O3
10. DiamondDiamond is the hardest natural occurring material. Diamond is anatural allotrope of carbon. The crystal bond structure ofdiamonds give the stone its hardness and differentiates it fromgraphite, which is the main allotrope of carbon.
Absolute Hardness: 1500Chemical Composition: C
Mohs Hardness Scale
http://www.allaboutgemstones.com/mohs_hardness_scale.html
Asst. Prof. Dr. Ayşe KALEMTAŞ
WEATHERING
• Mechanical Weathering– Physical disintegration of rock (with no
chemical alteration)
• Chemical Weathering– Chemical alteration of minerals within the
rock– Usually softening or dissolving the minerals– Forming clays, oxides and solutes
Asst. Prof. Dr. Ayşe KALEMTAŞ
WEATHERING
• The result of mechanicalweathering– Rock falls and slides– Crushing and abrasion
Rocks physically broken apart intosediment(but composition does NOT change)
Increases surface area(lots of crushed broken pieces)
Asst. Prof. Dr. Ayşe KALEMTAŞ
WEATHERING
• Sediments of:– Parent rock– Mineral particles– Angular fragments
Sediments from Mechanical Weathering
Asst. Prof. Dr. Ayşe KALEMTAŞ
WEATHERING
Breakdown of rocks by chemical reactions that change thecomposition of rocks
What is Chemical Weathering?
HydrolysisFeldspar + Water = Clay
Feldspar
A Clay Cliff
OCCURS WHEN Water combines with mineralsmost often in granite (mica and feldspars) to form CLAY
Asst. Prof. Dr. Ayşe KALEMTAŞ
WEATHERING
Breakdown of rocks by chemical reactions that change thecomposition of rocks
What is Chemical Weathering?
CARBONATION (causes dissolving)
Rainwater containing carbon dioxide dissolves
minerals (all rain water is slightly
acidic)
Most strongly affected are calcite minerals:
Limestone and marble
Asst. Prof. Dr. Ayşe KALEMTAŞ
WEATHERING
Breakdown of rocks by chemical reactions that change thecomposition of rocks
What is Chemical Weathering?
RUSTING-OXIDATION
OXIDATION OCCURS when oxygen combines chemically with iron to form iron oxide
Asst. Prof. Dr. Ayşe KALEMTAŞ
WEATHERING
Breakdown of rocks by chemicalreactions that change thecomposition of rocks
What is Chemical Weathering?
Dissolving-ACID RAINsulfuric acid-pollution in air dissolves
in rainwater and eats away at buildings & rocks
Asst. Prof. Dr. Ayşe KALEMTAŞ
WEATHERING
• Chemical Weathering– Dissolving Dissolved ions– Oxidation Iron in Ferromag. Minerals Iron Oxides (e.g.,
Hematite)– Formation of Clays from silicates (e.g., Feldspar)
Asst. Prof. Dr. Ayşe KALEMTAŞ
WEATHERING
• Chemical Weathering– Dissolving Dissolved ions– Oxidation Iron in Ferromag. Minerals Iron Oxides (e.g., Hematite)
– Formation of Clays from silicates (e.g., Feldspar)
Oxidation: 4FeSiO3 + O2 + H2O FeO(OH) + 4SiO2
Hydration: CaSO4 + 2H2O CaSO4·2H2O
Asst. Prof. Dr. Ayşe KALEMTAŞ
WEATHERING
CLIMATE CONTROLS WEATHERING
PHYSICAL WEATHERING:COLD AND MOIST ALTERNATE FREEZE / THAW
CHEMICAL WEATHERING:WARM AND MOIST (just like a chemical
reaction)
IN BOTH CASES – WATER IS THE PRIMARY INGREDIENT THAT PROMOTES WEATHERING
Asst. Prof. Dr. Ayşe KALEMTAŞ
Minerals
Minerals may be subdivided into two majors groups:
– Oxides O2-
– Carbonates (CO3)2-
– Sulfides S2-
– Sulfates (SO4)2-
– Halides Cl-, F-, Br-
– Native elements (single elements; e.g., Au)
• Silicates (most abundant)
• Non-silicates (~8% of Earth’s crust):
Asst. Prof. Dr. Ayşe KALEMTAŞ
Minerals
FerromagnesianSilicates (Fe, Mg)
Non-ferromagnesianSilicates (K, Na, Ca, Al)
OxidesCarbonatesSulfides/sulfatesNative elements
Asst. Prof. Dr. Ayşe KALEMTAŞ
Minerals
• Silicates– Tetrahedron
• fundamental building block
• 4 oxygen ions surrounding a much smaller silicon ion
Silicates are by far the mostabundant mineral groupaccounting for more than90% of the Earth's crust.Silicates are the major rock-forming minerals. It followsthat oxygen and silicon arethe most abundant elementsin the crust.
Asst. Prof. Dr. Ayşe KALEMTAŞ
Non-Silicates
• Usually form at low temperatures–Carbonates
• Calcite - CaCO3
• Dolomite - CaMg(CO3)2–Evaporite Minerals
• Gypsum - CaSO4-2H2O• Halite - NaCl
–Oxides• Hematite
Asst. Prof. Dr. Ayşe KALEMTAŞ
NATURAL RAW MATERIALS
Clays
Silica
Feldspar
Talc
Wollastonite
Aluminum Minerals
Lithium Minerals
Flourine Minerals
Asst. Prof. Dr. Ayşe KALEMTAŞ
NATURAL RAW MATERIALS
Non-uniform, crude materials from natural deposits clays.(Montmorillonite, illite, etc.)
Asst. Prof. Dr. Ayşe KALEMTAŞ
NATURAL RAW MATERIALS
The preparation, particularly of clay, by exposure tothe weather for a long period. This helps to oxidize anypyrite present, rendering it soluble, so that this andother soluble impurities are to some extent leached out;the water content also becomes more uniform andagglomerates of clay are broken down with aconsequent increase in plasticity.
Weathering is simply the chemical and/or physicalbreakdown of a rock material. Weathering involvesspecific processes acting on rock materials at or nearthe surface of the Earth.
Weathering products of common rock-forming minerals
Asst. Prof. Dr. Ayşe KALEMTAŞ
Element Abundances
All others: 1.5%
SILICATES
Common cations thatbond with silica anions
Asst. Prof. Dr. Ayşe KALEMTAŞ
Abundance of Minerals
* : Ceramic Materials: Science and Engineering, by C. Barry Carter and M. Grant Norton, Springer, 2007, 348.
Abundance of Minerals in the Earth’s Crust *