Ceramics and Raw Materials Quiz

Fundamentals of Ceramic Materials

• This is a course on ceramic materials, offered in the Fall of 2024-2025, by Prof. Dr. Filiz Şahin.
• The course is offered by the Department of Metallurgical & Materials Engineering at Istanbul Technical University (I.T.U).

Powder Processing

• This is a topic within the wider curriculum of Fundamentals of Ceramic Materials.

Ceramic Raw Materials

• The raw material's properties significantly influence finished ceramic components.
• Factors like purity, particle size, reactivity, polymorphism, availability, and cost are crucial.
• Traditional raw materials are naturally occurring, such as clay minerals and quartz sand, used in traditional ceramics like tiles and bricks.
• Advanced ceramics are synthetic powders obtained through specialized synthesis processes, used in high-precision applications like space shuttle tiles, engine components, artificial bones/teeth, and electronics, achieving optimal final product properties through high purity and advanced production methods.

Traditional Ceramics Raw Materials

• Ceramics have been produced for centuries, employing raw materials molded into shapes and hardened by high-temperature fires.
• Table 9.1 lists traditional ceramic subgroups and their products (e.g., whitewares, heavy clay products, refractories, construction products, abrasives, glass).

Ceramic Tile Production Process

• A flow chart (Figure 1) details the process, beginning with raw material storage, then batching, grinding, atomization (spray drying), storage silos, sieving, and pressing.
• Subsequent steps include drying, green storage, firing, fired product storage, sorting, and packing for warehousing.

Additional Diagrams and Figures

• Figures 2 and 3 provide graphical descriptions of relevant processes like ball mills and spray dryers respectively (including their component parts).
• Figure 4 depicts a hydraulic press, while Figure 5 showcases a fast firing roller hearth kiln, both essential for ceramic tile production.

Clay Minerals

• Key components of many ceramic products.
• Hydrated aluminosilicates, with chemically bound water.
• Form the basis of pottery and building materials.
• Derived from the weathering and sedimentation of aluminosilicate rocks.
• Physical characteristics, including color, and chemical compositions.
• Purity, particle size distribution etc matter for proper use.
• Common impurities include oxides of Ba, Ca, Na, K and Fe, along with organic matter. The average particle size is 2 to 4 µm.
• Unique morphology (plate-like) creates easy cleavage with narrow particle size distribution, making them easily movable over each other.
• Essential for the development of plasticity in ceramic bodies when mixed with water.
• Structural clay products and whitewares are the two common classifications of clay-based products.
• Key properties are plasticity, cohesion, and color.

Clay Properties

• Plasticity: develops when mixed with water enabling molding and shaping.

• Cohesion: maintains shape after drying

• Color: Varies depending on the mineral mix (e.g., white if pure, dark/red/violet for impurities

• Important components of some products are explained.

• Different types of clay minerals are detailed (e.g., Ball Clay, Bentonite, Common clay, Fire clay, Fuller's earth, Kaolin.)

### Kaolinite

• A primary clay mineral.
• Key component in most ceramics.
• Details on kaolin formation, including primary and secondary formation mechanisms.
• Chemical composition (A12O3, SiO2, H2O).
• Chemical reactions during heating.

Quartz

• Common mineral found on Earth, an important component in many types of ceramics, including glass, glazes, enamels, refractories, abrasives, and whitewares.
• Silica (SiO2) is its significant form and part of sand, sandstone, and quartzite.
• Doesn't exhibit plasticity but enhances ceramic body strength at high temperatures.
• Types of quartz and qualities are detailed.

Feldspar

• Essential in ceramic production, important after clay, composing 60% of Earth's crust.

• Comprised of KAlSi3O8 (Orthoclase), NaAlSi3O8 (Albite), and CaAl2Si2O8 (Anorthite)

• Acts as a fluxing agent, facilitating the formation of glassy phases at low temperatures.

• Crucial for enhancing ceramic body strength, toughness, glass scratch resistance, and thermal shock tolerance.

• Detail of melting range (temp), composition, and other properties are provided.

Wollastonite

• Forms from the interaction of limestones and silica in high-temperature magmas.
• Composition (48.3% CaO, 51.7% SiO2)
• Useful as a refractory material and filler for paints.
• Improves ceramic properties like brightness, whiteness, low moisture/oil absorption, and low volatile content.
• Used in ceramics, friction materials, metal processing, paints, and plastics.

Talc

• Hydrated magnesium silicate, naturally occurring material used extensively in some ceramic production processes.

• Talc's properties regarding chemical composition (MgO, SiO2, OH, and H2O), temperature decomposition, formation, and its use in ceramics are provided.

• Used in ceramics, including tiles and dinnerware.

Advanced Ceramics

• Refers to ceramics engineered with controlled composition/structure.
• Materials produced through refining naturally occurring minerals or through new synthesis strategies.
• These materials are commonly used in demanding applications where higher performance is needed (e.g., electronics, aerospace, medical applications).

Alumina

• Most important advanced oxide ceramic.
• Key characteristics like high strength, exceptional dielectric properties, high temperature resistance, corrosion resistance.
• Processing of alumina. Methods used to produce alumina from bauxite ore, including the Bayer process, and its main steps- digestion, clarification, precipitation, calcination are detailed.
• Types of alumina products, like low soda alumina and reactive alumina are outlined along with their properties and typical applications.
• Fused alumina and tabular alumina are specific types of alumina characterized by their production methods, and unique properties.

Silicon Carbide (SiC)

• Used in a wide array of applications, including abrasives, refractories, and metallurgical applications.
• Characterized by its high thermal conductivity, low thermal expansion, and excellent thermal shock resistance.
• There are two phases (alpha and beta) with distinct properties and applications in different domains, depending on the application
• Production techniques (e.g., Acheson, HSC) along with the chemical reactions, are described.

Silicon Nitride (Si₃N₄)

• Properties and applications in many domains
• Methods of powder production
• Crystal structures