IT 111 Ceramics, Adhesives, Elastomers

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IT 111 Ceramics, Adhesives, Elastomers

• Lecture 10
• Thomas E. Scott

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Ceramics

• Complex compounds containing
• Metals
• Non-Metals
• Heated to near incandescence
• Very high melting points gt 3500F
• Typically hard and brittle
• High resistance to heat
• Applications tile, brick, glass, China,
  pottery, magnets, cutting tools, super
  conductors, refractories (materials than can
  endure high heat)

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Ceramics
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Ceramics

• Traditional ceramics
• Made from clay, silica and feldspar
• Technical ceramics
• Made from pure compounds
• Oxides, nitrides, carbides
• Alumina, silicon carbide, silicon nitride, barium
  titanate (capacitors and piezoelectric crystals)
• Hot pressed into useful products

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Ceramics

• Blend materials to form a plastic mass
• Extrude, press, or cast (slurry)
• Dry to remove liquid
• Fire to fuse materials (Sinter)
• Apply glaze
• Finished product susceptible to cracking under
  rapid heating or cooling (spalling)
• Pyrex contains boric oxide to prevent spalling

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Ceramics

• Glass supercooled liquid
• Rigid and hard seems like a solid
• No continuous lattice therefore acts like a
  liquid
• Transparent or translucent
• Produces refraction
• Constituents produce different properties
• Plate, window, Pyrex, etc

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Ceramics

• Stone major constituents
• Slicon dioxide (Quartz, Granite)
• Alumina silicate (Sandstone)
• Calcium carbonate (Limestone, Marble)
• Major stone used in construction
• Marble can be polished
• Shale Silica and alumina
• Slate Mud and clay

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Ceramics

• Clay composed of silica and alumina
• Bricks
• Types determined by material and firing range
• Carbide cutting tools
• Cobalt embedded with
• Tungsten (Tungsten carbide)
• Titanium
• Tantalum
• Cermet Ceramic particles fused with powdered
  metal

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Abrasives

• Hard material used to wear a softer material
• Diamond hardest machining
• Silicon Carbide (Carborundum) cutting wheels
• Aluminum Oxide grinding wheels

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Adhesives

• Bonding materials using another material
• Mechanical theory
• Surfaces have peaks and valleys
• Adhesive fills and mechanically locks
• Therefore roughening helps
• Molecular theory
• Van der waals forces at molecular level
• Molecules cling through adhesion force

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Adhesives

• Important parameters
• Extent of wetting
• Curing time
• Surface preparation
• Joint configuration
• Applications
• Auto, aerospace, multiple products
• Replacing welding, riveting, nailing, screwing

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Adhesives

• Glue
• Animal or vegetable (organic)
• Cement
• Elastomer based (rubber, celluloid, magnesia
  for masonry)
• Thermoplastic
• Hot melt adhesive glue gun
• Thermoset
• Epoxies, phenolic resins

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Elastomers

• Polymers with resilience
• Ability to be elongated and recover
• Natural rubber latex
• Add sulfur and vulcanize
• Long chains of molecules
• Fill with silica, carbon black (tires)
• Thermoplastic elastomers
• Hoses, Butadiene, neoprene, butyl rubber