NONMETALLIC STRUCTURAL MATERIALS Polymers (plastics) Ceramics Glass (amorphous materials)

Composition of Ceramics Crystal phase – basic part of ceramics structure Amorphous (glassy) phase – binder Gas phase in ceramics pores CERAMICS Oxide ceramics Oxigen-free ceramics based on based on Al2O3 ZrO2 SiC Si3N4 and other oxides Metal ceramics, or cermets

Advantages of Ceramics High hardness and wear resistance High service temperature ( up to 3500 °С) Corrosion resistance in various environments Low electric conductivity (dielectrics) Heat insulators Low labour input of processing (both product and material are created simultaneously; strengthening and finishing operations are not required) Low density

Basic Lacks of Ceramics Britlness (impact strength of ceramics is 40 times less than metals have) Oxide ceramics does not withstand the sharp changes of temperature Oxigen-free ceramics can be obtained by hot pressing only (technological problems)

Ceramics always is multiphase substance Structure of Ceramics Scheme Microstructure (photo) Crystal phase includes yellow, brown, white, and blue grains; amorphous phase is violet; pores are black Ceramics always is multiphase substance

Ceramic Shrinkage in Sintering A ready porcelain figure and a cup have the sizes approximately 13 % less than green (unburnt) work-peaces 6

Application of Ceramics Building ceramics: bricks and tile These buildings in Amsterdam are more than 400 years old

Application of Ceramics Pyramids are the most ancient building structures Khafr’s Pyramid and Great Sphinx Great pyramids in Giza: XXVI century B.C.

Application of Ceramics: technical alumina ceramics Thread feeders, spools (parts for weaving industry) Nozzles of torches Dies for wire drawing Sanitaryware items Parts of machines

“Ductile” ceramics based on ZrO2: the stress near the growing crack tip causes a phase transformation; a new phase with bigger specific volume hinders crack growth

Fracture toughness К1С describes the local increasing in tensile stress near the crack tip in the moment of transition from stable growth stage to unstable one. Fracture toughness of ceramic materials is determined by the length of the longest crack forming in the coarse of Vickers hardness testing.

Building Ceramics Bricks and ceramic tiles are formed and baked clay; their composition: hydrated aluminosilicates Al2(Si2O5)(OH)4 and impurities. Cement is a mix of limestone CaO, silicon dioxide SiO2 and aluminium oxide Al2O3. It hardens being mixed with water. Concret is a composite material including sand and stones, binded together with hardened cement. Ratio sand to gravel is 60:40. 12

Building Ceramics Strength property of concrete is quality class by axial compression strength: (a) Stretching (b) Compression Concrete fracture by compression 13

Glass Structure Scheme of spatial glass structure in quartz glass Arrangement of tetrahedrons in quartz glass Quartz glass Alcali glass

Application of Glass Constructional glass: window glass pane Art glass works

Technical glass: insulators of power line Application of Glass Technical glass: insulators of power line

Glass Ceramics Pyroceramics processing from blast-furnace slag Scheme of glass crystallization Pyroceramics processing from blast-furnace slag

Glass Ceramics × 7500 (grain size 1-2 μm) Process of glass crystallization × 7500 (grain size 1-2 μm) a b c d