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CERAMIC FABRICATION TECHNIQUES, CERAMIC, :pencil2:No drying shrinkage…

- - - - PRESSING
        
        (1) Glass hob s fed into mold from furnace
        (2) Pressing into shape by plunger
        (3) Plunger is retracted and finished produced is removed
        
        :red_flag:For mass production of flat products such as plates, dishes, bake ware and TV tube faceplates
      - PRESS-AND-BLOWING
        
        (1) Molten gob is fed into mold cavity
        (2) Pressing to form a parison
        (3) The partially formed parison, held in a neck ring, is transferred to the blow mold
        (4) Blown into final shape
        
        :red_flag:Production of wide-mouth containers such as jars
      - BLOW-AND-BLOWING
        
        :red_flag:Production of smaller-mouth containers such as beverage bottles and incandescent light bulbs
        
        (1) Gob is fed into inverted mold cavity
        (2) Mold is converted
        (3) First blowing step
        (4) Partially formed piece is reoriented and transferred to second blow mold
        (5) Blown into final shape
      - CASTING
        
        :red_flag:Relatively massive objects such as telescope lenses and mirrors
        
        (1) Molten glass poured into the mold (sufficiently fluid)
        (2) After cooling and solidifying, piece must be finished by lapping and polishing
    - - (i) SHAPING OF FLAT GLASS
        
        ROLLING OF FLAT PLATE
        
        :red_flag:Starting glass from melting furnace is squeezed through opposing rolls whose gap determines sheet thickness followed by grinding and polishing for parallelism and smoothness
        
        FLOAT PROCESS
        
        :red_flag:Molten glass flows onto the surface of a molten tin bath where it spreads evenly across the surface, achieving a uniform thickness and smoothness
      - (ii) Shaping of tubular glass
        
        DANNER PROCESS
        
        :red_flag:Molten glass flows around a rotating hollow mandrel
        through which air is blown while the glass is drawn.
    - - FIBROUS GLASS
        :checkered_flag:For thermal insulation, acoustical insulation and air filtration
        :checkered_flag:CENTRIFUGAL SPRAYING
        
        PRINCIPLE
        The molten glass flows into a rotating bowl with many smal l orifices (opening) around its peripheryl (outer edge)
      - LONG CONTINUOUS FILAMENTS
        :checkered_flag:Suitable for fiber reinforced
        plastics, yarns, fabrics, and fiber optics
        :checkered_flag:GLASS FIBER DRAWING
        
        PRINCIPLE
        produced by drawing (pulling) strands of molten glass (by gravity) through small orifices in a heated plate made of a platinum alloy
- - - - (a) HAND MODELLING
        Only a mold is used to define portions of the part geometry
        HAND THROWING
        Products of circular cross-section can be formed by throwing and shaping the clay
      - (b) JIGGERING OR JOLLEYING
        (1) Wet clay slug is placed on a convex mold
        (2) Batting is pressed into the slug to proved the initial rough shape of bat
        (3) A heated jigger tool imparts the final product shape by pressing the profile into the surface
      - (c) PLASTIC PRESSING
        A forming process in which a plastic clay slug is pressed between upper and lower molds contained in metal rings (Molds are made of a porous material)
      - (d) EXTRUSION
        Compression of a stiff plastic ceramic mass through a die orifice to produce long sections of uniform cross section, which are then cut to required piece length
        Products: hollow bricks, shaped tiles, brick, drain pipes, tubes, and insulators
- - - - :red_flag:Ceramic particles are mixed with a thermoplastic polymer, then heated and injected into a mold cavity
        :red_flag:The polymer acts as a carrier and provides flow characteristics for molding
        :red_flag:Upon cooling which hardens the polymer, the mold is opened and the part isremoved
    - - (i) UNIAXIAL COMPRESSION
        (a)The die cavity is filled with powder
        (b) The powder is compacted by means of pressure applied to the top die
        (c) The compacted piece is ejected by rising action of the bottom punch
        (d) The fill shoe pushes away the compacted piece and the fill is repeated
      - (ii) ISOSTATIC COMPRESSION
        :red_flag:Uses hydrostatic pressure to compact the ceramic powders from all directions
        :red_flag:Avoids the problem of nonuniform density in final product
      - (iii) HOT PRESSING
        :fountain_pen: It is carried out at elevated temperatures so sintering of the product is accomplished simultaneously with pressing.
        :fountain_pen:It is mainly for densification of ceramics, eliminates the need for a separate firing step
    - - (1) Preparation of a powdered ceramic material and a liquid into a stable suspension called a slip
        (2) Pour the slip into a porous mold made of plaster of and allowing the liquid portion of the slip to be partially absorbed by the mold
        (3) When the sufficient wall thickness has been formed, the excess slip is poured out of the cavity
        (4) The material in the mold is allowed to dry to provide adequate strength for handling
    - - :red_flag:Thin sheets of green ceramic are casted as a flexible tape
        :red_flag:These sheets are casted from liquid slip (ceramic + organic solvent + binders + plasticizers)
        :red_flag:Used for integrated circuits and capacitors
- - - - :fountain_pen:It is the simplest glass
        :fountain_pen:Main component: silica
        PROPERTIES
        a) High purity and optical transparency
        b) High softening point
        c) Low coefficient of thermal expansion
        d) Chemical durability
        e) Difficult and expensive to produce
        USES
        Laboratory glassware, lenses, telescope mirrors, optical fibers
    - - :fountain_pen::It is the most common glass
        :fountain_pen:Produced by heating silica with NaO2 and CaO
        PROPERTIES
        a) Low softening point
        b) High thermal coefficient of expansion
        c) Low resistance to chemical attacks
        USES
        Window panes, light bulbs, bottles, glass containers
    - - :fountain_pen:Known as lead crystal
        :fountain_pen:Made by using PbO and KO2
        :fountain_pen:High refractive index & soft surface
        PROPERTIES
        a) High refractive index
        b) High density
        c) Attractive glittery
        USES
        a) Prisms
        b) Decorative objects
    - - :fountain_pen:Formed when boron oxide is added to soda-lime glass
        PROPERTIES
        a) Very low thermal expansion coefficient
        b) High softening point
        c) Resistant to thermal shock
        d) Chemically shock
        USES
        Laboratory glassware, cookware, glass container