The alumina ceramics is a ceramic, a wide range of uses, superior performance, to meet in the daily and special performance needs.
1 Molding method
(1) Dry press forming
Alumina ceramics dry press forming technology is limited to the shape and the inner wall thickness more than 1mm alone, the length and diameter ratio is not more than 4:1 objects. Method of forming a uniaxial or biaxial. Compressor having hydraulic, mechanical type two, a semi-automatic or fully automatic molding method. As the hydraulic press stroke uniform pressure, so the powder filling there are differences when pressing different height. Mechanical type compressor pressure size because of the powder filling much change, easily lead to sintering shrinkage difference, affect the quality of the product. So dry pressing process of powder particles are uniformly distributed on the mold filling is very important. Filling quantity determines the precision of manufacture of alumina ceramic parts size precision control of great influence.
(2) Injection molding method
Injection molding is the earliest use of alumina ceramic forming method. Due to the adoption of the gypsum mold, low cost and easy forming of large size, the shape of complex parts. Injection molding is the key of alumina slurry preparation. Usually in water flux as medium, adding solution of glue and adhesive after grinding, fully exhaust, then pour into the gypsum mould. As a result of plaster mold capillary water absorption, slurry and solidification in mould. Hollow grouting, in the mold wall adsorption slurry up to required thickness, the excess slurry pouring. In order to reduce body shrinkage, should try to use high concentration slurry.
Alumina ceramic slurry is needed in the organic additives added to make slurry particle surface electric double layer formation to make the slurry stable suspension of precipitation. In addition to adding vinyl alcohol, methyl cellulose, alginate amines such as binder and polypropylene amine, Arabia gum aliquots powder, purpose is to make slurry for grouting forming operation.
2 Strengthening technology
In order to reinforced alumina ceramics, significantly improve the mechanical strength, foreign introduced a alumina ceramic strengthening technology. The process has the advantages of novel and simple, the techniques in alumina ceramic surface by electron beam, vacuum coating, vacuum coating sputtering or chemical vapor deposition method, plating a layer of silicon compound film, in 1200℃-1580 ℃heating treatment, the alumina ceramics toughened. The reinforced alumina ceramic mechanical strength can be in the original basis of substantial growth, obtained with ultra high strength of alumina ceramic.
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