Binders slip casting

The synthesis of 5 lan thick Ti02 Si02 layers on a porous support can be performed using the procedure given below. First a mixed Ti[(OMe)3]4 alkoxide is synthesized by reacting partially hydrolyzed Si(OMe)4 with Ti-isopropoxide. This inorganic polymer is hydrolyzed at pH 11.0 and treated with 2-methyl-2-4-pentanediol and a binder. This solution is then slip-cast onto a porous support, dried and calcined at 700°C. The membrane can be useful in reverse osmosis applications. 

As mentioned in the previous paragraph, binder and plasticizer concentrations for tape casting are much higher than for slip casting and for most other types of slurry... 

Casting of a concentrated Slip casting Free-flowing slurry with low binder content Thin intricate shapes... 

Every ceramic formation process uses binders to hold the system together, to hold the ceramic particles in relative position to each other. Clays use the organic material inherent in the natural clay product. Some casting formulations take advantage of electrostatic forces, van der Waals attractive forces, etc. Some use very stiff binders to retain shape, like polyacrylic disper-sant/binders in slip casting. Some use binders that are mushy when wet but harden during drying. 

Film-forming polymers that are soluble in water have been used in the ceramic industry for many, many years. Those knowledgeable in dry pressing are probably familiar with polyvinyl alcohol. Those versed in extrusion are likely familiar with one or more cellulose ethers. These polymeric binders are widely used to impart strength and stiffness to pressed, extruded, and slip-cast parts. These binders have also been explored for use in tape casting. Slip formulations using water-soluble polymers such as PVA and celluloses, di,i2,i3,i4 well as polyacrylic acid can be easily discovered in published literature. 

A recent review of slip casting is given by Fries and Rand (35) and much practical details of the process can be found in a set of earlier articles (36). In the process, a slurry is poured into a microporous plasto- of Paris mold. The porous nature of the mold provides a capillary suction pressure, estimated to be of the ordo- of —0.1-0.2 MPa, which draws the liquid from the slurry into the mold. A consolidated layer of solids, referred to as a cast (or cake), forms on the walls of the mold (Fig. 6.33). After a sufficient thickness of the cast is formed, the surplus slip is poured out and the mold and cast are allowed to dry. Normally, the cast shrinks away from the mold during drying and can be easily removed. Once fully dried, the cast is heated to burn out the binder and sintered to produce the final article. Examples of slip casting compositions are given in Table 6.9. 

Ceramics Slip casts Binder (promotes green strength)... 

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