Drying performance of kaolin

The drying performance of kaolin clay refers to the performance of kaolin clay throughout the drying process. Including dry shrinkage, dry compressive strength, and dry sensitivity.

Dry shrinkage refers to the shrinkage of kaolin clay material caused by water shortage and dry shrinkage. Kaolin clay generally undergoes dehydration and dryness at temperatures ranging from 40-60 ℃ to no more than 110 ℃. Due to the discharge of water, the spacing between particles decreases, and the length and volume of the specimen require shrinkage. Dry shrinkage is divided into linear shrinkage and volumetric shrinkage, expressed as the percentage of change in length and volume of kaolin clay from dry shrinkage to compaction test. The dry shrinkage of kaolin is generally 3-10%. The denser the particle size distribution, the larger the specific surface, the better the ductility, and the greater the dry shrinkage. The shrinkage of the same type of kaolin varies depending on the amount of water it is mixed with. If there is more, the shrinkage will be greater. In ceramic art, excessive dry shrinkage can easily cause deformation or cracking of the body. The dry compressive strength refers to the flexural strength of the mud after the dry compaction test.

Dry sensitivity refers to the difficulty coefficient level at which deformation and cracking tendencies are likely to occur when the green body is dry. High sensitivity, easy to deform and crack during the entire drying process. Generally, kaolin with high dry sensitivity (dry sensitivity index K>2) is prone to defects; The lower one (with a sensitivity index K<1) is safer in irritability.