| 摘要 |
<p>Coatings are formed on ceramic bodies (raw, dried or burnt) by applying onto their surfaces an aq. solns. of alkali(ne earth) metal phosphates or other metal phosphates (pref. orthophosphates or condensed phosphates) drying and firing. The soln. may contain water-soluble inorganic cpds. of boron and/or silicon, and also thickness such as (carboxy)methyl cellulose, starch, dextrin etc. Colouring water-soluble or insoluble metal cpds. can be included. Coatings can be formed on ceramic tiles, plates, stones bricks etc. pref. made from the clay-feldspar-quartz system (including natural clay, kaolin, crushed stoneware etc). The phosphate ions react with ions of Al, Ca, Mg, Fe and Mn and insoluble phosphates are formed. The resulting anchoring effect (esp. in the case of polyphosphate ions) ensures firm adhesion of the coating after the drying and firing (600-1200 degrees C) operations. The coatings are not inferior to glazes, and yet their formation is much simpler. The viscosity of the aq. solns. can be adjusted as required using conventional thickeners.</p> |
