Stable protective coating layer for ceramic surface of casting mold, especially for aluminum, includes oxide ceramic structural component and polymerized phosphate component

摘要

Ceramic surface for a casting mold comprises a layer (I) of (a) polymerized product infiltrated and/or diffused into a base material, (b) a structural part of alumina, silica, titania and/or zirconia in a 80-200 nm fraction and (c) a polymer comprising polymerized monoaluminum, monozinc, monomagnesium, sodium and/or boron phosphate, enclosing at least some of the primary, structural and sliding parts. Independent claims are included for: (a) a separating composition (A) for the production of a ceramic surface layer (I) as above, formed from completely demineralized water and containing (i) an acid former in the form of sodium hydroxide, potassium hydroxide and/or aluminum chloride, (ii) a phosphate-containing binder in the form of monoaluminum, monozinc, magnesium, manganese and/or boron phosphate, (iii) a structural part in the form of alumina and/or silica as 80-200 nm fraction and (iv) an organic dispersant; and (b) a method for forming a layer on a ceramic surface, involving applying (A) to the surface and heating the surface to 200[deg]C or more to cause chemical bonding of the phosphate with the ceramic and polymerization of the binder.