Abstract A rapid process for forming a refractory laminate on the surface of a support structure which comprises dipping the structure in a bath comprising a sol of negatively charged colloidal particles of an inorganic substance and/or a solution of an alkaline ionic silicate to form a layer on the surface, contacting the layer on the surface with refractory stucco grains containing a setting agent to firmly set the colloidal silica or silicate and the stucco grains. This procedure is repeated until a laminate of the desired thickness is built up on the surface. Interaction between the negatively charged colloidal particles or silicate and the stucco grain-setting agent mixture results in the polymerization of the silica or silicate and thereby the immobilization of the coatings. This technique makes it possible to successively apply and set coatings to build refractory laminates in very short times without intermediate drying and without sloughing of coats. The process is particularly suited for making expendable, refractory shell molds for precision investment casting of metals by the so-called ''''lost-wax'''' technique.
The particulate refractory material of claim 1 coated with from 1 to 30 percent by weight of a basic aluminum salt having the general formula Alx(OH)yAz wherein x 1 - 8, y 1 - 20, z 1 - 4 and A is an acid anion.
Claim 2
Dependent Claim
55 words
The particulate refractory material of claim 1 coated with from 3 to 15 percent by weight of a basic aluminum salt having the general formula Alx(OH)yAz wherein x 1 - 2, y 1 - 5, z 1 - 2 and A is an acid anion selected from the group consisting of chloride, formate and acetate.
Claim 3
Dependent Claim
23 words
The particulate refractory material of claim 1 coated with a polycationic organic polymer or monomer containing a plurality of positively charged nitrogen-containing groups.
Claim 4
Dependent Claim
24 words
The particulate refractory material of claim 1 coated with positively charged colloidal particles composed of a silica core coated with a metal oxygen compound.