Use of a coating composition and corresponding method for producing a centrifugal casting mould with a coating

A method for producing a centrifugal casting mold provided on its inner walls with a refractory coating, for use in the centrifugal casting process, having the following steps:

• providing or producing a refractory coating composition
• applying one or more coats of the provided or produced coating composition to the inner walls of the centrifugal casting mold, preferably with the centrifugal casting mold rotating and/or heated,
• wherein the refractory coating composition is a dispersion of refractories in an aqueous phase, the refractories at least comprising
• (a) a total amount in the range from 4 to 50 wt % of particulate amorphous oxide, based on the total mass of the coating composition,
• wherein the particulate amorphous oxide comprises a fraction of 85 wt % or more of silicon dioxide, based on the total amount of the particulate amorphous oxide,
• wherein the particulate amorphous oxide possesses a mass-based D95 of less than 5 μm, determined by laser diffraction,
• wherein the particulate amorphous oxide possesses a porosity of less than 50%, based on the total amount of the particulate amorphous oxide, and
• wherein 90 wt % or more of the particles of the particulate amorphous oxide possess a sphericity of greater than 0.9, determined by evaluating two-dimensional microscope images, or
• a total amount in the range from 4 to 50 wt % of microsilica as particulate amorphous oxide, based on the total mass of the coating composition, and one or more further refractories,
• (b) wherein 98 wt % or more of the total mass of the refractories are capable of passing through a sieve having a mesh size of 0.75 mm.

A method for producing a casting in the centrifugal casting process, comprising the steps of:

• providing or producing a refractory coating composition,
• applying one or more coats of the provided or produced coating composition to the inner walls of a centrifugal casting mold, to produce a refractory coating,
• introducing the casting metal into the rotating centrifugal casting mold whose inner walls have been coated,
• solidifying the casting in the rotating centrifugal casting mold,
• extracting the casting from the centrifugal casting mold,
• wherein the refractory coating composition is a dispersion of refractories in an aqueous phase, the refractories at least comprising
• (a) a total amount in the range from 4 to 50 wt % of particulate amorphous oxide, based on the total mass of the coating composition,
• wherein the particulate amorphous oxide comprises a fraction of 85 wt % or more of silicon dioxide, based on the total amount of the particulate amorphous oxide,
• wherein the particulate amorphous oxide possesses a mass-based D95 of less than 5 μm, determined by laser diffraction,
• wherein the particulate amorphous oxide possesses a porosity of less than 50%, based on the total amount of the particulate amorphous oxide, and
• wherein 90 wt % or more of the particles of the particulate amorphous oxide possess a sphericity of greater than 0.9, determined by evaluating two-dimensional microscope images, or
• a total amount in the range from 4 to 50 wt % of microsilica as particulate amorphous oxide, based on the total mass of the coating composition, and
• (b) one or more further refractories,
• wherein 98 wt % or more of the total mass of the refractories are capable of passing through a sieve having a mesh size of 0.75 mm.