Insulated investment casting mold and method of making

A method of making an insulated investment casting shell mold comprising:

• Mixing at least one refractory material with a slurry vehicle forming a prime coat slurry;
• mixing at least one refractory material with a slurry vehicle forming a backup coat slurry;
• said prime coat slurry having the same or different composition as said backup coat slurry,
• applying a coating of said prime coat slurry onto a fugitive pattern to produce a prime coated pattern;
• applying stucco onto said prime coated pattern;
• drying the stuccoed, prime coated pattern;
• applying a plurality of separate coatings of said backup coat slurry onto the stuccoed, prime coated pattern to produce a backup coated pattern;
• after each of said separate applications of said backup coat, applying stucco onto the backup coated pattern and drying each of said stucco applications;
• providing a third slurry having the same or different composition as said prime or said backup slurry and adding at least one foaming agent and at least one stabilizer to said third slurry;
• introducing small, stable gas bubbles, compared to gas bubbles formed by the foaming agent alone, into said third slurry containing said foaming agent and said stabilizer;
• entraining a plurality of said small, stable gas bubbles in said third slurry containing said stabilizer and said foaming agent forming an insulating slurry having closed porosity therein;
• applying said insulating slurry onto at least a portion of said backup coated pattern forming a green shell mold;
• removing said pattern from said green shell mold;
• and
• firing said green shell mold forming said insulated investment casting shell mold with a reduced thermal diffusivity as a result of said closed porosity thereby slowing the cooling of material cast within said insulated investment casting shell mold.

A method of making a bubbled insulating slurry for use in an insulated investment casting shell mold with a reduced thermal diffusivity thereby slowing the cooling of material cast within said insulated investment casting shell mold comprising the steps of:

• providing a slurry vehicle;
• mixing at least one refractory material with said slurry vehicle to form a slurry;
• adding at least one stabilizer to said slurry;
• adding at least one foaming agent to said slurry;
• introducing small, stable gas bubbles, compared to gas bubbles formed by the foaming agent alone, into said slurry containing said foaming agent and said stabilizer;
• entraining said small, stable gas bubbles in said slurry containing said stabilizer and said foaming agent thereby causing said slurry to maintain said gas bubbles to form a bubbled insulating slurry having closed porosity therein.