High temperature investment material and method for making solid investment molds
AssigneePrecision Metalsmiths, Inc.
InventorsRobert A. Horton, Claude H. Watts
Life of this patent
Estimating the term…
Abstract
An improved phosphate-type refractory investment material and method for marking solid investment molds especially useful for casting high melting point metals and alloys, such as platinum and the like. The material consists essentially of one or more phosphate salts, one or more water soluble organic acids, and refractory powder. The material can be prepared as a dry powder blend which is easily shipped to the user and mixed with water at the time of investing the flask. Alternatively, the salt and/or organic acid can be combined with the refractory powder at the time of mixing with water.
Claims17
A dry investment powder blend suitable for making investment molds consisting essentially of:
- phosphate salt,
- water soluble organic acid, and
- at least one refractory powder selected from the group consisting of silica, alumina, zircon, zirconia and high alumina aluminum silicates.
A dry investment powder blend as claimed 3 wherein:
- a) said monobasic phosphate salts have the general formulae AH2PO4 and BH4(PO4)2 where A is ammonium or at least one monovalent metal of Group IA of the Periodic Table and B is a divalent metal,
- b) said dibasic phosphate salts have the general formulae A2HPO4 and BHPO4 wherein A and B are as defined above, and
- c) said tribasic phosphate salts have the general fomulae A3PO4, ABPO4, B3(PO4)2 and CPO4 where A and B are as defined above and C is at least one trivalent element of Group III of the Periodic Table.
A dry investment powder blend for making investment molds consisting essentially of:
- a) from about 0.02-4.00% phosphate salt which is at least one member of the group consisting of monobasic, dibasic, tribasic and condensed polyphosphate salts,
- b) from about 0.01-3.00% of at least one water soluble organic acid having a melting point above room temperature, and
- c) the balance refractory powder, said refractory powder being at least one member selected from the group consisting of silica, alumina, zircon, zirconia, and high alumina aluminum silicates.
A method of making an investment mold comprising the steps of:
- a) providing a slurry consisting essentially of a refractory powder, phosphate salt, water soluble organic acid and water, wherein the refractory powder is at least one member selected from the group consisting of silica, alumina, zircon, zirconia and high alumina aluminum silicates,
- b) investing a disposable pattern with the slurry,
- c) allowing the slurry to set to form a mold, and
- d) removing the disposable pattern from the mold.
Dependencies are inferred from the claim text.