Method of casting a reactive metal against a surface formed from an improved slurry containing yttria
US4947927A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Nov 8, 1989 |
| Grant date | Aug 14, 1990 |
| Priority date | — |
| Expiry date | Nov 8, 2009 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC04B2235/5436
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
Reactive metals, such as titanium or nickel-chrome superalloys containing rare earths, are cast with mold and/or core surface areas formed from an improved slurry. The improved slurry contains yttria to form an inert surface which is exposed to the molten reactive metal. In order to prevent premature gelation of the slurry, the forming of defects in the mold and/or core surface areas, and the forming of defects in the cast article, the slurry contains a source of hydroxyl ions. The source of hydroxyl ions is sufficient to result in the slurry having a pH of at least 10.2 six days after initially mixing the slurry. The source of hydroxyl ions may be a metal alkali or an organic hydroxide. It is believed that the source of hydroxyl ions functions as a hydration suppressant for the yttria to prevent premature gelation of the slurry. The slurry contains a silicon oxide (SiO.sub.2) to alkali ratio which is equivalent to a silicon oxide to sodium oxide (Na.sub.2 O) dry weight ratio of less than thirty-to-one (30:1).
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.