Precision silica cones for sand casting of steel and iron alloys
US4352390A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Sep 12, 1980 |
| Grant date | Oct 5, 1982 |
| Priority date | — |
| Expiry date | Sep 12, 2000 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC03B20/00
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
Partially devitrified silica cores with exceptional high temperature strength are disclosed for foundry use in sand casting of ferrous alloys. Precision cored holes of small size and long length, which heretofore could not be cast accurately or had to be machined because of limitations in existing core technology, are formed using accurately machined extruded porous silica cores fired to eliminate combustibles and partially devitrified (e.g., 15 to 30%) to develop a strong crystalline phase bond that resists viscous flow at a temperature of 1500.degree. C. and to increase the refractoriness of the vitreous silica grains, whereby the permeability and thermal shock resistance are such that the core can be heated very rapidly by molten steel to above 1500.degree. C. without spalling, cracking, sagging, breaking, or loss of integrity and without gas holes, scabs, fissures or other serious casting defects. The cores are made from an extrudable composition containing vitreous silica, a mineralizer, an organic binder, and a plasticizer and/or tempering fluid. High-purity vitreous silica grains are mixed with a mineralizer and large amounts of finer vitreous silica particles (e.g., below 1…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.