Transparent non-vitreous zirconia microspheres
US4772511A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 22, 1985 |
| Grant date | Sep 20, 1988 |
| Priority date | — |
| Expiry date | Nov 22, 2005 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T428/2982
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
Solid, transparent, non-vitreous, zirconia and zirconia-silica ceramic microspheres, useful as lens elements in retroreflective pavement markings. The microspheres are characterized by: PA1 (a) containing at least one additive metal oxide selected from alumina, magnesia, yttria and mixtures thereof; PA1 (b) an index of refraction greater than 1.6; and PA1 (c) being virtually free of cracks. These microspheres are formed by a sol-gel technique of extractive gelation (extracting carboxylic acid away from zirconyl carboxylate) of a sol in liquid medium such as hot peanut oil. The microspheres of this ceramic composition have been made with relatively large diameters, (e.g. 200-1000 micrometers) making them quite useful as lens elements in pavement marking sheet materials.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.