Supercritical fluid molecular spray thin films and fine powders
US4734451A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Mar 12, 1986 |
| Grant date | Mar 29, 1988 |
| Priority date | — |
| Expiry date | Mar 12, 2006 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB05D2401/90
- WIPO fieldSurface technology, coating
- WIPO sectorChemistry
Abstract
Solid films are deposited, or fine powders formed, by dissolving a solid material into a supercritical fluid solution at an elevated pressure and then rapidly expanding the solution through a short orifice into a region of relatively low pressure. This produces a molecular spray which is directed against a substrate to deposit a solid thin film thereon, or discharged into a collection chamber to collect a fine powder. The solvent is vaporized and pumped away. Solution pressure is varied to determine, together with flow rate, the rate of deposition and to control in part whether a film or powder is produced and the granularity of each. Solution temperature is varied in relation to formation of a two-phase system during expansion to control porosity of the film or powder. A wide variety of film textures and powder shapes are produced of both organic and inorganic compounds. Films are produced with regular textural feature dimensions of 1.0-2.0 .mu.m down to a range of 0.01 to 0.1 .mu.m. Powders are formed in very narrow size distributions, with average sizes in the range of 0.02 to 5 .mu.m.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.