System and method for plasma coating
US4328257A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 26, 1979 |
| Grant date | May 4, 1982 |
| Priority date | — |
| Expiry date | Nov 26, 1999 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC23C4/137
- WIPO fieldChemical engineering
- WIPO sectorChemistry
Abstract
Uniform protective coatings are deposited on components with a high strength bond by utilizing a supersonic plasma stream and a transferred arc system of selectively reversible polarity. By maintaining plasma stream velocity at a sufficiently high Mach number, and using stream temperatures and static pressures which establish a shock pattern characteristic that diffuses the arc, the workpiece is made cathodic relative to the plasma gun at predetermined intervals. This creates a sputtering effect in which electrons and atoms are ejected from the workpiece despite the impacting plasma flow and the ambient pressure level. This sputtering action is undertaken to clean the workpiece once it is sufficiently heated and to cause intermingling of molecules of the substrate material with molecules of a deposition powder injected into the plasma flow. This preparatory deposition, together with the clean workpiece surface, enables a subsequent buildup of securely bonded and high uniform material.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.