Method for making self-protecting carbon bodies
US4591514A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Feb 13, 1985 |
| Grant date | May 27, 1986 |
| Priority date | — |
| Expiry date | Feb 13, 2005 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC04B41/89
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
A method of forming a coated article is described. The article is composed of a carbon body having a thermochemically deposited coating which renders the body resistant to oxidation at high temperatures. A volatile gaseous halide of silicon is partially reduced to form a lower halide in a first reaction zone having a first pressure and separated from the body. The lower halide is flowed into a second reaction zone maintained at a pressure lower than the pressure in the first reaction zone. A gaseous alloying agent is introduced into the second reaction zone. The agent includes one or more elements selected from the group consisting of carbon, oxygen, aluminum, and nitrogen. As a consequence, a liquid phase intermediate compound is deposited on the substrate body which is thereafter thermochemically reacted to produce a coating of the silicon alloy. The coating has a non-columnar grain distribution with substantially equiaxial grains of an average diameter of less than one micron and forms a correspondingly fine crack mosaic upon stressing due to differences in thermal coefficients of expansion between the coating and the body. The lower halide and the alloying agent are controlled …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.