Patent ID: 6770333
Filing Date: 2004-08-03
Classification: C23C

Abstract:
A method of operating an electron beam physical vapor deposition coating apparatus, the method comprising the steps of:performing a first coating operation during which: at least a first article is placed in a coating chamber in which a gas-containing atmosphere is contained, the gas-containing atmosphere being at a first temperature and at a subatmospheric pressure; and an electron beam gun is operated to project an electron beam into the coating chamber and onto a ceramic material, the electron beam heating, melting and evaporating the ceramic material to deposit a ceramic coating on the first article; wherein combined heat transfer to the first article from sources other than the gas-containing atmosphere within the coating chamber occurs at a first heat transfer rate while the first article is within the coating chamber, so that a surface temperature of the first article does not exceed about 1000Â° C. during deposition of the ceramic coating on the first article; and subsequently performing a second coating operation during which: at least a second article is placed in the coating chamber while the gas-containing atmosphere within the coating chamber is at a subatmospheric pressure and at a second temperature that is higher than the first temperature; and the electron beam gun is operated to project the electron beam into the coating chamber and onto the ceramic material to heat, melt and evaporate the ceramic material and deposit a ceramic coating on the second article; wherein combined heat transfer to the second article from sources other than the gas-containing atmosphere within the coating chamber occurs at a second heat transfer rate that is lower than the first heat transfer rate while the second article is within the coating chamber, so that a surface temperature of the second article does not exceed about 1000Â° C. during deposition of the ceramic coating on the second article.