Coating temperature during vapor deposition of a ceramic coating on a substrate in a coating box or enclosure is maintained by means of a heat release cover or lid on the coating enclosure and movable in response to temperature in the coating enclosure exceeding a predetermined value so as to release excess heat from the enclosure to maintain coating temperature within an appropriate range.
An electron beam physical vapor deposition (EBPVD) apparatus and a method for using the apparatus to produce a coating material (e.g., a ceramic thermal barrier coating) on an article. The EBPVD apparatus generally includes a coating chamber that is operable at elevated temperatures and subatmospheric pressures. An electron beam gun projects an electron beam into the coating chamber and onto a coating material within the chamber, causing the coating material to melt and evaporate. An article is supported within the coating chamber so that vapors of the coating material deposit on the article. The operation of the EBPVD apparatus is enhanced by the inclusion or adaptation of one or more mechanical and/or process modifications, including those necessary or beneficial when operating the apparatus at coating pressures above 0.010 mbar.
An electron beam physical vapor deposition (EBPVD) apparatus for producing a coating material (e.g., a ceramic thermal barrier coating) on an article. The EBPVD apparatus generally includes a coating chamber that is operable at elevated temperatures and subatmospheric pressures. An electron beam gun projects an electron beam into the coating chamber through an aperture in a wall of the chamber and onto a coating material within a coating region defined within the chamber, causing the coating material to melt and evaporate. An article is supported within the coating chamber so that vapors of the coating material deposit on the article. The operation of the EBPVD apparatus is enhanced by the inclusion within the coating chamber of a second chamber that encloses the aperture so as to separate the aperture from the coating region. The second chamber is maintained at a pressure lower than the coating region.
A method of operating an EBPVD apparatus (10) to deposit a ceramic coating on an article (20), such that the thermal conductivity of the coating is both minimized and stabilized. More particularly, the EBPVD apparatus (10) is operated to perform multiple successive coating operations which together constitute a coating campaign. During the campaign, the surface temperatures of the articles (20) being coated do not exceed about 1000.degree. C. as a result of the combined heat transfer from the coating chamber (14) to the articles (20) being reduced during the course of the campaign, even though the temperature within the coating chamber (14) continuously rises during successive coating operations of the campaign. Ceramic coatings deposited at such relatively low temperatures exhibit lower and more stable thermal conductivities.
Rapid thermal cycling of substrates in low-pressure processing environments is achieved by movable temperature conditioners located outside the processing environments. The substrates are mounted on thermally conductive pedestals for processing in the low-pressure environment. The temperature conditioners are movable both into and out of thermal contact with the pedestals outside the low-pressure environment to regulate transfers of heat through the pedestals between the substrates and the temperature conditioners. A translatable cooler block with a high thermal mass and a large interface area with the pedestal can be used as a temperature conditioner for more rapidly withdrawing heat from the substrate.