Patent ID: 7927656

Claim:
A method of depositing first and second diffusion coatings on first and second surface portions of at least one internal passage within a component, the method comprising: providing a retort that comprises an interior, an inlet and an outlet to the interior, a coating chamber within the interior, first and second conduits within the interior and coupled to the coating chamber, a first shuttle valve within the interior and fluidically connected to the coating chamber through the first conduit, and a second shuttle valve within the interior and fluidically connected to the coating chamber through the second conduit; placing the component within the coating chamber so that the first conduit fluidically communicates with at least a first opening in the component and the second conduit fluidically communicates with at least a second opening in the component; heating the retort so as to heat the coating chamber, the first and second conduits, the first and second shuttle valves, and the component within the coating chamber; generating first and second reactive vapors within the coating chamber; delivering a carrier gas through the first shuttle valve, through the first conduit and then into the coating chamber to force a quantity of the first reactive vapor to enter the internal passage through at least the first opening in the component, flow through the internal passage in a first direction, exit the component through at least the second opening in the component, flow through the second conduit to the second shuttle valve, and vent into the interior of the retort through the second shuttle valve, wherein the first reactive vapor forms the first diffusion coating on the first surface portion of the internal passage as the first reactive vapor flows therethrough; and then delivering the carrier gas through the second shuttle valve, through the second conduit and then into the coating chamber to force a quantity of the second reactive vapor to enter the internal passage through at least the second opening in the component, flow through the internal passage in a second direction opposite the first direction, exit the component through at least the first opening in the component, flow through the first conduit to the first shuttle valve, and vent into the interior of the retort through the first shuttle valve, wherein the second reactive vapor forms the second diffusion coating on the second surface portion of the internal passage as the second reactive vapor flows therethrough; and flowing a gas through the inlet of the retort and removing the gas through the outlet of the retort to purge the interior of the retort of the first and second reactive vapors vented into the interior through the first and second shuttle valves.