A method of impregnating a porous article with impregnant to seal the pores thereof, which comprises placing the article in a vessel, evacuating the vessel to withdraw air from the pores, releasing the vacuum with the pores beneath the surface of a liquid impregnant in the vessel, removing excess impregnant from the vessel, washing excess impregnant from the surface of the article by supplying washing fluid to the vessel, removing the fluid from the vessel, heating the article while still within the vessel to effect curing of the impregnant within the pores, and removing the impregnated article from the vessel.
In a conventional method of impregnating die-cast articles, the sealing property is not excellent due to air being dragged into the sealant. In the present invention, the dragging of air into the sealant is prevented by adjusting the pressure of the sealant storage vessel and the pressure of the impregnation vessel to substantially the same level and then flowing the sealant from the sealant storage vessel into the impregnation vessel. After impregnation, the sealant reenters the sealant storage vessel, and pressure is applied to the die-cast articles so as to remove excessive sealant from them.
An apparatus (2) for the impregnation of metal castings including an impregnation chamber (11) having an open end; a movable assembly (2) comprising a cover (20) for closing the open end of the impregnation chamber, a casting carrier (21), carrier transport means (22) for raising and lowering the casting carrier relative to the cover, and carrier rotating means (23); and transport means (24) for raising and lowering the movable assembly relative to the open end of the impregnation chamber. The impregnation chamber is partially filled with liquid sealant (30). The apparatus is operated to position the carrier in the impregnation chamber above the liquid sealant therein and develop a vacuum in the chamber, submerge the carrier (and castings therein) in the sealant, and then raise the carrier above the sealant level and rotate carrier to spin-off excess liquid sealant; the movable assembly is thereafter raised to unload impregnated castings.
A pressure vessel for use in impregnating porous articles comprising a support member for the articles, slidable between an upper position for degassing the articles and a lower position for impregnating the articles, a release mechanism operable from outside the pressure vessel to permit the support member to descend from the upper position to the lower position under gravity, and damping means at least partially within the pressure vessel for controlling descent of the support member.
There is provided a method and apparatus for impregnating carbon articles with hot impregnating medium in a closed autoclave whereby the articles to be impregnated are introduced into the autoclave which is then closed and heated by means of a heat exchanger to the impregnating temperature at which point the impregnating medium is introduced to fill the autoclave and then pressurized to impregnate the articles. Subsequent to impregnation, the impregnating medium is removed from the autoclave and the closed or sealed autoclave and the impregnated articles are cooled to a temperature below a predetermined "lower limit temperature" and the articles are then removed from the autoclave. The "lower limit temperature" is chosen to eliminate the emission of harmful off-gases.
A method of sealing a porous heating or cooling jacket of a reactor vessel includes the steps of: (a) draining the heating or cooling fluid from jacket; (b) washing and drying the interior of the jacket; (c) filling the jacket with a curable liquid sealant composition under pressure sufficient to cause the composition to permeate the porous areas in the jacket but insufficient to burst the jacket, the composition being curable at temperatures between about 75.degree. C. and 100.degree. C.; (d) draining the sealant from the jacket; and (e) heating the jacket to or above the cure temperature of the composition and maintaining that temperature for sufficient time to ensure total polymerization of the reactant composition.
