| 摘要 |
A method of making preforms from brittle metals for brazing or hardfacing consists of pulverizing the metals into a powder, mixing the powder with a liquid vehicle to form a paste, passing the paste through a coated screen having an opening in the coating with the size and shape of the desired preform, depositing the output of the screen onto a substrate and thereby making the preform, heating the preform to evaporate the liquid vehicle, and removing the preform from the substrate. The opening in the screen coating is made by exposing a photo-sensitive film to light through a photographic negative or similar mask having the image of the preform and chemically removing a portion of the film to form an opening having the shape of the preform, the film being mounted on the screen either before or after such exposure.
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