| 摘要 |
To prevent corrosion in subsequent high temperature exposure, backers for electron beam hole drilling of nickel base superalloys contain glass particulates of the borosilicate and aluminosilicate types, having an alkali metal oxide content of less than 1 weight percent and a heavy metal (Pb, Bi, Sn, Sb, As) content of less than 25 ppm. Preferably the binder is a soluble inorganic material, such as magnesium dichromate or a polymer, also free of alkali metal content.
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