| 摘要 |
PURPOSE:To simply and effectively prevent the grain boundary damage of an Ni alloy brought into contact with a degassed alkali soln. at high temp., by adding a specified amt. of a sludge dispersing agent consisting of polycarboxyalkylphosphinic acid and a salt thereof to the degassed alkali soln. at high temp. CONSTITUTION:A sludge dispersing agent consisting of polycarboxyalkylphosphinic acid and/or one or more kinds of salts thereof is added to a degassed alkali soln. at high temp. by 0.3-300ppm basing on the amt. of the soln. Cyclic amine is further added by 0.3-300ppm as required. Bis(poly-2-carboxyethyl)phosphinic acid or bis(poly-2-carboxypropyl)phosphinic acid is especially suitable for use as the polycarboxyalkylphosphinic acid and morpholine or quinoline is especially suitable for use as the cyclic amine. The sludge dispersing agent disperses Fe3O4, Cu, Cu2O, CuO, etc., and prevents the deposition of them in the alkali soln., so the grain boundary damage of an Ni alloy brought into contact with the soln. is prevented.
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