Removal of niobium second phase particle deposits from pickled zirconium-niobium alloys
View Patent ↗The present invention relates generally to a process and chemical composition for the removal of adherent niobium-rich second-phase particles (SPPs) from pickled niobium-containing zirconium alloys which includes applying to the alloy surface a chemical composition comprising alkaline hydrogen peroxide; an alkali metal meta-silicate; and a magnesium salt.
1. A smut removal composition, consisting of:
3 to 30 weight percent of hydrogen peroxide based on a total weight of the composition;
2 to 12 weight percent of an alkali metal meta-silicate based on a total weight of the composition;
0.2 to 1.0 weight percent of a magnesium salt based on a total weight of the composition;
a remainder weight percent of water based on a total weight of the composition; and
a pH value in the range of from 10.0 to 10.7.
2. The smut removal composition of claim 1 wherein the alkali metal meta-silicate is selected from the group consisting of sodium meta-silicate and potassium meta-silicate.
3. The smut removal composition of claim 1 wherein the magnesium salt is selected from a group consisting of magnesium sulfate and magnesium nitrate.
4. The smut removal composition of claim 1 wherein the smut removal composition is in a form of a gel.
5. The smut removal composition of claim 2 wherein the alkali metal meta-silicate is sodium meta-silicate.
6. The smut removal composition of claim 3 wherein the magnesium salt is magnesium sulfate.