1951 Volume 20 Issue 2 Pages 67-74
1. Borax-alkali binder is classified in Borax-NaHCO3, Borax-NaOH, and Borax-KOH.
2. Borax-alkali binder used as welding flux, of which the proportion is such that addition of 40CC. water gives proper coating, develops best binding action, when about 2 g. of NaOH is added to the oversaturated solution of borax; namely, when NaOH concentration is around 1.25N, orKOH concentration is around 1.16-1.25N.
3. Depending on the kinds and proportions of welding flux, the binder proves most effective, with NaOH addition of less than 2g., when added water is less than 40C C., or when the solution is saturated for borax.
4. The principle of binding is the same either with borax-NaOH or with borax-NaHCO3. As Na-OH volume in the solution of the latter is very small as compared with the former, it can be assumed that this difference in NaOH volume is balanced by hydrolysis of NaHCO3 which takes place to compensate the loss of NaOH required for crystalization and precipipitation of dissolved borax.