Abstract
In these days, boriding of metals and alloys has been studied for improving their wear, corrosion, and oxidation resistances.
There are four methods of boriding; solid, liquid, gaseus, and electrolytic boridings. The elect-rolytic boriding is mainly researched among them, because it gives a thick and dense borided layer at lower temperatures in a shorter period, as compared with other methods. The electrolytic boriding of tungsten was studied in order to improve its wear and oxidation resistances.
This paper describes the relation between the boriding conditions and borided layer in electrolytic boriding of tungsten using a molten borax bath.
The results of studies were as follows:
(1) The borided layer consisted of two borides, W2B5 and WB. The latter layer was thicker than that of the former in these experiments.
(2) The preferable conditions of the boriding were as follows: the current density was 0.2-0.3Amp/cm2 and the addition of B2O3 to the borax bath was 20-25%.
A layer of about 50μ in thickness was obtained at 900°C for 2hrs. under the above conditions.
(3) The effects of contamination on the borided layer by dissolution of Fe, Cr, Ni, etc. from the crucible and anode materials were remarkable; care must be taken to prevent it from these contaminations.
