Proportion quantitative analysis and etching of {110} planes on tungsten single crystal coating surface

• Tungsten single/poly crystals treated by electrolytic etching in solution of NaOH.
• The {110} planes have the lower surface free energy than {112}.
• Some {112} planes etched firstly, the {110} planes exposed at last during etching.
• {110} planes exposed to the greatest extent with 1.4 amp/cm2 and 3 min.

Tungsten single crystal and poly crystal were treated by electrolytic etching in a 3% by weight solution of NaOH in distilled water. The method for determining the proportion of {110} planes and characteristic morphology on the coating surface after electrolytic etching were investigated using EBSD and auto-focusing microscope. Then the optimization of process parameters for electrolytic etching is achieved. In order to compare the effect of process parameters, three process parameters were selected for the tungsten single crystal electrolytic etching. Through analyzing the change of {110} planes' proportion, we found that when the coatings are etched with 1.4 amp/cm2 and 3 min, {110} planes can be exposed in the greatest degree that can reach 61.4% on tubular surfaces. The proposed approach greatly improves the proportion of {110} planes relative to the original surface.

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