Ti6Al4V alloy interacted with yttria fully stabilized zirconia face-coat to generate the alpha-case layer during the investment casting. The alpha-case mainly contained Al2O3, TiO2, TiO0.48, VO2, ZrO2 and Ti2ZrAl as revealed by the Energy dispersive X-ray and X-ray diffraction analyses. The chemical milling of this outer layer, using a mixture of hydrofluoric acid and nitric acid, removed contaminating phases and led to lower hardness of the free surface of the investment casting. The roughness as well as the glossiness of the chemically milled surface decrease as the hydrofluoric acid concentration decreases. Mixing the hydrofluoric acid with phosphoric acid affects the surface morphology.
Reference:
Mutombo, K and Rossouw, P. Effect of pickling solution on the surface morphology of Ti6Al4V alloy investment cast. Titanium 2011, Sheraton San Diego Hotel & Marina, San Diego, California, 2-5 October 2011
Mutombo, K., & Rossouw, P. (2011). Effect of pickling solution on the surface morphology of Ti6Al4V alloy investment cast. International Titanium Association. http://hdl.handle.net/10204/5628
Mutombo, K, and P Rossouw. "Effect of pickling solution on the surface morphology of Ti6Al4V alloy investment cast." (2011): http://hdl.handle.net/10204/5628
Mutombo K, Rossouw P, Effect of pickling solution on the surface morphology of Ti6Al4V alloy investment cast; International Titanium Association; 2011. http://hdl.handle.net/10204/5628 .