Removing coating contg. aluminium, chromium and cobalt - from nickel alloy substrate using aq. soln. contg. iron sulphate and hydrogen chloride

摘要

Removal of an Al-, Cr- and Co-contg. coating from a Ni alloy-based substrate takes place by immersing the coated substrate in an etching soln. contg., by wt., 6-14 (8-10) esp. 10% FeSO4, 3.5-11 (7-9) esp. 7.2% HCl, bal. water. Process is partic. suitable for turbine blades, to etch off coating for renewal or for testing substrate, e.g. for small, hidden cracks. An adequate dissolution rate of coating is achieved with min. attack of substrate. Etching soln. is pref. kept at 15-75 (45-55) degrees C.