Testing of a Liga-Microspectrometer for Monitoring Dissolved Nickel Concentration When Etching Nickel and Its Alloys in Aqueous Ferric Chloride Solutions

In the photochemical machining of micro-parts from nickel-containing alloys, a solution of ferric chloride is used as the etchant. As the alloy is dissolved into solution, the concentration of dissolved nickel will increase to a point where the surface finish of the etched parts will be affected adversely and become rougher. To control part quality and reduce the number of defective parts, it y
is therefore necessary to monitor the build-up of nickel ions on-line. A miniature, commercial microspectrometer has been evaluated for its suitability to monitor the nickel concentration. The microspectrometer has been shown to be cost­effective and is capable of measuring the concentration of nickel ions to ± l g/1.