Platinised Titanium and Niobium anodes are used as insoluble anodes in modern electroplating baths for hard chromium plating of rotogravure cylinders and piston rings, etc. Chrome acid solutions, which contain sulphuric acid, are used as electrolyte.
For hard chromium plating of rotogravure cylinders or piston rings – semi-circular, anodes very well adapt to the cylinder shape cathodes. In principle, different types of anodes are used with one or two bows.
The platinum layer is produced of molten platinum salt by means of the procedure up to 20 micron thickness.
The platinised titanium or platinised niobium (if the bath contains higher rate of fluorides), will perform: dense crystalline layer structure and thereby good mechanical properties; even metal distribution of the platinum layer and optional adhesion of the Ti mesh; long lasting (approx 8 g platinum per 1 million Ah are removed per bath) and dimensionally stable; the base material or substrate is reusable after re-plating; no maintenance of anodes necessary; constant conductivity of the anodes; and very short distance from the electrode to the articles (cylinder – 4-6 cm)..