From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Conclusions on the effectiveness of platinum, palladium, or rhodium coatings on nickel electrodes to delay erosion.
| Identifier | ExFiles\Box 58\2\ Scan169 | |
| Date | 1st November 1933 guessed | |
| 4. E&I.818. coated electrode shows an amount of erosion nearly twice that of the standard material. These two tests show that coating the electrodes with either palladium or rhodium is of no practical value in relation to the normal life of a plug. The attached photograph shows the condition of the plug electrodes after the 601/4 hours test. 6. Conclusions. (a) Coatings of platinum, palladium or rhodium on nickel electrodes delay the onset of measurable erosion for a few hours only; thereafter, erosion proceeds at approximately the same rate as an uncoated electrode. (b) Microscopic examination of a platinum coated electrode during laboratory tests showed that penetration of the protective coating occurred within 7 to 10 hours. (c) The tests show generally that thin deposits of the metals in question are of no practical value; the period during which they exercise a delaying action on erosion is insignificant in relation to the total life of a sparking plug. Attached:- Photograph No.16079, Fig.3. Drawing No.E&I.4965, Figs.1 and 2. | ||