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).
Wear of anodic coatings on R.R. 53 pistons and suggesting improvements.
| Identifier | ExFiles\Box 87\2\ scan0005 | |
| Date | 3rd January 1935 | |
| To Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} c.c. Wor.{Arthur Wormald - General Works Manager} c.c. BY.{R.W. Bailey - Chief Engineer} HLL/AG.3.1.35. Laboratory. Re: Anodic Oxidation of R.R. 53 Pistons. This is to confirm our conversation this morning in reply to yours Hs{Lord Ernest Hives - Chair}/Rm{William Robotham - Chief Engineer}4/KW.14.12.34. We note that the coating on the two Bentley Pistons anodically oxidised by us has worn through in places after 10 hours running on the test bed. This coating was approximately 0.0003" thick and consequently we think that presuming we could increase a coating of this nature to twice this thickness by the use of higher potential, we would not anticipate that the coating would last for hundreds of hours. It does not appear to be clearly established that the anodic coating is necessary throughout the whole life of the Piston and we suggest that it would be interesting to run a test, with a coating as before, for a considerable period, under conditions normally tending towards "pick-up", to see, if the anodic coating will function during the "running in" period of new cylinder/Pistons, whether pick up will occur subsequently when the coating has worn through. We have two other suggestions to make. First, using a coating as before, but stiffened up by impregnation, to ascertain whether we can reduce the wear on the coating by this means without impairing its efficiency. Secondly, we suggest that the efficiency of the anodic coat as previously tested, may be due to the retention of oil by adsorption, thus never allowing the Piston to come into dry contact with the cylinder wall during the life of the coating. If this is so, then we think that a light, fine, etch on the piston surface might serve a similar purpose, holding the oil by capillary attraction and possibly reducing the liability to scoring due to particles of wear product etc. being trapped between piston and cylinder wall. contd. | ||