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).
Comparison of chromium plating with nitrogen hardening, discussing issues of hardness, adherence, and cracking.
| Identifier | ExFiles\Box 30\6\ Scan063 | |
| Date | 22th November 1928 | |
| ROYCE LTD. c. HS.{Lord Ernest Hives - Chair} X1360 BY11/G.22.11.28. CHROMIUM PLATING. ----------------- We do not consider so far as our knowledge goes at the moment that the hardness obtained by chromium plating is either :- a/- As intensely or b/- As well supported as the hardness obtained by nitrogen hardening in the special steels produced for this purpose. Chromium plating, whilst admittedly very hard is only that of comparatively lightly adherent to its base material. Whilst it may be considered to be partially alloyed, inasmuch as the adherence is a positive factor, it does not reach into the structure of the steel in the way that the nitrogen hardened case does. One further difficulty is that the deposited coating of chromium must be thin, otherwise there is a great tendency for same to crack as the chromium is necessarily brittle, and unless the base to which it is fixed is rigid, cracking is almost certain to take place. Further if an attempt is made to deposit a greater thickness, and to grind to size, then chromium exhibits difficulties from the point of view of grinding. Great care has to be used or again cracking takes place. For wearing surfaces it is generally deposited thin, and is not as reliable from a wear point of view as the nitro alloy hardened skin. BY.{R.W. Bailey - Chief Engineer} [Signature] | ||