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).
Technical discussion on tungsten oxides in relation to current density and criticisms of ignition break mechanisms.
| Identifier | ExFiles\Box 37\1\ scan 044 | |
| Date | 26th April 1917 | |
| BY7/P61218. -3- Contd. His contention was that if the current density was kept within certain definite limits that the tungsten formed an oxide which was a good conductor and which prevented further oxidation for any transference of material from one point to the other. If the current density rose above the maximum fixed then a second oxide of tungsten was formed which was a non-conductor, and which did not adhere to the tungsten itself but crumbled away. He stated that the requirements of battery ignition were such as to come within the limit of current density under which tungsten terminal would form a lower oxide which adhered strongly to its parent material and was a good conductor. (2) In criticising our break mechanism for the low tension circuit he thought that the flexible spring, when pressed upon by the breaker, would cause sliding on the tungsten terminal, this he stated, was undesirable. It seems to me quite probable that sliding would be beneficial on a platinum terminal if the movement was very slight, but in the case of tungsten, as defined above, it might have the opposite effect, since apparently the tungsten is not transferred, does not pit, and therefore would not wear away except it had some sliding movement to wear it. (3) He was quite emphatic in regard to the fact that the revolving brush, or spark point on the high tension, would require controlling endways. He based this criticism upon the fact that it had been proved to be necessary in the Liberty scheme. He could not give me any definite reason why the brush in question should move in one direction or the other, but stated in several cases the brush had tended to move and the spring on the central Contd. (Upside down text) R.R. 235A (500) (S.D. 408. 26.4.17.) B'm.{Mr Moon / Mr Moore} 2/156/13. | ||