Copper................ 70.00
Manganese............. 15.00
Zinc.................. 15.00
But as this alloy often breaks in rolling, the preference is given to
the following proportions:
Copper................ 80.00
Manganese............. 15.00
Zinc.................. 5.00
This results in a white, ductile metal, which is easily worked and
susceptible of receiving a beautiful polish, like the alloys of
nickel, which it may in time completely replace.
The _bronzes of manganese, tin, and zinc_ were perhaps the first upon
which important investigations were made; they were obtained by adding
to an alloy of copper, zinc, and tin (ordinary bronze) a definite
quantity of the cupro-manganese of the type indicated above (Cu 70, Mn
30). By this means the resistance is increased fully nine per cent.,
probably in the same way as the copper, that is, by the deoxidizing
effect of the manganese, as both the copper and the tin are always
more or less oxidized in ordinary bronzes.
Manganese combines with tin just the same as it does with copper, and
the proportion which is recommended as giving the highest resistances
is three to six per cent. of cupro-manganese.
However, notwithstanding the use of cupro-manganese, the tin, as in
ordinary bronzes, has a tendency to liquate in those portions of the
mould which are the hottest, and which become solid the last,
especially in the case of moulds having a great width.
From a series of experiments made at Isabelle Hütte, it has been found
that the metal which has the greatest resisting qualities was obtained
from
Copper......................85.00
Manganese................... 6.00
Zinc........................ 5.00
5 per cent. of cupro-manganese = manganese 1.00 remaining in the
metal.
The best method of procedure is first to melt the copper in a
crucible, and then to add the tin and the zinc; finally the
cupro-manganese is added just at the moment of pouring, as in the
Manhès process; then the reaction on the oxides is very effective,
there is a boiling with scintillation similar to the action produced
in the Bessemer and Martin process when ferro-manganese is added to
the bath of steel.
The following are some of the results obtained from thirteen alloys
obtained in this manner. These samples were taken direct from the
casting and were tested with the machine at Friedrich-Wilhelms-hütte,
and with the one at the shops of the Rhine Railroad. Their resistance
was considerably increased, as with the other alloys, by rolling or
hammering.
-------+------+------+-----+---------+---------+----------+--------+-------+
| | | | | | | Weight | |
| | | | | |Limit of | of | Elong-|
|Nature| | | | |elasticity|fracture| ation,|
| of | | | | Cupro- |in kilos |in kilos| per- |
Numbers|mould.|Copper| Tin.| Zinc. |manganese|per mm. | per mm.|centage|
-------+------+------+-----+---------+---------+----------+--------+-------+
1 | Sand | 85.00| 6.00| 5.00 | | 11.30 | 16.00 | -- |
2 | -- | 85.00| 6.00| 5.00 | 4.00 | 13.00 | 16.10 | 2.00 |
3 | Cast.| 87.00| 8.70| 4.30 | 4.00 | -- | 19.40 | -- |
4 | -- | 85.00| 6.90| 5.00 | 6.00 | -- | 18.80 | 6.00 |
5 | -- | 85.00| 6.00| 5.00 | 6.00 | -- | 19.75 | 7.00 |
6 | -- | 85.00| 6.00| 5.00 | 10.00 | -- | 17.15 | 4.00 |
7 | Sand | 87.00| 5.20| 4.33 | 3.47 | -- | 19.70 | 8.70 |
8 | -- | 87.00| 5.20| 4.33 | 3.47 | -- | 19.70 | 8.90 |
9 | -- | 85.00| 6.00| 5.00 | 3.00 | 16.80 | 22.00 | -- |
10 | -- | 74.00|10.00| 5.00 | 3.30 | 13.80 | 18.70 | -- |
| | | |(7.66 Pb)| | | | |
11 | -- | 78.70| 8.00| ( 8 Pb) | 3.30 | 13.80 | 20.70 | -- |
12 | -- | 82.00| 9.80| 4.90 | 3.30 | 14.75 | 19.75 | -- |
13 | -- | 86.20|16.50| -- | 3.30 | 14.30 | 24.70 | -- |
-------+------+------+-----+---------+---------+----------+--------+-------+
The results of the tests of ductility which are here given, with
reference to the _cupro-manganese_, _manganese bronze_, the _alloys_
with _zinc_ and _tin_, are taken from M.C. Hensler's very valuable
communication to the Berlin Society for the Advancement of the
Industrial Arts.
These various alloys, as well as the _phosphorus bronze_, of which we
make no mention here, are at present very largely used in the
manufacture of technical machines, as well as for supports, valves,
stuffing-boxes, screws, bolts, etc., which require the properties of
resistance and durability. They vastly surpass in these qualities the
brass and like compounds which have been used hitherto for these
purposes.--_Bull. Soc. Chim., Paris_, xxxvi. p. 184.
* * * * *