──────+────────+───────+──────+───────────────_Henley's Twentieth Century Formulas, Recipes and Processes

│ Copper │ Zinc │ Tin │ Color

──────+────────+───────+──────+───────────────

I │ 84.42 │ 11.28 │ 4.30 │ Reddish yellow

II │ 84.00 │ 11.00 │ 5.00 │ Orange red

III │ 83.05 │ 13.03 │ 3.92 │ Orange red

IV │ 83.00 │ 12.00 │ 5.00 │ Orange red

V │ 81.05 │ 15.32 │ 3.63 │ Orange yellow

VI │ 81.00 │ 15.00 │ 4.00 │ Orange yellow

VII │ 78.09 │ 18.47 │ 3.44 │ Orange yellow

VIII │ 73.58 │ 23.27 │ 3.15 │ Orange yellow

IX │ 73.00 │ 23.00 │ 4.00 │ Pale orange

X │ 70.36 │ 26.88 │ 2.76 │ Pale yellow

XI │ 70.00 │ 27.00 │ 3.00 │ Pale yellow

XII │ 65.95 │ 31.56 │ 2.49 │ Pale yellow

──────+────────+───────+──────+───────────────

{58}

Perhaps the most satisfactory bronze metal is the alloy used in France

for more than a century. It contains 91.60 per cent of copper, 5.33 per

cent of zinc, 1.70 per cent of tin, and 1.37 per cent of lead. Somewhat

more zinc is taken for articles to be gilded.

«Bismuth Bronze.»—Copper, 52 parts; nickel, 30 parts; zinc, 12 parts;

lead, 5 parts; bismuth, 1 part. For metallic mirrors, lamp reflectors,

etc.

Gun Bronze.—See Phosphor Bronze under this title.

«Japanese Bronzes.»—The formulas given below contain a large percentage

of lead, which greatly improves the patina. The ingredients and the

ratio of their parts for several sorts of modern Japanese bronze follow:

I.—Copper, 81.62 per cent; tin, 4.61 per cent; lead, 10.21 per cent.

II.—Copper, 76.60 per cent; tin, 4.38 per cent; lead, 11.88 per cent;

zinc, 6.53 per cent.

III.—Copper, 88.55 per cent; tin, 2.42 per cent; lead, 4.72 per cent;

zinc, 3.20 per cent.

Sometimes a little antimony is added just before casting, and such a

composition would be represented more nearly by this formula:

IV.—Copper, 68.25 per cent; tin, 5.47 per cent; zinc, 8.88 per cent;

lead, 17.06 per cent; antimony, 0.34 per cent.

For imitation Japanese bronze, see Plating under Bronzing.

«Machine Bronze.»—I.—Copper, 89 per cent; tin, 11 per cent.

II.—Copper, 80 per cent; tin, 16 per cent.

«Phosphor Bronze.»—Phosphor bronze is bronze containing varying amounts

of phosphorus, from a few hundredths of 1 per cent to 1 or 2 per cent.

Bronze containing simply copper and tin is very liable to be defective

from the presence of oxygen, sulphur, or occluded gases. Oxygen causes

the metal to be spongy and weak. Sulphur and occluded gases cause

porosity. Oxygen gets into the metal by absorption from the air. It

can be eliminated by adding to the metal something which combines with

the oxygen and then fluxes off. Such deoxidizers are zinc, antimony,

aluminum, manganese, silicon, and phosphorus. Sulphur and occluded

gases can be eliminated by melting the metal, exposing it to the

air, and letting it thus absorb some oxygen, which then burns the

sulphur and gas. The oxygen can then be removed by adding one of the

above-mentioned deoxidizers. The important use of phosphorus in bronze

is, therefore, to remove oxygen and also indirectly to destroy occluded

gas and sulphur.

A bronze is sometimes made with an extra high percentage of phosphorus,

namely, 6 per cent. This alloy is made so as to have phosphorus in

convenient form for use, and the process of manufacture is as follows:

Ninety pounds of copper are melted under charcoal in a No. 70 crucible,

which holds about 200 pounds of metal when full; 11 pounds of tin are

added and the metal is allowed to become hot. The crucible is then

removed from the furnace and 7 pounds of phosphorus are introduced

in the following manner: A 3-gallon stone jar, half full of dilute

solution of blue vitriol, is weighed. Then the weights are increased 7

pounds, and phosphorus in sticks about 4 inches long is added till the

scales balance again. The phosphorus is left in this solution half an

hour or longer, the phosphorus being given a coating of copper, so that

it may be dried and exposed to the air without igniting. Have ready a

pan about 30 inches square and 6 inches deep, containing about 2 inches

of water. Over the water is a wire netting, which is laid loose on

ledges or supports along the inner sides of the pan. On the netting is

blotting paper, and on this the phosphorus is laid to dry when taken

out of the blue-vitriol solution. The pan also has a lid which can be

put down in case of ignition of the phosphorus.

The phosphorus is now ready for introduction into the metal. This

is done by means of a cup-shaped instrument called a retort or

phosphorizer. One man holds the retort on the rim of the crucible

in a horizontal position. A second man takes about three pieces

of phosphorus and throws them into the retort. The first man then

immediately plunges the mouth of the retort below the surface of the

metal before the phosphorus has a chance to fall or flow out. Of course

the phosphorus immediately melts and also begins to volatilize. As the

phosphorus comes in contact with the metal, it combines with it. This

process is continued till all the 7 pounds of phosphorus has been put

into the metal. The metal is then poured into slabs about 3 inches by 4

inches by 1 inch thick. The metal is so hard that a greater thickness

would make it difficult to break it up. When finished, the metal

contains, by analysis, 6 per cent of phosphorus. When phosphorus is to

be added to metal, a little of this hardener is employed.

Copper is a soft, ductile metal, with its melting point at about

2,000° F. {59} Molten copper has the marked property of absorbing

various gases. It is for this reason that it is so difficult to make

sound castings of clear copper. Molten copper combines readily with

the oxygen of the air, forming oxide of copper, which dissolves in the

copper and mixes homogeneously with it.

A casting made from such metal would be very spongy. The bad effect of

oxygen is intended to be overcome by adding zinc to the extent of 1

per cent or more. This result can be much more effectively attained

by the use of aluminum, manganese, or phosphorus. The action of these

substances is to combine with the oxygen, and as the product formed

separates and goes to the surface, the metal is left in a sound

condition. Aluminum and manganese deoxidize copper and bronze very

effectively, and the oxide formed goes to the surface as a scum. When a

casting is made from such metal, the oxide or scum, instead of freeing

itself from the casting perfectly, generally remains in the top part

of the casting mixed with the metal, as a fractured surface will show.

Phosphorus deoxidizes copper, and the oxide formed leaves the metal

in the form of a gas, so that a casting made from such metal shows a

clean fracture throughout, although the metal is not so dense as when

aluminum or manganese is used.

Copper also has the property of absorbing or occluding carbon monoxide.

But the carbonic oxide thus absorbed is in a different condition from

the oxygen absorbed. When oxygen is absorbed by copper, the oxygen

combines chemically with the copper and loses its own identity as

a gas. But when coal gas is absorbed by the copper, it keeps its

own physical identity and simply exists in the copper in a state of

solution. All natural waters, such as lake water, river water, spring

water, etc., contain air in solution or occlusion. When such water is

cooled and frozen, just at the time of changing from the liquid to the

solid state, the dissolved gas separates and forms air bubbles, which

remain entangled in the ice. The carbonic oxide which is dissolved or

occluded in copper acts in exactly the same way.

Hydrogen acts in exactly the same manner as carbonic oxide. Sulphur

also has a bad effect upon copper and bronze. Sulphur combines with

copper and other metals, forming sulphide of copper, etc. When

molten copper or bronze containing sulphur comes in contact with air

it absorbs some oxygen, and this in turn combines with the sulphur

present, forming sulphur dioxide, which is a gas which remains occluded

in the metal.

Tin is a soft, white metal, melting at 440° F. Toward gases it acts

something like copper, but not in so marked a degree. Although copper

and tin are both soft, yet when mixed they make a harder metal. When

bronze cools from the molten state, the copper and the copper-tin alloy

tend to crystallize by themselves. The quicker the cooling occurs the

less separation will there be, and also the fracture will be more

homogeneous in appearance.

Gun bronze contains copper and tin in the proportion of 9 or 10 parts

of copper to 1 of tin. This is the metal used when an ordinary bronze

casting is wanted. A harder bronze is copper and tin in the ratio of

6 to 1. This is often used as a bearing metal. When either of these

metals is to be turned in the machine shop, they should contain about

3 per cent of lead, which will make them work very much better, but

it also decreases their tensile strength. Bearing metal now generally

contains about 10 per cent of lead, with copper and tin in varying

ratios. The large percentage of lead is put in that the metal may wear

away slower. Lead, although a metal having properties similar to tin,

acts entirely different toward copper. Copper and tin have a good deal

of affinity for each other, but copper and lead show no attraction at

all for each other. Copper and tin mix in all proportions, but copper

and lead mix only to a very limited extent. About 3 per cent of lead

can be mixed with copper. With bronze about 15 per cent to 20 per

cent of lead can be mixed. In bearing bronze the lead keeps its own

physical properties, so that the constituent lead melts long before

the metal attains a red heat. It sometimes happens when a bearing runs

warm that the lead actually sweats out and forms pimples on the metal.

Or, sometimes, in remelting a bearing bronze casting the lead may be

seen to drop out while the metal is warming up. All of these metals,

however, should contain something to flux or deoxidize them, such as

zinc, manganese, aluminum, silicon, antimony, or phosphorus.

The phosphor bronze bearing metal in vogue has the following

composition: Copper, 79.7 per cent; tin, 10 per cent; lead, 10 percent;

and phosphorus, 0.3 per cent.

Melt 140 pounds of copper in a No. 70 pot, covering with charcoal. When

copper is all melted, add 17 1⁠/⁠2 pounds of tin to 17 1⁠/⁠2 pounds

of lead, and allow the metal to become sufficiently warm, but {60}

not any hotter than is needed. Then add 10 pounds of “hardener” (made

as previously described) and stir well. Remove from furnace, skim off

the charcoal, cool the metal with gates to as low a temperature as is

consistent with getting a good casting, stir well again, and pour. The

molds for this kind of work are faced with plumbago.

There are several firms that make phosphor-bronze bearings with a

composition similar to the above one, and most of them, or perhaps all,

make it by melting the metals and then charging with phosphorus to the

extent of 0.7 to 1 per cent. But some metal from all brands contains

occluded gas. So that after such metal is cast (in about two minutes

or so) the metal will ooze or sweat out through the gate, and such a

casting will be found to be porous. But not one such experience with

metal made as described above has yet been found.

This practical point should be heeded, viz., that pig phosphor bronze

should be brought to the specifications that the metal should have

shrunk in the ingot mold in cooling, as shown by the concave surface

of the upper side, and that it should make a casting in a sand mold

without rising in the gate after being poured.

In bearing metal, occluded gas is very objectionable, because the gas,

in trying to free itself, shoves the very hard copper-tin compound

(which has a low melting point and remains liquid after the copper has

begun to set) into spots, and thus causes hard spots in the metal.

Phosphorus is very dangerous to handle, and there is great risk from

fire with it, so that many would not care to handle the phosphorus

itself. But phosphor copper containing 5 per cent of phosphorus, and

phosphor tin containing 2 to 7 per cent of phosphorus, and several

other such alloys can be obtained in the market. It may be suggested

to those who wish to make phosphor bronze, but do not want to handle

phosphorus itself, to make it by using the proper amounts of one of

these high phosphorus alloys. In using phosphorus it is only necessary

to use enough to thoroughly deoxidize the metal, say 0.3 per cent. More

than this will make the metal harder, but not any sounder.

Phosphor bronze is not a special kind of alloy, but any bronze can be

made into phosphor bronze; it is, in fact, simply a deoxidized bronze,

produced under treatment with phosphorus compounds.

Although the effect of phosphorus in improving the quality of bronze

has been known for more than fifty years, it is only of late that

the mode for preparing phosphor bronze has been perfected. It is now

manufactured in many localities. Besides its action in reducing the

oxides dissolved in the alloy, the phosphorus exerts another very

material influence upon the properties of the bronze. The ordinary

bronzes consist of mixtures in which the copper is really the only

crystallized constituent, since the tin crystallizes with great

difficulty. As a consequence of this dissimilarity in the nature of

the two metals, the alloy is not so solid as it would be if both were

crystallized. The phosphorus causes the tin to crystallize, and the

result is a more homogeneous mixture of the two metals.

If enough phosphorus is added, so that its presence can be detected

in the finished bronze, the latter may be considered an alloy of

crystallized phosphor tin with copper. If the content of phosphor

is still more increased, a part of the copper combines with the

phosphorus, and the bronze then contains, besides copper and tin,

compounds of crystallized copper phosphide with phosphide of tin.

The strength and tenacity of the bronze are not lessened by a larger

amount of phosphorus, and its hardness is considerably increased. Most

phosphor bronzes are equal in this respect to the best steel, and some

even surpass it in general properties.

The phosphorus is added to the bronze in the form of copper phosphide

or phosphide of tin, the two being sometimes used together. They must

be specially prepared for this purpose, and the best methods will be

here given. Copper phosphide is prepared by heating a mixture of 4

parts of superphosphate of lime, 2 parts of granulated copper, and

1 part of finely pulverized coal in a crucible at a temperature not

too high. The melted copper phosphide, containing 14 per cent of

phosphorus, separates on the bottom of the crucible.

Tin phosphide is prepared as follows: Place a bar of zinc in an aqueous

solution of tin chloride. The tin will be separated in the form of a

sponge-like mass. Collect it, and put it into a crucible, upon the

bottom of which sticks of phosphorus have been placed. Press the tin

tightly into the crucible, and expose to a gentle heat. Continue the

heating until flames of burning phosphorus are no longer observed

on the crucible. The pure tin phosphide, in the form of a coarsely

crystalline mass, tin-white in color, will be found on the bottom of

the crucible.

To prepare the phosphor bronze, the {61} alloy to be treated is melted

in the usual way, and small pieces of the copper phosphide and tin

phosphide are added.

Phosphor bronze, properly prepared, has nearly the same melting point

as that of ordinary bronze. In cooling, however, it has the peculiarity

of passing directly from the liquid to the solid state, without first

becoming thickly fluid. In a melted state it retains a perfectly bright

surface, while ordinary bronze in this condition is always covered with

a thin film of oxide.

If phosphor bronze is kept for a long time at the melting point, there

is not any loss of tin, but the amount of phosphorus is slightly

diminished.

The most valuable properties of phosphor bronze are its extraordinary

tenacity and strength. It can be rolled, hammered, and stretched cold,

and its strength is nearly double that of the best ordinary bronze.

It is principally used in cases where great strength and power of

resistance to outward influences are required, as, for instance, in

objects which are to be exposed to the action of sea water.

Phosphor bronze containing about 4 per cent of tin is excellently

well adapted for sheet bronze. With not more than 5 per cent of tin,

it can be used, forged, for firearms. Seven to 10 per cent of tin

gives the greatest hardness, and such bronze is especially suited to

the manufacture of axle bearings, cylinders for steam fire engines,

cogwheels, and, in general, for parts of machines where great strength

and hardness are required. Phosphor bronze, if exposed to the air,

soon becomes covered with a beautiful, closely adhering patina, and is

therefore well adapted to purposes of art. The amount of phosphorus

added varies from 0.25 to 2.5 per cent, according to the purpose of

the bronze. The composition of a number of kinds of phosphor bronze is

given below:

─────+──────+─────+─────+─────+────+───────

│Copper│ Tin │ Zinc│ Lead│Iron│Phosp-

│ │ │ │ │ │horus

─────+──────+─────+─────+─────+────+───────

I.│ 85.55│ 9.85│ 3.77│ 0.62│trs.│ 0.05

II.│ — │ 4–15│ — │ 4–15│ — │ 0.5–3

III.│ — │ 4–15│ 8–20│ 4–15│ — │ .25–2

IV.│ 77.85│11.00│ 7.65│ — │ — │ —

V.│ 72.50│ 8.00│17.00│ — │ — │ —

VI.│ 73.50│ 6.00│19.00│ — │ — │ —

VII.│ 74.50│11.00│11.00│ — │ — │ —

VIII.│ 83.50│ 8.00│ 3.00│ — │ — │ —

IX.│ 90.34│ 8.90│ — │ — │ — │ 0.76

X.│ 90.86│ 8.56│ — │ — │ — │ 0.196

XI.│ 94.71│ 4.39│ — │ — │ — │ 0.053

─────+──────+─────+─────+─────+────+───────

I for axle bearings, II and III for harder and softer axle bearings, IV

to VIII for railroad purposes, IV especially for valves of locomotives,

V and VI axle bearings for wagons, VII for connecting rods, VIII for

piston rods in hydraulic presses.

«Steel Bronze».—Copper, 60; ferromanganese (containing 70 to 80 per

cent manganese), 40; zinc, 15.

«Silicon Bronze.»—Silicon, similarly to phosphorus, acts as a

deoxidizing agent, and the bronzes produced under its influence are

very ductile and elastic, do not rust, and are very strong. On account

of these qualities silicon bronze is much used for telegraph and

telephone wires. The process of manufacture is similar to that of

phosphor bronze; the silicon is used in the form of copper silicide.

Some good silicon bronzes are as follows:

I II

Copper 97.12 97.37

Tin 1.14 1.32

Zinc 1.10 1.27

Silicon 0.05 0.07

«Sun Bronze.»—The alloy called sun bronze contains 10 parts of

aluminum, 30 to 50 parts of copper, and 40 to 60 parts of cobalt. The

mixture known by the name of metalline has 25 per cent of aluminum, 30

of copper, 10 of iron, and 35 of cobalt. These alloys melt at a point

approaching the melting point of copper, are tenacious, ductile, and

very hard.

«Tobin Bronze.»—This alloy is nearly similar in composition and

properties to Delta metal.

I II III IV

Copper 61.203 59.00 61.20 82.67

Zinc 27.440 38.40 37.14 3.23

Tin 0.906 2.16 0.90 12.40

Iron 0.180 0.11 0.18 0.10

Lead 0.359 0.31 0.35 2.14

Silver — — — 0.07

Phosphorus — — — 0.005

The alloy marked IV is sometimes called deoxidized bronze.

Violet-colored bronze is 50 parts copper and 50 parts antimony.

«CADMIUM ALLOYS:»