US2259108A - Bearing alloy - Google Patents

Description

Patented Oct. 14, 1941 UNITED STATES PATENT OFFICE BEARING ALLOY Richards H. Harrington, Schenectady, N. Y., assignor to General Electric Company, a, corporation of New York No Drawing. Application July 11, 1939, Serial No. 283,829

Claims.

The present invention relates to bearing alloys and more particularly to a bearing alloy which is not only wear-resistant but has a high degree of heat conductivity. Prior to the present invention bearing alloys have been employed such shaft. The surface lead in the bearing waswiped out of the pockets in the alloy and these empty pockets, when the hearing was oiled, aided the lubrication. Such prior art bearings were defective since they did not have high heat conductivity. More recently copper-lead bearings have been available. While copper ofiers a soft matrix, it is too soft for many applications. This difference however is somewhat offset by the higher heat conductivity of the copper. The lead serves the same purpose as previously and comprises about 5 to 40% of the alloy with the balance copper. The copper-lead bearing alloys have no additional element included in the alloy to provide the hard particles which are desirable to absorb wear in the bearing. Other disadvantages ef the copper-lead alloy bearings are:

' (1) copper and-lead in the molten state form two liquid phases with the high lead phase settling to the bottom of the melt and (2) uneven and poor distribution of the lead after the alloy has solidified.

In carrying out my invention, I employ either of two matrix alloys, one consisting of copper, chromium, beryllium, in which the beryllium is not more than 1% of the alloy and the chromium-beryllium content not greater than 6% of the content of the alloy. The othermatrix alloy consists of copper, cobalt, beryllium with the beryllium again constituting not more than 1% of the alloy and the cobalt-beryllium constituting nor more than 7% of the alloy. The pre-: ferred compositions of the matrix alloys are:

In fabricating my improved bearing alloy, I employ in on case 50 to 1% lead with 50 1:099%

of the matrix alloy containing for example, .1% beryllium, .4% chromium, and 99.5% copper, or,

if desired, I employ 50 to 1% lead with 50 to 99% of the matrix alloy containing .4% beryllium, 2.6% cobalt, and 97% copper.

Preferred compositions of the two classes of bearing alloys are asfollows:

(a) 1. 95% (0.1Be-0.4Cr-99.5Cu) 5% Pb 90%(0.1Be-0.4Cr-99.5Cu) +10% Pb 80% (0.1Be-0.4Cr99.5C11) Pb 70% (0.1Be-0.4Cr-99.5Cu) +30% Pb 95% (0.4Be-2.6C0-97Cu) 5% Pb 90% (0.4Be-2.6C0-9'7Cu) +10% Pb 80% (0.4Be-2.6Co-97Cu) +20% Pb 70% (0.4Be-2.6C0-97Cu) +30% Pb In'fabricating the alloy the required quantity of copper is melted. The cobalt or chromium conquantity of beryllium plus about 0.1% beryllium ened has a heat conductivity of 45% or more and tent of the alloy is added to the melt either as metals or in the form of a copper base binary alloy. After about fifteen minutes the desired to a as a deoxidizer is added in the form of a copper-beryllium master alloy. After about ten minutes heating in the range of 1200 to 1300 C. the required amount of lead is added. The melt is kept covered with charcoal and after about ten minutes following the lead addition the alloy is poured into any suitable mold. For maximum physical, heat conducting, and electrical properties the alloy may be heat treated for about one-half to one hour from about 750 to 900 C., quenched from that temperature in water and then reheated two to five hours at about 500 C. and thereafter cooled in air. Desirable bearing properties however may be obtained by eliminating the solution treatment and simply ageing the bearings for about one to four hours at 500 C. and cooling in air or in furnace. This is particularly true of rapidly cooled or chilled castings. The matrix of the bearing alloy containing .1% beryllium, .4% chromium and 99.5% copper when precipitation hardened has a heat conductivity of or more and a proportional limit of 18,000 pounds per square inch while the matrix of the alloy containing .4% beryllium, 2.6% cobalt and 97% copper when precipitation harda proportional limit of 45,000-pounds per square inch. Thes results may be compared with the.

% of that of cold worked and annealed copper (100%) and aproportional limit of about 3000 pounds per square inch. Since the lead employed in my improved bearing alloys occurs in a free state with practically so solubility in the copperberyllium alloy matrix in the solid state, the ma-.

trix may be heat treated as hereinbeforepointed out to produce the above physical properties. Since the presence of free lead distributed in pockets throughout the ternary copper alloy matrix diminishes the properties of the lead-free .alloys in proportion to the amount of lead pres- 70% (0.4Be-2.6Co-97Cu) +30% Pb as cast had a Rockwell B hardness of 35. The same alloy when aged 1% hours at 500? C. had a Rockwell B hardness of 54. Itis possible with the two difierent matrix compositions and by varying the lead content to develop wide ranges of heat conductivities with various load limits to meet requirements ranging from light loads and high speeds to heavy loads and slow speeds as well as high speeds.

In my improved bearing alloys the free lead is uniformly distributed in the solid state due to two factors.

(1) In the presence of a strong deoxidizer, beryllium, the melt is apparently constituted of a single liquid phase, and (2) These compositions are very sluggish in the molten state for about 100 0. above the melting point, which opposes gravity separation of the lead to the bottom of the melt before and during solidification.

That the lead is well distributed in the solid state may be shown for example in a cast rod 1%" in diameter by 12" long. Such a rod as cast will have uniform hardness values in transverse and longitudinal sections. These results may be checked by microscopic inspection. When my improved alloyscontaining up to 30% lead are heated even as high as 900 C. only the lead which is exposed on the surface of the piece sweats out, the interior remaining unaffected.

My improved alloy bearing combines all the advantages of standard bearing alloys with the additional advantage of very high heat conductivity. The alloy also has the advantage that it contains a tough matrix of solid solution which may be strengthened by ageing at 500 C. It contains hard particles of chromium-beryllium or cobalt-beryllium for wear resistant purposes and it contains varying amounts of lead for plasticity and as an aid in lubrication. Various changes in the properties of the material may be obtained by varying the temperature of pouring the casting, the rate of cooling, the choice of matrix composition, the amount of added lead, and the heat treatment.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. A bearing member containing copper, lead, beryllium and metal from the group cobalt and chromium, the lead comprising about 5% to 30% of said member, the remainder of said member consisting of a matrix alloy said matrix alloy containing up to about 1% of beryllium, and up to about 6% of metal from said group with the remainder copper.

2. A bearing member having the following composition: 5 to 30% lead and 95 to of a matrix alloy, said matrix alloy containing about 0.1% beryllium, 0.4% chromium and 99.5% copper.

3. A hearing member having the following composition: 5 to 30% lead and to 70% of a matrix alloy containing about 0.4% beryllium. 2.6% cobalt, and 97% copper.

4. A bearing member having the following composition: 5 to 30% lead and 95 to 70% of a precipitation hardened matrix alloy, said matrix alloy containing about 0.1% beryllium, 0.4% chromium and 99.5% copper.

'5. A bearing member having the following composition: 5 to 30% lead and 95 to 70% of a precipitation hardened matrix, said matrix containing about 0.4% beryllium, 2.6% cobalt and 97% copper.

RICHARDS H. HARRINGTON.