US 2752241 A
Description (OCR text may contain errors)
June 26, 1956 w, v, BERRY 2,752,241
COPPER BASE NICKEL,ANTIMONY, LEAD BEARING ALLOY Filed July 9, 1952 APPlICANT'S ALLOY 80% COPPER, 10% TIN, 10% [MD AllOY IN VEN TOR.
Wa/fis/ ll Ber/ B CQPPER BASE NECKEL, ANTHMQNY, LEAD EEARENG ALLQY Walter V. Berry, Pittsburgh, Pa., assignor t Eerry l ietal Company, Reno, New, a corporation or Nevada My invention relates to the providing of an improved copper base bearing alloy.
More particularly, my invention relates to a bearmg alloy characterized by the absence of tin as one of the alloying metals and at the same time characterized by its great load carrying capacity by having properties which substantially match or improve the recognized desired properties of the copper base tin bronze bearing alloys, said matching involving such properties as the microstructure, hardness, yield strength, compressive strength, low frictional resistance and long life.
This is critically important to the United States due to the fact that a great proportion of our supply of tin comes from Asia and since such sources of supply are subject to being cut off by war, it is highly essential that the United States be rendered independent of such sources of tin for hearing purposes.
it is readily comprehensible that conservation of tin in bronze bearing metals makes more tin available for munitions, ordnance, Army and Navy equipment and tin plate, represented by tin cans and containers which are a prime necessity for feeding and supplying of troops and civilian population.
in providing a copper base bearing alloy which contains no tin, an almost priceless asset is being conserved which may involve the very survival of our Nation as a free country.
By experiment and long usage, it has long been proved that an alloy containing 80% copper, tin and 10% lead is one of the best alloys known for bearing purposes, especially where hard usage and heavy loads are to be carried, such as in the service of railroads and steel rolling mills.
A primary object of my invention is to provide without the employment of tin, the welbknown alpha-delta type of microstructure of said 80% copper, 10% tin, 10% lead alloy which is well known as a bearing metal structure. The alpha constituent of said microstructure consists of a reasonably soft and yielding ground-mass, or matrix, in which is embodied a network of hard material, or compounds, known as the delta constituent. This network of hard material, i. e., the delta constituent, supports the load and imparts good wearing qualities to the alloy. At this point be it noted that pure metals such as copper, nickel, tin, lead, iron and aluminum alone make poor bearing materials and bearings made of them usually fail to pass the first test of possessing resistance to seizure. Furthermore, and above all, such pure metals alone are characterized by very poor wearing qualities. Accordingly, the critical importance of the presence of a network of hard material, or compounds, in a bearing metal, together with a uniform and proper distribution of this network of hard material, is manifest.
A further primary object of my invention is to provide a copper base bearing alloy without the use of tin which is strongly characterized by having an alpha-delta type of microstructure in which the embodied network of hard material, or compounds, which supports the load atent Patented June 25, 1%555 2 and imparts good wearing qualities to the alloy, is particularly uniformly distributed.
A further object of my invention is to provide a copper base bearing alloy, without the use of tin, which is characterized by its contribution to re istance to wear, corrosion, heat, fatigue, and impact without adversely aifectthe microconstituents or pattern of microscopic inhomogeneity of the alloy.
A further object of my invention is to provide a copper base bearing alloy, without the use of tin, which matches in a high degree the metallurgical properties of said copper, 10% tin, 10% lead alloy. Investigation has shown that said properties are related to good bearing qualities, such as microstructure, hardness, yield strength, compressive strength, low frictional resistance and long life.
A further object of my invention, and one which is highly important, is to provide an alloy, without the use of tin, in which a high lead content may be used and in which such lead content will not segregate when originally cast or when re-melted and re-cast.
A further object of my invention is to produce a bearing alloy, without the use of tin, in which the lead is finely dispersed and uniformly suspended in the matrix. The alloy of my invention is generally free from segregation, including stringiness and other imperfections usually found in the copper-lead, or the copper-tin-lead, or the copper-tin-lead-zinc bearing metal alloys.
The lead in my alloy functions to lower the coefiicient of friction, increases resistance to wear, and operates in a manner akin to that of a lubricant. The distribution of lead is found to be superior to that of the 80% copper, 10% tin, 10% lead bearing alloy. This distribution involves the lead in an effective functional character (including that of facilitating lubrication) adjacent to the hard inter-metallic compounds of the delta constituent.
A further object of my invention is to produce a copper base bearing alloy which is more economical to manufacture than such alloys containing tin by reason of my discovery that certain low priced components may be effectively and practically substituted for said tin without sacrificing the desired properties of the best copper base tin alloys.
A further object of my invention is to produce an alloy which will have application as a bearing metal and is characterized by having components which are readily united in such proportions as may be most suitable for each particular application or use. It is well recognized that bearing metals require certain properties which must be variable for particular uses. These properties must vary as to hardness, yield strength, tensile strength, cornpressive strength, and fatigue resistance.
In the drawings, like reference numerals indicate like phases or portions of the microstructure of the alloy of my invention. In parallel columns for clearness of comparison are shown phases or portions of the 80% copper, 10% tin and 10% lead bearing alloy of common practice composition.
Figure 1 is a photomicrograph of an alloy of my invention embodying my preferred formula under magnification. showing the alpha-delta type of structure etched with a solution containing ferric chloride and hydrochloric acid;
Fig. 2 is a photomicrograph of the same alloy of Fig. 1 but under 250 magnification;
Fig. 3 is a photomicrograph of an alloy of 80% copper, 10% tin and 10% lead under 100 magnification and etched as in the case of Fig. 1;
Fig. 4 is a photomicrograph of the alloy shown in Fig. 3 under 250 magnification;
Fig. 5 is an unetched photomicrograph of the alloy of my invention, illustrated in Figs. 1 and 2, showing the well dispersed and uniform distribution of the lead phase under 50 magnification; and
Fig. 6 is an unetched photomicrograph of the 80% copper, 10% tin and 10% lead alloy illustrated in Figs. 3 and 4, showing the lead phase under 50 magnification. In the alloy of my invention, characterized by having the alpha-delta type of microstructure, there is a gradual graduation of portions of low antimony content to portions of high antimony content. The latter portions supply the hard compounds in the bearing alloy. This gradation of antimony content is clearly revealed in the difference in color as follows:
First, the jet black phase 10 is for the most part lead. Second, the dark gray phase 11 is the alpha constituent, or matrix, low in antimony. Third, the small islands 12, light in color, often appearing of annular form, is a phase of relatively high antimony content. Fourth, the small light colored circular nucleus 13 is the phase of still higher antimony content providing the extremely hard portion of the bearing alloy. Thus, there is this gradual gradation of increasing antimony content. The phases 12 and 13 are the hard materials or compounds herein referred to as the delta constituent. Particularly, be it noted that the very high antimony phase 13 is surrounded by the relative hard phase 12 which functions as an intermediary portion between the phase 13 and the matrix 11.
In Fig. 2, the microstructure of Fig. 1 is magnified 250 times and showns clearly and in detail the matters set forth above. Attention is particularly called to the excellent distribution of the hard and soft phases which has been achieved in applicants alloy. Such a result has apparently not been successfully obtained by others in the past, so far as applicant has been able to discover.
In Figs. 3 and 4, the photomicrographs show the alpha-delta microstructure of an 80% copper, 10% tin and 10% lead alloy, Fig. 3 showing magnification of 100 while in Fig. 4 the magnification is 250.
The lead phase 14 corresponds to the jet black lead phase 10 of applicants alloy shown in Fig. 1.
The dark gray phase 15, that is, the alpha constituent, or matrix, is the phase low in tin. Next, we come to a distinct difference between applicants alloy and that of the 80% copper, 10% tin and 10% lead alloy. In Figs. 3 and 4, there is no corresponding phase, it seems, of the light colored phase 12 as appears in Figs. 1 and 2 of the microstructure of applicants alloy. We next find the light colored phase 16 which represents the phase high in tin content. These are the hard materials or compounds which are known as the delta phase of the alpha-delta eutectic. It will be noted that the phases 13, representing that portion of the applicants alloy which is high in antimony content, are far more evenly distributed than are the phases 16 representing the portions high in tin content of the 80% copper, 10% tin and 10% lead alloy of present day commercial practice.
To illustrate a further differentiation between applicants alloy and that of the 80% copper, 10% tin and 10% lead, the unetched photomicrographs, Figs. and 6, are included to show the greater uniformity and greater dispersion of the lead content in the alloy of applicant.
My invention or discovery summarily, briefly and therefore incompletely stated is as follows: It comprises a copper base to which appropriate percentages of nickel, antimony and lead, with phosphorus, are added, said percentages depending upon the service requirements. Variations in said percentages are necessary in order to obtain any one or a combination of the properties above set forth. Specifically, the alloy may contain from 55% to 85% copper; /2% to nickel; 3% to antimony; 1% to 35% lead, and from a trace (0.001%) to 3% phosphorus. A preferred formula of my invention or discovery of a copper base alloy containing nickel, antimony, and lead, with phosphorus, which is suitable for general application as a bearing metal, is as follows: Copper 82.35%; nickel 1.50%; antimony 6.00%; lead 10.00%; and phosphorus 0.15%.
Test bars cast from the above preferred alloy exhibited the following physical properties which are compared with the physical properties, given in paralleling columns, required by the American Society for Testing Materials covering copper base bearing alloys containing tin:
A study of the microstructure of the applicants alloy, without tin, including the preferred formula, shows a microstructure similar in type to the alpha-delta structure observed in the copper, 10% tin, 10% lead alloy but of a marked improved character as to the delta constituent in the microstructure, particularly respecting uniformity and distribution of said delta constituent. The alpha constituent is the alloy of applicant, comprising essentially copper, nickel, and antimony, is the ground-mass or matrix. The delta constituent, comprising essentially copper, nickel and higher percentages of antimony than in the alpha constituent, together with any copper and/ or nickel phosphides which may be present, provides a network of hard inter-metallic compounds which support the load and impart good wearing qualities to the alloy.
The composition of a prior admixture of antimony and phosphorus with copper and lead, but without nickel, and not characterized by the copper-nickel-antirnony hard phases herein referred to, is given in the following table, in order that the physical properties of this alloy may be readily compared with and differentiated from the physical properties of applicants alloy:
Compres- Brinell Cu, Pb, Ni, Sb, P, sion Tensile Yield Hard- Per- Per- Per- Per- Per- Strength, Strength, Strength, ness, cent cent cent cent cent 0.100 set, p.s.i. p.s.i. 500 kg.
p.s.i. Load APPLIOANT'S PREFERRED FORMULA A critical marked improvement in the physical properties is thus shown to be provided by applicant's invention or discovery over said prior admixture.
At this point be it remembered that in the economical copper base alloys, the microstructure, or pattern, known as the alpha-delta structure characterizes bearing metals containing a high percentage of tin. Moreover, in fact, such structure heretofore has only been known in connection with copper base alloys containing a relatively high percentage of tin. Therefore, applicant has made the important discovery that he can provide a greatly improved alpha-delta type of microstructure without the use of tin in a copper base bearing alloy.
My invention involves the discovery that proper proportions of nickel, antimony, and lead, with phosphorus, within the limits herein described, can be combined with copper to form a bearing alloy which contains no tin but which contains compounds containing antimony, herein referred to as the delta constituent, which are characterized by their hardness. This alloy has all the desirable metallurgical properties of the well known 80% copper, tin and 10% lead alloy, and has considerably better physical properties and microstructure than the copperantimony-lead-phosphorus alloys heretofore known.
Applicant does not use phosphorus in his discovery primarily as a hardening agent since he has discovered that increasing percentages of phosphorus, up to 1%, adversely affects the hardness of the alloy. Phosphorus is used by applicant primarily for the following reasons: For its effect in assisting in the formation and distribution of the delta or hard constituent in the alloy; to minimize shrinkage; and to combine with nickel and/or copper to form nickel and/or copper phosphides. Moreover, plicant does not use phosphorus primarily as a deoxidizing agent because a greater percentage of phosphorus is used than is normally required for deoxidizing benefits. Deoxidizing benefits are, however, imparted to the alloy while using phosphorus for the above reasons.
Nickel is used to reduce the solubility of antimony in the copper which brings about a precipitaton during solidification of compounds characterized by their hardness. These compounds are thought to contain copperantimony, or they may be copper-nickel-antimony, intermetallic compounds which, together with any phosphides of copper and nickel which may be present, form the delta constituent of the alloy herein described. The applicant employs the nickel to cause a separation of the antimony from the copper in a series of compounds which contain a higher percentage of antimony than is contained in the alpha constituent, and as a consequence are much harder than the alpha constituent. Lack of knowledge of this copper, nickel, antimony system makes positive labelling of the phases impossible. It can only be stated that the phase we designate as the delta constituent comprises the higher-antimony, hard phases in the alloy together with any phosphides which may be present. From the constitution diagram for the copper-antimony system published in the 1949 Metals Handbook, it can be inferred that the hard phases referred to are the gamma and delta phases and that they occur together because the gamma phase did not completely transform to produce the deita phase. Another possibility that must be considered is that a ternary phase is accompanying either the gamma phase or the delta phase. Such ternary phase would probably consist of copper, nickel and antimony.
Employed in this manner, i. e., causing said precipitation or separation of antimony from the copper, nickel also hardens the alloy and increases its compressive strength. It toughens the alloy by binding together the crystalline mass and thus assists in preventing disintegration of the alloy under abrasive action. The discovery of preventing disintegration under abrasive action is established as characterizing my invention by an experirnent with bearings in a steel rolling mill where particles of iron oxide, in the form of scale, were injected into the bearings from the ingots being rolled. The alloy of my invention withstood the strenuous abrasive action of said scale.
Advantages gained by substituing this invention for the copper base alloys containing tin are as follows:
Tin conservation in the interest of national security while at the same time providing an improvement in copper base alloys.
Metallurgy: The discovery that an alpha-delta type of Less gasiness and consequently less difiiculties in producing sound castings.
' Improved fluidity during the period involved in casting with corresponding less shrinkage; and
Freedom from structural irregularities and weaknesses.
Generally speaking, the above described invention or discovery can be employed in any application where a copper base bearing alloy containing tin may normally be used. Some suggested uses are street car, mine and railroad car journal bearings, cross-head bearings, armature and electrical motor bearings, machinery bearings, internal combustion engine bearings, rod bushings, shoes, wedges, machine tool bearings, pump bearings, pump impellers and general bushing stock.
In producing the alloy the copper is first melted in a suitable melting furnace and under an oxidizing atmosphere to prevent the absorption of gases. Nickel is introduced by way of copper-nickel alloys in shot or ingot form, or by way of products containing coppernickel, such as Monel metal, in which case the per cent of copper in the copper-nickel alloy must be taken into consideration. When the copper, and copper-nickel alloy is liquid, the antimony is added, then the lead, in the same manner in which alloying metals are usually added to obtain a thorough mixing. The phosphorus is introduced by the use of phosphor-copper which normally contains 10% to 15% phosphorus, in which case the per cent of copper in the phosphor-copper must be taken into consideration. The phosphor-copper is introduced last and usually about five minutes prior to pouring. The molten charge is then poured into ingots, sand, or metal molds; or it can be atomized for use in powder metallurgy. In producing the alloy, melting losses and allowances or additions for melting losses must be taken into consideration and will vary depending upon the size and shape of the material melted and the type of melting furnace used.
Small amounts of other components, not to exceed 2%, may be added to mixes of the above described basic components taken as 100%, in order to improve particular properties of the present alloy, such as tellurium or cadmium, which are effective in improving the grain structure.
Heretofore, difiiculties have been experienced in trying to form a copper base alloy of required physical properties in which antimony is a component. One of such difticuities was that antimony caused the alloy to be too brittle. My invention has overcome this diiiiculty and provides an alloy with the advantages and greatly improved physical properties herein set forth, particularly where there is a great bearing load to be carried. It appears that the use of antimony in combination with the nickel in accordance with the invention herein set forth has primarily contributed to the overcoming of said difficulty.
Having thus described my invention, what I claim by Letters Patent is:
l. A copper base alloy consisting essentially of 55% to copper, /z% to 10% nickel, 3% to 15% antimony, 1% to 35% lead, and a trace (0.001%) to 3% phosphorus, said alloy containing inter-metallic compounds of nickel, copper, antimony and phosphorus, which compounds are characterized by their hardness.
2. A copper base alloy consisting of 55% to 85% copper, /2% to 10% nickel, 3% to 15% antimony, 1% to 35% lead, and a trace (0.001%) to 3% phosphorus, said alloy containing intermetallic compounds of nickel, copper, antimony and phosphorus, which compounds are characterized by their hardness.
3. A copper base alloy consisting essentially of 55% to 85% copper, /2% to 10% nickel, 3% to 15% antimony, 1% to 35% lead, and a trace (0.001%) to 3% phosphorus, said alloy containing inter-metallic compounds of nickel, copper, antimony and phosphorus, which compounds are characterized by their hardness, and having a compression strength of about 46,000 p. s. i. at a set of 7 0.100 inch, yield strength of about 23,000 p. s. i. and a tensile strength of about 30,000 p. s. i.
4; A copper base alloy consisting of 55 to 85% copper, /z% to 10% nickel, 3% to 15% antimony, 1% to 35% lead, and a trace (0.001%) to 3% phosphorus, said alloy containing inter-metallic compounds of nickel, copper, antimony and phosphorus, which compounds are characterized by their hardness, and having a compression strength of about 46,000 p. s. i. at a set of 0.100 inch, yield strength of about 23,000 p. s. i. and a tensile strength of about 30,000 p. s. i.
5. A copper base alloy consisting essentially of 55% to 85% copper, /2% to 10% nickel, 3% to 15% antimony, 1% to 35% lead, and a trace (0.001%) to 3% phosphorus, said alloy containing inter-metallic compounds of nickel, copper, antimony and phosphorus, which compounds, characterized by their hardness, show an alpha-delta type of microstructure in which the constituents are relatively uniformly distributed.
6. A copper base alloy consisting essentially of 55% to 85% copper, V2% to 10% nickel, 3% to 15% antimony, 1% to 35% lead, and a trace (0.001%) to 3% phosphorus, said alloy containing inter-metallic compounds of nickel, copper, antimony and phosphorus, which compounds, characterized by their hardness, show an alpha-delta type of microstructure with gradation from portions of low antimony content to portions of high antimony content.
7. A copper base alloy containing /2 to 10% nickel, 3% to 15% antimony, 1% to 35% lead, a trace (0.001%) to 3% of phosphorus, the balance of the alloy being substantially copper and said alloy being characterized in having a compressive strength 1" about 46,000 p. s. i. at a set of 0.100 inch, yield strength of about 23,000 p. s. i. and a tensile strength of about 30.000 p. s. i.
8. A copper base alloy comprising about 82.35% copper, about 10% lead, about 0.15% phosphorus, and the balance consisting essentially of about 6% antimony and about 1.5% nickel, said alloy containing inter-metallic compounds of nickel, copper, antimony and phosphorus which compounds are characterized by their hardness. 9. A new article of manufacture comprising a powdered copper base alloy in the form of a loose mass of particles, said alloy consisting essentially of 55% to 85% copper, /2% to 10% nickel, 3% to antimony, 1% to 35% lead and a trace (0.001%) to 3% phosphorus.
10. The method of making a copper base alloy consisting essentially of forming a molten mass, 55% to 85% copper, 1% to 35% lead, 3% to 15% antimony, and a trace (0.001%) to 3% of phosphorus, comprising adding as a solubility reducing agent /2% to 10% of nickel to said copper, lead, antimony and phosphorus combination, said agent functioning to reduce the solubility of antimony in the copper and cause a precipitation during solidification of the compounds containing antimony which com:
pounds are characterized by their hardness.
References Cited in the file of this patent UNITED STATES PATENTS 1,223,001 Sandell Apr. 17, 1917 1,286,921 Berry Dec. 10, 1918 1,975,216 Wecker Oct. 2, 1934 2,466,700 Grodsky Apr. 12, 1949 OTHER REFERENCES Sir Isaac