US2156802A - Method of making lead alloys - Google Patents

Description

May 2, 1939. H. s. COOPER METHOD QF MAKING LEAD ALLOYS Filed March '7, 1934 a N? M aw m 0Q Patented May 2, 1939 UNITED STATES PATENT OFFIC METHOD OF MAKING LEAD ALLOYS Hugh S. Cooper, Shaker Heights, Ohio, assignor to Cooper Products, Inc., Cleveland, Ohio, a corporation of Ohio The present invention relates to metal alloys or conglomerates comprising lead and a method of making the same. More particularly the invention relates to alloys or conglomerates of lead and certain metals, compounds, especially the oxides, of which are reducible preferably by hydrogen at temperatures below or not greatly in excess of the vaporization temperature of lead, such as copper, silver, iron, nickel, cobalt, tungsten, and molybdenum.

If an attempt is made to prepare alloys or conglomerates of lead and one or more metals, such as those noted above, by the common method of melting and casting, the lead rapidly separates itself from the other or others during the cooling process, owing to the immiscibility of the metals in the liquid state. In the resulting product the lead is either unevenly distributed or may possibly be segregated completely from the other metal or metals. Various attempts have been made to prevent the separation of the lead from the other metals, such as the addition of sulphur, tin, etc., without success. According to the present invention, alloys or conglomerates comprising lead are produced which have a uniform or other predetermined distribution of the lead throughout the product as the metals combined never reach a melted or molten state, and consequently there can be no separation of the lead. The alloys and/or conglomerates of the present invention have special utility as bearing metals.

An object of the present invention is the provision of a novel alloy or conglomerate compris- 35 ing lead in which there will be a predetermined distribution of the lead throughout the same.

Another object of the invention is the provision of a novel alloy and/or conglomerate comprising lead and a metal the oxide of which is 0 reducible by hydrogen at temperatures less than or not greatly in excess of the vaporization temperature of lead.

Another object of the invention is the provision of a novel alloy and/or conglomerate com- 45 prising lead and copper, silver, iron, nickel, co-

balt, tungsten, and/or molybdenum in which the lead will be uniformly distributed through the product.

Another object of the invention is the provision of a novel bearing metal containing lead in which the lead has a predetermined or a uniform distribution throughout the product.

Another object of the invention is the provision of a novel bearing, bushing, etc. containing 55 lead in which the distribution of the lead throughout the article is either uniform or predetermined.

Another object of the invention is the provision of a novel method of making an alloy and /or conglomerate of lead which comprises preparing a predetermined mixture of compounds of the metals to be alloyed, reducing the compounds, subsequently compressing the resulting product, and sintering at a temperature less than or not greatly exceeding the vaporization temperature of the metals. I

Another object of the invention is the provision of a novel method of making an alloy and/or conglomerate containing lead which comprises preparing a uniform mixture of the oxides of the metals tobe combined, reducing the mixture by hydrogen at a'temperature less than the vaporization temperature of lead which will produce a fine powder, subsequently compressing the resulting powder, and sintering at a temperature at which the lead will not sweat out of the mass.

Further objects and advantages of the present invention will be apparent to those skilled in the art to which it pertains from the following description of the preferred embodiments of the alloys and /or conglomerates and preferred methods of making the same, described with reference to the accompanying drawing, in which:

Fig. 1 is a perspective view, with a portion in section, of a valve guide embodying the present invention;

Fig. 2 is a perspective view, with a portion in se tion, of a bushing embodying the present invention;

Fig. 3 is a perspective view of a rolled sheet of material embodying the present invention; and

Fig. 4 is a perspective view of a bearing cap lined with bearing metal of the present invention.

According to the present invention, alloys con-' taining lead, having a uniform distribution of the lead through the finished product, are produced by a method which contemplates the reduction, preferably by hydrogen, of a mixture of powdered compounds, preferably oxides, of the ,metals to be combined at a temperature less than the vaporization temperature of lead which will produce a uniform, fine powder, after which the resulting powder or mass is pressed to any desired form and sintered at a temperature less than the vaporization temperature of lead at which the lead will not sweat out of the mass. The sintered product may be finished as desired in any suitable manner, such as by machining,

etc., or it may be rolled into sheets, etc. During the process the metals never reach a molten state, and, consequently, there can be no separation of the lead and a uniform distribution of the lead throughout the product is obtained.

For the purpose of more clearly illustrating the invention, lead-copper, lead-tungsten, and lead-iron alloys or conglomerates will be specifically described, together with the method of making the same, as the preferred embodiments of the invention, but it will be understood that the invention is not limited to these specific alloys.

In the preparation of a metal compound containing approximately 50% each of lead and copper, a mixture of powdered lead oxide and powdered copper oxide in the proportion of 223 parts of the lead-compound to 237 parts of the copper compound by weight, as a specific example say 223 grams of lead oxide (PhD) and 237 grams of copper oxide (CuO), is thoroughly mixed for several hours in a porcelain mill to obtain a uniform composition. The loose powder is then placed in boats, which may be either iron or nickel, etc., and heated in hydrogen at approximately 500 C. for about two hours, or until the oxides are completely reduced and a uniform fine powder is produced. The powder has an appearance of interwoven crystals, isof a bronze color, and is very fine and uniform in composition. The resulting powder is pressed to the desired shape between steel dies at pressures ranging from about 10,000 to 25,000 pounds per square inch, and subsequently sintered in hydrogen at temperatures around 500 C. The alloy or conglomerate thus obtained makes a very suitable bearing metal and contains a uniform distribution of the lead throughout the copper. When it is desired to make bearings or bushings such as illustrated in Fig. 2 of the drawing, the reduced powder is preferably pressed to an appropriate shape before the sintering step, and after sintering, is machined to size, etc. If it is desired to roll the material into sheets, the reduced powder is merely pressed into a rectangular slug and sintered, after which the slug may be rolled to any desired shape and thickness. If desired, other metals may be added, such as iron in the form of iron oxide, and it is to be understood that the proportions of the various metals may be varied as desired within Wide limits so long as lead is present in substantial amounts.

A lead-tungsten alloy or conglomerate containing approximately 50% each of lead and tungsten maybe prepared in a similar manner. A mixture of powdered lead oxide and powdered tungsten oxide in the proportion of 223 parts of the lead compound to 232 parts of the tungsten compound, by weight, for example 223 grams of lead oxide (PhD) and 232 grams of tungsten oxide (W03) when thoroughly mixed, as outlined above, and reduced by hydrogen at temperatures ranging from 700 C. to 950 0., yields a very uniform, fine gray powder which, when compressed and. sintered at approximately 700 C. gives an alloy of high ductility showing a hardness of from 30 to 40 on the Brinell scale, and one which has a uniform distribution of lead throughout the resultant product. Sections of this alloy which are not too thick are so malleable that they can be rolled to thin sheets as was the case with the lead-copper alloy referred to above. The proportions of lead and tungsten may be varied as desired, and other metals may be added thereto, such as molybdenum. Compounds other than arcades the oxides of the metals may also be used, such as ammonium tungstate in place of the tungsten oxides.

Lead-iron alloys or conglomerates oi approximately 50% each of lead and iron having a uniform distribution of the lead throughout the product may be produced by thoroughly mixing powdered lead oxide with powdered iron oxide in the proportions of approximately 223 parts of the lead compound to 300 parts of the iron compound by weight. As a specific example, 223 grams of powdered lead oxide (PbO) are thoroughly mixed with 300 grams of iron oxide (F8203) until a uniform powder is produced. This powder, when reduced by heating in hydrogen at approximately 700 C. for about one hour, produces a very uniform, fine, dark gray or black powder which is compressed and sintered at approximately 500 C. The sintered product is quite malleable and shows a Brinell hardness of about 60 to 70. This product differs from the other alloys noted above in that it can be heated to 600 C. without evidence of lead-sweating and with but very little change in hardness. The proportions of lead oxide and iron oxide may be varied as desired, thereby obtaining alloys of any desired composition, and other metals, such as nickel, may be added thereto in a similar manner.

Due, to the high lubricating value of lead, the

compounds of the present invention, especially those containing a substantial proportion of lead,

are especially suited for making bearings, bushings, valve guides, etc. Whether or not the metal compounds of the present invention are true alloys or conglomerates of a combination of each is indetermined and probably depends upon the particular combination of metals employed in any specific product, and is considered immaterial for the purposes of the present invention.

Referring to the drawing, Fig. 1 illustrates a valve guide designated in general by the reference character l0 and embodying the present invention. The particular valve guide illustrated comprises a tubular body portion provided with a flange I I at the upper end thereof and is made of the lead-tungsten metal composition previously described by pressing the fine powder resulting from the reducing step of the process into approximately the desired shape, and, after sintering, machining to size.

Fig. 2 of the drawing illustrates a bushing l2 made of the lead-copper composition described by pressing the lead oxide copper oxide powder, after being reduced, into the shape illustrated and sintering.

Fig. 3 illustrates a sheet l3 of the lead-iron composition which has been rolled to the shape shown from a cubical sintered slug.

A bearing cap M comprising a conventional steel or iron back i5 lined with a lead-copper composition l6 made in accordance with the present invention is shown in Fig. 4. The particular lining illustrated is 50% each of lead and copper with a uniform distribution of the lead throughout the copper and has been cut from a rolled sheet of the material.

From the foregoing disclosure of the invention it will be apparent that new metal compounds, bearing metals, bearings, and bushings have been produced, i. e., compounds, bearing metals, bearings, and bushings comprising lead having a uniform or other predetermined distribution of the lead throughout the product. It will also be apparent from the foregoing that new and improved methods of producing metal compounds awopoa and articles containing lead have been produced.

It is not intended to be limited to the specific metals, compounds, articles, and methods mentioned, as it will be apparent from the foregoing that metals other than those mentioned may be employed, that compounds of the metals other than the oxides may be used, that the initial metal powder may be reduced by agents other than hydrogen, that various proportions and distributions of the metals may be used and obtained, and that the products of the invention have innumerable uses. When the products are to be used for hearing purposes, the lead is preferably present in quantities ranging from to 80% of the whole.

While I have described the preferred embodiments of my invention, it is my intention to cover any and all variations, adaptations or uses thereof as come within the knowledge and customary practice in the art to which it appertains, and I specifically point out and claim as my invention the following:

i. The method or mahng a sintered metallic composition consisting of lead and other metal in which the lead is tmiformly distributed which comprises reducing by hydrogen at a temperature less than the'va'porization point of lead a uniform mixture consisting of lead oxide and the oxide of a metal reducible by hydrogen at a per, which comprises reducing a uniform mixture ofapproximately to lead oxide and the balance substantially copper oxide by a gaseous substance at approximately 500 6., compressing the reduced composition to a desired shape, and subsequently sintering the compressed composition at approximately 500 C.

HUGH B. COOPER.

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