US1585786A - Aluminum alloy and method of manufacture - Google Patents

Description

Patented May 2 5, 1926.

UNITED STATES PATENT. OFFICE. I

HENRY KNEELAND RICHARDSON, OF NEWARK, NEW JERSEY, ASSIGNOR TO WESTING- HOUSE LAMP COMPANY, A CORPORATION QF PENNSYLVANIA.

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This invention relates to alloys of aluminum and more particularly to such alloys in which zirconium serves to neutralize the deleterious effect of certain impurities.

I An object of my invention is the produc-- tion of alloys of aluminum having high ductility, directly from impure aluminum ore.

' Another object of my invention is to simplify the manufacture of aluminum, by using zirconium alloyed therewith, whereby it is unnecessary to purify the bauxite or other aluminum ore to obtain a product of high ductility.

A further object of my invention is the employment of zirconium to alloy with aluminum to neutralize the harmful effect-of impurities such as iron, which render it brittle and nonductile, and form an alloy of greater strength than heretofore produced without using zirc mium.

' A still further object of my invention is the simultaneous electrolysis or reduction of impure bauxite and zirconium oxide to produce an alloy of aluminum, zirconium and other metal impurities, the harmful effect of the impurities being neutralized by the zirconium.

Other objects and advantages will become apparent as the description proceeds.

As is well known, aluminum is manufactured commercially by electrolysis of the fused ore and in order that the product may have ductility and not be too brittle, it is B necessary when using ore containing impurities such as iron, to carefully purify the-same;

According to the Heroult process, cryolite (Na AlF,) mixed with alumina (Al,() or 40 bauxite Al O 3H O) is fused in an electric furnace tween carbon electrodes. num fluoride, calcium fluoride, sodium'chloride or other compounds, are sometimes'added to reduce the melting point of the electrolyte and diminish the density, so as to facilitate theseparation of the'aluminum to the bottom of the fused bath. Any impuri ties in the aluminum ore, such as compounds of iron, will be reduced and alloy with the aluminum, resulting in a brittle and nonductile metal. I a

In using aluminum ore or bauxite containing such impurities, it has been necessary to submit the same to a careful and Alumi- Application filed November 5, 1928. Serial No; 672,717.

costly purification process in order to obtain aluminum having the desired properties.

'According to my invention, I obviate the necessity of the usualpurification process by adding to the fused electrolyte, a material which, upon reduction, furnishes a metal which neutralizes the effect of impurities such as iron.

My invention will be better understood by the more detailed description thereof which follows.

In general, one of the usual commercial processes, such' as the Hall or the Heroult process, may be employed for making alumities of compounds of iron and silicon, may

be dissolved in the fused electrolyte, in such proportions, that the melting point thereof is a minimum or not excessively high, although the exact proportions used are not material. The proportion of alumina to cryolite or its equivalent in the mixture is preferably about 20% to secure a minimum fusing temperature.

A small proportion of zirconium oxide or other zirconium compound may be mixed with the bauxite or alumina before dissolving the same in the fused electroylte in the furnace or added separately The exact amount or the mannerof adding the zirconium oxide is not material, but it 'is not necessary to use more than about,one-half percent of the total of aluminum ore used and a smaller proportion than this may be employed'if desired, provided the proportion of impurities, such as iron compounds, are small. For larger proportions of iron compounds, the proportion of zirconium oxide should be increased. y

Direct current is passed between the electrodes through the fused mixture to electrolyze and cause reductionof the aluminum ore and zirconium oxide, which finally results in the formation of a molten alloy of loy separates out at the .bottom of the furnace and ma be allowed to" run out through a tap hole tli any desired shapes.

As zirconium oxide is soluble in fused cryolite and. is more easily electrolyzed and reduced than alumina, the usual method of preparation, as-heretofore described, may be employed, merely adding a small proportion of zirconium oxide prior to or during the reduction process for the aluminum.

The function of the zirconium oxide is to provide a small proportion of zirconium in the resulting'product to neutralize the harmful effect of impurities, such as. iron especially, and make it possible to prepare aluminum alloys, which are substantially all aluminum, without the necessity of purifying aluminum ore of deleterious substances, before subjecting it to electrolysis. That is, a smallproportion of zirconium appears to neutralize a harmful effect of a much larger proportion of iron in the alloy and results in as good or better metal than pure aluminum.

An exampleof an alloy prepared according to my invention which is so -ductile and workable, that it was rolled into sheets .0015 thick, is as follows:

Aluminum about 96.4%; iron about 2.6%; silicon about .7%: zirconium about .3%. Such an alloy, although containing a very small proportion of zirconium, is much better than a corres onding alloy without zirconium, because t lacks brittleness, may be worked like andflis even stronger than pure aluminum, having a tensile strength ofabout 18,000 pounds per square inch before rolling. Without the zirconium content, such an alloy would be so brittle, that it would not be possible'to roll it or work it to a great extent.

With larger proportions of zirconium in the alloy, the increase in strength is more marked than with small amounts and the harmful effects of much larger proportions of impurities may be neutralized. Forexample an alloy prepared as above described,-

with the following composition:

Aluminum about 76%; iron about 13%; silicon about 2%; zirconium about 9%, was found to have a Brinell hardness of about 166, indicating a tensile strength correspond ing to that of steel or from 70,000 to 80,000

lbs. per square inch.

Although giving specific examplesfof alloys prepared according to andmethods of practicing my invention, I do notwish to I be limited thereto as they are merely illuserein and cast into pigs or in methods like that described in detail and employed without departing from the 'spirit and scope of my invention as defined by the appended claims.

What is claimed is: i 1. The manufacture of ductile aluminum- Zirconium alloys comprising the electrolysis I of an unpurified bauxite mixture with zirconium oxide, the proportion of zirconium alloy more than 10% of zirconium, fusing the mixture in an electric furnace and electrolyzing out a ductile aluminum-zirconium alloy.

3. The method of manufacturing aluminum-zirconium alloys com rising mixin impure bauxite with asma proportion o zirconium oxide having a zirconium .content insufficient to produce in the finished alloy .more than 10% of zirconium, dissolving in fused cryolite and electrolyzing the mixture in an electric furnace to form an impure aluminum with a small proportion of zirconium alloyed therewith, whereby a strong and ductile alloy is'produced.

{L'The method of manufacturing aluminum-zirconium alloys comprising fusing alkali and aluminum fluorides, dissolving impure aluminum and'zirconium ores therein in such pro ortion as to produce an alloy having more t an aluminum, up to 10% of zirconium and the remainder iron and silicon and electrolyzing out such alloy,

5. The method of manufacturing alloys comprising fusing alkali, alkaline earth and aluminum fluorides, dissolving impure bauxite or the like therein, dissolving zirconium oxide therein in such proportion as to produce in the finished .alloy a zirconium content upto 10% and electrolyzing out the aluminum-zirconium alloy- 6. An alloy of aluminum withfdeleterious impurities and a small proportion of zirconium, the aluminum predominating and the zirconium being present in such quantity that the harmful effect of the impurities-is neutralized.

-7. An alloy of aluminum, iron and zirconium the aluminum predominating. and the zirconium being present in such roportion that it neutralizes-the harmful e ect of the iron and a' ductile alloy is secured.

8. An alloy of aluminum, zirconium, silicon and iron with the aluminum predominating and the zirconium being present only in sufficient proportion to neutr'alizethe effect of the silicon and iron to result in the formation of a ductile metal.

' rat 9. An aluminum alloy comprisin from 2% to 13% of iron as impurity an being rendered ductile by containing zirconium in an amount less than that of the iron but sufiicient to neutralize the embrittling effect of the iron.

10. A ductile aluminum alloy of high tensile strength comprising about 75% to 98% aluminum, about 2% to 13% of iron and zirconium in an amount less than that of the iron but'suflicientto neutralize the embrittling effect of the iron.

11. A ductile aluminum alloy comprising from 75% to 98% aluminum, from. 13% to ll 2% of iron, .7 to 2% of silicon and from 9% to .3% zirconium.

1.2. An alloy of alummum, lron and Znstrength comprising 75% to num, about 13% of iron andabout 9% of ize the harmful' effect of; the iron and' strengthen the alloy.

13. An aluminum alloy 80% of alumizlrconium.

14. An aluminum alloy of im rov'ed strength comprising 75% to 80% o aluminum, about 13% of iron, about 2% of silicon and about 9% of zirconium.

In testimony whereof, I have hereunto subscribedmy name this 2nd day of November 1923.

HENRY-IRELAND RICHARDSON.

of improved-