US2211764A - Aluminum and chromium and zirconium alloy - Google Patents

Description

Patented Aug. 20,

UNITED STATES ALUDIINUM AND CHROMIUM AND ZIRCONIUM ALLOY Henry L. Coles, Boulder, 0010., assignor to William Sokolec, Chicago, Ill.

No Drawing. Application July 14, 1938,

Serial No. 219,156

6 Claims.

This invention pertains to an improved alloy and to a type of improved product made therefrom.

\ The novel alloy herein relates to alloys in which aluminum is present as a major constituent, and the preferred type of product is a cooking utensil.

Further, the novel alloy relates to aluminumchromium-zirconium alloys and to products made therefrom that have shown a very marked in: crease in corrosion-resistance, and toughness; and ability to be fabricated without deteriorating. Certain alloys and products made from those alloys have been placed on the market with assertions as to certain characteristics and abilities. It has been found, however, that the assertions have not been fulfilled. For instance, some of the products are represented as being noncorrosive, but it is found that they discolor, which is one form of corrosion, and that they pit and receive impurities in the pit holes and consequently are not desirable for many uses, especially for cooking utensils.

One of the features of this invention is to provide a new alloy and an improved product therefrom, both of which show a very marked increase in resistance to corrosion, and a particular value in toughness, and which have shown that very considerable working or fabrication thereof can be carried on without breaking the alloy or deteriorating the same, thus giving characteristics and abilities that withstand agreat deal of abuse in use without puncturing or bending to such an extent that deterioration sets in. In setting forth an example of the invention herein and of a particular example of a product, a cooking utensil has been selected, for the reason that the alloy and the product meet all of the requirements that are required in cooking utensils. The alloy is also capable of having many and exceptionally large uses in other in dustries or fields.

In the cooking utensil field or industry, exceptionally high resistance to corrosion is one of the first requisites, and then the ability to be sterilized to become perfectly clean for the storage,

cooking, and serving of food, and then the ability that will continue to be satisfactory under many 'uses, and the repeatings of those uses, is that which includes, in its final form, certain amounts of aluminum, chromium, and zirconium.

In the particular example herein of the elements or constituents of the alloy, which gives a most satisfactory alloy and product, chromium is present in approximately less than 1 per cent, and zirconium in approximately less than 1 per cent, and the remainder aluminum. Y It will be understood that certain impurities will be'present in trade form but which are usually considered as negligible.

Certain variations in the alloy have been found to be particularly valuable in different compositions. For instance, chromium is found to be satisfactory in quantities ranging between .60 and .90 per cent. A particularly good range of the chromium constituent has been found to be between .70 and .80 per cent. One of the best single amounts of chromium in the alloy is found and .58 per cent, and one of the single desirable percentages is, approximately .5 per cent. The variations in the chromium and zirconium do, of course, vary the amount of aluminum which makes up the remainder of the alloy.

When chromium is present in approximately .75 per cent, and zirconium in approximately .5 per cent, and the remainder aluminum, the resulting alloy has proven very advantageous, in that a very marked increase in the corrosionresistance has been noted, and that substantially the maximum toughness of an alloy of these constituents is obtained. In addition, the cooking utensil products made from the alloy are readily formed and fabricated without causing deterioration of the alloy.

In the method of producing the improved alloy and the preferred product it is desirable to alloy the aluminum, chromium and zirconium together in the most satisfactory manner to produce the advantageous alloy, and it is found that by melting aluminum 7 and adding thereto chromium oxide and zirconium oxide and allowing the reactions between these constituents to automatically take place, that a most satisfactory melt is obtained and poured and rolled, and formed into the final product.

In the preferred method it has been found desirable to make a mixture of the chromium oxide and zirconium oxide and then add this mixture to the surface of the molten aluminum.

' It is helpful to stir the oxide mixture into the molten aluminum at intervals to thus obtain a little more uniformity in'the alloy. This step, however, is not necessary.

As an example of the particular formation of the alloy, and the preferred product, approximately 100 pounds of aluminum of good purity, 99.4 per cent, or better, is melted; about 1% pounds of chromic oxide mixed with about three quarters to one pound of zirconium oxide and this mixture added to the surface of the molten aluminum, and reaction between the constituents then takes place to form a definite melt. This melt is then poured, but it is desirable to skim the slag therefrom, or to skim substantially all of the slag therefrom. After pouring, the metal is rolled to sheet, plate, or bar form, and is thereafter worked and fabricated, or formed into the particular design of cooking utensil desired.

It will therefore be seen from the foregoing description that a novel composition of aluminum, chromium and zirconium has been set forth in which there is, approximately, less than 1 per cent chromium, and approximately less than 1 per cent zirconium, and the remainder aluminum, and from this alloy produce a very advantageous type of cooking utensil. Such cooking utensils have shown marked resistance to corrosion, andadaptability to fabrication without deterioration, and to have exceptional toughness.

Certain modifications and changes may be made in the composition and method, but such modifications and changes are desired to be included Within scopes of the claims which follow.

I claim:

1. A metallic alloy composed of .60 to .90 per cent chromium, .3 to .6 per cent zirconium, and the balance aluminum.

2. A metallic alloy composed of .60 to .90 per cent chromium, .43 to .58 per cent zirconium, and the balance aluminum.

3. A metallic alloy composed of .70 to .80 per cent chromium, .43 to .58 per cent zirconium, and

the balance aluminum.

4. A metallic alloy composed of .60 to .90 per cent chromium, approximately .5 per cent zirconium and the balance aluminum.

5. A metallic alloy composed of approximately .75 per cent chromium, approximately .5 per cent zirconium, and the balance aluminum.

6. A corrosion-resistant, tough alloy composed of approximately 98.65 per cent aluminum, approximately .'75 per cent chromium, and approximately .6 per cent zirconium.

HENRY L. COLES.