US2768891A - Process for production of bronze alloys - Google Patents

Description

United States Patent PROCESS FOR PRODUCTION OF BRONZE ALLOYS Arthur George Gardner, methwick, near Birmingham,

and Thomas Stott Lister, Handsworth Wood, Birmingham, England, assignors to Wickman Limited, Coventry, England No Drawing. Application January 14, 1954;

Serial No. 404,122

i Claims priority, application Great Britain January 29, 1956 2 Claims. (Cl. 75-72) This invention relates to bronze alloys of a brittle character, and particularly such as are used as the bonding material in, for example, the manufacturing of grinding wheels containing diamond or other hard particles as the abrasive constituent.

For the above mentioned purpose it is essential that the bonding alloy shall be uniformly brittle, in order to permit release of the abrasive particles which have become dulled by wear, the release being effected by the crushing action exerted on the wheel when in normal use.

The object of the invention is to enable the above mentioned requirement to be met in a more satisfactory manner than heretofore.

The invention consists of a bronze alloy made from (essentially) copper and at least sufficient tin to produce an alloy having a proportion of delta phase, both the copper and the tin being in a powdered condition, and the tin, or both the tin and copper being initially in the oxide form, the alloy being produced by simultaneous reduction and alloying of the powdered constituents at a temperature below the melting point of the resultant alloy.

In one example, copper oxide derived from electrolytically prepared copper powder and fully oxidised, is comminuted in a ball mill and mixed with powdered tin oxide of good commercial grade, in the proportion in which the tin constituent is about 20% by weight of the combined copper and tin. The mixed powders are then placed in a loosely packed condition in a heat-resisting container, and are heated in a reducing atmosphere for about two hours at a temperature of about 500 C. This results in reduction and alloying of the constituents. The alloy is then allowed to cool to room temperature in the reducing atmosphere.

Owing to the simultaneous reduction and alloying of the constituents, the delta phase on which the brittleness depends is uniformly distributed throughout the final 2,768,891 Patented Oct 30, 1956 square inch to the desired form. Subsequently it is sintered at 500 C. in a reducing atmosphere. When the mixture has attained this temperature, it is transferred quickly to a press in which it is subjected to a pressure of from 8-30 tons per square inch. If desired any other hard abrasive material may be used instead of diamond.

Although it is preferred to use copper oxide and tin oxide of the quality mentioned this is not essential, as some degree of impurity of either constituent may be permissible. Further the extent to which the oxides are comminuted is not a critical condition.

In another example, powdered copper in the metallic state, and powdered tin oxide are treated in the manner above described, the final product having similar qualities to those of the first example.

The product obtained by the invention possesses the delta phase in a uniformly distributed condition, and is uniformly brittle.

The degree of brittleness can be varied by varying the proportion of tin to vary the amount of delta phase metal present in the product, but to ensure brittleness the proportions of tin oxide used should be sufficient for the bronze alloy to contain from 10-30% by weight of the tin constituent.

Whilst the invention is especially applicable for use in the manufacture of abrasive wheels, it may be applied to other uses where uniformity of brittleness is required.

Having thus described our invention what we claim as new and desire to secure by Letters Patent is:

1. A process for producing a bronze alloy from copper and at least suflicient tin to produce in the alloy a proportion of delta phase, consisting in comminuting copper oxide derived from electrolytically prepared copper powder, mixing the comminuted copper oxide with powdered tin oxide in the proportion in which the tin constituent is from 10-30% by weight of the combined copper and tin constituents, and heating the mixture in a reducing atmosphere for about two hours at a temperature of about 500 C. to elfect simultaneous reduction and alloying of the constituents.

2. A process for producing a bronze alloy from copper and at least sufficient tin to produce in the alloy a proportion of delta phase, consisting in mixing powdered copper in the metallic state with powdered tin oxide in the proportion in which the tin constituent is from 10- 30% by weight of the combined copper and tin constituents, and heating the mixture in a reducing atmosphere for about two hours at a temperature of about 500 C. to effect simultaneous reduction and alloying of the constituents.

References Cited in the file of this patent UNITED STATES PATENTS 1,829,635 Davey Oct. 27, 1931 2,645,573 Drapeaw et al July 14, 1953 FOREIGN PATENTS 3,962 Great Britain of 1874

Claims (1)

1. A PROCESS FOR PRODUCING A BRONZE ALLOY FROM COPPER AND AT LEAST SUFFICIENT TIN TO PRODUCE IN THE ALLOY A PROPORTION OF DELTA PHASE, CONSISTING IN COMMINUTING COPPER OXIDE DERIVED FROM ELECTROLYTICALLY PREPARED COPPER POWDER, MIXING THE COMMINUTED COPPER OXIDE WITH POWDERED TIN OXIDE IN THE PROPORTION IN WHICH THE TIN CONSTITUENT IS FROM 10-30% BY WEIGHT OF THE COMBINED COPPER AND TIN CONSTITUENTS, AND HEATING THE MIXTURE IN A REDUCING ATMOSPHERE FOR ABOUT TWO HOURS AT A TEMPERATURE OF ABOUT 500*C. TO EFFECT SIMLTANEOUS REDUCTION AND ALLOYING OF THE CONSTITUENTS.