US2338344A - Tungsten bronze article produced from metal powders - Google Patents

Description

Patented Jan. 4, 1944 TUNGSTEN BRONZE ARTICLE ruopucnn FROM METAL rowpnns Anthony. J. Marino, Weehawken, N. J., assignor to P. R. Mallory & 00., Inc., Indianapolis, Ind., a corporation of Delaware No Drawing. Application July 14, 1942, Q i

Serial No. 450,912

3 Claims. (01. 15-22) This invention relates to metal powder products and the method of making them.

An object of the invention is to produce metal powder products of predetermined density.

. Other objects of the invention will be apparent from the following descriptiomtaken in connection with the appended 5" The present invention comprises the combination of elements, methods of manufacture; and the product thereof brought out and exemplified in the disclosure hereinafter set forth, the scope of the invention being indicated in the appended claims.

While a preferred embodiment of the invention is described herein, it is contemplated that considerable variation may be made in the method of procedureand the combination of elements without departing from the spirit of the invention.

In making articles from pressed and sintered metal powders it is generally not possible to obtain a product having the same density .as wrought metal of the same composition. Even though extremely high pressures are used, the density of wrought materialscannot be obtained. {or some applications, such as for governors and governor weights, the density of the material is extremely important. Moreover, it would often be desirable to produce Jparts interchangeably from wrought metals or from pressed metal powder's without changing the mechanical design or proportioning of the parts.

The present invention contemplates the addition' of small quantitiesof high density metal, such'astungstemto apowdermixtureforuse in making a pressed powder product to adjust the density of the completed product to correspond to thatof wrought materials. r

As an example and preferred embodimentof the invention, it is contemplated that a pressed bronze powder product may be produced having a density corresponding to that of wrought To facilitate pressing, it is contemplated the. 0.5% of zincstearate by weight may be added to the above powder mixture and ballmilled with it for three hours.

The mixed and ballmilled powder may then be pressed into the shape desired with pressure suflicient to produce a presseddensity of approximately 6.5 gins. per c. c., or between 6.4 and 6.6

gm. per c. c.

The compacts thus produced are then placed on a graphite boat and pre-sintered at a temperature of between 400 and 450 0., preferably 425 0., for about one-half hour in a hydrogen atmosphere.

The compacts may then be sintered at a temperature of 800 C. or between 775 and 825 C. for one-half hour in a hydrogen atmosphere.

After sintering and cooling, the compacts are repressed under such pressure as to produce a finished density of 8.7 gms. per c. 0. plus or minus .05 gm. per 0. 0.

By the use of tungsten powder additions in this manner, it is readily possible to obtain a pressed powder product having the same density as one formed of wrought material of substantially the same composition and which can be used interchangeably with the wrought article.

While the present invention, as to its objects and advantages, has been described herein as carried out in specific embodiments thereof, it is not desired to be limited thereby bill; it is intended phosphor bronze. The wrought material has a density of 8.7 gms. per c. c.

In order to make a pressed powder product of similar density, it is contemplated that finely divided copper, tin and, tungsten powders be mixed-together in the following proportions:

Per cent.

by weight Copper powder--- 90.5 Tin powder 5.0

Tungsten powder... 4,5

-to cover the invention broadly within the spirit and scope of .the appended claims.

What is claimed is: v

1. 4i pressed and sintered metal powder article containing about 4.5% tungsten powder by weight, 5.0% tin by weight and 90.5% copper by weight and having a density of about 8.7 grams per cubic centimeter.

v 2. A governor weight w ht and 90.5% copper by weight and having a ensity of approximately 8.7 grams per cubic centimeter.

3. A sintered bronze article formed from metal powders and containingup to a few percent of .tungsten saidmrticle having a density substantially equal to that of wrought bronze free bi tungsten.

ANTHONY J. MAR-1N0.

formed of pressed, sintered'and repressed metal powders, composed of 4.5% tungsten powder by weight, 5.0% tin by,