US2253969A - Hard metal alloy for structures operating under pressure and/or sliding motion - Google Patents

Description

'could not be made alloys, due to freezing of the component parts.

Patented am, 1941 5 PATENT OFFICE METAL ALLOY For; smuc'runns omnmzrmc mums ranssnas AND/B snmmc MOTION Walther Dawihl, Kohlhasenbruck, near Berlin, German,

company, a corporation of and Adolf Fehse, General Electric New York ol'sto No Drawing. Application June 8, 1940, Serial No.

339,520. In Germany July 31,

. sclalms. (01308-242) In'cases where certain structures, such as shafts, stop rings of mechanical hammers and cams of valve shafts, wear their corresponding counterparts, such as hearing linings, chucks of rotatingmechanical hammers and tappets of internal combustion engines, by pressure and/or a' sliding motion, it is customary to use for such counterparts, hard metal alloys which have hi ductility and resistance to abrasion, for example cemented carbides such as sintered hard metal alloys consisting of tungsten carbides with an "addition of about 6. to 12% cobalt, iron or nickel. The parts working together with the counterparts niade. of such hard metal'alloys, however, out of the same hard metal The same thing happened if the percentage composition of the hard metal alloys used for the working parts and their corresponding counterparts was made difierent. On account of this 'difliculty the working parts of the corresponding counterparts of hard metal alloys which are being subjected to pressure and/or sliding motion, generally have been made of strong and hard steel, such as chrome nickel steel. However, as the hardness of all known steels is far below the hardness of the known hard metal alloys such as cemented carbides a rapid wearing of Y the steel working parts always had to be ac-.

cepted as unavoidable.

Extensive investigations have shown that the alloying, which causes the freezing, between the individual particles of rubbing bodies does not afl'ect in like manner all the substances'of which the hard metals are composed.- The particularlysurprising result was obtained, that the carbides of titanium, zirconium, vanadium, niobium and tantalum show a-very slight tendency to weld with cemented tungsten carbide. 'Iihis slight tendency to weld is shown by said carbides o! the fourth and fifth group ot the periodic system of elements, and as was found,'also by metallic chromium and chromium carbide, even when they have absorbed tungsten carbides in solid solution as combination crystals in their grids.

In accordance with the present invention, it is proposed to use hard metal alloys made of'mixtures of 30 to 95% tungsten carbide and 70 to of one or several carbides of titanium, zircdnium, vanadium, niobium, tantalum, chromium, or metallic chromium, for the working parts (for instance shafts) of combinations subjected to pressure and/or sliding motion, and to use hard metal alloyssuch as cemented tungsten carbide consisting of tungsten carbide and up to 20% of in addition to tungsteng-carbide, may be varied between 5 and 10%. The balance of tungsten carbide increases the ductility and tensile strength of the working parts.

Tantalum carbide may be added to the counterparts, in quantities of less than 5%, in order to increase their hardness. If particularly high demands are made concerning the tensile strength 0! the working parts, additions'oi metals with a lower elting point, especially of the iron group, may be made to the mixture of tungsten carbide andaforesaid carbides or metallic chromium. However, as these metals increase the tendency to freeze to the counterpart, the proportion of such metals with a lower melting point must not exceed 10%, and under no circumstances should it become equal to the conterits of the counterpart of metals with a lower melting Point.

The following tabulation contains recommended compositions of'the component working and counterparts:

What we claim as new and desire to secure by Letters Patent of the United States, is;

1. In combination, a bearing element and a cooperating counterpart element one of said ele ments consisting of a cemented tungsten carhide, the other element consisting of a hard metal alloy consisting of about 30 to 95% tungsten carbide and '70 to 5% of one or more of the carbides from the group titanium carbide, airconium carbide, vanadium carbide, columbium carbide, chromium carbide, the lower percentage 01- tungsten carbide being associated with the higher percentage of the carbides from sai group.

2. In combination, a bearing element and a cooperating counterpart element, one said elements consisting of a cemented carbide containing about to 15% metal of the iron group, about 5% tantalum carbide with the remainder tungsten carbide, the other element consisting of a sintered hard metal alloycontaining an appreciable quantity but less than of metal of the iron group the remainder of the alloy consisting of about 30 to 95% tungsten carbide and ll) to 5% of one or more carbides from the group titanimn carbide, zirconium carbide, va-

nadium carbide, columbium carbide, chromium carbide, the lower percentage of tungsten carbide being with the higher percentage of the carbides from said group. I

3. In combination, a sintered bearing element 5 and a cooperating sintered counterpart element,

one of said elements consisting substantially of tungsten carbide and up to about 20% lower melting point metal, said other element containing about to tungsten carbide and 70 to 5% of one or more carbides Irom the group titanium carbide, zirconium carbide, vanadium carbide, columbium carbide, chromium carbide, the lower percentage of tungsten carbide being associated with the higher percentage oi. one or more carbides 1mm said group.

DAWIHL. ADOLF FEHSE.