DE2035226B2 - USE OF A SINTERED ALLOY FOR WEAR RESISTANT, MECHANICALLY AND CHEMICALLY CORROSION HIGHLY STRESSED OBJECTS WITH LOW DENSITY - Google Patents

Description

Carbon,

Copper,

Niobium / tantalum

and / or titanium,

Molybdenum,

Boron,

Chrome,

Aluminum,

Manganese,

Tungsten,

Iron,

nickel

as a material for objects that, such as bearing materials used at high temperatures and such as grinding balls, high hardness, compressive strength and toughness, high wear resistance, good oxidation and must have corrosion resistance and low density.

2. Use of a sintered metal alloy according to

0 until 0.08% 0.2 until 1.8% 0.2 until 1.2% 0.5 until 29% 0.005 until 0.1% 0 until 23% 0 until 1.7% 0 until 1.9% 0 until 6.8% 0 until 68% 10 until 66%

Claim 1 consisting of 70 percent by weight titanium carbide with less than 0.01% free carbon and 30 percent by weight of an austenitic alloy with

16.8% Chrome, 16.8% Molybdenum, 4.7% Tungsten, 0.8% Copper, 0.3% Niobium, less than 0.03% Carbon, 0.02% Boron, Remainder nickel

for the purpose of claim 1.

3. Use of a sintered metal alloy according to claim 1, consisting of 70 percent by weight Titanium carbide with less than 0.01% free carbon and 30% by weight of an austenitic one Alloy with

less than 0.03% carbon,
18.0% chromium,
12.0% nickel,

1.0% molybdenum,

0.8% copper,

0.3% titanium,

0.01% boron,

Remainder iron

for the purpose of claim 1.

The invention relates to the use of a sintered metal alloy as a material for objects, the high hardness, compressive strength and toughness, great wear resistance, good oxidation and corrosion resistance, must have low density.

The object of the present invention is to find an alloy which, in addition to high wear resistance maximum toughness, good resistance to oxidation and corrosion and low Density. Further requirements are high compressive strength and hardness. Such demands will be z. B. placed on bearing materials that are used at high temperatures, or on materials for grinding balls.

Ceramic materials made from oxides, e.g. B. aluminum oxide, silicon oxide, metal carbides, e.g. B. tungsten-tantalum, Niobium, titanium or molybdenum carbide, or borides, nitrides and suicides fulfill one Part of the above-mentioned requirements, however, are too brittle, easily splinter, and their compressive strength and their wear resistance is insufficient. Pure Carbides are also too brittle and, in most cases, their density is too high. Cemented carbides, consisting made of metal carbides with metallic binders usually too high a density and insufficient corrosion resistance. Borides, nitrides and suicides as individual components are as brittle as glass and therefore for the purpose of the present Invention also unsuitable. Due to insufficient compressive strength, metal alloys achieve and Hardness does not have the desired properties.

Also the sintered carbide hard alloy known from US Pat. No. 3,450,511 from 25 to 75% titanium carbide and 15 to 75% of an austenitic or by conversion and / or Precipitation of intermetallic phases of hardenable steel containing 1.2 to 15% manganese, the high Wear resistance, in particular friction and erosion wear resistance, with high hardness, fulfilled not all of the above-mentioned requirements, and above all it does not have sufficient resistance to oxidation and corrosion and not a sufficiently low density.

To solve the problem on which the invention is based, when using a sintered metal alloy, consisting of 55 to 80 percent by weight of one or more carbides of titanium, chromium, vanadium, as single or mixed carbides and 20 to 45 percent by weight of an austenitic metal alloy with

0 to 0; 08% carbon,

0.2 until 1.8% Copper, 0.2 until 1.2% Niobium / tantalum and / or titanium, 0.5 until 29% Molybdenum, 0.005 until 0.1% Boron, 0 until 23% Chrome, 0 until 1.7% Aluminum, 0 until 1.9% Manganese, 0 until 6.8% Tungsten, 0 until 68% Iron, 10 until 66% nickel

proposed for the purpose mentioned above. The above area becomes the use an alloy of the following composition is preferred: 70 percent by weight of titanium carbide with less

as 0.01% free carbon and 30% by weight of an austenitic alloy

16.8% chromium,
16.8% molybdenum,

4.7% tungsten,

0.8% copper,

0.3% niobium,
less than 0.03% carbon,

0.02% boron,

Remainder nickel.

Another preferred alloy to be used consists of 70 percent by weight titanium carbide with less than 0.01% free carbon and 30 percent by weight an austenitic alloy with

less than 0.03% carbon,
18.0% chromium,
12.0% nickel,

1.0% molybdenum,

0.8% copper,

0.3% titanium,

0.01% boron,

Remainder iron.

The density of the aforementioned preferred alloy is 5.80 g / cm ³ , the hardness 70 to 72 HR _C , the compressive strength 300 to 350 kp / mm ² , and the corrosion resistance, especially under reducing conditions, i.e. to halides, to acidic chloride solutions and Hydrochloric acid was present. The toughness of the sintered metal alloy to be used according to the invention was tested on sintered balls which were thrown or hurled onto a concrete slab from a height of 10 m. It was found that the balls, without showing the slightest tendency to splinter, jumped back to the starting height.
The production of the invention to be used

.. the sintered metal alloy takes place in a manner known per se by mixing the ground to a maximum of 6 μm Alloy components, i.e. the carbide component and the individual elements or else Pre-alloys of the binding metal alloy, wet grinding ζ. B. in attritors to a particle size of max. 3 μΐη

ίο with a large proportion of fine grains and subsequent drying and expulsion of the grinding liquid in a vacuum dryer. After kneading the mixture again with the addition of additives that facilitate the pressing, which are also sufficient to granulate the finest powder for better flowability, the granules are pressed on mechanical or isostatic presses to form molded bodies, which are then placed in a vacuum sintering furnace under a pressure of less than 10 ~ ² Torr a temperature of about 1250 to 1350 ⁰ C for a time sufficient for heating, holding and cooling of about 8 to 48 hours with alloy and mixed crystal formation.
Due to the aforementioned good properties of the sintered metal alloy of the above composition, it is suitable for. B. as a material for grinding balls, which are used in a neutral, oxidizing or corrosive atmosphere, even under the influence of heat up to about 800 ° C, further as a material for parts that are used at high temperature, e.g. B. ball bearings, roller bearings, thrust bearings, slide rails, gas bearings. Due to the austenitic structure of the binding metal alloy, it can also be used for parts that do not have to be magnetizable, e.g. B. for punches or dies of presses that are used in a magnetic field.

Claims (1)

Patent claims: 1. Use of a sintered metal alloy, consisting of 55 to 80 percent by weight of one or several of the carbides of titanium, chromium, vanadium as single or mixed carbides and 45 bis 20 percent by weight of an austenitic metal alloy with