DE2009696A1 - Masses of aluminum oxide and metallic compound connected by intermetallic compounds - Google Patents

Description

Masses connected by intermetallic compounds made of aluminum oxide and metallic compound

Alumina cutting tips are known. These tips or cutting heads have the advantage of extreme hardness and abrasion resistance as well as superior flexural strength. They are resistant to erosion and show little welding or diffusion between the waste chips and the tip * They are also resistant to oxidation. However, these advantages are largely due to its brittleness and the lack of toughness in ceramic cutting heads and a pronounced tendency to stress cracks and eruptions canceled.

Many attempts have been made to combine alumina with materials which mitigate these disadvantages, while the advantages of pure alumina are not noticeably reduced . Often aluminum oxide is combined with up to JO to AO % of a metal in order to

009818/193

to increase strength and toughness. These crowds in general with ceramic-metal composites (cermets) "are called, give better thermal conductivity than pure alumina ceramics as well as increased strength. However, the presence of the metal provides a reduction the overall abrasion resistance of the cutting head.

The addition of carbides to metal-alumina masses was another development aimed at increasing abrasion resistance and hardness accompanying the presence of the metal. However, even these combinations of alumina, carbides and metal (1) bring poor abrasion resistance due to the metal and (2) brittleness and poor thermal shock resistance due to the Difference in the thermal expansion coefficients found in such mixed refractory materials be with yourself.

It has been found that certain masses of aluminum oxide and certain carbides and nitrides that are associated with a intermetallic compound, suitable for the production of cutting heads with unusual properties are. These masses can be used to make a cutting tip with an unusual combination of hardness and Strength and with very great resistance to wear and thermal shock. Furthermore the dense compositions of the invention are useful as oxidation-resistant and chemically-resistant building materials.

The invention relates to dense masses with an average particle size of less than 1On, which is made up of two interpenetrating three-dimensional network structures or networks are built up; a network structure consists essentially of

- 2 009838/1937

. ■ · .ο

Aluminum oxide j and the other network structure "consists essentially of from a metallic compound (metalline)

■ ".- ■ - titanium carbide,
Titanium nitride,
Zirconium carbide,. ' - zirconium nitride, niobium carbide,
Niobium nitride,
Tantalum carbide,
_f tantalum nitride, ■

or mixtures thereof;

and an intermetallic compound

. Iron aluminide,

Iron titanide, "■ - ■ cobalt aluminide,

Cobalt titanide, ·. '.' Nickel aluminide,

Hiickitanidj. ■

Tungsten aluminide, molybdenum aluminide, niobium aluminide, ■ _: "· tantalum aluminide, '

Titanium aluminide, . Zirconium aluminide,

or mixtures thereof,

wherein said alumina is present in an amount in the range of 20 to 80 vol.%, _see the intermetallic compound is present in the metallic compound in an amount ranging from 10 to 78 vol.% and in an amount in the range of 2 to 30 vol.% , with the proviso that the volume percentage of the metallic compound must be less than the volume percentage of the intermetallic compound.

- 3 009838/1937

Surprisingly, these dimensions result in extraordinary Advantages over similar masses consisting of closely related compounds and against hating the same compounds in different amounts. The compositions according to the invention are the result of these exceptional properties Suitable for cutting and milling ferrous alloys even at very high cutting speeds.

The drawing .-- gives a graphical representation of the quantities of the Again ingredients encompassed by the compositional limitations of the invention. Area A is the Area in which the'relations of composition within Be within the limits of the invention, Range B is the range in which the proportions of the composition are within the preferred limits of the invention are ^ and range C. is the range in which the proportions of the composition are particularly preferred. The one in the graph The percentages shown are percentages by volume.

The highly heat-resistant, tough compositions of the invention consist essentially of aluminum oxide, a metallic one Compound (metalline) and an intermetallic compound.

(a) alumina

The aluminum oxide is present in the compositions according to the invention in amounts in the range from 20 to 80% by volume. The requirement that at least 20 % aluminum be present is based on the desire to have the aluminum oxide present as a continuous phase . Alumina amounts below 20 % are less satisfactory because at these low values the aluminum phase tends to be discontinuous. The presence of at least 20% by volume alumina provides continuity

009838M937

of the aluminum oxide phase under the usual conditions.

On the other hand, the amount of aluminum oxide is limited to 80% by volume, because more aluminum oxide tends to reduce the continuity of the electrically conductive phase of the metallic and'intermetallic Prevent connection.

It is preferred that the aluminum oxide in the composition according to the invention in amounts in the range from JO to 70% by volume and particularly preferably in amounts in the range from 4-0 to 60% by volume is present because such amounts are actually continuous phases of alumina and the electrically conductive phase to guarantee.

Alumina suitable for use in the compositions of the present invention can be in many forms so long as it is finely divided. It can therefore be in the form of γ-, ^ - or α-aluminum oxide or mixtures thereof. α-Alumina is a preferred starting material because it does not have as high a specific surface area as γ- or ^) -alumina and is likely to contain less adsorbed water, which can be harmful. . . "

The aluminum oxide to be used should be sufficiently finely divided to produce the masses according to the invention with an average grain size of less than 10% . to surrender. A suitable starting aluminum oxide is α-aluminum oxide with a specific

p "

see surface area greater than 2 m / g and preferably 5 to 25 egg / g. Alumina with an outermost crystallite size of less than 0.5 µ as measured by the X-ray line broadening technique is particularly preferred. Such an aluminum oxide can most easily be obtained by using anhydrous aluminum diacetate 5 or more. Is heated at 1200 ° C for hours. .

An example of a suitable commercially available alumina is Alcoa Superground Alumina XA-I6, which is based on Because of X-ray examination as α-aluminum and it has a specific surface area of about 13 m / g> which is equivalent to a spherical particle size of about 115 nmi.

(b) carbides or nitrides (metallic compounds, metallines )

The metallic compound is used in the compositions according to the invention used in amounts ranging from 10 to 78% by volume and consists of titanium carbide, titanium nitride, zirconium carbide, zirconium nitride, Niobium carbide, niobium nitride, tantalum carbide, tantalum nitride or mixtures thereof.

If zirconium carbide or zirconium nitride is used, a small amount of hafnium carbide or nitride (i.e.

1 to 5% by weight, usually about 2 %) , which is usually present as an impurity in technical zirconium compounds.

Preferred amounts of metal compound are in the range of 15 to 4-5% by volume, and the most preferred amounts are in the range from 20 to 40% by volume. These amounts are most effective at contributing to properties such as hardness and wear resistance, in the compositions of the invention.

The metallic compounds are commercially available or they can be prepared by known methods. The metallic compounds should preferably have a particle size of less than 5 a. and more preferably less than

2 ü. exhibit. If the starting material has a particle size much larger than 5 J * ", it can be used to reduce

- 6 -009838/193 7

change its particle size to the acceptable size will, of course, result in the milling of the invention Components, which is carried out to achieve a high degree of homogeneity, to a certain extent Pulverization of the carbide and the other components. '. ;

Titanium nitride, titanium carbide, zirconium nitride and zirconium carbide are preferred for use in the compositions according to the invention, since they are readily available. Masses with an excellent balance of physical properties result and when used for cutting or grinding ferrous alloys develop great effectiveness.

(c) Intermetallic compound

The intermetallic ones suitable for use according to the invention Compounds consist of iron aluminide, iron titanide, Cobalt aluminide, cobalt titanide, nickel aluminide, Nickel titanide, tungsten aluminide, molybdenum aluminide, niobium aluminide, Tantalum aluminide, titanium aluminide, zirconium aluminide or Mixtures of these. The intermetallic compounds should be present in amounts in the range from 2 to 30% by volume. At least 2 vol.% Is necessary to have any noticeable bond in to give to the body, and to give in larger quantities than these added strength and toughness, although the abrasion resistance decreases. Little occurs above JO VoI,% further improve the strength. However, the abrasion resistance is considerably lowered.

If zirconium aluminide or zirconium titanide is used, it can contain the usual amounts of hafnium, ie 1 to 5 % by weight .

- 7 ■■ - 009 836/1937

Preferred amounts of intermetallic compound are 3 "to 25% by volume and more preferably 4 x to 20% by volume, since over this Areas the best balance between strength, toughness and abrasion resistance was obtained.

The preferred intermetallic compounds are the aluminides, and the most preferred intermetallic compounds are iron aluminide, cobalt aluminide and nickel aluminide, because they rely on the highly heat-resistant, intermetallic binders used in the compositions according to the invention that are the most ductile.

Aluminides of nickel, molybdenum and niobium, which are produced by the Cerac, Inc.; Iron aluminide available from Shieldalloy Corp. iron titanide is available from Shieldalloy Corp. or Fotte Mineral Co. and nickel titanide from Metal Hydrides, Inc. can be used. The intermetallic compounds can also be synthesized in situ "by adding the correct ratio of elements in the powder from which the dense body of the invention are made, are mixed together.

The intermetallic compounds can be synthesized by changing the stoichiometric ratio of the components are fused together in an inert, refractory crucible in a vacuum furnace. After cooling, the solid can Melt from the intermetallic compound repeatedly broken open in a hammer mill and in a ball mill ^ be ground to a fine particle size. A fine powder can also be obtained by making the molten one intermetallic compound is atomized by known methods for producing atomized metal powder. Although Powder with a particle size below 0.29 nut (minus 50 mesh, U.S. Standard Sieve Series) for the production of the

- 8 009838/1937

4234-G. . 3

inventive compositions can be used Powder with a particle size below 0.074 mm (minus 200 mesh) preferred, and powder with a particle size below 0.044 mm (minus 325 mesh) is particularly preferred. '.

The fine intermetallic ones prepared as described above Powders can then be used in the compositions to be used for the production of the dense bodies according to the invention be incorporated.

· ■■■ - ■ ^: ^ ■■ """■" t

The constituents used in the compositions according to the invention should be essentially pure. It is desirable to remove impurities, such as oxygen, to exclude, -der tends to adversely affect the dense compositions of the present invention.

However, small amounts of many impurities can be tolerated without noticeable loss of properties.

Thus, the intermetallic compounds can be small amounts of metals such as titanium, zirconium, tantalum or niobium as minor impurities, although low-melting metals such as lead should be excluded. Small amounts of others, from titanium, zirconium, Niobium or tantalum carbide different carbides, for example a few percent tungsten carbide, which are sometimes added during grinding can be present. Even small amounts of oxygen can be tolerated, for example occur when titanium carbide has been exposed to air is, resulting in a few percent titanium oxycarbide. ' However occurs after the powder components are ground together, have been and are in a highly active state,

- ■ ■. - _ 9 - -..- ■■■■■ Q0983871937 ° "

G AO

easy oxidation, especially of the intermetallic compound one and should be avoided.

Structural properties

Except for the characterization of the compositions according to the invention On the basis of the components discussed above, the compositions can also be based on their structural properties be characterized.

(a) Mutual penetration of three-dimensional networks

The masses of the invention are characterized in that they are two mutually interpenetrating three-dimensional Network structures contain: one made of aluminum oxide and one made of intermetallic bonded carbide or nitride.

Although the effects of the presence of these two crosslinks is not fully understood, it is believed that they contribute significantly to the unusual properties of the masses according to the invention, resulting in masses, which are stronger and more impact resistant than common ceramic alumina cutting tools are.

The existence of this simultaneous, continuous network structure can be determined from the analysis of the dense mass. The continuity of the network structure made of aluminum oxide can by removing the metallic and intermetallic compounds by anodic etching in 10% ammonium bifluoride solution be determined. The process, although it does not visibly affect the appearance of the mass, removes it the electrically conductive material from the outer area of the masses closest to the surface and results a non-conductive surface with an electrical resistance

- 10 009838/1937

4234-G. M.

stood by more than 100,000 micro-ohm-centimeters. The proof The continuity of the alumina phase "consists in the solid, coherent surface, which in spite of the obvious Removal of conductive materials.

A "convenient way to remove all metal connections and intermetallic compounds from the invention according to masses in order to prove the presence of a three-dimensional framework made of aluminum oxide, "consists in

that small sticks from the mass into a mixture of 25 car 12% hydrofluoric acid and 5% concentrated nitric acid be immersed. A stick of 0.17 x 0.17 χ 2.5 cm can be left in the acid mixture for 24 hours. while the mixture is heated on a steam bath. The portion of the rod that remains after 24 hours consists of Alumina and can in terms of continuity and strength examined by usual means.

The inventive. According to the above analysis method, masses which contain 40% or more by volume of aluminum oxide produce very strong aluminum frameworks. An aluminum framework obtained from a composition according to the invention which contains about 60% by volume of aluminum oxide retains a transverse breaking strength of 1050 kg / cm (15,000 psi). The presence of aluminum. Nium oxide in amounts of about 30% by volume tends to produce a reasonably strong framework with transverse rupture strengths of about 100 kg / cm (1400 psi). At about 20 vol.% Alumina is usually a weak However, self-supporting structure in front of, and below 20 vol.%, There is often little or no continuous alumina ^r backbone. The removal of the electrically conductive phases from the compositions containing less than 20% by volume of aluminum oxide usually leads to the recovery of aluminum oxide powder.

009838/1937

The presence of a continuous phase of the electrically conductive metallic compound and intermetallic compound can be seen from the electrical conductivity of the hot-pressed compositions according to the invention. The inventive Compounds preferably have an electrical resistivity of less than about 1 ohm-cm, more preferably less than about 25,000 micro-ohm-cm, and more preferably less than 5000 micro-ohm-cm. The preferred crowds of the invention in which the metallic compound plus the intermetallic compound make up 35% by volume or more, often have an electrical resistivity of less than 1000 micro-ohm-cm.

(b) coefficient of thermal expansion

The compositions of the invention are also characterized by having two continuous interpenetrating crosslinks with very similar coefficients of thermal expansion. In general, the coefficient of expansion of the aluminum oxide phase and of the metallic and intermetallic phases is between 10 10 "and 13 χ 10" cm / cm / 0.5 ° C (4 10 ~ ⁶ and 5χ10 ~ ⁶ inches / inch / ° F) at temperatures from room temperature up to 540 ° C (1000 ° F).

Due to the similarity of these heat coefficients, Cutting tips made from the masses according to the invention, extreme temperature changes with little or no produced in the mass withstand thermal deformation. The masses are very resistant to thermal shock, both in terms of bursting as well as surface cracking.

(c) Homogeneity and fine-grain structure

The masses according to the invention are also characterized by

- 12 009838/1937

4234-G

net that they have a fine average particle size of less than 10u and - preferably - less than 5 microns mean grain diameter. The number of mean grain size and the size distribution result from enlarged electron micrographs of polished, etched surfaces using an extension of the methods of John E. Hilliard, which are in "Metal Progress", May 1964, pages 99 to. 102 and by R. L. Pullman, in the Journal of Metals, March 1953> page 447 ff ". The grain size is uniform and homogeneous over the entire mass, and there is practically no porosity in the dense masses of the invention. The distribution of the co-existing continuous phases (i.e. alumina framework and the metallic-intermetallic matrix) is also uniform and homogeneous, and in general terms, any area of 100 a square, examined microscopically at 100X magnification, appears to be like any other area of 100 yes squared within the usual statistical distribution limits. The fine grain size of the compositions according to the invention is of course at least partially responsible for the continuity of the interpenetrating phases (ie aluminum oxide framework and the metallic-intermetallic matrix). However, together with the homogeneity and the low porosity, it also contributes to the abrasion resistance of the compositions according to the invention. Metal inclusions, such as the carbide inclusions in cast iron, will abrade even the toughest of metal-bonded carbide cutting tools. Nevertheless, the compositions according to the invention are extremely resistant to abrasion. ,

Manufacturing

The production of the inventive compositions is important

- 13 -009838/1937

because many properties of the masses are achieved as a result of the manner in which they are made. Hence stand the use of fine-grained starting materials and thorough grinding of the mixed components in direct Relationship to the fine grain size and the uniform Homogeneity of the masses. Others "in the preparation of the inventive There are masses of observable precautionary measures that have significant effects on the products the following:

(Ό preventing excessive contamination from the Grinding media and moisture or oxygen in the Air,

(2) hot pressing or sintering under conditions that allow volatile materials to escape prior to densification allow,

(3) Avoid excessive absorption of carbon from hot press molds by removing their. Contact under absorption-demanding Conditions is limited, and

(4) Avoiding Excessive Components — Recrystallization and resulting excretion by prolonged exposure to very high temperatures is avoided.

(a) marriage; and PowderRewinnunp;

The grinding of the components in order to mix them homogeneously and to achieve very fine grain sizes it is carried out according to the usual • procedures. Close optimal milling conditions usually a milling device which is half-filled with a milling media such as cobalt bonded tungsten carbide balls or rods, is a liquid medium, such as a hydrocarbon oil, an inert atmosphere, Meal rooms from a few days to several weeks

009838/193 7

4234.G ■ j-

and the recovery of powder also in an inert atmosphere a. The powder obtained is usually "dried at temperatures of about 150" to 200 ° C under vacuum "" and then sieved and stored, if necessary in, an inert atmosphere.

(b) solidification "

The compositions according to the invention are usually to be dense, solidified pore-free bodies by sintering under pressure. Solidification or densification is usually accomplished by hot pressing the mixed powders in a graphite mold under vacuum carried out. '■'

For hot pressing, the powders are brought into the mold and into the heated zone of the hot press without the use of Pressure introduced so that volatile impurities can escape before the mass is compacted. Full pressure is usually applied at or near the maximum temperature.

The maximum temperatures are between 1400 and 19OQ ⁰ Oje on the amount of the present intermetallic compound, and they are usually 1600-1800 C. maximum pressures are in the range of 35 "to 280 kg / cm (500 to 4000 psi), wherein, lower pressures are generally used in combination with lower temperatures for compositions with a high content of intermetallic compound, and conversely, high pressures and temperatures are used for compositions with a low content of intermetallic compound.

As can be seen, tend at higher temperatures and pressures some of the lower 'melting intermetallic constituents for squeezing or squeezing out of the masses during

- 1-5 -. 009838/193 7

of the compression process. This tendency can be beneficial to this used that one with a slightly larger than the desired amount of intermetallic compound begins and works at high temperature and high pressure. By doing this, part of the intermetallic compound becomes squeezed out and gives the desired content of intermetallic compound, and the precipitated intermetallic Compound serves as a lubricant and sintering aid. while of the pressing process. This way there can be gaps or Gaps can be eliminated despite the highly heat-resistant nature of the final mass.

It is important that the mass is not heated to a temperature or for a period of time higher than that required to eliminate porosity and achieve density. These higher temperatures or longer periods of time lead to undesired grain growth and result in a coarsening of the structure and can even to the development of secondary porosity due to recrystallization or to the formation of undesired phases to lead.

As set out below, press temperatures are usually used in the range of 1700 to 1900 ° C 'for the preferred products of the invention "and the maximum temperature is used for less than JO minutes, usually not more than 10 minutes and preferably not more than 6 minutes, after which the product is removed from the hot zone. The masses according to the invention are compressed by these measures or compacted so that porosity is eliminated and maximum density is achieved without excessive recrystallization will. These products are characterized by their fine grain size and exceptional resistance to cracks.

- 16 009838/1937

4234-G '

The compositions according to the invention, in particular those with a high Content of internal metallic compounds and small particle sizes, can also be densified by cold pressing and sintering under high vacuum, provided that the the above limitation with regard to the minimum of the sintering time at the maximum temperature is met. It is preferred that. Powder in a closed rubber mold that is immersed in water an isostatic press capable of using high hydraulic pressures (4220 kg / cm, 60,000 psi) is hung to press isostatically. ,

Usability '^

The compositions according to the invention can be used in a wide variety of types of cutting tools which are used for numerous purposes are designed to be used. You can go to standardized, interchangeable inserts suitable for turning, drilling or milling, shaped or cut. Or you can use metal-bonded carbides or tool steels for Nachschied'fwerkzeuge under visual formation or connected in other ways. They are generally suitable for removing metal from ferrous metals, including for machining or cutting hardened steels, alloy steels, m'araging steels, cast iron, cast steel, nickel, nickel-chromium alloys, nickel-based alloys and cobalt superalloys as well as for Cutting of non-metallic materials such as fiberglass-plastic laminates and ceramic masses.

The compositions according to the invention are best suited for cutting such metals at very high speeds, e.g. B. Alloy steels at 240 surface meters / minute (800 surface feet per minute) and cast iron at 360 surface meters / minute (1200 surface feet per minute). This is

9838/1937

rests on "the great resistance to Kraterbildimg and hand wear and that the invention Masses retain good hardness at elevated temperatures. They are special because of their good resistance to shock well suited for making repeated short cuts or other intermittent cutting operations where the temperature of the cutting edge changes rapidly.

The compositions of the invention can also be used for general high heat resistance Applications are used, e.g. for thread guides, bearings, wear-resistant mechanical parts and as pre- or grinding dust in grinding wheels and cutting knives bonded with resin. In addition, the inventive Masses suitable for any application in which their combination of highly heat-resistant properties, electrical conductivity, metallophilic nature and resistance to thermal shock provide an advantage, for example for the production of an electrically conductive ceramic-like Grinding sand for grinding wheels used for electrolytic Loops are used.

The objects according to the invention are extremely durable against oxidation at high temperatures, and this property together with their electrical conductivity at night it is possible that they can be used as furnace heating elements that keep their high temperature in for long sidewalls can maintain oxidizing atmospheres.

Their resistance to oxidation and their excellent hot hardness make them particularly suitable as building materials for High temperature extrusion molds are suitable.

The invention is described in more detail by means of the following examples.

- 18 -

009838/1937

IAD

. Example 1 . "'.."'"""- ■ '''"

This is an example of a composition containing 50 % by volume of aluminum oxide, 45% by volume of titanium carbide and 5% by volume of nickel aluminide *

The aluminum oxide present in the form of very finely divided α-aluminum oxide is produced from colloidal boehmite according to US Pat. No. 2,915,475 by heating the starting material in air at 550 ° C. for 20 hours, then increasing the heat to 500 ° C. and is kept at this temperature for 15 hours and finally the heat is increased at about 100 ° C per hour to a final temperature of 124-0 ° C, at which the material is kept for 3 days. A sample of the cooled product is then thrown . treated with "hydrofluoric acid and is 88.5 % in 24% aqueous hydrofluoric acid for a period of

'".. oxide

Insoluble for 16 hours, resulting in an α-aluminum content of about 88.5%. The specific surface area of the insoluble in hydrofluoric acid, aluminum oxide is 6.3 m / g as measured by Stickstoffadsoi ^v ption using the Brunaaer, Emmett, Teller method.

This surface area corresponds to one crystallite size of ά-alurainium oxide with an average particle diameter of about 240 μm. Under an electron microscope the cc- ^ appears Aluminum oxide as aggregates of aluminum oxide crystals in the Range from 100 to $ 00 mia in diameter. '

The density of the free flowing finely divided α-alumina is 0.5 g / cm ^, which is obtained by measuring the volume of a weighed sample after inclusion in a 100 cm glass cylinder was obtained.

The titanium carbide to be used has a nominal particle size

- 19 009838/1937

to

of 2 ia and a specific surface area of 3 m / g, determined by nitrogen adsorption. An electron photomicrograph shows that the titanium carbide grains are about 2 × 2 in diameter and that they are bundled in the form of loose aggregates. The carbon content is 19.0 / y, and the oxygen analysis shows a titanium dioxide content of about 2.5 %

The nickel aluminide to be used has a particle size such as that it passes completely through a sieve with sieve openings

of t \ A- ii (325 mesh) passes through. The specific surface

/ ρ

The range of the powder is 0.3 m / g, determined by

nitrogen adsorption. This specific range corresponds to particles of nickel aluminide of about 3, A- yes. mean particle diameter. The oxygen content is 0.5%.

The powders are milled by placing 4,000 grams of preconditioned cylindrical cobalt-bonded solid carbide inserts 6.3 mm (1/4 inch) in length and 6.3 imi (1/4 inch) in diameter in a 1.3 liter steel roller mill about 15 cm (6 inches) in diameter are given in the well 375 ^m l "Soltrol" (a saturated paraffinic hydrocarbon having a boiling point of about 175 ° 0) have been introduced. ^{59:75 S d-eG} α-aluminum oxide, 67 »50 g of the titanium carbide powder and 8.78 g of the nickel aluminide powder, as described above, are then introduced into the mill.

The mill is then closed and rotated at 90 rpm for 5 days Rotation offset. Then the mill is opened and the contents through a sieve with sieve openings of 2.83 mra (No. 7) emptied while the grinders are held inside. The mill is then rinsed several times with "Soltrol" 130, until all ground solids are removed.

- 20 009838/1937

The ground powder is transferred to a vacuum evaporator, and the excess hydrocarbon is after that suspended material has settled, decanted off. The moist residue cake is then placed under vacuum and under application dried by heat until the temperature inside the evaporator is between 200 and 300 ° 0 and the pressure is less than about 0.1 mm Hg. After that the powder is under handled with complete exclusion of air. '

The dry powder is passed through a sieve with sieve openings 0.4-2 mm (40 mesh) was passed through in a nitrogen atmosphere and then under nitrogen in sealed plastics it keeps it stored.

A compacted block is made from this powder, by placing the powder in a cylindrical graphite mold with a square recess of 27 x 27 mm (. 1 1/16 χ 1 1 / 1-6 inches) and those with opposite narrow pass

is fitted with the flask, hot-pressed ^ A flask is held at one end of the mold cavity while 25g of powder is poured into the cavity under nitrogen and distributed evenly by rotating the mold and tapping the side lightly. The upper piston is then brought into position with hand pressure. The assembled mold and contents are then placed in a vacuum chamber of a vacuum hot press, the mold is held in a vertical position and the pistons extending up and down are placed between opposing dies of the press under a pressure of about 7 "to 14 kg / cm ( 100 to 200 psi). Within a period of 1 minute, the mold is raised into the hot zone of the oven at 1500 ° C and the oven temperature is increased immediately, while the positions of the ram are set so that further movement during the heating period ver

- 21 009838/1137

4-234-G

is prevented. The temperature is increased from 1500 to 1800 ° C in Increased 10 minutes, and the temperature of the mold is then at 1800 ° C held for a further 2 minutes in order to achieve a uniform temperature Ensure heating of the sample. A pressure of 280 kg / cm (4000 psi) is then applied through the Piston applied. Immediately after the pressing process, the form with content that is still between the opposite Press ram is held, conveyed from the oven into a cooling zone, where the mold with contents on dark egg heat in refrigerated for about 5 minutes.

The form and contents are then removed from the vacuum oven, and the block is removed from the mold and sandblasted to remove any adhered carbon.

The compacted good or the block, the -ems- a. 27 mm (1 1/16 inch) square, about 7 ₅ 6 mm (0.30 inch) thick, is cut so that a piece slightly larger than 1.3 mm square (one half inch square) is removed from the center. 1.8 mm (0.070 inch) thick strips are cut from the material that remain on each side of the center piece and further become 1.8 1.8 mm square (0.70 inch χ 0.70 rods inch square) to test the transverse breaking strength. Other parts of the block are used for ball indentation hardness tests and for other product characterizations. The transverse breaking strength, as measured by bending the test bars 1.8 1.8 mm (0.070 χ 0.070 inch) with a span of 14.3 mm (9/16 inch), is 11,600 kg / cm * (I65 000 psi). The hardness is 93 »2, based on the Rockwell A scale.

The square center piece becomes a cutting point with exact dimensions of 12.7 x 12.7 x 4> 7 mm (1/2 χ

- 22 U9838 / 1937

42J4-G '

1/2 χ '3/16 inch) and the corners are finished with Surface machined to a radius of 0.79 mm (i / 32 inch.), a version known in the industry as the SNG-432 is. This point is used as a single tooth in a 4-inch (10 cm) diameter burr to remove rods 4-34-0 steel (R 36) with a width of 5 cm (2 inches)

a surface speed of 160 m / min (535 feet per minute) and a feed rate of 0.135 (0.0053 inch) per tooth with a cutting depth of 2.5 (0.100 inch) to be milled dry face to face on the center point.

The milling process is continued under these conditions for a rod length of 91 cm (36 inches) and upon inspection the cutting tip ₍ showed an even flank wear of only 0.13 mm (0.005 inch) and local flank wear of 0.20 mm (0.008 inch) with no pitting on the surface of the tool and no chipping or chipping of the corners or edges. Under the same cutting conditions, commercial ceramic cutting inserts chipped and cracked after a cut of 5 to 28 cm (2 to 11 inches).

The tip is also used as a cutting tool for gray cast iron grade 30 (170 BHE) in a high speed rotary test at 375 surface meters per minute (1250 surface feet per minute) using a feed of 0.13 mm (0.005 inch) per revolution and a cutting depth of 1.3 mm (0.050 inch) is used. After 10 minutes of operation, the tip showed uniform flank wear of only 0.10 mm <(0.0o4-inch). ; .

It was found that under the same conditions a commercially available ceramic tool has an even flank wear of 0.15 mm (0.006 inch) in 10 minutes -

- 23-0 09 838/1937

4234-G

and owned a commercially available tool made of TiC-Mo-Ki 0.28 mm (0.011 inch) wear. A commercial tool made from WC-Co failed at this high speed practically immediately.

The tool is also used to cut extremely hard 4340 steel (54 R) at 120 surface ^{meters per minute (400 S1 (1} M), 0.1J mm per revolution (0.005 ipr) and 1.3 mm (0.050 inch) depth, and a tool life of 15 minutes was found Under the same conditions, a commercial ceramic tool gave a tool life of 5 minutes, and a commercial tool made of TiC-Mo-Ni failed instantly.

B e J ₁ s ρ ie 1 2

The procedure of Example 1 is repeated except that the ingredients were used in the following amounts: 66.3 S alumina powder, 34.2 g titanium carbide powder and 8.18 grams of nickel aluminide. These amounts correspond to a mass that is 70% by volume of aluminum oxide, 25% by volume of titanium carbide and Contains 5% by volume nickel aluminide.

One made from this hot-pressed mass as in Example 1 Cutting point is exceptional, powerful as a cutting point for cutting out mead by turning and milling.

For example, the tip is used as a cutting tool for gray cast iron grade 30 (170 BHN) in a high speed rotary test at 375 surface feet per minute (1350 surface feet per minute) using one feeder of 0.13 mm (0.005 inch) per revolution and a cutting depth 1.3 mm (0.50 inch) is used. After a period of operation

- 24 009838/1937

of 10 minutes the tip shows even franc wear of 0.20 mm (0.008 inch) and a local flank groove of 0.3 mm. (0.012 inch).

The tip is also called a single tooth in a milling cutter 10 cm (4 inch) diameter used to make rods from gray, cast iron 30 (170 BIHT) 5 cm (2 inches) wide a surface speed of 4-7Om per minute (1575 feet per minute) and a feed speed of 0.25 mm (0.010 inch) per tooth with a cutting depth of 6.35 mm (0.250 inch) face mill on the center point.

The milling process is continued under these conditions for a bar length of 560 cm (220 inches) without wear. After examination, the cutting tip shows only a Uniform flank wear of 0.30 mm and a local one Flank wear of 0.91 mm (0.036 inch) with no cratering on the surface of the tool and no chipping or chipping of the edge occurred. Among the same Cutting conditions break off commercial, ceramic cutting inserts immediately.

B e is -pi e 1 5

The 'process of Example 1 is repeated except that the following ingredients are used: 71.6 g alumina powder, titanium carbide powder and 37.0 g · 14, β g.Molybdänaluminid (Mo ₇ Al) powder "talk These amounts ent a mass which contains 70% by volume of aluminum oxide, 25% by volume of u-jitancatfbid and 5% by volume of molybdenum aluminide.

A cutting point made from this hot-pressed mass according to Example 1 shows exceptional performance as a cutting point for cutting. Metal by turning and milling,.

009838/1137

For example, the tip is used as a cutting tool for gray cast iron grade $ 0 (70 BiIN) in a high speed rotating test at 375 surface meters per minute (1250 surface feet per minute) using a feed of 0.13 mm (0.005 inch) per revolution and a cutting depth of 1.3 mm (0.50 inch) is used. After an operating time of 10 minutes, the tip shows even flank wear as small as 0.05 mm (0.002 inch).

The same point is also used as a single tooth in a 10 cm (4 inch) diameter cutter to cut ^ 34-O steel (R. 36) bars 5 cm (2 inches) wide at a surface speed of 160 m each Minute (535 feet per minute) and a feed rate of 0.135 ¹ ^ ¹¹ (0.0053 inch) per tooth with a depth of cut of 2 mm (0.100 inch) on the center point dry.

The milling process is continued under these conditions for a rod length of 91> 4 · era without wear. Upon inspection, the cutting tip exhibited uniform flank wear of only 0.07 ram (0.003 inch) and localized plank wear of 0.15 ™ i (0.006 inch) with no pitting on the surface of the tool and no chipping or chipping of the edge. Under the same cutting conditions, commercially available ceramic cutting tools failed by splintering between 5 and 28 cm (2 and 11 inches) after a cutting operation.

Examples 4-7

The following examples are prepared using the starting materials and procedure described in Example 1, fallo not otherwise stated. The in the following Examples differing from titanium carbide and nickel

- 26 ¹ 009838/1937

42J4-G '

The raw materials used in aluminid are identified as follows: -

1) Alumina - Alcoa Superground Alumina XA-16 ,, will characterized by X-ray examination as α-alumina and "has a specific surface

rich of 13 m / g. ■. "

Having, industrial materials, a fine powder, which is characterized by X-ray investigation as pure zirconium carbide and a particle size of less than 1 la, measured with an ice-cher Unt he si eb _r classifier - 2) zirconium carbide. The specific surface area of the PuI

vers "is 0.5 m / g, and the oxygen content is" only 0.18 %.

3) Tantalum Carbide - Adamas Carbide Co., a fine tantalum carbide powder made by. X-ray examination is characterized as pure tantalum carbide and has a particle size of 5%, measured with a Fisclier lower sieve classifier. The specific surface area of the. Powder is 0.58 m ² / g, and the oxygen content is "at only 0.0?%. Electron microphotographs of a dry sample of this powder show luminescence with a diameter between 0.4 and M to 6 p., but mostly from about 2 to 3 yes. ·

4 ·) Titanium nitride - materials for industry, a titanium nitride powder with a part size corresponding to a sieve passage through a sieve of 44- μ. Sieve opening (minus 325 mesh), which is marked as pure titanium nitride on the basis of X-ray examination. The specific surface area of the powder is 1.1 m / g, the oxygen content is 0.8? % and the total carbon content is 0.33 %. Chemical analysis shows that the titanium content of the powder is 76.19 "^". ■

- 27 -009838/193 7

4234-G

5) Tantalum aluminide - a fine powder corresponding to the size of a core sieving through a sieve with sieve openings of 44 Ii (minus 325 mesh), whereby the product by X-ray en investigation was characterized as pure TaAl.

6) iron aluminide - a fine powder of a grain size corresponding to a passage through a sieve having sieve openings of 44 η (minus 325 mesh), the X-ray of _r on the basis of ray investigations, it was identified as pure Peal.

7) Nickel titanide - a fine powder corresponding to a grain size a sieve passage through a sieve with sieve openings of 44 / U (minus 325 mesh), which due to X-ray en investigations was marked as pure Ni, Ti.

The grinding conditions designated in the table with A, B and C correspond to the general conditions of Example 1 with the following requirements:

A) 4000 g of cobalt-bonded tungsten carbide inserts are used in a T, 3 liter steel roller or mill 375 ml of "Soltrol" oil was used.

B) 14,000 g of cobalt-bound tungsten carbide inserts are placed in a .38 liter (one gallon) steel mill or -Roller with 814 ml of "Soltrol" oil used.

C) 6000 g of cobalt-bonded tungsten carbide inserts are placed in a 1.3 liter steel mill with 375 nil "Soltrol" oil used.

The pressing cycle given in the table corresponds to the general ones Conditions of Example 1 with the exception of the temperature at which the sample and the mold are introduced into the hot zone the maximum temperature to which the sample is heated and the holding time at the maximum temperature. The-

- 28 00983 871937

these three variables are given in the table for each example / '^^ /

The metal cutting tests in the table correspond to the general conditions of the cutting tests in example i
the following additional features: high-speed rotation of 10A ^ T carbon steel .AISI (Brinell hardness ^ -183)} the speed "is 270 surface meters per minute (900 SFM); the feed is 0.15 mm (0.005 inch) ^ e revolution (IPR), the cutting depth of 1 _N, 2 mm (0.050 inch)

(iaKej
and there is negative scraping even and

Local flank wear is measured after 10 minutes of dry turning.

- "ν ί ν '

001838/193 7 ■. obiqinal inspected

Tabel

at ι Yol.% Al ₀ O, Palvermass e inter Hahlbe— • Manufacture and production - Max. Hold _t 3 Cross— 'S p 8.4 High Lei - very very N> G 2 3 metalli metalli thing- Varm press cycle temp. Time fracture- Metal cutting test J-, (120) dingy stungs Well Well O cal phase cal phase gene ° C b.Max. sturdiness Type of (T.R., K-DSi) turning capability Carbon / ^ game temp. temp. 1000 kg / cm Testing v. gray, S bcLQJ.
(50 + E _c ) No. o _c min. 6th (140) 9.8 cast High 30th 25 NiAl B. 1600 4th (140) iron very schv / indig- Well Vol.% 131 45 TiC 162 ""> Turning of Well turning G 24.4 244 30.2 1500 • hardened of coals 4th Weight% 4-5.5 fabric steel 4th 10.5 High Vol. * (150) dizzy G 50 10 Ni _x Ti A. 1400 turning O
ο Weight% 59.7 40 ZrC 23.35- - of gray, (P - 36.4 80.2 14.6 1000 cast OO
£ .% 5 - 49.0 iron U
OO Vol.% 60 10 TaAl, A. 1800 / 19th G 95 10 TaC 42 ⁵ Gev.% 52.5 43.7 23.2 1500 -J 6th 24.2 25th 10 CoAl C. 1700 29.8 65 TiN 18.05 19.5 105 11.8 1175 7th 68.6

CD CO CD

Claims (1)

λ. 20USI69S & ν- " ■ '-' 3Ä ^{S #} ^ ** ¹ ^ ⁷⁰ B a ten t a ns ρ rue he Dense, highly heat-resistant mass, characterized in that it consists essentially of:. (1) 20 "to 80t vol. % Aluminum oxide, (2) 10 to 7% by volume of a metallic compound Titanium carbide, titanium nitride, zirconium carbide, zirconium nitride, Mo "carbide, job nitride, tantalum pearlide, Tantalum nitride or mixtures thereof, (.5) 2 Ms JO% by volume of an intermetallic compound made of iron aluminide, iron titanide, gofeal aluminide, CpTsalttitanid, Hiekelaluminid, Uickeitit, anid ,. Tungsten aluminide, molybdenum aluminide, MpjOaluminide, Tantalum aluminide, titanium aluminide, zirconium aluminide or mixtures thereof "exists, whereby the mass has the further limitations that '.'" - "■ -". ■ (A) the average grain size less than 10 yes (B) the mass of two mutually interpenetrating three-dimensional network structures: where · one network structure consists essentially of • aluminum oxide and the other network structure essentially consists of the metallic; and the intermetallic compound exists and. ·. (C) the volume percentage of the metallic compound may not be less than the volume percentage the intermetallic compound. 2. Highly heat-resistant mass according to claim 1, characterized in that the volume percentage of aluminum oxide ^ ziwtschen $ 0 to 70 is. -. "■ 009838/1 Ö3t ι-η ORIGINAL INSPECTED 20Ü9696 J. Highly heat-resistant mass according to claim 2, characterized in that that the volume percentage of aluminum oxide is between 40 and 60. 4 ·. Highly heat-resistant mass according to Claim 1, characterized that the volume percentage of the metallic Connection is between 15 and 4-5. 5. Highly heat-resistant mass according to claim 4, characterized in that that the volume percentage of the metallic compound is between 20 and 40. 6. Highly heat-resistant mass according to claim 1, characterized in that the metallic compound consists of
Titanium nitride, titanium carbide, zirconium nitride and / or zirconium carbide. 7 · Highly heat-resistant compound according to claim 1, characterized that the volume percentage of the intermetallic Connection is between 3 and 25. 8. Highly heat-resistant compound according to claim 7 »characterized in that that the volume percentage of the intermetallic compound is between 4 and 20. 9. Highly heat-resistant mass according to claim 1, characterized in that that the intermetallic compound of iron aluminide, cobalt aluminide and / or nickel aluminide consists. ■ 10. Highly heat-resistant composition according to claim 1, characterized in that that the mean grain size is less than 5 yes. amounts to. 009838/1937 «54-0. ■ 11. Dense, highly heat-resistant mass, characterized in that it consists essentially of: ■ (1) 40 to * 60% by volume aluminum oxide, (2) 20 to 40% by volume of a metallic compound Titanium nitride, titanium carbide, zirconium nitride and / or zirconium carbide and (5) 4 to 20% by volume of an intermetallic compound made of iron aluminide, cobalt aluminide and / or nickel aluminide exists, the composition having the further limitation that: (A) the mean grain size is less than 5 M » ^{αη (} 1 (B) the mass is made up of two mutually penetrating three-dimensional network structures with one network structure consisting essentially of aluminum oxide and the other network structure consisting essentially of consists of the metallic and the intermetallic compound. 12. 'Process for the production of a tight, pore-free, highly heat-resistant mass, which is made up of two mutually penetrating net structures, one of which consists essentially of alumina and the other of which is essentially metallic and consists of an intermetallic compound, characterized in that: (1) 20 to 80% by volume of aluminum oxide, (2) 10 to 78 vol% of a metallic compound Titanium carbide, titanium nitride, zirconium carbide, zirconium nitride, niobium carbide, niobium nitride, tantalum carbide, Tantalum nitride or mixtures thereof and (3) 2 to 50% by volume of an intermetallic compound made of iron aluminide., Ice entitanide, cobalt alurainide, cobalt titanide, nickel aluminide, nickel titanide, - 33 - ■ '009838 / T937 20Ü9696 G Oh VoIf ramaluminide ,. Molybdenum aluminide, Ni ob al umini d, Q? Antalaluminiά, titanium aluminide, zirconium aluminide or mixtures thereof, but with the percentage by volume the metallic compound must not be less than the volume percentage of the intermetallic compound, are ground together until the ingredients are homogeneously mixed and the mean particle size is less than 10 ai that it is heated without the application of pressure so that volatile impurities can escape and then under pressure. Sintering is heated. -.34 - 009838/19 37