DE2057208A1 - Material for jewelry - Google Patents

Description

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,,. E. I. DU PONT DE NEMORS AND COMPANY 10th and Market Streets, Wilmington, Delaware I9898, V.St.A,

Material for jewelry

The invention relates to materials for jewelery, the 10 to 90 vol.% Refractory oxides, 10 to 90 Vol. Jf from hit ze.bee tändige η carbides, 0 to ΊΟ Vol.% Of auxiliary oxides and 0 to 10 volume .? made of metal. .

Some similar "materials, which have good hardness and strength, are described in US patent applications Serial Nos. 737 223 and 737 1 * 12 dated June 14, 1968. It has now been found that the materials according to the invention, if eie be formed into jewelery, have unusually advantageous properties heat resistant been Carbide sind'bereits used to make before watch cases, as in the United States. ^ -? described Patent Document 3 2 ^ 2 66H However heat resistant "!. Carbide have to.. Making jewelry have some disadvantages.

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limited resistance to corrosion by acids, such as is caused, for example by welding, and a ■ very high density, so that are produced from them ■ ^{s r <v} jewelery quite heavy. It has now been found that decisive advantages are achieved if oxides are added to the 'memory substances for such jewelry. The presence of oxides, such as aluminum oxide, reduces the electrical conductivity, increases the acid corrosion resistance and decreases the density, so that the jewelry made from such materials withstand the corrosion caused by welding and are specifically light. The oxides also give the jewelry a distinct and unusual color that looks quite pleasing. Furthermore, the products according to the invention are unusually scratch-resistant. They can therefore be worn for a long time without getting scratched or tarnishing. The products according to the invention are also very strong and tough and therefore very durable compared to many natural and artificial stones and stones Precious stones used for jewelry Finally, the products according to the invention are quite heat resistant and therefore do not melt or decompose at the temperatures at which conventional metals or alloys break down and diamonds are destroyed.

The invention relates to jewelry made of a hard, polished mass, 10 to 90 percent by volume of aluminum oxide, Zirconium oxide uride / or magnesium aluminate, 10 to 90 * Volume percent made from a carbide of titanium, zirconium, niobium, tantalum, tungsten, molybdenum and / or hafnium, up to 0 to 10 volume percent made of chromium, molybdenum, tungsten, iron, cobalt, "nickel, Titanium, zirconium, niobium, tantalum and / or hafnium and from 0 to. 10 percent by volume of silicon dioxide, titanium dioxide, magnesium oxide and / or a rare earth metal oxide, a porosity less than 5 #, a mean grain size of less than

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Less than 10 μ, resistance to sweat-related Corrosion and a density of less than 9 g / cnr.

Such jewelry is scratch-resistant, strong, tough and very durable ' adhesive and have a pronounced color *.

The products according to the invention consist of dense, fine-grained pesticides, aluminum oxide and zirconium oxide and / or magnesium aluminate in amounts of 10 to 90 percent by volume and optionally silicon dioxide, titanium dioxide, magnesium oxide and / or oxides of rare earth metals in amounts of 0 to 10 percent by volume, also carbides of titanium, zirconium, Niobium, tantalum, tungsten, molybdenum and / or hafnium in quantities from 10 to 90 percent by volume and chromium, molybdenum, tungsten, iron, cobalt, nickel, titanium, zirconium, niobium, tantalum and / or Contains hafnium in amounts from 0 to 10 percent by volume. These pests are characterized by a low porosity, a small average grain size, a polished surface, which is resistant to acid corrosion as it is by. human sweat and a density of less than 9 g / cm.

The products according to the invention are dense pesticides, which essentially consist of the heat-resistant oxides AlpO. ,, ZrO ₂ or Al ₂ O * .MgO and optionally SiO ₂ , TiO ₂ , MgO or oxides of the rare earth metals, furthermore from carbides of Ti, Zr, Nb, Ta, W ₁ Mo or Hf and optionally metallic Cr, Mo, W, Pe, Co, Ni, Ti, Zr, Nb, Ta and / or Hf.

a) oxides . '·

The heat-resistant oxides which can be used in the present invention are aluminum oxide, zirconium oxide and magnesium aluminate (Al ₂ O-, · MgO). These oxides are used in amounts of 10 to 90 volum per sent. Since with increasing content of oxides, the corrosion resistance and the electrical resistance decrease.

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men, the specific gravity is decreasing and the unusual Color is deepened, the preferred amounts of these oxides are 25 to 75 percent by volume in more preferred wines 40 to 75 percent by volume, in particular 50 to 75 percent by volume. In addition, other oxides, namely silicon dioxide, Titanium dioxide, magnesium oxide or the oxides of the rare earth metals, used in amounts up to 10 percent by volume will.

The mean particle size of the oxides should generally be below about 5 μ, and is preferably below about 2 μ. The preferred oxide is aluminum oxide, and the particle size thereof is preferably less than 2μ, in particular less than 0.5μ.

If the particles of the oxides used as starting material are much larger than 5 μ, they can be pre-ground to to shred them to an acceptable size. When all the components are mixed together, as is done, In order to achieve a high degree of homogeneity, there is of course also a certain degree of comminution of the constituents. .

The oxides suitable for the purposes of the invention can be in any desired form, provided they are only finely divided. k are. For example, the aluminum oxide can be in the form of γ-, y ^ - or cc-aluminum oxide or mixtures thereof. CC-aluminum oxide is preferred because it has a lower specific surface area than γ- or ^ -alumina and generally also contains less adsorbed water.

The oxides can be prepared by known methods or im Trade are related. A suitable commercial alumina is "Alcoa Superground Alumina XA-16" with a specific Surface area of about 13, m / g. Suitable commercial Before forms of other oxides are particle size powders available under 34μ from Metals for Industry Inc.

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b) carbides .

The carbides that can be used in the materials of the invention are the carbides of titanium, tungsten, molybdenum, tantalum,. Zirconium, hafnium and niobium. These carbides can be found in the Materials according to the invention in amounts of 10 to 90 percent by volume be used. Preferred amounts of these ingredients range from 25 to 75 percent by volume, in greater amounts preferably in the range from 19 to 57 percent by volume, in particular in the range from 19 to 47 percent by volume. Preferably the carbides of titanium, zirconium or tantalum are used, and titanium carbide is particularly preferred.

The carbides suitable for the purposes of the invention should have an average particle size of less than 5 μm and preferably voii are less than 2μ. If that raw material Has particle sizes of significantly more than 5 μ, it can be pre-ground to the particle size to 5 μ or v / eni-. ger to belittle. When all components are married together For the purpose of achieving a high degree of homogeneity, as already mentioned above, there is also a certain amount of comminution, instead of.

Suitable carbides can be produced using known processes or obtained commercially. Suitable · commercial carbides are di · powder old grain sizes below 44 μ, those of the Material for Industry Inc. or Cerao Inc., Butler, V / i a c ons in, V.St.A.

α) metals ''. , "

The metals that can be used in the materials according to the invention are molybdenum, tungsten, chromium, iron, nickel, cobalt, titanium, zirconium, niobium, tantalum, hafnium and mixtures thereof.

These ifetals are used in the materials according to the invention used in amounts from 0 to 10 percent by volume. Preferred amounts of metal lie in the range of 3 to 6 percent by volume, because

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an optimum of chipping resistance in this area when cutting or grinding the pieces, as well as ease of polishing and corrosion resistance.

Of the heat-resistant metals, molybdenum or tungsten or mixtures thereof with ferrous metals are preferred used. Of the ferrous metals, nickel is preferred. The joint use of molybdenum is particularly preferred or tungsten with nickel.

As already mentioned, the materials according to the invention have relatively high metal contents, namely up to 10 percent by volume of metal. An increase in the metal content should, however, with a corresponding increase in the carbide content Going hand in hand to maintain the corrosion resistance of the materials. It is believed that Molybdenum diffuses into the lattice of carbides such as titanium carbide, so there is little or no free metallic material Molybdenum remains more when there is enough carbide, which gives it high corrosion resistance remain.

The metals suitable for the purposes of the invention should mean part sizes of less than 5 μ and preferably of less than 2μ. If the starting powder is part of the it can be pre-ground to disintegrate the particles to 5 μ or less. smaller. When all components are ground together to achieve a high degree of homogeneity, of course also some crushing takes place.

Metal powder of the required grain size and the required Grade 3 are commercially available or can be prepared in known ways. A suitable manufacturing method is the reduction of the corresponding metal oxides with hydrogen at low temperatures or the reduction

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of iron, cobalt or nickel carbonate with hydrogen Temperatures of about 600 to 1200 ° C. Such manufacturing processes should be carried out at the lowest possible temperatures after the sintering and agglomeration of the metal. Opportunity to suppress.

In the production of molybdenum and tungsten from their oxides, it is best to be a two-stage reduction-to-use nerif because some of these oxides are relatively volatile. The first reduction stage is carried out below the melting point of the oxide, for example at 600 ° C. The second reduction stage then follows at, for example, 900 ° 0, at which point the reduction is completed.

The metals produced by the methods described above can be ground in an inert medium to their to enlarge the specific surface, and then they can be cleaned e.g. with hydrochloric acid. For grinding the metal Nearly preferably uses grinding media made from the same metal that is to be ground or from the components, that are to be mixed with the metal, or made of a very wear-resistant material to avoid any contamination introduce by abrasion of the grinding media.

Typical suitable and commercially available metals are fine tungsten powder from General Electric, Detroit, Michigan, U.S.A., with an oxygen content of 0.21, a nitrogen adsorption certain specific · surface by about 2 m / g and a Broadening of the X-ray diffraction lines determined crystallite size, of 174 ταμ as well as the fine nickel powder available from International Nickel Co. with an oxygen content of 0.09 5 ", a specific surface area determined by nitrogen adsorption

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of 0.5 m / g and one by widening the. X-ray diffraction lines determined crystallite size from 150 to 170 ταμ.

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d) impurities *

The materials used for the production of the Y / er materials according to the invention The ingredients used should preferably be very pure. It is particularly desirable to remove contaminants such as substance, which can have an adverse effect on the dense masses "

On the other hand, small amounts of many impurities that do not significantly impair the properties of the products are permitted. For example, the metal can contain small amounts of other metals; however, it should not contain any low-melting metals such as lead. Also ψ small amounts of other carbides may be present. Even oxygen can be permitted in small amounts, such as those contained in titanium carbide, in which a few percent of titanium oxycarbide have formed through the action of air. But once the powdery components have been ground together and are in an extremely reactive state, there is oxidation, especially

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of metals, easily held, and should be avoided.

The production of intimate mixtures of carbides and oxides as well as optionally metals in the form of a powder can according to U.S. Patent Application Serial No. 737 223 of June 14 Made in 1968.

The intimate powder mixtures of carbides and oxides and optionally Metal are processed into a dense solid material by sintering or hot peeling, as is mentioned in the above United States patent application Serial Ho. 737 223 is described.

The dense 'masses, consisting essentially of oxides, carbides and possibly metals, can be used without using preforms any other material into jewelry will; However, the dense masses can also be

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layer of metal, wood, plastic or textile attached or used as a setting for precious stones, semi-precious stones or minerals, The Schiauokv / aren thus obtained Can be for ornamental, utility, or both Serve purposes at the same time,

Jewelery are so well known and their sizes, sizes, combinations of components and uses are so varied that it is impossible and unnecessarily to enumerate all types of jewelery for which the masses according to the invention can be used. The following abbreviated list ₄ is only intended to give a few examples of suitable application purposes. Precious stones, shells or synthetic organic or inorganic substances, are used ». Combinations can be made, for example, by soldering, soldering, gluing, cementing, edging, dowelling and sewing. In this way you can make jewelry such as the following

Watch cases, hinge, hansehefctenknasten, tie pins, earrings, Collars, needles, buttons, clips, decorative hangers, open buttons, cigarette cases, bracelets, metal decorations, Monograms, trophies, medals,! Bottle openers, shoehorns, Hairpins, hair accessories, shoe buckles, belts, without all, Pillenschaohtoln »Powder compacts, clothes or skirt buttons ,. Talismans for bracelets, identification tags, Badge, paperweight »

Cutting method to prepare such jewelery, and um'die gemäsa dense masses of the invention to verformen- and polish the skilled person are known and described in detail in "aohiolgenden examples.

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The materials according to the invention are characterized by their resistance to corrosion against the action of sweat, their high mechanical strength, their external properties Toughness and hardness, low porosity, kloine grain size and homogeneity of the mutual mixing of the components.

The mechanical strength and hardness are determined according to the known method for determining the transverse fracture resistance and the Rockwell A hardness.

Methods for determining the porosity, the grain size and the homogeneous nature of solid substances are described in US Pat. No. 3,409,416. The masses according to the invention are characterized by a porosity of less than 5 »and a mean grain size of less than 10 μ. Preferably, the Maaeen according to the invention have a porosity of less than $ 1 and an average grain size of less than 2 μ,

The toughness is only qualitatively determined by looking at the finished product Drops the product from a height of 2.13 m freely onto a hard holafuos floor, the products part of the invention Do not break or split off,

The actual density of the masses according to the invention can be determined by known methods, the simplest, however a previously measured sample in air and under water weighs, The water should be boiled before the sample is weighed in order to drive off dissolved loiffc. Dia Dlohte calculated «I then from the> equation

Guwichb in the air χ spessifLochos weight

_η , _Λ,. · the water

Density = »- ■" - '- ■ - - ~~ -

Weight in air - weight in water

I) Theoretical Dlohto dor mass canoe on the basis of the deliberation can be calculated that the volume oinar given

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The weight of the mass is equal to the sum of the volumes of the constituents, which in turn is calculated _{from the weight of the individual constituents divided by their density f.} .

The solid bodies according to the invention have a density of less than 9 g / cm V and since their porosity is generally less than 1 $ , their actual density is usually higher than 99 $ of their theoretical density. ■ / '.

One of the characteristic properties that the fabrics on * should show so that they are suitable for pieces of jewelry that are worn in constant contact with the skin, such as rings, Bracelets and watch cases, is their corrosion resistance to the secretions of human skin. It is E.g. known 'that even watch cases are made of stainless steel when worn normally ** on the wrist in hot climates can corrode. In order to assess this property, a corrosion test is carried out in a liquid of the average composition of the human sweat. A solution is prepared, the composition of which is specified in the work "Normal Values in Clinical Medicine "by F. * W · Sunderman and F. Boerner (publisher. ■ W-.B. Saunders Co., Philadelphia and London, 1949) on page 488 the mean composition of the human Sohweiesee is equivalent to. The composition is as follows:

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WasseV ·, 99 _f 02 Sodium chloride • 0.7 Lactic acid 0.1 acetic acid 0 _f 0096 Propionic acid 0 _f 0062 Cacrylic acid and caproic acid 0 _f 0046 Citric acid. 0 _f 004 Ascorbic acid 0 _t 004

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Urea, or uric acid, as "traces" in the middle Composition deo human sweat anceben bind, were not added to the corrosion test.

The corrosion test solution is placed in a beaker at a constant bath temperature of 40.degree
stirrer gently touched.

Bath temperature of 40 ° C introduced and with the help of glass

The cuts used for the corrosion samples have a size of 20.57 mm 12.7 mm 2.54 mm. You will be like they are cut with resin-bonded diamond sonic gears without further grinding or polishing for the test P · used, with the exception of a possible adaptation of the cuts to the standard size.

The neat test samples are accurately weighed and measured and then immersed in boiling dimethylformamide for 4 minutes to obtain the To remove impurities from the surface. After taking it out from the dimethylformamide, the sections are washed with water and acetone, dried in a vacuum oven and immediately transferred to the corrosion solution.

In the measured time intervals samples are removed from the corrosion test fluid, rinsed with distilled water and with acetone _f in a vacuum oven dried and then weighed overall w. Then they will. cleaned again in boiling dimethylformamide, rinsed with water and acetone, dried and again introduced into the corrosion test liquid. The weight loss, unit of the surface area of the sample, is calculated for the given periods of time. The surfaces of some samples are examined by optical microphotography before the start of the teat and at certain time intervals during the test in order to observe the extent of the etching.

The dense Maasen Geinsees of the invention are characterized by a weight loss of less than 0.2 mg / cm naoh 10 days of immersion in the synthetic

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see "Black solution at 40 ° C. This corrosion resistance against welding is higher than that of stainless steel ITr. 304, a metal used in the manufacture of watch cases » is used, and much higher than that of cobalt-bound tungsten carbide, which is currently being divided is used by scratch-resistant watch housings.

The jewelry vegetables of the invention can be used for purely ornamental purposes or at the same time for practical uses and ornamental purposes. These jewelry materials have an unusually pleasing metallic sheen, which is due to the presence of the 'oxides somewhat soft and' less glaring than that of conventional polished metals or of polished tungsten carbide. Although the unusual appearance is due to the presence of the oxide phase, the difference can be seen in appearance, like ¹ with most aesthetically pleasing effects, can be observed with the human eye, but difficult to define or measure quantitatively. In contrast to conventional metals such as stainless steel, silver or gold, those made from the materials according to Invention of existing jewelry is unusually scratch-resistant. As a result of their fine grain and their lack of porosity, the materials can be polished to an unusually high degree, and even if treated roughly with conventional building materials or clothing, the surface becomes polished, including metal, glass, concrete, bricks, wood, plastics, etc. ., not scratched or dull. In view of their good corrosion resistance, the jewelry according to the invention does not tarnish if they are worn for a long time in contact with human skin and with sweat. The maneuvers according to the invention are stronger and tougher than many materials, such as natural or artificial stones or gemstones or jewel mountings, and therefore they are more durable. Since the substances according to the invention are externally heat-resistant, oils suffer: at high temperatures, at which conventional ones

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Metals or alloys break down and diawanes disintegrated be, icein melting and no decomposition. This unusual Combination of shapes makes the fabrics amazing valuable for use in jewelry.

In the following examples, parts and percentages, unless otherwise stated, relate to the weight,

example 1

The composition of the substance in this example is 50 percent by volume Made of aluminum oxide, 45 percent by volume made of titanium carbide and molybdenum and nickel share up to 5 percent by volume from the same space.

The aluminum oxide is a very finely divided aluminum oxide ("Alcoa Superground Alumina XA-16") and is identified by X-ray diffraction analysis as pure -aluminium oxide with a specific surface of 13 m / g. This specific Surface corresponds to spherical particles with a groose from 115 πιμ. Serve appears under the electron microscope a-Alumlnluraoxldpulver in the form of aggregates of aluminum oxide crystals with diameters from 100 to 150 ΐημ.

Dao titanium carbide powder has a nominal mean tellchengrüsoe of 0.6 μ, determined with the PiBher-Unteriebgröcoön-Klaasler device, and one determined by nitrogen adsorption specific surface area of 10 m / g. This "ground to 0.6 μ" Titanium carbide powder is on the market from Adamas Carbide Corp., Kennllworth, New Jersey, V.St.A. A picture of the dry powder taken with an electron microscope shows that the titanium carbide particles Dürchmes boron zv / inches 0.2 and 3 μ and sometimes in the form of lookeron aggregates sticking together. The titanium content is 77.0 y », the total carbon content 18.8 #, the content of free carbon about 0.07 #, and the Saueretoffanalyetn.

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result in oxygen levels between about 0.0 and 1.6 #. The analysis by emission spectroscopy shows that titanium is the main component and that the material also contains 0.5 to 2 # Mo, - O ₁ 5 to 2 # W ₁ 0 ', 5 to 2 ^ Ki, 500 to 2500 ppm Al, 200 up to 1000 ppm Co, 300 to 1500 ppm Pe, 300 to 1500 ppm Kb, 200 to 1000 ppm Cr, 200 to 100 Ω ppm Si, 100 to 500 ppm Zr, 50 to 250 ppm Ca, 50 to 250 ppm Mn and 5 bio contains 25 'ppM Mg «

The molybdenum powder has the conventional normal properties and is available from Sylvania Electric Products, Inc., Philadelphia, Pa., V.St.A. It has grain sizes of less than 44 μ, one determined by nitrogen adsorption specific surface of 0.29 m / g and a mean crystallite size determined by broadening the X-ray diffraction lines from 354 ιημ. One with the electron microscope The recorded image shows that the molybdenum powder consists of grains 1/2 to 3 μ in diameter, which are in the form of open Aggregates sticking together. The chemical analysis of the Powder gives 0.2 # oxygen and no other impurities in amounts of more than 500 ppm *

The kickel powder is conventional grade and is available from International Nickel Co., New York City, IT.Y., V.St.A. The nickel fine powder comprises 0.15 i "carbon · 'fabrics, 0.07 f' oxygen and less than 300 ppm iron. The specific surface area of the nickel powder is 0.48 μm / g, and the X-ray diffraction diagram shows only nickel, which, due to the broadening of the X-ray diffraction lines, has a criotallite size of 150 μm. Under the electron microscope, the powder appears to consist of polycrystalline grains with a diameter of 1 bio 5 μ.

The powders are ground by adding a 1.3 liter Steel roller mill of 15 cm diameter with 6000 parts yorbo traded, cylindrical grinding media also bound with cobalt

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denem tungsten carbide 6.35 mm long and 6.35 mm in diameter and with 28.7 parts of saturated paraffinic carbon (Boiling range 165 to 210 ° C, .. "SoItrol 130") charged. To the Mill packing becomes 83 "6 parts" aluminum oxide, 47.0 parts Titanium carbide powder, 7 »65 parts molybdenum powder and 6.68 parts Nickel powder added. . .

The mill is then closed and rotated at 90 rpm for 5 days calmly. After opening the mill, the contents are discharged, but the grinding media remain in the mill - * - ben. D'ie mill is using the paraffinic hydrocarbons given above rinsed until all the ground pests are out are worn.

The ground powder is transferred to a Yäkuun evaporator and the excess hydrocarbons are poured off after the suspended material has settled. The wet cake that remains is dried in vacuo with the action of heat ¹ until the temperature of the evaporator is between 200 and 300 ° 0, the pressure being less than 0.1 mm Hg. The powder is then just turned off. Final handled by air.

The dry powder is passed through a sieve using nitrogen 0.21 mm mesh size poured and then in sealed plastic container !! repealed under nitrogen.

A compacted ingot is made from the powder by using the powder in a cylindrical graphite shape a cylindrical cavity with a diameter of 25.4 mm, the exactly matching ones facing each other. Kolbpn is hot-pressed. ' A J piston v / lrd in one End of the mold cavity held stationary, with 17.5 parts of powder poured into the cavity under nitrogen and evenly distributed by turning the mold and tapping lightly on one side. Then the top piston is below

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Hand pressure applied in place. The compound The porm and its contents are then placed in the vacuum chamber brought in a vacuum hot press »the press in a vertical position Position held, and the up and down herauara-. lowering pistons are placed between the two opposite graphite pistons of the press under a pressure of 7 to 14 kg / cs » compressed. Within a minute the shape will be in the lifted up the hot zone of the furnace, which is at 1000 ° C. det, and the furnace temperature is increased immediately, whereby the both plungers are locked in their positions so that no further movement takes place during the heating-up period can. The temperature is increased from 1000 to 1800 ° 0 within 10 minutes and held at 1800 ° C for a further 2 minutes an even heating of the. Ensure sample. A pressure of 280 kg / oa is then applied over the flasks for 4 minutes brought to action. Immediately after the pre-pressing the form with its content, still between each other opposite plunger, taken out of the oven into a cool zone, where it burns to a dark red glow within 5 minutes catches. · · '

The fora and its contents are then removed from the vacuum oven and the ingot taken out of the mold and with the ' Sandblasting device frees yon adhering carbon.

The density of the Iertigerziugniaset> determined by accurate weighing and determining the dimensions, is 4.82 g / cm.

The hot-pressed mass shows itself on microscopic examination at 1000-fold magnification as essentially non-porous. This property is important because non-porous substances are more corrosion-resistant than porous substances of the same chemical composition. Structurally, the mass consists of, an extremely fine, coherent network of sioh interpenetrating polycrystalline alumina and metal bonded titanium carbide.

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The sample is so tough that it won't break or splinter if you let it fall freely onto a hardwood floor from a height of 2.13 m.

The man has a specific electrical resistance of 2000 hikrοohm cm. This level of conductivity indicates indicate that the conductive components of the structure, namely the metal and the titanium carbide, were present in a coherent form. Images made with the electron microscope " show a very fine-grain structure, with a few grains having sizes of more than 1 or 2 μ. The aluminum oxide is generally the worst phase.

The coherent nature of the alumina phase can be shown if the titanium carbide and the metal are removed from the mass by anodic attack for 24 hours Dissolves aramonium bifluoride solution. One remains behind - Elektriaoh non-conductive porous Schidht on the surface ·, ■ which appears unchanged to the unarmed JLugs, but under the electron microscope proves to be porous because the electrically conductive components have been removed.

The sample is polished by pressing its surface firmly against rotating cloth disks soaked with diamond dust. A Buehler polishing machine is used for this. One ) Diamond sole grinding disc Kr. 400 with one rotational speed of 1175 rpm, is used in the first stage of the polishing process and a diamond grinding wheel Kr. 1000 with a rotational speed of 550 rpm, in the second and last Yerfah'ren level of polishing used.

The polished sample so aufgekittete has a pleasing looked a Darkerj Io _r turbid silver color, and metallic luster and is used as a metallic tiepin

* The ohemiohe analysis shows aluminum oxide, titanium carbide, molybdenum and nickel also about 2 % iron, which is probably

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borrowed by abrasion introduced from the mill * 4- Ϋ » Y / olfrom in the form of tungsten carbide and 0.5 ί * cobalt, both of which were probably introduced by abrasion from the bald bodies.

The bar, which has a diameter of 25 »4 ram and a thickness of 7.62 mm, is cut to size so that a square piece of 12.7 sides is now removed from its base. From this center piece, samples of 20.3 ώη χ 12.7 mm 2.54 mm are cut for the corrosion test. 20.3 mm thick ¹ strips are cut from the remaining material on each side of the cut-out center piece and further cut into square rods 17.8 mm 17.8 mmi for testing for transverse breaking strength. Other parts of the billet are used to determine the indentation hardness and for other marking of the product. The transverse resistance, determined by bending the test rods measuring 1.78 mm 1.78 min, over a bending length of 14.3 mm, is 105.5 kg / mm ² . The Rockwell A hardness is 94.0.

Using, cuts of 20.57 mm 12.7 mm x 2.54 mm, corrosion tests are carried out in a liquid of. of the composition of human sweat a at 40 ° 0. The composition of the human Sohweisaee is described in your work "Normal Values in Clinical Medioine ¹¹ By FW Sunderman and F. Boerner (Verlag WB Saunders & Co, Philadelphia and London, 1949), on page 488 as follows:.."

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Weight-5 * Waseer 99.02 Sodium chloride • 0.7 Lactic acid 0.1 acetic acid 0.0096 Propionic acid 0.0062 Caprylic acid and caproic acid 0.0046 Citric acid 0.004, Ascorbic acid 0.004

A liquid of this composition is produced, and the precisely measured and weighed and boron-containing cleaned corrosion test pieces are placed in the liquid immersed. The test pieces are cleaned by immersion in boiling dimethylformamide for 5 minutes and subsequent rinsing with water and acetone.

The test is carried out by looking at the samples for a specific Time in the corrosion test liquid, ' then take out, wash with water and acetone, in the vacuum oven dries and weighs. After weighing, the samples are cleaned in boiling dimethylformamide, with water and acetone rinsed and, when dry, returned to the corrosion test bath. This procedure is used for various Time spans repeated.

The corrosion test liquid is used during the investigation ochwaoh stirred, and their temperature is in a thermostatic bath held at 40 ° 0. Specimens of engineering grade 304 stainless steel and cemented carbide (tungsten carbide-cemented carbide "Oarboloy" 90) of the same size will be in the same Way cleaned and examined for comparison purposes.

After 10 days, the mean weight loss of the sample prepared according to the above example is 0.14 carbon black / cm . Under the same conditions, the hard metal shows an average

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Weight loss of 25 mg / cm and the stainless steel lir. 304 (a metal similar to that used in the manufacture of watch cases is used) a mean weight loss of 0 * 5 feet / cm.

The experiments show that the mass according to the invention against

the action of human sweat more corrosion resistant

as stainless steel No. 304 and "significantly corrosion-resistant

ger than commercially available tungsten carbide hard metal.

Examination of the tungsten carbide sample under the optical Microscope at 740x magnification after 10 hours long tr Exposure to the corrosive liquid under the conditions described above shows that the surface is largely etched is. The mass according to this example, on the other hand, shows after 10 hours of exposure to the corrosive liquid under the optical microscope, only slight etching the surface. ·

¹ example 2

This example explains the manufacture of a watch case from the Maea · described in Example 1.

According to Example 1, a dry, sun Eeiaapreasen is suitable " tea powder made.

A watch case is made from this powder by the powder is hot pressed in a graphite mold that is so is built so that the powder becomes a hang when hot pressing can be deformed with a round hole which is so big is that the encapsulated movement of a wrist watch can later be inserted into the Hing by press fit, whereby the Ring serves as a protective and decorative housing. The graphite mold consists of a 10.16 cm long hollow cylinder made of graphite with an outside diameter of 6.35 cm, and the cross-section of the Hohlraun · hai the shape of a square with rounded sides *

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The maximum inside width of the cylinder is 5 »08 cm. In the lower end of the cylindrical shape is a hollow piston with an outer diameter so beroeooen iot that the piston fits exactly into the shape of the inside diameter of the mold. The piston has a cylindrical cavity of round cross-section with a diameter of 4.13 cm. Dao The end of the piston in the mold is beveled or shaped like a key formed so that the bottom of the au3 the powder forming ring does not have a flat surface, but a pleasing rounded surface. A third hollow cylinder with an outer diameter of 4.13 cm and a wall thickness of 1.59 mm fits exactly into the hollow piston and. protrudes beyond the piston into the mold. A massive one The rod fits into the thin-walled inner cylinder in such a way that it prevents it from collapsing during the pressing process. A weighed amount of powder, - which is calculated so that it is a completely tightly compressed stuolc of the correct Thickness is poured into the mold and by tapping the mold in that of the inner wall of the mold ', the outer one Surface of the thin-walled, cylindrical spacer and the upper hollowed end of the bottom piston formed cavity sagging. Then a second hollow piston is inserted into the unit from above, which forms the upper surface of the powder cavity. The whole

The aggregate is heated under the conditions of Example 1. The pressure is brought from above and below by means of massive graphite pressure pistons which act on the ends of the hollow pistons protruding from the top and bottom of the mold. After the end of the Preos process, the hair dryer is removed from the hot zone and the solid rod serving as a spacer is allowed to slide out of the center of the unit. When the shape cools down, the pressed watch case ring pulls stronger than the graphite. If one would leave the solid rod in place, the ring would be as a result of decision

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breaking tensions. Instead of desoen the presses shrinking ring the thin-walled ring remaining in the hole Graphite cylinder together, and the cylinder, but not the Hing, bursts. The thin-walled cylinder only has the task of to facilitate the initial pulling out of the solid rod, otherwise it would be held by sticking it to the hanging. When the mold has cooled down, the Piston and ring, if necessary, removed by pressure. The ring is then polished according to Example 1, whereupon you use an encapsulated clockwork.

Example 3

This example explains the use of a hatred according to Example 1 as an attachment for tie clips.

According to example 1, a dense, hot-pressed bar is produced manufactured.

The bar is cut to size so that its hit fee a 14.3 mm x 4.76 mm rectangular piece removed will. The rectangular piece is impregnated by pressing its surfaces against rotating, ait diamond deaf Polished glass washers. For this process, the in example 1 specified machine of Buehler, Ltd. used. A Diamond grinding wheel Kr. 400 with a speed of 1175 rpm, is used for the first step of the polishing process and a No. 1000 diamond grinding wheel at a peripheral speed of 550 rpm, for the »long, final stage of the process used for foiling.

The reohteok-shaped piece polished in this way looks like. metallic Silver aue and is used as an ornamental attachment by it is cemented to the surface of a metal tie clip with epoxy resin.

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The Schniucketüok this Beiopiels shows an excellent Resistance to corrosion caused by soh white.

Example 4

You work on. Example 1, but with a powder composition made of 40 percent by volume aluminum oxide and 60 percent by volume Titanium carbide.

The steel mill with a capacity of 1.3 l accordingly has 47.7 parts Alumina and 88.9 parts of titanium carbide bosohickt.

Following the procedure of Example 1, with the difference an ingot is produced that the maximum temperature for hot pressing is 1850 ° C. The product has a density of. 4 »85 g / cm, a« Hookwell Α hardness of more than 94.5 and a Transverse strength of 84.4 kg / mm. You can turn the ingot off dropping it onto a hardwood floor to a height of 2.13 m, without breaking or splintering.

When examined under the microscope at 1000 times magnification tion of the ingot is essentially non-porous. The structure consists of two very fine, connected and one another penetrating nets made of polycrystalline cs-AlunsiniuB-oxide or made of titanium carbide.

The mass has a specific electrical resistance of 1000 microohm.cm, which means that the titanium carbide the coherent, electrically conductive component of the structure is.

Images made with the electron microscope show a very fine-grained power; few grains have a size of nthr as 3 or 4 μ

The polished sample has a very pleasing appearance! the material is cloudy or smoky, dark, silver-gray and has a » tall shine.

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The chemical analysis shows that, apart from aluminum oxide and titanium carbide, there is also 0.5 ⁰ A iron, probably coming from the abrasion of the Stohlmühle, 1.1 5 Y / olfram, presumably in the form of tungsten carbide, and 0.1% Cobalt are present, the latter two substances probably having entered the mass through abrasion of the grinding media.

Corrosion tests in a liquid with the mean composition of human sweat at 40 C. Show that this sample is more corrosion resistant than stainless steel No. 304 and far more corrosion resistant than tungsten carbide hard metal ("Oarboloy 90 ^H ).

The bar from this composition is made according to Example 3 Cut to size and polished to obtain a square piece with a side length of 12.7 mm. The square piece, is used as a decorative attachment by covering it with epoxy resin a medallion is cemented on.

Example 5

You work according to example 1, J β do oh nit a powdery sauce * Settlement of 25 percent by volume aluminum oxide, 25 percent by volume Zirconium oxide, 45 volume percent titanium carbide and 5 volume percent Metal, which in turn consists of 50 percent by volume nickel and 50 percent by volume molybdenum.

The zirconia powder is commercially available under the name "Zircoa AHC" .available. This powder has a medium one Particle sizes of 1.3 μ, determined with the Fisher Unteraiebgrössen-Xlassler device, and a specific surface of 1 m / g, determined by nitrogen adsorption. The chemical analysis of this zirconia oxide shows a calcium oxide content of 0.1 j6.

The 1.3 liter steel mill is filled with 29.83 parts of aluminum oxide, 42 parts of zirconium oxide, 66.6 parts of titanium carbide, '■

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7.64 parts molybdenum and 6.63 parts nickel beochickt.

A watch case produced from this mass according to Example 2 has an attractive, cloudy, dark, silver-gray appearance and can be dropped freely onto a hardwood floor from a height of 2.13 m without breaking or to splinter. The density of this watch case is practically equal to the theoretical density.

The corrosion test shows that this watch case is more resistant to the effects of human corrosion than stainless steel No. 304 and Wolfrano carbide hard metal ("Carboloy 90 ^H ).

B e i β ρ ie 1 6

The procedure is as in Example 1, but with a powder mixture of 40 percent by volume aluminum oxide, 10 percent by volume titanium dioxide, 45 percent by volume titanium carbide and 5 percent by volume of a metal mixture, i.e. 50 percent by weight Niokel and also 50 percent tungsten.

The titanium dioxide powder let from Materials for Industry, Inc. receives and has a duroh nitrogen ad- * sorption certain apezifisoha surface of 8.3 m / g. Sine Photo taken under the electron microscope shows that the powder consists of aggregates, which in turn consist of fine particles of about 1/4 μ Durohmesser are composed.

The 1.3 liter steel mill is filled with 53.3 parts of aluminum oxide, 6.4 parts of titanium oxide, 66.6 parts of titanium carbide, 7.65 parts of molybdenum and 6.67 parts of nickel.

An example of this powder mixture through Heiaapreesen 1 bar produced has a Rockwell A-IIarte of 95 »5 and • A cross-working activity of 98.4 kg / mm. The ingot is poor

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tough and can be dropped from a height of 2.13 m on a hardwood floor without breaking or chipping.

Under the microscope at a magnification of 1000x it merges the ingot as essentially non-porous; its density is. equal to his theoretical view. Images made under the electron microscope show a very fine grain structure, with a few grains having sizes greater than 1 or 2 μ.

After foiling this sample has a pleasing appearance · The sample has a smoky or tarnish _f dark '' silver gray · color. A hexagonal piece is cut from the sample, which is inserted into a flatin ring as an ornament. "

The so produced «SohnuokstUek shows an · excellent ·. Corrosion resistance to the action of neneehllohen Schwelse.

Example 7

• You work according to Example 1, but using a powder mixture of 60 percent by volume aluminum oxide »35 percent by volume zirconium * carbide and 5 percent by volume metal» consisting of JiO percent by weight of nickel and 50 percent by weight of molybdenum,

The zirconium carbide powder is from Materials for Industry » Inc. and has a specific surface area determined by nitrogen adsorption of 0.5 a / g and an oxygen content of 0.18 jC. '

The 1.3 1 steel grinder is filled with 71.6 ropes of aluminum oxide, 70.5 parts of zirconium carbide, 7/65 ropes of molybdenum and 6.66 parts of nickel charged. .

A bar produced from this mass according to Example 1 has a diameter of 4.7 g / approx, an Eockwell A hardness of 9311

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a transverse breaking strength of 87 _r 9 kg / mm.

Bel iooO-faohtr-enlargement shows the bar an estimated one Porosity of veniger -as 1 f ·. Hit the electron microscope Recorded images show a very fine core structure; Few of the grains are larger than 5 μ.

By cutting with a diamond wheel bonded with resin and foiling, two pieces of jewelry with a pleasing »cloudy, dark» egg-gray appearance are made from the ingot, These two pieces are cemented onto two cufflinks with epoxy resin. They show pieces of jewelry that have been preserved in this way an excellent resistance to the corrosion caused by human sohwei ··.

¹ Example B

The procedure is as in Example 1, but with a powder mixture made of 50 yoluaprosent aluminum oxide, 45 volume percent TjLtancarbid, 4 volume percent niobium and 1 volume percent nickel.

The niobium (from Dar Cerao, Inc.) is in the form of a powder with grain sizes of less than 44 μ. This powder has a specific surface area of 0.2 / g determined by nitrogen adsorption, and images made with the electron microscope show that it consists of dense particles of 2 up to 12 μ in diameter, with most of the particles Intersections between 4 and θ μ have

Bit 1.3 1 holding steel mill is charged with 58.5 parts of aluminum oxide, 66.5 parts of titanium carbide, 10.28 parts of niobium and 2.66 parts of nickel.

A bar produced from the powder mixture according to Example 1 has a density of 5 * 02 g / om, a Rockwell A hardness of

94.0 and one transverse breaking strength of 109 kg / m » ² .

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The bar shows an excellent ability to resist the corrosion caused by human sweat.

The ingot is bound by cutting with a resin bond Diamond wheel and foiling to a piece of jewelry from Processed with a pleasing silver-like appearance. The piece of jewelery is attached to a steel belt buckle with epoxy resin puttied up.

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Claims (8)

Claims 1. Material for jewelry made of a hard polished mass, characterized in that the mass consists of 10 to 90 vol. # Of aluminum oxide, zirconium oxide and / or magnesium aluminate, 10 to 90 vol.% Of a carbide of titanium, zirconium, niobium, Hafnium, tantalum, tungsten and / or molybdenum, from 0 to 10 vol. consists of silicon dioxide, titanium dioxide, magnesium oxide and / or oxides of the rare earth metals and has a porosity of less than 5% _3, an average grain size of less than 10 u, resistance to corrosion caused by sweat and a density of less than 9 g / cnr . 2. Material according to claim 1, characterized in that the mass consists of 25 to 75% by volume of aluminum oxide, zirconium oxide and / or magnesium aluminate, and 25 to 75% by volume of a carbide of titanium, zirconium, hafnium, tantalum, niobium, Tungsten and / or molybdenum and 3 to 6 vol. $ Of chromium, molybdenum, tungsten, iron, cobalt, nickel, titanium, zirconium, niobium, tantalum and / or hafnium. 3. Material according to claim 1, characterized in that the mass has a porosity of less than 1 % and an average grain size of less than 2 μ. 109823/2026 BATHROOM OBlGUNAL 4. Material according to claim 1, characterized in that the mass of 40 to 75 Vol.Ji of aluminum oxide, to 19 up to 57 vol. made of titanium carbide, zirconium carbide and / or tantalum carbide and 3 to 6% by volume *? made of molybdenum, tungsten and / or mixtures of these metals with iron, cobalt, or nickel. 5. Material according to claim 4, characterized in that the carbide titanium carbide and the metal a mixture of 10 up to 95 wt. Molybdenum and 5 to 90 wt. Nickel is. 6. Material according to claim 4, characterized in that the mass is 50 to 75 vol.? made of aluminum oxide, 19 to 47 vol.? made of carbide and 3 to 6 vol.? made of metal. 7. Material according to claim 6, characterized in that the carbide and the metal are a mixture of titanium carbide 10 to 95 wt. Molybdenum and 5 to 90 wt. Nickel is. 8. Use of a material according to claims 1 to 7 for watch cases. 10982372026