DE2646738A1 - OBJECT COVERED WITH A REFIR-PROOF METAL - Google Patents

Description

MÜLLER-BORE DEUEBL SCHÖN H E RTE L

PATE NTAWVViLTE

DR. WOLFGANG MÜULER-BORE (PATENT ACQUISITION FROM 1927-197S) DR. PAUU DEUFEl-. DIPU.-CHEM. DR. ALFRED SCHÖN. DIPL.-CHEM. WERNER HERTEU. DIPL.-PHYS.

S / W 36-1

WARNER-LONDON, INC, Greensboro, North Carolina,

United States

Object covered with a refractory metal

The invention relates to protective coatings. In particular, it deals with discontinuous coatings of refractory metal particles, such as abrasion-resistant, heat-resistant, chemical-resistant or similar materials that are based on Surfaces have been applied that are made of metals, metal alloys and metal-containing substrates or the like exist.

The invention is explained in more detail by the accompanying drawing. This shows in a schematic representation various possible structural properties of the part near the surface of the backing metal.

The invention is based on the knowledge that any document of a metal, a metal alloy or a

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HUSCUEiI 80 -SIEBERTSTR. 4 · POSTEACn 860720-ICABEIiIMTrEBOPAT-TjEI .. (089) 474003 · TJElEX 3-24385

Metal-containing material can be provided with an application of a refractory or protective metal with a melting point of at least 1490 ⁰ C if such a base is brought into contact with an electrolyte which is at least partially between the refractory metal particles and the surface of the base material.

Of the refractory or protective metals that can be used, the following may be in powder or particulate form Metals and all alloys that contain these metals are mentioned: boron, chromium, cobalt, iridium, molybdenum, Niobium, osmium, palladium, platinum, rhenium, rhodium, ruthenium, tantalum, thorium, titanium, tungsten, vanadium, yttrium, zirconium.

The initial shape of these metal particles can be idiomorphic, block-like, equiaxed, spherical, acicular or dendritic. The size of these particles is preferably as small as possible and is usually between 0.01 and about 1 mm (microraeter). The underlay materials on which the refractory Materials that can be applied can be made of aluminum, iron, chromium, cobalt, nickel, copper, magnesium, tin, Titanium or an alloy of these metals, for example steel, cast iron, brass, bronze, solder, etc. It can also be any other suitable base metal.

To the deposition of the particulate refractory metal on the portion near the surface To carry out the support, it is also necessary that a finely divided electrolyte material is present that at least is partially present between the particulate refractory metal and the backing metal.

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Of the electrolytes that have been found to be suitable, acids may be mentioned, such as the mineral acids, hydrochloric acid, Nitric acid, sulfuric acid, phosphoric acid, perchloric acid, fluorosilicic acid, etc., as well as the acid anhydrides, such as Arsenic trioxide and chromium trioxide etc., as well as the organic acids, Tartaric acid, malonic acid or the like. Suitable basic electrolytes are alkali and alkaline earth hydroxides, such as sodium, potassium, Lithium, calcium, magnesium hydroxide, etc. Also suitable as electrolytes are: alkali and alkaline earth salts of the above specified acids, such as the alkali metal halide salts, in particular the chlorides, chlorates, fluorides, nitrates, sulfates, phosphates, Carbonates etc., as well as metal salts, this being part of the electrolyte The metal used may be any of the metals mentioned above as refractory metal or backing metal was, and such a metal can form any salts, for example sulfates, phosphates, nitrates, carbonates, Chromates, molybdenates, tungstates, etc.

Other chemical compounds are also suitable as electrolytes, such as ammonium thiocyanate, potassium thiocyanate, zinc sulfate, Ammonium carbonate, ammonium sulfate, potassium sulfate, sodium sulfite, Sodium carbonate, potassium cyanide, calcium nitrate, potassium chloride and calcium chloride.

The electrolyte can generally be any acid, base, or salt. He must be in the presence of Dissociate moisture, i.e. it must be able to conduct electrical current, and to a sufficient extent or a sufficient percentage of dissociation is required. More precisely, the electrolyte must be sufficient have a high equivalent conductance.

The conductance is the ratio between the equivalent conductance at a dilution of 1 g equivalent per IUl of water and the

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Equivalent conductance at an infinite dilution, where the
The temperature is 25 ^° C. (cf. “The Physical Chemistry of Electrolytic Solutions”, Harned and Owen, Rheinhold Publishing Corp., 1958). The electrolytes suitable according to the invention are those with conductivities between approximately 0.13 and 0.93 and preferably above
0.60.

In the following some acids, bases and salts as well as the corresponding approximate equivalent conductance values are given, which the
Requirements of the invention meet:

Acids O, 90 Hydrochloric acid 92 nitric acid 60 sulfuric acid

Bases

Sodium hydroxide 0.88

Potassium hydroxide 0.93

Kaiζ ium hydroxide 0.80

Strontium hydroxide 0.86

Barium hydroxide 0.86

Salts

Silver nitrate potassium chloride sodium chloride potassium bromide Natr iumn itrat Sodium acetate potassium chlorate calcium chloride

0.86 sodium carbonate 0.61

0.86 ammonium sulfate 0.59

0.82 barium nitrate 0.57

0.92 strontium nitrate x 0.62

0.82 lead nitrate 0.54

0.79 cupric acetate 0.33

0.83 zinc sulfate 0.38

0.75 copper sulfate 0.38

As dissociation is a criterion for choosing an electrolyte to carry out the process according to the invention increases with an increasing dissociation capacity of the electrolyte

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Ability to cause the inventive reaction. Man It can be assumed that the more complete the ionization of an electrolyte, the more effective it is for the purposes according to the invention serves.

As far as the method according to the invention is concerned, there is no need Electric current can be applied to introduce the refractory or protective material into or on the surfaces to apply the surfaces. However, since it is assumed that the process is in principle electrolytic in nature, this affects Applying an electric current the process and promotes it. However, an applied current is required to carry out the process not necessary, since the internally generated electrolytic currents are of sufficient magnitude on a microscopic scale possess in order to achieve the results according to the invention.

To achieve the electrochemical reaction to deposit the refractory metal on the backing material, find how to assumes an intimate interaction between the refractory metal present in the form of individual particles, the electrolyte and the documentation material. In the case of solid electrolytes, it has been found that the exact total particle size of the electrolyte and the refractory metal is not critical or important, since this size mainly depends on the dimensions of the usual harder refractory metal. The electrolyte particle size is preferably such that fine particles in one Ranges from 10 micrometers to about 1 mm, with the particles preferably being 10 to 100 times smaller than the associated refractory metal particle at the time of application to the backing metal.

To initiate the reaction, assuming that some of the backing metal has been exchanged for the refractory metal it is important to partially ionize the refractory metal,

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to start the exchange reaction with the backing metal set. The ion concentration has been found to be between 1 and 60,000 mg of the refractory metal ion per liter of the solution should be. Preferably the range should be between 1000 and 15,000 mg of the refractory metal ion per liter of the solution.

It is believed that the refractory metal ion after there has been an exchange reaction entered with the backing metal forms a location for the refractory metal particle to be deposited will. These reactions are believed to only take place on a microscopic scale. To refractory metal ions too produce, at least in sufficient quantity to set the desired reactions in motion, it is important to that the refractory metal apply a nascent surface on at least a portion of the surface of the refractory Has metal particle. For reasons that have not yet been fully understood, this fresh surface allows for the refractory Metal in combination with the electrolyte and the moisture present, the required concentration in a sufficient time to generate on refractory metal ions. All refractory metals are in the traditional sense of the word in the insoluble in the presence of moisture, but sufficient ion concentrations, as required according to the invention, from the nascent surfaces of the refractory particles .in the presence of the electrolyte and sufficient moisture. The required nascent surface passes through easily produce any mechanical effect, for example by rubbing, grinding or other mixing, an abrasive effect or by a chemical action of the electrolyte or some other reactive material that is a nascent or growing one Surface generated on the refractory metal particle.

The extent of the mechanical or chemical effect used to generate it

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- ^η

the nasal surface is not critical because of any Mixing a certain nascent surface is created. The refractory metal ions are removed from the nascent surface generated in a period of about 1 minute to 30 days, and preferably 1 to 20 hours. The time depends on the humidity, temperature and solubility of the refractory metal. Time is therefore not critical. It is only It is important that there is the required concentration of refractory metal ions and that there is a certain nascent surface is generated with the particulate refractory metal in the portion near the Surface of the backing metal is deposited.

To the intimate relationship between the electrolyte and the refractory metal present in the form of individual particles generate and bring the electrolyte between the surface of the base metal and the refractory metal, as well as cause that to a large extent a nascent surface is exposed to the refractory metal particles are different Methods possible. If the refractory metal is in the physical state of dry powder under ambient conditions, and the electrolyte is also in a clear In dry granular form, an intimate blend can be made by thoroughly mixing the two powders. The amount range of the refractory metal is between 99 and 50 and preferably between 96 and 66% by weight, based on the dry mixture of refractory metal and electrolyte. The electrolyte can be 1 to 50 and preferably 4 to 34 weight make up the dry mixture of refractory metal and electrolytes.

It has been found that to increase the electrochemical effect According to the present invention, an element or a compound used as an agent for preventing an electrochemical

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Polarization is used, optionally with the refractory metal in the form of individual particles and the electrolyte in an amount of 1 to 10% by weight, based on the total mixture of refractory metal and electrolyte, can be introduced. Examples of such depolarizing compounds or elements are MnO ₂ / platinum metal powder, CuO, HgO, ionizable iron or tin salts, such as the halides, sulfates, nitrates, etc., as well as activated carbon.

The thickness of the electrolyte coating on the refractory particle should be as continuous and uniform as possible. she can vary from molecular films up to 25 micrometers or above up to 1 mm. Preferably a larger part should of the refractory metal surface, but a smaller portion of only about 10% is acceptable.

Mixing or trituration has been found to produce of one or two nascent surfaces on the refractory metal particle and coating the refractory Particle with an electrolyte powder can be carried out if both the electrolyte and the refractory metal powder are noticeably dry and have little or no noticeable moisture. This mixing usually takes about 30 minutes to 30 days. To generate the refractory metal ions, however, there must be sufficient moisture, otherwise no ions are formed.

Regardless of whether the refractory metal and / or the electrolyte are dry under ambient conditions, water should be in the mixture of refractory metal and electrolyte in one Amount of about 0.5 to 60% by weight, based on the total mixture, before the treatment of the backing metal with the mixture are present. Preferably the amount of moisture should be 1 to 40% by weight.

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It is also advisable to use an intimate, moist mixture of the electrolyte and the refractory metal in the form of a paste or slurry or solution in a liquid medium such as water form.

A sufficient amount of water can then be present in the mixture when the electrolyte exhibits an electrical resistance of less than about 10 ohm-cm. If the electrolyte is liquid, then the addition of a liquid medium may be unnecessary, but is preferable, especially in the case of strong mineral acids.

The presence of some water in the refractory metal and electrolyte mixture is responsible for creating the concentration of ions of the protective metal as well as important in terms of the reactivity of the electrolyte with a certain probability an ion exchange with the underlay metal.

This simple blending step or the combined blending and mixing Aging stage, if carried out over a period of 10 minutes to 30 days, can replace the time that is required to generate the nascent surfaces and the concentration of refractory metal ions, although then if the refractory metal ion concentration is insufficient, remixing and / or further aging may be required for a period between 1 and 30 days. The actual concentration of the refractory metal ions is the test for the need to adhere to a further mixing or aging period.

The intimately mixed powders, pastes, liquids, etc. of the electrolyte with the refractory metal can then by spraying, dipping, brushing, tumbling, spraying, or any other distribution method or stratification method using

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generation of the mixture of refractory metal and electrolyte a thin coating can be applied to the base material.

A manufactured mixture of the refractory metal with nascent Surfaces and the electrolyte with the required moisture content and the necessary concentration of refractory Metal ions can be in a drum with the to be treated Parts are swirled. Furthermore, the use of a ball milling device is possible without balls being used to to effect a sufficient coating of both the refractory metal and the electrolyte and thus the next according to the invention Execute stage, namely the deposition of the refractory metal. In the case of the wet mix, the Electrolyte is present between the surface of the backing metal and the refractory metal and acts in exactly the same way as in the case where the refractory metal particles have been coated with the electrolyte.

The temperature at which the refractory material replaces the backing metal can be ambient, but it can also be any suitable temperature. The temperature is not critical with regard to the mode of operation or the feasibility of the invention. It has the effect of increasing the rate of the reaction as the temperature rises. It has been found that a time of about 1 and 168 hours and preferably 6 and 72 hours at ambient temperature is sufficient to effect impregnation of the backing material with the refractory material or replacement of the backing material with the refractory metal. Longer times are not critical and do not adversely affect the process. Shorter times can be useful if there is an adequate response. The temperature range can be between 0 and 20Ö ° C and preferably between 10 and 100 ⁰ C and in particular

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between 15 and 4 0 ⁰ C lie. The lower limit of the temperature is not critical. It can be lower than 0 ^° C., but this requires a longer reaction time.

The areal density of the mixture of electrolytes and refractory metal as a protective material that is applied to the base metal is not critical and can range from about 0.5

2 refractory particles of protective coating / mm up to a completely even coating of the mixture on the surface of the backing metal vary, which is about 10 particles / mm at a particle size of 1.0 micrometer. Particles 1 to 5 microns in size can have a concentration

4 6 2

of these particles from about 4x10 to 10 particles / mm for have complete coverage. In the case of particles approximately -325 mesh (nominal maximum diameter 44 micrometers), which includes commercially available metal powder in combination with an electrolyte, can be the concentration of the to be applied to the substrate metal Particles vary from about 10 to 10 particles / mm. the The amount and size of the refractory metal particles applied does not determine the removal of the particles and the size of the discrete particles that are then actually applied to the base.

The product according to the invention is described in more detail below. The attached drawing shows schematically the various possible structures that can be found on the base metal as well as within the section near the surface 12, defined by the levels A-A, takes place.

The character of the discrete particles 14 of refractory metal, those in the section near the surface of the backing material to some extent depends on the practice of the invention. For example, fire

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solid metal particles in the section near the surface of the pad with essentially the same shape and nominally the same or slightly smaller size compared to the Particles in the powder or the single particle powder of the refractory metal used as the starting material for carrying out the method is used before. This characteristic of the invention was determined by microscopic examination both the refractory metal powder and the individual particulate material used to carry out the process, and the deposited refractory metal particles in the processed metal substrates. A multitude of such secluded ones Particle has dimensions of no more than about 2 micrometers. All such separated refractories Metal particles have been found to be between 0.01 and 100 micrometers in size.

Furthermore, in the section 12 near the surface of the Underlay metal 10 a certain amount of refractory metal particles 14 can be deposited, both larger and smaller Have dimensions as the nominal mean particle size of the refractory metal powder of the particulate material, that was used to carry out the procedure. Are, for example, the initial forms of the refractory metal particles, which are used to carry out the method according to the invention, idiomorphic or block-like and have an average dimension of 1 micrometer, the refractory metal particles deposited may have such a character and, in addition, both the shape of large spherical particles with a diameter of up to 10 micrometers and smaller ones abutting one another Have particles with an average dimension of less than 0.2 micrometers. The deposited refractories Metal particles 10 can take such additional forms, but it has been found that these deposited particles are from 0.01 micrometers to 100 micrometers in size, where a large number of the separated refractory particles

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has measurements less than about 2 micrometers.

The places where the discrete deposited refractory metal particles sit are preferably at the grain boundaries, the pores or valleys of a microscopic nature in the portion near and / or within the surface of the backing metal any irregularities in the section near the surface of the backing metal caused by previous physical or chemical effects may have been generated, for example, depressions 16 that are produced by machining etc. The distribution of refractory metal particles on substantially planar microscopic single phase surfaces of the backing metal is obviously spatially arbitrary. Similarly, it is believed that the appearance the microelectrolysis essentially in an arbitrary spatial manner on such planar parts of the substrate metal Formation of the initially discontinuous pattern of deposited discrete refractory metal particles occurs.

As the process according to the invention progresses, a plurality of these discrete refractory metal particles juxtaposed to form nests 18 from these particles deposited randomly on the substantially planar surfaces 20 of the backing metal. These particle nests are spaced from each other and are preferably due to irregularities in the zone near the Surface of the base metal, for example - recesses 16, which go back to processing, formed.

Since the inventive process reactions during further Steps are carried out, for example by increasing the treatment time or by increasing the treatment temperature or the like, the randomly arranged nests of discrete particles 14 adjoin nearby nests, whereby

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microscopic (small scale) zones 22 of deposited refractory metal in the zone near the surface of the Base metal are formed. Such microscopic zones of deposited refractory metal appear to be continuous to be, as the underlay metal is hidden within the zones. These microscopic zones 22 made of refractory metal are placed at a distance from each other in an arbitrary manner, but they are preferably attached to irregularities formed in the zone near the surface of the backing metal, e.g. due to processing Depressions 16 or the like.

Since the process steps according to the invention continue to be carried out and in particular the diversity of the reacting surfaces by increasing the surface density of the discrete particles As the substrate is increased, the mutual bonding processes of the refractory metal become more apparent. The preferably and randomly arranged microscopic zones 22 of refractory metal adjoin others in the vicinity microscopic zones made of refractory metal, for example as at point 24, where macroscopic (large-scale) Zones 26 of deposited refractory metal can be formed in the zone near the surface of the backing metal. Such macroscopic zones 26 of deposited refractory metal appear continuous to the naked eye because they are within such zones the base metal is covered. These macroscopic zones of deposited refractory metal are in spaced apart and obviously arbitrary in the zone near the surface of the backing material arranged.

Subsequently, with continuous lateral growth of the refractory metal due to the method described above all of the backing metal 10 with the refractory metal

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covered and shielded by this (see. Reference number 28). Further the refractory metal builds itself up in a direction perpendicular to the surface of the substrate so that the refractory metal layer at the point 30 is thickened. In this way it becomes cohesive and obviously continuous Layer 32 of refractory metal is created which is bonded to the backing metal 10 and is an integral part with this forms.

Such a distribution and subsequent connection of the deposited discrete refractory metal particles in the manner described above gives a deposition pattern that from any other metal deposition process, including in particular electrochemical processes, is different. For example, a metal sheet made of mild steel according to the invention treated, then the naked eye sees a continuous coating that bends 140 ° around a radius of 3 mm (3/8 inch) can withstand without any visible cracks or tearing even at an enlargement of three diameters This coating, although appearing continuous, has a discontinuous structure.

The treatment of a tool steel base according to the invention The method involves the application of discrete refractory metal particles in the form of randomly arranged particle nests. These particle nests are deposited in the zone near the surface of the backing metal, preferably on the substantially planar metal matrix exposed between the carbide particles of this steel. Treatment of a Steel of the type SAE 1018 according to the method according to the invention gives a similar but more complex pattern of refractory metal particle deposition in the zone near the Surface of the pad. In this case, the refractory metal particles are discretely arranged in the form of randomly arranged partial

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nests on the substantially planar ferrite micro-component deposited on the substrate and additionally preferably on the intermediate carbide ferrite part of the pearlite micro-component of the backing metal distributed. In the case of both types of steel, the continuous metal phase is the preferred location for a separation of refractory metal particles. In both cases one observes arbitrarily attached at a distance Nests of discrete particles resting on substantially planar portions of the continuous metal matrix phase of the substrate are deposited.

The built-up thickness of the deposited particles that form an adhesive coating can vary according to time, temperature as well the ion concentrations fluctuate. Also one during a certain period of time, during which the electrolyte or the Refractory metal is in contact with the backing material, applied current can affect the coating properties. A thickness starting with molecular films, which can be selectively continuous or discontinuous, and up to 0.5 mm can be deposited in the zone near the surface of the backing material. It's on it to point out that one of the unique features of the invention is that the refractory metal is applied to the backing material is applied and part of the same replaced so that no change in the dimension of the backing metal can be determined by conventional measurement methods. Only in the most advanced state of deposition can a noticeable Dimensional changes can be determined.

According to a particular embodiment of the invention, in microscopic amounts of at least one corrosion product 24 are present in the zone near the surface of the backing metal. These corrosion products are the solid chemical compounds which are essentially insoluble in the electrolyte. which are formed as a result of any corrosion reaction

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be, in which the base metal chemically through the In a variety of cases, these compounds consist essentially of cations from the electrolyte Backing metal and anions from the electrolyte. The corrosion products can be used as underlay metal hydroxides, chlorides, nitrates, sulfates, cyanates, carbonates, acetates or the like occur, it can also be more complex base metal compounds act, such as oxyhydrates, oxychlorides, thiocyanates or the like.

If corrosion products are present, then they tend to nucleate and grow in the zone 12 near the surface of the substrate 10 and in the places accessible to the electrolyte, especially in places where the refractory metal is not in direct physical contact Is in contact with the document. The essentially lateral growth of the corrosion products tends to at least partially surround the deposited refractory material in the form of particles 14 _f nests 18, microscopic zones 22 and macroscopic zones 26 (cf. reference number 36) (cf. . The reference number 38), is partially embedded (see. The reference number 39) or is included (see. The reference number 40). Since these corrosion products adhere to the substrate metal, it is believed that they cause the refractory metal particles to adhere more firmly to the substrate, particularly when surrounding or enveloping the refractory metal particles.

The composite structure formed in this way consists of refractory metal particles that adhere to the backing metal are connected, refractory metal particles that are surrounded or enclosed by corrosion products or by corrosion products Adhere even more firmly to the substrate, and in addition some refractory metal single-particle material that is completely covered by Corrosion product is coated. Such a composite structure increases the likelihood that certain refractory metal parts

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surfaces, especially those that are completely encased by corrosion product, mechanically embedded in the base metal, welded into the base metal by friction are, in the vicinity of the surface zone, as a natural result of forces generated when that coated part is put into operation. In this sense, the composite coating or composite coating acts as a reservoir, that of a continued supply of refractory metal singular material in the zone near the surface of the backing metal adheres, guaranteed. In some cases the corrosion product itself acts as a depressant lubricant from friction and / or wear either by its own properties or as a porous reservoir for conventional lubricants, such as oils, fats, graphite, molybdenum disulfide or the like.

The preferred final stage in the treatment according to the invention Underlay metals must be washed quickly with hot water and then dried quickly in the air. By this measure, the microelectrolytic effect is ended, with practically all ionized products and salts from removed near the underlay metal substrate. The draining washing liquid, usually water, contains valuable undeposited refractory metal particles, their recovery and use in the implementation of subsequent measures according to the invention is appropriate. To 99% of the total weight of the refractory metal particles can be recovered by standard means, for example by decanting, sedimentation, centrifugation or the like, if these measures are applied to the draining wash water however, particles of not all refractory metals are recoverable in this way.

There are specific combinations of refractory metals and electrolytes that, unfortunately, are linked to each other

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Connect washing cycle. This connection is therefore undesirable since the product thus formed is essentially unusable for recycling purposes and not readily can be converted into particles again. In such cases it has been found that mineral acid treatments of the wash water can be used, the concentration of the acid in the wash water between 1 and 10% by volume, based on the total amount, held to avoid the bonding or cementing process. For example, it was found that in the event a treatment mixture of tungsten metal powder as the refractory metal and calcium chloride as the electrolyte, the cementation thereby Avoid having hydrochloric acid in an amount of about 5% by volume, based on the total wash water running off, is added, whereupon the drain is washed again and decant or centrifuge to recover the tungsten powder that is not consumed in the treatment reaction has been. The concentration of hydrochloric acid required for Adjustment of an appropriate wash water concentration is used is not critical.

The following examples illustrate the invention. example 1

To use tungsten metal as an abrasion resistant refractory material in to apply the zone near the surface of high carbon steel textile machine lift rings Tungsten powder used in pure form, but the purity is not particularly critical. This powder has a size -325 mesh (particles that pass through a sieve with a mesh size of 0.045 mm). From this it follows that the tungsten metal particles have a maximum dimension of 45 micrometers, with many of the particles being much smaller than that size, down to about 1 micrometer maximum dimension. This dry tungsten powder is made with

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dry anhydrous calcium chloride powder with a commercially available particle size in a ratio of 1 part by weight of CaCl2 to 10 parts by weight of tungsten powder. These two powders are then mixed or ground together for a period of about 24 hours in a shaking ball mill, using porcelain balls in a porcelain jar 6 to 12 mm in size. The use of a mortar and pestle during the same period of time is also satisfactory. During this co-milling, nascent surfaces are believed to be formed on the refractory tungsten particles. The particle size of the CaCl is reduced, the CaCl ₂ being applied or smeared onto the surfaces of the tungsten metal powder particles.

The co-milled mixture of dry powders is then allowed to stand in contact with moist air with a relative humidity of 60% for about 20 hours. Due to the hygroscopic nature of CaCl ₂ , water is absorbed by this mixture in an amount corresponding to approximately 10 to 20% of the total weight of the moistened mixture. At this point, most of the CaCl _{2 has} dissociated into ions, while a small amount of the tungsten metal powder has also gone into solution in ionic form, producing an equivalent concentration of about 3000 to 10000 mg of the refractory metal ions per liter of the liquid phase of the mixture is. The moistened and aged mixture is then applied as a slurry to the take-up rings in such a way that the rings are tumbled together with the mixture. The parts are previously cleaned in a CCl bath to remove grease, oil or other foreign matter, in order to expose the zone near the surface of the steel backing material of the rings for the action of the mixture of electrolyte and refractory metal and to allow contact. During a period of 24 hours at room temperature, the refractory metal powder particles, as well as the refractory metal ions, together with

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the electrolyte and the steel base act, a deposition of metallic tungsten particles in the zone near the surface of the steel base of the rings. The final stage of processing the steel hauling rings described above is rapid washing with hot (80 to 100 ^° C.) water and then rapid drying in the air. This ends the microelectrolytic effect. In addition, ionized products and salts are removed from the vicinity of the steel substrate.

The product obtained is a steel part, in the zone of which, near its surface, tungsten metal in the form of arbitrary arranged nests of discrete particles is deposited. This spatially discontinuous deposition of tungsten particles is permeated with a solid corrosion product which is believed to be essentially hydrated Iron (III) oxides act as adjoining masses in of the zone in the vicinity of the surface of the steel base are deposited and adhere to this. This corrosion product surrounds, envelops and partially overlaps the deposited tungsten particles, forming an adhesive composite corrosion product layer is formed on the steel base.

The coated steel surfaces give themselves to the unarmed Eye recognizable as evenly coated and darkened, showing a macroscopic green color and preferably visible electromagnetic radiation in a wavelength range between 580 and 610 nanometers compared to a adsorb uncoated support. Such a quality of treated surfaces results in both increased adsorption as well as an increased emission of electromagnetic radiation, the latter of particular importance with regard to the Dissipation of radiant heat is.

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Example 2

In order to apply tungsten as an abrasion-resistant refractory metal to the surfaces of heat-treated bevel gears made of low-alloy steel, the wetted and aged mixture of tungsten and CaCl _{2 is produced} exactly as in Example 1. This mixture is then applied in the form of a slurry by brushing onto the wear surfaces of the bevel gears in such a way that a surface density of approximately 10 refractory metal particles per mm ^{2 of} the surface of the cleaned steel bevel gears is set. Within 24 hours at room temperature, the refractory metal ions work together with the electrolyte and the low-alloy steel backing material to produce a coating of metallic tungsten particles in the zone near the surface of the steel bevel gears. The wheels are then washed and dried as in Example 1.

Laboratory sliding abrasion tests of similarly treated plates made of low carbon steel (type SAE 1018) show that with a load of 0.5 kg and a speed of 120 cm / sec. the treated material is about 250 times more resistant to abrasion is a similar untreated sample as measured by weight loss. That used to perform these accelerated 1 hour abrasion tests treated material has the same macroscopic appearance as the treated bevel gears described above made of low-alloy steel.

Example 3

Tungsten powder is used to apply tungsten as an abrasion-resistant refractory material to the surfaces of parts a size of -325 mesh (particles passed through a sieve with a clear mesh size of 0.045 mm) is used. That

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dry wolf grain powder is mixed with dry anhydrous CaCl _{9 of} a commercially available particle size. The powders are mixed as in Example 1 and ground together.

The jointly ground mixture of the dry powders is then sprayed onto cleaned abrasive surfaces in such a way that an areal density of approximately 3 × 10 refractory metal particles per mm ^{2 of} the surfaces is established. Such abrasion surfaces are then subjected at 40 ⁰ C to the action of air with a relative humidity of 40 to 50% over a period of 20 hours. Within this 20 hour period, the refractory metal powder particles and the refractory metal ions act together with the electrolyte and the wear surfaces to produce a deposit of metallic tungsten particles in the zone near the surface of these wear pieces.

Example 4

To apply tungsten as an abrasion-resistant refractory metal to the surfaces of parts, a wetted and aged mixture of tungsten and calcium chloride is made exactly as in example Ύ / / . A relatively large amount of this mixture is then placed in a stainless steel vessel, which acts as the positive pole of an electrolytic cell. In this case, the wetted mixture serves as the "electrolyte" of the electrolytic cell. With the polarities indicated, a DC voltage of approximately 1 volt is applied across the cell (stainless steel - "electrolyte" - substrate to be coated). In this way, the electric current is allowed to flow for a period of about 6 hours, after which it is found that the substrate has assumed the typical blue tone that also occurs in the case of the surfaces produced according to Examples 1 and 3, in these cases no current has been applied. In

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- JMT-

In this case the application of the current accelerates the deposition of the discrete particles.

Example 5

Variously designed and shaped loop thread guides and needles made of hardened carbon steel as well as some loop thread guides and needles made of chrome steel and tufting knives made of a tungsten steel are exposed to the action of a mixture of 1.5 ecm of hydrochloric acid and 20 g of powdered tungsten (-325 mesh (parts that pass through a sieve with a clear mesh size of 0.045 mm)) exposed. The hydrochloric acid forms the electrolyte and is mixed in an amount of 1 part of the acid with 5 parts of water. The mixture of hydrochloric acid and tungsten is rubbed into a uniform mixture over a period of 24 hours before contacting the parts to be treated. After trituration, the mixture is in the form of a moist powder. The moisture content is adjusted to 9% by weight, based on the total mixture. After a 24 hour aging period, the tungsten ion concentration should be at least 500 mg per liter of solution. The desired product is then applied in an amount of 200 parts per mm ² evenly at 25 ° C. to the surfaces of the loop thread guides, the tufting knives and the needles. These items are left in open troughs for a period of 12 hours. At the end of this period, all pieces will have a slightly darker appearance. After the end of the reaction period, the pieces have surfaces with an abrasion resistance that lasts longer than that of untreated pieces.

The definitions of three used according to the invention are given below Terms specified. Undefined terms are to be understood in their usual meaning:

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Deposition: includes chemical, mechanical or physical Connection of one material to another and particularly relates to covering, binding, adhering and embedding.

Refractory metal ion concentration: this is the concentration of refractory metal ions in an aqueous solution, on a weight basis, assuming the metal ionized even in a monovalent or polyvalent state is. This simple concept of ionization cannot represent the actual case. For example, tungsten can be used in solution Wolfrair.ation occur, whereby tungsten initiates intimately with oxygen is.

Zone close to the surface: The underlay metal and its immediate surroundings are considered to be the system in question. In parallel to the actual boundary between the base metal and the environment, two surfaces are assumed, and one on each side of the actual boundary that is far enough from that boundary that any irregularities and inhomogeneities of the surface of the backing metal completely fall between them. The volume that is from these two Enclosing surfaces is the "area near the surface" of the backing metal. This definition corresponds that of J. Willard Gibbs (see C.E. Reid "Principles of Chemical Thermodynamics", Reinhold Publishing Company, New York, 1960). As for the structural details, the zone near the surface depends on the measures taken to produce it the surface are applied, but in general all such surfaces have characteristic openings, cracks or pores of irregular size or shape as follows: wide or lateral dimensions between 0.02 micrometers and mm and depth of approximately 0.02 micrometers to 200 micrometers, irregular distributed over the surface of the object to be treated. Essentially planar surfaces of the support material

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rials remain between these openings. The openings can
an undercut and thus an overhanging section of the
Have surface that extends into the openings of the backing material. All such geometric structural details are defined in the present case as falling into the zone in the vicinity of the surface.

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Empty ropes

Claims (30)

26-6738 claims 1. Article made of a base metal with a relatively low wear resistance, which is coated with a refractory metal, characterized by a base metal with a relatively low wear resistance, a zone near the surface of the base metal, a refractory metal with a melting point of at least 1490 ⁰ C, which is deposited in the zone near the surface and adheres to the substrate metal, the refractory metal being deposited in the form of discrete particles, a plurality of such particles which adjoin each other to form nests and the nests from the particles of the refractory metal are spaced apart to form an adherent wear-resistant coating on the backing metal. 2. Article according to claim 1, characterized in that the refractory metal a) consists of idiomorphic particles, being a plurality these particles have dimensions less than 2 micrometers, and b) equiaxed particles, being a plurality these particles have dimensions of less than 10 micrometers, or idiomorphic or acicular particles. 3. Article according to claim 1, characterized in that a solid corrosion product of the base metal in the zone in near the surface and adhered to the backing metal, the corrosion product at least partially surrounds other refractory particles in locations where these other particles will not adhere to the backing metal, thereby an additional abrasion-resistant coating from the other refractories Particle is formed. 4. The object of claim 1 or 3, characterized in that 8U9809 / 0610 ORIGINAL INSPECTED - -28 - that a plurality of the nests farther together to form a plurality of microscopic refractory metal sections adjacent, at least some of the sections being spaced from one another. 5. The article of claim 4, characterized in that the solid corrosion product of the backing metal is formed in the zone near the surface and on the backing metal adheres to places not occupied by the microscopic sections or the refractory particles with the corrosion product at least partially surrounding the microscopic sections and firmly surrounding other refractory Holds particles that are not firmly attached to the backing metal, thereby forming another abrasion-resistant coating is. 6. Object according to claim 1 or 3 or 5, characterized in that that a plurality of the nests adjoin one another to form miroscopic refractory metal sections and a multiplicity of such microscopic locations on one another to form macroscopic locations from the refractory metal border on the base metal, 7. The article of claim 1, 3, 4, 5 or 6, characterized in that that the zone near the surface of the base metal has characteristic irregularities, openings, Has cracks or pores of irregular size or shape, a large number of nests against each other with the formation of refractories Metal sections adjoining and a large number of the microscopic spots in the zone near the surface to the characteristic Irregularities have been created, giving the zone near the surface a noticeable coverage is partly created by the microscopic spots. 8. The object of claim 1, 3, 5, 6 or 7, characterized in that 809809/0610 draws that the macroscopic points together under formation a macroscopically continuous coating of the refractory metal on the backing metal. 9. The article of claim 1, 3, 5, 6, 7 or 8, characterized in that that the object adsorbs electromagnetic radiation of visible and infrared character more strongly than the base metal in a technically pure and uncoated condition. 10. The article of claim 1, 3, 5, 6, 7 or 8, characterized in that that it has a macroscopic gray color and visible electromagnetic radiation in a wavelength range adsorbed between 580 and 610 nanometers more strongly than an uncoated backing material. 11. The article of claim 1, 3, 5, 6, 7 or 8, characterized in that that the metal for the base material consists of aluminum, chromium, cobalt, copper, iron, magnesium, nickel, tin, Titanium as well as alloys thereof such as steels, cast iron, brass, bronzes and solder. 12. The article of claim 1, 3, 5, 6, 7, 9, 10 or 11, characterized marked that the refractory metal consists of boron, chromium, cobalt, iridium, molybdenum, niobium, osmium, palladium, platinum, Rhenium, rhodium, ruthenium, tantalum, thorium, titanium, tungsten vanadium, yttrium, zircon or alloys thereof. 13. The article of claim 1, 3, 5, 7 or 8, characterized in that that hydroxides, chlorides, nitrates, sulfates, cyanates, carbonates, acetates, oxyhydrates, oxychlorides and thiocyanates of the backing metal is provided as a means for attaching discrete particles of the refractory material to the backing are. 809809/0610 14. The object of claim 1, 3, 5, 7 or 8, characterized in that that this means for attaching discrete particles of the refractory material to the support a reservoir for further discrete refractory metal particles which are not in contact with the metal substrate, the further refractory metal particles impart longer lasting abrasion properties to the backing metal. 15. A method of applying a refractory metal to a substrate metal with relatively low wear resistance, characterized in that an electrolyte material capable of dissociating into ions and having a conductance between 0.13 and 0.93, calculated using a 0.1 normal solution , has, is used, a refractory metal in the form of discrete particles to be deposited in the zone near the surface of the backing material, the refractory metal having a melting point of at least 1490 ^° C., 99 to 50 weight -% of the refractory metal and 1 to 50% by weight of the electrolyte are mixed for a period of time sufficient to form a nascent surface on at least a portion of each refractory metal particle to be deposited, at least in part the refractory metal particles be surrounded by the electrolyte, a moisture content in the mixture is maintained sufficient to maintain a resistivity of the electrolyte of less than about 10 ohm-cm of the mixture, creating a concentration of refractory metal ions of 1 to 60,000 mg per liter of solution, the surface of the Base material is contacted with the mixture of refractory metal in individual particle form and electrolyte and at least partially coated, the mixture is ^{reacted with the base material at temperatures between Q and 200 0} C and the refractory metal in the zone near the surface of the base material in the form of discrete particles are deposited, whereby 8O98O9 / OS10 a protective surface is created for the backing material. 16. The method according to claim 15, characterized in that the refractory metal is deposited in the form of discrete particles. 17. The method according to claim 15 or 16, characterized in that the reaction is carried out at a temperature between 15 and 40 ^0C . 18. The method according to claim 15 or 16, characterized in that that in the zone near the surface of the base metal the refractory metal is deposited in a thickness of up to 0.5 mm will. 19. The method according to claim 15, 16, 17 or 18, characterized in that that the electrolyte used has a degree of dissociation of 0.60 to 0.93. 20. The method according to claim 15, 16, 17, 18 or 19, characterized in that that the electrolyte used consists of a mineral acid, an organic acid, a base, a salt of such Acid or base or an acid anhydride. 21. The method according to claim 15, 16, 17, 18, 19 or 20, characterized in that the refractory metal used is made of boron, Chromium, cobalt, iridium, molybdenum, niobium, osmium, palladium, platinum, rhenium, rhodium, ruthenium, tantalum, thorium, titanium, tungsten Vanadium, yttrium, zirconium or alloys thereof. 22. The method according to claim 15, 16, 17, 18, 19, 20 or 21, characterized characterized in that the refractory metal used has a particle size of 0.01 µm to about 1.0 mm. 809809/0610 23. The method according to claim 15, 16, 17, 18, 19, 20, 21 or 22, characterized in that the base metal used made of aluminum, iron, chromium, cobalt, copper, nickel, magnesium, tin, titanium or an alloy such as steel, cast iron, brass, Bronze or solder. 24. The method according to claim 15, 16, 17, 18, 19, 20, 21, 22 or 23, characterized in that the mixture of refractory Metal and electrolyte for a period of about 30 minutes to 30 days to produce the nascent or growing Surfaces is mixed. 25. The method according to claims 15 to 24, characterized in that that the concentration of the refractory metal ions is formed in such a way that the refractory metal particles with nascent Surfaces in contact with the electrolyte, and the specified moisture concentration for a period of 10 Minutes to 60 days. 26. The method according to claims 15 to 25, characterized in that that a reaction time between 1 and 168 hours is observed. 27. The method according to claims 15 to 26, _r characterized in that a moisture is "maintained from 0.5 to 60%. 28. The method according to claims 15 to 27, characterized in that that 1 to 10% by weight of a material is added to the mixture which serves as a means of preventing electrochemical polarization. 29. The method according to claims 15 to 28, characterized in that the agent used to prevent electrochemical polarization from MnO ₂ , CuO, rigO, platinum metal 809809/0610 powder, ionizable iron and tin halides, sulfates, nitrates or activated carbon. 30. The method according to claims 15 to 29, characterized in that that the product washed with water and containing the refractory metal by treating the refractory metal Drain with a mineral acid solution in an amount sufficient to adjust 1 to 10% by volume of the mineral acid, is recovered. 809809/0610