DE1521387B2 - Multi-component flame spray material - Google Patents

Description

In French patent 1313303 is a Described flame spray material consisting of several components, which consists of at least two Components reacting exothermically in the heat to form an intermetallic compound having. . .

The bodies supplied can be in the form of individual coated powder particles, in which one component the core and at least one layer covering the core the other component represents. The core mass is preferably made of aluminum and the sheath is made of nickel, it being expedient 10 to 45% aluminum, based on the total amount of nickel and aluminum, are present.

The heat-fusible material can also be in the form of wires or rods. Also in these In some cases, the wire should have an aluminum core and a nickel coating.

Such proposed flame spraying compounds can be mixed with other conventional flame spraying compounds be used. When using flame spray wires, the same requirements must be met be fulfilled, so they must also consist of two materially different components, which are able to exothermic at the temperatures developed in the heating zone with the formation of an intermetallic React connection with each other, the individual components structurally in such a way with each other must be connected that they are in intimate contact and melt during the spraying. The components can be in the form of wire strands.

The flame spraying material proposed here now delivers with a certain selection of the one in question coming ingredients particularly good results.

The invention relates to a flame spraying material consisting of several components, the minde-

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at least two metallic components which react exothermically in the heat and in the form of Powder grains are present, the core of which is one component and the shell of which is the other component contains, these components being structurally interconnected so that they can be used during the Spraying stand in intimate contact and melt, which is characterized in that the Core of the powder grains made of nickel and the shell lying on the surface of each powder grain consists of finely divided aluminum particles in a binder that decomposes in the heating zone.

As far as bodies are mentioned here, these are structurally one-piece units to understand while pure mixtures of the components that are physically without Destruction of the particles can be separated from each other, are not meant. In case of application of powders is in the bodies according to the invention not a simple mixture of Single grains of the various components thought, but it is imperative that every single grain contains the various components which exothermically with the formation of intermetallic Connections react with each other. In the bodies according to the invention, the components that is, to be in close contact with one another.

Should the heat-fusible material be supplied in the form of wires or rods containing the components care must be taken that there are no cavities or bubbles when melting together form. It has proven useful to use a wire whose sheath is made of aluminum, which is a powder Sheathed from nickel, the shell substance having to melt lower than the powder substance. The wires can of course also consist of single strands of two different components.

Nickel and aluminum, when melted together, are said to be about 300 per gram atom Free gram calories, preferably at least 7500 gram calories. The phrase "gram calorie per gram atom «denotes the number of gram calories that make up the average atomic weight in Grams of the reacting nickel and aluminum are generated. Although the components preferably in the stoichiometric stoichiometric values required for the formation of the intermetallic compound Conditions should exist, it is also possible to use an excess of one over the other, provided that the relative amounts are sufficient to generate the specified amounts of heat, which are necessary for the formation of the intermetallic compound.

Although iron is not in itself a useful ingredient, it can be added apply to nickel, for example in the form of an alloy. However, the nickel must then be present in quantities which are sufficient to generate sufficient amounts of heat for the spraying process to take place support. Accordingly, for example, iron that contains just enough alloyed nickel to Having become corrosion resistant did not contain enough nickel to work effectively with aluminum to react exothermically. In general, a suitable nickel / iron alloy for this purpose must be used contain at least 12% nickel.

The powder grains can also contain other common components used in the flame spraying process.

contain nerites, but can also only be sprayed on as a mixture or in conjunction with them. Correspondingly, for example, the coated powders can additionally contain other casings of others Have flame spray components, or additionally be mixed with any desirable ones other flame spray powders.

A preferred and very simple method of forming the coated powders of the invention is in applying the aluminum in the form of a coat of paint to the nickel. To this Purpose you can use the aluminum, which is to form the shell, in finely divided form in a binder or Disperse paint to form a real paint in which the aluminum is a pigment is equivalent to. This paint is then used to coat core particles of nickel, after which the binder or varnish is allowed to solidify or dry. The binder is preferably made of a resin that does not require evaporation of the solvent to a dried or to form a solidified film, the film decomposing or collapsing in the Heat of the spray process. The binder can, for example a phenolic varnish or any other known or customary varnish, which is preferably contains a resin as a paint solid. The aluminum to be mixed with the binder or paint should preferably be in as finely divided form as possible, for example in particle sizes of 44 microns. The nickel that forms the core should be about the same particle size as the final particle size for the wettable powder is required, correspond to or only slightly below this size. The coating of the The core component with the "paint" can be done in a known or desired manner, it is only required to mix the two materials together and leave the binder to dry or Bringing to solidify, whereby an almost free-flowing powder is formed, which consists of the nickel core, envelops with the aluminum that is distributed in the binder.

Although the powders are preferably sprayed as such with a powder flame spray gun, it is also possible to combine them in the form of a wire or rod using a Plastic or a similar binding agent that decomposes in the heating zone of the gun. the Wires must have the usual dimensions and accuracy tolerances specified for flame spray wires exhibit. Their dimensions can be between 6.4 mm and spray wire no. 20 vary, they are preferably at the following values: 4.8 mm + 0.0013 mm

- 0.064 mm
3.2 mm + 0.013 mm

- 0.064 mm
Wire No. 11 + 0.013 mm

- 0.025 mm
and No. 15 wire + 0.025mm.

The wires must be smooth and clean on their surface and no lines, spots or other Have errors. They are sprayed on in the usual way using wire flame spray guns.

example
Finely divided aluminum powder with a particle size of up to 44 microns was mixed with a phenolic varnish which was about 50% solids content. The mixing was carried out in such a way that a mixture with a consistency roughly the consistency of heavy syrup was formed and which contained 60% metallic aluminum.

100 g of this mixture of paint and aluminum powder were added to 240 g of nickel powder that was mixed with particle size between 44 and 74 microns. The two substances were mixed vigorously and mixing continued until the varnish was leaving a reasonably free flowing Powder was dried, in which all nickel core particles were encased with a dry film. The film consisted of aluminum particles that were attached to each other and to the core material by the phenolic binders were associated. The powder was then warmed to 120 ° C to complete Ensure drying. There were some

2 »Agglomerates in front of them, sifted out and then through Hand milled to a particle size of 150 microns. The final one Powder was about 15% aluminum and 85% nickel due to the loss of something Aluminum during grinding.

The powder obtained in this way was sprayed by the flame spraying method onto a mild steel plate which had been cleaned on its surface with an emery cloth. The spraying was carried out using a powder spray gun according to US Pat. No. 2,961,335 while maintaining a distance of 23 cm. 2.72 to 4.08 kg of powder / hour were sprayed on using acetylene gas as fuel at a pressure of 0.7 kg / cm ² . Flow through

Flow rate: 481-7101 / hour. Oxygen was under a pressure of 0.84 kg / cm ² and a flow rate of 820-990 1 / hour. used as an oxidizing gas.

The nickel shell and the aluminum core combine

4 «each other in the heat of the flame, giving off a great deal of heat and settled on the base in the form of a dense, high-quality coating, the self-binding one Properties. In the manner described, a layer of 0.05 to 0.10 mm Thickness can be built up. The covering can be used as the basis for spraying on further layers of different Metals, etc., it is an excellent interlayer connecting layer represent.

-) 0 You can also add a thicker layer to the topping build up, for example to a coating of 0.25 to 0.5 mm thick, which as an oxygen barrier serving document can serve. As described, even layers with a thickness of 0.5 Apply up to 1.0 mm and more as wear-resistant and oxidation-resistant surfaces. Thanks to his self-binding properties, the sprayed-on coating adheres without the usual surface preparation or roughening the surface. Corresponding

b (> according to the natural properties of a sprayed With a good bond, the coating enables further flame spraying compounds to be sprayed on. Even at high temperatures and in an oxidizing environment, the powder coated

h5 sprayed coating still has excellent resistance to oxidation, so that an oxidation of the base material, for example from molybdenum etc. exists, is prevented. The sprayed-on coatings

Can be used as cladding for metal crucibles or devices for treating molten metal Metals serve, they are made by many molten metals, including the self-fluxing alloys, not moistened or penetrated. The coatings that are formed also prove themselves to be higher Temperature wear-resistant pads.

The coatings obtained with the powder of this example have a tensile strength of 808.57 kg / cm ² .

If the procedure of this example is repeated using a molybdenum rod from 4.8 mm in diameter, with a 0.25-0.30 mm thick coating being sprayed on, the coated Heat the rod repeatedly from the air to about 1100 ° C using a welding torch, no oxidation being detectable after cooling to room temperature.

Claims (3)

Patent claims: 1. A multi-component flame spray material containing at least two in the Has metallic components that react exothermically and is in the form of powder grains, whose core contains one component and whose shell contains the other component, with these components are structurally connected to one another in such a way that they can be removed during spraying stand in intimate contact and melt, characterized in that the core of the Powder grains made of nickel and the shell of finely divided particles lying on the surface of each powder grain Aluminum particles in a binder that decomposes in the heating zone. 2. Flame spray material according to claim 1, characterized in that the reacting with one another Ingredients deliver at least 3000 gram calories per gram atom, preferably 7500 gram calories. 3. flame spray material according to claim 1 and 2, characterized in that it is additionally contains at least one further flame spray material.