DE2401817A1 - FLAME SPRAY POWDER - Google Patents

Description

DR.-ING. FROM KREISLE * DR.-ING. SCHG'i FOREST DR.-ING. TH. MEYER DR. FUES DIPL.-CHEM. ALEK VON KREISLER DIPL.-CHEM. CAROLA KELLER DR.-ING. KLOPSCH DIPL-ING. SELTING

COLOGNE 1, DEICHMANNHAUS

Cologne, January 15, 1974 . - Mr. / Breu

METCO, Incorporated, 1101 Prospect Avenue, Westbury, New York 11 590, USA

Oxygen fuel powder

The invention relates to a flame spray powder mixture which contains a self-fluxing alloy powder and a molybdenum-containing powder. When flame spraying this Mixture v / earth firmly adhering, porous 3 layers with excellent Wear resistance and very good load resistance obtain.

In flame spraying technology, a type of powder is known which is generally known as spray-weldable, self-fluxing Metal powder or simply as, self-fluxing alloy powder are designated. Such powders are described in U.S. Patents 2,875,043 and 2,936,229 contain a base metal, for example nickel or cobalt, and a component that provides the flow properties, like boron or preferably boron plus silicon. They are mostly used to remove melted deposits on substrates sis steel or steel alloys with the help of the known spray welding process. In the spray welding process First, the powder is sprayed onto the surface to be coated, which is more common Flame spraying methods are used, after which the present coating is fused in place. The merging is carried out, for example, in an oven, with the aid of induction heating or in a similar way but often by immediately heating the sprayed-on Surface with a welding torch.

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In the case of the spray welding process, flame spraying represents is even a simple way of depositing the alloy powder on the substrate to be coated in order to to enable the formation of a fused-together coating through the subsequent melting process. The one on this Way before do.:? Melting process =? sprayed on coating is po- ' rö's, does not adhere firmly to ^ rt and steep and is not in usable in the same way as those that were subsequently fused Deposits, i.e. it is not a hard, dense, wear-resistant lining. The particles of a sanding reworked, directly present in sprayed form coating can be, for example, with a Tape, like Scottish tape, from the backing pull off.

Flame spray powder mixtures are known from US Patents 3,313,633 and 3,378,392 which contain a powder of a self-flowing alloy and which are classified under special Temperature conditions with the formation of denser, more coherent coatings can be sprayed on in a certain way. Similar to the fused layers of the spray welding process without a subsequent fusing or welding being necessary. In these known powder mixtures are adjacent to the self-fluxing alloy is about 5 to 95 wt .- #, and preferably from 15 bis 30 wt .- $ 6 or older natively 70 to 90 wt -.% Of a Ketallpulvers of tungsten, 2henium, tantalum, molybdenum, niobium, and alloys 'of these metals. With the help of a plasma flame spraying process, dense, coherent coatings can be produced with these powder mixtures, which in a certain respect correspond to the fused coatings produced by the spray welding process, although here, too, the melting process is omitted. The sprayed coatings have superior 3 properties as storage areas and other wear-resistant and load-resistant surfaces.

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The coverings obtained in this way are sufficient for most purposes, but their production requires relatively high costs and requires very high temperatures, which are often above 22 cm- ⁰ C and in special cases even above 3326 ° C. For one of its uses' v. However, ^r ird called for greater wear resistance than achievable with these known Flammspritzmasεcn, also a certain degree-of porosity is required for certain applications.

The object of the invention is to provide a flame spray powder that delivers coatings that are directly sprayed on Condition, i.e. without subsequent melting, flawless are and are characterized by hardness and substantial density, but are also porous enough to hold oil in place. Abandonment the invention is also to describe corresponding flame spraying powders that are relatively inexpensive are, have coverings with very good wear resistance and high load resistance and are in the powder mixture of the flame spray compound contain a self-flowing alloy. The new flame fuel compounds should be flame-sprayable according to the invention at lower temperatures than was previously possible and independent of which can form coverings with the properties highlighted above.

The invention is based on a flame spray powder a mixture containing a self-fluxing alloy, which is applied directly to a base in the sprayed-on state forms a covering with good load resistance. It is characteristic that the mixture 5 to 95 Gevr.-S »one Iron-Kolybdenum alloy contains, based on the total weight made of self-flowing alloy and iron-colybdenum alloy?:, in this about 50 to 75 wt. per molybdenum and about 50 to 25 wt. Iron present.

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The invention thus represents a substantial improvement over that. Spray welding process of US Patents 3,313,633 and 3,378,392, in which a powder of a self-fluxing alloy is flame-sprayed onto a substrate together with a high-melting powder, the 5 to 95% by weight of the self-flowing alloy and a high-melting powder contains. According to the invention, an iron-molybdenum alloy is used as a high-melting powder which contains about 50 to 73% molybdenum and about 50 to 50% iron and forms a firmly adhering, porous coating on the base.

Hach a preferred embodiment of the invention, the iron-molybdenum alloy _-: .Approximately 58 to 65 ¥> molybdenum, 3 wt .-% · up, and preferably less than about 2.5 ^ carbon, less than about 5% impurities, such as Silicon, copper, sulfur and / or phosphorous, while the rest consists of iron. The cost of such an iron-molybdenum alloy is only a fraction of the cost of molybdenum alone, for example about 1/3 "to 1/4 of the price, although the quality of the linings is generally comparable and in special cases even superior Due to the special composition, the melting point of the iron-molybdenum alloy can exceed 1,930 ° C., be slightly below this temperature or even 55 ° or 110 ° C. lower if the molybdenum content is at the lower limit of the range.

The coating is not self-fusing, but is fairly dense, although not as dense as a coating made with unalloyed molybdenum. The porosity of the covering may be up to about 10 -p or even more, but is preferably about 5 ". Then the 3- = lag is able to hold oil and is therefore particularly suitable for special applications, for example with a Machine parts with lining, piston rings, etc., as detailed below.

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As described in U.S. Patents 3,313,633 and 3,378,392, the self-fluxing alloy powders used in the context of the invention are said to correspond to the known and commonly used self-fluxing alloy powders, for example, all of them come in U.S. Patents 2,875,043 and 2,936 229 in question. These powders are often referred to as self-fluxing spray-welding powders or, as spray-weldable powders, but the term “self-fluxing alloy powder ¹ ”, which is generally used here, is intended to denote these materials. Self-flowing alloy powders of the I-nickel or I-nickel / chromium type which contain boron and silicon are particularly preferred. In addition to the base metal, i.e. nickel and / or cobalt, and the flowing constituents, the powders can also contain additional alloy constituents, for example up to 20 % chromium, in order to ensure corrosion resistance and oxidation resistance, carbon in amounts of a few percent by weight, iron up to a maximum of 10% by weight and preferably at most 5 percent by weight, based on the total weight of the alloy.

A characteristic self-flowing alloy prof ~ spulver of boron / Hickel type consists of 0.7 to 1 wt .-; & carbon, 3.5 to 4.5 wt .- # silicon, 2.75 to 3.75 wt -%. Boron, 3 to 5 percent by weight iron and up to 18 percent by weight chromium, for example 16 to 18 percent by weight, with nickel making up the remainder.

A typical injection welding cobalt-based alloy containing for example, 1.5 to 3 wt .- # boron, 0 to 4.5 silicon fo, 0 to 3 wt .-% carbon, 0 to 20% chromium, 0 to 30 ^c / o nickel, 0 up to 20 % molybdenum, 0 to 20 % tungsten, remainder: cobalt.

The self-fluxing and the iron-molybdenum alloy powder should generally have a particle size below 175 microns. If you spray according to a special one Implementation of the invention with a plasma flame '

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the particle size should be between 0.5 and 175 microns lie. As is customary with flame spray powders, a narrower particle size range is preferred, uno. within the finer or coarser portion of this wide range. The self-supporting alloy should preferably have a particle size from 15 to 62 microns, the iron-molybdenum alloy Preferably between 15 and 88 microns. It is particularly useful if the particle size of both powders in a mixture is 5 to 20 microns.

The refractory powder containing molybdenum should preferably be in quantities of 15 to 30 wt% or alternatively 70 to 90 Gev; .- / 'j are present, based on the total weight the mixture of 'high-melting powder and self-flowing Alloy powder. The powder mixture of the invention is preferably sprayed on as such, it can be used but also use in a mixture or together with other high-melting powders, such as at least one of the Metals tungsten, hhenium, tantalum, iriobium and / or their Alloys, molybdenum alone or in other Veise, as described above cit iron alloyed. As additives Aluminum or fire-resistant carbides such as tungsten carbide, lantalum carbide, titanium carbide, etc. are also suitable or without an investment made of cobalt and / or liickel, also fire-resistant oxides, such as aluminum oxide or zirconium oxide, molybdenum disilicide, powder from exothermic reacting constituents of composite individual particles, as described in the United States patent 3 322 515 are described, etc. The powder mixture of the Invention can, for example, be sprayed on in quantities of 5 Dis 95 wt .- / j or preferably 10 to 90 wt .-; S, based on the total weight of the mixture, whereby the reading consists of the other added flame spray material.

The powder mixture is preferably sprayed on with the aid of a powder spray gun, for example a flame spray gun that works with combustion gas, where £

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however, temperature conditions must be adhered to in order to ensure the melting of the high-melting ketallic powder component. For this reason, the temperature in the heating zone must be above 2 204 ⁰ C and preferably above 3 871 ⁰ G. A preferred embodiment of the invention is used to spray with the aid of a plasma flame spray gun, for example a type in which a plasma flame is generated by combining an electric arc in a nozzle with a plasma-forming gas, for example with nitrogen or argon alone or in a mixture with hydrogen.

U.S. Patent 2,960,594 describes spray guns, which create a plasma flame in this way.

Spraying can also be done using a wire flame spray gun perform, with the powder mixture in the form of a spray wire or spray rod through a Binder is held together, for example a synthetic plastic. (See U.S. Patent 2,570,649). In describing the invention, the term "powder" is generally not intended to mean just powder in bulk refer to, but also Fulver present in bound form. In the latter case, the wire spray gun must have a ! Supply a plan of sufficient temperature to melt the refractory metal, for example a Plasma flame. Except for spraying simple mixtures the individual components present in powder form can also be sprayed on with composite individual particles which both the iron-molybdenum alloy and the self-fluxing one Alloy, in which case a powder consisting of such egg particles is used. For example iron-molybdenum particles of the type described can be used, but with one of finer particles of the self-fluxing alloy existing particles are encased. In this embodiment, the particles can self-fluxing alloy in the form of a very fine powder

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or staiibs of a particle size between 0.5 and. 25 microns, preferential prices between 1 and 10 microns, applied v; ground. These fine particles can be applied to the surface of the particles of iron-molybdenum alloy for example with a binder, v / ie a phenolic Resin. Other organic binders can also be used, as is a simple thermal one Bond or any other type of bond on the individual particles of the iron-molybdenum alloy possible.

Alternatively, the individual particles can also consist of particles of a self-flowing alloy of suitable particle size exist, which are coated with finer particles of the iron-molybdenum alloy. In this case nuts the latter particles are in the form of a very fine powder or dust and have a particle size of 0.5 to 25 microns, and preferably 1 and 10 microns. As binders to be used, if applicable, come the question mentioned above.

The powder can also be composed of individual Grains consist of subparticles from both the self-flowing Alloy as well as from the iron-molybdenum alloy contain. These powder particles can be in the form of a very fine powder or dust with a particle size between 0.5 and 25 microns, preferably 1 and 10 microns. The compound grains can be deformed, briquetted or tabletted according to methods customary in powder metallurgy technology, whereby was worked with or without a binder. But they can also be dried by spraying according to the U.S. Patent 3,617,358 obtained.

In all other respects the spraying becomes more familiar and usually carried out, especially as far as the spraying with the help of a plasma flame spray gun he follows.

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The coverings can be applied to common substrates, for example those made of iron and steel alloys for all purposes for which a wear-resistant and / or load-resistant Surface is required. Deposits with a thickness of 12.7 microns to 3> 17-5 cm and preferably between 51 and 762 microns can be formed and are extremely useful as wear-resistant Surfaces, for example for piston rings in internal combustion engines. The applied according to the invention Linings have also proven very useful for crankshafts, UaIζenzapf "s, bearing sleeves, impeller shafts, gear journals, oil pump impellers, screw conveyors, wire or Rope capsules, 3-arm drums, return forks, scraper knives, Yarn guides, farming tools, motor shafts, lathe tracks, lathe centers and grinding centers, Plungers, "cylinder linings. The surface to be coated should be pretreated in a conventional manner known per se , for example by blasting steel shot with air under a pressure of 7 kg / cm or by surface treatment on other known Vegen, for example by roughening, coating, etc. One can also use a common material that reinforces the bond between the base and the base, such as flame-sprayed Molybdenum, a molybdenum alloy or kickelaluminide, such as in U.S. Patent 3,322,515. Except Iron and steel can also be copper, brass, aluminum, titanium, molybdenum or other materials whose surface is suitable for flame spraying according to known "methods, with the flame spraying powder and using the procedure of the invention are covered.

Although the coverings obtained according to the invention are immediate in the sprayed-on state can take the place of the coverings obtained after the spray welding process using two work stages, they are with these fused coverings are not identical and

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in some respects even superior to these. They make a difference structurally in the fact that the individual particles of the Hochschiaelsenden Metal can usually be individually identified in metallographically prepared areas, and that the porosity is also higher. Although the No subsequent coatings according to the invention Merging, and generally used without it, may in some cases be used still melt together or post-treat with heat in order to to achieve a desired refractory alloy coating.

The following examples illustrate the invention, all specifications being taken as weight specifications unless otherwise indicated.

example 1

Were prepared from 25% of a self-fluxing alloy powder and 75? J different hochschaelzender powder flame spray powder, after which the mixtures were sprayed under particular conditions to a Flußeisenplatte to produce coatings, which were then examined.

The exact composition of the various applied Powder is given below:

Self-fluxing alloy, particle size 15 to 22

Micron.

Weight%

3 x 5.5

Si 4-

depending 4-

Cr 17

C '1.0

rest

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-.11 Hocfeschrnelsende powder

a) sine-i-olybdenum alloy; Particle size: 44 to

14Q. riikron.

Ho ^ 62.5

C '". 0.075

Si 0.83

Cu 0.09

S 0.11

p 0.032

Pe remainder b) iron-chromium alloy; Shieldalloy

Cr 66.7

C 6.4

Si 2

Pe rest

c) chromium

Cr 99.9

d) molybdenum. 44 to 88 microns.

The powders were mixed together as indicated and among those indicated in Table I below Sprayed on conditions to obtain coverings which were tested for abrasion resistance as follows became:

1.) Measure the thickness of the test buttons (including the covering) in four places using a super micrometer and noted the measured values. (The four places are marked

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240181?

for a subsequent measurement by adding markings or numbers to the circumference of the button).

2.) Each button is weighed exactly with an analytical balance and notes the weight.

3.) A drive mechanism is inserted into the spindle of a drilling machine.

4.) You put a table balance on the table of the drill, pull the arm (handle) of the drill down into a horizontal position and fixes it in this position. '

5.) Lift the table of the drill up to the drive mechanism a load of 11.34 kg on the table scales indicates.

6.) You unlock the spindle of the drill, a weight hangs on its arm in such a place that the The scale shows 11.34 kg and marks the point where the scale shows this value on the arm of the drill.

7.) You remove the scales.

8.) The spindle is lifted and the setting pin is replaced with a blind pin of 31 »75 mm.

9 ·) You put two test buttons on a wear track, lowers the spindle until the driver pins engage in the driver holes in the buttons, and locks without loading the Buttons-

10.) Turn on the drill, pour a well mixed slurry of alumina abrasive powder into the bowl (Metco 101), particle size 15 to 53 microns, in a slurry of 25 g abrasive in 200 ml

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Lighten machine oil and release the lock of the spindle, so that the load of 11.34 kg on the test buttons rests. The starting time is noted.

11.) The test is allowed to run for 20 minutes.

12.) Remove the test buttons and wash them in one Solvent. Weigh it, measure its thickness and record the readings for comparison with the original values.

The hardness numbers are determined using the Rockwell standard hardness test method (Ra scale) or the hardness test method determined according to Knoop at 50 g load (KHITj-q). the The porosity was measured with the aid of a metallographic technology known standard method. The test results are also shown in Table I. leads.

Although there is a relatively high porosity of 5.5 % , it can be seen that the wear resistance results using the powder (a) according to the invention are surprisingly far superior to the other substances tested. The iron / molybdenum containing mixture was the only one that showed a desired combination of porosity with excellent wear resistance.

The Metco 3 MB type spray gun used for spraying is a common plasma flame spray gun that uses a Has housing with an axial cathode which is surrounded by a ring anode designed as a nozzle. A high one Arc current is established between the electrodes and a first gas flows through and out of the gun Nozzle, which is heated to plasma by the arc. Immediately behind the nozzle outlet, one becomes Storage vessel in a second gas (carrier gas) powder introduced approximately radially into this first gas in order to through plasma to be heated and centrifuged. ■

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Panel I.

Mixtures of 75 % cLes high-melting powder and 25 % of the powder of the self-fluxing alloy

Plasma bottle injection • iron /
chrome Refractory powder Iron / molyb
Danish something
carbon molybdenum bedinscuns; eii chrome (SOritz pistol
Type Metco 3 MB) 5.1 5.1 7.6 Nozzle (mm 400 5.1 500 300 Amperage (Amp.) 50/50 400 50/50 50/50 N ₂ / H ₂ pressure 100/5 50/50 100/15 100/15 No / lLj flow rate
speed No. 2 100/5 No. 2 No. 2 Powder exit ⁺ 283 No. 2 283 283 Flow velocity
age of two
th carrier gas
(1 H.) 283

Application speed (kg / hour) 2.72-3.63 2.72-3.63 4.54-9.07 5.44-5.9 Spray distance (cm) 5.1 - 7.6 5.1 - 7.6 5.1 - 7.6 10.2 Measuring wheel S S .S S

Examination of the 3 layers

Macro hardness ⁺⁺ 77 70 69 70.5 Micro hardness e,) large e
KHITO ₁₅₀ ) phase
^ small
phase 740 646
858 963
735 - Powder / mi) _p .
hardness) S ^r - ™ ^ase
KHN ₅₀ ) kl. ^ft 1563
912 - 1129
1198 - porosity 6.0 3.0 5.5 1.2 Weight loss,
% of the standard sample 94 115 67 103 Loss of thickness, %
the standard sample 114 1 ^ -1 73 118

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The designation "powder outlet no. 2" characterizes it with the applied Metco plasma flame spray gun 3 MB shows the position of the outlet of the second carrier gas and the powder in the longitudinal direction of the cathode.

The hardness tests were carried out according to standard methods, which are described in the "Research Laboratory Report" Kr. 106, "Evaluation methods and equipment for flame spray coatings," available from Metco Inc., Vestbury / New York 1150, has been published.

At Soiel 2

Instead of the iron-molybdenum alloy of Example 1 became a high carbon iron-molybdenum alloy of about the same elbow size distribution and cost applied, which however corresponded to the following analysis:

Mon 62.5 C. 2.3 Si 1.1 Cu 0.09 S. 0.11 P. 0.03 Fe rest

The sprayed-on coating had a wear resistance that was almost as good as that of a coating in which Molybdenum was present alone as a high-melting substance. There was a slight tendency to seize when dry note which was apparently the result of a carbide phase contained in a larger particle; it is believed that this tendency would be eliminated if the carbide phase were present in smaller particles.

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In comparative tests without the self-fluxing alloy, the coatings made of a high-carbon iron-molybdenum alloy showed a high macro-hardness
(Eo 65 - 72) and were relatively porous. They contained carbide-like particles with a microhardness of 174Ό to 2,503 KHIi ₅₀ . When tested in aqueous mud, they wear out twice as quickly as the linings made of 75 % molybdenum and 25% self-fluxing alloy. The test for pitting in the dry showed deep cracks in the cast iron plate.

Deposits made of sprayed-on iron / molybdenum with a low carbon content, ie those that did not contain a self-fluxing alloy, showed significantly faster abrasion in aqueous sludge than that in the test
Mixture.

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Claims (8)

Claims 1.) Flame spray powder made from a self-fluxing alloy containing mixture, which forms a coating with good load resistance directly in the sprayed-on state on a base, characterized in that the mixture Contains 5 to 95% by weight of an iron-molybdenum alloy, based on the total weight of self-fluxing alloy and iron-molybdenum alloy, in this about 50 to 75% by weight molybdenum and about 50 to 25% by weight Iron present. 2.) flame spray powder according to claim 1, characterized in that that the iron-molybdenum alloy 58 to 65 wt .-? a molybdenum, up to 3% by weight and preferably less than about 2.5% by weight Carbon, contains less than about 5% by weight of foreign matter and the remainder ■ iron. 3.) flame spray powder according to claim 1 and 2, characterized in that that silicon, copper, sulfur and / or phosphorus are present as foreign substances in the iron-molybdenum alloy. 4.) flame spray powder according to claim 1 to 3 »characterized in that that in the mixture 15 to 30 wt .-% of the iron-molybdenum alloy are included. 5.) flame spray powder according to claim 1 to 3 »characterized in that that the mixture contains 70-90% by weight of the iron-molybdenum alloy. 6.) Flame spray powder according to claim 1 to 5 »marked through a particle size of 0.5 to 177 microns. 7.) flame spray powder according to claim 1 to 5 »marked by a particle size of 15 to 88 microns, 409830/0827 8.) A method for flame spraying the powder mixture according to claim 1 to 7 »characterized in that the mixture using a plasma flame on a pad splashes on. 9.) Method according to claim 8, characterized in that
that the sprayed-on coating is then melted together by heating. 409830/0827