DE1446117A1 - Diffusion coating process for metals - Google Patents

Description

The invention relates to the diffusion treatment of clay Metals for the purpose of producing a coating that increases the external strength and has increased oxidation and thermal shock properties ability at high temperatures »and evar particularly on the production of such a coating, which contains aluminum, Qirom and silicon, by diffusion application technique on various objects, which are made of the so-called" superalloys ", such as high-nickel and high-cobalt alloys, exist for high temperature retention purposes · di · metallurgical Development in recent years has the expediency tone heavily niokelhaltigen and b »w. or heavily cobalt-containing i * gie (sometimes as "S" perlegieru "g" n beaseieJuset) bese & eers

for A "we""u" gen at high temperature, Aa they deserve physical requirements for various kinds of high temperature applications, "" Β "for the production of T * a reterno dummies cnWI stator blades in high temperature gauzes, sit * where 4er Operation without failure of these parts over 1 & η $ * τ · periods · el temperatures «rheblioh over about · 13 * C (1590 * r) mm« cowardly vcseatlieh above the temperature range «aee erfelf · * eell,» ei welehem ei »waste the reetigfce £ te * ife * »« * af * e33 · β «Β» at a «« teaitisehea throat temperature- e «er Miekel- e * er? 3areme * aiae * • it expect«! is*- '·'

509812/0655 bad orhsinal

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Although nickel, cobalt or other superalloys for various uses have physical properties within a desirable range, especially when used at extremely high temperatures, are sometimes the oxidation resistance and / or the erosion resistance of the surface of such alloys, the resistance to thermal shock and the strength * properties especially when the objects are exposed to high temperatures and considerable temperature fluctuations for a long time are less than this for extended use or sharp Stress is desired »The above is of particular importance when it comes to the fact that such high-temperature superalloys are to be used for various machine parts, which even when operating at temperatures close to or within the range of the softening or melting temperature of the metal itself and under certain conditions Must have strength where thermally induced softening or warping and / or caused by thermal shock Damage for most favorable successful operation of the machine is not portable *

If you test the oxidation and heat resistance of the surface of such high-temperature alloys Increase the diffusion application of a metal such as chromium according to the usual diffusion application technique, to come tin "certain increase resistance to oxidation and other properties can be ascertained, but it has come to pass that I read increase does not correct the desired path, especially if you see it in order to use fttr ä * fiorat near temperatures aaadfri-t * if one on the other hand £ · * £ · «feea? all. · -li» kika »t · * ·" ftoe i die ffsvttnsohtvn Ofeerf läeheneigsaseaaften etci solehtr dadureh au heal, because one then «tears OfrernHekeaauitra ^ au» Aluminum, s.B. by eiae Alumlaiinmtauaauag aad dergl «, such an order may be owar anfä & glioh di®

h * aen temperature «a« t »l | i» t jsit, a 2Hffusieas order from AIu mlaiu »ita * see eia» lolnriartglc ·! «toeasilgliek 4» r ψ · η Alumiaia »wmd eiaifen n * 9S» tnilis »a $ ff * ki »nd ··. Metal · on aadar · i & yiikali «*» * «the eetail« wriieeft ·

of the superalloyste, iles determine.

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alloys ίνο ^ ΐκΙΙΙ Q ^ l, i.?^b^lfe^tp^~d^^^4^$^i^seiieÄ^ i? xii: c

a Diffiisionsauiiitrae-: # 3a * eir'r ^ & oSsttiffl ^

die. ". Otte ^ f lH ^ h

Pestigjieit violins ι oxidation,

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Substances obtained iU

shafts, dg ^ o

In case of high temperatures, gf rise apt _e ,

· ;. ^^ A '-' Mfgäb ^ d # r TBrfindung is

Diffusion overgrowth of increased strength against Erosion and heat impact on metal objects of the specified egg Kind, especially at high temperatures soie ^ -zirecKs ^ r ^ e ^ luiig increased strength properties for the coated article when exposed to high temperatures on its surface a diffusion application of a ^ combination, of. Possessing materials according to the invention shows increased resistance to oxidation in use and It gains strength properties especially at high temperatures to which it is exposed during use.

The subject of the invention is a diffusion cone au · silicon, chromium and aluminum in the surface of high temperature alloys, such as such · which have a predominant nickel and bsw. or have a cobalt base "whereby look at the surface of the object especially during its" use Higher temperature increased resistance to oxidation and increased Festi ^ ceit result

A further object of the invention is to create objects from a predominant iii, "kelk" ltigem u "* hmw " * the cobalt-containing orundleffiensmgatite "!" He practically k "nti" ntierlichen surfaces or tUittllmtc dl "aren

809812/0628

BATH ORIGINAL

Diffusion deposit is generated and silicon, chromium and aluminum in order to increase the resistance of the object to oxidation To increase thermal shock resistance and other strength properties, especially when used at high temperatures.

Other objects and advantages of the invention will appear from the following description

Before going to more precise execution »form the technique and. The objects that are obtained according to the invention are discussed in detail, it appears expedient to first consider certain aspects of the circumstances and areas of application in which the increased advantages according to the invention can be particularly valuable The invention is particularly noteworthy, but not limited to cases where a variety of metal objects are used in areas where substantial mechanical strength and resistance to warping and thermal shock while being resistant to oxidation for extended periods of time at temperatures in excess of about 1100 ° C (200G ⁰ F As is readily apparent, such high temperatures are generally considered to be above the temperature range where even austenitic high temperatures are essential. Quantities of nickel or chromium lose their strength even up to the point of collapse "Although the teaching according to the invention can be used to achieve satisfactory and advantageous diffusion jobs on such iron objects," their applicability also seems to be given in practice to such objects, where the advantages in. Compared to the application of the invention to increase the end properties of objects formed from superalloys, they are less pronounced.

These superalloy rings must be similar to that here possible alloys containing high nickel and cobalt the so-called refractory metal · such as molybdenum etc. are differentiated which are also common catfish for metallurgical · high temperature applications and possibly within the working temperature range Much above 815 ° g «is needed w« rd «n · It is J · -

■>, i909812 / 0625

dooh. to emphasize that the casting and metallurgical properties of the so-called refractory metals and their alloys inevitably entail certain difficulties or limitations in the casting, deformation and / or manufacture of parts or objects from such metals, which during the treatment, during casting or machining, "ψολ. objects manufactured from so-called super alloys, as they come into consideration here, do not stop or are largely avoided certain object or part for high temperature use, also because of the inherent limitations in casting, machining, etc., "are not considered regardless of the high-temperature strength of such metals", while the silver alloys, the corresponding properties for casting, machining or production of the Possession of the object s, do not have the desired high degree of moisture, resistance to oxidation and resistance to thermal shock at the desired high temperature for the intended use of the object.

In such cases, in accordance with the invention, a base alloy that is easily cast, deformed, or machined into the desired article can be used Manufacture are used, and the oxidation resistance that WSrm * impact resistance and the high temperature strength properties of the molded article or part are then recorded in satisfactorily by increasing its diffusion application, Finally, the first coated and finished object has favorable properties and desired capabilities to surrender

VI · it should be noted for further explanation, it was desired to produce a gas turbine inlet valve with relatively 4 * ηη · η walls g * zAl the so-called? RäslsiensguJe * er ^R v «rl« r «nen Vaekftprev · *", β · dal Aas Desired <Η · §- e * er Fermgulverfakren a * · »· Fllftlfftalgk ·! * * ·· sehmelzenem !! •« «lies mm ·! ■ ** · *> · giee *** i» e «ani ·· * · Un * metallmrglsohe 4af * r4 «rumg« m * «±« er Fersam * ··· Flm «* le v« rlangt · », <i · · ϋ» - ■ it spoles · * · ** »feaerfesten« "he

909812/0635

metals or alloys could not, or only with difficulty, be brought into the mood, from which one could expect aioh, that aie the desired thermal stability among other things high temperatures, for which the wing was intended in the brewing. When casting the wings atark cobalt-containing superalloys, adequate casting, molding and deformation techniques applied and corresponding results-obtained · After the molding of the wing was in its surface a diffusion coating or an Ifa coating made of silicon or aluminum and chromium produced according to the invention, and it was found that Such methods not only increased the resistance to oxidation at high temperature to sufficiently high limits, but also increased them The overall capacity of the wings had increased at high temperatures and was less prone to warping and damage Värmeatoß in use made -all this to an extent and with Temperatures that were above that of the bigenaoha adhering to the superalloy aelbat

In another case, using the production of the so-called beehive or slat construction, sounding aua flat sheets or sheets with corrugated layers in between Parts to increase rigidity and strength at mügliehat there was a slight increase in weight for the manufactured board Material used from rolled sheets of cobalt-gold superalloy of about 0.25 mm (0.12 line) thickness · When applied of the silicon-aluminum-chromium-Dlffuaionagabeea according to the invention on the Sohiohtkometruktlen after the production was the Compressive strength to about twice that of the urapreney value with effective additional strength in the finished construction, increased, waa anaeheinend on a Verbiadunga effect the seams «resemble the flat panels and the corrugated Sharing was based on what came to me, that increased «metallurgy and

4oa tulle aureh alloy with the were granted »

Whether it is the case that wmA is another “explanation no”, you see “fc * rBUge” md d · »irflaAsAf whr as just one“ 4g “rte 0 * 7 ·

ORIGINAL

rungen «They ·· overhangs also seem to influence the final metallurgical properties of the finished object Su as well to produce certain additional mechanical properties, dl • loh. not entirely a purely metallurgic function or · 1η · ηι metallurgical mechanism BUiohrtibtn lasitn. For example In accordance with the invention, coated-alloyed objects have been found al · structurally healthy and retained sufficient «firmness or thermal shock resistance capability for dl purposes, for dl si b «i temperatures were used at which the lowest • The ear-end component of the »basic teaching; core» of the subject · s actually look at or above the temperature of the » Erw «iohuii £ s- or Sehsielxpunkt ·· is located. That means one thing Example, proved that the biffuslon coating is practical the thermal stability and high temperature resistance de Oegen · tand ·· Ixt increases in temperature ranges that have been borrowed are above those at which the unsupervised "base alloy" would lead one to expect a "satisfactory" function and add to that There is also the resistance to oxidation, etc., which the olffusion order of the Ob-rflach-d-coated Oegenatandes give can·

As found in accordance with the invention, the advantageous production "inside" the outer coating or "1η" β application from a combination of clay silloium, metallic chromium and metallic huminium, especially on surfaces made from niokei-containing and / or, or cobalt-containing Superalloy by blffuslen in the surface of a base or coating clay, which is increased resistance to oxidation and erosion, as well as a lishtillung clay of good and uniform adhesion to the orundoietal object even when exposed to heat and deformations that the object can be exposed to during use ) In addition, such a seam significantly increases the high-temperature strength and the resistance properties of the object, considerably compared to those that can be achieved by means of Piatier or immersion and even diffusion of silicon or chromium or aluminum alone or separately as a coating or Wrapping on each gets owned basic alloys d · · · character on di · see '1 × invention relates j.

909812/0626

' - '" BATH

As Ton himself understands, the property of resistance to thermal shock is of particular importance in the case of high-temperature metal parts, and it is in fact a property that is somewhat related to high-temperature oxidation resistance, at least insofar as the production of an oxidation-resistant coating on high-temperature alloys exposed to severe thermal shock conditions are, becomes meaningful; if the oxidation-resistant coating or the outer covering to be assumed does not remain uniformly coherent during use and does not adhere so firmly to the object during the thermally induced deformation that bites or other interruptions in the oxidation-resistant coating occur as a result of the heat exposure can «» Once such hoists have occurred, they provide easy access to the base metal of the object, with the consequence of its oxidation and corrosion materials is also reliable enough to give to the subject of some further strength properties at high temperatures of this magnitude ^one that normally would cause a softening of Grnadlegierung, from the original cast, the part or otherwise Weis © formed iet _o

In the same context, however, it should be noted that the same high level of oxidation resistance or other strength-enhancing properties as well as resistance to thermal shock need not necessarily be present in all types of high temperature resistant coatings which may be used for the protection or improvement of superalloy parts and that one or the other deviating technique can be particularly used to concentrate any of several optimal properties, each of which can be regarded as useful or ultimately important for a particular purpose ·

To explain the above considerations, a üinlaSgaeturbinenst & Torflügel constantly to the extreme thermal shock

909812/0626 BADORiGfNAL

be exposed and in use a temperature differential ▼ on Tielen 100 ° Over the very sehmal width of the wing are subject to »x * B when one edge is exposed to the hot turbine gases, while the other edge is exposed to gases at temperatures much closer to room temperature "With such a use, the property of extreme thermal shock resistance of the diffusion coating may be desired to an extent that outweighs properties of increased strength and / or long-term oxidation at elevated temperatures." In such a case, one can choose a diffusion or surface coating technique that is extraordinarily high Impact resistance creates or increases ^ even at the expense of oxidation resistance or other strength properties.On the other hand, a situation may arise where, regardless of the thermal impact characteristics to which the part has been subjected, the installation or application in question is a superalloy casting or requires an object that can withstand prolonged exposure to an oxidizing atmosphere at high temperature, which requires high temperature resistance to oxidation for hundreds of hours at s "B" 4400 ° C (2200 ^o F) or more For the diffusion application of a protective layer, even with the same superalloy, choose a material or a technique that increases the resistance to oxidation, even if this property is to be retained at the expense of thermal shock resistance «

The preceding notice is particularly noteworthy because, of course, there are many special treatments for superalloy castings or other parts for the purpose of enhancing one or the other their end properties can be given, by means of which one can emphasize certain end properties at the expense of others, while surface applications or coatings according to the invention are provided in other cases with increased properties for a particular use, even with the same base alloy can · For example, a simultaneous proposal relates to the coating of hoohkobalt-containing or hoohkobalt-containing Superalloys by diffusion with an applied coating made of a combination of chromium and aluminum

9 0 9 8 12/0626 _BAD original '

1445117

stands for the oxidation resistance and heat shock resistance -of Metal objects increase, and it has been found that such Diffusion coating layers may be useful for any purpose for which the different silicon-chromium-alurainium diffusion coating according to the invention may also be useful is useful, but there are important differences between the two techniques and their results

Not to mention the strength-enhancing properties at extremely high temperatures, such as those that are coated Superalloy articles according to the invention, it has been found that in some uses the chromium-aluminum of the other proposal gives practically no thermal shock resistance slightly above that achieved by coatings according to the invention, while at the same time no oxidation resistance properties in this one given order of magnitude a high temperature machine part where the indications require that the continuously processed object without loss of thermal shock, e.g. "B" 600 Change from rapid heating from room temperature to approx. 8f5 ° C and subsequent rapid extinguishing resists, so holds an object coated according to the invention, 800 such test changes without failure, while objects, which are coated according to the older proposal * can withstand 1000 single changes. This means that although the coatings according to the present invention have the thermal shock resistance improve the superalloys unusually to an extent that where parts made from it pass the strictest usual tests should be prohibited, however, these coatings are not yet to be prohibited the special characteristics lead to the same extent as the Chrome-aluminum applications according to the other proposal «

But if other properties of the finished part are still of greater importance, they have become none the less fewer diffusion coatings or surface layers that consist of a silicon-chromium-aluminum combination according to the invention exist, have been shown to be capable in other relationships of delivering results that are significantly above the results, the Btu either with the untreated alloy part, the same

Λ: .-: -> · / -.> ^: '.' Ö 0 9 8 12/062 5

Part with a diffusion coating either of silicon or of Chrome or aluminum alone and or with the same part a diffusion coating made of two of these three materials. For example, coatings according to the invention can » apart from the increased strength properties that a metal object according to the invention at temperatures close to the softening * or melting point of some constituents of the base alloy are given an oxidation resistance, those significantly above previous coatings including those according to the older suggestion, namely by 20% or more " If, for the intended use of the finished part, clay is more of a decisive importance than resistance to thermal shock, it has been found that various objects or machine parts which, according to the teaching of the invention and have a diffusion deposition layer of silicon, chromium and aluminum, in the usual Test to withstand oxidation up to about 1200 C without failure, while similar superalloy parts do, even if they do treated according to the other suggestion mentioned, error results at perhaps 1100 ° C from the standpoint of the final or provide extended resistance to oxidation over several 100 hours at such high temperatures *

Vie from a comparative assessment of the above Discussion is evident, one must clearly keep in mind that it is probably possible to use some of the refractory metals or their alloys or so-called cermets of oxidation resistance and / or thermal shock resistance of that mentioned above An order of magnitude to be used. But such a possibility is more often out of consideration where the invention is an appropriate one Treatment of castable and easily malleable super alloys relates to imparting the desired enhanced end properties to the article cast or molded therefrom, which are required for the respective application · Also must all comparisons between one or the other property of the Temperaturweehselbeständlgkelt or oxidation resistance or Strength-enhancing properties that such super-settlements and objects made from it through a surface covering

909 812/0625 ^^, m-m

ORIGINAL BATHROOM.

Zug - especially with the »specified temperature ranges in consideration of the desired properties and to be appreciated in view of which of the several Properties for the special purpose of use Always straight “Although b © ispielsweis® s © probably the covers are required of the present invention as well as di® according to de® ob @ n mentioned older proposal -different degrees of temperature change resistance deliver, both sides are above the usual requirements for temperature change resistance

If, on the other hand, one considers, for example, a turbine blade or another part of a gas turbine engine of a given design, then, despite the fact that both application methods from the same superlayer would produce a metal object or a part that would be more than satisfactory for the particular stresses on the part with regard to the Thermal shock resistance would be, the failure of the coating according to the other proposal at about 1100 ° C does not meet the requirements of the special application, which requires an oxidation resistance ₉ after which the part over longer periods of time. must withstand a temperature of more than 1200 ° C (2200 ⁰ F) without error «Since the various industries require that such easily cast and yet high temperature resistant materials are to be developed today, especially with regard to the specified extreme temperatures, a machine part or an alloy object consisting namely a test to oxy since ti onsfestigkeit up to about 1100 ° C (2OQO ⁰ F), but the test does not attshält at about 1200 ° C (22ÖÖ ° F), as does a treated according to the invention relates does not just "not quite as good" as an item "coated or treated in accordance with the invention" In fact, it is unsatisfactory and useless in a situation where the higher degree of oxidation resistance provided by the present invention is required *; v " ■ - '''.' - '■■ - ■ - ■ ./'- " ■ -. -

Ε «can, therefore, give superalloy objects, their Surface treatments allow them to be used according to the invention Coated objects in terms of a single

V 'Λ 909812 / 062.5 "BÄ & Ö _RIGINAL _

Property of thermal shock resistance are superior, but nioht can withstand an oxidation resistance test at such a temperature level as the articles according to the invention. There are also refractory metal or "cermet" articles that withstand the oxidation resistance test and / or thermal shock impact far better than objects treated according to the invention, but it is precisely the refractory metal, from which they are made, the use of such materials in the molding of the particular objects on which the Invention relates *

By producing a strength-increasing, oxidation-resistant and heat-shock-resistant distortion or a surface layer made of silicon, chromium and aluminum, it delivers the invention lends itself to castable, malleable or machined machinable superalloy objects a finished product that meets the requirements, tests and characteristics, which are obtained for the high temperature machine parts or metal objects! and these enhanced benefits are made according to of the invention is achieved notwithstanding the fact that the methods, processes and articles obtained thereafter according to the invention not necessarily need to surpass all other objects with regard to all high-temperature properties, such as themselves from the above explanations results

Although the methods for coatings according to the invention cover various subjects in a satisfactory manner different metal alloys are applicable, as mentioned above, they are particularly adaptable to use in the case of base metal alloys which have a substantial or predominant proportion of nickel or cobalt, a.B. such Super alloys, as they are especially for high temperature purposes are composed and have physical properties as well as a useful life according to the requirements if they are very high temperatures for an extended farmer, and also have very sharp heat surges from rapid Weonsel or are exposed to large temperature differences over wide areas

Purely to explain the types of high temperature

909812/0625 _{& A} D ORiÖlHAL

Alloys for which the invention is particularly useful »mention should be made of a commercially available Niekel-based alloy traded by the Ut ie a Metals Division of Kolaey-Hayes Corporation under the designation" Udimet 500 ", as well as a commercially produced cobalt-based alloy, which is traded by the Haynes-Stellite Division of Union Carbide Corporation under the designation ^Ν Χ-Λθ ^η and another cobalt-based alloy which is also manufactured commercially and ^{traded by Haynes-Stellite under the name n} HS-25 "» Solehe Alloys have approximately the following compositions based on the manufacturer's specifications in weight percentages

Hoohniokelhaltige Alloy ι ("Udimet 500") carbon 0.12 ^ chrome 19 % cobalt 19 % iron 1 7 * molybdenum 4 % aluminum titanium nickel rest Those who are cobalt-rich Alloys! ("X-40 ⁿ ) carbon 0.5 % chrome 24.5 % nickel OK, 5 % tungsten 7, h% iron 1 % cobalt 33% («HS-25") carbon 0.1 * chrome 20% nickel 10 y VoIfram 13 * cobalt 50% Iron (approx) rest

Serve to explain the type of base material with which satisfactory results are obtained according to the invention the high temperature control steels, especially low austenitic ones Steels and very fillet-resistant steels and alloys with Substantial proportions of nickel and cobalt, even as mentioned above, compensate for the illuminated dislocation according to the invention practical, economic or commercial reasons less

"■" - '■. 90S8T2 / 0625

are more pronounced than in the case of the above-mentioned nickel and cobalt super-ions *

In order to further explain the process »Coatings and methods for carrying out the invention, it should also be emphasized that that the objects made of such high-temperature alloys, for which the invention is particularly adapted, are produced or coated in a satisfactory manner by methods which involve embedding the metal object to be coated in a dry powder combination with an inert one mineral filler material, a source of silicon, Chromium and aluminum are essential for diffusion and are a source of a vaporizable halogen material. " If you have items in such a pack -those preferably Is contained in a metal container or a retort, the edges of which are covered by a melting material such as low melting point silicate are sealed to prevent excessive escape of the diffusing

Materials during heating and also excessive penetration

- - ^v to

Sound air into the pack while cooling / preventing-in

in a manner known per se at a considerable temperature several Heated for hours to achieve a diffusion application of the desired Materials in the surfaces of the (non-round metal objects in To bring about connection with the elementary halogen reaction agent etc * »

Satisfactory results are according to the invention in such a coating of metal objects ^ the one from one

of the alloys mentioned by way of illustration have been formed using a tfoerzugspaekung which, as an example of the invention, consists of approximately 60% alumina as inert mineral filler, 30 % chromium metal, 8 % aluminum metal, 2 % silicon (the latter as the three components for forming the Diffusion orderβ) and up to 1 % ammonium iodide as the vaporizable halogen source. «The percentages relate to the weight. With such a packing enclosed in a container in a manner known per se for the production of diffusion for different materials on different metal alloys, satisfactory results have been achieved according to the invention by the objects

909012/0 62 5; ^ ₀ or, g, NAU

nit the high nickel or cobalt content in such package bi k · 20 hours at temperatures of about 900 ron heated to 1150 ° 0 (1650-2100 ⁰ F) ·

In the * assembly «? with the -vorstehenden areas should be emphasized that "if thinner · tJberzugs layer ene or wrappings are required, i.e.," h ₀ vo sharp heat shock "and deformation of objects to be accepted, the Diffusionsauf- contract preferably at the lower temperatures and BZV" or during Shorter times can be carried out within the above-mentioned ranges.For thicker coatings or coating strips are desired (e.g. where resistance to oxidation and BrO β ions and an increase in strength are of greater importance than the ability to withstand the possible destruction of the absorbent material or the coating by heat impact) the diffusion application measure carried out at higher temperatures and up to or over longer periods of time.

As will be readily understood by those skilled in the art of diffusion coating of metals, the proportions of the materials and the materials themselves used in of the above-mentioned packing have been proposed, can be varied over a wide range · So is the proportion of Inert filler is not critical, and while alumina is the preferred filler for such a packing, others are as well inert fillers satisfactorily give Zn like catfish other halogen sources than ammonium iodide on producing results? such as, for example, elemental iodine, ammonium fluoride, etc., provided that they are able to contain a vaporized halogen the temperature and under the working conditions, so because the halogen as a transmission medium or exciter or aid for the introduction of silicon, carbon atoms and aluminum or the intermetallic complexes of which act on the surface of the metal object to be coated Grade · 4 · naaa der Dieke 4 ·· coating or the anßenaohlcat can be modified to germinate. Satisfactory · »* · Results are old

9098 12/0625

on the order of 0.025 to 0.05 mm (θ.00t to 0.002 inches Thickness), although even thinner, coatings are essential increased oxidation and other protection for the base alloy and increase their strength properties · For some applications, thicker coatings may be required.

Similarly, the relative amount of chromium to silicon to aluminum in the material, the diffusion coating or the coating layer can be modified depending on the final properties required. Of course Gleiohgewichtsbe- can conditions regarding the halides of coating materials as well as fairly wide of the intermediate or intermetallic complexes over regions are obtained · It is eg au notice ,, that with increasing aluminum proportion will get a slightly raubare coating surface in the diffusion coating, especially in alloys in which the iron constituent is greater than in the alloys mentioned above, and that the depth or thickness of the deposit and particularly its aluminum constituent has some influence on the final metallurgical characteristics of the coated article, while of course the extent to which the silicon constituent of the coating is alloyed with or included in the base metal, has its own metallurgical effect on the final properties of the finished object «

For example, it has been found to be generally spoken an increase in the proportion of aluminum in the finished diffusion coating the oxidation resistance of the finished coating increases, but also increases the fragility or the ductility of the in a similar manner, it was observed that that the relative quantity of the three components of the overlap is determined apparently generally is a function of the temperature at which the application operation is carried out, at least one given proportions of the three ingredients in the order pack as well as at lower temperatures that result in a lower one Diffusion of chrome into the surface to be treated «

In addition to the above illustrative examples can generally be noted that proportions of the three components Sufficient silicon, aluminum and chromium in one application pack

^: 909812/0625 BATH ORIGINAL

within, flar fol ^ anden an2iäli92rnd32i Beraielie are provided ι 15 to 30 % .! Chromium ,, 1 to 20 $> 4Xvm ± n ± vm and 0.5 to 13 % Silieiunu Aäiola. is. ouch notice that _f when the .G-asamthait. odsr sum, des- Silicium-Aluaiii3a.iHiii ^ Ciir »5ßa ~ Q ^r ®halt®s dar Paekusg; roughly 60% of the entire Paokung3iaatsrials..ubim) 3lir®it®t.,. »Ino tendency towards undesired sintering? the Paekungsboetandtaile. ^ ährs.nd. dor the level of success, and. iia. extreme. Fall, ® ®i: ns braueiafo & r © / o_d; er fosfriediganda

dar τ © τβ ekiedaman drvüneeä £ .tesx Slsansnt.® in packs, er-.dia.only; 5.%. Aar G-osamtaua..3s, ®: from the. rising

S'ilisium, - Alt ^ iäiuia .und /.- Chrpsi-exhibits. «-. . . · ..--.

- "Of course · can ^v i3uie-rhalb ' ^: ä®'3 ^; -Be-roiSÄasg In ^ Olehem un -'- Nebeaeifi'skf® ¹ TSsSSiSiUSn -" are ¹ , ei.n® ^s "^ fai? I8s'e Impairment of effectiveness by a'rr @ de & t · '' werä &n'j'that' stan a 'practical''"* ^x ' ~ 'm8gl ± ch® $ -'hohan-Han ^ eaant'oil'"" dxai au diffusing Slomsnt® * '' in the -jobfspaGkung''vo3? a ± e3af, "-'in-the dia 'CJsganstänä © ain ^ spaekt should be» and s ^ rar natlirlioh. "'*" entapr- ech'end der OtHBq _t shape »volume 'totd. M © ug® dor © in ^ eset'-at'en objects in the""ratiosxas''"^' volume dsr Paokungs.bastasidteile »'Aush becomes dia' finished together - '* ⁷ "satsung? Odsr the tatsäcSalich®-Terlaältnis in d © ia arseugtaa tib ^ raxig * ^: ' • © nt3pr © oh.snd dan vorstaii ^ ndon Überiegungan aeirsrankssn ₉ but"bei'-apialswsisa lisf srt ο In © Paokung gfornäS dem yorstaiiandan Bsispisl a-tlbersug, -srorin di "components, approximately in the proportions" of 90 CJenTe-Teil® Aluainiuffl on 3 parts of chromium on 5 parts of silicon. ·. in the special alloys vorli'Qjjt ₉ irenn imibevor- -. ^; '"- sugtan temperature range from © tva 1000 to 11Ö.0? C (18ΟΟ to' 2100? P) norden is _β .... · - '. ..-? -., ■' - '■ - ■% ■ ;: ■ ".-; . - ..- · ■

d © r Srfiiidun ^ is alao a diffusion order in

HooHtimpair aturästähi © _t consisting of ®ia © r K®isfeinatiea From "'" Si "lioium _t

Aluminum and chrome under solehem! ^ Täd 'h%

. äuSera Auftragsshioht or 'iSahullung: sur Osydationsstei ^ ^ to chan, ness,''fctermes.toSvidars'tandsfMhi& ness tand other egg ^ eneohaf.'ten ainaa M "will stall @ ileis ad ar object is i consisting of a Aus§an | fSEiatarial or a Grundle ^ ierungf maaehinell ^ fire'ferti ^ t'jr.-geffokeen or "ff'e-" --formt --is _t the see in © r ^ üasohtsr ¥ & iga edit ader ^ ie lets »/ taa-die aot-wandise or ^ «^ dinsehta respective shape and the Qsgeastaadas or part au arreiohsn» ¥ ia drowned above and is srsisshtlish for the expert, the teachings of the SrfindunV are special

9098 12/0 62 5 ORIGINAL BATHROOM

^r copy

- 19 - H46117 '

applicable to heehniekelhaltige and high cobalt content · super alloy. conclusions, although the teachings of the invention increased strength against "thermal shock and oxidation also other materials, can provide especially primarily Else objects. For example, in a satisfactory Veise improved results by the invention to various kinds of stainless steels with high (s» B _a 35 * fa) ear and nickel content and caused in various austenitic steels with or without substantial proportions of nickel and ears, especially steels with a low carbon content sometimes it is found that the highest oxygen resistance can be achieved on such materials by cheaper means than the technique disclosed herein, so that although this technique gives work-wise enhanced properties on such other materials, it is economical before considerations know that the practical application of the technique disclosed here is to be retained primarily in the treatment of the high temperature superalloys for the purpose of achieving the high degree of oxidative and chemical resistance as indicated here "

what results from the above, the resulting sweeten Halides or other compounds of the object to be overlooked (which are developed in the package, as well as others not reactive products that are formed in the package and enter the formation of the desired diffusion tiber bug in the most distant end, all of which are adapted, absorbed or eliminated, Usage of some contamination of the pack is due to undesirable constituents and the formation of absolute equilibrium conditions, see below ▼ erseiden, us the reaction in question bsw. Reactions for the desired diffuse lens application in the surface of the overlooked The subject is wirkaas, swanglauflg το 11 at constant run su ·

If it is desired, as can often be the case, In particular, there are large numbers of them in daily use ▼ en objects that the same paekumg isser again for a carrion consecutive order work is to be reserved see difficulties arise "if non-reactive materials, which result from the order a tuf s, see in the 'a

9 09812/0625. _B AD ORIGINAL

COPY

accumulate or enrich © This is especially true »if a large Number of small parts in a production process are covered with «oll» and it is economically or for other reasons desired »a can * the order pairing, of course, refreshing the resulting to reuse exhausted materials instead of throwing away the whole pack after each order level and for the next load to prepare a completely new pack of objects »Venn in. such traps one the various by-products of the chemical Reactions from the previous order staggered in the pack could accumulate during the following loads Difficulties arise that the effectiveness of the pack eventually becomes becomes noticeably lower, even despite the renewal of such starting materials, which are actually incorporated into the pack »If so the amount or the proportion of the chemisch® reactions Materials created in the course of the order work in the If the pack enriches, it can become increasingly difficult to find the right one Reaction responsible for the job in more satisfactory Way to drive to completion if concentration of by-products of such a reaction is not necessary for the coating is productive, increases in the pack "

To explain such a situation, a special pronounced example to be noticed in the case where it is desired is a diffusion coating of chrome and aluminum in the surface of a metal object «. As a result of the one or others that take place in such a diffusion contract chemical reactions will apparently have a significant amount of chromium aluminide in the pack in addition to that amount of the original Chromium and aluminum which actually diffuses into the desired coating o apart from the fact that a ' such production of a chromaluminide which is not part of the Coating represents a waste of active and expensive packaging components means, the continued accumulation or increase in the concentration of ghromalumlnide in the pack, their Markedly decrease effectiveness for subsequent reuse, and either because one for the flow of diffusing materials Desired space is occupied or because it is according to the law of mass action. the desired diffusion reactions becomes more and more difficult to bring to full expiration in order to be more satisfactory \ 'λ. 9 0 9 8 1 2/0 6 2 5.BAD ORIGINAL

- 2f -

Show the diffused coating in the surface of the. to create a covering object »

According to the invention, however, measures and materials for the regeneration of such are provided for poor diffusion coating operations Application packs intended for repeated subsequent use, making the product unusable and unreactive chemical reactions that arise in it during a coating process are broken down in the pack into their respective useful constituents by the coatings of a subsequent Application process provided and or · or switched off or regenerated in order to avoid the undesired increase in concentration of non-productive accruing materials in the pack avoid. that made during each subsequent mission action The invention will encompass the use of a for this purpose Material, such as ammonium fluoride or ammonium lumbar fluoride, as at least a part of the protective material part in the pack, in order to obtain the desired substances in the subsequent application processes to split up chemical reactions that occur during previous order measures with the same order pairing

As can now be understood, there are a multitude

Halogen-supplying substances with which satisfactory results in diffusion deposition processes of the type in which the invention relates, can be achieved »Thus, various halides give satisfactory results, and in some cases elemental iodine is sufficient or even will be used for some application packages preferred * Of course, the natural state of elemental bromine, chlorine and fluorine is not suitable for immediate use an impregnation process with dry packing, as shown here »Various metal ions have also been suggested for such · halide substances» mentioned Jmamoni nmion in. Many cases are preferred »because of it presumably from the enclosed pack "results in the desired reducing atmosphere, which can be derived from it during the coating process" receives «although in some cases where in the material of the coating ·» and / or the metal object to be coated is not a nitrogen-free and hydrogen-free atmosphere. the order history should be maintained, an ammonium is not preferred

909812/0625 BADOR ₁ GiNAL

With many such application measures, the choice of a particular halogen or halide material cannot be of decisive technical importance, whether for one reason or another the pack is intended for a single application and should not be used repeatedly, or because the application process in question does not provide an undesirable «or useless intermediate product or derglo» as stated above, or for any other reason the more useful ammonium iodide "iodine or other halides or" their combinations are achieved "apart of course from the fact that the inconvenience associated with the use of ammonium fluoride in such processes, especially in view of the high temperatures at which they are usually carried out, it can make it appear advised "that other halides or halogen materials aiu prefer _r if you just emanates from the standpoint of operational borrowed <expediency"

Xn such cases jed®, ck _r as present counter, if the relevant job to be performed operation is positively connected to the tendency or ability during each application process in the package, zp a worthless or non-productive by-product. produce, which makes regeneration difficult or disabled for a subsequent application process the same package, satisfactory results in accordance with DMR invention have been achieved by the fact that, using as .. all or least significant part 4.9m halogen-providing component DMR pack active halides, such Ammoniurafluorid or Ammonium bifluoride, provides *.

As mentioned above, viewing is a diffusion deposition operation in which both chromium and aluminum are constituent parts of the coating is to be diffused into the surface of a metal object, wii associated with the formation of chremaluminide in substantial proportions, which on the one hand is part of the in the. ge ~ desired order to be diffused packing originally added Ohreas and aluminum consumed and on the other hand remains in the pack »without being diffused into the order amf the object» u are · In one such case it was found that there were difficulties with

^; '- ^i>; '-909-8 1 2 / 0-625. ■ BADORiGINAL

the reuse of the same pack for a subsequent order « operation with a subsequent loading of objects to be coated »also, separates exhausted · chromium, aluminum and halide in the pack are refreshed again ·

Venn However, according to the invention, ammonium fluoride or ammonium bifluoride is used in the package at least in their subsequent reuse as a source of vaporizable halogen, seem these compounds or their decomposition products such unwanted and non-productive by-products, such as "B _v Ghromaluminid to attack and break down and the ingredients productive or useful for diffusion into the surface of the objects to be coated in the reused package "in contrast, it has been found that other halides and even elemental iodine do not have this reactive desirable effect during the reuse and regeneration of a used application package"

As can be seen from the discussion above, such disruption of non-productive or intermediate products, as they arise from the previous coating processes, the multiple advantage that from the pack excessive accumulations a by-product of the chemical reactions, which may affect either the efficiency of the packing or the ease with which the desired reaction providing the coating up can be driven to completeness, adversely affect can, while the largest possible proportion of the chromium and aluminum metals, which are added to the packing to produce the coating, is used for increased efficiency, instead of worthless and discarded chromium aluminide being formed · This application pack can therefore be used repeatedly are regenerated according to the invention and also provides an increased overall yield of the added application materials It goes without saying, of course, that a certain proportion of the coating, metals and also the halides after each repeated use the, pack must be supplemented »

Merely to explain one embodiment of the Process according to the invention is given as follows: "Hehrere Inlet stator blades for a gas turbine engine were made from a

9 0 9812/0625 _B AD

Cast alloy consisting of approximately 55% cobalt, 24.5 # chromium, 10.5 $ »nickel, 9.5% (715%?) Tungsten, and 0.5% carbon. After casting, these wings are embedded in a coating pack of about 59.75% alumina as inert filler, 30% chromium metal, 8 ° fa aluminum metal and 2% silicic acid "All of these materials should be diffused into the wings as the silicon-chromium-aluminum-order be ₀ in the package also 0.25% 'Ammonlumbifluorid was introduced, and the application operation was performed in the übliohen Magi by included the package in an iron muffle and the sealed muffle 4 to 20 hours to temperatures of about 1000 to 1200 ° C (18ÖO to 2100 ° F) heated to produce the desired job »

After cooling, the muffle was opened and the coated wings removed for use. A subsequent insert of the same wings was then placed in the package, along with a supplement of chromium, aluminum and silicon as required (depending, of course, on the thickness of the The order required for the wings and in the relative proportion of the coating surface to the total amount of the package component © UPS ₁ ), A following operation was carried out with satisfactory results in approximately the same period of time, at the same temperatures and with approximately the same yield of materials that were in the surface of the Metal objects had penetrated. It was also found that if ammonium iodide was used instead of ammonium bifluoride, reuse of the packing would either be impossible or require a much longer time for the heat treatment with a considerably lower material yield, and that in the experiment w repeated repeated use of the pack despite refreshing the pack with new amounts of material to form the coating and halogen exciter, the pack would quickly come to a point where no more diffusion order can actually be achieved. "

As further examples of the method of an application operation according to the invention, the following compositions of various application pairs are given to which the Teachings of the invention are applicable. Look up for the parts the weight J

■: ■ "■■.; .. ■" BAD ORfGlNAL

. * .-. ■ 909812/0625

Example I.

60 parts alumina 30 parts chromium 8 parts of aluminite

2 part · silicon / k part ammonium bifluoride

Example II

60 parts alumina 30 parts chromium 8 parts aluminum

2 parts silicon 1/3 part ammonium fluoride

Example III

60 parts alumina 31 parts chrome 8 parts aluminum

1 part silicon

iA part ammonium bifluoride

Example V

65 parts alumina 30 parts chromium 3 parts silicon

2 parts aluminum

l / k part of ammonium bifluoride

Example VII

70 parts alumina 20 parts chromium 5 parts aluminum

5 parts silicon 1/2 part ammonium bifluoride

Example IV

65 parts alumina 31 parts chromium 8 parts aluminum

1 part silicon 1/3 part ammonium fluoride

VI

65 parts alumina 30 parts chromium 3 parts silicon

2 parts aluminum 1/3 part ammonium fluoride

Example VIII

70 parts alumina 20 parts chromium 5 parts aluminum

5 parts silicon 1/3 part ammonium fluoride

For further explanation of order packs that are useful in connection with the invention and in which the cation of the fluoride or bifluoride regenerator is different rom Ammonium is (as is desirable in certain coating applications Although the ammonium cation is useful because it itself produces a reducing atmosphere, the following can be be noticed 1

90 9812/0 6 25

BAD ORiGiNAl

1446 -1..T7

BeJ ₁ SpJ ₁ al IX

60 parts alumina 30 parts chrome 8 parts aluminum

2 parts © silicon 0.1 part Aimaonium bifluorid. 0.3 part chromofluoride

6® part® 3 © parts 8 T © ± X © AlumAsium

2 Taue _{Silicium ® 9} 15 part isanoniumfXuorid © ₉ 3 feil

the vorst © bands -Angalben, wstr & em daim different® usable application paokungon achieves ₈ sait demon increased results- · under. Use of a fluoride instead of another halide as Hal © ff @ 2ikomp © Eient® f © stgest © llt are fcosinta «Solen® t®n Br> @ 9bnis8 @ are particularly special .d © s ¥ ia <i © rg: # feraTuiQii3 τοη DiffuasiuasataftragpasktiKifeai to notice, in which wÄferend a © «first heating®- © d ©! ⁵ 2 & £ ft »ionsau: ftragv @ veanees the components in <ä®r Fa @ kisn ^ sw Bilduiia.g · certain iθrtuigen, ^ iθ -CUiromaliaminidj n® ± Qmn kdasiosi» This applies inabesonder® in cases fro di® packing separate ®d®r s @ nsti ^ e sources at Ohrora and = aluminum for d © n Di ^ jTuaiona order? deXt "WL" v can a © der Falfen der Brnitzun ^ buckets'. soXehen Fa @ k? mgiselbet trmnn di @ su covering @ e ^ arises therein are eat-cold "in the formation or association of carbon and aluminum into an intermetallic substance, like ohromaluminide, there are other halides than the flu @ ri & wid®S ⁵ StaadafMhigr is “so de, f3 How the use of a, solehon pack ± zi olmsm in the © hXiessenden work step can require a complete refreshment of @ hT @ m ™ * and aluminum _sources} although these materials are in <&&%> Faekiang from the previous order process in d "are present r interraetalXieshen bound form, the AE® the <oh.praktisch inert to an excitation or diffusion dureh the Hal @ (ge" idträger _s is separated about this "other than fluoride 1st" Bie yexvendung a fluorides as Halogenidträger or pathogen, on the other hand, sees inter-metallic substances, vle € & ufom & lumini <d _s the "iela in? a @ ktang forms in a previous order operation & aufaiaep lten and raaohen brauohbar mm for the Siffusionsauftrag, vodurch the utilization efficiency of the treatment materials and ¥ iedergebrauoh each on is increased wear package»

9098T2 / 0625

'. BADORiG (NAL

Of course, the above description is for the purpose of
Explanation and numerous modifications with regard to the conditions, proportions and particularly indicated constituent parts can be made without departing from the essence of the invention.

909 812/0 625

BATH ORIGINAL

Claims (1)

P at ® η ta ns ρ r Ü β h. β-. Method for generating a diffusion order made of metal itif the surface of a base metal roa high temperature resistance properties, daduroh characterized, that the alloy base metal is in a fusion build-up pairing embeds »the one source for an ear metal» an aluminum metal and silicon as well as a source of evaporable Halogen as a carrier for the chromium, aluminum and silicon in the Application of the diffusion oil into the surface of the base metal contains, '? and the örundlegisrraig · in this * P & ekung under application of chrome, aluminum and silicon dioxide together heated into the surface of the object » 2 · Method according to claim 1 »characterized * that the base metal has a substantial proportion of nickel, cobalt and contains iron and the heating in the pack to «ins Tem6 temperature in the CtreSenordntmg "* ®n at least about 900 (1650 ° P) takes place · 3 »© method of claim 1 of 2, characterized in that the package includes a _r aineralisehen inert filler, 4, method according to one of claims 1 to 3, characterized in ₉ that chromium, aluminum and silicon are present in the packing in amounts by weight of about 13 to 50% chromium, 1 to 20 % aluminum and 0.5 to 15 % silicon «, So method according to claim 3 © of 4, characterized in that the amount of chromium, aluminum and silver in the pack is about 3 to 60 $ 6, Metallgenstfind from a base alloy v @ n high temperature resistance, against long-term effects an oxidizing and corrosive atmosphere at high temperature and against Wäxraestoü & idex'standable, characterized by a cover made of an outer bluff application made of ßhrom, Aluminum and silicon « 9098 1270625 - '-. . ^v BAD GRIQiMAL 7. The object according to claim 6 »characterized in that the base alloy contains a considerable amount of nickel, cobalt and / or bison. 8, article according to claim 6 or 7 »characterized in that the outer diffusion contract about 90 percent by _e - contains% aluminum, 5% chromium and 5% silicon" 9 · Object according to one of claims 5 to 8, characterized characterized in that the diffusion layer has a thickness of about 0.025 to 0.05 mm (0.001 to 0.002 inches) " 10 * method according to one of claims 1 to 5 «thereby characterized in that the same pack is used repeatedly and at least one fluoride for at least the second use as at least one part of the vaporizable halogen component contains " 11 · The method according to claim 10, characterized in that the pack with the object embedded therein is heated to a * L · temperature substantially above the evaporation temperature of the fluoride « 12. The method according to claim 10 or 11, characterized in that that in the pack the vaporizable fluoride with the in remaining stable metal components remaining in the pack from previous use stages are converted into a form, which is able to participate in the diffusion order in the following order level. 13 · Method according to one of claims 3 to 5 and 10 to 12, characterized in that the mineral filler is present in the pack in a predominant proportion « 9098 12/062 5 ORIGINAL BATHROOM