DE2455529A1 - GALVANIC GENERATION OF THE RUNNING SURFACE OF A ROTARY LISTON COMBUSTION MACHINE - Google Patents

Description

Patent attorneys

Dipl. Ing. H. Hauck

. DIpT. Phys. VV. Schmitz

Dipl. Inn. E. Graaifs

Dipl. Ing. W. Place of residence

Dipl. Phys. W. Carstens

2 Hamburg 36

Neuer Wall 41

Hamburg, November 22nd

Galvanic generation of the running surface of a rotary piston internal combustion engine

The invention relates to both a method and certain step sequences in electroplating for the galvanic production of a wear-resistant running surface in the aluminum housing of rotary piston internal combustion engines, in particular the galvanic production of the epitrochoid running surface of the aluminum housing of the internal combustion engine of the Wankel type. In particular, the method relates to galvanic production of the tread by electroplating a Series of 'linings on a core, which for the rotary piston internal combustion engine of the Wankel type has the epitrodfcide shape and size of the tread, and then the aluminum housing pours against the last galvanic coating and the housing with the attached galvanic coatings, which the or the Coverings included, removed.

The method currently used to achieve a wear-resistant Surface for the epitrochoid tread in the

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Aluminum housing of the rotary piston internal combustion engine of the Wankel type consists in that the aluminum housing is attached directly to the core or to a porous, injection-molded, on the core Iron application and then a thick nickel coating, which contains deposited, fine silicon carbide particles, on the epitrochoid running surface on the inside of the aluminum housing or a thick chrome coating on top of the iron application electroplated. Then the thick covering is processed to the exact size. These "processes require internal anodes for plating the tread and a lot of metal has to be discarded because a particularly thick coating, usually twice as much Final thickness, which must remain after machining and honing to the final size for the bore, must be deposited. Even the time it takes to clad the thick coating adds greatly to the cost.

In the method according to the invention, the core is clad instead of the inner running surface of the aluminum housing and is used of a nucleus of high precision workmanship and exact size is hardly, if at all, any workmanship of the epitrochoid Surface required. Therefore, thinner hardfacing can be used and little, if any, metal goes which, lost by editing.

To the successful technical use of the system in which the exterior of the core instead of the interior of the housing is made To enable aluminum alloy to be electroplated, it is necessary that (1) the coating be easily detached from the core can be 'and (2) the die-cast aluminum housing adheres well to the end coverings.

Using a largely machined, accurate core, there would be much less machining or grinding, if any required for a final, accurate surface with this method than the current method of plating the Interior of the housing made of aluminum alloy. The present one

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The process requires the electrodeposition of very thick coatings, approximately 0.381-0.508 mm (15 to 20 mils), in order to be secure be sure that enough coating (0.1016-0.1524mm, 4-6 mils) remains after grinding or machining, and that means one great economic loss. This costly procedure used to clad the interior of the aluminum housing becomes, results from the fact that .the covering'with increasing Thickness becomes less smooth, as well as from the fact that the Comparative distribution of the coating from acid baths (nickel and chromium) is bad, which leads to a non-uniform thickness of the coating on the epitrochoid surface. In which Method of plating the exterior of the core uses the first part of the pavement and it is as smooth as the core and as exactly in the dimensions as the core. Therefore, even if the core is not absolutely accurate in dimensions, this is what is needed The amount of machining or grinding is far less than the current process using the inside of the case is plated. In addition, the first deposit or the first deposits deposited on the core can be compared thin pads made of less hard material than the wear-resistant pads. These toppings can be easily edited or honed and could even be used as wear-in before the wear-resistant surface reaches will.

This type of flooring is illustrated in some of the examples below.

The process of electroplating the exterior of the core instead of the interior of the aluminum alloy housing also allows the use of a new wear-resistant lining, which is much less costly than the currently used thick nickel wear-resistant linings, which are about 2.5% by weight with deposited fine silicon carbide particles, or of thick chrome ("hard chrome"). The new wear-resistant covering for the rotary piston internal combustion engine of the Wankel type is in

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Example 1 described and ordered from electroplated iron containing 2.5% by weight and above co-deposited fine silicon carbide particles. It is possible to very warm (about 71-88 ⁰ C; about 160-190 ⁰ F) in the Eisenplattierungsbädern low pH (around 1) on vertical surfaces twice as much as the silicon carbide fine particles mitabzuscheiden in nickel plating baths. Since there is little or no machining or grinding of the hard, wear-resistant surface, the hardest wear-resistant coating possible can be used, i.e. iron or nickel coating or a combination of them with a higher percentage (up to 8% by weight) in the iron coating) on co-deposited silicon carbide particles. When plating the epitrochoid running surface on the inside of the aluminum alloy housing, it is too difficult to use a hot, low pH iron plating bath because the aluminum housing will be attacked in the areas which will not be plated.

In fact, more than one hard-wearing pad can be much lighter can be used when the core is plated instead of the interior of the aluminum alloy case, as in Examples 2 and 3 is set out.

example 1

A steel core with good surface finish and dimensions that match the desired dimensions of the epitrochoid tread are close to or equal to (approximately 24 * .13 cm for the longest Diameter of the epitrodDiden tread, about 17jÖ cm for the necked diameter and about 6.1 cm for width) is electroplated with the following series of coverings.

(1) A thin lead of about 0.0025 mni (0.1 mil) or less less is first plated onto the steel core by, for example, an acidic lead fluoborate bath, which is preferably one or more additives from the group of gelatine, naphthol,

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contains non-ionic wetting agent and lignin sulfonate. This can take 1 or 2 minutes (1 or 2 min.plate) be.

(2) This is followed by a copper coating, preferably made of a bare, acidic copper sulfate plating bath such as that described in U.S. Patents 2,707,166, 2,738,318, 3,288,690, and 3,328,273 is. The copper coating can be from about 0.0025 (0.1) to about 0.0051 mm (0.2 mil) in thickness.

(3) This is followed by an iron coating which contains co-deposited fine silicon carbide particles to about 2.5% by weight to about 8% by weight. The iron bath may mainly of iron (II) chloride, about 300 g / l be prepared with or without about 150g / l calcium chloride and bath temperature at pH of about 1 and from about 71 to 88 ⁰ C - work (160 190 ⁰ F) . The concentration of the silicon carbide powder can be about 25 to 150 g / l, which is dispersible in the bath by mechanical agitation. Instead of iron (II) chloride, the bath can mainly be made from iron (H) sulfate, which works as described above for the iron (II) chloride bath. Lower current densities are usually used for the ferrous sulfate bath compared to the chloride bath. However, the warm, low pH sulfate bath has the advantage that no corrosive hydrochloric acid vapors escape from the bath, as does the chloride bath.

The iron coating with the co-deposited silicon carbide particles Will be about 0.51 (2 mils) thick to as much as 0.254-mm thick (10 mils) or more deposited if desired. The last 0.025 mm (1 mil) or 0.051 mm (2 mils) of the thicker one Coatings can use coarser silicon carbide particles in a separate bath to remove a rough coating from in the iron coating to give firmly embedded silicon carbide particles.

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This rough covering supports the bond to the subsequent aluminum alloy housing, which is cast on this - ^ elag will. Instead of pouring the aluminum alloy directly onto this iron surface, a thin zinc coating is preferably used about 0.0025 (0.1 mil) to about 0.051 mm (2 mil) is plated on the iron surface and then the aluminum alloy potting step follows. The zinc coating can be deposited and supported on both a smooth and a rough iron coating to a large extent the binding of the aluminum to the iron covering. The zinc melts when the aluminum alloy metal is hot hits the zinc and most of the zinc goes into the aluminum alloy and some into the iron coating. This method allows the aluminum alloy to come into contact with iron coating which has no oxide coating because the iron surface was protected by the zinc coating.

The heat from the molten aluminum alloy causes the thin lead coating to melt against the steel core and it allows the covering with the attached aluminum housing to be removed from the core. The core can be hollow, i.e. in the shape of an epitrochoid bing, or can have holes for cooling purposes exhibit. Cooling the inside of the core (with cold water) causes contraction and can remove the plaque support with its attached housing.

The final zinc coating is preferably of great purity in order to help achieve the best bond between the aluminum and the final coating (s). On the other hand, it is best to use baths with inclusions, such as additives, for the first layer or layers against the core, in order to help achieve the poor adhesion necessary to separate it from the core. Lead with its low melting point (327 ^° C.) loses its adhesion to steel and the molten lead at these temperatures is practically insoluble in the copper which is plated on top of it. When cooling the core, for example by circulating water through

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a cylindrical cavity or an epitrochoid cavity or through holes in the interior of the core which supports itself As a result of the contraction, the separation from the core at the lead interface also occurs.

Example 2

It is the same way of working as in Example 1 with the difference that nickel coating with co-deposited fine silicon carbide particles up to the amount of about 2.5% by weight and higher instead of all of the iron coating with co-deposited silicon carbide particles or part of the iron covering is used.

The nickel coating with the co-deposited silicon carbide particles can be obtained from the acidic baths of the Watts type, types with a lot Ohlorid or a lot of bromide, or sulfamate or fluoborate deposited will. Since the acidic fluoborate type anode baskets made of titanium attacks, is the lluoborate type over the other types not preferred. The nickel baths can contain additives of class I, such as benzene or toluenesulfonamide, di-benzene or Di-toluenesulfonimide, o-benzoylsulfonimide (saccharin), benzene mono- or disulfonic acids, benzene and toluenesulfinic acids, Naphthalenesulfonic acids, allylsulfonic acids, o-sulfobenzaldehyde (or the sodium or potassium and similar salts of these various acids), sulfonimides and sulfinic acids, or the like Class I Compounds. These Class I compounds cause the incorporation of from about 0.01% to about 0.2% sulfur as sulfide in the nickel coating, which increases the hardness and tensile strength the nickel coating is greatly increased. Those for the purposes of the invention including the co-deposition of fine silicon carbide particles or other fine hard particles preferred compounds of Class I are the benzene or toluenesulfonamides, the di-benzene or di-toluene sulfonimides. These Class I compounds allow the maximum amount of co-deposition of fine particles such as silicon carbide for a given

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Concentration of dispersed fine particles in the nickel baths. The preferred concentration of silicon carbide particles is in the range of 25 to 150 g / l. The preferred method air agitation is used to disperse the particles in the nickel baths. Wetting agents such as sodium n-octyl sulfate can be used or sodium 2-ethyl-hexyl sulfate available in nickel baths be. They are normally used at concentrations of from about 0.1 to about 1 g / l.

With this method of plating the core, the nickel coating with the co-deposited silicon carbide particles in two or more steps are applied. For example, a thin, pure nickel coating of about 0.0127 mm (0.5 mil) applied to about 0.0254 mm (1 mil), then the nickel plating deposited with the mitabgeschiedeneη particles of silicon carbide will. In the method of the invention of plating the exterior of the core rather than the interior of the housing From aluminum alloy, a coarser grade of silicon carbide can be used instead of uniform, very fine ones Silicon carbide particles to be used when plating the interior of the aluminum case or the lining becomes impermissibly rough as the plating progresses. In the method of the invention, the first part of the pavement is the most important and it is smooth because plating starts against a smooth surface and continues plating the roughness that occurs with the larger silicon carbide particles to bond with the cast aluminum alloy conducive. The nickel coating can be made up of fine, uniform, finely ground silicon carbide particles for the first part of the Nickel coating are deposited, then the nickel coating with co-deposited silicon carbide particles from a nickel bath, which contains coarser silicon carbide particles dispersed in order to achieve a rough surface. The latter enables better adhesion to the aluminum alloy that is cast on it, with or without a zinc coating. The usage a thin, pure zinc coating of about 0.0025 mm (0.1 mils)

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up to 0.051 mm (2 mils) is preferred for best bond performance regardless of whether the rough nickel coating is used or not. The pure nickel coating, which is at the beginning of the nickel plating part the! sequence of deposits can be used, with the air movement switched off in the bath, which the Contains silicon carbide particles, or in a separate bath in which no particles or comparatively few particles are present.

The wear resistant lining can be made from a first nickel lining about 0.0254- (1 mil) to 0.076 mm (3 mils) thick, which contains co-deposited finely divided silicon carbide particles, followed by an iron coating of similar thickness, which contains co-deposited silicon carbide particles. Of the End zinc coating to achieve maximum adhesion of the aluminum housing is then deposited on the iron coating prior to the casting stage.

Example 3

It is the same way of working as in Example 1 with the difference that after the copper coating of stage (2) chrome coating for stage (3) instead of the iron coating with co-deposited silicon carbide particles being knocked down. The chrome could be directly on the copper coating or on a comparatively thin one Nickel or iron coating can be plated. The chrome can be from about 0.051 mm (2 mils) to about 0.254 mm (10 mils) be plated. In addition, by plating the outside of the core, the high-speed acid plating baths of the hexavalent Chromium, which use both sulfate and fluoride (or complex fluoride) catalysts, such as those in US-Ps 3 334 033, 2 78? 588 and 2,640,022. If the interior of the aluminum housing is to be chrome plated with a thick coating, it is generally preferred to use the standard "hard chrome" plating bath to use, which only uses the sulfate anion as a catalyst, because the fluoride-containing

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Anion possibly the aluminum in the areas which Does not get chrome plating, attacks unless special precautionary measures are taken.

After the chrome coating has been deposited, a nickel coating, for example from a Watts, chloride or sulfamate bath, can be applied the chromium are deposited after the chromium deposit is first a thin nickel electrode deposit at low pH (Wood's Nickel) to secure the bond to the chrome coating. The nickel coating can be up to 0.127 mm, for example (5 mils) thick if the chrome plating is approximately 0.051 mm (2 mils) is up to 0.152 mm (6 mils), or about 0.0254 mm (1 mil) to 0.102 mm (4 mils) when the ghrome is about 0.102 mm (4 mils) is to about 0.152 mm (6 mils). The nickel bath can also contain class I additives, which are listed in example 2 as well as silicon carbide particles deposited with it. After the nickel coating, a thin, preferably pure zinc coating is formed Applied before the casting stage of the aluminum alloy to ensure maximum adhesion. Instead of a nickel coating, which is applied to the chrome coating, iron coating can be applied with or without co-deposited silicon carbide particles as described above. The iron coating is then preferably given a thin zinc coating before the casting stage Aluminum. Even if it requires a further stage, it is actually also possible to coat the nickel with iron or vice versa or to be plated with cobalt and then with a thin, essentially zinc coating prior to the casting step of the aluminum alloy to plate. This also applies to example 1 and example 2. This is retained in the casting stage of the aluminum alloy Zinc with its excellent adhesion to nickel, iron, cobalt or their alloys not only "the purity of the surface of these latter coatings and their freedom from oxide, but also With the heat from the molten aluminum, the zinc will alloy itself with these lower metals and also alloy itself in more compatible Way with the molten aluminum.

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-11 Example 4

The surface of the steel core is first prepared as follows. The steel core is adhesively plated with nickel (about 0.0051 (0.2 mils) to 0.127 mm (5 mils)) simple Watts nickel bath or other acidic nickel baths, such as high chloride or sulfamate baths or from a semi-bright or bright nickel plating bath. A semi-bright or bright, even nickel coating is preferred. The nickel coating is used for maximum protection against corrosion of the core. The nickel coating is then rated at about 0.0000254 (0.001 mil) to about 0.0051 now (0.2 mil) chrome plated. The core can be chrome plated directly, but it is preferred to nickel plating first. It may also be desirable to have a copper base to use for the nickel or the chromium to support heat or cold transfer. The core with its chrome surface is now the finished core, ready for use in the plating sequences and final casting stages of the alloy, as described below.

The chrome-plated surface of the core is in that sense one of the It is possible to regard separation layers as it is possible, because of the great passivity of chrome plating, poor connection to chrome surfaces to achieve. The most important thing is to have poor chrome build-up adhesion, but without a blistered build-up. This can be achieved with the following clad metals, zinc, tin, nickel, cobalt, iron and their alloys, when acid plating baths of these metals under controlled Conditions are used. In the case of galvanizing, an acidic bath of pH about 2 to about 4, preferably about 2 to 3, is used; a tin (II) bath with a pH of about 0 to about 3 is used for tinning, and for nickel, cobalt, iron and their alloys a pH of about 1.5 Ms about 6 is preferred. These rubbers can range from momentary superficial plating to about 0.051 mm (2 mils) in thickness. For zinc and tin is the preferred thickness about 0.00254 mm (0.1 mil) or less

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niger, achieved in a plating time of about 1 to about 2 minutes. In the case of nickel, cobalt, iron and their alloys, coating even thicker than 0.0254 mm (1 mil) can be used directly on the chrome-plated core and in fact their wear-resistant coating with co-deposited hard particles can be used directly on the chrome coating with poor adhesion plated for separation. If the pH of the baths for plating these metals is well below a pH of about 1 to 1.5, the nickel, cobalt and iron deposits will adhere too tightly, indeed perfectly adhere, when the pH is around zero or below and especially if no film-forming additives, such as butynediol, are present in these baths. The baths can be acid sulfate, chloride, bromide, sulfamate, fluoborate, methanesulfonate, and other nickel plating salts or mixtures of these salts. In general, the nickel bath of the sulfamate type with its very low stress is preferred for use for the first coating against the chrome-plated core, the pH being controlled ^{around 4 and the bath temperature being controlled to 49 to 54 ° C.}

If the core is flat steel, then not only lead but also other low-melting metals and alloys can be plated directly on the core, followed by copper or brass from an alkaline bath or nickel from a neutral or nearly neutral or an alkaline bath to achieve separation from the core. For example, instead of a thin lead coating of about 0.00254 mm (0.1 mils) or even less on the core a thin cadmium coating (mp. 321 C ⁰⁾ are used. The heat from the step of pouring the molten aluminum causes the bond of the cadmium film to be broken, both by melting and by diffusion into an overlaid film such as copper or brass. Thin Zinnbelag (mp. 232 ⁰ C) can also be used with or instead of lead and cadmium. Zinc coating (m.p. 420 ⁰ C) is preferred over tin, lead or cadmium or their alloys because it

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is less expensive and more abundant than tin, and is far less toxic than lead and cadmium. For example, if a thin zinc coating is deposited on the core, followed by a thin copper or nickel coating, followed by the wear-resistant coatings already described, followed by a final zinc coating, then under the influence of the heat from the aluminum potting step, the thin one lying against the core becomes thin Alloy the zinc coating with the thin copper or nickel coating on top and lose its connection with the core. For this series of coverings, the chrome-plated core is preferred, especially when zinc is plated directly against it from an acidic (pH 3-4) zinc sulfate bath at room temperature.

The use of the chrome-plated core, on which a deposit of nickel, cobalt, iron or their alloys, but preferably nickel, is deposited in order to achieve the required poor adhesion to the chrome-plated core for the separation stage, offers the shortest sequence of deposits for the process the invention. For example, the chrome-plated core can be coated directly with nickel in a thickness of about 0.00254 to about 0.051 mm (0.1-2 mils) from a bare nickel sulfamate bath (with or without about 10 to 20 g / liter nickel chloride) with a pH of about 3, 5 "to 4.5 and a bath temperature of about 49 to 54 ° C (120-130 ⁰ F). The low stress nickel coating has poor connection with the chrome-plated core. It is preferred that no organic additives except After this first nickel deposit is deposited on the chromium with poor adhesion but without blistering, the core is transferred to an air-moving high-speed nickel plating bath containing about 50 to 150 g / l fine silicon carbide particles dispersed therein The preferred rapid bath for the deposition of this wear-resistant nickel film is the nickel sulfamate bath, although the high chloride or Watts nickel baths are also used n can. The maximum co-deposition of the fine silicon carbide particles on vertical

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Areas takes place at pH values of the bath of 4 to 5 · Also can in these baths the additives of class I for nickel, such as saccharin, benzene or toluene sulphide, o-sulfobenzaldehyde, benzene or naphthalenesulfonic acids etc. for hardening the nickel structure, which the co-deposited contains fine hard particles. It is important to keep tension in the nickel plating by using the above-mentioned voltage reducer is kept as low as possible. This is particularly important in Watts and in chloride-rich nickel baths. In the sulphamate bath can be a minimum the voltage reducer or none at all can be used. After depositing approximately 0.102 mm (4 mils) of the wear resistant Low stress nickel deposit, which contains about 2.5 to about 4 wt .-% co-deposited silicon carbide particles, A zinc coating of about 0.00254 to about 0.051 mm (0.1 to 2 mils) thick is used as the final coating prior to the potting step deposited the aluminum case.

Instead of the above wear-resistant coatings of nickel and iron or any combination of these coatings, it is possible to use chrome coatings to be used as the main wear-resistant lining. However, it is preferred because of the brittleness of the very hard; thick chrome deposits (hard chrome), the chromium deposit with one or more of the tough deposits of nickel, cobalt, iron or to use their alloys in about the same or greater strength than the chrome coating. This is necessary to prevent that one has a brittle, hard coating which lies against the comparatively soft surface of the aluminum housing.

The use of a chrome-plated core with a first layer of low-tension nickel, for example from a sulphamate bath, is an excellent method for the separation stage. The chrome-plated core is left clean and the separated surface is clean and has the exact surface quality of the chrome-plated core, which is bare

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or can be matted. To reuse the chrome-plated The core is either no cleaning or cathodic cleaning in an alkaline cleaning agent followed by rinsing is the only necessary step. Fresh, thin chrome plating The core only requires rinsing before the release liner is applied.

This method is consistently the method of plating nickel, cobalt, or iron or their alloys on one with passivated nickel plated core and then separating the nickel from nickel is superior. The nickel-plated core can be controlled by anodic alkaline cleaning or by immersion in weak chromic acid or chromates or by other, visible or invisible membranes, such as sulphide membranes, Copper skin (immersion copper skin), etc. are passivated.

The chrome-plated surface of the core is excellent as a passive surface and it can not only be used on steel and nickel-plated Steel, but can also be plated on cores made of Invar, Kovar or stainless steel. Still can be a stainless Steel surface or a similar passivated surface without the chrome coating can be used, albeit the latter surface is preferred.

In repeated experiments poorly adhering coating can be formed using a chromium-plated steel core, which is lower with nickel voltage from a Sulfamatnickelbad the pH of about 4 and the bath temperature is plated 4-9 54- ⁰ C, but are obtained consistently without blistering, even if it is exposed to high temperatures of 500 ⁰ G and above. The steel core was tubular and was adhesively plated with bare nickel, approximately 0.051 mm (2 mils) thick, before the approximately 0.00254 x 0.1 mil (0.1 mil) chrome plating was applied. It is important that the core after application of the zinc coating on the Endnickelbelag (or cobalt coating) with its pads to about 400 ⁰ C, or even above is preheated before the Vergießstufe the aluminum alloy is performed. This pre-heating stage allows

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maximum expansion of the core before the hot melted Aluminum surrounds the plated core surface. Then it is easy to cool after the resulting contraction of the Core to remove the housing with its now attached wear-resistant running surface from the surface of the chrome-plated core.

The use of an anti-friction material in the form of macroparticles, such as barium sulfate, strontium sulfate or mica for co-deposition with the nickel, cobalt or iron coating or their alloys has a distinct advantage in the method of the invention for two reasons. In the first Coating on the chrome-plated core, such as the low-voltage nickel coating from the sulfamate bath, allows its presence co-deposited fine barium sulfate particles up to the amount of about 1 to about 3 weight percent easier separation of the core. Caused in the wear-resistant lining alone or together with co-deposited fine silicon carbide particles it decreased friction against a frictional surface, like the seals used in whitewash engines. The concentration, those in nickel, cobalt or iron plating baths can be used dispersed, is about 20 to 150 g / l fine barium sulfate particles from about 0.1 to about 5 microns in size.

Another coating that can be used instead of zinc or zinc-rich alloys such as a galvanic coating of white or yellow copper to allow good adhesion of the aluminum alloy housing cast against the end coating of nickel, cobalt, iron or their alloys is a thin silver coating instead of the zinc coating for the final coating in front of the potting step of the aluminum housing. With silver, the coating can be preheated to higher temperatures (500-70O ⁰ C) before the aluminum is cast than with zinc coating. This allows less stress in the potting step which can produce an inferior bond. Silver plating gives much better results than copper plating for this purpose.

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In summary, the invention relates to a method for galvanic Generation of the epitrochoid running surface for the rotor of a rotary piston internal combustion engine. The method includes the electrodeposition of a series of coatings on a core of epitrochoid shape with a chrome surface and casting an aluminum alloy housing on the end covering. The sequence of coatings applied to the chrome-plated core includes (1) a first coating with poor adhesion, consisting mainly of winding, cobalt, iron or their alloys Group, (2) a wear-resistant lining and (3) an end lining to support good adhesion of the aluminum housing cast on it. These are the main levels. Intermediate stages may also be included, such as use of two or more wear-resistant pads in stage (2). Step (1) and step (2) can also be combined into one plating step will.

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Claims (13)

Claims 1. A method for forming a housing essentially made of aluminum for the running surface of a rotary piston internal combustion engine, characterized by the levels: (1) electrodeposition of a first layer on a core in the shape of the running surface of the rotor, the Core has an ear surface and the first deposited thereon Layer a metal from the group consisting mainly of nickel, cobalt, iron and their alloys and is separable from the core during subsequent stages, (2) galvanic deposition of a wear-resistant layer on this first layer, (3) then casting a housing essentially from aluminum (4) Separating the housing from the core with a chrome surface. 2. The method according to claim 1, characterized in that the core has the shape of the epitrochoid running surface of the rotary piston machine having. 3 · The method according to claim 1, characterized in that the Stages (1) and (2) are combined into one stage, the first being galvanically deposited on the core with a chrome surface Layer represents a wear-resistant covering, which can be separated from the core with a chrome surface, and selected from the group of nickel, cobalt, iron and their alloys as well as co-deposited fine, hard, non-metallic particles. 4. The method according to claim 3 »characterized in that the co-deposited fine, hard particles are silicon carbide. 5G9823 / Ö840 5- The method according to claim 1, characterized in that following step (2) a metallic layer on the wear-resistant layer to improve the adhesion of the aluminum casting formed on the previously formed wear-resistant visual layer will. 6. The method according to claim i, characterized in that. that the wear-resistant covering is Ghrom. 7. The method according to claim 5 · »characterized in that the metallic layer to improve the adhesion of the aluminum casting, an electrodeposited layer from the group Zinc, brass, Miekel, cobalt, iron and their alloys. 8. The method according to claim 6, characterized in that the chrome coating is further coated with a metal from the group Micke 1, cobalt, Iron and their alloys are plated. 9. The method according to claim 7s, characterized in that the Layer to improve the adhesion of the aluminum casting · is essentially zinc, which is deposited on a metal from the group Nickel, cobalt, iron and their alloys as well as brass are deposited is. Method according to claim 1, characterized in that the wear-resistant covering is essentially Uiekel covering, which about 2 to about 4 wt .- $> contains fine particles of silicon carbide. 11. The method according to claim 1, characterized in that the wear-resistant covering is essentially iron covering. Which contains about 2 to about 8 weight percent silicon carbide fine particles. 12. The method according to claim 1, characterized in that the first layer deposited in step (1), which is separable from the chrome-plated core, is deposited from an aqueous, acidic bath with a pH of about S ₁ ^ ffä & i &fa'a? ^ '. 509823/0840 13. The method according to claim 1, characterized in that the wear resistant coating is essentially nickel coating containing from about 1 to about 4 weight percent fine barium sulfate particles. 14-. Method according to claim 5i, characterized in that the metallic layer to improve the adhesion of the cast aluminum part, an electrodeposited layer of silver is. 609823/0840