EP2451987A1

EP2451987A1 - Iron-based spray material, method for producing a spray material, thermal spray layer, and spraying method

Info

Publication number: EP2451987A1
Application number: EP09780227A
Authority: EP
Inventors: Gérard BARBEZAT; Peter Ernst
Original assignee: Sulzer Metco AG
Current assignee: Oerlikon Metco AG
Priority date: 2009-07-07
Filing date: 2009-07-07
Publication date: 2012-05-16
Also published as: CA2767374A1; KR20120030528A; CN102471861A; US20130005618A1; AU2009349357A1; WO2011003439A1

Abstract

The invention relates to an iron-based spray material for thermally coating a substrate, in particular for thermally coating a running surface of a cylinder of a reciprocating internal combustion engine, wherein the spray material comprises FeTiO₃ as a base material. According to the invention, the spray material comprises at least one first solid lubricant made of a sulfide and a second solid lubricant made of a fluoride. The invention further relates to a method for producing a spray material, to a spray wire, in particular to a spray filler wire for use in a thermal wire spraying method, to an iron-based thermal spray layer, in particular for a running surface of a cylinder of a reciprocating internal combustion engine, to a spraying method for producing a thermal spray layer, to the use of a powder material and to a spray wire to produce a thermal spray layer.

Description

Iron-based spray material and method of making a

Spray material, as well as thermal spray coating and spraying

The invention relates to an iron-based spray material for the thermal coating of a substrate, in particular for the thermal coating of a tread of a cylinder of a reciprocating internal combustion engine, a method for producing a spray material, a spray wire, in particular spray filler wire for use in a thermal

A wire spraying method comprising an iron-based sprayed material, an iron-based thermal sprayed layer for a substrate, in particular for a tread of a cylinder of a reciprocating internal combustion engine, a spraying method for producing a thermal sprayed layer, and the use of a powdered material and a sprayed wire for producing a thermal sprayed layer according to the preamble of independent claim of the respective category.

Thermal spray applied coatings have long been known for a variety of applications. For example, surfaces of oil-lubricated cylinder liners in vehicle engines have been coated for some time by, among other things, plasma spraying, the film being primarily characterized by the coefficient of friction between Piston rings and cylinder wall is effective, significantly reduced, whereby the wear of piston rings and cylinder is significantly reduced, which leads to an increase in the running performance of the engine, an extension of the maintenance intervals, for example when changing oil and not least to a significant increase in engine performance. This is going through

achieved different measures. For example, such layers for oil lubricated internal combustion engines may contain deposits of dry lubricants in a base matrix, wherein in the

Base matrix additionally pores of predeterminable size can be provided, which act as oil pockets and thus together with the relatively soft embedded dry lubricants the friction between

Reduce piston rings and cylinder wall significantly. The basic matrix itself, which in particular contains the dry lubricants and the pores among other constituents, is composed of a hard matrix material which guarantees a long service life of the cylinder surfaces and piston rings. Such a modern high-performance cylinder running surface is described in detail in EP 1 340 834, for example.

Other typical applications for thermal spraying surfaces include coating turbine parts with anti-wear and thermal barrier coatings, components lubricated by oil-lubricated bearings, e.g. the coating of crank bearings or other workpieces subjected to particular physical, chemical or thermal stresses. Depending on the purpose of the coating, very specific materials are used, usually in the form of wettable powders or injection-molded wires, which have the necessary specific properties

Have properties and composition to generate the required properties of the surface layer to be sprayed.

For larger production volumes, the powder material price plays a decisive role in terms of the cost effectiveness of the coating, in particular in the coating of cylinder surfaces by means of the Plasma spraying process APS, especially in the case of coating of larger engines (truck diesel, for example).

The manufacturing costs of the powder depend on the one hand

Raw material prices and on the other hand, from the processing of the necessary to process the raw materials into a usable material, the

Implementation of the chosen method is suitable.

In the known atomizing of metallic materials (by means of gas or water), the energy costs can be influenced practically only by a better powder yield down. The specification of particle size distribution plays a crucial role here. Under ideal conditions, the production costs of metallic

Powders of a quality such as e.g. for internal coatings of cylinders for internal combustion engines, nowadays hardly lower under atomization at less than 10 US $ per kg. It is therefore to be expected that there are certain limits to further cost reduction.

On the other hand, the performance requirements of

Spray materials with time even bigger. In particular, the tribological properties of the coatings at elevated temperatures are becoming increasingly important because the effect of the lubricants with increasing

Wall temperature decreases significantly. Tribological solutions that are applicable up to a wall temperature of 350 ⁰ C, are in principle possible. The anti-scuffing properties of the coating materials play a decisive role here.

As a favorable manufacturing method of powders for thermal spraying generally applies the grinding and sieving, even in the case of larger quantities of ceramic spray materials of metallic oxides. In the case of certain materials, minerals in the powder can be added without additional

Melts are processed. A potential material for cylinder surfaces has previously been the iron titanate FeTiO3, which is also known as ilmenite. Ilmenite is formed from approximately 53% OO ₂ and 47% FeO, and crystallizes in a hexagonal crystal system. The hardness of ilmenite crystals is approx. 650 HV, which means that values of 400 to 500HV are possible in the layers with optimized parameters.

Therefore, already in the UA 74 987 an ilmenite spray material for the formation of corrosion-resistant coatings by means of thermal

Spraying proposed. In WO 2004/106711 beat the

Applicant Ilmenit, partly in combination with other metal-ceramic materials and / or oxides as a spray material for coating cylinder surfaces of turbocharged engines before. However, these coatings are not designed for the increasing tribological requirements at high or strongly fluctuating temperature loads, but improve mainly the hardness or corrosion resistance of the coated surfaces.

The object of the invention is, therefore, a new spray material in the form of a powder material or in the form of a sprayed wire, in particular

To provide Spritzfülldraht for thermal coating of a substrate, which can be produced on the one hand much cheaper than the known spray materials and thus sprayed layers especially excellent tribological properties, simultaneously in different temperature ranges, so that the powder material especially for the formation of friction-optimized running surfaces on cylinders

Hubkolbenbrennkraftmaschine is suitable, which are operated even under changing load conditions. The surface layers formed with the spray material should also be sufficient

be corrosion resistant and have excellent hardness. Furthermore, it is an object of the invention to provide a method for producing a corresponding spray material, as well as a thermal spray coating, a spraying method for producing a thermal spray

Spray layer, and to propose the use of a powder material or a spray wire for producing a thermal sprayed layer.

The objects of the invention solving these objects are characterized by the features of the independent claim of the respective category

characterized.

The respective dependent claims relate to particular

advantageous embodiments of the invention.

The invention thus relates to an iron-based spray material for the thermal coating of a substrate, in particular for the thermal coating of a running surface of a cylinder

Reciprocating internal combustion engine, wherein the spray material FeTiOs as

Base material includes. According to the invention, the spray material comprises at least one first solid lubricant of a sulfide and a second solid lubricant of a fluoride.

By the present invention it can thus be demonstrated for the first time that sprayed materials based on iron titanate, ie based on the so-called ilmenite with the chemical formula FeTiOs, are particularly well suited for the thermal coating of internal combustion engine components, if the ilmenite contains at least one sulfide and one fluoride is added as a solid lubricant. The layers produced with it are characterized by an excellent resistance

Adhesive wear characterized. The addition of solid lubricants comprising at least a sulfide and a fluoride, but especially also In addition, a nitride, thereby allowing a significant in the operating state

Increase of the wall temperature of cylinder surfaces, so that the layers produced from a spray material according to the invention are also particularly well suited for use in adiabatic engines. By the simultaneous use of at least one sulfide and a fluoride in the spray material according to the invention, it is ensured that the layers sprayed with it in a different manner

Temperature regions each have comparable good tribological properties. The tribological efficiency of iron titanate FeTiO ₃ layers

(Ilmenite) is inventively by the targeted addition of

Solid lubricants significantly improved. The properties of this

Among other things, lubricants are based on the special crystal structure and the low propensity for chemical bonds or reactions with metallic and ceramic materials. The concrete class

Solid lubricants according to the invention according to the expected

Temperature loads selected. In the case of Zylindehnnenbeschichtungen in internal combustion engines is advantageous to the highest

Wall temperature, for example in the contact zone

Cylinder surface / piston ring considered.

The solid lubricants sulfide-based, for example, M0S2 and / or WS2 can be used in an oxidizing atmosphere without any problems up to a temperature of 350 ⁰ C. In the case of shock loads in

However, internal combustion engines may have hot contact points, e.g.

form between the cylinder surface and piston rings, the local temperature can be significantly higher than 350 ⁰ C. Therefore, according to the present invention additionally at least one other type of solid lubricants is used, which has an increased temperature resistance and at the same time under the aggressive chemical conditions in Combustion chamber is chemically resistant and the adhesion and hardness of the coating also positively influenced.

In addition to the fluorides and solid lubricants based on nitrogen, for example, hexagonal BN or CrN are particularly advantageous in question, since they fulfill their functions as a solid lubricant up to highest temperatures of 950 ⁰ C, even under oxidizing conditions, such high temperatures, for example, in cylinders Of combustion engines often occur only locally.

In the special case of adiabatic diesel engines even higher local contact temperatures are to be expected. Certain

Fluorine-based solid lubricants are able to reliably ensure lubrication even under these critical conditions. For example, calcium fluoride _CaF2 and Bariumfluoride BaF ₂ can even ensure lubrication at locally occurring temperatures up to more than 1200 ⁰ C reliable. In this case, the eutectic formed from 62% by weight of BaF ₂ and 38% by weight of CaF ₂ has proven to be particularly effective, which ensures significantly improved lubrication already from 500 ° C.

It has been found that, depending on the particular type of engine, different compositions of iron titanate FeTiOs

(Ilmenite) and solid lubricant can be used advantageously. In the following Table 1, some typical examples are given by way of example. The information is valid above all for the internal coating of the cylinder surface of these engines.

Table 1: Typical application examples Combinations of

Solid lubricant additions in iron titanate layers FeTiOs.

When coating cylinder surfaces, e.g. With the help of an F-210 plasma torch, a powder yield of 60 to 70% can be expected. The specific gravity of the corresponding layers should be around 4 g / cm3.

Delivery rates up to 80g / min can be achieved, provided that

Powder delivery system is optimally designed. As a powder particle size, a distribution of 5 to 30 micrometers is advantageous. The maximal

Layer thickness is influenced by several factors (material substrates, Coating parameters, modulus of elasticity of the layers, etc.). On cast iron or steel substrates, the use of an intermediate layer is often not necessary, except in cases where severe corrosion is to be feared. For aluminum base alloys, for example, an intermediate layer of NiCr alloys and / or NiAl alloys is advantageous

exposed.

The thermally sprayed layers are advantageously post-processed in a manner known per se by diamond honing.

In a particularly preferred embodiment of a

According to the invention spray material, the volume fraction of sulfide is 0.1% to 15% by volume, preferably 1% to 6% by volume, the sulfide in a specific embodiment except for

Impurities only M0S2 and / or WS2 is.

The proportion by volume of fluoride can advantageously be from 0.05% to 20% by volume, preferably from 1% to 10% by volume, the fluoride in a specific embodiment, apart from impurities, being only CaF ₂ and / or BaF ₂ .

As already mentioned, CaF ₂ and BaF _{2 are} preferred, but not necessary, as eutectic. In a particularly preferred embodiment there is a

Spray material according to the invention except impurities only from a sulfide, a fluoride and the rest of FeTiOs as the base material.

In this case, the spray material to cover certain

Temperature loads additionally include a nitride as a solid lubricant, wherein the volume fraction of nitride is advantageously from 0.1% to 8% by volume, preferably from 1% to 5% by volume.

In this case, only hexagonal BN and / or CrN are particularly preferably used in a Sphtzwerstzoff according to the invention. In this case, in another variant, the spray material of the present invention, except impurities, also consist only of a nitride, a sulfide, a fluoride, and the remainder of FeTiO ₃ as the base material.

If the inventive spray material as a powder material for

When used in a thermal spraying process, a particle size distribution of the powder material is preferably between 2 μm and 60 μm, in particular between 5 μm and 40 μm.

To produce a spray material according to the present invention, the base material FeTiO _{3 is} prepared by grinding and / or sieving in a conventional manner from ilmenite, wherein the base material FeTiO _{3 can also be} remelted before grinding and / or screening first.

In a preferred embodiment of a production method according to the invention, at least one of the solid lubricants is formed in the form of solid lubricant particles and agglomerated by spray-drying and / or cladding with particles of the FeTiO ₃ base material.

The invention also relates to a spray wire, in particular

A spray-fill wire for use in a thermal wire spraying process comprising a spray material of the invention.

Furthermore, the invention relates to a thermal spray coating

Iron base for a substrate, in particular for a running surface of a cylinder of a reciprocating internal combustion engine, wherein the thermal spray coating comprises FeTiO ₃ as the base material. According to the invention, the thermal spray coating comprises at least a first solid lubricant of a sulfide and a second solid lubricant of a fluoride. Preferably, in a thermal spray coating of the present invention, the volume fraction of sulfide 0.1% to 15% by volume, preferably 1% to 6% by volume, in particular, the sulfide can be only MoS ₂ and / or WS ₂ to impurities , In a further embodiment, the volume fraction of fluoride in the thermal spray layer 0.05% to 20% by volume, preferably 1% to 10% by volume, preferably, but not necessary, the fluoride except impurities only CaF ₂ and / or BaF ₂ and / or CaF ₂ and BaF ₂ may be present as eutectic.

In a specific embodiment, the thermal spray layer can consist of impurities only from a sulfide, a fluoride and the rest of FeTiO3 as the base material.

In a further embodiment, the inventive thermal spray layer may additionally comprise a nitride, wherein the

For example, the volume fraction of nitride may be 0.1% to 8% by volume, preferably 1% to 5% by volume, and / or in particular the nitride is only hexagonal BN and / or CrN.

In a particularly preferred embodiment, the thermal spray coating of the present invention consists of only a nitride, a sulfide, a fluoride, and the balance of FeTiOs as the base material except impurities.

The invention further relates to a spraying method for producing a thermal sprayed layer according to the present invention, wherein the spraying method is a thermal spraying method, in particular a

Plasma spraying is.

In another embodiment, the thermal spraying method may also be a flame spraying method, an HVOF spraying method, in particular a powder spraying method or a wire spraying method, or another conventional thermal spraying method.

Moreover, the invention also relates to the use of a

Injection powder or a sprayed wire of a spray material of the invention for producing a novel thermal spray coating. In summary, it can be stated that iron titanate FeTiOs, which consists of about 53% by weight of O2 and 47% of FeO and crystallizes in a hexagonal crystal system, was known per se for use on cylinder surfaces of internal combustion engines in the prior art because of its tribological properties ,

Today, around 5,000 metric tons of llmenite are processed every year worldwide, especially for the production of color pigments from titanium oxides and the production of metallic titanium. The main deposits are located in Australia, Canada, South Africa, China, Norway, are still used to major deposits in Madagascar and

Mozambique.

At the end of 2008, the price of ilmenite minerals was $ 120 per metric ton. During further processing into sprayable powder (washing, grinding and sieving) only relatively low additional costs are to be expected, so that currently production costs of approximately US $ 5 per kg can be expected, plus the costs for the solid lubricants.

By the present invention, however, could be shown for the first time that with the raw material mineral llmenite for the simple and economic

Production of an iron titanate spray powder is an extremely suitable raw material available. The addition of solid lubricants such as nitrides (hexagonal BN, CrN), sulfides (MoS2, WS2), fluorides (CaF2, BaF2) or suitable combinations thereof, allow for increased wall temperatures of the cylinders of internal combustion engines. Thus, for the first time, the

Requirements for the construction and safe operation of adiabatic engines even under extreme temperature conditions realized.

Claims

claims

1. Iron-based spray material for thermal coating of a

A substrate, in particular for the thermal coating of a running surface of a cylinder of a reciprocating internal combustion engine, wherein the

Spray material FeTiO ₃ as the base material comprises, thereby

characterized in that the spray material comprises at least a first solid lubricant of a sulfide and a second solid lubricant of a fluoride.

2. Spray material according to claim 1, wherein the volume fraction of sulfide is 0.1% to 15% by volume, preferably 1% to 6% by volume.

3. Spray material according to one of claims 1 or 2, wherein the sulfide is only M0S2 and / or WS2 to impurities.

4. Spray material according to one of the preceding claims, wherein the volume fraction of fluoride from 0.05% to 20% by volume, preferably 1% to 10% by volume.

5. Spray material according to one of the preceding claims, wherein the fluoride is only CaF ₂ and / or BaF ₂ except impurities.

6. Spray material according to claim 5, wherein CaF ₂ and BaF ₂ are present as eutectic.

7. spray material according to any one of the preceding claims, wherein the spray material except for impurities consists only of a sulfide, a fluoride and the balance of FeTiO ₃ as the base material.

8. spray material according to one of claims 1 to 6, wherein the

Spray material additionally comprises a nitride.

9. spray material according to claim 8, wherein the volume fraction of nitride is 0.1% to 8% by volume, preferably 1% to 5% by volume.

10. Spray material according to one of claims 8 or 9, wherein the nitride is only hexagonal BN and / or CrN.

1 1. Spray material according to one of claims 8 to 10, wherein the

Spray material except impurities consists only of a nitride, a sulfide, a fluoride, and the rest of FeTiOs as the base material.

12. Spray material according to one of the preceding claims, wherein the spray material is a powder material having a particle size distribution between 2 microns and 60 microns, preferably between 5 microns and 40 microns.

13. Spray material according to one of the preceding claims, wherein the spray material is a spray powder for thermal spraying.

14. A method for producing a spray material according to one of

preceding claims, wherein the base material FeTiOs is prepared by grinding and / or sieving from ilmenite.

15. The method of claim 14, wherein the base material FeTiOs is first remelted before grinding and / or screening.

16. The method according to any one of claims 14 or 15, wherein at least one of the solid lubricants is in the form of solid lubricant particles and by spray drying and / or cladding with particles of the

Base material FeTiOs is agglomerated.

17. spray wire for use in a thermal wire spraying process comprising a spray material according to any one of claims 1 to 13.

18. An iron-based thermal spray coating for a substrate, in particular for a running surface of a cylinder of a reciprocating internal combustion engine, the thermal spray coating comprising FeTiO ₃ as the base material, characterized in that the thermal spray coating comprising at least a first solid lubricant of a sulfide and a second solid lubricant of a fluoride.

19. A thermal spray coating according to claim 18, wherein the volume fraction of sulfide is 0.1% to 15% by volume, preferably 1% to 6% by volume.

20. A thermal spray coating according to any one of claims 18 or 19, wherein the sulfide is only M0S2 and / or WS2, except for impurities.

21. A thermal spray coating according to any one of claims 18 to 20, wherein the volume fraction of fluoride 0.05% to 20% by volume, preferably 1% to 10% by volume.

22. Thermal spray coating according to one of claims 18 to 21, wherein the fluoride is only CaF ₂ and / or BaF ₂ except for impurities.

23. A thermal spray coating according to claim 22, wherein CaF ₂ and BaF ₂ are present as eutectic.

24. A thermal spray coating according to any one of claims 18 to 23, wherein the thermal spray coating consists of impurities only from a sulfide, a fluoride and the balance of FeTiOs as the base material.

25. The thermal spray coating of claim 18, wherein the thermal spray coating additionally comprises a nitride.

26. The thermal spray coating according to claim 25, wherein the volume fraction of nitride is 0.1% to 8% by volume, preferably 1% to 5% by volume.

27. A thermal spray coating according to any one of claims 25 or 26, wherein the nitride is only hexagonal BN and / or CrN.

28. A thermal spray coating according to any one of claims 25 to 27, wherein the thermal spray coating except for impurities only from a nitride, a sulfide, a fluoride, and the balance of FeTiO ₃ as the base material.

29. Spray process for producing a thermal sprayed layer after

one of claims 18 to 28, wherein the spraying method

thermal spraying is.

30. Spray method according to claim 29, wherein the thermal

Spray method is a plasma spray method.

The spraying method according to claim 29, wherein the thermal spraying method is a flame spraying method.

32. Spray method according to one of claims 29 to 31, wherein the

Spray method is a powder injection method or a wire injection method.

33. Use of a spray powder from a spray material according to one of claims 1 to 13 for the production of a thermal spray coating according to one of claims 18 to 28.

34. Use of a spray wire according to claim 17 for the production of a thermal spray coating according to one of claims 18 to 28.