EP2668308B1 - Wire feedstock for thermal spray ing a layer having perlitic, bainitic and martensitic phases - Google Patents

Description

The invention relates to a wire-shaped spray material, in particular for arc wire spraying, comprising essentially iron and a thermally sprayed layer which is deposited on a substrate.

For reasons of energy efficiency and emission reduction, the lowest possible friction and high abrasion and wear resistance are aimed at in the production of internal combustion engines. For this purpose, engine components, such as cylinder bores or their walls are provided with a tread layer or it liners are inserted into the cylinder bores, which are provided with a tread layer. The application of such tread layers mostly takes place by means of thermal spraying, for example electric arc wire spraying. In arc wire spraying, an electric arc is generated by applying a voltage between two wire-shaped spray materials. In this case, the wire tips melt and are conveyed, for example, by means of a nebulizer gas to the surface to be coated, for example, the cylinder wall, where they accumulate.

From the DE 103 08 563 B3 a cylinder liner for internal combustion engines is known, comprising a base body with a wear protection coating on the tread, based on a hard iron alloy with carbon and oxygen, wherein the wear protection layer martensitic Has phases and oxides and the wear protection layer in the arc-wire spraying method is applicable and the alloy of the coating has a carbon content of 0.05 to 3 wt .-%.

From the DE 10 2008 034 547 B3 For example, wire-formed spray material for a thermally sprayed iron-based layer having a bainitic martinsitic structure is known which has a carbon content of 0.23 wt.% to 0.4 wt.% and a chromium content of 0.75 wt.% to 0.95 wt .% and other alloying constituents.

From the DE 10 2008 034 549 B3 is a wire-formed spray material for a thermally sprayed iron-based layer with a pearlitic, bainitic, Martinsitischen structure known, which has a carbon content of 0.45 wt.% To 0.55 wt.% And a copper content of 0.25 wt.% To 0, 35 wt.% And other alloying constituents.

From the DE 10 2008 034 551 B3 For example, wire-formed spray material for a thermally sprayed iron-based layer having a bainitic martinsitic structure is known which has a carbon content of 0.35 wt.% to 0.55 wt.% and a copper content of 0.25 wt.% to 0.35 wt .% and other alloying constituents.

From the DE 10 2009 039 453 A1 or the DE 20 2009 001 002 U1 For example, a wire-shaped spray material for a thermally sprayed iron-based layer having a pearlitic, bainitic, martinsitic structure is known which has a carbon content of from 0.1% by weight to 0.28% by weight and a silicon content of from 0.05% by weight to zero , 3 wt.% And other alloying constituents.

From the US 5 592 927 A is wire-shaped spray material for a thermally sprayed iron-based layer known which has a carbon content of 0.04% by weight to 0.2% by weight, a silicon content of 0.025% by weight to 0.04% by weight, a manganese content of 0.04% by weight to 2% by weight, a Chromium content of 0.02% by weight to 2% by weight, a molybdenum content of 0.02% by weight to 2% by weight, a nickel content of 0.02% by weight to 4 and a copper content of 0.02% by weight. to 0.5 wt.% And other alloying ingredients.

It is an object of the invention to provide an inexpensive improved wire-shaped spray material, in particular for arc wire spraying. In determining the wire-shaped spray material, the spray properties of the wire-shaped spray material and the machinability of the spray layer are selectively influenced in addition to the layer properties.

It is a further object of the invention to present a dense, tribologically improved sprayed layer, which can be applied to a substrate in particular by arc wire spraying and can be processed well.

The object is achieved by a wire-shaped spray material with the features of claim 1.

Advantageous developments are the subject of the dependent claims.

An inventive wire-shaped spray material, in particular for arc wire spraying, essentially comprises iron. The spray material is formed at least with carbon as a micro-alloy in such a way that at least pearlite and bainite are formed upon solidification of the spray material, micro-alloying elements being additionally provided for forming wear-resistant phases and for improving the tribological properties.

Microalloys are those alloys which are predominantly formed from a constituent to which only minor amounts of further constituents are added relative to a total mass. Fine-grained pearlite, consisting of hard Fe3C and ferrite, is a tribologically positive effective phase. Bainite is a conversion phase of medium hardness and wear resistance. Martensite is a hard, wear-resistant structure. The formation of martensite can be selectively influenced by the type of cooling of the spray material and by the choice of alloying components of the microalloy.

Likewise, the ratio of bainite to perlite can be influenced in a targeted manner by the type of cooling of the spray material and by the choice of the alloy constituents of the microalloy.

A layer on a substrate, for example a cylinder running surface, produced by means of an arc wire spraying using the spray material according to the invention comprises perlite and bainite and wear-resistant martensite islands.

Tribologically active phases serve to improve the running behavior in critical system states, so that z. B. when tearing off lubricating films excessive wear of the friction partners or their damage can be avoided by adhesive reactions. These states occur especially in mixed friction regions, e.g. OT and UT areas in tribological systems Cylinder surfaces / piston rings.

In the following an embodiment of the invention will be explained in more detail with reference to a drawing.

Fig. 1

ein Substrat mit einer durch Lichtbogendrahtspritzen abgeschiedenen Schicht.

Showing:

Fig. 1

a substrate having a sheet deposited by arc wire spraying.

In FIG. 1 , For example, a substrate 1 with a sheet 2 deposited by arc wire spraying (LDS) is shown. When arc wire spraying a coating head 3, two wire-shaped spray materials 4 are supplied. Between the wire-shaped spray materials 4, an arc 5 is ignited. In this case, the wire-shaped spray material 4 melts and is selectively applied by means of a carrier gas to the substrate 1 to be coated, where it cools, solidifies and forms the layer 2.

The wire-shaped spray material 4 essentially comprises iron. The spray material is formed at least with carbon as a micro-alloy in such a way that pearlite and bainite are already formed upon solidification of the spray material. In addition, alloy constituents are provided in the microplating for the formation of wear-resistant phases of martensite and for reducing the coefficient of friction.

• Kohlenstoff 0,28 Gew.% bis 0,6 Gew.%,
• Silizium 0,6 Gew.% bis 0,8 Gew.%
• Mangan 1,0 Gew.% bis 1,4 Gew.%
• Chrom 0,05 bis 0,35 Ges.%
• Kupfer 0,04 Gew.% bis 0,15 Gew.%
• Stickstoff 0,005 bis 0,03 Gew.%

sowie optional Wahlbestandteile wie Vanadin, Nickel, Molybdän, Phosphor, Schwefel und Aluminium, sowie dem Rest Eisen und unvermeidlichen Verunreinigungen.The following alloy components are provided:

• Carbon 0.28 wt.% To 0.6 wt.%,
• Silicon 0.6% by weight to 0.8% by weight
• Manganese 1.0% by weight to 1.4% by weight
• Chromium 0.05 to 0.35 Total%
• Copper 0.04 wt% to 0.15 wt%
• Nitrogen 0.005 to 0.03% by weight

as well as optional constituents such as vanadium, nickel, molybdenum, phosphorus, sulfur and aluminum, as well as the remainder iron and unavoidable impurities.

The quantities are in percent by weight in each case based on a total weight, unless otherwise specified.

The elements vanadium, molybdenum, phosphorus, sulfur and aluminum and nickel are preferably contained at least in traces, i. in proportions of at least 0.001% by weight. Preference is given to maximum contents of 0.15% by weight. for vanadium, 0.1% by weight. for nickel, 0.03 wt.%. for molybdenum and 0.01 wt.%. for the other elements mentioned.

• Kohlenstoff 0,4 Gew.%
• Silizium 0,7 Gew.%
• Mangan 1,32 Gew.%
• Kupfer 0,06 Gew.%
• Chrom 0,19 Gew.%
• Stickstoff 0,015 Gew.%

According to a first exemplary embodiment, a microalloying with the following constituents is preferably used for the wire-shaped spray material 4:

• Carbon 0.4% by weight
• Silicon 0.7% by weight
• Manganese 1.32% by weight
• Copper 0.06% by weight
• Chromium 0.19% by weight
• Nitrogen 0.015% by weight

The main component of the microalloy is iron.

Arc wire spraying with a wire-shaped spray material 4 formed from these micro alloys results in a particularly homogeneous layer 2 with low porosity and low roughness.

The low carbon content and the increased manganese content and the increased silicon content of the microalloy result in an improved spray behavior, which is characterized in that small regular, viscous droplets are formed in the arc wire spraying. Due to their viscosity, they decay only slightly in flight and on impact to finer particles and thus tend less to oxidation. Lower surface oxidation promotes adhesion of the particles to the substrate - layer adhesion - and adhesion of the particles to each other - layered cohesion.

In addition, the increased manganese content leads to a predominantly pearlitic / bainitic microstructure during the solidification of the sprayed layer 2.

The addition of copper improves the corrosion protection of layer 2.

The addition of nitrogen promotes the formation of wear-resistant, nitrides, tribologically also effective in terms of a Reibwertreduzierung.

When layer 2 solidifies, fine-grained pearlite and bainite and wear-resistant martensite islands are formed. Bainite is a tough intermediate structure of carbonaceous steels. Perlite is a mixed structure of soft ferritic and hard carbide phases. The formation of bainite and perlite can be influenced by spray parameters, the type of cooling of the spray material and the choice of the alloy components of the microalloy. The layer 2 is formed in the form of a soft, ductile matrix of pearlite and bainite with hard, wear-resistant islands of martensite.

The wire-shaped spray material 4 is preferably hot rolled and / or hot drawn and then cooled slowly and controlled in an oven and / or annealed to obtain a ductile structure, so that the wire-shaped spray material 4 remains flexible.

The alloy components of the wire are dimensioned so that the burn-up of certain elements, eg carbon, is taken into account. The alloy composition of layer 2 is changed according to the burnup. The wire composition is tuned to the target properties of the sprayed layer

Preferably, a surface of the wire-shaped spray material 4 is copper plated in order to avoid corrosion.

The wire is low alloy, with the choice being geared specifically to low cost alloying elements.

The resulting sprayed coating exhibits good machinability and improved tribological properties as well as good wear resistance.

LIST OF REFERENCE NUMBERS

1

substratum

2

layer

3

coating head

4

wire-shaped spray material

5

Electric arc

Claims (5)

1. Wire-form material for spraying (4),
   in particular for light arc wire spraying,
   characterised in that
   the material for spraying (4) is formed at least with carbon as a micro-alloy in such a way that
   upon solidification of the spray material, pearlite, bainite and martensite are formed,
   characterised in that
   the following alloy parts are provided:

   - carbon 0.28 wt.% to 0.6 wt.%

   - silicon 0.6 wt.% to 0.8 wt.%,

   - manganese 1.0 wt.% to 1.4 wt.%

   - chromium 0.05 to 0.35 wt.%,

   - copper 0.04 wt.% to 0.15 wt.%

   - nitrogen 0.005 to 0.03 wt.%,

   and also optionally selected parts such as vanadium, nickel, molybdenum, phosphorus, sulphur and aluminium,
   as well as the remaining iron and unavoidable impurities,
   each with respect to a total weight.
2. Wire-form material for spraying (4) according to claim 1,
   characterised in that
   vanadium with a part of up to 0.15 wt.%,
   nickel with a part of up to 0.1 wt.%,
   molybdenum with a part of up to 0.03 wt.%,
   phosphorus, sulphur and aluminium with a part of up to 0.01 wt.%, are contained,
   each with respect to a total weight.
3. Wire-form material for spraying (4) according to one of the preceding claims,
   characterised in that a copper coating of a surface of the material for spraying (4) is provided.
4. Thermally sprayed layer on iron base,
   characterised in that
   it has the following alloy parts:

   - carbon 0.28 wt.% to 0.6 wt.%,

   - silicon 0.6 wt.% to 0.8 wt.%,

   - manganese 1.0 wt.% to 1.4 wt. %,

   - chromium 0.05 to 0.35 wt.%,

   - copper 0.04 wt.% to 0.15 wt.%,

   - nitrogen 0.005 to 0.03 wt.%,

   and also optionally selected parts such as vanadium, nickel, molybdenum, phosphorus, sulphur and aluminium,
   as well as the remaining iron and unavoidable impurities,
   each with respect to a total weight.
5. Thermally sprayed layer according to claim 4,
   characterised in that
   it is arranged as a running track layer inside a cylindrical crankcase of a piston engine.

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