EP3658693A1

EP3658693A1 - Wire material consisting of a copper alloy, mesh and breeding cage for aquaculture

Info

Publication number: EP3658693A1
Application number: EP18738193.4A
Authority: EP
Inventors: Benjamin Figelius; Timo ALLMENDINGER; Daniel Steitz; Susanne BÖHME
Original assignee: Wieland Werke AG
Current assignee: Wieland Werke AG
Priority date: 2017-07-27
Filing date: 2018-06-27
Publication date: 2020-06-03
Also published as: JP2020528492A; DE102017007138B3; WO2019020208A1; US20210120791A1; US11172659B2; CN111051547A; JP6993436B2

Abstract

The invention relates to a wire material consisting of metallic material having an oxide surface, wherein the oxide surface of the wire material has a first oxide layer, which covers the metallic material at least in part and has a thickness of at least 200 nm to 2 μm, and the oxide surface of the wire material has a second oxide layer which covers metallic material in the regions which are not covered by the first oxide layer. According to the invention, the second oxide layer has a maximum thickness of 0.01 to 10% of the thickness of the first oxide layer. The invention furthermore relates to a mesh and a breeding cage for aquaculture.

Description

description

WIRE MATERIALS FROM A COPPER ALLOY, NET AND BREEDING CAGE FOR AQUACULTURE

The invention relates to a wire material consisting of metallic material with an oxide surface according to the preamble of claim 1, a network according to the preamble of claim 1 1 and a breeding cage for aquaculture according to the preamble of claim 12.

Maritime fish farming today uses coated or uncoated polymer nets and metal cages. Requirements for materials used in the production of aquaculture net cages include good chemical resistance in seawater and high mechanical strength to withstand short-term peak loads, for example by the impact of debris or attack by predators, as well as swell, current and To be able to withstand tides.

A significant further development of existing solutions only occurs if numerous requirements for the material are fulfilled at the same time.

Basically, copper-based alloys have a great potential, the

Requirements against a chemical attack, a growth by micro and macroorganisms (biofouling) and a mechanical load at the same time to meet. For some years they are also in

Test plants tested. Experience has already been gained with a tin-containing special brass. This alloy is used for example in the

Document EP 1 777 31 1 A1 described in more detail. In addition, the come

Copper-nickel alloy CuNM OFel Mn and silicon bronzes are used. Particularly suitable for use in seawater are alloys from the group of so-called admiralty brasses. These are also Cu-Zn alloys whose corrosion resistance in seawater is improved by adding Sn and an element of the group As, P or Sb. Examples are the alloys C44300, C44400 and C44500.

A net or a breeding cage for use in aquaculture is according to the publication WO 2010/049089 A1 formed as a wire mesh, which can be produced from individual helical or similar bent longitudinal elements, wherein the adjacent wires are each braided together. The

Longitudinal elements are made of metal wires and made of seawater-resistant steel, which is provided with an antifouling surface. These nets are attached to each other, for example, by shackles or the like. In addition, EP 2 664 236 A1 discloses a network which is intended for animal breeding, such as fish, shellfish or mollusc farming in waters. The net is made of metal wires, ropes and / or strands.

The invention has for its object to provide a wire material for a network for a breeding cage in aquaculture in terms of improving the

To develop corrosion properties.

The invention is related to a wire material by the features of

Claim 1, relating to a network by the features of claim 1 1 and with respect to a breeding cage by the features of claim 12

played. The other dependent claims relate to advantageous embodiments and further developments of the invention.

The invention includes a wire material consisting of metallic material having an oxide surface, wherein the oxide surface of the wire material is a first Having oxide layer which partially covers the metallic material and has at least a thickness of 200 nm to 2 pm, and the oxide surface of the wire material has a second oxide layer, which is the metallic

Cover material in areas not covered by the first oxide layer. Here, the second oxide layer has a thickness of at most 0.01 to 10% of the thickness of the first oxide layer.

When using different metal alloys, corrosion-resistant copper alloys are particularly suitable for use in sea, brackish or fresh water. In the case of the wire material according to the invention, particular importance is attached to the formation of the oxide surface, which is based on a suitable combination of different pressing or drawing processes. Such transformations may be hot working or cold working and intermediate annealing. The formation of the oxide surface must be technically matched to the exact degree of the process. Only in this way can the optimum of the expected properties of the first and second oxide layers be achieved.

For example, the wire material is made by wire drawing through a combination of intermediate annealing in air in conjunction with a

Cold forming or multiple cold forming and intermediate annealing to the desired final gauge of the wire in the preferred range of 2 to 5 mm.

The metallic material can also be present in a recrystallized state, for example, in the case of suitable copper alloys by a

Annealing can be adjusted after the last cold forming step. This condition is particularly favorable for the production of woven

Network structures, since the formability of metals recrystallized state is particularly large. The oxide surface thus forms a closed surface layer on the metallic material with flat areas of different thickness. For an application in the field of aquaculture, inter alia, the metal release in seawater in the foreground. On the one hand, it showed that the

Oxide surface causes that overall a much lower element delivery of the metallic material to the sea water takes place, as with bare surfaces. On the other hand, when using alloy types which have antifouling properties due to their elemental content, some mass transfer over the surface must be possible. In this case, the first oxide layer has a sufficient thickness to a discharge of

Alloy elements such as copper to suppress as much as possible, whereas compared to the first oxide layer much thinner second oxide layer allows this exchange of material in favor of antifouling properties. In this way, the wires can be optimally matched depending on the area ratio of the first or second oxide layer with respect to a corrosion protection of the metallic material or the antifouling properties. With a high areal proportion of the first oxide layer, the corrosion protection predominates. With increasing area fraction of the thin second oxide layer, the antifouling properties can be improved in alloys suitable for this purpose.

A particular advantage of the solution according to the invention results from a significant improvement, with several more in terms of corrosion resistance and antifouling properties, especially in seawater

Requirements can be weighed and optimized. In the field of aquaculture, the use of copper materials for metal meshes pays special attention to the release of the alloying elements to the environment. The solution according to the invention allows this requirement to be taken into account with regard to a sustainable solution. Basically, with the

Wire material according to the invention a reduction of the element delivery can be achieved in principle or at least over a long period of time. The initial oxide oxide surface of the wire material according to the invention, which is not initially formed under conditions of use, also ensures extremely low abrasion in use in aquaculture applications, in particular in the event of cyclic stress caused by swell or current.

In a preferred embodiment of the invention, the first oxide layer may be arranged on the surface of the wire material segment-like and / or band-like. As a result, the metallic material is partially covered with a surface-like island-like or flat band-like oxide film, which in its entirety represents a substantially homogeneous surface with respect to a friction partner. As a result of the first oxide layer, a surface resistant to mechanical wear results in the friction collective with mostly identical friction partners

Aquaculture applications.

Advantageously, the surface portion of the first oxide layer on the

Oxide surface of the wire material 60 to 99%. With such a cover, a particularly preferred area ratio is given for low-wear layers.

In a further preferred embodiment of the invention, the area ratio of the first oxide layer on the oxide surface of the wire material can be 80 to 95%. As a result, an area of the first oxide layer adapted to wear with the thin second oxide layer with respect to one becomes

Antifouling properties optimized material. With regard to the corrosion resistance or the antifouling properties in seawater, several requirements can be weighed and particularly optimized with these area percentages. Advantageously, the metallic material may be a copper alloy. Particularly corrosion resistant copper alloys are suitable for use in sea, brackish or fresh water. Especially such alloys also a

Have resistance to fouling under water. Thus, from such alloys, wires for use in making cages for aquaculture use may serve as the starting material, which also have higher strength than most conventional materials.

Advantageously, the copper alloy may consist of (in% by weight):

51, 8 to 84.0% Cu,

15.5 to 36.0% Zn,

0.35 to 3.0% Sn,

From 0.12 to 1.5% Fe,

0.02 to 1.0% P,

alternatively still 0.1 to 2.0% AI

optionally still 0.05 to 0.7% Si

optionally still 0.05 to 2.0% Ni

optionally in each case 0.1 to 1, 0% Mn, Co

optionally each still 0.01 to 1, 0% As, Sb

and unavoidable impurities exist.

The microstructure can consist of more than 95% of α-mixed crystal, in which at least iron phosphides and / or iron are incorporated as precipitation particles. A zinc content of 15.5 to 32.0% is selected in the alloy, in particular according to the criterion that an easily deformable, single-phase alloy is obtained. The single-phase basic structure consists of alpha phase. Also, the basic structure must be suitable to absorb the finest possible precipitates of other elements. For zinc contents of 32.0 to 36.0% may to some extent still another ß-phase occur, but by a Temperature treatment can be reduced. The zinc content should not exceed 36.0%, as otherwise sets a less favorable phase properties in the alloy. Especially at over the specified value

Going out zinc content occurs in this context undesirable brittle gamma phase. On the other hand, extensive

Investigation results of an alloy variant with well over 30.0% zinc, that the desired properties are still ensured. An important property of the alloy itself is its resistance to corrosion attack and good processability.

From a technical point of view, a higher tin content in the alloy affects the strength and corrosion resistance. On the other hand, the tin content should not exceed 3.0%, as its flexibility is adversely affected. In principle, the tin concentration should be kept as low as possible, but at a level below 0.3% is not a significant influence on the

Alloy properties more to be expected.

By adding suitable proportions of Fe and P, phosphides in the form of precipitation particles can be formed in Cu-Zn-Sn alloys. These are either iron phosphides or mixed phosphides, such as manganese, nickel, cobalt phosphides. There may also be copper phosphides. In addition, iron particles in the

Excrete alloy matrix. Iron is responsible for the formation of precipitate particles and thus for an improvement in the strength properties in comparison to conventional admiralty brasses. The excretion formation can during the

Controlled and optimized manufacturing process. In particular, precipitates form in this alloy during a hot working step and subsequent cooling. The hardening effect of the alloy Mechanisms are primarily supported by the element iron. The iron-containing particles present in the alloy matrix form during this process

preferably in submicrometer range. As elements are also the elements As and Sb, the

have dezincification effect. It is also contemplated that As and Sb with Fe form compounds that could serve the particle curing of a Cu-Zn-based alloy with α-mixed crystal structure. It is further contemplated that Co, Mn and Ni can form such compounds with P, As and Sb. It can also contain a certain amount of Al, Mn, Ni and Si the corrosion resistance of

Increase Cu-based alloys in seawater.

The input of alloying elements, for example of copper, can be varied at least up to a factor of 10 in seawater, depending on the proportion of surface coverage by the first and second oxide layers.

This alloy has a high load-bearing capacity to support its own weight when used for netting and, for example, to fend off attacks by marine predators. Also, this type of alloy has good fatigue resistance to the cyclic stress due to swell or flow.

In an advantageous embodiment of the invention, the copper alloy may have a content of 0.7 to 1.5% Sn and / or 0.15 to 0.7% Fe. A lower tin content in the specified limits is therefore particularly advantageous, since in the first place the flexibility of the alloy is further improved. The specified iron content is selected so that particularly fine iron-containing particles can form in the alloy matrix. However, these particles still have the size to significantly improve the mechanical properties. In a preferred embodiment of the invention, the copper alloy may have a content of 0.4 to 1.2% Al. This increases the corrosion resistance of Cu-based alloys in seawater. In a particularly preferred embodiment, the following applies for the P / Fe ratio of the copper alloy: [P] / [Fe]> 0.25. In order to ensure a dezincification resistance of the alloy, it is important to keep the ratio of the

Phosphorus content to iron content should not be too low, otherwise the entire dissolved in the α-mixed crystal phosphorus, which acts as Entzinkungsinhibitor is bound in the form of iron phosphides. In this form is his

anti-inflammatory effect not given effectively. It has been found that in the test for dezincification resistance alloys resistant to the ratio P / Fe are: [P] / [Fe]> 0.25. More preferably, the ratio P / Fe: [P] / [Fe]> 0.5.

In a further advantageous embodiment of the invention, the tensile strength R _{m of} the metallic material can be at least 400 MPa. This results in a high load capacity to carry the weight of the braids or grid and to fend off, for example, attacks by marine predators can.

A wire made of this alloy or other structure made of this alloy thus has significantly greater resistance to plastic deformation and failure by fracture.

Another aspect of the invention includes a net with meshes of the wire material of the invention having an oxide surface.

This aspect of the invention is based on the consideration that

Network segments, which can also be designed as elongated network tracks, with a suitable connection system, for example, to a cage, are connectable for aquaculture. This results in the possibility to produce cages of greater stability and life, or alternatively reduce the wire diameter to save material. In particular, the increased strength associated with the copper alloy described above is already in the as-annealed condition, which may be particularly beneficial for processing operations such as braiding.

Another aspect of the invention includes an aquaculture breeding cage comprising a wire mesh mesh with an oxide surface.

The invention is based on the consideration that it is in the rearing in particular fish as well as crustaceans and mussels. For this a so-called aquaculture is operated, with which a controlled rearing of aquatic organisms in the sea is pursued. It is mostly based on

Net enclosures in the sea where, for example, salmon or other food fish are reared.

Here, for a network connecting elements cause a loose or even a rigid connection of network segments. The fixation by rigid

Connecting elements serve to stiffen the interface between two network segments, whereby at these locations, the cage in use under the influence of currents or waves does not deform greatly.

Further embodiments of the invention will be explained in more detail with reference to Table 1. Cast bolts of a copper-zinc alloy were produced by chill casting. The chemical composition of the casts is shown in Table 1. Table 1: Chemical composition of the alloy:

Production sequence:

• Extrusion into bars at a temperature of approximately 700 ° C.

· Wire drawing by combination of cold forming / intermediate annealing in air (550 ° C / 4h) to the final thickness of about 2.5 mm and 4 mm.

After continuous production, wire material having an oxide surface with a pickled surface wire material was passed through

Wear test compared.

In the wear test, two wires are crossed over each other and the upper one is moved back and forth in the longitudinal direction. The mass loss resulting from this friction as well as the reduction of the diameter provide information about the wear resistance. The pressure exerted by the wires on each other can be varied. In the investigations, 13 N load and 2000 strokes with different load cycles were chosen as test parameters. The strokes were divided into 4 load cycles with 500 strokes, each with a 30-minute break. The break between the load cycles ensures that also different corrosion behavior, ie the formation speed and adhesion of corrosion protection layers, is included in the wear test. In the abrasion test, alloy 1 and 2 performed best on all surface finishes. The alloys with an oxide surface according to the invention showed no measurable removal compared to the comparative samples in the wear test.

In addition, different experiments have been carried out for element delivery in seawater. This is based on the following tests: Alloys 1 and 2 in the surface state blank with oxide surface and alloy 3 with aluminum in the surface state blank with oxide surface. For alloys 1 and 2, the element delivery through the oxide layer is significantly reduced.

Alloy 3 with aluminum already contains one with this element

Corrosion inhibitor and shows low values even when bare. The condition with an oxide surface according to the invention nevertheless provides a further contribution to seawater resistance.

Claims

claims

Wire material consisting of metallic material with a

Oxide surface, characterized

- That the oxide surface of the wire material has a first oxide layer, which partially covers the metallic material and has at least a thickness of 200 nm to 2 pm, and

in that the oxide surface of the wire material has a second oxide layer covering the metallic material in the areas not covered by the first oxide layer, the second

Oxide layer has a thickness of at most 0.01 to 10% of the thickness of the first oxide layer.

Wire material according to claim 1, characterized in that the first oxide layer is arranged on the surface of the wire material segment-like and / or band-like.

Wire material according to claim 1 or 2, characterized in that the surface portion of the first oxide layer on the oxide surface of

Wire material is 60 to 99%.

Wire material according to claim 3, characterized in that the

Area fraction of the first oxide layer on the oxide surface of the

Wire material is 80 to 95%.

Wire material according to one of claims 1 to 4, characterized in that the metallic material is a copper alloy. Wire material according to claim 5, characterized in that

the copper alloy, out

(in% by weight):

51, 8 to 84.0% Cu,

15.5 to 36.0% Zn,

0.35 to 3.0% Sn,

From 0.12 to 1.5% Fe,

0.02 to 1.0% P,

alternatively still 0.1 to 2.0% AI

optionally still 0.05 to 0.7% Si

optionally still 0.05 to 2.0% Ni

optionally in each case 0, 1 to 1, 0% Mn, Co

optionally each still 0.01 to 1, 0% As, Sb

and unavoidable impurities.

Wire material according to claim 6, characterized by a content of 0.7 to 1.5% Sn and / or 0.15 to 0.7% Fe.

Wire material according to claim 6 or 7, characterized by a content of 0.4 to 1, 2% AI.

Wire material according to one of claims 6 to 8, characterized in that the following applies to the P / Fe ratio: [P] / [Fe]> 0.25.

Wire material according to one of claims 1 to 9, characterized in that the tensile strength R _{m of} the metallic material is at least 400 MPa.

Mesh with meshes of wire material having an oxide surface according to one of claims 1 to 10. Aquaculture breeding cage comprising a wire mesh mesh with an oxide surface according to any one of claims 10 to 10.