EP2862685B1 - Method for separating bonded materials - Google Patents

Description

Field of the invention

The invention relates to a method for separating cohesively bonded surfaces of two materials, according to the preamble of claim 1, such as. B. from the DE 26 48 342 A known.

Background of the invention

It is known that two materials, at least one of which has an open-pored nanostructured surface, can be bonded together extremely tightly, since the open-pore nanostructuring ensures excellent adhesion of a wide variety of materials. Various methods for such a nanostructuring of surfaces by means of laser, electron or ion beam are described in the prior art.

However, if two such bonded materials are to be separated for whatever reason, this poses significant problems. In most cases, the only way to separate the materials, was that the second material connected to the open-pore nanostructured surface of a material was mechanically abraded, if it is a relatively thin coating or structure, or that the composite material on the Connecting surface was sawn through.

It was the object of the invention to provide a simpler method of separating such bonded materials.

Summary of the invention

The invention relates to a method for separating cohesively bonded surfaces of two materials, of which at least one is a material whose materially bonded surface has an open-pore nanostructuring and a solid inorganic material, an inorganic / organic A composite material and / or a solid plastic, the method being characterized in that the open-cell, nanostructured cohesively bonded surface at a temperature which is at least 150 ° C lower than the melting temperature of the solid inorganic material, the inorganic / organic composite material or at least 50 ° C is lower than the softening temperature of the solid plastic, is heated until the originally open-pore nanostructured surface no longer has open-pore nanostructures, and then the surfaces of the two materials are separated.

Short description of the drawing

• Fig. 1 shows in a magnification of 30,000 times the nanostructured, laser-irradiated, highly porous surface of a TiAL6V4 sample.
• Fig. 2 shows, at 20,000 times magnification, the no longer open-pored surface of the TiAL6V4 sample, restructured by a heat treatment at 950 ° C Fig. 1 ,
• Fig. 3 shows in a magnification of 30,000 times the nanostructured, laser-irradiated, highly porous surface of an Al 2024 sample.
• Fig. 4 shows in 30,000-fold magnification, by a heat treatment at 400 ° C restructured, no longer porous surface of the Al 2024 sample of Fig. 3 ,
• Fig. 5 shows, in a magnification of 30,000 times, the nanostructured, highly porous surface of a V2A steel sample by means of laser radiation.
• Fig. 6 shows in 30,000-fold magnification, by a heat treatment at 800 ° C restructured, no longer porous surface of the V2A steel sample of Fig. 5 ,
• Fig. 7 shows in a magnification of 30,000 times the laser-nanostructured, strongly open-pore surface of a carbon fiber-reinforced SiC (C / SiC) ceramic sample.
• Fig. 8 shows in 30,000 times the magnification of the restructured by a heat treatment at 1100 ° C, no longer porous surface of the C / SiC ceramic sample of Fig. 7 ,

Detailed description

An open-pored nanostructuring of a material surface ensures that a further material connected to it can strongly "interlock" with the latter, which leads to a very strong connection of the two materials, which is difficult to solve.

It has now surprisingly been found that heating the open-pore nanostructured surface of a material at a temperature which is considerably below the melting temperature or softening temperature of the material causes a restructuring of the previously open-pore, nanostructured surface, in which now the open pores have disappeared and smoothed Surface structures are present. As a result, the "gearing" is released with a material connected to the surface, so that it can be relatively easily separated from the surface.

According to the invention, the solid inorganic material of the material surface with open-pored nanostructures, from which the second material surface is to be separated, preferably comprises a metal, a metal alloy, a metal chalcogenide, a metal salt, a metal-containing nitrogen, phosphorus, arsenic and / or antimony compound Semi-metal or an alloy thereof, a ceramic, an inorganic glass, carbon, an inorganic fibers and / or non-fibrous carbon and / or boron nitride-containing composite material with ceramic and / or carbon matrix, a metal-ceramic composite material, a composite material of a metal and / or a metal alloy containing thermally conductive carbonaceous and / or boron nitride-containing particles and / or fibers and / or a composite of a metal and / or a metal alloy, the thermally conductive carbonaceous and / or boron nitride-containing Contains particles and / or fibers and is at least partially coated with an oxide layer. The inorganic / organic composite material preferably comprises a ceramic or / and carbon matrix composite containing organic or inorganic / organic fibers and / or a plastic matrix composite containing inorganic, organic or inorganic / organic fibers and the plastic preferably comprises a thermoplastic, an elastomer, a thermoplastic elastomer, a thermoset and / or a silicon-containing plastic. The material of the surface having an open-pored nanostructure may also comprise a combination of at least two of the above-mentioned materials.

The metal or metal alloy may for example be selected from iron, aluminum, tantalum, magnesium, copper, nickel or titanium or an alloy thereof, eg Ti-6Al-4V, pure titanium, Mg-4Al1-Zn, Ta-10W, Cu-oF, CuZn37, Al 2024 (Al-4.4Cu-1.5mg-O.6Mn), V2A-steel (X5CrN18-10) and Inconel 718 ^® (high temperature nickel alloy with Ni-19Cr-18Fe-3Mo-5Nb-0, 05C (material number 2.4668)).

The metal chalcogenides (ie, oxides, sulfides, selenides, and tellurides) may be present in a very thin layer on the parent metal or base metal alloy. This is especially true for oxide passivation layers.

The same applies to metal-containing nitrogen, phosphorus, arsenic and / or antimony compounds, in which in particular metal nitride protective layers on the base metal or the base metal alloy can be very thin.

The metal salts may be any of the known metal salts, for example, halides such as chlorides, sulfates, nitrates, phosphates and other complex anions and salts with mixed cations and / or anions Surfaces of the invention may include semimetals such as beryllium, boron, and silicon, their alloys with themselves or with metals, and solid compounds with non-metals.

The ceramic or ceramic of the ceramic matrix of the composite material from which the surface material according to the invention may be formed may be selected from all known ceramics. These include silicate ceramics, oxide ceramics such as alumina, silica, alumina-silica (mullite), SiOC, beryllium oxide, zirconium (IV) oxide and aluminum titanate, and mixtures thereof such as Al ₂ O ₃ -SiO ₂ / SiOC, non-oxide ceramics such as silicon carbide. Tungsten carbide, silicon nitride, boron nitride, aluminum nitride, SiCN and molybdenum disilicide and ceramics of mixtures of the above ceramics.

The ceramic surface material according to the invention may also be a ceramic coating.

Other ceramic materials (but not exhaustive) used especially, but not exclusively, as coatings are the carbides B ₄ C, TiC, TaC, HfC, ZrC, Cr ₃ C ₂ , Al ₄ C ₃ , MoC ₂ , NbC and VC, the nitrides TiN, CrN _1-x , CrN, Li ₃ N. TaN, and ZrN, the silicides WSi ₂ and ZrSi ₂ , the borides ZrB ₂ , HfB ₂ , TiB ₂ , LaB ₆ , Cr _B , CrB ₂ , AlB ₂ , MgB ₂ and SiB ₆ and the oxides CaO, MgO, ThO ₂ , TiO ₂ , P ₂ O ₅ , SiAlON, Y ₂ O ₃ , HfO ₂ , ZrO ₂ and B ₂ O ₃ .

The plastic or the plastic of the plastic matrix of the composite material from which the surface material according to the invention can be formed, are generally thermoplastics and thermoplastic mixtures, such as polyethylene, polypropylene, polystyrene, polyester or polyetheretherketone or mixtures thereof, elastomers, thermoplastic elastomers and their mixtures, such as block copolymers of styrene and polyolefins, and thermosets or mixtures thereof, such as bakelite, polyester resins, polyurethane resins and epoxy resins and mixtures thereof, and Mixture of the aforementioned plastics. Furthermore, the plastic may also be a silicon-containing plastic, such as a silicone.

The carbon or carbon of the carbon matrix of the composite material from which the surface material according to the invention may be formed is usually harder carbon variants such as vitreous carbon, diamond-like carbon, pyrolytically produced graphite or by vapor deposition or vapor deposition or vapor deposition chemical vapor deposition) produced carbon.

The composites that may comprise the surface material of the present invention may be fiber-containing composites (fiber reinforced composites) having the above matrices, as well as mixtures thereof.

The inorganic composite fibers may be any of the inorganic fibers known to those skilled in the art for composite use. These include in particular carbon fibers, glass fibers and ceramic fibers. The fibers can be short or long or endless and can be connected to rovings (multifilaments).

Particularly preferred ceramic fibers are based on oxide ceramic filament fibers, in particular Al ₂ O ₃ or Al ₂ O ₃ / SiO ₂ (mullite) fibers and / or non-oxide ceramic filament fibers, in particular SiC, SiCN and SiBNC fiber types.

Preferred organic composite fibers are aramid fibers. But it can also be used other fibers of artificial and natural polymers.

Frequently, the fibers in the fiber reinforced composites are coated to ensure a weak fiber-matrix interfacial interaction. This is usually required for good mechanical behavior and fiber protection. Such coatings can eg pyrolytic carbon, SiC, BN, LaPO ₄ , CePO ₄ , CaWo ₄ , ZrO ₂ , mullite, Al ₂ O ₃ , magnetoplumbite, α-aluminate structures, LaAl ₁₁ O ₁₈ , CaAl ₁₂ O ₁₉ , BaM ₉₂ Al ₁₆ , O ₂₇ , KMg ₂ Al ₁₅ O ₂₅ , lanthanum and calcium hexaaluminates, hexalaluminates, organometallic compounds or mixtures and / or multilayers thereof. When the coated fibers contain both inorganic and organic components, they are referred to herein as "inorganic / organic fibers".

The fiber reinforced composites may contain additional inert or passive fillers, e.g. Ceramic powder that is not bonded to the ceramic matrix, if used.

By non-fibrous carbon and / or boron nitride containing ceramic, plastic or carbon matrix composites from which the surface material of the present invention may be formed is meant ceramic or carbon matrices provided with carbonaceous particles other than carbon fibers. These carbonaceous particles include, in particular, graphitic particles, carbon nanotubes, fullerenes and diamond-like particles. The boron nitride is preferably cubic boron nitride particles.

Another composite material that may comprise the surface material is metals and / or metal alloys that contain thermally conductive carbonaceous and / or boron nitride-containing particles and / or fibers and that may be at least partially coated with an oxide layer. These fibers and particles may be, in particular, carbon fibers, graphitic particles, carbon nanotubes, diamond-like particles, boron nitride fibers, and cubic boron nitride particles.

The surface material may also comprise metal-modified ceramics, ie metal-ceramic composites.

As already mentioned, methods for applying an open-pored nanostructure to these surface materials are known to the person skilled in the art. They generally involve scanning the surface with a pulsed laser beam or even with an electron or ion beam under certain process conditions.

The material of the surface of the second material may be independently selected from the same materials mentioned above as materials for the open-pore nanostructured surface of the first material.

Optionally, the surface of the second material may also be provided with an open-pore nanostructure in this case.

Alternatively, the second material (and thus also its cohesively bonded surface) may be selected from a different material from the above described materials. It may, for example, be a coating comprising a varnish, a sealant, a solder, a coating for protection against mechanical, chemical or thermal effects, for repelling dirt or for reducing the adhesion, bone cement or a biological material.

Optionally, a mostly very thin adhesive layer or an adhesion promoter layer can be located between the two cohesively bonded surfaces of the two materials. The primer may be e.g. a silane coupling agent, a titanate such as titanium tetraisopropylate or titanium acetylacetonate, a zirconate such as zirconium tetrabutoxide, a zirconium aluminate, a thiazole, a triazole such as 1H-benzotriazole, a phosphonate or a sulfonate.

As already mentioned, it has surprisingly been found that the temperature at which a restructuring of the open-pored, nanostructured surface already takes place is considerably below the melting point or softening point of the surface material. For inorganic materials and composite materials, the temperature is usually at least 150 ° C below the melting point, but it may still be much lower, for example at least 200 ° C to several hundred ° C lower than the melting temperature, as shown in the examples. For plastics, the required temperature is usually at least 50 ° C, often 80 ° C below the softening point of the plastic. The required temperature also depends on the heating time, so that there is a temperature range in which the restructuring of the surface can take place.

By additionally applying pressure to the bonded surfaces, the temperature required for the restructuring can be further reduced.

The heating time to complete disappearance of the open pores of the nanostructure depends primarily on the surface material and on the actual temperature applied (lower temperatures require a longer heating time for the same material). In general, one will choose the temperature so that a heating time of about 3 to about 30 minutes is sufficient.

It should also be mentioned that after the heat treatment according to the invention, the open pores have disappeared and smooth surface structures are present, but they may still have dimensions in the nanometer range.

The heating of the open-pored nanostructured surface (s) can be accomplished in any manner known to those skilled in the art, taking into account the specific composite material. Below are some examples given.

For example, smaller composite materials can simply be placed in an oven at the required temperature.

Electrically conductive surface materials can be very advantageous, because quickly brought by induction heating to the required temperature and held it.

In particular, if one of the two materials is a relatively thin coating, the open-pored nanostructured surface can be heated through the coating with a laser, electron or ion beam or with infrared radiation. Alternatively, if appropriate, this can also be done from the back of the surface.

By hot-isostatic pressing of the entire composite material, the surface can be heated simultaneously and pressurized.

Another way to heat the surface is to use small drills or laser beams to drill fine channels down to the nanostructured surface and heat them by introducing a hot fluid. In particular, hot deionized water, hot steam and hot air with at least 40% relative humidity are suitable as the fluid.

Once the porous nanostructured surface has smoothed, the previously firmly bonded materials can be easily removed mechanically. Coatings such as paints or other coatings usually stand out by themselves. Even adhesive layers and associated second materials can be easily lifted off. Even though the surfaces of both materials had open-pore nanostructures and the materials were bonded together and "interlocked" by direct compression, they can simply be pulled apart by heating after smoothing of both surfaces.

Any remaining remains of, for example, paint, adhesive or adhesion promoter can be easily removed by suitable solvents, since they are now no longer difficult to access in open pores.

The following examples further illustrate the invention.

Examples example 1

A component made of TiAl6Va had been provided with a strongly open-pore surface by means of laser radiation (see Fig. 1 ).

The component was heated in an oven for about 65 minutes to a temperature of about 950 ° C and held for about 20 minutes.

Thereafter, the surface was restructured and smoothed and no longer had open pores (see Fig. 2 ).

Example 2

In this example, the surfaces of two Al 2024 devices were laser-patterned with open-pore nanostructuring (see Fig. 3 ) and then glued.

Then fine channels were drilled in the two components to below the surfaces and 400 ° C hot steam was injected for about 5 minutes.

Thereafter, the surfaces were restructured and smoothed and no longer showed any open pores (see Fig. 4 ), with the result that the two components could easily be pulled apart, since the adhesive could easily be lifted off the two smoothed surfaces.

Example 3

A component made of V2A steel had been provided with a strongly open-pore surface by means of laser radiation (see Fig. 5 ).

The component was heated by means of an induction heater within about 5 seconds to a temperature of about 800 ° C and held for about 5 minutes.

Thereafter, the surface was restructured and had fine needle-shaped structures with a smooth surface without open pores (see Fig. 6 ).

Example 4

A component made of carbon fiber-reinforced SiC (C / SiC) ceramic had been provided with a strongly open-pore surface by means of laser radiation (see Fig. 7 ).

The component was heated in an oven for about 90 minutes to a temperature of about 1100 ° C and held for about 15 minutes.

Thereafter, the surface was restructured and smoothed and no longer had open pores (see Fig. 8 ).

Claims (15)

1. A method for separating adhesively bonded surfaces of two materials, of which at least one is a material of which the adhesively bonded surface comprises an open-pored nanostructuring and a solid inorganic material, an inorganic/organic composite material and/or a solid plastic, characterized in that the open-pored, adhesively bonded nanostructured surface is heated to a temperature that is at least 150 °C lower than the melting temperature of the solid inorganic material and the inorganic/organic composite material, or at least 50 °C lower than the softening temperature of the solid plastic, until the originally open-pored nanostructured surface no longer has any open-pored nanostructures, and the surfaces of the two materials are then separated.
2. The method according to claim 1, characterized in that the solid inorganic material comprises a metal, a metal alloy, a metal chalcogenide, a metal salt, a metal-containing compound of nitrogen, phosphorus, arsenic and/or antimony, a semi-metal or an alloy thereof, a ceramic, an inorganic glass, carbon, a composite material with a ceramic and/or carbon matrix containing inorganic fibres and/or non-fibrous carbon and/or boron nitride, a metal-ceramic composite material, a composite material consisting of a metal and/or a metal alloy that contains thermally conductive particles and/or fibres containing carbon and/or boron nitride, and/or a composite material consisting of a metal and/or a metal alloy that contains thermally conductive particles and/or fibres containing carbon and/or boron nitride and is at least partially coated with an oxide layer, the inorganic/organic composite material comprises a composite material with a ceramic and/or carbon matrix containing organic or inorganic/organic fibres and/or a composite material with plastic matrix containing inorganic, organic or inorganic/organic fibres, and the plastic comprises a thermoplastic, an elastomer, a thermoplastic elastomer, a thermosetting plastic and/or a silicon-containing plastic.
3. The method according to either of claims 1 or 2, characterized in that the surfaces of both materials independently comprise a solid inorganic material, an inorganic/organic composite material or a solid plastic, wherein only one surface has an open-pored nanostructuring.
4. The method according to either of claims 1 or 2, characterized in that the surfaces of both materials independently contain a solid inorganic material, an inorganic/organic composite material or a solid plastic, wherein both surfaces have an open-pored nanostructuring.
5. The method according to either of claims 1 or 2, characterized in that the second material is a coating comprising a lacquer, a sealant, a solder, a coating for protection against mechanical, chemical or thermal effects, for repelling dirt or reducing adhesion, bone cement or a biological material.
6. The method according to any one of claims 1 to 5, characterized in that a layer of adhesive or bonding agent is located between the two adhesively bonded surfaces.
7. The method according to any one of claims 1 to 5, characterized in that the two adhesively bonded surfaces are bonded directly with each other.
8. Method according to any one of claims 1 to 7, characterized in that the open-pored, nanostructured, adhesively bonded surface(s) is/are heated to a temperature that is at least 200 °C lower than the melting temperature of the solid inorganic material and the inorganic/organic composite material, or at least 80 °C lower than the softening temperature of the solid plastic.
9. The method according to any one of claims 1 to 8, characterized in that the heating of the surface(s) by heating the two materials whose surfaces are adhesively bonded, is carried out in an oven.
10. The method according to any one of claims 1 to 8, characterized in that the heating of the surface(s) is performed by induction heating.
11. The method according to any one of claims 1 to 8, characterized in that the heating of the surface(s) performed by a laser, electron or ion beam or by infrared radiation.
12. The method according to any one of claims 1 to 8, characterized in that the heating of the surface(s) is accomplished by supplying a hot fluid to the surface through channels drilled into the workpiece.
13. The method according to any one of claims 1 to 8, characterized in that the fluid comprises hot water, hot steam or hot air with at least 40° relative humidity.
14. The method according to any one of claims 1 to 13, characterized in that the separation is carried out mechanically by lifting one of the materials or by peeling the two materials apart.
15. The method according to claim 14, characterized in that after separation at least one of the previously bonded surfaces of the separated workpieces undergoes treatment with a solvent.

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