DE202007010344U1 - Multi-component inorganic binder and composite system - Google Patents

Abstract

chemical and / or physically curable or solidifying, multicomponent binder, wherein at least a first component of the binder before curing or Solidify as an inorganic, nanofine powder with a medium Particle size ≦ 1 microns and a second component of the binder as a reactant for the first Component and / or as a reaction accelerator or catalyst in the form of an inorganic or aqueous liquid, characterized characterized in that as a third component a metal powder with a mean particle size of 10 microns provided which has soft metal properties.

Description

The The invention relates to a chemically and / or physically curable or solidifying, multicomponent binder, wherein at least one first component of the binder before curing or solidifying as inorganic, nanofine powder with an average particle size ≦ 1 μm and a second component the binder as a reactant for the first component and / or as Reaction accelerator or catalyst in the form of an inorganic or aqueous liquid available.

Such a binder is, for example, from DE 198 12 577 C1 known.

you distinguishes between organic and inorganic adhesives.

organic Adhesives have a very limited heat resistance, their use e.g. in mechanical engineering and construction often restricts. It ranges from commercial up to high-strength structural adhesives up to approx. 200 ° C, but not chemically unambiguous attributable to silicone adhesives up to 330 ° C and polyimide adhesives and their descendants up to 400 ° C.

Long-term temperature resistance from 400 ° C up to 1500 ° C, the solution a number of bonding and potting problems in today's technology are required can only be achieved with inorganic binder.

inorganic Binders are already known from the first half of the 20th century. There were especially water glass products, especially for small-scale, heat-resistant and vibration-free connections were used. however fails their application, e.g. in device production, often at the brittleness, because of which they are barely able to have larger strain differences between compensate for the components to be joined and vibration stresses and operational deformations.

All in all inorganic non-metallic binders are characterized by low Flexibility and high brittleness out. This pushes her Usability despite positive properties such as heat resistance, Incombustibility, great Hardness and Chemical resistance there to their limits, where in addition about vibration resistance, thermal expansion and operational deformations goes.

Commercially available inorganic Binders, in particular adhesives, are based primarily on aluminum oxide, Aluminum silicate, silica, zirconia, zirconium phosphate, magnesia, Magnesium phosphate, calcium oxide.

A further development through the use of nanoscale components that are involved in the chemical reaction is in DE 198 12 577 C1 and EP 0 842 967 A3 described. The nanoscale components are based on silanes or silicates. The processing of the very fine dusty and reactive components is in EP 1 082 273 B1 described. The compounds, which are based exclusively on nanoscale components, are then so strongly cross-linked that they are boil-proof and hard, but extremely brittle and completely inflexible. As a result, cracks spread quickly and uninhibited, which in turn damages the joints and adhesive layers involving inorganic binders.

There Adhesives despite their large size Meaning of The modern technology is still classified as "excipients" is, until now also their fracture-mechanical behavior still too little appreciated. While are the possibilities Crack propagation in solids known, as well as some mitigation attempts, however, there is no teaching yet which crack stop mechanisms for mechanical To use claimed layers of inorganic adhesives are. Various metallic and non-metallic additives for cements, Ceramics and inorganic binders or adhesives have been for a while in use. However, they serve only as fillers and sealants or for the improvement the heat and the electrical conductivity.

task In contrast, the present invention is a multicomponent Present binders of the type described above, the one higher flexibility and has improved strength than previous binders. About that It is also an object of the invention a more resistant composite system propose.

These Task is inventively characterized solved, that as third component a metal powder with a medium Particle size ≦ 10 microns provided which has soft metal properties. The soft metal properties of the metal powder at least in the field of application to be generated by means of the binder Ensures bonding layer be. In particular, materials with Brinell hardnesses of 3 to 39 are HB 5 / 31,2 / 15 and / or 6 to 78 HB 5 / 62.5 / 15 and / or 11 to 158 HB 5/125/15 and / or 22 to about 100 HB 2.5 / 62.5 / 15 (according to DIN 50 351) as metal powder for the binder according to the invention suitable.

When processing the binder according to the invention, crosslinking of the particles takes place of the inorganic nanofine powder of the first component. The third component particles pass through the cured binder layer as the finest deposits without forming strong bonds with the other components, resulting in a solidified rigid inorganic polymer block of crosslinked particles of the first component, rather than a space framework containing metal powder deposits with stress-balancing and damping effects are located. These stress-balancing and damping effects are due to the soft-metal properties of the third component. Such a framework has a higher flexibility than a through-hardened compact block, as known from the prior art. The binder according to the invention thus enables the production of more flexible and thus more resistant connecting layers.

The Metal powder of the third component is preferably in nanofine shape and has an average particle size ≦ 1 micron. By the The use of such a nano-fine metal powder can also be used abrasive effect on the devices at machine processing.

Especially It is therefore advantageous if the metal powder of the third component an average particle size ≦ 700nm, preferably between 100nm and 500nm.

As well it is advantageous if the first component has a mean particle size of 700nm, preferably between 100nm and 500nm. Binder with Such small powder particles can be easily with the help of fine nozzles Instruct.

at a particularly preferred embodiment the binder according to the invention contains the third component zinc powder.

Additionally or instead, the third component may be a soft metal powder, especially aluminum and / or copper and / or lead and / or magnesium and / or tin and / or their ductile alloys with Brinell hardness 3 to 39 HB 5 / 31,2 / 15 and / or 6 to 78 HB 5 / 62.5 / 15 and / or 11 to 158 HB 5/125/15 and / or 22 up to approx. 100 HB 2.5 / 62.5 / 15 (according to DIN 50 351). These materials are soft metals and are therefore suitable as damping deposits in one Link layer.

A sees further advantageous embodiment that the third component contains a metal powder, the during curing of the binder chemically foams. In this way, cavities created, which in turn becomes a skeletal structure of networked Particles of the first component leads. The resulting cavities within the tie layer act as crack stop points. A such compound layer has over those of the prior art Known tie layers a higher flexibility and a low density.

at such a binder, the third component preferably contains Lithium and / or sodium and / or calcium.

to increase the electrical and / or thermal conductivity the connection layer to be created may be advantageous if the third component is precious metal powder, in particular silver powder contains. About that In addition, the reactivity of the third component can also be reduced hereby become.

The The invention also relates to a composite system with two over one cured inorganic compound layer connected components, wherein the tie layer by means of a previously described binder is made.

at the composite system according to the invention is the cured one Connecting layer preferably in the form of a scaffold crosslinked inorganic nanoparticles is formed, wherein the framework Metal powder inclusions surrounds. The scaffolding has a supporting function and consists of particles of the first Component. The Metallpulvereinschlüsse act as a support body for the framework mechanically dampening and remove voltage spikes within the interconnect layer. Through the metal powder connections, which are present as fine to nano-platinum storage, the framework is flexible and increased thus the flexibility the connection layer. About that In addition, the cracking and propagation is inhibited. The danger the formation of notch stresses by the enclosed metal particles is negligible at least for micro- to nanofine metal inclusions.

Especially It is advantageous if the thermal expansion coefficient the metal powder connections greater than the thermal expansion coefficient of the material of the scaffold is. In this case, by heating the metal powder shells a Built internal pressure in the connecting layer and the adhesive bond, with which the components are connected to be dissolved non-destructively.

In a preferred embodiment of the composite system according to the invention, the proportion of the metal powder within the connecting layer is at least 10% by weight, preferably at least 30% by weight. This results in a significant improvement in electrical conductivity and thermal conductivity for a variety of adhesive technical applications, eg for antistatic effects.

Furthermore is a method for producing an inorganic compound layer in a composite system according to the invention by means of a binder according to the invention advantageous in which the first component of the binder before the second component is mixed with the third component is added, after adding the third component by adding the second component chemical crosslinking of the inorganic nanoparticles is used, wherein the inorganic nanoparticles begin to form a flexible space frame and the mixture of first, second and third components Completion of the chemical crosslinking to the inorganic compound layer is processed. The metal powder particles are thereby in the composite the crosslinking nanoparticles of the first component of the binder according to the invention stored.

It is particularly advantageous if cleavage products formed during chemical crosslinking during the addition of the second component of the binder to the first and third components are bound by the metal powder inclusions. By bonding the cleavage products, such as H ₂ O, it is avoided that these cleavage products escape, thus creating a shrinkage within the bonding layer. Likewise, the formation of gas bubbles is prevented. In this way, a defined density of the connecting layer is ensured and the penetration of foreign substances into the layer is made more difficult.

at a particularly advantageous variant of the method are the Metal powder connections to accelerated curing the connection layer by applying an alternating electromagnetic field heated. Required at room temperature the chemical crosslinking reaction between 24 hours and more Weeks to the mechanical-physical end values of a bond or a compact body to reach from the inorganic binder. In addition, comes it, with conventional hardening with heat from the outside inward, especially with thicker layers due to the resulting temperature gradient and the expansion difference often leads to thermal stress with the danger the cracking. By a warming the bonding layer from the inside over the metal inclusions this can be prevented.

For this will be the metal powder shells preferably to a temperature between 100 ° C and Heated to 300 ° C.

at a particularly preferred variant of the method are the first and the third component is vacuum packed separately until mixed in front. Functional impairments such as unwanted Agglomeration of the particles of the first component and their chemical Change, can restricted or be completely stopped.

Advantageous is also a method for solving a by means of a multicomponent according to the invention Binder produced adhesive bond in a composite system according to the invention, the metal powder shells in the adhesive bond by applying an alternating electromagnetic field be heated so much that it is due to the different thermal expansion of the inorganic space frame and the metal powder shots to mechanical stresses resulting in a decay the bindings of the space frame comes. That way you can Adhesive joints of fragile components, such as made of ceramic, to be released again without damage. This can e.g. for repair purposes in the increasing and so far connection problematic Use of ceramic in motor construction may be useful.

in this connection For example, the metal powder shots are preferable to a temperature between 300 ° C and Heated to 1000 ° C.

Further Advantages of the invention will become apparent from the description and the Drawing. Likewise the above-mentioned and the further listed features per se or can be used for several in any combination. The shown and described embodiments not as final enumeration but rather have exemplary character for the description the invention.

It demonstrate:

1 a section of a space frame of a polymer of inorganic fine powder of a binder according to the invention by incorporation of metal powder resulting polymer block;

2 a section of an inventive composite system under the action of shear forces;

3a a schematic representation of the crack propagation in a compact body;

3b a schematic representation of the crack propagation in a bonding layer according to the invention; and

4 a reaction scheme of a condensate tion reaction, which leads to the crosslinking of polysilicates of the first component of the binder according to the invention.

The Inventive binders consists of at least three components, with the first component is an inorganic ultrafine powder, which preferably consists of nanoparticles consists. As the first component, e.g. Polysilicates and compounds based on zirconium. These particles of the first component can by Addition of an inorganic or aqueous liquid as reactant, Reaction accelerator or catalyst (second component) below Crosslink release of fission products, resulting in a hardening of the Mixture leads. The second component is reaction-triggering.

Typical for the curing of phosphates and alkali metal silicates are condensation reactions that lead to crosslinking. 4 shows a typical reaction scheme of such condensation reaction with crosslinking of polysilicates. The hardeners used as the second component (often also called "diluents") are based on an aqueous liquid or on a glass of water, which, however, is firmly bound during hardening. This creates the fission product H ₂ O, which promotes blistering and shrinkage and the quality of z. B. may affect adhesive layers.

The mixing ratio of the first component (inorganic powder) to second component (hardener) are in the literature 2 to 3 Parts by weight of inorganic powder to 1 part by weight of hardener recommended. In the case of very fine powders with increased proportions of nanoparticles, the proportion of the hardener can be increased up to 50% without disturbing the stoichiometry, which can be attributed to the greater surface energy and increased reactivity due to the higher surface volume ratio of those particles. This gives you advantages for the processing phase by lower viscosity advantages in terms of a spray and liquid application and less abrasive stress on the device parts.

A such crosslinking reaction leads in the known from the prior art binders to a compact polymer block, which is brittle and inflexible on the one hand and the otherwise exposed to fission by the release of the fission products is. Both make a made by such a binder Bonding layer prone to cracking.

Around to prevent such cracking therefore provides the method before that before the admixture of the hardener (second component) too the inorganic powder (first component) the inorganic powder a third component is admixed in the form of a metal powder. This metal powder is preferably in nanofine form and contains crystalline Soft metal particles or metal particles, which at least at low Long-term stress and small particle rolling soft metal properties having. Among soft metal properties, both the light Formability of the material at low processing pressure as also the creep / flowability of the material at slow stress (small force per time) understood. The Brinell hardness of such metals are generally at 3 to 39 HB 5 / 31,2 / 15 or 6 to 78 HB 5 / 62,5 / 15 or 11 to 158 HB 5/125/15 or 22 to approx. 100 HB 2.5 / 62.5 / 15 (acc DIN 50 351). The materials usable as the third component have to Accordingly, at low or slow stress ductile and flowable. Zinc, for example, has these low-stress properties even if it reacts brittle when exposed to rapid pressure, and is therefore the third component of the binder according to the invention suitable. About that In addition, zinc is also soft in the temperature range of 100 ° C to 150 ° C. Even at temperatures between room temperature and 100 ° C tends zinc for creeping (cold flow), which he especially at particle sizes in the nanometer range gives a soft metal character.

In the method, the particles of the metal powder are incorporated during the crosslinking of the inorganic particles of the first component in the composite of anorgani's particles without entering into bonds with them. A compound layer created in this way 1 is in 1 shown. As a result, there is no through-hardened, rigid inorganic polymer block, but rather a space frame 2 in the form of a skeleton surrounding the metal powder particles of the third component. The metal powder particles form Metallpulvereinschlüsse 3 within the connection layer 1 , which by force on the bonding layer 1 due to their soft metal properties, do not increase the tension on the surrounding framework, but capture and break down voltage peaks. The inorganic nanoparticle space created by the process is more flexible than a compact block of the same material. 2 shows a composite system according to the invention 4 with two through a bonding layer according to the invention 1 connected components 5a . 5b , Through the within the connection layer 1 as a support body stress-balancing and mechanically damping metal powder connections 3 causes an in 2 shown force F no damage to the composite system 4 , but only an elastic deformation of the connecting layer.

In addition to the formation of inorganic space frame 2 the metal powder connections work 3 even as far as the submicroscopic range as crack-stop additives. 3a shows a schematic representation of the crack propagation in a compact body 6 , A crack 7a can become straight through the compact body 6 spread, which results in a rapid crack propagation (motorway effect). 3b shows a section of a connecting layer according to the invention 1 , with a metal powder connection 3 , An on such a metal powder 3 (Crack stop particles) meeting crack 7b must have the metal powder connection 3 revolve, resulting in a longer crack path (roundabout effect) and the propagation of the crack 7b slowed down. The lifetime of the bonding layer according to the invention 1 is therefore increased over conventional tie layers.

When using reactive metal powder shots, it is achieved that the metal powder particles bind the cleavage products formed in the course of curing by polycondensation, here in particular H ₂ O. In this way, an escape of the fission products and an associated loss of material can be prevented. The formation of cracks by shrinkage of the material is thereby minimized. In addition, gas bubble formation in the material can be restricted in this way.

The metal powder particles, for example of zinc, can bind more or less moisture depending on the preceding storage period and type. Their corrosion, even if the lack of CO ₂ leads to "white rust formation" in the interior of the material composite, is unique and irrelevant for the quality, because of the surrounding inorganic framework.

Alternatively, however, it is also conceivable, a material for the Metallpulvereinschlüsse 3 to choose, which chemically foams when curing the binder and thus generates targeted gas bubbles. Particularly reactive soft metals can cause dissociation of H ₂ O molecules by dissociation. This has the consequence that the oxygen forms oxides with the respective metal, while gas bubbles are formed by the released hydrogen. So can be achieved in the curing of the inorganic binder, a foaming, which also prevents the formation of a massive block and leads to a space frame, which is interspersed depending on the metal particle size of nano to micro voids (voids). Such voids work like the metal powder 3 as crack-stop points, as cracks must also circulate them as the metal powder or oxide inclusions, as in 3b shown. Particularly reactive in this context are alkali metals such as sodium, potassium and calcium, but also the light metals such as lithium.

By the incorporation of metal powder particles in the bonding layer according to the invention 1 Both the electrical and the thermal conductivity of the connecting layer 1 to be influenced.

The metal powder connections 3 can be heated with the help of RF fields. By the heat radiation of the metal powder connections 3 into the adjacent inorganic material areas (Raumgerüst 2 ), an effective, rapid hot curing is realized, which is particularly advantageous for thick tie layers, as they tend due to the tensions occurring in the conventional hot curing with supply of heat from the outside tears.

In addition, the Metallpulereinschlüsse can be heated with the technique described above so strong that a blasting of the inorganic polymer skeleton takes place, which also adhesive bonds break-sensitive components, such as ceramic, can be solved without damage. This gentle blasting is possible if the thermal expansion coefficient of the metal inclusions 3 is greater than the thermal expansion coefficient of the cured inorganic compound layer. This is the case, for example, with the use of aluminum powder as the third component (α _Al ~ 24 10 ^-6 K ^-1 ) and a silicate-based inorganic first component (α ~ 3-10 ₁₀ -6 K ^-1 ).

If the binder according to the invention is used at higher operating temperatures, for example in the range from 300 ° C. to 1000 ° C., then soft metals whose melting point (in the case of alloys melting range or eutectics) change from the crystalline to the amorphous state. To what extent nano- to micro-fine metal particles, which only consist of a few lattice cells, follow these principles is not yet known. However, such inclusions, because they are surrounded by the inorganic framework, are likely to behave like metallic glasses (that is, amorphous but stable). Are the metal powder connections 3 In the form of soft metal and / or alkali metal inclusions oxidized by the preceding hardening process with the decomposition or chemical bonding of the cleavage product H ₂ O, so anyway an increase in the temperature resistance to melting is connected. In the case of intended high-temperature use, however, it is recommended that the inorganic space frame 2 and the metal powder shots 3 coordinated so that the smallest possible difference between the two thermal expansion coefficients, so as to ensure low mechanical stresses during heating of the binder. This does not contradict the above-described solubility of the erfindungsge according to the composite system 4 by HF heating of the metal powder shots 3 , because in such a solution process, the heating, in contrast to high operating temperatures, targeted shock-like from the finest heat centers (Metallpulvereinschlüsse 3 ) takes place from the inside to the outside, whereby even with small differences in the thermal expansion coefficient, the different thermal expansion of inorganic space frame 2 and metal powder shots 3 comes to bear and generates high internal tensions.

Next the for retarding the crack propagation Properties of the metal powder deposits according to the invention in an inorganic space frame can the metal powder deposits also for the optical alignment of inorganic Adhesives in the connection of metallic construction parts serve.

In summary let yourself notice that due to the incorporation of metal powder particles and the chemical crosslinking of inorganic nanoparticles of the inventive binder a flexible space frame in which the metal powder shunts are multifunctional, but primary stress-balancing, dampening, crack-stopping, condensate binding and as heat germs for one RF curing Act. The binder according to the invention therefore offers enormous potential for progress compared to organic ones Adhesives, and can help to overcome some hurdles when using for more extensive technical applications, for example in the realization of the fuel-efficient and thereby environmentally friendly ceramic engine in series production, to overcome. The binder according to the invention Can mainly Starting material for Adhesive and sealing purposes.

Next Ceramic technology in engine construction is also an application the binder according to the invention in dentistry for gluing inlays, crowns, bridges etc. conceivable. This should preferably nickel-free and tissue-compatible materials used as components of the binder. Furthermore it is recommended for the treatment of electrosensitive patients the conductivity to keep the metal powder of the third component small.

1

link layer

2

space frame

3

Metal powder inclusions

4

integrated system

5a, 5b

components

6

compact

7a, b

Crack

F

force

Claims (13)

Chemically and / or physically curable or solidifying, multicomponent binder, wherein at least a first component of the binder prior to curing or solidification as an inorganic nanofine powder having an average particle size ≦ 1 micron and a second component of the binder as a reactant for the first Component and / or as a reaction accelerator or catalyst in the form of an inorganic or aqueous liquid, characterized in that the third component is a metal powder having an average particle size of 10 microns is provided which has soft metal properties. Binder according to claim 1, characterized that the metal powder of the third component in Nanofeiner form is present and has an average particle size ≦ 1 micron Binder according to claim 2, characterized that the metal powder of the third component has an average particle size ≦ 700 nm, preferably between 100nm and 500nm. Binder according to one of the preceding claims, characterized characterized in that the first component has a mean particle size of 700nm, preferably between 100nm and 500nm. Binder according to one of the preceding claims, characterized characterized in that the third component contains zinc powder. Binder according to one of the preceding claims, characterized characterized in that the third component is a soft metal powder, in particular aluminum and / or copper and / or lead and / or magnesium and / or tin and / or beryllium. Binder according to one of the preceding claims, characterized characterized in that the third component contains a metal powder, the during curing of the binder chemically foams. Binder according to claim 7, characterized that the third component is lithium and / or sodium and / or calcium contains. Binder according to one of the preceding claims, characterized in that the third component is noble metal powder, in particular silver powder contains. Composite system with two over a cured inorganic Connecting layer connected components, characterized that the bonding layer by means of a binder after a of the preceding claims is made. Composite system according to claim 10, characterized that the hardened Connecting layer in the form of a skeleton of crosslinked inorganic Nanoparticles is formed, wherein the framework surrounds metal powder. Composite system according to claim 11, characterized that the thermal expansion coefficient the metal powder connections greater than the thermal expansion coefficient the material of the scaffolding is. Composite system according to one of the claims 10 to 12, characterized in that the proportion of the metal powder within the tie layer at least 10% by weight, preferably at least 30% by weight.