EP1996748A1

EP1996748A1 - Device and method for electrophoretic deposition with a movable electrode

Info

Publication number: EP1996748A1
Application number: EP07726690A
Authority: EP
Inventors: Thomas Wiest; Rolf Clasen; Stephan Dierkes; Johannes Zeiner
Original assignee: Bego Bremer Goldschlagerei Wilh Herbst GmbH and Co KG
Current assignee: Bego Bremer Goldschlagerei Wilh Herbst GmbH and Co KG
Priority date: 2006-03-07
Filing date: 2007-03-07
Publication date: 2008-12-03
Also published as: DE102006010808A1; JP2009528868A; WO2007101865A1; US20090095629A1; DE102006010808B4

Abstract

It is an object of the present invention to provide a device (101, 201, 301, 401, 501) for producing a moulding (117), in particular a dental moulding (117), by means of electrophoretic deposition of particles (115) from a suspension (113, 213), wherein a predetermined spatial form can be specifically produced in order thereby to achieve production of the moulding (117) that is as close as possible to the final dimensions and contours. The production of the mouldings (117) is also intended to be inexpensive, resource-efficient and allow itself to be carried out quickly and as easily as possible, with good reproducibility of the method being desirable in order to achieve a low reject rate. Proposed for this purpose is a device (101, 201, 301, 401, 501) with a chamber (103, 503) for receiving the suspension (113, 213), a first electrode (105, 405, 905), which is assigned to the chamber (103, 503), a second electrode (107, 207, 307, 407, 807, 907), which is assigned to the chamber (103, 503), a support structure (107, 219, 907), which is assigned to the chamber (103, 503) and on which the particles (115) can be deposited, wherein the support structure (107, 219, 907) is formed by the second electrode (107, 207, 307, 407, 807, 907) and/or a depositing element (219) arranged between the first electrode (105, 405, 905) and the second electrode (107, 207, 307, 407, 807, 907), a voltage source (109, 409) for generating (52) an electric potential difference between the first electrode (105, 405, 905) and the second electrode (107, 207, 307, 407, 807, 907) and a positioning element (111, 111a) for carrying out a relative movement between the first electrode (105, 405, 905) and the support structure (107, 219, 907) along a first predetermined path (627) during the electrophoretic deposition. According to a further aspect, a corresponding system (with a device (101, 201, 301, 401, 501) according to the invention and a suspension (113, 213) of electrophoretically depositable particles (115)), a corresponding method, a computer program for controlling such a device (101, 201, 301, 401, 501) and also a data carrier with such a computer program are to be provided.

Description

Apparatus and method for electrophoretic deposition with a movable electrode

The present invention relates to a device and a method for producing a shaped body, in particular a dental shaped body, by means of electrophoretic deposition of particles from a suspension. The invention also relates to a system having such a device and a suspension of electrophoretically depositable particles, to a computer program for controlling such a device and to a data carrier having such a computer program.

The electrophoretic deposition of particles is a long-established method for the production of ceramic, metal or metal-ceramic components or glass bodies. In recent years, the electrophoretic deposition of particles for the production of ceramic components, in particular in the field of fuel cell development and in the dental industry has become more and more of a focus. Reasons for this are in the possibility to see homogeneous and To produce dense particle packages, in which also the layer thickness is defined adjustable.

In recent years, potential-supported methods (methods in which an electric field is applied to support or accelerate the process) have been established for the production of dental ceramics, since these, in contrast to compression molding methods, permit higher green densities and a higher homogeneity. Thus, shrinkage can be minimized during sintering, which enables production with greater end contour proximity than with diecasting. In addition, due to the homogeneity, the sample shrinks isotropically. The suspensions on which these processes are based offer the advantage that reprocessing and thus reuse is possible after production of the shaped body.

In particular, zirconium oxide has been very well proven as a material for the production of dental ceramics. It has the advantage that in addition to the very good strength of the green body and molded body and a very good translucency is possible, so that this material has the optical properties of a real tooth or this comes very close.

A method for producing a glass body is known from EP 0 200 242 A2 and EP 0 196 717 A1, in which a porous green body is formed from an aqueous suspension having a highly dispersed solids content and this is subsequently cleaned and sintered, the green body being separated by separation the phases of the suspension is prepared by electrophoresis.

From DE 103 19 300 A1 a method for producing a silica glass body is known. In this case, SiO ₂ particles are deposited from an aqueous dispersion on an electrically non-conductive membrane.

DE 103 20 936 A1 discloses a process for producing a ceramic all-green body, in particular for the dental sector, in which ceramic particles are deposited from a suspension on a porous mold. with an electrode inside and an electrode outside the porous form. It is thereby achieved that, when water is used as the dispersant or suspending agent as a result of electrolytic decomposition, gas bubbles occurring are not incorporated into the green body.

From DE 101 20 084 A1 a method is known in which dental moldings are produced by means of electrophoretic deposition on a model. The outer, the model facing away from the surface of the resulting ceramic body is processed under removal of ceramic material.

From DE 100 49 974 A1 it is known to produce a dental ceramic from at least one ceramic powder with the addition of a metallic powder, wherein the green body is preferably produced by an electrophoretic deposition. When sintered under an oxidative atmosphere, the metal is reduced, which serves to compensate for the sintering shrinkage.

DE 100 49 971 A1 discloses a method in which a green body for a dental ceramic is electrodeposited on an electrode, the green body or the suspension from which is deposited containing ceramic fibers and / or nanocrystalline particles.

In "Creation and Optical Property of Microphotonic Crystals by Electrophoretic Deposition Method using Micro-counter Electrode" (J. -I. Hamagami, K. Hasegawa and K. Kanamura, Mat. Res. Soc. Symp. Proc. 797 (2004 ) 151-156) a method is described in which a microelectrode is arranged opposite to a planar electrode in order to allow a localized electrophoretic deposition.

The often cited advantage of electrophoretic deposition to enable homogeneous layers, however, also constitutes a limitation in the known methods. The largely uniform deposition of the particles over the entire electrode or the entire deposition element and overall over the deposited molding has the consequence that the whole deposited moldings having a substantially uniform layer thickness of deposited particles. This uniform layer thickness makes it necessary in the known methods to provide a post-processing of the deposited body, for example by milling, in order to achieve desired differences in the layer thickness in the deposited molded body. Especially in the dental field, it is often necessary or desirable, for example, in crowns to produce moldings with varying wall thickness.

DE 102 51 369 A1 and DE 103 34 437 A1 teach to provide an electrode which is specially shaped and has regions of different conductivity in order to produce a desired spatial form of a deposited green body, that is to say for layers of deposition of different thicknesses. It proves to be disadvantageous that the special shape of the deposition electrode can only be determined empirically. The effect of a given shaping of the deposition electrode in cooperation with regions of different conductivity on the spatial form of the deposited layer is, if at all, only roughly predicted.

Rapid prototyping methods have also become established in the dental sector for the production of small series and for the construction of prototypes and individual structures. Their great advantage lies in their flexibility, since the tool is not only suitable for the production of a specific geometry, but also ensures form flexibility. In most known embodiments, it is assumed that layers (or films) of ceramic powder are fixed in layers in a location-selective manner. The excess, unfixed powders are usually discarded.

A fixation option is the selective laser sintering (SLS), which generates a lot of excess material. This must be reprocessed in complicated steps. In laminated object manufacturing (LOM), in which cut-to-size films having a thickness of approximately 130 μm are laminated together and then sintered, excess material also accumulates, which can not be reprocessed. EP 1 021 997 A2 discloses a method in which dental restorations and dental auxiliary parts are produced by means of laser sintering. In this case, a biocompatible material is selectively irradiated, so that sintering takes place at these points.

From DE 102 19 983 A1 a method is known in which a laser beam is guided selectively over a powder heap of metallic or non-metallic powders, so that a geometry can be built up layer by layer by lowering the already sintered or molten structure. The disadvantage here is that the geometry, in particular an existing predetermined breaking point, must be mechanically reworked.

The result of a successive, mostly layered, sintering remains in relation to the homogeneity of the material compared to a sintered body as a whole, as deposited by means of electrophoresis.

The known methods, in which an (electrophoretic) deposition is used, make it possible to define with sufficient precision a surface of the molded article to be produced, namely the surface of the molded article which bears against the surface of the support structure on which it is deposited. A desired variation of the thickness of the molding and thus a targeted adjustment of the three-dimensional shape of the molding is only very limited and poorly reproducible possible.

Although known rapid prototyping methods make it possible to selectively produce a desired spatial form, in this case, however, the particular homogeneity of the electrophoretic deposition is not achieved. In addition, material losses due to manufacturing waste in the known methods can not be avoided.

It is an object of the present invention to provide an apparatus and a method for producing a shaped body, in particular a dental molded body, by means of electrophoretic deposition of particles from a suspension, wherein a predetermined spatial form targeted can be prepared so as to achieve a production of the molding as close as possible to final dimensions and near net shape. The production of moldings should also be cost-effective, resource-efficient, fast and easy to carry out, with a good reproducibility of the process is desirable to achieve a low reject rate. According to a further aspect, a corresponding system (with a device according to the invention and a suspension of electrophoretically depositable particles), a computer program for controlling such a device and a data carrier with such a computer program are to be specified.

According to the invention for solving the problem, an apparatus for producing a shaped body, in particular a dental molded body by means of electrophoretic deposition of particles from a suspension proposed, with a chamber for receiving the suspension, a first of the chamber associated electrode, a second of the chamber associated electrode, a support structure associated with the chamber, are deposited on the particles, wherein the support structure of the second electrode and / or a disposed between the first electrode and the second electrode deposition element is formed, and a voltage source for generating an electric potential difference between the first Electrode and the second electrode, the device having a positioning element for performing a relative movement between the first electrode and the support structure along a first predetermined path during the electrophoretic deposition.

In addition, the invention relates to a method for producing a shaped body, in particular a dental molded body, by means of electrophoretic deposition of particles from a suspension, comprising the steps of: providing a suspension of electrophoretically depositable particles, generating an electrical potential difference between a first electrode and a second electrode wherein one of the two electrodes is at least partially disposed in the suspension and the other of the two electrodes is in electrical contact with the suspension, and electrophoretic deposition of particles from the suspension on a support structure, wherein the support structure of the second Electrode and / or one arranged between the first electrode and the second electrode Abscheidelement is formed, wherein the first electrode and / or the support structure during the electrophoretic deposition along a predetermined path are moved relative to each other.

The invention also relates to a system for producing a shaped body, in particular a dental molded body, by means of electrophoretic deposition of particles from a suspension, comprising: a device according to the invention for producing a shaped body and a suspension of electrophoretically depositable particles in the chamber of the device, wherein the support structure and the first or the second electrode are arranged in the operating state at least partially in the suspension and the other of said electrodes is at least in electrical contact with the suspension.

The invention also relates to a computer program that causes an inventive device for producing a shaped article by means of electrophoretic separation of particles from a suspension for carrying out a method according to the invention, when the computer program is executed on the device, as well as a data carrier with such a computer program.

The invention is based on the finding that it is possible to maintain the advantages of an electrophoretic deposition and to achieve a specific spatial structure of the deposited layer, if by a relative movement between an electrode and the support structure (to be deposited on the particles) for the electrophoretic deposition relevant electric field is made variable on the support structure. By a predetermined change of the deposition-causing electric field due to the relative movement between the first electrode and the support structure, a molded article can be produced in a simple manner, the geometry of which largely corresponds to a predetermined target geometry. Although a device for positioning an electrode or a support structure is known from DE 103 20 936 A1, the corresponding device differs from the device according to the invention in that the support structure is brought together with an electrode to a predetermined, fixed position, wherein a Voltage source is available only when the electrode arrangement is fixed. DE 103 20 936 A1 does not envisage making a (relative) movement of the support structure during the electrophoresis.

Essential for the invention is the relative movement of the first electrode relative to the support structure. Which element of the device in this case is moved approximately in relation to the chamber or other elements of the entire device is irrelevant. It is possible to move only the first electrode with respect to a support structure fixed in the chamber or even only the support structure with respect to a first electrode fixed relative to the chamber. In addition, both elements, carrier structure and first electrode can be moved relative to one another and at the same time in each case relative to the chamber.

If the carrier structure is formed by a separating element arranged between the first and the second electrode, for example an electrically nonconductive, ion-permeable mold or membrane, this makes it possible to use water-based pensions without the result of an electrolysis of the water at an electrode Gas is incorporated into the deposited layer. Advantageously, a device according to the invention is designed such that, in the case of an electrolytic decomposition of the dispersing medium or suspending agent, water-forming ions as well as all other free ions present in the system can penetrate the separating element and reach the electrode located behind it. The resulting by a recombination gases thus occur at the electrode and not at the location of the deposition (the separation element). In this way, in an especially favorable embodiment of the invention, an aqueous suspension can be used, since the gas bubbles are not incorporated into the separation body, so that no defects occur in the separation body or green body. This is of great advantage especially in the production of dental ceramics. The use of water as a suspending agent is particularly advantageous because high and very high deposition rates can be achieved due to the high dielectric constant of the water, which can shorten the process time.

However, the carrier structure can also be formed in a known manner by the second electrode, wherein the electrode material is also electrically non-conductive materials, for example gypsum, wax or plastic, if a sufficient electrical conductivity of the material is provided by a suitable coating or admixture Electrode is reached.

The shape of the support structure may be flat or contoured. For example, a three-dimensional free-form framework can be constructed on a planar carrier structure. In this case, only one data set is required, which controls the electrode guidance. If a carrier structure with a contoured shape is present, for example a duplicate of a dental master model, areas of different layer thickness can be achieved by a controlled guidance of the relative movement along a predetermined path. The shape of the support structure already gives the inner or outer contour of the green body or shaped body to be produced. A desired shape of the support structure can be produced in a conventional manner, for example by modeling, molding or else a rapid prototyping method.

The material of the electrodes is preferably chemically resistant or inert to the suspensions used. This also applies to the material of the separation element. Preferably, the electrodes consist of a material selected from the group consisting of zinc, titanium, tungsten, tantalum, graphite, noble metal (in particular silver, gold, platinum), electrically conductive plastics and mixtures thereof. Further, the electrodes may have an electrode core coated with the aforementioned materials. The material of the electrode core itself is not of importance if the electrode core is not mixed with the suspensions or liquids used Contact should come. However, if such a contact is provided, the material of the electrode core should also be chemically resistant or inert. Preferably, the electrode materials are selected so that contamination of the deposited molded body is largely avoided.

As a very advantageous embodiment of the invention has been found in which the ceramic particles have a possible round shape.

In addition, the addition of a dispersing aid, preferably tetramethylammonium (TMAH) or hydrochloric acid (HCl) has proven to be advantageous. This makes it easy to set the pH value.

A suspension with a value of the electrical conductivity between δ.81 mS / n and 175 rrtS / crrt is preferred, in particular between 0.1 mS / cm and 75 mS / cm.

An advantage for the drying of the separation body is a so-called supercritical drying. In general, however, the separator can also be easily dried at room temperature. Another special drying method is drying in a saturated atmosphere, since this prevents structure inaccuracies.

The sintering of zirconium oxide-containing dental ceramics produced in accordance with the invention has proved to be advantageous in a zone sintering furnace at temperatures between 1200 ° C. and 1800 ° C., preferably between greater than 1400 ° C. and 1700 ° C. In this case, a speed of 1 to 15 mm / min, in particular 5 to 12 mm / min, preferably 8 mm / min, maintained. Alternatively, the produced green body may be sintered in a vacuum sintering furnace or a chamber sintering furnace. In an advantageous embodiment of the invention, the support structure is formed by a deposition element arranged between the first electrode and the second electrode, wherein the positioning element allows relative movement to take place along a second predetermined path between the second electrode and the first electrode and / or the deposition element.

If not only a relative movement between the first electrode and the separation element but also a further relative movement of the second electrode with respect to the first electrode and / or the separation element is possible, there are additional degrees of freedom in the design of the relative movements of the electrodes and the separation element to each other, There is greater flexibility in the design options. Starting from a relative movement between the first electrode and the deposition element, the device according to this embodiment is designed, for example, to the fact that the second electrode is stationary relative to the first electrode, but is moved relative to the separation element. Another example is relative fixation of the second electrode to the deposition element upon movement of the second electrode with respect to the first electrode. The device may also be configured to allow movement of the second electrode relative to both the deposition element and the first electrode.

In a further preferred embodiment of the invention, the separation element has an ion-permeable membrane, in particular consisting of a material selected from the group consisting of gypsum, polystyrene, polymethyl methacrylate, polyethersulfone and mixtures thereof.

It has been found that in addition to gypsum in particular the said plastics can be advantageously used as a material for the separation element. The deposition element is preferably electrically non-conductive and preferably also has no semiconductive properties. A pore size in the precipitation element in the range from 10 nm to 10 μm, preferably 500 nm, is advantageous 1 micron, more preferably between greater than 60 nm and 1 micron. Moreover, it has been shown to be advantageous if the separating element is wettable by the suspending agent or the other liquids used in Elektrophoresebetrieb. The contact angle between the precipitation element and, for example, water is accordingly advantageously less than 90 °, preferably less than 80 °. If the criteria listed here are met, other materials may also be used for the separator. It has been found that the material of known dialysis hoses is suitable for use in a device according to the invention.

In a further embodiment of the device according to the invention, the carrier structure is formed by a separating element arranged between the first electrode and the second electrode, wherein the chamber has at least two partial chambers separated by the separating element, wherein the first electrode of a first partial chamber and the second electrode of a second partial chamber assigned and at least the first or the second sub-chamber is provided for receiving the suspension.

In a corresponding embodiment of the system according to the invention, the carrier structure is formed by a separating element arranged between the first electrode and the second electrode, wherein the chamber has at least two partial chambers separated by the separating element during operation, the first electrode being a first partial chamber and the second Electrode is associated with a second sub-chamber and at least the first or the second sub-chamber contains the suspension. In particular, it is preferred that the other of the said sub-chambers in the operating state contains an electrically conductive liquid as a compensating liquid. The values of the electrical conductivity of the suspension or of the equalizing liquid are advantageously in each case between 0.001 mS / cm and 175 mS / cm, preferably between 0.1 mS / cm and 75 mS / cm. In addition, it is preferred if the ratio of the electrical conductivity of the suspension to the compensation fluid is in the range from 0.02 to 50, in particular from 0.02 to 1. Are the electrical conductivities of suspension and equalizing fluid the same or substantially the same, Thus, advantageously, an equal or substantially equal distribution of the electric current in suspension and equalizing liquid results with the same or essentially the same current densities in suspension and equalizing liquid.

During operation, the electric field causes the particles in a known manner to migrate in a desired or specific direction, whereby the electrophoretic deposition is achieved. If, in accordance with the invention, a separating element is provided which is arranged between the first electrode and the second electrode, the separable particles are repelled during operation by one of the electrodes and attracted to the other, whereby particles strike the separating element. However, particles located between the attracting electrode and the precipitating element move towards the attracting electrode and in no case will reach the precipitating element, thus they can not be deposited there either. Now, if the chamber divided by the Abscheidelement in at least two sub-chambers in which one of the electrodes is arranged in operation, it is sufficient to provide according to the invention to give in only one sub-chamber a suspension, namely in the sub-chamber whose particles of the assigned electrode are repelled. According to the invention, the chamber can also be divided by a separating element into sub-chambers, which for example has the shape of a cup. In this case, one partial chamber comprises the interior of the beaker and the other partial chamber is formed by the region of the chamber outside the beaker. An example of such a division can be found in DE 103 20 936 A1.

In a preferred embodiment of the invention, one or both of the electrodes are provided with a means for shielding and / or focusing an electric field between the electrodes.

By shielding or bundling the electric field of the electrode or electrodes, a location-selective and targeted deposition of the particles on the support structure can be achieved during operation. Through the shield or Bundling the field built up in operation between the electrodes can be limited to a defined section of the surface of the support structure or the field strength in areas outside this defined section can be reduced to a desired value, so that due to this field arrangement only or substantially only in this Surface cutout particles are deposited. In this way, according to the invention, the surface of the support structure can be coated with the relative movement along the predetermined path, as it were with an "electrophoretic" brush, whereby the strength or thickness of the deposited layer can be adjusted, for example, by the field strength and the residence time The invention can be achieved by varying the deposition-determining parameters due to the local deposition conditions, a local variation of the density of the deposited molded body.

In a particularly advantageous embodiment of the embodiment described above, one or both electrodes are formed from a line element surrounded by a shield, wherein the shield extends further than the line element in the direction of the opposite electrode.

It has been found that by forming at least one electrode with a coaxial shield, a locally narrow electric field can be established. Such a localization could not be achieved in other arrangements for electrophoretic deposition. Thus, according to the invention, a significant improvement of the local separation efficiency and variability of the local deposition conditions is possible.

In a further preferred embodiment of the invention, one or both of the electrodes have a point tip.

The electric field of a point tip is well located. Especially with two opposite electrodes in the form of a point tip, a symmet- generate the electric field, whereby the control of the electrophoretic deposition can be simplified.

In an advantageous embodiment of the invention, one of the electrodes has a point tip and the other of the electrodes has a circular arc-shaped in cross-section surface, preferably a surface in the form of a spherical zone or a spherical cap.

With such an electrode arrangement, it is possible to produce a symmetrical electric field with a largely uniform field distribution. This allows a simplified planning of the movement of the electrode to produce a desired deposition layer or a shaped body with the desired geometry.

In a further advantageous embodiment of the invention, the surfaces of the electrodes each have opposing faces with parallel surface normals.

Such an electrode arrangement allows a generation of a particularly uniform electric field, as is formed, for example, between the electrodes of a plate capacitor. Thus, according to the invention, a particularly controlled deposition can be carried out in a simple manner.

In an advantageous embodiment of the invention, the voltage source is configured to generate a constant or pulsed DC voltage or a constant or pulsed DC voltage superimposed by an AC voltage.

A constant or pulsed DC voltage can be generated in a particularly simple manner. Even a superposition of such a voltage with an AC voltage does not require high equipment requirements. It has been found that with a DC voltage superimposed with an AC voltage An increased deposition density of the shaped body can be achieved. In this case, it is preferred that the result of the superposition does not show sign changes, since otherwise the driving force for the electrophoretic deposition is reversed. It is not necessary for the DC voltage in any case to have a constant value over the entire operating time when carrying out a method according to the invention. A voltage can already be considered constant in this context if the voltage remains constant for a period of at least 10 seconds, preferably at least 1 minute.

According to a further advantageous embodiment of the invention, the device has a third electrode associated with the chamber, wherein the voltage source is configured, a constant or pulsed DC voltage or a constant or pulsed DC voltage superimposed by an AC voltage between the third electrode and the first and / or second To produce elec- trode.

The electrode arrangement of the device according to the invention is thus not limited to only two electrodes. For example, it may be provided to assign one or more further electrodes to the chamber, wherein in operation the field established between the first and two electrodes is superimposed by one or more further fields, the one or more additional electrodes (n) come from. This allows the electrophoretic deposition to be controlled more variably. The above statements on possible and preferred embodiments of the first and second electrodes also apply to a third or further electrodes.

It is particularly preferred if at least one of the possible relative movements comprises a movement in at least two spatial directions, preferably in three spatial directions, and / or a rotation.

A particularly large freedom of design is achieved if the electrodes against one another or an electrode with respect to the support structure a movement tion in at least one plane, better still can perform in space, with rotations of the elements about its own axis and / or relative to another element are possible.

In a further embodiment of the invention, means for arranging the first electrode are provided substantially vertically above or below the second electrode.

Such an embodiment makes it possible for a movement of the particles to be separated in the suspension in the direction of gravitational attraction or against gravity to take place during operation. It has been found that an increased density of the separating body or shaped body can be achieved in a surprising manner with a movement of the particles in the deposition opposite to the gravitational attraction. A possible explanation for this may lie in the fact that in the suspension, in particular in a poorly dispersed suspension, larger agglomerates of the particles can form which, due to gravity, sink downwards independently of the prevailing electric field. If the electrophoretic deposition takes place against the direction of gravity, it is thus preferable to deposit the particles which have not (yet) come together to form agglomerates. On the other hand, by electrophoretic deposition in the direction of gravitational pull, faster layer build-up can be achieved when gravitational force interacts with the electric field.

In one embodiment of the method according to the invention, the first electrode and / or the support structure are moved relative to one another during the electrophoretic deposition so that the local deposition conditions are essentially determined by the relative movement.

In an inhomogeneous field, a variation of the field strength at the surface of the support structure can be achieved not only by a global change of the field due to a changed potential difference, but in a simple manner by a different positioning of the support structure in the field. A Such different positioning is done by a relative movement. In particular, in the case of a bundled or shielded field, specific surface regions of the carrier structure are exposed to the electric field at different times by a relative movement of the carrier structure relative to the corresponding electrode, with (local) electrophoretic deposition of particles taking place as a result of the locally acting electric field.

In an advantageous embodiment of the system according to the invention, the suspension comprises an organic suspending agent (dispersing agent).

An organic suspending agent can be used advantageously in particular when the highest demands are placed on the structurability of the material to be deposited and a high deposition rate is of secondary importance. It has been found that larger field gradients are possible with organic suspending agents compared to aqueous suspensions. This may be due to the lower electrical conductivity of organic liquids. The larger field gradients, i. The use of organic dispersants, allow a more targeted modeling of the Abscheidekörpers. As organic non-aqueous dispersants, for example, ethanol or dielectric liquids (e.g., hydrocarbons) can be used.

In an advantageous embodiment of the system according to the invention, the suspension has water as a suspending agent (dispersing agent).

The use of water as a suspending agent offers the possibility of achieving very high deposition rates, presumably due to a higher dielectric constant compared to organic suspending agents, which shortens the process time and increases the throughput. In this case, deionized water is preferred, in particular distilled water, bidistilled water being particularly preferred. According to the invention, typical deposition rates are in the range from 0.05 mm / min to 10 mm / min, in particular for aqueous suspensions in the range from 0.5 to 2 mm / min. In general, the deposition rate of organic suspending agents is a factor of 10 to 100 lower than in aqueous suspensions.

In the following the invention with reference to preferred embodiments with reference to the accompanying figures will be explained in more detail. They show schematically:

1 shows a device according to the invention in a system for producing a shaped body according to a first aspect of the invention,

2 shows a device according to the invention in a system for producing a shaped body according to a second aspect of the invention,

3 shows a device according to the invention in a system for producing a shaped body according to a third aspect of the invention,

4 shows a device according to the invention in a system for producing a shaped article according to a fourth aspect of the invention,

5 shows a device according to the invention in a system for producing a shaped body according to a fifth aspect of the invention,

6 shows an electrode arrangement according to a sixth aspect of the invention,

7 shows an electrode arrangement according to a seventh aspect of the invention düng,

8 shows an electrode arrangement according to an eighth aspect of the invention, 9 shows an electrode arrangement according to a ninth aspect of the invention and

10 is a flowchart of an embodiment of a method according to the invention.

Corresponding elements are provided in the figures with the same reference numerals, even if they are used in different embodiments.

Fig. 1 shows schematically a device according to the invention in a system for producing a shaped body according to a first aspect of the invention. The device 101 comprises a chamber 103 for receiving a suspension of electrophoretically depositable particles, a first electrode 105 movably arranged in the chamber 103, a stationary second electrode 107 in the chamber as a support structure 107, a voltage source 109 and a positioning element 11 for the first Electrode 105. In the chamber 103 is the suspension 113, which contains electrophoretically depositable particles 115 in an organic solvent. In the schematic representation of FIG. 1, an electrophoretically deposited layer 117 of the particles on the second electrode 107 is already shown. The first and second electrodes 105, 107 are located in the suspension 113 or immerse in it. The system shown in FIG. 1 comprises the device 101 according to the invention and the suspension 1 13.

The wall of the chamber 103 is made of a non-porous, electrically non-conductive, chemically resistant material. In particular, plastics, preferably polycarbonate (PC) and more preferably polymethyl methacrylate (PMMA) are suitable as material for the wall of the chamber 103. Another suitable material is glass.

With the aid of the controllable voltage source 109, a potential difference between the first electrode 105 and the second electrode 107 can be established. the. The resulting electric field (not shown) causes particles 1 15 in the suspension 1 13, to migrate in the direction of the second electrode 107, where these particles then form an electrophoretically deposited layer. The details of the electrophoretic deposition itself and the background to this is not discussed here, since the skilled person is sufficiently familiar with the basic method of electrophoretic deposition. For further details of the electrophoretic deposition, reference is also made to the above cited prior art.

The voltage source is shown here as controllable, but it is also possible to use a DC voltage source for a constant DC voltage or another suitable voltage source. The polarity of the voltage source is important in this context, since an electrophoretic deposition is possible both in the direction of a cathode and in the direction of an anode.

The positioning member 11 1 is configured to allow and control movement of the first electrode 105 along a predetermined path. As indicated in FIG. 1, the first electrode 105 can be moved in the three spatial directions and positioned accordingly by means of the positioning element 11. In addition, a change in the orientation of the electrode 105 by means of the positioning element 11 1 is possible. If, for example, an electrode with a point tip is used, this electrode can be oriented differently in the space, that is to say have a certain orientation. If, in addition, a shield is used in the electrode, the electric field emanating from this electrode first passes from the electrode in a direction determined by the shield, so that it is advantageous to change this direction to the desired one by changing the orientation of the electrode To adjust conditions. A flat plate may also be oriented as an electrode, for example it may turn its surface or an edge to another electrode.

The positioning element is shown in FIG. 1 in the region of the chamber 103 and the suspension 113. However, it is also possible to use the positioning element half of the suspension or to provide outside the chamber, with possibly only the first electrode 105 is in the suspension or immersed in this, but not the positioning. It can also be provided for controlling the positioning element of a separate control unit, for example a computer, by means of which the positioning unit and thus the movement and position of the first electrode can be controlled.

The first electrode 105 has a point tip, which can be guided along the surface of the second electrode 107 contacting the suspension in the desired manner. In this case, both the relative orientation and the distance of the first electrode 105 to the second electrode 107 are determined by the positioning element 11. Since the second electrode is arranged stationary in the chamber (fixing means not shown), a movement of the first electrode 105 readily results in a relative movement between the first electrode 105 and the second electrode 107, which here assumes the function of a carrier structure. The second electrode 107 in the embodiment according to FIG. 1 consists of a plaster model, which has been suitably prepared for use as an electrode. For example, an electrically conductive coating or coating of the model may be provided or in the production of the model an electrically conductive material may have been added in sufficient quantity to the plaster.

If the first electrode 105 is positioned at a certain distance and a certain orientation relative to the second electrode 107, particles 115 are separated from the suspension 113 on the second electrode 107 due to the electric field established between the first and second electrodes 105, 107. Due to the electrode arrangement, this deposition of particles takes place only in a specific area on the second electrode 107 or a layer already deposited on the second electrode 107. If now the first electrode 105 is moved, so also the area in which is deposited, moved over the second electrode. Thus, a large surface area of the second electrode 107 can be gradually covered with a layer of electrophoretically deposited particles, the layer thickness in particular in particular the deposition parameters field strength (in particular on the surface to be deposited) and (electrode) residence time or movement speed depends. The field strength can in this case be adjusted, for example, again via the voltage or via the electrode spacing.

As an alternative to the embodiment shown in FIG. 1, provision may also be made for the second electrode forming the carrier structure to be moved or for both electrodes to be moved.

Fig. 2 shows schematically a device according to the invention in a system for producing a shaped article according to a second aspect of the invention. The device 201 largely corresponds to the device of FIG. 1 described above. The device 201 comprises, like the latter, a chamber 103 for receiving a suspension with electrophoretically depositable particles, a movable first electrode 105 arranged in the chamber 103, a voltage source 109 and a positioning element 11 1 for the first electrode 105. In the chamber 103 is the suspension 213, which contains electrophoretically depositable particles 115 with water as a suspending agent. The first electrode 105 is located in the suspension 213. Contrary to the device described above according to a first aspect of the invention, the device 201 has a separation element 219, which dips into the suspension 213 and divides the chamber 103 into two sub-chambers. The first sub-chamber contains the suspension 213 and the second sub-chamber contains an electrically conductive liquid 221. While the first electrode 105 is disposed in the suspension 213 and thus in the first sub-chamber, the stationary second electrode is in the second sub-chamber and in the electrical Conductive liquid 221. The separation element 219 is made of polyethersulfone and has a pore size in the range of 60nm to 1 micron. In the schematic representation of FIG. 2, an electrophoretically deposited layer 17 of the particles is likewise already shown, which is located here on the outer surface of the separation element 219 facing the suspension 213 or the first electrode 105. The shape of the second electrode 207 is adapted to the shape of the Abscheidelementes 219, but can also be any other shape for the second electrode may be provided. The system shown in FIG. 2 comprises the device 201 according to the invention and the suspension 213 together with the electrically conductive liquid 221.

The difference between the systems shown in FIG. 1 and FIG. 2, apart from the use of water or an organic compound as suspending agent, is that it is intended to deposit not electrophoretically on an electrode itself but on a separating element 219. Thus, it can be avoided that in the case of an electrolytic decomposition of the suspending agent (here: water) resulting gases are incorporated into the deposited layer in the form of gas bubbles, which could result in undesirable defects in the layer structure.

It can be alternatively or additionally provided that the separation element 219 is not arranged stationary as shown in FIG. 2, but that the separation element is arranged to be movable by means of a positioning element. In the case of a movable arrangement of the separating element, it may be possible to dispense with providing the first electrode as movable, since in this way too a relative movement between the first electrode and the separating element can be achieved.

Fig. 3 shows schematically a device according to the invention in a system for producing a shaped body according to a third aspect of the invention. The apparatus 301 largely corresponds to the apparatus of FIG. 2 described above. The apparatus 301 comprises, like those, a chamber 103 for accommodating a suspension with electrophoretically depositable particles, a movable first electrode 105 arranged in the chamber 103, a voltage source 109 and a Positioning element 1 11 a for the first electrode 105. In the chamber 103 is the suspension 213, which contains electrophoretically depositable particles 115 with water as a suspending agent. The first electrode 105 is located in the suspension 213. Differing from the device described above according to a first aspect of the invention and according to the device described above according to a second aspect According to the invention, the device 301 has a separation element 219 which dips into the suspension 213 and divides the chamber 103 into two sub-chambers. The first sub-chamber contains the suspension 213 and the second sub-chamber contains an electrically conductive liquid 221. While the first electrode 105 is arranged in the suspension 213 and thus in the first sub-chamber, the second electrode 307, which deviates from FIG second sub-chamber and in the electrically conductive liquid 221. To enable and control a movement of the second electrode 307, the device 301 has a positioning element 11 1 b. Even if the positioning elements 1 11 a and 1 11 b are shown separately, they can be provided individually as well as combined in a single positioning element 11 1. 3 also shows an electrophoretically deposited layer 117 of the particles, which is located here on the outer surface of the separation element 219 facing the suspension 213 or the first electrode 105. In addition, the device 301 comprises a lid 323, which closes off the chamber 103 and thus prevents impurities from entering the suspension 213 or the electrically conductive liquid 221 from outside the chamber 103. The system shown in Fig. 3 comprises the device 301 according to the invention and the suspension 213 together with the electrically conductive liquid 221. The system shown in Fig. 3 operates in operation similar to that shown in Fig. 2, in the in Fig. 3 illustrated embodiment, in addition, the second electrode is moved.

Fig. 4 shows schematically a device according to the invention in a system for producing a shaped body according to a fourth aspect of the invention. The device 401 comprises a chamber 103, a stationary arranged separating element 219 as a support structure which separates the chamber 103 into a first sub-chamber for receiving a suspension of electrophoretically depositable particles and a second sub-chamber for receiving an electrically conductive liquid, one movably arranged in the first sub-chamber first electrode 405, a stationary second electrode 407 arranged in the second sub-chamber, a third electrode 425 fixedly arranged in the first sub-chamber, a voltage source 409 and a positioning element 11 1 for the first electrode 405. In the first sub-chamber is the suspension 213, which contains electrophoretically depositable particles 15 with water as suspending agent. The first electrode 405 and the third electrode 425 are in the suspension 213 or immerse in this. In the second sub-chamber is the electrically conductive liquid 221. The second electrode 407 immersed in the electrically conductive liquid 221 a.

The first electrode 405 is designed as a flat, plate-shaped electrode which can be moved at a predetermined distance parallel to the likewise flat separating element 219 by means of the positioning element 11. The first electrode 405 is located between the deposition element and the third electrode 425, which is also configured as a flat plate. The area of the third electrode 425 is approximately equal to that of the precipitating element 219, while the area of the first electrode 405 is substantially smaller. The second electrode 407, which, like the third electrode, is configured as a flat plate in a size substantially corresponding to the separating element 219, is located on the side of the separating element 219 opposite the first electrode 405.

The voltage source 409 has partial voltage sources 409a, 409b and 409c. The partial voltage source 409a is a controllable DC voltage source and serves to set up and maintain a DC voltage between the second electrode 407 and the third electrode 425. This DC voltage results in an electric field between the second electrode 407 and the third electrode 425. The partial voltage source 409c is provided to establish and maintain a DC voltage between the first electrode 405 and the second electrode 407. During operation, this DC voltage is superimposed by an AC voltage generated by the partial voltage source 409b. The electric field built up due to the potential difference between the first electrode 405 and the second electrode 407 overlaps with that between the third electrode 425 and the second electrode 407. According to the result of this superposition, electrophoretic deposition of the particles 115 from the suspension 213 occurs on the Separating element 219. By a movement of the first electrode, this deposition can be set differently at different locations of the separation element 219.

The system shown in FIG. 4 comprises the device 401 according to the invention and the suspension 213 together with the electrically conductive liquid 221.

Fig. 5 shows schematically a device according to the invention in a system for producing a shaped body according to a fifth aspect of the invention. The inventive system shown in Fig. 5 with the device 501 according to the invention corresponds largely to that shown in Fig. 4. One difference is that the device 501 is designed so that the chamber 503 is divided by the separating element 219 into an upper and a lower partial chamber. In the present embodiment, the first electrode 405 is disposed vertically below the second electrode 407, whereby in operation, the electrophoretic deposition takes place against a gravitational force on the particles 15. Suitable measures are taken (not shown here) to ensure that the suspension 213 is in contact with the separation element 219 in the desired separation region.

For the sake of clarity, the following exemplary embodiments of electrode arrangements did not depict voltage sources, suspensions or positioning elements.

Fig. 6 shows schematically an electrode arrangement according to a sixth aspect of the invention. A first electrode 105 is movably disposed in the vicinity of a stationary second electrode 107 and has a dot tip. The first electrode 105 or its tip can follow a predetermined path 627, which was chosen here so that it follows the surface contour of the second electrode 107. In addition, the inclination of the first electrode 105 may be changed such that it is aligned, for example, during movement along the path 627 perpendicular to the respective nearest surface element of the surface of the second electrode 107. Fig. 7 schematically shows an electrode arrangement according to a seventh aspect of the invention. A first electrode 105 and a second electrode 307 are movably disposed on opposite sides of a separator 219. The electrodes 105, 307 each have a dot-tip and are arranged to follow a first predetermined path 627 and a second predetermined path 729, respectively. In this case, the orientations of the electrodes can be adapted to extend along an extended line between their tips, it being possible for this line to be perpendicular to the surface of the separating element 219 configured as a thin membrane when passing through the paths 627 and 729, respectively ,

Fig. 8 schematically shows an electrode arrangement according to an eighth aspect of the invention. A planar deposition element 219 is arranged between a movably arranged first electrode 105 with a point tip and a movably arranged second electrode 807. The first electrode 105 and the second electrode 807 are coupled with each other so as to perform a synchronous movement, respectively. The first electrode 105 or the second electrode 807 can therefore each move relative to the deposition element 219, but remains stationary relative to the respective other electrode. The second electrode 807 has an arcuate cross-section toward the first electrode 105, with the tip of the first electrode 105 in the center of the associated circle. In this way, a symmetrical field can be generated between the electrodes.

9 shows schematically an electrode arrangement according to a ninth aspect of the invention. A first electrode 905 is fixedly arranged near a second electrode 907. The first electrode 905 is coaxially shielded and comprises a line element 933 which is surrounded by an insulation 935. The insulation 935 is in turn surrounded by a shielding element 937. The insulation 935 and the shielding element 937 extend further than the conducting element 933 in the direction of the second electrode 907. The shielding element 937 in this case has the potential of the second electrode 907. The second Electrode 907 is provided here as a support structure and has as outer contour a desired inner contour of a manufactured (here: dental) shaped body. The second electrode 907 is movably disposed in all spatial directions and may be inclined with respect to the first electrode 905 so that the electric field occurring between the first electrode 905 and the second electrode 907 in operation is always perpendicular to the surface of the second electrode.

Fig. 10 shows schematically a flowchart of an embodiment of a method according to the invention. First, the suspension of electrophoretically depositable particles is provided (step 50) and generates an electrical potential difference between a first electrode and a second electrode, for example in a system as described above (step 52). This is followed by electrophoretic deposition of particles from the suspension on a support structure (step 54). This support structure may be formed by the second electrode or by a deposition element arranged between the first electrode and the second electrode. At the same time as the electrophoretic deposition (step 54), one of the steps 56 or 62 takes place.

Step 56 is that the first electrode and the support structure are moved relative to each other. In this case, either the first electrode or the carrier structure or both the first electrode and the carrier structure can be moved. In addition to step 56, in embodiments in which a deposition element is provided as a support structure between the first and second electrodes, step 58 and / or step 60 may be performed simultaneously with step 56.

Step 58 is that the first electrode and the second electrode are moved relative to each other. In this case, either the first electrode or the second electrode or both the first and the second electrode can be moved. Step 60 is that the second electrode and the deposition element are moved relative to each other. In this case, either the second electrode or the deposition element or both the second electrode and the deposition element can be moved.

Steps 56 to 60 cover all relative movement possibilities in which relative movement takes place between the first electrode and the support structure. The case of a relative movement between the support structure and the second electrode without a relative movement between the support structure and the first electrode is only apparently not detected, since in such a case the designations of the first and the second electrode are to be exchanged.

Step 62 is to maintain the relative positions of the first electrode and support structure.

The illustrated embodiment of the method according to the invention comprises at least one embodiment of step 56.

At steps 54 and 56 or 62, a repetition of these steps (54-62) may follow until the electrophoretic deposition is complete.

In addition, it can be provided that further steps take place parallel to the electrophoretic deposition, in which, for example, a third electrode is moved.

Further (summary) explanations and exemplary embodiments:

The invention - as described above and below - relates to a method for producing structured ceramic, metallic or metal-ceramic moldings or green bodies, which can be used after suitable sintering, for example in the dental field. Ceramic or metallic particles are produced according to the invention by means of electrophoresis. se (EPD) from a suspension by means of a (relative to the deposition surface) movable electrode or movable electrodes locally deposited, wherein a local structure by a shielding / bundling of the electric field (for example, by the electrode diameter, the electrode spacing or a koaxi- ale shield ) can be adjusted. Guiding the electrode (s) along a support structure (eg, a porous mold / membrane or the counter electrode) is subject to control by data representing the desired configuration of the molded article. Thus, an electrophoretic process for the spatially resolved production of ceramic or metallic moldings or green bodies is available

The formation of the shaped bodies or green bodies takes place according to the invention by electrophoretic deposition of dispersed ceramic and / or metal powders from suspensions onto a carrier. This may be an electrically conductive or conductive base body or an ion-permeable membrane which is arranged between the electrodes. By means of the structure of the carrier but also by the 3-dimensionally movably arranged electrodes, the shape or the locally applied layer thickness of the deposited green body can be determined according to the invention as a function of the locally effective electric field. The local electric field results from the voltage applied to the electrodes, the electrode geometries (diameter, distance), the coaxial shielding (or bundling) and the dielectric properties of the suspension. In a simple embodiment of the invention, a DC voltage is applied between the electrodes. In advantageous embodiments of the invention, the DC voltage can be pulsed or the applied DC voltage U _D c an AC voltage U _A C (U _D C> U _A c) are superimposed.

After the formation of the molded body can be provided to dry it and then to sinter. The separation from the carrier structure can take place before, during or after the drying. By sintering, a sintered or densely sintered body can be produced. Furthermore, can To reduce the porosity and thus also to increase the strength of the shaped body of the moldings are infiltrated with glass, plastic or metal.

The guidance of the electrode or of the electrodes along the support structure can take place in three dimensions, wherein the applied electrical voltage can be varied. For this purpose, a control can be provided by data, which allow the desired configuration of the shaped body endmaßnah.

Whereas in classical electrophoretic deposition only laminar layers are produced whose layer thickness can not be specifically influenced, the (preferably three-dimensional) guidance of an electrode or of electrodes and / or their shielded / bundled / directed electric field can be both build locally different layer thicknesses as well as on a flat surface three-dimensional moldings (similar to a rapid prototyping method).

It is possible to use these electrode configurations for nonaqueous, organic suspensions. These are used advantageously instead of water in particular when the highest demands are placed on the structurability and the high deposition rate is secondary.

By the deposition of the shaped body on a membrane as a separating element, which is spatially separated from the electrodes, and aqueous Sus pensions can be used without having to take into account any gas formation. The decomposition of water into oxygen and hydrogen at the electrodes for UDC> 1, 23 V (decomposition voltage of water) has no influence on the formation of the ceramic or metallic shaped body on the membrane. Aqueous suspensions are very advantageous because they are easy to handle and because of the high dielectric constants of the water high deposition rates are possible.

In the following further embodiments are given: Example 1 :

Into a 300 ml plastic cup was charged 54.72 g bidistilled water. 5.28 g of tetramethylammonium hydroxide (TMAH) was added. 140 g of zirconium oxide (Tosoh Zirconia Powder TZ-8Y) were stirred in with the aid of a commercial dissolver. Accordingly, the suspension prepared in this way had a solids content of 70.0 wt .-%. The pH of the suspension thus prepared was 12.0, the conductivity at 4.08 mS / cm.

The thus prepared electrophoretic suspension used according to the invention. The conductive liquid used was double-distilled water, mixed with 0.96 g TMAH, filled. As the electrodes, a double-shielded cable having an inner diameter of 100 μm was used, in which the inner wire was shorter than the shield. Polyethersulfone (PES) was used as the material for the membrane separator. The applied DC electrical voltage of the Gleichspannungsquel- Ie was 150 V at a distance of the electrodes of 1, 6 cm, applied for a period of 10 min.

Within this time, the electrodes were controlled by a CAM system (FANUC Robot, LR Mate 200 iB) such that a separator body in the form of a cap was formed on the membrane.

After deposition, the green body was demolded from the separator and dried at room temperature for 48 hours. The density of the green body thus produced was determined by means of Archimedes' principle and was 4.76 g / cm ³ . The green body thus produced was sintered at a temperature of 1600 ° C in a zone sintering furnace at a feed rate of 0.8 cm / min. Thereafter, the structure had a density of 6.27 g / cm ³ .

Example 2: Into a 250 ml plastic jar was charged 32.57 g bidistilled water. 7.43 g of tetramethylammonium hydroxide (TMAH) was added. 160 g of Tosoh Zirconia Powder TZ-8Y were stirred in using a commercial dissolver. The suspension prepared in this way accordingly had a solids content of 80.0% by weight. The pH of the suspension thus prepared was 1 1, 8, the conductivity at 5.17 mS / cm.

The device used is shown schematically in FIG. The conductive liquid used was double-distilled water, mixed with 1.43 g of TMAH. The electrodes used were simply shielded cables with an inner diameter of 100 μm. The material used for the precipitation element was polymethyl methacrylate (PMMA).

The applied DC electrical voltage of the DC voltage source was 150 V at a starting distance of the electrodes 2 of 1, 2 cm. The movement of the electrodes was again controlled by a CAM system (FANUC Robot, LR Mate 200 iB). The moldings thus produced were two caps formed on a membrane. In this case, the distance of the electrodes with increasing thickness of the shaped body of initially 1, 2 cm was gradually increased to 2.1 cm.

After the deposition, the green body was released from the porous mold and dried at room temperature for 72 hours. The density of the green body thus produced was determined by the Archimedes principle and was 4.92 g / cm ³ . The green body thus produced was finally sintered at a temperature of 1650 ° C in a zone sintering furnace at a speed of 0.8 cm / min. Thereafter, the structure had a density of 6.15 g / cm ³ .

Example 3:

Into a 300 mL plastic beaker was charged 52.80 g of pure ethanol. 7.2 g of citric acid were added as a stabilizer. 140 g of Tosoh Zirconia Powder TZ-8Y were stirred in using a commercially available dissolver. The Accordingly, the suspension prepared in this way had a solids content of 70.0% by weight and a conductivity of 24.97 μS / cm.

The suspension thus prepared was used in a device according to the invention in a first sub-chamber. The other compartment was filled with bidistilled water, mixed with 1.43 g of citric acid. The electrodes used were double-shielded cables with an inner diameter of 100 μm. As a material for the separation element as a porous form, a commercially available, soaked in bidistilled water dialysis tube was used.

The applied DC electrical voltage of the DC voltage source was 100 V with a starting distance of the electrodes of 1.75 cm. The movement of the electrodes controlled by a CAM system (FANUC Robot, LR Mate 200 iB) was carried out at a speed of 5 mm / s to a molded body thickness of 3 mm and then at a speed of 3.5 mm / s. This produced a zirconia cap.

After deposition, the green body was dried on the porous mold at room temperature for 24 hours. The density of the green body thus produced was determined by the Archimedes principle and was 4.94 g / cm ³ . The green body thus produced was finally sintered at a temperature of 1600 ° C in a zone sintering furnace at a feed rate of 0.8 mm / min. Thereafter, the structure had a density of 6.1 g / cm ³ .

Example 4:

A slip consisting of glycerol and gold particles is produced and placed in a container. This slip is stabilized with uric acid. As a deposition electrode of the positive impression (working model) of a tooth stump is used. The stump material is a phosphate-bound mass. The surface is made conductive with graphite conductive paint. For this purpose, the surface is first uniformly coated with a conductive paint by means of a brush and then dried at 170 ° C. This conductive model is contacted and placed in the slurry filled container. In this container are both a large-area counter electrode and a controllable / movable counter electrode. It is a double-shielded cable with an inside diameter of 100 μm. A DC voltage of 10 V is applied between the deposition electrode and the counterelectrode and between the deposition electrode and the movable counterelectrode. During the two-minute deposition time, the controllable electrode is moved. This could be used to build thicker layers or anatomical shapes.

The framework thus produced is sintered together with the model in the oven at 900 ° C for 2 hours. The scaffolding on the model sinters and the pores disappear. After sintering, the model is dissolved out of the framework with nitric acid.

Claims

Claims:

1. Device (101, 201, 301, 401, 501) for producing a shaped body (1 17), in particular a dental molded body (117), by means of electrophoretic deposition of particles (115) from a suspension (1 13, 213) , comprising: - a chamber (103, 503) for receiving the suspension (1 13, 213), a first electrode (105, 405, 905) associated with the chamber (103, 503), a second one of the chamber (103, 503) associated electrode (107, 207, 307, 407, 807, 907), - one of the chamber (103, 503) associated support structure (107, 219, 907) are deposited on the particles (115), wherein the support structure (107, 219, 907) from the second electrode (107, 207, 307, 407, 807, 907) and / or between the first electrode (105, 405, 905) and the second electrode (107, 207, 307, 407, 807 906) is formed, and - a voltage source (109, 409) for generating an electric potential difference between the first electrode (105, 405, 905) and the second electrode (107, 207, 307, 407, 807, 907), characterized by a positioning element (11 1, 11 1a) for carrying out a relative movement between the first electrode (105, 405, 905) and the carrier structure (107, 219, 907) along a first predetermined path (627) during electrophoretic deposition.

The apparatus (101, 201, 301, 401, 501) according to claim 1, wherein the support structure (107, 219, 907) is formed by a between the first electrode (105, 405, 905) and the second electrode (107, 207, 307, 407, 807, 907) and the positioning element (11, 11a) performs a relative movement along a second predetermined path (729) between the second electrode (107, 207, 307, 407 , 807, 907) and the first electrode (105, 405, 905) and / or the separation element (219).

3. A device (101, 201, 301, 401, 501) according to any one of the preceding claims, wherein the separation element (219) has an ion-permeable membrane, in particular consisting of a material selected from the group consisting of gypsum, polystyrene, polymethyl methacrylate, polyethersulfone and their mixtures.

4. Device (101, 201, 301, 401, 501) according to one of the preceding claims, wherein the support structure (107, 219, 907) of a between the first electrode (105, 405, 905) and the second electrode ( 107, 207, 307, 407, 807, 907) arranged separating element (219), wherein the chamber (103,

503) has at least two sub-chambers separated by the separation element (219), the first electrode (105, 405, 905) being associated with a first sub-chamber and the second electrode (107, 207, 307, 407, 807, 907) being associated with a second sub-chamber and at least the first or the second sub-chamber for receiving the suspension (113, 213) is provided.

A device (101, 201, 301, 401, 501) according to any one of the preceding claims, wherein one or both of said electrodes (105, 405, 905, 107, 207, 307, 407, 807, 907) is provided with means (935 , 937) for shielding and / or focusing an electric field between the electrodes (105, 405, 905, 107, 207, 307, 407, 807, 907).

6. Device (101, 201, 301, 401, 501) according to claim 5, wherein one or both electrodes (105, 405, 905, 107, 207, 307, 407, 807, 907) consist of one with a shield (935, 937), wherein the shield (935, 937) extends further than the conducting element (933) towards the opposite electrode.

7. Device (101, 201, 301, 401, 501) according to one of the preceding claims, wherein one or both of the electrodes (105, 405, 905, 107, 207, 307, 407, 807, 907) have a dot tip.

The device (101, 201, 301, 401, 501) according to any one of the preceding claims, wherein one of the electrodes (105, 405, 905, 107, 207, 307, 407, 807, 907) is a point tip and the other of the electrodes (105, 405, 905, 107, 207, 307, 407, 807, 907) have a cross-sectionally circular surface (831), preferably a surface (831) in the form of a spherical zone or a spherical cap.

9. Device (101, 201, 301, 401, 501) according to any one of claims 1 to 6, wherein the surfaces of the electrodes (105, 405, 905, 107, 207, 307, 407, 807, 907) each have opposing faces have parallel surface normals.

10. Device (101, 201, 301, 401, 501) according to one of the preceding claims, wherein the voltage source (109, 409) is designed to generate a constant or pulsed DC voltage or a constant or pulsed DC voltage superimposed by an AC voltage ,

1 1. A device (101, 201, 301, 401, 501) according to any one of the preceding claims, wherein the device (101, 201, 301, 401, 501) has a third electrode (425) associated with the chamber (103, 503) ) and the voltage source (109, 409) is designed, a constant or pulsed DC voltage or a constant or pulsed DC voltage superposed by an AC voltage between the third electrode (425) and the first and / or second electrode (105, 405, 905, 107, 207, 307, 407, 807, 907).

12. Device (101, 201, 301, 401, 501) according to one of the preceding claims, wherein at least one relative movement (627, 729) comprises a movement in at least two spatial directions, preferably in three spatial directions, and / or a rotation.

13. Device (101, 201, 301, 401, 501) according to any one of the preceding claims, wherein means for arranging the first electrode (105, 405, 905) substantially vertically above or below the second electrode (107, 207, 307, 407, 807, 907) are provided.

14. A method for producing a shaped body (117), in particular a dental molded body (117), by means of electrophoretic deposition of particles (115) from a suspension (113, 213), with the steps:

Providing (50) a suspension (113, 213) of electrophoretically depositable particles (115),

Generating (52) an electrical potential difference between a first electrode (105, 405, 905) and a second electrode (107, 207, 307, 407, 807, 907), one of the two electrodes (105, 405, 905, 107, 207, 307, 407, 807, 907) at least partially in the suspension (1 13, 213) is arranged and the other of the two electrodes (105, 405, 905, 107, 207, 307, 407, 807, 907) with the Suspension (113, 213) in electrical contact, and - electrophoretic deposition (54) of particles (15) from the suspension (1, 13, 213) on a support structure (107, 219, 907), wherein the support structure (107, 219, 907) from the second electrode (107, 207, 307, 407, 807, 907) and / or between the first electrode (105, 405, 905) and the second electrode (107, 207, 307, 407, 807 , 906) is formed, characterized in that the first electrode (105, 405, 905) and / or the support structure (107, 219, 907) during the electrophoretic Absc heathens (54) along a predetermined path (627) are moved relative to each other (56, 58, 60).

15. The method of claim 14, wherein the first electrode (105, 405, 905) and / or the support structure (107, 219, 907) during the electrophoretic deposition (54) are moved relative to each other (56, 58, 60), that the local deposition conditions are essentially determined by the relative movement.

16. System for producing a shaped body (1 17), in particular a dental molded body (1 17), by means of electrophoretic deposition of particles (115) from a suspension (113, 213), comprising: a device (101, 201, 301, 401 , 501) for producing a shaped body (1 17) according to one of claims 1 to 13 and a suspension (1 13, 213) of electrophoretically depositable particles (1 15) in the chamber (103, 503) of the device (101, 201 , 301, 401, 501), wherein the support structure (107, 219, 907) and the first or the second electrode (105, 405, 905, 107, 207, 307, 407, 807, 907) in the operating state at least partially in the Suspension (1 13, 213) are arranged and the other of said electrodes (105, 405, 905, 107, 207, 307, 407, 807, 907) with the suspension (113, 213) at least in electrical contact.

17. The system of claim 16, wherein the suspension (1 13) comprises an organic suspending agent.

The system of claim 16, wherein the suspension (213) comprises water as a suspending agent.

A system according to any one of claims 16 to 18, wherein the support structure (107, 219, 907) is formed by a contact between the first electrode (105, 405, 905) and the second electrode (107, 207, 307, 407, 807, 907 ), wherein the chamber (103, 503) in the operating state has at least two partial chambers separated by the separating element (219), wherein the first electrode (105, 405, 905) of a first partial chamber and the second electrode ( 107, 207, 307, 407, 807, 907) associated with the second sub-chamber and at least the first or the second sub-chamber containing the suspension (1 13, 213).

20. The system of claim 19, wherein another of the sub-chambers in the operating state contains an electrically conductive liquid (221).

21 computer program comprising a device (101, 201, 301, 401, 501) for producing a shaped body (117) by means of electrophoretic deposition of particles (115) from a suspension (1 13, 213) according to one of claims 1 to 13 for Execution of a method according to claim 14 or 15 caused when the computer program on the device (101, 201, 301, 401, 501) is executed.

22. A data carrier with a computer program according to claim 21.