DE102015116901A1 - Method for producing an insulator plate, insulator plate and electrochemical measuring device - Google Patents

Abstract

In a method for producing an insulator plate (1) comprising a ceramic layer (4) bonded between a first metal layer (2) and a second metal layer (8), in a first adhesive coating step, the first metal layer (2) is bonded to a first one Surface (3) of the ceramic layer (4) is pressed and thereby a pre-interposed first adhesive amount (5) on the first metal layer (2) and the first surface (3) distributed, during a first curing time of the adhesive, the ceramic layer (4) of the first metal layer (2) again separated, so that the adhesive coatings (6, 7) of the first metal layer (2) and the first surface (3) of the ceramic layer (4) each dry, and then the first metal layer (2) back to the first surface (3) of the ceramic layer (4) is pressed. Subsequently, in a second adhesive coating step, the second metal layer (8) is glued in the same way to a second surface (9) opposite the first surface (3) of the ceramic layer (4), and in a subsequent extrusion step, the prepared insulator plate (1) during a squeezing period the adhesive (5, 10) is heated and pressed so that between the first metal layer (2) and the ceramic layer (4) and between the second metal layer (8) and the ceramic layer (4) in each case a proportion of the first amount of adhesive (5) and the second amount of adhesive (10) is pressed out and exits laterally before the adhesive (5, 10) completely cures.

Description

The invention relates to a method for producing an insulator plate for the electrical insulation of a heatable electrochemical measurement sample, wherein the insulator layer has a ceramic layer which is arranged between a first metal layer and a second metal layer, and wherein the two metal layers each with an adhesive with the interposed ceramic layer are glued.

Various electrochemical measuring devices for determining electrochemical properties of an electrically conductive test sample are known, which can be used, for example, in the field of research and development of novel coolants for industrial plants, heating and cooling devices or in the automotive sector. With suitable electrochemical measuring devices and investigations chemical interactions of a fluid with adjacent surfaces of a sample can be investigated. During the investigations, the pressure and the temperature of the fluid, or of the test sample and an electric field should be specified and changed within practically relevant measuring ranges in order to be able to realize practical test conditions as practical as possible.

To carry out a measurement, an optionally pressurized fluid flow is guided along a surface of the test sample. The sample is heat-transmitting connected to a heater, so that the sample can be heated and cooled. The measurement sample is usually used as a first electrode and brought to a first electrical potential. At a distance from the measurement sample, a counter electrode is arranged, at which a second electrical potential and thus a potential difference to the measurement sample can be applied.

In order to be able to specify both an electrical field or a potential difference between the test sample and the counterelectrode during the execution of a measurement and at the same time to be able to specify the temperature of the test sample and possibly modify it, it is necessary for the test sample to be connected to the heating device as well as possible is and at the same time electrically isolated from the heater and the adjacent components of the measuring device is arranged in the measuring device. For this purpose, an insulator plate is arranged between the test sample and the heater, which has the highest possible thermal conductivity and an electrically insulating effect. Since the test sample must be pressed against the heating device, high contact pressures are usually exerted on the insulator plate arranged between the test sample and the heating device.

It has been found that various ceramic materials have advantageous properties and can combine a high thermal conductivity with a likewise high electrical insulation effect. However, most of the ceramic materials are comparatively brittle and not very pressure-resistant, so that when measurements are taken, the insulator plates made of such a ceramic material are often damaged or broken, thereby influencing and possibly distorting the measurement results. In addition, the cost of a frequent replacement of the damaged insulator plates is very high.

Various embodiments of an insulator plate with a ceramic layer are known in practice, which have for improving the electrical or thermal properties and in particular for improving the mechanical stability of the insulator plate with a metal coating or metal plate connected to the ceramic layer.

For example, in WO 2011 065 157 A1 described laminate two metal layers are connected and solidified with an interposed ceramic layer in a complex and costly plasma arc-sintering process. Out EP 661 916 A1 For example, a heat conduction plate is known in which a number of thermally conductive insulator plates are disposed and embedded in an insulator matrix material.

In a likewise consisting of several layers composite material, for example, in DE 10 2005 062 181 A1 described, multiple layers of an electrically insulating material and a thermally conductive ceramic material are bonded together with a suitable adhesive material, wherein the adhesive material comprises nanofibers in a matrix material.

The insulator plates known from the prior art therefore require either elaborately manufactured and expensive components or else a complicated and expensive production process.

It is therefore considered to be an object of the present invention to provide a method for producing an insulator plate so that, if possible, commercially available components can be connected together at low cost and thereby an insulator plate with good electrical and thermal properties can be produced.

This object is achieved in that in a first adhesive coating step, the first metal layer is pressed against a first surface of the ceramic layer and thereby a pre-interposed first adhesive amount is distributed flat on the first metal layer and the first surface, during a first curing time of the adhesive Ceramic layer is separated from the first metal layer again, so that the adhesive coating of the first metal layer and the first surface of the ceramic layer respectively dry, and then the first metal layer is pressed back onto the first surface of the ceramic layer, that in a second adhesive coating step, the second metal layer to a pressed against the first surface of the ceramic layer opposite the second surface and thereby a pre-intermediate therebetween second adhesive amount surface on the second metal layer and the second O. over a second curing time of the adhesive, the ceramic layer is separated from the second metal layer, so that the adhesive coatings of the second metal layer and the second surface of the ceramic layer respectively dry, and then the second metal layer is pressed back onto the second surface of the ceramic layer and in a subsequent extrusion step, heating and preparing the prepared insulator plate during a second curing time of the adhesive such that a portion of the first adhesive amount and the second adhesive amount are pressed out between the first metal layer and the ceramic layer and between the second metal layer and the ceramic layer, respectively and each side exits before the adhesive cures completely. With the method according to the invention, the metal layers arranged on both sides of the ceramic layer can be connected to each other with a very thin adhesive layer over the entire surface and unbreakable. In the first adhesive coating step and the second adhesive coating step, the respective facing surfaces of the first metal layer and the ceramic layer, or the second metal layer and the ceramic layer are completely coated with the adhesive. By re-separation of the layers after a surface distribution of each applied adhesive amount, the full-area and gapless distribution of the adhesive can be checked on the surfaces. In addition, the exposed adhesive coatings dry out quickly, so that after a short first or second curing time, each of the provided with an adhesive coating metal layers and the ceramic layer can be interconnected in the subsequent extrusion step.

In the extrusion step, not only is a high-strength and mechanically strong bond of the two metal layers with the interposed ceramic layer produced, but also reduces the thickness of the two adhesive layers by heating and pressing the adhesive until the amount of adhesive and, consequently, a layer thickness of the adhesive between the Metal layers and the ceramic layer are each reduced to a minimum. At the same time possibly during the compression of the provided with an adhesive coating metal layers and the ceramic layer inevitably produced air inlets are also laterally pressed out and causes a very homogeneous and therefore good heat conducting transition between the ceramic layer and the externally applied and the ceramic layer bonded metal layers.

According to a particularly advantageous embodiment of the inventive concept it is provided that during the Auspressschritts the insulator plate is heated to a Auspresstemperatur of more than 120 degrees Celsius, preferably of more than 160 degrees Celsius and during Auspressdauer the Auspresstemperatur is not exceeded. It has been found that a squeezing temperature of between 130 degrees Celsius and 180 degrees Celsius is particularly advantageous for sufficiently re-liquefying the adhesive which has dried and converted into a rubbery consistency during the first hardening time and the second hardening time in order to compress the insulator plate can be pressed out laterally between the ceramic layer and the adjacent metal layers. Depending on the adhesive used in each case lower or higher Auspresstemperaturen may be appropriate. It is also possible to use a different adhesive for bonding the first metal layer to the ceramic layer than for bonding the ceramic layer to the second metal layer. The metal layers may also consist of the same or different metals or metal-containing compositions, alloys or metal-plastic compounds.

In order to achieve that during the Auspressschritts a sufficient amount of the adhesive can be pressed out laterally and then sufficient solidification and curing of the remaining adhesive, it is provided according to the invention that the Auspressdauer takes more than two hours and preferably more than four hours.

Investigations have shown that during the Auspressschritts a contact pressure of more than 5 bar, preferably more than 10 bar and particularly preferably more than 15 bar on the insulator plate should be applied. By a particularly high contact pressure, the squeezing of the unnecessary amounts of adhesive can be accelerated. At the same time, the risk of mechanical damage to the insulator plate increases during the pressing-out step. In addition, the Auspresstemperatur and Auspressdauer must be specified at a high extrusion pressure within narrowly defined ranges and reliably maintained in order to effect the desired with the manufacturing method of the invention properties and advantages of the insulator plate according to the invention can.

Compared to the Auspressdauer the first curing time and the second curing time may be relatively short and be for example a few minutes to ten or fifteen minutes. The first curing time and the second curing time may be identical. Different adhesives are used for the bonding of the first metal layer and the ceramic layer and for the bonding of the second metal layer to the ceramic layer, so that also differently long curing times may be expedient.

If a longer preparation time can be accepted, the ceramic layer need not be separated from the respectively associated metal layer during the first curing time and the second curing time until the adhesive coating in question has dried.

According to an advantageous embodiment of the inventive idea, it is provided that the first metal layer or the second metal layer is roughened before the first or the second adhesive coating step. On a roughened surface of the metal layers, an adhesive coating applied during the adhesive coating step adheres particularly well. The unevenness of the roughened surfaces of the first metal layer and the second metal layer may be compensated by the adhesive coating. The roughened metal layers each form an uneven and provided with numerous microscopic recesses and depressions surface that can achieve a particularly high adhesion with the adhesive coating.

It is preferably provided that, after complete curing, a layer thickness of the adhesive between the first metal layer and the ceramic layer and between the ceramic layer and the second metal layer is in each case less than 0.1 millimeter. In this case, the layer thickness represents an average value of a distance of the respective metal layer from the ceramic layer. The first metal layer and the second metal layer can touch the ceramic layer of the individual points in the case of an uneven or roughened surface, such that a distance of the metal layers from the ceramic layer through the latter Touch points is given. By means of such a thin layer thickness of the adhesive between the metal layers and the ceramic layer, it can be achieved that heat transfer through the adhesive coating is scarcely impaired and / or diminished, while at the same time a high-strength and mechanically stressable connection of the metal layers to the intermediate ceramic layer is effected. The ceramic layer is protected from excessive stress by the metal layers firmly and permanently bonded to the ceramic layer, so that a risk of damage or breakage of the ceramic layer during the preparation and performance of measurements with an electrochemical measuring device can be significantly reduced.

According to a particularly advantageous embodiment of the inventive concept, it is provided that an epoxy resin adhesive or an initially thin-bodied and hot-curing adhesive which is as heat-resistant as possible is used as the adhesive. It has been found that adhesives which are also used for the attachment of strain gauges on a metal surface or on a deformation body, can also be advantageously used for bonding the metal layers to the ceramic layer. Such adhesives, which may also be referred to as DMS adhesives, are available commercially and inexpensively in various embodiments. The properties of these adhesives have been extensively studied and precisely researched because of their use in the attachment of strain gauges. Two-component adhesives or, for example, by heating, radiation or otherwise activatable adhesives may also be used.

The invention also relates to an insulator plate for an electrochemical measuring device for determining electrochemical properties of an electrically conductive test sample. According to the invention, the insulator plate has a first metal layer and a second metal layer, each adhesively bonded to a ceramic layer therebetween, wherein a layer thickness of an adhesive between the first metal layer and the ceramic layer and between the ceramic layer and the second metal layer is respectively less than zero , 1 millimeter is.

Advantageously, it is provided that the adhesive arranged between the first metal layer and the ceramic layer and that between the second metal layer and the ceramic layer is an epoxy resin adhesive or an initially thin liquid and heat-curing and heat-resistant as possible adhesive.

Advantageously, the insulator plate has been produced by a method described above.

The invention also relates to an electrochemical measuring device for determining electrochemical properties of an electrically conductive test sample and having a counter electrode arranged at a distance to the test sample, wherein the test sample can be arranged on an insulator plate and flowed through by a fluid, and wherein the insulator plate is connected to a heating device is pressed in order to heat with the heater, the insulator plate and arranged on the insulator plate sample. According to the invention, the insulator plate has a first metal layer and a second metal layer, each adhesively bonded to a ceramic layer therebetween, wherein a layer thickness of an adhesive between the first metal layer and the ceramic layer and between the ceramic layer and the second metal layer is respectively less than zero , 1 millimeter is. Such an insulator plate has been advantageously produced by a method described above.

Embodiments of the inventive concept will be explained in more detail below, which are shown by way of example in the drawing. It shows:

1 a schematic sequence of a method according to the invention for producing an insulator plate,

2 a schematic representation of an enlarged area II, the in 1 illustrated insulator plate, and

3 a schematic representation of an electrochemical measuring device for determining the electrochemical properties of an electrically conductive test sample, the one in the 1 and 2 arranged insulator plate is arranged and pressed against a heater.

In 1 schematically is a sequence of a method according to the invention for producing an insulator plate 1 shown. In a first adhesive coating step a), a first metal layer is formed 2 to a first surface 3 a ceramic layer 4 pressed and thereby a pre-interposed first amount of adhesive 5 flat between the first metal layer 2 and the first surface 3 the ceramic layer 4 distributed. After the areal distribution of the first amount of adhesive 5 on the first metal layer 2 and the first surface 3 becomes the ceramic layer 4 from the first metal layer 2 again separated, taking both on the first metal layer 2 as well as on the first surface 3 the ceramic layer 4 in each case a thin, but flat and completely distributed first adhesive coating 6 . 7 remains. During a first curing time b) of about five minutes, the first metal layer 2 at a distance from the ceramic layer 4 stored, leaving the first adhesive coatings 6 . 7 the first metal layer 2 and the first surface 3 the ceramic layer 4 each dry to one in the first adhesive coating 6 . 7 contained solvent is largely evaporated and the first adhesive coatings 6 . 7 each have a rubbery or viscous consistency. Subsequently, the first metal layer 2 back to the first surface 3 the ceramic layer 4 pressed down and the first metal layer 2 with the ceramic layer 4 connected.

In a subsequent working step, which can alternatively also be carried out simultaneously with the first adhesive coating step described above, a second metal coating is produced in a second adhesive coating step c) 8th to a first surface 3 opposite second surface 9 the ceramic layer 4 printed and a pre-intermediate arranged second amount of adhesive 10 thereby flat on the second metal layer 8th and the second surface 9 the ceramic layer 4 distributed. The second metal layer 8th is then returned to the ceramic layer 4 solved, being on both the second metal layer 8th as well as on the second surface 9 the ceramic layer 4 each a second adhesive coating 11 . 12 remain. Also the second metal layer 8th becomes during a second curing time d) of about five minutes from the ceramic layer 4 stored separately and spaced until the second adhesive coatings 11 . 12 the second metal layer 8th and the second surface 9 the ceramic layer 4 each are dried and have a rubbery or viscous consistency.

Finally, the second metal layer 8th back to the second surface 9 the ceramic layer 4 pressed and a laminate-like layer structure e) is formed, from which in a subsequent extrusion step, the insulator plate 1 can be produced.

For this purpose, during a Auspressdauer f) the two metal layers 2 and 8th pressed together and in each case flat to the intermediate ceramic layer 4 pressed. In addition, the compressed insulator plate 1 heated during the Auspressdauer of more than two hours, or of about three hours to a Auspresstemperatur of about 160 degrees Celsius, so that in each case a proportion of the first amount of adhesive 5 and the second amount of adhesive 10 is pressed out and each side between the first metal layer 2 and the ceramic layer 4 and between the ceramic layer 4 and the second metal layer 8th emerges before the adhesive cures completely. During the extrusion step, an extrusion pressure between 5 and 15 bar on the heated insulator plate 1 exerted and the remaining, or not laterally pressed-out portions of the first amount of adhesive 5 and the second amount of adhesive 10 completely harden. The laterally emerging portions of the first amount of adhesive 5 and the second amount of adhesive 10 being deleted.

The insulator plate produced in this way and shown schematically in f) 1 has very thin layer thicknesses of the adhesive 5 between the first metal layer 2 and the ceramic layer 4 and the adhesive 10 between the ceramic layer 4 and the second metal layer 8th each smaller than 0.1 millimeters.

In 2 is a section II in 1f) the insulator plate 1 shown in an enlarged view. The first metal layer 2 and the second metal layer 8th are each on one of the ceramic layer 4 facing surface 13 . 14 roughened and therefore have a rough and uneven surface 13 . 14 on. The adhesive layers of the adhesive 5 and the adhesive 10 each have a very small thickness of less than 0.1 mm, wherein as a thickness in each case over the surfaces 13 . 14 average distance between the surfaces 13 . 14 the metal layers 2 . 8th and the facing surfaces 3 . 9 the ceramic layer 4 referred to as. Through the roughened surfaces 13 . 14 becomes a particularly durable bond and adhesion of the metal layers 2 . 8th on the ceramic layer 4 favored. During the Auspressschritts is by the contact pressure and the heating of the adhesive 5 and 10 causes the thickness of the adhesive layers to be minimized while avoiding unwanted air pockets and pits in the roughened surfaces 13 . 14 be reliably filled. The metal layers 2 and 8th For example, they can be made of aluminum.

In 3 is schematically an electrochemical measuring device 15 with a flow channel section 16 represented, which forms a sample chamber and can be flowed through by a fluid. A test sample 17 forms a section of a sidewall 18 the flow channel section 16 and is from the outside of a heated pressure plate 19 in one by lateral stops 20 Preselected measuring position pressed. Between the pressure plate 19 and the test sample 17 is the insulator plate 1 arranged by the pressure plate 19 pressed against the test sample.

At one of the test sample 17 opposite side wall 21 the flow channel section 16 there is a counter electrode 22 in the flow channel section 16 arranged platinum net 23 whose dimensions to the surface of the opposite measuring sample 17 is adjusted. The counter electrode 22 is via an electrode feed 24 subjected to an electrical potential. Between the counter electrode 22 and the test sample 17 , which is electrically conductive and acts as an electrode, forms an electric field whose field strength can be specified via the electrical potential.

With the electrochemical measuring device 15 An electrochemical measurement can be performed while the measurement sample 17 is heated and the fluid on the surface of the sample 17 flows past. The fluid may be, for example, a coolant.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• WO 2011065157 A1 [0007]
• EP 661916 A1 [0007]
• DE 102005062181 A1 [0008]

Claims (12)

Method for producing an insulator plate ( 1 ) for electrically insulating a heatable electrochemical test sample ( 17 ), wherein the insulator plate ( 1 ) a ceramic layer ( 4 ) between a first metal layer ( 2 ) and a second metal layer ( 8th ) and wherein the two metal layers ( 2 . 8th ) each with an adhesive ( 5 . 10 ) with the ceramic layer ( 4 ), characterized in that in a first adhesive coating step the first metal layer ( 2 ) to a first surface ( 3 ) of the ceramic layer ( 4 ) and thereby a pre-interposed first adhesive amount ( 5 ) flat on the first metal layer ( 2 ) and the first surface ( 3 ) is distributed during a first curing time of the adhesive, the ceramic layer ( 4 ) of the first metal layer ( 2 ) is separated again, so that the adhesive coatings ( 6 . 7 ) of the first metal layer ( 2 ) and the first surface ( 3 ) of the ceramic layer ( 4 ), and then the first metal layer ( 2 ) back to the first surface ( 3 ) of the ceramic layer ( 4 ) is pressed in a second adhesive coating step, the second metal layer ( 8th ) to one of the first surfaces ( 3 ) of the ceramic layer ( 4 ) opposite second surface ( 9 ) and thereby a pre-interposed second adhesive amount ( 10 ) flat on the second metal layer ( 8th ) and the second surface ( 9 ) during a second curing time of the adhesive ( 10 ) the ceramic layer ( 4 ) of the second metal layer ( 8th ) is separated again, so that the adhesive coatings ( 11 . 12 ) of the second metal layer ( 8th ) and the second surface ( 9 ) of the ceramic layer ( 4 ), and then the second metal layer ( 8th ) back to the second surface ( 9 ) of the ceramic layer ( 4 ) is pressed, and that in a subsequent extrusion step, the prepared insulator plate ( 1 ) during a pressing-out period of the adhesive ( 5 . 10 ) is heated and pressed together so that between the first metal layer ( 2 ) and the ceramic layer ( 4 ) and between the second metal layer ( 8th ) and the ceramic layer ( 4 ) a portion of the first amount of adhesive ( 5 ) and the second amount of adhesive ( 10 ) is pressed out and each side exits before the adhesive ( 5 . 10 ) completely cures. A method according to claim 1, characterized in that during the Auspressschritts the insulator plate ( 1 ) is heated to a Auspresstemperatur of more than 120 ° C, preferably of more than 160 ° C and during the Auspressdauer the Auspresstemperatur is not exceeded. A method according to claim 1 or claim 2, characterized in that the Auspressdauer lasts more than 2 hours, preferably more than 4 hours. Method according to one of the preceding claims, characterized in that during the Auspressschritts an extrusion pressure of more than 5 bar, preferably more than 10 bar and particularly preferably more than 15 bar to the insulator plate ( 1 ) is exercised. Method according to one of the preceding claims, characterized in that before the first or second adhesive coating step, the first metal layer ( 2 ) or the second metal layer ( 8th ) is roughened. Method according to one of the preceding claims 1 to 5, characterized in that after complete curing, a layer thickness of the adhesive ( 5 ) between the first metal layer ( 2 ) and the ceramic layer ( 4 ) as well as between the ceramic layer ( 4 ) and the second metal layer ( 8th ) each is less than 0.1 mm. Method according to one of the preceding claims, characterized in that an epoxy resin adhesive or a first low-viscosity and hot-curing and heat-resistant as possible adhesive is used as an adhesive. Isolator plate ( 1 ) for an electrochemical measuring device ( 15 ) for the determination of electrochemical properties of an electrically conductive test sample ( 17 ), characterized in that the insulator plate ( 1 ) a first metal layer ( 2 ) and a second metal layer ( 8th ), each with an interposed ceramic layer ( 4 ), wherein a layer thickness of an adhesive ( 5 . 10 ) between the first metal layer ( 2 ) and the ceramic layer ( 4 ) as well as between the ceramic layer ( 4 ) and the second metal layer ( 8th ) each is less than 0.1 mm. Isolator plate ( 1 ) according to claim 8, characterized in that the adhesive ( 5 . 10 ) is an epoxy adhesive or a first low-viscosity and hot-curing and heat-resistant as possible adhesive. Isolator plate ( 1 ) according to claim 8 or claim 9, characterized in that the insulator plate ( 1 ) is produced by a method according to one of claims 1 to 7. Electrochemical measuring device ( 15 ) for the determination of electrochemical properties of an electrically conductive test sample ( 17 ) with a test sample ( 17 ) and with a distance to the sample ( 17 ) arranged counter electrode ( 22 ), the test sample ( 17 ) on a Isolator plate ( 1 ) and can be flowed through by a fluid, and wherein the insulator plate ( 1 ) is pressed against a heating device in order with the heating device, the insulating plate ( 1 ) and on the insulator plate ( 1 ) arranged sample ( 17 ), characterized in that the insulator plate ( 1 ) a first metal layer ( 2 ) and a second metal layer ( 8th ), each with an interposed ceramic layer ( 4 ), wherein a layer thickness of an adhesive ( 5 . 10 ) between the first metal layer ( 2 ) and the ceramic layer ( 4 ) as well as between the ceramic layer ( 4 ) and the second metal layer ( 8th ) each is less than 0.1 mm. Electrochemical measuring device ( 17 ) according to claim 11, characterized in that the insulator plate ( 1 ) is produced by a method according to one of claims 1 to 7.

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