Hybrid dielectric film for high temperature application

Abstract

A high-temperature insulation assembly for use in high-temperature electrical machines and a method for forming a high-temperature insulation assembly for insulating conducting material in a high-temperature electrical machine. The assembly includes a polymeric film and at least one ceramic coating disposed on the polymeric film. The polymeric film is disposed over conductive wiring or used as a conductor winding insulator for phase separation and slot liner.

Claims

1. A method for forming a high-temperature insulation assembly, comprising: depositing at least one continuous single phase ceramic coating on a polymeric film, wherein the at least one ceramic coating comprises inorganic deposition material and organic deposition material, and the at least one continuous single phase ceramic coating comprises multiple layers of the inorganic deposition material interleaved between multiple layers of the organic deposition material; and disposing the at least one continuous single phase ceramic coating and the polymeric film thereby forming the insulation assembly, wherein the insulation assembly is located proximate a conducting material in an electrical machine.

2. The method of claim 1, wherein the at least one continuous single phase ceramic coating has a thickness in a range between about 1 nanometer and about 10,000 nanometers.

3. The method of claim 1, wherein the at least one ceramic coating comprises one or more from the group comprising silicon nitride, silicon oxide, silicon oxynitride, aluminum oxide, zirconium oxide, silicon carbide, and any combinations thereof.

4. The method of claim 1, wherein depositing comprises chemical-vapor deposition, plasma-enhanced chemical-vapor deposition, radio-frequency plasma-enhanced chemical-vapor deposition, expanding thermal-plasma chemical-vapor deposition, sputtering, reactive sputtering, electron-cyclotron-resonance plasma-enhanced chemical-vapor deposition, inductively coupled plasma-enhanced chemical-vapor deposition, an evaporative process, an atomic layer deposition process, a slurry coating, and combinations thereof.

5. The method of claim 1, wherein the at least one continuous single phase ceramic coating is disposed on both sides of the polymeric film.

6. The method of claim 1, wherein the at least one continuous single phase ceramic coating comprises two or more coatings.

7. The method of claim 6, wherein the coatings are at least one of different materials and different thicknesses.

8. The method of claim 1, wherein the high-temperature insulation assembly operates at temperatures above 220 degrees Celsius.

9. The method of claim 1, wherein the polymeric film comprises polyphenylene oxide, polyphenylene sulfone, polyether sulfone, polyphenylene sulfide, polyimide, aromatic polyimide, aromatic polyester, polyetherimide, polyamideimide, polyetheretherketone, polytetrafluoroethylene, polyvinylidene fluoride, fluorinated ethylene propylene, perfluoroalkoxy, and any combinations thereof.

10. The method of claim 1, wherein the at least one continuous single phase ceramic coating comprises a pair of ceramic coatings, wherein the polymeric film is sandwiched between the pair of the ceramic coatings.

11. The method of claim 1, wherein the at least one continuous single phase ceramic coating comprises silicon nitride; silicon oxide; silicon oxynitride; aluminum oxide; zirconium oxide; combinations of elements of Groups IIA, IIIA, IVA, VA, VIA, VIIA, IB, and IIB; metals of Groups IIIB, IVB, and VB; rare-earth metals; and, any combinations thereof.

12. The method of claim 11, wherein the at least one continuous single phase ceramic coating comprises silicon carbide, organometallic silanes, or forms of ceramic coating after sintering.

Description

DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic depiction of a section of a motor showing various locations where insulation is used.

(2) FIG. 2 is a schematic depiction of an insulation assembly in accordance with an embodiment.

(3) FIG. 3 is a schematic depiction of a ceramic coating in accordance with an embodiment.

(4) FIG. 4 is a transmission electron microscopy image depicting an insulation assembly in accordance with an embodiment.

(5) FIG. 5 is a schematic depiction of a deposition system for forming an insulation assembly in accordance with an embodiment.

(6) FIG. 6 is a schematic depiction of a deposition system for forming an insulation assembly in accordance with an embodiment.

(7) FIG. 7 is a graphical representation exhibiting the thermal stability of a known insulation assembly and insulation assemblies formed in accordance with an embodiment, plotting loss of weight in percentage against temperature for a temperature increase rate of 10 C./minute.

(8) FIG. 8 depicts process steps for forming an insulation assembly about a conducting material in accordance with an embodiment.

DETAILED DESCRIPTION

(9) The present specification provides certain definitions and methods to better define the embodiments and aspects of the system/method and to guide those of ordinary skill in the art in the practice of its fabrication. Provision, or lack of the provision, of a definition for a particular term or phrase is not meant to imply any particular importance, or lack thereof; rather, and unless otherwise noted, terms are to be understood according to conventional usage by those of ordinary skill in the relevant art.

(10) Unless defined otherwise, technical and scientific terms used herein have the same meaning as is commonly understood by one of skill in the art to which this invention belongs. The terms first, second, and the like, as used herein do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. Also, the terms a and an do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item, and the terms front, back, bottom, and/or top, unless otherwise noted, are merely used for convenience of description, and are not limited to any one position or spatial orientation.

(11) The modifier about used in connection with a quantity is inclusive of the stated value and has the meaning dictated by the context (e.g., includes the degree of error associated with measurement of the particular quantity). Reference throughout the specification to one embodiment, another embodiment, an embodiment, and so forth, means that a particular element (e.g., feature, structure, and/or characteristic) described in connection with the embodiment is included in at least one embodiment described herein, and may or may not be present in other embodiments. In addition, it is to be understood that the described inventive features may be combined in any suitable manner in the various embodiments.

(12) As illustrated in FIG. 2, there is shown therein an insulation separator assembly 100. The insulation separator 100 includes a polymeric film 102 sandwiched between first and second ceramic coatings 104a, 104b.

(13) The polymeric film 102 may be formed of one or more of cross-linked polyethylene, polypropylene, polyester, polycarbonate, polyurethane, high heat polymer films such as polyimide, aromatic polyimide, aromatic polyester, polyetherimide, polyamideimide, polyetheretherketone (PEEK), and polytetrafluoroethylene (PTFE). Alternatively, the polymeric film 102 may be formed of any number of other suitable materials, such as, for example, polyphenylene oxide, polyphenylene sulfone, polyether sulfone, polyphenylene sulfide, or other suitable fluoropolymers such as perfluoroalkoxy (PFA), polyvinylidene fluoride (PVDF), fluoroethylene-propylene (FEP), ethylene-tetrafluoroethylene copolymer (ECTFE), and polychlorotrifluoroethylene (PCTFE) to name a few.

(14) Each of the ceramic coatings 104a, 104b may be formed of a single layer or of many layers of the coatings. Further, the ceramic coatings 104a, 104b both may, instead of sandwiching polymeric film 102, be on one side of the polymeric film. The ceramic coatings 104a, 104b each may be formed of one or more inorganic materials. More specifically, the ceramic coatings 104a, 104b each may be formed of silicon nitride; silicon oxide; silicon oxynitride; aluminum oxide; zirconium oxide; combinations of elements of Groups IIA, IIIA, IVA, VA, VIA, VIIA, IB, and IIB; metals of Groups IIIB, IVB, and VB; rare-earth metals; and, any combinations thereof.

(15) Alternatively, the ceramic coatings 104a, 104b each may be formed of one or more organic materials. More specifically, the ceramic coatings 104a, 104b each may be formed of silicon carbide, organometallic silanes, or forms of ceramic coating after sintering.

(16) The ceramic coating 104a may be formed of different materials than the ceramic coating 104b. For example, ceramic coating 104a may be formed of inorganic materials, while the ceramic coating 104b may be formed of organic materials. Alternatively, each of the ceramic coatings 104a, 104b may be formed of different inorganic materials.

(17) An exemplary ceramic coating 104a is shown in FIG. 3. It should be understood that ceramic coating 104b can also be similarly formed. A first coating layer 106 is deposited on the polymeric film 102. The first coating layer 106 may be organic or inorganic in nature. A second coating layer 108 then may be deposited on the first coating layer 106. The second coating layer 108 may be organic or inorganic in nature. In one embodiment, the second coating layer 108 is formed of the same material as the first coating layer 106. In one embodiment, the second coating layer 108 is formed of the same type of material, i.e., organic or inorganic, as the first coating layer 106 but formed of a different material of that type. For example, in one embodiment, the first coating layer 106 is formed of silicon nitride (SiNx, where x is between about 0.6 and 2.0; hereinafter referred to as SiN) and the second coating layer 108 is formed of silicon carbide (SiCx, where x is between about 1.0 and 2.0; hereinafter referred to as SiC).

(18) A third coating layer 110 may be deposited on the second coating layer 108. The third coating layer 110 may be organic or inorganic in nature. In one embodiment, the third coating layer 110 is formed of the same material as the first coating layer 106. In one embodiment, the third coating layer 110 is formed of the same material as the second coating layer 108. In one embodiment, the third coating layer 110 is formed of the same type of material, i.e., organic or inorganic, as the first coating layer 106 but formed of a different material of that type. In one embodiment, the third coating layer 110 is formed of the same type of material as the second coating layer 108 but formed of a different material of that type. In one embodiment, the first coating layer 106 is formed of SiN, the second coating layer 108 is formed of SiC, and the third coating layer 110 is formed of SiN. In one embodiment, the first and second coating layers 106, 108 are formed of SiN and the third coating layer 110 is formed of SiC. In one embodiment, the first coating layer 106 is formed of SiN, the second coating layer 108 is formed of SiC, and the third coating layer 110 is formed of aluminum oxide (Al.sub.2O.sub.3).

(19) A fourth coating layer 112 may be deposited on the third coating layer 110. The fourth coating layer 112 may be organic or inorganic in nature. In one embodiment, the fourth coating layer 112 is formed of the same material as the first coating layer 106, the second coating material 108, and/or the third coating layer 110. In one embodiment, the third coating layer 110 is formed of the same type of material, i.e., organic or inorganic, as the first, second and/or third coating layers 106, 108, 110 but formed of a different material of that type. In one embodiment, the first, second and/or third coating layers 106, 108, 110 are formed of SiN and the fourth coating layer 112 is formed of SiC. In one embodiment, the first, second and third coating layers 106, 108, 110 are formed of SiN and the fourth coating layer 112 is formed of Al.sub.2O.sub.3. In one embodiment, the first coating layer 106 is formed of SiC, the second coating layer 108 is formed of SiN, the third coating layer 110 is formed of SiC, and the fourth coating layer 112 is formed of Al.sub.2O.sub.3.

(20) It is to be understood that these embodiments are merely exemplary in nature and other materials and combinations of materials may be used. For example, it should be understood that the number of coating layers may be greater or less than the four layers depicted in FIG. 3. Further, inorganic materials may be deposited and gradually tuned to process conditions in which organic materials are then deposited.

(21) The ceramic coatings 104a, 104b provide significant improvement in thermal oxidation resistance. Oxygen is a concern in that its presence accelerates degradation as well as affects the size of corona discharges.

(22) The total thickness of the ceramic coatings 104a, 104b is determined upon the composition of the coatings as well as several competing factors, namely heat resistance and flexibility. The thickness, as well as the composition, of the ceramic coatings 104a, 104b has an effect on the heat resistance provided to the polymeric film 102. Providing a graded composition, i.e., a layer of one or several materials overlying a second layer of a different material(s), provides greater heat resistance than providing an ungraded composition of coating layers. Specifically, a graded composition improves adhesion between different materials by eliminating hard interfaces therebetween. Further, the thicker the composition, the greater the heat resistance provided.

(23) However, the thicker the composition, the less flexibility that can be exhibited by the coated electrical component without generating excess stress leading to cracking of the ceramic coatings. One embodiment provides ceramic coatings 104a, 104b that are each in the submicron to nanometer range. One embodiment provides only a single ceramic coating instead of the paired ceramic coatings 104a, 104b.

(24) The ceramic coatings 104a, 104b formed on the polymeric film 102 in the submicron to nanometer range provide a flexible, high heat resistant dielectric shield for protecting electrical components in high voltage and high temperature applications. Through forming a ceramic coating in the submicron to nanometer thickness range, the hybrid ceramic coating and polymer structure overcomes thermal oxidation and corona induced degradation while maintaining film flexibility. Such a structure can be used at temperatures higher than what traditional polymeric materials can survive, as well as at higher voltages and lower pressures, such as found in aviation and higher altitude applications. Such a structure can find utility in various high power density and high voltage applications, such as, for example, winding and film insulations for motors, transformers, generators, down hole electric motors, power electronic boards, and for power and energy capacitors.

(25) Referring now to FIG. 4, there is shown a transmission electron microscopy (TEM) image of an insulation separator assembly 100. The insulation separator 100 includes a ceramic coating 104a disposed on a material 114 adhered to an epoxy material 116. The material 114 may be, for example, a conductive component. The ceramic coating 104a has a thickness C.sub.T, which may be in the submicron to nanometer range. In one embodiment, the thickness C.sub.T is between about ten-thousand nanometers and one nanometer. In one embodiment, the thickness C.sub.T is between about 750 nanometers and 25 nanometers. In one embodiment, the thickness C.sub.T is between about 500 nanometers and 50 nanometers. In one embodiment, the thickness C.sub.T is between about 350 nanometers and 75 nanometers. In one embodiment, the thickness C.sub.T is between about 250 nanometers and 100 nanometers. In one embodiment, the thickness C.sub.T is 10 nanometers or less.

(26) With specific reference to FIG. 5, there is shown a deposition system 200 for depositing a ceramic coating on a polymeric film 102. The deposition system 200 includes a deposition chamber 202, a pair of spools 210, 212 and a deposition assembly 214a, 214b. A gas inlet allows for gas to enter the deposition chamber 202 to allow for deposition of material on the polymeric film 102.

(27) The polymeric film 102 extends from unwinding spool 210 to winding spool 212. The spools 210, 212 provide sufficient tension for the polymeric film 102 as it travels through the deposition chamber 202. Although the spool 210 is termed an unwinding spool and spool 212 is termed a winding spool, it should be understood that the opposite can also be accurate. Furthermore, the spools 210, 212 are configures such that each can rotate in either a clockwise or a counter-clockwise direction. Thus, the spools 210, 212 can move the polymeric film 102 through the deposition chamber 202 in a direction from spool 210 to spool 212 or in an opposite direction. The ability to change the direction of movement of the polymeric film 102 allows for multiple layers of the ceramic coating to be applied to the polymeric film 102 in a continuous manner via a roll-to-roll mechanism. With the change in direction, new material for deposition can be input into the deposition chamber 202, allowing for a graded composition of ceramic coating on the polymeric film 102.

(28) The deposition system 200 may be configured to allow for the continuous deposition of material in a suitable fashion. Embodiments of the deposition system are configured to allow for deposition by way of chemical-vapor deposition (CVD), plasma-enhanced chemical-vapor deposition (PECVD), radio-frequency plasma-enhanced chemical-vapor deposition (RFPECVD), expanding thermal-plasma chemical-vapor deposition (ETPCVD), sputtering, reactive sputtering, electron-cyclotron-resonance plasma-enhanced chemical-vapor deposition (ECRPECVD), inductively coupled plasma-enhanced chemical-vapor deposition (ICPECVD), an evaporative process, an atomic layer deposition process, a slurry coating, or combinations thereof

(29) Referring now to FIG. 6 there is shown a deposition system 300 that includes a deposition chamber 302, a pair of spools 210, 212 and a deposition assembly. The deposition chamber 302 includes a first deposition chamber 302 separated from a second deposition chamber 308 by a baffle 306. The presence of a pair of deposition chambers 302, 308 allows for a graded composition of ceramic material on the polymeric film in a continuous manner. Further, each of the deposition chambers 302, 308 can have different materials being deposited, with the baffle 306 preventing significant cross-contamination between deposition chambers.

(30) It should be appreciated that more than two deposition chambers can be included within a deposition system. For more information on continuous deposition of materials on a film-like component, please see U.S. Pat. No. 7,976,899, issue date Jul. 12, 2011 and owned by a common assignee as the instant patent application. The entire contents of U.S. Pat. No. 7,976,899 is incorporated herein by reference.

(31) Referring now to FIG. 7, there is shown a graphical representation exhibiting the thermal stability of a known insulation assembly and insulation assemblies formed in accordance with an embodiment of the invention. The thermal gravimetric analysis providing the results displayed in FIG. 7 is based upon a temperature increase rate of 10 C./minute.

(32) As temperature increases on a material, there will come a point at which the material begins to exhibit a heat-related degradation that can be measured by percentage of weight lost. Experiments indicate that a percentage of five to 10 weight percent lost in a material used for insulating a conductive component may lead to a shorting out of that conductive component. FIG. 7 exhibits thermal gravimetric analyses of polymeric film without a coating and polymeric film having a ceramic coating in accordance with embodiments of the invention. As shown in FIG. 7, in which the temperature change was at a rate of 10 C./minute, the temperature at which about five weight percent has been lost from the polymeric film without a coating is about 563 C. The temperature at which about 10 weight percent has been lost from the polymeric film without a ceramic coating is about 588 C. The temperature at which about five weight percent has been lost from the polymeric film with a ceramic coating in FIG. 7 is about 575 C. The temperature at which about 10 weight percent has been lost from the polymeric film with a ceramic coating is about 600 C.

(33) With specific reference to FIG. 8, and with general reference to FIGS. 2-6, next will be described a method of forming a flexible, high heat resistant dielectric shield for protecting electrical components in high voltage and high temperature applications. At Step 400, at least one layer of a ceramic material is deposited onto a polymeric film, such as polymeric film 102. Step 400 may be accomplished in either a batch mode or a continuous mode. In a continuous mode, the polymeric film may be extended between a pair of spools and through a deposition chamber, such as deposition chambers 200 and/or 300. The polymeric film can be transmitted through the deposition chamber numerous times to obtain multiple layers of the ceramic coating and to form a graded ceramic coating composition.

(34) Next, at Step 405 the polymeric film is disposed adjacent to a conducting material. The purpose of disposing adjacent to a conducting material is to provide insulation to the conducting material to inhibit shorting of the conducting material in high temperature environments and applications. Further, the ceramic coating provides corona discharge protection.

(35) While the inventions have been described in detail in connection with only a limited number of embodiments, it should be readily understood that the inventions are not limited to such disclosed embodiments. Rather, the inventions can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the inventions. For example, while embodiments have been described in terms that may initially connote singularity, it should be appreciated that multiple components may be utilized. Additionally, while various embodiments of the inventions have been described, it is to be understood that aspects of the inventions may include only some of the described embodiments. Accordingly, the inventions are not to be seen as limited by the foregoing description, but are only limited by the scope of the appended claims.