CN118119048A

CN118119048A - Planar resistance heater and preparation method and application thereof

Info

Publication number: CN118119048A
Application number: CN202410264648.3A
Authority: CN
Inventors: 斯图赫利亚克·佩特罗; 李洋; 徐睦忠; 刘自刚; 郭瑞·弗拉基米尔; 贝尔德妮科娃·欧乐娜; 列皮丽娜·克谢妮娅; 佩雷申科·斯维亚托斯拉夫
Original assignee: Barton Welding Institute Of National Academy Of Sciences Of Ukraine; China Ukraine Baton Welding Research Institute Foreign Economic Representative Office; Zhejiang Baton Welding Technology Co ltd; Zhejiang Barton Welding Technology Research Institute
Current assignee: Barton Welding Institute Of National Academy Of Sciences Of Ukraine; China Ukraine Baton Welding Research Institute Foreign Economic Representative Office; Zhejiang Baton Welding Technology Co ltd; Zhejiang Barton Welding Technology Research Institute
Priority date: 2024-03-08
Filing date: 2024-03-08
Publication date: 2024-05-31

Abstract

The invention discloses a plane resistance heater, which is in the form of a strip-shaped multilayer coating and covers part of the back surface of an antenna substrate, wherein an aluminum oxide bonding layer, a first epoxy resin insulating layer, a resistance heating element layer, a second epoxy resin insulating layer, a heat insulating layer and an epoxy resin protective layer are sequentially arranged from the bottom layer to the outer layer; the aluminum oxide bonding layer comprises a first aluminum oxide bonding layer and a second aluminum oxide bonding layer from the bottom layer outwards, and is obtained by performing energy-gathering explosion spraying on aluminum oxide powder; the first epoxy resin insulating layer comprises a first insulating layer and a second insulating layer from the bottom surface outwards, the second epoxy resin insulating layer comprises a third insulating layer and a fourth insulating layer, and the second insulating layer and the third insulating layer comprise reinforcing fibers; the resistive heating element layer comprises a resistive heating element. The planar resistance heater can be used for the parabolic antenna, so that the parabolic antenna works under severe weather conditions such as cold, icing and the like, the preparation time of the operation of the parabolic antenna is obviously shortened, and the working efficiency is improved.

Description

Planar resistance heater and preparation method and application thereof

Technical Field

The invention relates to a planar resistance heater and a preparation method and application thereof.

Background

Patent UA 21588U discloses a polymer-based planar resistive heating element comprising a strip of dielectric material and metal sheets on both sides. Parallel slots are made in the foil structure to form the electrical heating conductors. Such planar heaters are characterized by electrical heating elements having advanced surfaces.

The use of such heating elements is effective for snow-melting and anti-icing systems for metallic gutters, maintenance of temperature parameters in technical equipment and greenhouse facilities. The heater may also be used in many industries to heat various products, both in residential and non-residential premises to maintain temperature.

The drawbacks of this device and its method of manufacture, first, are its complexity of manufacture, and second, the presence of large heat losses at the "heater-electrically insulating layer" boundary, a significant temperature gradient, reduces the efficiency of the whole device. Disadvantages also include the difficulty in achieving a sealed enclosure from the external environment during manufacturing under high humidity conditions. The above disadvantages reduce the effectiveness of the heater, resulting in significant limitations in use.

Patent UA 25442U discloses another planar heating element which employs a thin electrically insulating heat transfer layer. The conductive foil is used as an electrical heating element while a dielectric material is used as an electrical insulator. The heating element can heat quickly and uniformly distribute heat flow to the working surface of the product. The disadvantage is that the thin resistive layer generates alternating stresses under the influence of thermal cycling, which leads to the occurrence of stress deformations, so that the electrically insulating layer may lose its integrity. In addition, external mechanical action can also lead to damage to the integrity of the electrically insulating layer. Both of these factors reduce the reliability and efficiency of the heating device.

The patent JH 2745039 discloses a method of manufacturing a planar resistive heater. The heating element is prepared using a conductive element and is placed on an insulating film of polyester material. The heating element is composed of a plurality of layers in the form of strips, which are placed along a substrate and laminated together to form an electrically conductive coating. Drawbacks to this method of manufacturing a planar resistive heater include the need to laminate the components in the device manufacture, the weld preparation after the heating element is assembled and the welding process itself, as well as additional processes for forming the layers. During this operation, the electrical insulation properties of the heater element do not provide a stable electrical breakdown value. This is because it is not possible to control and produce coatings of equal thickness during lamination, which means that different layers have different insulating properties. In this case, the actual electrical insulation strength of the layer is estimated from the minimum thickness value thereof. The above drawbacks reduce the efficiency of manufacturing and use of the heating device.

Patent UA71989U discloses a known method of manufacturing a planar resistive electric heater, comprising the following manufacturing steps: a resistive element based on a penetrable material is prepared and then connected to the resistive element of the conductive metal conductor by means of a wire connection to a power source. A resistive element having an electrically conductive conductor is then formed between the layers of electrically insulating coating. Disadvantages of this solution include the need to use complex equipment during manufacture, the relatively low technical performance of the heater itself, and the low reliability of the heater due to ageing of the thermoplastic polymer material (polyvinyl butyral) during operation. In addition, when forming the conductive coating on the flexible coating film, the integrity of the conductive coating is destroyed during manufacturing and thermal cycling, which limits the power and operational reliability of the electric heater.

Duragina z.a., kovbasyuk t.m., bezpalov s.a., analysis of competitive methods for improving the performance of planar heating element functional layers, "metal physics evolution (ADVANCES IN PHYSICAL meth.), volume 17, pages 29-51, discloses a method of manufacturing a heating element: including spraying the resistive coating onto the dielectric substrate, alternating dielectric and resistive coatings may also be used. Wherein the latter is formed on the basis of a paste-like insulating medium and a conductive material, the binder in which is used on the basis of a glass-ceramic paste. The method for manufacturing the planar thermal resistance element has the advantages that: less (or no need at all) of the expensive metal. A disadvantage of this method of manufacturing a planar resistive heater is the difficulty in controlling the thickness and technique of applying the conductive layer using the ion-plasma spray process. In addition, the heating device has the temperature self-adjusting capability. A minimum temperature difference between the temperature of the heating element during operation and the external environment can be observed.

The invention comprises the following steps:

The invention aims to provide a design and a preparation method of a plane resistance heater which can still ensure operation under icing conditions and can be used for a large-diameter parabolic antenna. The planar resistive heater can be used for large-diameter parabolic antennas and further applied to the industries of deep space communication systems, aviation, mechanical manufacturing, instrument manufacturing, marine transportation and the like.

The technical scheme adopted by the invention is as follows:

The planar resistance heater is in the form of a multilayer coating and covers part of the back surface of an antenna base material, and sequentially comprises an aluminum oxide bonding layer, a first epoxy resin insulating layer, a resistance heating element layer, a second epoxy resin insulating layer, a heat insulating layer and an epoxy resin protective layer from the bottom layer to the outer layer.

Further, the multilayer coating is in a continuous strip shape on the back of the antenna base material, the strip shape can be in various shapes of straight lines, fold lines or bends, and can be distributed on the back of the antenna base body in various shapes, and the preferred shapes are U-shaped, W-shaped, Z-shaped and the like. Generally, the antenna substrate is required to be uniformly distributed on the back surface of the antenna substrate, so that the antenna substrate is uniformly heated.

The width of the multilayer coating is preferably 90 to 130mm, more preferably 100 to 110mm.

Further, the aluminum oxide bonding layer sequentially comprises a first aluminum oxide bonding layer and a second aluminum oxide bonding layer from the bottom layer to the outside, and is obtained by energy-gathering explosion spraying of aluminum oxide powder. The first alumina bonding layer has a porosity of less than 0.5% and the second alumina bonding layer has a porosity of 7-20%.

When the antenna substrate is an aluminum-based material, alumina powder is preferentially selected as a spray material. The first alumina bond layer has high electrical breakdown strength and bond strength due to the crystalline compatibility between the aluminum base and the material of the deposited layer. The first alumina bond layer provides a range of performance characteristics: high adhesion strength (120 MPa) and thermal conductivity.

Further, the first alumina adhesive layer is prepared by spraying alumina (Al ₂O₃) powder with a particle size of 5-15 μm onto the back surface of the antenna substrate by energy-accumulating explosion, and has a thickness of 100-150 μm.

The second aluminum oxide bonding layer is prepared by spraying aluminum oxide powder with the particle size of 60-150 mu m on the surface of the first bonding layer through energy-gathering explosion, and the thickness is 200-250 mu m.

Further, the energy-accumulating explosion spraying process of the first aluminum oxide bonding layer comprises the following steps: the flow rate of propane is 0.5-0.7m ³/h, the flow rate of oxygen is 2.3-2.6m ³/h, the flow rate of air is 0.1-0.3m ³/h, the powder consumption rate is 2.5-3.5kg/h, and the energy-gathering explosion spraying process of the second aluminum oxide bonding layer comprises the following steps: the flow rate of propane is 0.6-0.8m ³/h, the flow rate of oxygen is 3.4-3.6m ³/h, the flow rate of air is 0.1-0.3m ³/h, and the powder consumption rate is 2.5-3.5kg/h.

Further, the bonding strength of the first aluminum oxide bonding layer is up to more than 120 MPa. The second alumina adhesive layer has an adhesive strength of 100MPa or more.

Further, in order to reduce residual stress, in forming the planar resistive heater, the alumina bond layer is not provided on the entire projection of the multilayer coating, and the alumina bond layer includes one or more strips that are arranged at the underlying position of the multilayer coating at discrete intervals.

The strip may be of various shapes, preferably rectangular.

Further, the number of the plurality of strips is more than 2, and the strips are preferably uniformly distributed on the back surface of the antenna substrate, are positioned at the bottom layer position of the multilayer coating, and are distributed at intervals.

Further, the length direction of the strip is parallel to the width direction of the multilayer coating, or perpendicular to the length direction of the multilayer coating.

Further, the width of the strip is t/2 to t, the length is preferably t, and t is the width of the multilayer coating.

Further, the spacing distance between the strips is t-1.5 t.

The first epoxy resin insulating layer, the resistance heating element layer, the second epoxy resin insulating layer, the heat insulation layer and the epoxy resin protective layer are arranged above the aluminum oxide bonding layer and cover the aluminum oxide bonding layer to form a strip-shaped multilayer coating.

The first epoxy resin insulating layer sequentially comprises a first insulating layer and a second insulating layer from the bottom surface to the outside, the second epoxy resin insulating layer sequentially comprises a third insulating layer and a fourth insulating layer from the bottom surface to the outside, and the first insulating layer and the fourth insulating layer comprise an epoxy resin adhesive A and an inorganic filler A; the second insulating layer and the third insulating layer comprise epoxy resin adhesive B, inorganic filler B and reinforcing fibers;

the thickness of the first insulating layer and the fourth insulating layer is 0.1-0.2mm.

The thickness of the second insulating layer and the third insulating layer is 0.2-0.3 mm.

The epoxy resin adhesive A or B generally comprises an epoxy resin matrix, a curing agent, various diluents, solvents and the like, and various commercially available epoxy resin matrixes and commonly used curing agents are suitable for the invention.

Wherein A, B in the epoxy resin adhesive A or B represents the epoxy resin adhesive in different layered structures, which is only used for referring to distinction and has no chemical meaning.

The epoxy resin adhesive A or B has better electrical insulation performance.

Preferably, the epoxy resin matrix may be CYD128, SYD128, ED-20, etc.

The curing agent may be a polyamide curing agent, an aromatic amine curing agent, an aliphatic polyamine curing agent, etc., and in a preferred embodiment, is preferably a curing agent curable at ordinary temperature, such as an aliphatic polyamine curing agent, more preferably one or more of ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, polyethylenepolyamine.

The mass amount of the aliphatic polyamine curing agent is usually 10% of the mass amount of the epoxy resin matrix.

The inorganic filler A or B is an insulating substance, so that the performance parameters of the material can be greatly improved, and the fracture toughness, the bending strength and the like of the material can be improved.

A, B in the inorganic fillers A or B represents inorganic fillers in different lamellar structures, and is used only for distinguishing and has no chemical meaning.

The inorganic filler A or B is one or more of aluminum oxide and zirconium oxide independently.

Preferably, the inorganic filler A is alumina; the inorganic filler B is zirconia.

In a preferred embodiment, the inorganic filler A comprises alumina (Al ₂O₃) having a particle size of 10-20 μm and alumina (Al ₂O₃) having a particle size of 100-120 nm.

In a preferred embodiment, the inorganic filler B comprises chromium oxide (Cr 2O 3) having a particle size of 5-10. Mu.m.

The mass consumption of the inorganic filler A is preferably 10-25% of the mass consumption of the epoxy resin matrix.

In a preferred embodiment, the inorganic filler A comprises alumina (Al ₂O₃) having a particle size of 10-20 μm and alumina (Al ₂O₃) having a particle size of 100-120 nm, wherein the mass ratio of alumina having a particle size of 10-20 μm to alumina having a particle size of 100-120 nm is preferably 10-40:1.

More preferably, the first insulating layer and the fourth insulating layer comprise 100 parts by mass of an epoxy resin matrix, 10 parts by mass of an aliphatic polyamine curing agent, 10 to 20 parts by mass of alumina with a particle size of 10 to 20 mu m, and 0.5 to 1.0 parts by mass of alumina with a particle size of 100 nm.

The mass amount of the inorganic filler B is preferably 25 to 35% of the mass amount of the epoxy resin matrix, more preferably 30 to 35%.

The reinforcing fibers may be various insulating reinforcing fibers, preferably inorganic reinforcing fibers, such as basalt fibers.

The thickness of the reinforcing fibers is preferably 0.2 to 0.3mm.

The reinforcing fiber is soaked in the mixture of the epoxy resin adhesive B and the inorganic filler B.

Before the basalt fiber is used, heat treatment (such as gas burner treatment) is generally required to remove the lubricant used in the fiber manufacturing technology, so as to obtain the lipid-free basalt fiber.

In a preferred embodiment, the second and third insulating layers comprise 100 parts by mass of an epoxy resin matrix, 10 parts by mass of an aliphatic polyamine curing agent, 30 to 35 parts by mass of chromium oxide having a particle size of 5 to 10 μm, and 0.2 to 0.3mm thick lipid-free basalt fiber impregnated in the mixture of the epoxy resin adhesive B and the chromium oxide.

The breakdown voltage of the coating layer of the first insulating layer and the fourth insulating layer per millimeter thickness reaches 80-120kV.

The breakdown voltage of the coating layer of each millimeter of thickness of the second insulating layer and the third insulating layer reaches 20-60kV.

The resistance heating element layer comprises an epoxy resin adhesive C, an inorganic filler C and a resistance heating element, wherein the resistance heating element is soaked in a mixture of the epoxy resin adhesive C and the inorganic filler C.

The epoxy resin adhesive C generally comprises an epoxy resin matrix, a curing agent, various diluents, solvents and the like, and various commercially available epoxy resin matrixes and commonly used curing agents are suitable for the invention.

Wherein C in the epoxy resin adhesive C represents the epoxy resin adhesive in different layered structures, is only used for referring to distinction, and has no chemical meaning.

The epoxy resin adhesive C has better electrical insulation property.

Preferably, the epoxy resin matrix may be CYD128, SYD128, ED-20, etc.

The inorganic filler C is an insulating substance, and is preferably one or more of alumina and zirconia.

Preferably, the inorganic filler C is alumina.

More preferably, the inorganic filler C includes alumina (Al ₂O₃) having a particle size of 10 to 20 μm and alumina (Al ₂O₃) having a particle size of 100 to 120 nm.

The mass usage amount of the inorganic filler C is preferably 10-25% of the mass usage amount of the epoxy resin matrix.

In a preferred embodiment, the inorganic filler C comprises alumina (Al ₂O₃) having a particle size of 10-20 μm and alumina (Al ₂O₃) having a particle size of 100-120 nm, wherein the mass ratio of alumina having a particle size of 10-20 μm to alumina having a particle size of 100-120 nm is preferably 10-40:1.

More preferably, the resistance heating element layer includes 100 parts by mass of an epoxy resin matrix, 10 parts by mass of an aliphatic polyamine curing agent, 10 to 20 parts by mass of alumina having a particle diameter of 10 to 20 μm,0.5 to 1.0 parts by mass of alumina having a particle diameter of 100nm, and a resistance heating element immersed in the above mixture.

In a preferred embodiment, the resistive heating element is carbon fiber.

The carbon fiber is strip-shaped, is the same as the shape of the integral multilayer coating, is generally arranged in various shapes and distributed on the back surface of the antenna matrix, and can be in a preferable shape such as U shape, W shape, Z shape and the like.

The two ends of the carbon fiber are plated with copper, then are connected with an external power supply, and can be connected with the power supply in a welding mode, such as a soft soldering mode.

The resistance of the resistive heating element is preferably 30-60 ohms.

The resistance value can be adjusted by adjusting the geometric dimensions (length and width) of the carbon fiber strip, and the power required by the electric heater is set at a fixed voltage.

The thickness of the resistive heating element is preferably 0.1 to 0.2mm, the width is preferably 90 to 130mm, more preferably 100mm.

The thickness of the resistive heating element layer is preferably 0.1 to 0.2mm.

The heat insulation layer is foamed polymer, and can guide heat flow, insulate heat and improve the efficacy of the electric heater. The insulating layer may reduce the heating time of the working surface, thereby eliminating atmospheric precipitation (including rain, snow, ice, etc.) from the antenna working surface.

The foamed polymer may be polyurethane foam, polystyrene foam, polyolefin foam, etc., preferably polypropylene foam.

The thickness of the heat insulation layer is preferably 4-6 mm.

The epoxy resin protective layer comprises an epoxy resin adhesive D and an inorganic filler D. The epoxy resin protective layer can protect the plane resistance heater, prevent the plane resistance heater from being influenced by ultraviolet radiation, air, rain, snow and fog and the like in the open air environment, maintain the stability of the performance of the heater and prolong the service life.

The thickness of the epoxy resin protective layer is generally 0.1-0.2 mm.

The epoxy resin adhesive D generally comprises an epoxy resin matrix, a curing agent, various diluents, solvents and the like, and various commercially available epoxy resin matrixes and commonly used curing agents are suitable for the invention.

Wherein D in the epoxy resin adhesive D represents the epoxy resin adhesive in different layered structures, and is only used for referring to distinction and has no chemical meaning.

The epoxy resin adhesive D has better electrical insulation property.

Preferably, the epoxy resin matrix may be CYD128, SYD128, ED-20, etc.

The inorganic filler D is an insulating substance, and is preferably one or more of alumina and zirconia.

Preferably, the inorganic filler D is alumina.

More preferably, the inorganic filler D comprises alumina having a particle size of 10 to 20. Mu.m.

The mass consumption of the inorganic filler C is preferably 15-25% of the mass consumption of the epoxy resin matrix.

More preferably, the epoxy resin protective layer comprises 100 parts by mass of an epoxy resin matrix, 10 parts by mass of an aliphatic polyamine curing agent, 15 to 20 parts by mass of alumina with a particle size of 10 to 20 μm.

The invention also provides a preparation method of the planar resistance heater, which comprises the following steps:

(1) Spraying an adhesive layer on the antenna substrate by adopting a cumulative explosion spraying method:

The method comprises the steps of (1) spraying a plurality of strips at intervals in a dispersing way on the back of an antenna base material by using alumina powder with the particle size of 5-15 mu m by using a cumulative explosion spraying method, wherein the thickness of each strip reaches 100-150 mu m, so that a first alumina bonding layer is prepared, and the porosity is less than 0.5%;

Adopting alumina powder with the particle diameter of 60-150 mu m on the surface of the first alumina bonding layer, and spraying the powder to the thickness of 200-250 mu m by utilizing energy-accumulating explosion to prepare a second alumina bonding layer with the porosity of 7-20%;

The energy-collecting explosion spraying uses a combustible mixed gas of propane, oxygen and air, uses a multi-chamber explosion device, wherein the combustible mixed gas is simultaneously supplied in more than two combustion chambers while detonating in a precombustor, and in a main cylindrical combustion chamber, combustion product streams form detonation waves at points where the precombustor and a side annular combustion chamber converge; simultaneously, introducing alumina powder into a cylindrical nozzle which is positioned after the last side annular combustion chamber is converged with the main cylindrical combustion chamber, and accelerating and heating the alumina powder through knocking and shock waves of combustion products emitted from the main cylindrical combustion chamber and the side annular combustion chamber in sequence;

The explosion temperature of the energy-gathering explosion spraying is 3000 ℃, and the speed of the explosion wave can reach 1600-1800 m/s. The melting point of the alumina was 2072 ℃. The dispersed powder particles for spraying are heated to a plastic or liquid state due to interaction with the high Wen Bao bombard product. When the solid state is reached and in contact with the antenna substrate, a contact patch is formed. And then cyclically reciprocating.

The energy-accumulating explosion spraying process of the first aluminum oxide bonding layer comprises the following steps: the flow rate of propane is 0.5-0.7m ³/h, the flow rate of oxygen is 2.3-2.6m ³/h, the flow rate of air is 0.1-0.3m ³/h, the powder consumption rate is 2.5-3.5kg/h, and the energy-gathering explosion spraying process of the second aluminum oxide bonding layer comprises the following steps: propane flow rate is 0.6-0.8m ³/h, oxygen flow rate is 3.4-3.6m ³/h, air flow rate is 0.1-0.3m ³/h, and powder consumption rate is 2.5-3.5kg/h;

Further, the spacing distance between the strips is t-1.5 t.

The antenna substrate may be a parabolic antenna substrate.

(2) Coating a mixture of an epoxy resin adhesive A and an inorganic filler A on the surface of an alumina bonding layer according to the shape of a multi-layer coating, and pressing and curing by using a mould to prepare a first insulating layer with the thickness of 0.1-0.2 mm;

the mould is preferably a mould for flexible membranes.

The mixture of the epoxy resin adhesive A and the inorganic filler A preferably comprises 100 parts by mass of an epoxy resin matrix, 10 parts by mass of an aliphatic polyamine curing agent, 10-20 parts by mass of alumina with the particle size of 10-20 mu m and 0.5-1.0 part by mass of alumina with the particle size of 100 nm;

the mold is used for pressing and curing, the mixture can be completely cured for 20-24 hours, a first insulating layer is obtained, and then the next step is carried out; it is also possible to press the flexible film using a mold for 1 to 1.5 hours to produce a first insulating layer that is not completely cured, and then immediately proceed to the next step.

The mixture of the epoxy resin adhesive A and the inorganic filler A can be coated by a spraying method.

(3) Coating a mixture of an epoxy resin adhesive B and an inorganic filler B on the surface of the first insulating layer, then placing reinforcing fibers in the uncured mixture to infiltrate and infiltrate, and pressing and curing by using a mold to prepare a second insulating layer with the thickness of 0.2-0.3 mm;

The mixture of the epoxy resin adhesive B and the inorganic filler B preferably comprises 100 parts by mass of an epoxy resin matrix, 10 parts by mass of an aliphatic polyamine curing agent and 30-35 parts by mass of chromium oxide with a particle size of 5-10 mu m.

The mold is preferably a mold with a flexible diaphragm;

The mold is used for pressing and curing, the mixture can be completely cured for 20-24 hours, a second insulating layer is obtained after the mixture is completely cured, and then the next step is carried out; or pressing the flexible membrane for 1-1.5 hours by using a mould to prepare a second insulating layer which is not completely solidified, and then immediately carrying out the next step;

The reinforcing fibers are infiltrated in the uncured mixture, are required to be fully infiltrated, and if the reinforcing fibers are present in the uncured place, the uncured mixture can be continuously coated and maintained for 5 to 7 minutes, and then pressed and cured by a die.

The thickness of the second insulating layer is regulated by the thickness of the reinforcing fibres, the thickness of this layer being between 0.2 and 0.3 mm.

The reinforcing fibers are preferably basalt fibers. Before basalt fibers are used, heat treatment (e.g., gas burner treatment) is typically required to remove lubricants used in fiber manufacturing techniques to obtain lipid-free basalt fibers.

The mixture of the epoxy resin adhesive B and the inorganic filler B can be coated by a spraying method.

(4) Coating the mixture of the epoxy resin adhesive C and the inorganic filler C on the surface of the second insulating layer, then placing the resistance heating element in the uncured mixture to infiltrate and infiltrate, and pressing and curing by using a die to prepare a resistance heating element layer with the thickness of 0.1-0.2 mm;

The mixture of the epoxy resin adhesive C and the inorganic filler C preferably comprises 100 parts by mass of an epoxy resin matrix, 10 parts by mass of an aliphatic polyamine curing agent, 10-20 parts by mass of alumina with the particle size of 10-20 mu m and 0.5-1.0 part by mass of alumina with the particle size of 100 nm.

The mixture of the epoxy resin adhesive C and the inorganic filler C can be coated by a spraying method.

The mold is preferably a mold with a flexible diaphragm;

The die is used for pressing and curing, the pressing and curing can be carried out for 20-24 hours, the mixture is completely cured, a resistance heating element layer is obtained, and then the next step is carried out; or pressing the flexible membrane for 1-1.5 hours by using a mould to prepare a resistance heating element layer which is not completely solidified, and then immediately carrying out the next step;

the resistance heating element is a long carbon fiber, the resistance is 30-60 ohms, and the thickness is 0.1-0.2mm;

the two ends of the carbon fiber are plated with copper, can be connected with an external power supply, and can be connected with the power supply in a welding mode.

The resistance heating element is infiltrated in the uncured mixture, needs to be fully infiltrated, if the uncured mixture exists in the place where the uncured mixture is not infiltrated, can be continuously coated, and can be kept for 5-7 minutes, and then can be pressed and cured by using a die.

(5) Preparing a third insulating layer on the surface of the resistance heating element layer according to the method of the step (3);

Wherein, the mixture is pressed and cured by a mould for 20 to 24 hours, and after the mixture is completely cured, a third insulating layer is obtained, and then the next step is carried out; or pressing the flexible membrane for 1-1.5 hours by using a mould to prepare a third insulating layer which is not completely solidified, and then immediately carrying out the next step;

(6) Preparing a fourth insulating layer on the surface of the third insulating layer according to the method of the step (2);

at this time, the mixture is cured by pressing with a mold, preferably for 20 to 24 hours, to thereby completely cure the mixture.

The first insulating layer, the second insulating layer, the resistance heating element layer and the third insulating layer which are coated in the next step without being completely cured before are all completely cured by pressing and curing for 20 to 24 hours when preparing the fourth insulating layer.

(7) Coating foaming polymer on the surface of the fourth insulating layer to prepare a heat insulating layer with the thickness of 4-6 mm;

(8) And (3) coating a mixture of an epoxy resin adhesive D and an inorganic filler D on the surface of the heat insulation layer, and pressing and curing by using a die to obtain the epoxy resin protective layer with the thickness of 0.2-0.3 mm.

The epoxy resin adhesive D and the inorganic filler D preferably comprise 100 parts by mass of an epoxy resin matrix, 10 parts by mass of an aliphatic polyamine curing agent and 15-20 parts by mass of alumina with the particle size of 10-20 mu m.

The mixture of the epoxy resin adhesive D and the inorganic filler D can be coated by a spraying method.

The mold is preferably a mold with a flexible diaphragm; it is generally necessary to press cure the mixture with a mold for 20 to 24 hours to completely cure the mixture.

In the method of the present invention, the epoxy resin adhesive is not completely cured within 1 to 1.5 hours of applying the epoxy resin-coated substrate and the curing agent, and at this time, the next layer is immediately applied, which contributes to the enhancement of the adhesive strength between the layers of the epoxy resin layer (first insulating layer, second insulating layer, resistance heating element layer, third insulating layer, fourth insulating layer).

The planar resistance heater provided by the invention can be used for antennas, particularly parabolic antennas, particularly outdoor large-diameter parabolic antennas, so that the planar resistance heater can work under severe weather conditions such as cold, icing and the like, the preparation time of the operation of the planar resistance heater is obviously shortened, and the working efficiency is improved.

The invention also provides a parabolic antenna comprising a planar resistive heater, which is characterized in that the parabolic antenna is used as a base material, the planar resistive heater is arranged on the back surface, and one or more planar resistive heaters can be arranged;

The planar resistance heater is in a multi-layer coating form and covers part of the back surface of the antenna substrate, and comprises an aluminum oxide bonding layer, a first epoxy resin insulating layer, a resistance heating element layer, a second epoxy resin insulating layer, a heat insulating layer and an epoxy resin protective layer from the bottom layer to the outer layer in sequence;

the multilayer coating is in a strip shape with continuous extension;

The aluminum oxide bonding layer sequentially comprises a first aluminum oxide bonding layer and a second aluminum oxide bonding layer from the bottom layer to the outside, and is obtained by aluminum oxide through energy-gathering explosion spraying; the thickness of the first aluminum oxide bonding layer is 100-150 mu m, the porosity is less than 0.5%, the thickness of the second aluminum oxide bonding layer is 200-250 mu m, and the porosity is 7-20%;

The planar resistance heater and the parabolic antenna comprising the planar resistance heater provided by the invention have the advantages that the preparation method is simple, noble metal is not adopted, the heating efficiency is high, the thermal deformation caused to the antenna matrix is small, the deformation in the thermal cycle process is in a normal range from the aspect of experimental data, and the deformation value in the working mode can allow the product to work at various environmental temperatures. The main indicator of the overall reliable operation of the antenna is the heating time for the product to reach 5-70 ℃. The initial setup installation of the antenna takes at most 30 minutes. This is the maximum allowed time for removal of atmospheric formations from the working surface of the product and entry of the product into the working mode. Experiments prove that the time required for reaching the temperature of the working temperature mode (more than 5 ℃) is as follows: the initial temperature is only 15 minutes at-50 ℃, 7 minutes at-30 ℃ and 5 minutes at-10 ℃. Therefore, the plane resistance heater can be used for outdoor large-diameter parabolic antennas, the large-diameter parabolic antennas can be heated in cold weather, particularly, the plane resistance heater can be used for defrosting by heating under the condition that the plane resistance heater is frozen or frosted due to atmospheric precipitation, and the working efficiency of the large-diameter parabolic antennas is improved.

Drawings

Fig. 1 is a cross-sectional view of a planar resistive heater.

Fig. 2 is a front view of a parabolic antenna sector with a planar resistive heater.

Fig. 3 is a cross-sectional view of the B-B plane of fig. 2.

Fig. 4 is a schematic diagram of measuring the temperature and deformation of an antenna segment, with black dots representing the sensor locations for measuring temperature and deformation.

Fig. 5 is a schematic view showing an arrangement position of the first alumina adhesive layer and the second alumina adhesive layer.

Fig. 6 is a graph of operating surface temperature versus operating time for a planar resistive heater for an antenna segment at various initial temperatures.

Wherein, 1 is first layer aluminium oxide adhesive linkage, 2 is second layer aluminium oxide adhesive linkage, 3 is first insulating layer, 4 is the second insulating layer, 5 is resistance heating element layer, 6 is the third insulating layer, 7 is the fourth insulating layer, 8 is the insulating layer, 9 is the epoxy protective layer, 10 is the antenna base member, 11 is the strengthening rib.

Detailed Description

The technical scheme of the present invention will be further described with reference to the following specific examples, but the scope of the present invention is not limited thereto.

Example 1

The cross-sectional view of the planar resistive heater is shown in FIG. 1, which is a cross-sectional view taken along the A-A plane in FIG. 2.

In fig. 2 there is shown a sector of a parabolic antenna with a planar resistive heater thereon. Fig. 3 is a cross-sectional view of the plane B-B of fig. 2 showing the reinforcing ribs 11 of the antenna segments fixedly attached to the antenna base 10.

As shown in fig. 1 to 3, the present invention provides a planar resistive heater, and a parabolic antenna (fig. 2) including the planar resistive heater. The planar resistance heater is in the form of a multilayer coating and covers part of the back surface of the antenna substrate 10, and sequentially comprises an aluminum oxide bonding layer, a first epoxy resin insulating layer, a resistance heating element layer, a second epoxy resin insulating layer, a heat insulating layer 8 and an epoxy resin protective layer 9 from the bottom layer to the outer layer.

The antenna base material 10 is a parabolic antenna sector.

Further, the multilayer coating may be provided in a strip shape extending continuously on the back surface of the antenna base 10, and may be distributed on the back surface of the antenna base in various shapes, and preferably in a U shape, or may be in a W shape, a Z shape, or the like.

The aluminum oxide bonding layer sequentially comprises a first aluminum oxide bonding layer 1 and a second aluminum oxide bonding layer 2 from the bottom layer to the outside, and is obtained by energy-accumulating explosion spraying of aluminum oxide. The first alumina bonding layer 1 has a porosity of less than 0.5% and the second alumina bonding layer 2 has a porosity of 7-20%.

When the antenna substrate is an aluminum-based material, alumina powder particles are preferentially selected as the spraying material. The first alumina bond layer 1 has high electrical breakdown strength and bond strength due to the crystalline compatibility between the aluminum base and the material of the deposited layer. The first alumina bond layer provides a range of performance characteristics: high adhesion strength (120 MPa) and thermal conductivity.

Further, the first alumina adhesive layer 1 is prepared by spraying alumina (Al ₂O₃) powder with a particle size of 5-15 μm onto the back surface of the parabolic antenna base material by energy-accumulating explosion, and has a thickness of 100-150 μm.

The second aluminum oxide bonding layer 2 is prepared by spraying aluminum oxide powder with the particle size of 60-150 mu m on the surface of the first bonding layer 1 through energy-gathering explosion, and the thickness is 200-250 mu m.

The thickness of the first alumina adhesive layer 1 less than 100 μm reduces the integrity of the coating, and the sprayed thickness exceeding 150 μm reduces the adhesive strength of the first alumina adhesive layer. After the first alumina adhesive layer 1 is formed, a second alumina adhesive layer 2 is applied on top of the first alumina adhesive layer 1 according to the roughness parameters and the number of pores specified in the material. When the coating thickness of the second alumina adhesive layer is less than 200 μm, the adhesive strength of the next third insulating layer 3 is lowered due to the reduction of the mechanical components thereof. Increasing the thickness of the second alumina bond layer to above 250 μm increases residual stress, which reduces the adhesion strength to the first alumina bond layer 1 and may also deform the antenna substrate 10. The powder particle size of the sprayed first alumina adhesive layer is 5-15 μm. Spraying particles smaller than 5 μm reduces the efficiency of the process due to the ablative effect, and particles larger than 15 μm drastically reduce the adhesion strength of the first alumina bond layer to the antenna sector 10 substrate. The alumina powder sprayed with the second alumina adhesive layer uses particles having a particle diameter of 60 to 150 μm. Spraying with particles smaller than 60 μm can reduce the number of voids and reduce the roughness of the layer 2 material, but this will reduce the adhesive strength of the next third insulating layer 3. Particles with a spray size greater than 150 μm may reduce the adhesive strength of the second alumina bond layer and destroy its integrity.

The bonding strength of the first aluminum oxide bonding layer is up to more than 120 MPa. The second alumina adhesive layer has an adhesive strength of 100MPa or more.

When the energy-accumulating explosive spraying acts on the surface of the antenna base material, a phase change occurs on the surface of the antenna base 10 when the first aluminum oxide adhesive layer and the second aluminum oxide adhesive layer are sprayed. The resulting residual stress can disrupt the flatness of the surface of the antenna sector substrate 10. In order to reduce the residual stress of the product, the first and second alumina adhesive layers are prepared by spraying not on the whole surface of the fan-shaped sheet, but as shown in fig. 5, the alumina adhesive layer comprises more than one plurality of strips which are arranged at the bottom layer position of the multi-layer coating layer in a dispersing and spacing way.

The strips can be of various shapes, preferably rectangular, and are uniformly distributed at the bottom layer position of the multilayer coating and distributed at intervals.

Further, the spacing distance between the strips is t-1.5 t.

In addition, as shown in fig. 2 and 3, the structural rigidity of the antenna base material 10 may be provided by the reinforcing ribs 11.

The first epoxy resin insulating layer, the resistance heating element layer, the second epoxy resin insulating layer, the heat insulation layer and the epoxy resin protective layer are arranged above the aluminum oxide bonding layer and cover the aluminum oxide bonding layer to form a strip-shaped multilayer coating with continuous extension.

The first epoxy resin insulating layer sequentially comprises a first insulating layer 3 and a second insulating layer 4 from the bottom surface to the outside, the second epoxy resin insulating layer sequentially comprises a third insulating layer 6 and a fourth insulating layer 7 from the bottom surface to the outside, and the first insulating layer 3 and the fourth insulating layer 7 comprise an epoxy resin adhesive A and an inorganic filler A; the second insulating layer 4 and the third insulating layer 6 comprise an epoxy resin adhesive B, an inorganic filler B and reinforcing fibers;

the thickness of the first insulating layer 3 and the fourth insulating layer 7 is 0.1-0.2mm.

The thickness of the second insulating layer 4 and the third insulating layer 6 is 0.2-0.3 mm.

The epoxy resin adhesive A or B has better electrical insulation performance.

Preferably, the epoxy resin matrix may be CYD128, SYD128, ED-20, etc.

In the embodiment, the epoxy resin adhesive is an epoxy resin matrix ED-20 (CYD 128) and a curing agent polyethylene polyamine (PEPA), and the epoxy resin adhesive is added according to the mass ratio of 100:10. The incorporation of less than 10 parts by weight of the curing agent may reduce physical and mechanical properties of the material, and the adhesive strength of the first insulating layer 3, the second insulating layer 4, the resistance heating element layer 5, the third insulating layer 6, the fourth insulating layer 7, and the epoxy resin protective layer 9. The incorporation of more than 10 parts by weight of polyethylene polyamine (PEPA) will greatly reduce the electrical properties of the layer. First, the magnitude of the electrical breakdown strength. To ensure uniform distribution of the curing agent in the binder, a hydrodynamic combination of the components is used. ED-20 and PEPA will act as binders for further filling of the composite material and subsequently form a first insulating layer 3, a second insulating layer 4, a resistive heating element layer 5, a third insulating layer 6, a fourth insulating layer 7, an epoxy protective layer 9.

When the alumina having a particle diameter of 10 to 20 μm in the inorganic filler a is less than 10 parts by weight, the technical characteristics and the electrical strength of the first insulating layer, the fourth insulating layer themselves are lowered due to deposition (sedimentation of filler particles occurs). When the alumina having a particle diameter of 10 to 20 μm in the inorganic filler A is more than 20 parts by weight, electric insulation properties of the first insulating layer and the fourth insulating layer are deteriorated due to occurrence of voids during formation of the material. The particle diameter of 10 to 20 μm is set as an optimum feature in electrical strength and manufacturability when the first insulating layer and the fourth insulating layer are applied and formed. When alumina having a particle diameter of 100nm is introduced in an amount of less than 0.5 parts by weight, the electrical insulation material of the first insulating layer and the fourth insulating layer is reduced due to the reduction in the length of the breakdown tunnel, and the thermal conductivity is also reduced, which in turn reduces the efficiency of the heating element. When the content of alumina having a particle diameter of 100nm in the composition is increased to more than 1.0 parts by weight, the electric breakdown value is lowered due to incomplete wetting of the surface of the dispersed additive solid. In this case, the length of the breakdown tunnel is reduced, resulting in a decrease in the electrical strength of the first insulating layer, the fourth insulating layer.

In a preferred embodiment, the second and third insulating layers comprise 100 parts by mass of an epoxy resin matrix, 10 parts by mass of an aliphatic polyamine curing agent, 30 to 35 parts by mass of chromium oxide having a particle size of 5 to 10 μm, and 0.2mm thick lipid-free basalt fiber impregnated in the mixture of the epoxy resin adhesive B and the chromium oxide.

The concentration and particle size of the specified filler are first selected according to the maximum value of the breakdown voltage. On the curve of the filler concentration versus the breakdown value (30-35 parts by weight per 100 parts by weight of epoxy resin matrix), the maximum is reached at a particle size of 5-10. Mu.m. When less than 30 parts by weight of chromium oxide is added to the binder, a decrease in electrical strength and thermal conductivity is observed; when it exceeds 35 parts by weight, the process characteristics during the formation of the coating layer and the electrical strength are degraded. For a filler of the same thermal conductivity, the maximum breakdown strength is uniform.

The thickness of the reinforcing fibers is preferably 0.2 to 0.3mm.

The resistance heating element layer 5 comprises an epoxy resin adhesive C, an inorganic filler C and a resistance heating element, wherein the resistance heating element is soaked in the mixture of the epoxy resin adhesive C and the inorganic filler C.

In the embodiment, the epoxy resin adhesive is an epoxy resin matrix ED-20 (CYD 128) and a curing agent polyethylene polyamine (PEPA), and the epoxy resin adhesive is added according to the mass ratio of 100:10.

Preferably, the inorganic filler C is alumina.

For alumina having a particle diameter of 10 to 20 μm in the inorganic filler C, when the component content thereof is less than 10 parts by weight, the technical properties are lowered and the electric strength is lowered due to deposition. When the content of alumina having a particle diameter of 10 to 20 μm is more than 20 parts by weight, the electrical insulation property of the resistance heating element layer 5 is deteriorated due to voids occurring in the material during formation. During the deposition and formation of the resistive heating element layer 5, a particle size of 10 to 20 μm is taken as the optimum size for the electrical strength and manufacturability. When the content of alumina having a particle diameter of 100nm is less than 0.5 parts by weight, the electrical insulating property of the material of the resistance heating element layer 5 is lowered due to the reduced length of the breakdown tunnel, which in turn reduces the efficiency of the resistance heating element. When the content of alumina having a particle diameter of 100nm in the inorganic filler C is increased to more than 1 part by weight, the electric breakdown value of the material is lowered due to incomplete wetting of the surface of the dispersed additive solid. In which case voids are formed and the electrical insulation properties of the layer are greatly reduced.

The resistance heating element is carbon fiber.

The carbon fibers are strip-shaped and distributed on the back surface of the antenna substrate in various shapes, and the preferable shapes are U-shaped (shown in fig. 2), W-shaped, Z-shaped and the like. The antenna substrate can be heated more uniformly.

The two ends of the carbon fiber are plated with copper, can be connected with an external power supply, and can be connected with the power supply in a welding mode, such as a soft soldering mode.

The resistance of the resistive heating element is preferably 30-60 ohms.

The heat insulating layer 8 is foamed polymer, and can guide heat flow, insulate heat and improve the efficacy of the electric heater. The insulating layer may reduce the heating time of the working surface, thereby eliminating atmospheric precipitation (including rain, snow, ice, etc.) from the antenna working surface.

The thickness of the heat insulating layer 8 is preferably 4 to 6mm.

The epoxy resin protective layer 9 comprises an epoxy resin adhesive D and an inorganic filler D. The epoxy resin protective layer can protect the plane resistance heater, prevent the plane resistance heater from being influenced by ultraviolet radiation, air, rain, snow and fog and the like in the open air environment, maintain the stability of the performance of the heater and prolong the service life.

The thickness of the epoxy resin protective layer 9 is generally 0.1 to 0.2mm.

Preferably, the inorganic filler D is alumina.

When the amount of the alumina in the epoxy resin protective layer is less than 15 parts by weight, protection from ultraviolet radiation is not provided, and when more than 20 parts by weight of the alumina per 100 parts by weight of the epoxy resin matrix is added, technical characteristics thereof are lowered, for example, pneumatic methods may be difficult when spraying. This will result in the integrity of the 9 th layer coating being compromised and reduce the overall functionality of the antenna thermal control system.

The preparation method of the planar resistance heater of the embodiment comprises the following steps:

Spraying a plurality of strips with dispersing intervals on the back of the parabolic antenna base material by adopting alumina powder with the grain diameter of 5-15 mu m and utilizing a cumulative explosion spraying method at the strip-shaped position of a preset multilayer coating, wherein the thickness of each strip reaches 100-150 mu m, and a first alumina bonding layer with the porosity of less than 0.5% is prepared; the bonding strength is 120MPa.

Adopting alumina powder with the particle diameter of 60-150 mu m on the surface of the first alumina bonding layer, and spraying the powder to the thickness of 200-250 mu m by utilizing energy-accumulating explosion to prepare a second alumina bonding layer with the porosity of 7-20%; the bonding strength was 100MPa.

The barrel of the explosion gun is filled with combustible mixed gas and is isolated from the main gas pipeline. Powder particles doped in a conveying gas are fed into the barrel, the mixture is ignited with a spark plug, and combustion of the mixture takes place in a detonation mode. The energy-collecting explosion spraying uses a combustible mixed gas of propane, oxygen and air, uses a multi-chamber explosion device, wherein the combustible mixed gas is simultaneously supplied in more than two combustion chambers while detonating in a precombustor, and in a main cylindrical combustion chamber, combustion product streams form detonation waves at points where the precombustor and a side annular combustion chamber converge; simultaneously, introducing alumina powder into a cylindrical nozzle which is positioned after the last side annular combustion chamber is converged with the main cylindrical combustion chamber, and accelerating and heating the alumina powder through knocking and shock waves of combustion products emitted from the main cylindrical combustion chamber and the side annular combustion chamber in sequence;

The explosion temperature of the energy-gathering explosion spraying is 3000 ℃, and the speed of the explosion wave can reach 1600-1800 m/s. The melting point of the alumina was 2072 ℃. The dispersed particles for spraying are heated to a plastic or liquid state due to interaction with the high Wen Bao bombard product. When the solid state is reached and in contact with the antenna substrate, a contact patch is formed. And then cyclically reciprocating. To ensure the geometrical parameters of the coating, the movement of the part where the sprayed coating is located is set or the spray gun is moved so as to form a coating of a given geometrical size.

further, the width of the strip is t/2 to t, the length is preferably t, and t is the width of the multilayer coating. In this example, the width t of the multilayer coating is 100mm.

Further, the spacing distance between the strips is t-1.5 t.

(2) Spraying a mixture of an epoxy resin adhesive A and an inorganic filler A on the surface of an aluminum oxide bonding layer according to the shape of a multilayer coating on the back surface of a parabolic antenna base material, and pressing and curing for 24 hours by adopting a mould of a flexible diaphragm to prepare a first insulating layer with the thickness of 0.1-0.2 mm;

The mixture of the epoxy resin adhesive A and the inorganic filler A comprises 100 parts by mass of epoxy resin matrix, 10 parts by mass of aliphatic polyamine curing agent, 10-20 parts by mass of alumina with the particle size of 10-20 mu m and 0.5-1.0 part by mass of alumina with the particle size of 100 nm;

After the first insulating layer was formed using a mold with a flexible membrane, its integrity and thickness were checked for 24 hours. If necessary, the process of forming the first insulating layer is repeated so that the thickness thereof is in the range of 0.1 to 0.2 mm. And then control its integrity and thickness.

(3) Spraying a mixture of an epoxy resin adhesive B and an inorganic filler B on the surface of the first insulating layer, then placing reinforcing fibers in the uncured mixture to infiltrate the reinforcing fibers, and adopting a mold of a flexible diaphragm to press and cure the reinforcing fibers for 24 hours to prepare a second insulating layer with the thickness of 0.2-0.3 mm;

The mixture of the epoxy resin adhesive B and the inorganic filler B comprises 100 parts by mass of epoxy resin matrix, 10 parts by mass of aliphatic polyamine curing agent and 30-35 parts by mass of chromium oxide with the particle size of 5-10 mu m.

The reinforcing fibers are infiltrated in the uncured mixture, are required to be fully infiltrated, and if the uncured mixture exists in the place where the uncured mixture is not infiltrated, the uncured mixture can be continuously coated and fully infiltrated, kept for 5 to 7 minutes, and then pressed and cured by a die.

The thickness need not be controlled because the total thickness of the layer is adjusted by the thickness of the basalt fibers, the thickness of the layer being between 0.2 and 0.3 mm. This thickness is sufficient from the point of view of the electrical reliability of the open air antenna.

(4) Spraying a mixture of an epoxy resin adhesive C and an inorganic filler C on the surface of the second insulating layer, then placing the resistance heating element in the uncured mixture to infiltrate the resistance heating element, and adopting a die of a flexible diaphragm to press and cure the resistance heating element for 24 hours to prepare a resistance heating element layer;

the mixture of the epoxy resin adhesive C and the inorganic filler C comprises 100 parts by mass of epoxy resin matrix, 10 parts by mass of aliphatic polyamine curing agent, 10-20 parts by mass of alumina with the particle size of 10-20 mu m and 0.5-1.0 part by mass of alumina with the particle size of 100 nm.

The resistance heating element is a long carbon fiber, the resistance is 30-60 ohms, and the thickness is 0.111mm;

The carbon fiber tape used for the heating element is cut off in a manner that does not damage the longitudinal threads. The lubricating oil of the strip is completely removed by means of the gas burner. The tape is plated with copper at both ends by electrolytic plating, a layer of solder is applied over the copper and the conductor is connected to a power source. In view of the characteristics of the power supply, the required power is calculated by looking at the resistance of the resistive element. Typically the resistance of the component is in the range of 30-60 ohms.

The resistive heating element is placed in the uncured mixture to allow it to infiltrate, requiring complete infiltration, and if present in the uncured area, the uncured mixture can be applied and held for 5-7 minutes, compressed using a flexible membrane for up to 24 hours, at which time the resistive heating element layer is completed.

(6) And (3) preparing a fourth insulating layer on the surface of the third insulating layer according to the method of the step (2).

(7) Coating foaming polymer on the surface of the fourth insulating layer to prepare a heat insulating layer with the thickness of 4-6 mm; in order to operate a planar resistive heater more efficiently, the heat flow should be directed at the working surface of the product. The provision of the insulating layer will reduce the heating time of the working surface and thereby eliminate atmospheric precipitation (including rain, snow, ice etc.) from the antenna working surface.

(8) And (3) coating a mixture of an epoxy resin adhesive D and an inorganic filler D on the surface of the heat insulation layer, and pressing and curing for 24 hours by adopting a mould of a flexible diaphragm to prepare the epoxy resin protective layer with the thickness of 0.1-0.2 mm.

The epoxy resin adhesive D and the inorganic filler D are 100 parts by mass of epoxy resin matrix, 10 parts by mass of aliphatic polyamine curing agent and 15-20 parts by mass of alumina with the particle size of 10-20 mu m.

Experiments prove that the bonding strength of the epoxy resin composite material depends on the magnitude of residual stress. To reduce residual stress and thereby increase bond strength, all 3-7,9 layers containing epoxy adhesives are formed separately until they are fully cured, completing the structural transformation. In practice this time is 24 hours.

In steps (2) to (6), during the formation of the epoxy composite layer, a selective accumulation process of the low molecular components of the binder occurs at the surface of the layer. During the curing of the epoxy resin, water is released in an atomic form and can accumulate on the surface of the layer. The above factors may reduce the adhesive strength between the first insulating layer, the second insulating layer, the resistance heating element layer, the third insulating layer, and the fourth insulating layer. To eliminate the above adverse effect on the adhesive strength, it is optional to form the subsequent layer in the case where the structural conversion has not been completed. The time taken for each layer is set as: in the range of 1-1.5 hours (temperature 20-22 ℃) from the completion time of the last layer. Thus, all 3 to 7 layers can be prepared using a mold with a flexible membrane, the next layer applied before the incomplete curing, and then in the final step (6), the complete curing is completed for 24 hours.

The temperature and deformation of the obtained antenna segment with planar resistive heater are detected, and fig. 4 is a graph showing the temperature and deformation measurement of the antenna segment, wherein the black dots indicate the positions of the sensors for measuring the temperature and deformation therebetween.

When the antenna is erected and then begins to work, the working surface of the antenna is frosted, piled up snow and frozen, and the antenna must be removed from the area before being used. To do this, the invention is implemented by a planar resistive heater.

The effectiveness of the prepared parabolic antenna planar resistance heater was tested by testing the function of the developed antenna thermal control system. A temperature sensor and a strain measurement system are mounted on the sector antenna base 10 (fig. 4). At the black spot of the fan-shaped piece of the heating antenna, the temperature and the maximum possible thermal deformation are detected. From the results of the study, it was found that the deformation during thermal cycling was within the normal range, and that the deformation values in the working mode allowed the product to work at various ambient temperatures. Fig. 6 shows a graph of operating surface temperature versus operating time for a planar resistive heater for an antenna segment at various initial temperatures. Temperature versus operating time of a flat resistive heater. From this schedule, the time when the antenna enters the heating operation mode can be determined.

The main indicator of the overall reliable operation of the antenna is the heating time for the product to reach 5-70 ℃. From the initial position, the antenna installation takes at most 30 minutes. This is the maximum allowed time for removal of atmospheric formations from the working surface of the product and entry of the product into the working mode. Experiments prove that the time required for reaching the temperature of the working temperature mode (more than 5 ℃) is as follows: from-50 to 15 minutes, -30 to 7 minutes, -10 to 5 minutes. The thickness of the atmospheric precipitation (including rain, snow, ice, etc.) is not critical during preparation of the operating mode. At the beginning of heating, when the temperature of the antenna surface reaches a positive temperature, the snow or ice drops from its surface, at which point the product is ready for use.

Thus, the proposed planar resistive heater method allows to increase the working efficiency of large diameter parabolic antennas in case of icing possibly due to atmospheric precipitation when operating below zero.

Claims

1. The planar resistance heater is characterized by being in a multi-layer coating mode and covering part of the back surface of an antenna substrate, and sequentially comprising an aluminum oxide bonding layer, a first epoxy resin insulating layer, a resistance heating element layer, a second epoxy resin insulating layer, a heat insulation layer and an epoxy resin protective layer from the bottom layer to the outer layer;

the multilayer coating is in a strip shape with continuous extension;

The aluminum oxide bonding layer sequentially comprises a first aluminum oxide bonding layer and a second aluminum oxide bonding layer from the bottom layer to the outside, and is obtained by spraying aluminum oxide powder through energy-gathering explosion; the thickness of the first aluminum oxide bonding layer is 100-150 mu m, the porosity is less than 0.5%, the thickness of the second aluminum oxide bonding layer is 200-250 mu m, and the porosity is 7-20%;

2. The planar resistive heater as recited in claim 1 wherein said first alumina bond layer is made by applying alumina powder having a particle size of 5-15 μm to the back of the antenna substrate by focused explosion spraying;

The second aluminum oxide bonding layer is prepared by spraying aluminum oxide powder with the particle size of 60-150 mu m on the surface of the first bonding layer through energy-gathering explosion.

3. The planar resistive heater as recited in claim 1 wherein said alumina bond layer comprises more than one plurality of strips, said strips being spaced apart on the back surface of the antenna substrate at a bottom location of the multilayer coating;

The width of the strip is t/2-t, the length of the strip is t, and t is the width of the multilayer coating;

the interval distance between the strips is t-1.5 t.

4. The planar resistive heater as recited in claim 1 wherein said first insulating layer, fourth insulating layer have a thickness of 0.1-0.2mm; the thickness of the second insulating layer and the third insulating layer is 0.2-0.3 mm;

The breakdown voltage of the coating layer of each millimeter of thickness of the first insulating layer and the fourth insulating layer reaches 80-120kV; the breakdown voltage of the coating layer of each millimeter of thickness of the second insulating layer and the third insulating layer reaches 20-60kV;

The epoxy resin adhesive A or B comprises an epoxy resin matrix and a curing agent;

5. The planar resistive heater as recited in claim 4 wherein said first insulating layer, fourth insulating layer comprises 100 parts by mass of epoxy resin matrix, 10 parts by mass of aliphatic polyamine curing agent, 10-20 parts by mass of alumina having a particle size of 10-20 μm, 0.5-1.0 parts by mass of alumina having a particle size of 100 nm;

the second insulating layer and the third insulating layer comprise 100 parts by mass of epoxy resin matrix, 10 parts by mass of aliphatic polyamine curing agent, 30-35 parts by mass of chromic oxide with the particle size of 5-10 mu m and basalt fiber with the thickness of 0.2-0.3 mm, which is soaked in the mixture of the epoxy resin adhesive B and the chromic oxide.

6. The planar resistive heater as recited in claim 1 wherein said resistive heating element layer has a thickness of 0.1 to 0.2mm; the resistance heating element layer comprises 100 parts by mass of an epoxy resin matrix, 10 parts by mass of an aliphatic polyamine curing agent, 10-20 parts by mass of alumina with the particle size of 10-20 mu m, 0.5-1.0 parts by mass of alumina with the particle size of 100nm, and a resistance heating element immersed in the mixture;

The resistance heating element is carbon fiber; copper plating can be carried out at two ends of the carbon fiber, an external power supply can be connected, and the resistance of the resistance heating element is 30-60 ohms; the thickness of the resistance heating element is 0.1-0.2 mm, and the width is 90-130 mm.

7. The planar resistive heater as recited in claim 1 wherein said insulating layer is a foamed polymer, said insulating layer having a thickness of 4-6 mm;

The epoxy resin protective layer comprises an epoxy resin adhesive D and an inorganic filler D, and the thickness is 0.1-0.2 mm.

8. The planar resistive heater as recited in claim 7 wherein said epoxy adhesive D, inorganic filler D is 100 parts by mass of epoxy resin matrix, 10 parts by mass of aliphatic polyamine curing agent, 15-20 parts by mass of alumina having a particle size of 10-20 μm.

9. A method of manufacturing a planar resistive heater as claimed in any one of claims 1 to 8, wherein said method comprises the steps of:

The method comprises the steps of (1) spraying a plurality of strips at intervals on the back of an antenna base material by using alumina powder with the particle diameter of 5-15 mu m by using a cumulative explosion spraying method, wherein the thickness of each strip reaches 100-150 mu m, and preparing a first alumina adhesive layer with the porosity of less than 0.5%;

The explosion temperature of the energy-gathering explosion spraying is 3000 ℃, and the speed of the explosion wave is 1600-1800 m/s;

(8) And (3) coating a mixture of an epoxy resin adhesive D and an inorganic filler D on the surface of the heat insulation layer, and pressing and curing by using a die to obtain the epoxy resin protective layer with the thickness of 0.1-0.2 mm.

10. A parabolic antenna comprising a planar resistive heater, characterized in that the parabolic antenna is used as a substrate, and the rear surface portion is covered with the planar resistive heater as set forth in any one of claims 1 to 8.