RU2579805C2 - Method to increase sensitivity of electromagnetic sensors of speed pulsations of hydrophysical fields converters - Google Patents

Abstract

FIELD: measurement equipment.

SUBSTANCE: invention relates to measurement equipment and is designed to measure speed of flow of electroconducting fluid, for instance, sea water. The method to increase sensitivity of electromagnetic sensors of speed pulsations of hydrophysical fields converters according to the invention includes application of platinum black at end surfaces of platinum electrodes installed in gaps of the sensor magnetic system, aflush with their outer surface, at the same time prior to application of platinum black the electric insulation material of the sensor is coated with a layer of electric insulating material, inert to hydrochloric, nitric and chloroplatinic acids, at the same time the thickness of the additional layer is chosen on the basis of possibility to provide blocking of impurities diffusion from the compound in process of electrodes platinum plating.

EFFECT: reduced electric resistance between an electrode and a water medium, and accordingly reduced electrochemical noise arising due to chemical impurities diffusing into platinum black onto electrodes, which provides for increased sensitivity of an electromagnetic sensor of speed pulsations.

6 cl, 1 dwg

Description

The invention relates to measuring technique and is intended to measure the flow rate of an electrically conductive liquid, such as sea water.

A known sensor of the flow velocity of an electrically conductive fluid of electromagnetic type (RF patent No. 2335774, publ. 10.10.2008), which is a dielectric housing placed on a metal base of non-ferromagnetic alloy with a magnetic system inside the dielectric housing with measuring electrodes, the end surfaces of which are conformal with the bypass of the dielectric housing.

There is also a method for increasing the sensitivity of a sensor by reducing the electrical resistance between the electrode and the aqueous medium and, accordingly, reducing electrochemical noise. To this end, the end surfaces of the platinum electrodes in contact with the aqueous medium, placed in the gap of the magnetic system of the sensor, are coated with platinum black. In this case, the process of platinum plating and deposition of platinum black on the end surfaces of electrodes embedded in an epoxy compound is carried out in a known manner, used to platinum individual electrodes, using electrolysis in a chemically aggressive electrolyte based on platinum chloride, using concentrated nitric and hydrochloric acids.

In contrast to the plating of individual electrodes, when plating the end surfaces of the sensor electrodes embedded in an epoxy compound, chemical impurities are released from the compound under the influence of electrolytes, which diffuse into the platinum black deposited on the electrodes, which leads to an insufficient decrease in the electrical resistance of the electrode - medium interface and not allows you to achieve the desired level of intrinsic noise of the sensor.

The technical result of the claimed invention is to reduce the electrical resistance between the electrode and the aqueous medium and, accordingly, to reduce electrochemical noise arising due to chemical impurities diffusing into the platinum black deposited on the electrodes, which increases the sensitivity of the electromagnetic pulsation sensor of the velocity transducers of hydrophysical fields.

To achieve the specified technical result when implementing the method of increasing the sensitivity of electromagnetic sensors of pulsations of the velocity transducers of hydrophysical fields, including the application of platinum black on the end surfaces of platinum electrodes installed in the gaps of the magnetic system of the sensor, flush with their outer surface, in accordance with the invention before applying platinum black, the electrical insulation material of the sensor is covered with an additional layer of electrical insulation material, deleterious to hydrochloric acid, nitric acid and chloroplatinic acids, wherein the thickness of the additional layer is selected based on the possibility of providing blocking diffusion of impurities from the compound during the platinized electrodes.

In special cases of implementation, the application of an additional layer of electrically insulating material on the dielectric surface of the sensor is carried out sequentially with the initial application of it on the entire surface of the sensor and subsequent mechanical cleaning of the end surfaces of the electrodes.

The thickness of the additional layer of electrical insulating material, mainly not less than 5 microns.

As an additional electrically insulating material, polyparasilylene or fluoroepoxy varnish can be used.

In special cases of the method, before applying an additional layer of electrical insulating material in the end surfaces of the measuring electrodes, holes can be made, mainly with a depth of 0.2-0.3 mm

The technical solution is illustrated by the following graphic materials, which do not cover and, moreover, do not limit the entire scope of the claims of this technical solution, but are particular examples of the invention.

FIG. 1 is an example of a phased implementation of the method with the implementation of the hole in the end of the sensor electrode.

The method is implemented as follows.

A layer of an additional electrically insulating coating is applied to the sensor, the outer surface of which is formed by an epoxy compound. In this case, the electrodes can be protected, for example, with silicone.

Polyparaxylylene or fluoroepoxy varnish can be used as the material of the additional electrically insulating coating, since they are not affected by hydrochloric, nitric, and platinum chloride hydrochloric acids, which are used when plating the sensor’s measuring electrodes.

Polyparaxylylene coating is carried out in stationary installations of the Xiger-1M type.

Fluorine-epoxy coating is applied in vacuum spraying chambers.

An additional layer of electrically insulating material is preferably applied with a thickness of at least 5 μm, which ensures the blocking of diffusion of impurities from the compound during plating of the electrodes.

After completion of the polymerization process of the applied additional electrically insulating coating, the end surfaces of the measuring electrodes of the sensor are plated by a known technology.

In particular cases of implementing the method, a layer of an additional electrically insulating coating is applied to the entire surface of the manufactured ripple velocity transducer of hydrophysical field transducers before plating the measuring electrodes.

After the completion of the polymerization process of the applied additional electrically insulating coating, the end surfaces of the measuring electrodes of the sensor are cleaned to metal platinum. Cleaning is carried out mechanically, for example, using a cutter or a hand tool.

After cleaning the measuring electrodes, plating of their end surfaces is carried out according to known technology.

To improve the manufacturability and quality of cleaning the end surfaces can be used processing technology, with the formation of holes (Fig. 1).

In this case, before applying an additional electrically insulating coating, holes 2 are made in the end part of the platinum measuring electrode 1, which are recesses with a depth of 0.2-0.3 mm.

The holes 2 can be performed, for example, using a cutter or a hand tool.

After processing all the platinum measuring electrodes 1 on the dielectric housing 3 of the sensor, including the end parts of the measuring electrodes 1, an additional electrically insulating coating 4 is applied, ensuring the absence of open areas of the compound of the dielectric housing 3.

The holes 2 in the end parts of the measuring electrodes 1 ensure the integrity of the additional electrically insulating coating 4 of the compound of the dielectric housing 3 of the sensor when plating the electrodes, since the end part of the platinum measuring electrode 1 is cleaned before platinizing from the additional electrically insulating coating 4 only in hole 2, without capturing the electrode boundary - compound.

In addition, wells 2 perform an additional function of preserving platinum black due to the fact that it does not undergo abrasion due to the abrasive properties of water when the sensor moves in an aqueous medium.

Thus, the implementation of the method of increasing the sensitivity of the sensor using an additional electrically insulating coating ensures the absence of chemical impurities diffusing into the platinum black deposited on the electrodes, and consequently, the electrical resistance between the electrode and the aqueous medium and, accordingly, the level of electrochemical noise of the measuring electrodes to the value corresponding to the noise of the platinum electrodes platinum-plated under ideal conditions, separate from the design, which ensures Vaeth sensitization electromagnetic velocity sensor pulsations.

The inventive method of increasing the sensitivity of electromagnetic sensors of pulsations of the velocity transducers of hydrophysical fields can be carried out by known technological methods using existing materials and equipment.

Claims (6)

1. A method of increasing the sensitivity of electromagnetic sensors of pulsations of the velocity transducers of hydrophysical fields, including applying platinum black on the end surfaces of platinum electrodes installed in the gaps of the magnetic system of the sensor, flush with their outer surface, characterized in that before applying platinum black, the insulating material of the sensor is coated with an additional layer electrically insulating material inert to hydrochloric, nitric and platinum chloride acids, with thicknesses the additional layer is selected based on the possibility of providing blocking diffusion of impurities from the compound during the platinized electrodes. 2. The method according to claim 1, characterized in that the application of an additional layer of insulating material on the dielectric surface is carried out sequentially with the initial application of it on the entire surface of the sensor and subsequent mechanical cleaning of the end surfaces of the electrodes. 3. The method according to claim 1 or 2, characterized in that the additional layer of electrical insulating material is made with a thickness of at least 5 microns. 4. The method according to claim 1 or 2, characterized in that as an additional electrically insulating material using polyparaxylene or fluoroepoxy varnish. 5. The method according to claim 2, characterized in that, before applying an additional layer of electrically insulating material, holes are made in the end surfaces of the measuring electrodes. 6. The method according to claim 5, characterized in that the wells are 0.2-0.3 mm deep.

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