SU1421984A2 - Method of measuring thickness of layer of ferromagnetic material - Google Patents

Abstract

The invention relates to cont. measuring technique and is designed to measure the thickness of a layer of ferromagnetic material (C), for example, the thickness of a ferromagnetic coating of magnetic recording media during their manufacture. The expansion of the field of application of the method is achieved by the fact that the SFM is magnetized sequentially in time in two directions. Normally and tangentially to its surface, the residual magnetic flux is measured through a given SFM surface area in one case, and in the other the residual magnetic fluxes passing through two parallel platforms of the same geometrical dimensions located on both sides of the plane of the end portion of the layer are measured in such a way that the sites intersect with the plane of the end of the layer, while the thickness is determined by the measured values of the specified T07COV and the dimensions of the sites along the line of their intersection with the plane of the end of the SFM. 1 hp f-ly, 1 pc. (L

Description

14)

The invention relates to instrumentation engineering, is intended to measure the thickness of a layer of ferromagnetic material, for example, the thickness of a ferromagnetic coating of magnetic recording media during their manufacture, and is an improvement to the invention according to the author. No. 1374038.

The purpose of the invention is the expansion of the field of application due to the possibility of measuring the thickness of the layer applied to the base of a non-planar configuration as well ..

The drawing shows a device for carrying out the method.

The device consists of two magnetic systems for creating orthogonal magnetizing fields, made in the form of coaxial coils 1,2, and 3.4 fields, respectively connected via switch 5, controlled by software block 6, to the current source 7, primary converters 8-10 magnetic flux, whose magnetic axes coincide with the longitudinal axes of coils 1.2 and 3.4, respectively. The output of the primary converter 8 is connected to the input of the measuring converter 11, and the outputs of the primary converters 9. and 10 - to the inputs of the adder 12, the output of which is connected to the input of the measuring converter 13. The outputs of the measuring converters 11 and 13 are connected to the inputs of the memory 14 and 15 respectively. The control inputs of the storage units 14 and 15 are connected to the software block 6, and their outputs to the signal inputs of the voltage ratio converter 16; The control input of which is connected to the program 6, and its output to the input of the measuring device 17,

Before measuring the thickness of the ferromagnetic layer 18 deposited on the nonmagnetic base 19, the product is positioned in such a way that the magnetization axis of the OJDIHOU magnetic system is oriented normally to the surface of the layer 18 near its front portion, and the longitudinal axis of the second magnetic system is oriented tangently in relation to the surface of the layer 18, as shown in the drawing.

As a controlled sample, in particular, is considered the fer

5 0 5

Q

five

The magnetic layer 18 is of a non-planar configuration, for example an arcuate shape

The magnetization of the layer 18 of the ferromagnetic material at the initial moment of time is conducted normally to its surface, i.e. the magnetic field is directed perpendicularly to the surface of the layer 18.

Then remove the external magnetizing field. In this case, the residual magnetic flux through the elementary area on the surface of the layer, for example, of rectangular shape with area S, will be equal to

F

Tsn

k ,, k, -B.-b-l,

(one)

where k is the proportionality coefficient that accounts for the shape of the sample, i.e. the coefficient is demagneti an; Vd is the residual induction of the ferromanite material ;, b is the width of the elementary region; 1 - the length of the elementary area. At the second moment of time, the ferromagnetic layer is magnetized tangentially to its surface, i.e. the magnetic field is directed perpendicularly to the end of layer 18. Then the magnetizing field is turned off and the residual magnetic flux Φ (r, passing through a predetermined length at the end of the controlled ferromagnetic layer 18, i.e., the area located in a plane parallel to the surface of its face section, the determination of the residual magnetic flux Φzg is carried out by measuring the flux Φ and Φ through two equal-sized parallel platforms located on different sides of the test layer so that the planes intersect with the plane, the end of layer 18.

In this case, the elementary magnetic flux passing through the area of a given length at the end of the layer will be equal to the sum of the elementary flows penetrating the specified areas, i.e.

, k, BvSg, (2) where 4-g and i are magnetic fluxes,

penetrating areas.

In expression (2) it is reflected that practically the sum of the fluxes is Fgt and will always be equal to the elementary flux Fjt passing through the area of a given length at the end of the layer of ferromagnetic material, regardless of

changes in the angle of inclination of the plane of the end section, as well as to the configuration of the layer under control relative to the plane of the sites.

The thickness of the ferromagnetic material layer 18 is determined by the flux values of the fluxes and from the ratio

d s. ,

F -1

kn

1 where k is the demagnetization coefficient of a given shape of this material at a given point of the limiting hysteresis loop. The device operates in four | tact. In the first cycle, through the switch 5, controlled by the software block 6, coils 1 and 2 are initially connected to the source 7 of the current. Here, due to the magnetic field created by the coils 1 and 2, the controlled layer 18 is magnetized normally with respect to its surface. For the time of the second cycle, the switch 5, controlled by the software block 6, disconnects the coils 1 and 2 fields from the current source 7 and then measures the residual magnetic flux (1) across the sample surface with the magnetic flux converter 8. Its output signal is fed to the input of the measuring transducer 1 1, the result of which is fixed by the storage unit 14, to the control input of which from the program unit 6 a signal is received to fix the measurement result. Using the storage unit 14, information is supplied to one of the inputs of the voltage ratio converter 16. In the third cycle, through the switch 5, controlled by the software unit 6, coils 3 and 4 of the field are initially connected to the current source 7. In this case, due to the magnetic field created by the coils 3 and 4 of the floor, the controlled layer 18 is magnetized tangentially with respect to its surface. During the fourth cycle, the coils 3 and 4 fields from the current source 7 are disconnected by the switch 5 and then the residual magnetic flux (2) passing through the end surface element: ferromagnets is measured.

four

sample layer 18 controlled sample, converters 9 and 10 magnetic flux. Their output signals are fed to the inputs of the adder 12, from the output of which the resulting signal is fed to the input of the measuring converter - 13, the result of which is recorded by the storage unit

15, to the controlled input of which, from the program block 6, a signal is sent to fix the measurement result. From the output of the storage unit 15, information is fed to the second input of the voltage ratio converter 16. At the end of the fourth cycle from program block 6, the next command is issued. Outputting the result to the controlled input of the converter 16 is the relative voltage target, the output of which is fed to the input of the digital recording device 17. This signal is proportional to the measured thickness of the layer 18 of the ferromagnetic material.

The coefficient k included in the expression for determining d is determined by measuring the thickness of the reference sample. Therefore, the readings of the recorder 17 can be directly digitized in units

the thickness of the layer 18 ferromagnetic material.

Claims (2)

1. A method for measuring the thickness of a layer of ferromagnetic material according to ed. No. 1374038, characterized in that, in order to expand the area due to the possibility of measuring the thickness of a material deposited on a base of a non-planar configuration, magnetic fluxes F and F are measured through two pairs of allelic sites located on different sides of the measured layer so that their planes intersect the plane of the end face of the layer, and the magnitude of the magnetic flux Φ kt through the area of a given length Here, one at the end of the layer is determined from the ratio , 1 + F1. , -, 2. A method according to claim 1, characterized in that the sizes of the plots are chosen equal.