SU1562678A1 - Device for measuring thickness of coatings - Google Patents

Abstract

The invention relates to instrumentation engineering and can be used to control electroplating, alloys, and composite materials. The aim of the invention is to increase reliability. During operation of the device by means of a delay unit 14, a coincidence circuit 15, an interrupter 16 and a peak detector 17 controlled by a differentiating unit 5 and a signal taken from the transducer 3, false, local extrema of the current-voltage characteristics of the electrolytic polarizing element 2 are eliminated, due to the presence of impurities in the electrolyte or air bubbles when measuring coating thickness, i.e. Improved measurement accuracy is provided. 2 Il.

Description

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The invention relates to instrumentation engineering and can be used to control electroplating, alloys, and composite materials.

The aim of the invention is to increase reliability.

Figure 1 presents the block diagram of the device; figure 2 is an approximate volt-ampere curve.

The device contains a series-connected generator 1, an electrolytic polarizing element 2, a converter 3, a low-pass filter 4, a differentiating unit 5 and a zero-organ 6, a control unit 7 connected in series, a switch 8 and an indicator 9, an integrator 10 connected to the converter 3 , the storage unit 11, the input connected to the output of the converter 3, the adder 12, one of the inputs of which is connected to the output of the storage unit 11, and the output to the input of the switch 8, and the source 13 of the compensating voltage are connected connected to the second input of the adder 12, series-connected delay unit 14, the input of which is connected to the zero-or-r-6 output, and a coincidence circuit 15, the second input of which is connected to the zero-output 6, and the output connected to the block input 7, as well as a series-connected interrupter 16, the input of which is connected to the output of the integrator 10, and a second input to the output of the differentiating unit 5, and a peak detector 17, the output of which is connected to the second input of the switch 8.

The device works as follows.

The electrolytic polarizing element 2 is placed on the surface of the controlled coating (not shown) and is included in the circuit of the linearly growing voltage generator 1. Converter 3 converts the current flowing through the electrolytic polarizing element 2 into a voltage that is applied to the filter 4 and to the measurement inputs of the integrator 10 and the memory 11. The change in the magnitude of this voltage over time corresponds to the current-voltage curve, an approximate form which is presented in figure 2. Filtered from random components, the voltage from the output of the filter 4 is fed to the differentiating unit 5, which determines the value of the time derivative. A null-organ 6 is connected to the output of the differentiating unit 5, which fixes the moment of change of the sign of the derivative of the voltage at the output of the converter 3, i.e. maximum current-voltage curve. This signal goes to the interrupter 16, to the input of which the integrator 10 is connected. As a result, the output of the zero organ 6 at the time corresponding to the maximum of the current-voltage curve generates an output signal, which is recorded by the delay unit 14 and the coincidence circuit 15. If the recorded pulse exactly corresponds to the maximum of the current-voltage curve, then it causes the memory to write the value of the output voltage of the converter 3 corresponding to the maximum current (im). The output of integrator 10 is proportional to the amount of electricity (Q) flowing through the electrolytic polarizing element 2.

The output signal from the zero-organ 6 is delayed by 2 with block 14, and the coincidence circuit 15 checks for the presence of a stop signal after 2 s at the output of block 6. If after 2 s, at the moment the signal appears at the output of block 14, at the input of block 6 a signal is also present, this indicates that the process has ended. During spurious extremes, block 6 generates a signal that disappears after less than 2 sec. And at the time of the signal at the output of block 14 there is no signal at the output of block 6, since the dissolution process continues. Thus, blocks 14 and 15 analyze the extremums of false and true, but at the same time the delay line increases the error of the device, since the integrator 10 charging time is increased by the delay time. To eliminate this error, the interrupter 16, which operates from signal of the differentiating unit 5, and the storage unit 17 (peak detector 17). At the time when the extremum begins to form, the interrupter 16 shuts off the output of the integrator 10 from the input of the peak detector 17. The integrator 10 continues to charge, and the peak detector 17 stores and shows the last voltage value of the integrator 10. In the event of a false extremum

The interrupter 16, according to the signal from block 5, after some time, reconnects the output of the integrator 10 to the input of the peak detector 17, and in the case of a true extremum, this connection will no longer exist. The integrator 10 continues to charge for a delay time of 2 s, but the 1E-peak detector block 17 is disconnected, no connection is made, and it stores the actual voltage value proportional to the amount of electricity.

Claims (1)

In determining the thickness of electroplating using the proposed compensator voltage source 13. As a result, the indicator 9 is supplied with a voltage corresponding to the difference of the maximum currents per volt-ampere curve of the standard sample of the alloy-coating and the pure metal, which is proportional to the content of one of the components of the coating. After the end of the polarization process, the operator, changing the sensitivity of the indicator 9, sets the pointer to the position corresponding to the composition of the standard alloy-coating sample. Similarly, the polarization of the alloy-coating sample under study is performed. In this case, the adder 12 outputs to the input of the indicator 9 a signal corresponding to the composition of the alloy-coating sample under study. Formula invented shadows  The polarization of the standard sample of the coating with a known thickness is initially carried out. At the same time, using the control unit 7 and the switch 8, the integrator 10 remembers the voltage proportional to the amount of electricity flowed through the electrolytic polarizing element 2 at the moment of the formation of the true maximum on the current-voltage curve. The voltage from the output of the integrator 10 is supplied to the indicator 9 with an adjustable sensitivity value. After the end of the polarization process, the operator, changing the sensitivity of the indicator 9, sets the pointer to the position corresponding to the thickness of the standard coating sample. Similarly, the polarization sample of the coating is polarized. In this case, the integrator 10 outputs to the input of the indicator 9 a signal corresponding to the thickness of the test sample of the coating. When determining the composition of the electroplated coating using the proposed device, polarization of a standard sample consisting of pure metal (one of the alloy components) is initially carried out. In this case, with the help of the control unit 7 and the switch 8, the storage unit 11 memorizes a voltage value proportional to the value of the maximum current on the current-voltage curve. The voltage from the output of the storage unit 11 is supplied to the adder 12 and through the switch 8 to the indicator 9 with an adjustable sensitivity value. After the end of the polarization process, the operator sets the pointer of the indicator 9 to the zero mark by rotating the knob of the potentiometer of the source 13 of the compensating voltage. Wherein The compensating voltage source 13 produces a voltage with a polarity opposite to the polarity of the signal at the output of the storage unit 1 1 and equal in magnitude. The compensation voltage does not vary; the polarization of a standard sample of the alloy coating with a known content of one of the components is polarized. B the moment of formation of the maximum on the current-voltage curve, adder 12 sums the voltage coming from the output of the storage unit 11 and from the output of the source 13 compensating the voltage 20 five 0 five 0 five 0 five neither As a result, the indicator 9 is supplied with a voltage corresponding to the difference of the maximum currents in the current-voltage curve of a standard alloy-coating sample and a pure metal proportional to the content of one of the coating components. After the end of the polarization process, the operator, changing the sensitivity of the indicator 9, sets the pointer to the position corresponding to the composition of the standard alloy-coating sample. Similarly, the polarization of the sample of the coating alloy is carried out. In this case, the adder 12 outputs to the input of the indicator 9 a signal corresponding to the composition of the sample of the alloy of the coating. Formula invented shadows A device for measuring the thickness of a coating containing a series-connected generator, an electrolytic polarizing element, a converter, a low-pass filter, a differentiating unit and a null-organ, connected in series, a control unit, a switch and an indicator, an integrator, an input connected to the converter, a storage unit, an input connected to the output of the converter, an adder, one of the inputs of which is connected to the output of the memory. unit and the output to the input of the switch, and a source of compensating voltage connected to the second input of the adder, characterized in that, in order to increase the reliability, it is equipped with a successively connected delay unit, the input of which is connected to the output zero-org a coincidence circuit, the second input of which is connected to the output of the null organ, and the output of the It is connected to the input of the control unit, as well as a series-connected chopper, the input of which is connected to the integrator's output, and the second input is c, Voltage, V  I 1 Riga.g output of the differentiating unit, and a peak detector, the output of which is connected to the second input of the switch.