DD212104A1 - METHOD AND DEVICE FOR DETERMINING THE RHEOLOGICAL PROPERTIES OF DUNNER LAYERS - Google Patents

Abstract

The invention relates to the field of metrology and is applicable for determining the rheological properties (viscosity, Anelastizitaet) of thin layers on Festkoerperoberflaechen. The invention has for its object to develop a method and an apparatus in which the determination of the rheology is not bound to compact samples of the test medium or the complete filling of a room with the test medium. These objects are achieved by a method suitable for determining the rheological properties of thin layers on solid surfaces, together with the corresponding device according to the invention, that the solid is subjected to an ultrasonic surface wave pulse and this is detected by measuring a path again, the difference of Amplitude of the input and the output pulse as a measure of Viskositaet or Anelastizitaet the layer of an evaluation is fed.

Description

245747

Method and device for determining the rheological properties of thin layers

Field of application of the invention

The invention relates to the field of measuring technology and relates to a method and a device for determining the rheological properties (viscosity, elasticity) of thin layers on solid surfaces, for example of lubricant layers on steel wire, which is provided for cold forming by a drawing process.

Characteristic of the known technical solutions

There are already 'procedures known with which the rheology of liquids or pastes can be determined. The known methods can be attributed to three different principle solutions. This will be evaluated

1. the macroscopic flow of the test medium through narrow gaps or capillaries in stationary or moving walls or

2. the one-way or swinging movement of bodies in the test medium or

3. the damping of free, running through the test medium ultrasonic volume waves.

A major IT disadvantage of these methods is that they are not applicable to the direct examination of high tenacity thin films because they require compact samples or the complete filling of a certain sample space. The thereby realized material condition can be clearly different from that in the

-Q ΠΪ7 IG PO * Π f, y .-; rn

ZAb 7 4 7 b ²

Distinguish training as a thin layer. This is especially true for substances of the pail, the viscosity of which strongly depends on the deformation history (thixotropy).

Object of the invention

The object of the invention is to create conditions for the determination of the rheology of high tenacity thin layers on plaque body surfaces.

Explanation of the essence of the invention

The invention has for its object to develop a method and an apparatus in which the determination of the rheology is not bound to compact samples of the test medium or the complete filling of a room with the test medium. '·

This object is achieved in a method for determining the rheological properties of thin layers on solid surfaces according to the invention in that - the plague body with a ültraschall-Qberflächenwellenimpuls applied and this is measured again after passing through a distance, wherein the difference in the amplitude of the input and the output pulse is supplied as a measure of the viscosity or anelasticity of the layer of an evaluation.

For the evaluation, the amplitude of the pulse detected after one or more passes through the path is taken according to the invention. It is expedient to generate the upper wave nichine pulse by means of an electroacoustic transducer or by thermoelastic excitation.

To carry out the method, the invention includes a device in which a pulse generator is connected with one of its outputs with an ultrasonic transmitting transducer which can be coupled to a plague body and with a further output to one of the inputs of a pulse amplifier whose second input can be coupled to a plunger body Ultrasonic receiving transducer and whose output is connected to a pulse height meter or a monitor ".

Instead of the transmitting and receiving transducer and a common converter can be used, which is connected to the guided to the pulse amplifier output. The pulse height meter can be coupled according to the invention with a computer for the calculation of the rheological properties of the layer.

With the method according to the invention, the conditions are created for the first time to directly measure the rheology of thin layers. Previously, the results of the measurements on compact samples had to be transferred to the thin layer, despite the fact that considerable uncertainties had to be taken into account. In the invention, in contrast to the previously known method of rheology determination by means of ultrasound, the damping medium is not itself (or only in part) as a carrier of sound propagation, but is coupled only as a damping element to such a carrier (plague). According to the method of the invention, it is possible at a certain frequency or wavelength and thus known penetration depth of the ultrasonic surface waves to determine the proportion of attenuation by the layer via a comparative measurement on a plague body without a layer. In the case of viscous layers, the attenuation is directly proportional to the viscosity and the layer thickness, as long as the layer thickness is much smaller than the wavelength. Since the ultrasonic surface waves can follow surface curvatures whose radius is significantly greater than the wavelength, the surface of the path can also be be curved.

embodiment

The invention is explained in more detail below with reference to two exemplary embodiments. The accompanying drawing shows with the figures 1 and 2 embodiments of the device for carrying out the method.

example 1

According to Pig. 1 is a pulse source 1 connected with its one output to an ultrasonic transmitting transducer 2 and with its second output to one of the two inputs of a pulse converter

Stronger 3 connected. The ultrasonic transmitting transducer 2, like an ultrasonic receiving transducer 4 is coupled to a solid 5, on which a layer β is applied from a Pestschinierstoff whose viscosity is to be determined. The ultrasonic receiving transducer 4 is connected to the second input of the pulse amplifier 3. At the output of the pulse amplifier 3, a pulse height meter 7 is connected with a digital display, in its place, a monitor can be used.

Via the ultrasonic transmitting transducer 2, the plague body 5 is subjected to a Ültraschall surface wave pulse. The pulse passes through the .Wegstrecke to the ultrasonic receiving transducer 4, wherein its amplitude is reduced due to the damping effect of the viscous layer 6. In the pulse-height blade 7 or on the monitor, the pulse height is H ₁ and after one Hp measured "after three passes through the path 1, the damping coefficient or is then given by the relationship

<X = § ^ r. Ig ^ - (in dB / m). , From this, the viscosity -τη can be calculated according to the relationship

E .c ²

be determined, in which mean: f = ültraschallfrequenz S = modulus of elasticity of the substrate

c = transversal velocity of sound of the substrate ) = puncture of the Poisson's constant of the plague body,

The determination of the viscosity ^ from the pulse heights EL and H ₂ can be calculated separately or by means of a height-linked to the pulse meter 7 calculator «

Example 2

2, the output of a pulse source 1 with an ultrasonic transmitting and receiving transducer. 8

and a pulse amplifier 9 connected. The ultrasonic transmitting and receiving transducer 8 is coupled to the periphery of a plaque body 11 coated with a solid lubricant 10. At the output of the pulse amplifier 9, an IQnpulshöhenmesser 12 or a monitor is connected.

With this device, the viscosity of the Festschinierstoffschicht 10 is determined analogously as in Example 1, wherein the pulse height EL after a single and E ₂ after two passes through the resulting from the circumference of the plague body 11 distance 1 is measured. In this case, "the damping coefficient o <is given by the relation

OO 1

O <= ψ ± . Ig -1 (in dB / m). (III)

In both examples, the weakening of the ultrasonic signal caused by the substrate or (in Example 2) by the scattering at the measuring head is to be eliminated by self-measurements.

Claims (6)

245747 5 ° invention claim 1. A method for determining the rheoiogical properties of thin layers on Pestkörperoberflächen, characterized in that the plague body is acted upon by an ultrasonic surface wave pulse and this is measured again after passing through a distance, wherein the difference in the amplitude of the input and the output pulse as a measure the viscosity or, the anelasticity of the Schicht.einer evaluation is supplied. ' 2. Method according to item 1, characterized in that the amplitude of the pulse detected after one or more passes through the path is used for the evaluation * 3. The method according to item 1, characterized in that the surface acoustic wave pulse is generated by means of an electro-acoustic transducer or by thermoelastic excitation. 4. A device for carrying out the method according to item 1, characterized in that a pulse generator (1) is connected with one of its outputs with a ültraschall transmit transducer (2) which can be coupled to a plague body and with a further output to one of the inputs of a pulse amplifier, whose second input is connected to an ultrasonic receiving transducer ( 4 ) which can be coupled to the plague body and whose output is connected to a pulse height meter (7) or a monitor. 5. .Einrichtung according to item 4, characterized in that instead of transmitting and receiving transducer, a common transducer (S) is used and this with the pulse to the amplifier (3 ) guided output of the pulse generator (1) is connected. 6. Device according to item 4, characterized in that the pulse height meter (? -F2) is coupled to a calculator for calculating the rheological properties of the S _c For this 1? - "-! -. Hnungeri