DD219066A3 - TEST METHOD FOR DETERMINING METALLIC LAYER INTERRUPTIONS - Google Patents

Abstract

Test method for the detection of metallic layer breaks of bodies consisting of at least two metallic materials. The aim of the invention is to detect metallic outer layer interruptions and to allow the simplest and most continuous possible control of the quality of the material. Taskgemaess a defective outer layer is determined by means of electromotive force. According to the invention, the part of the body to be tested is guided through one or more electrolytic solutions into which a counter electrode is simultaneously immersed and the electrical potential between this electrode and the test piece is continuously measured and a potential change when a defect is immersed is evaluated as an indicator. The invention is applicable in the electrical industry, metalworking industry.

Description

Test Method for Detecting Metallic Layer Interruptions Field of application of the invention

The invention relates to a test method for detecting metallic layer breaks of bodies, which consist of at least two metallic materials, of which a material is arranged as an outer layer, in particular of bodies of composite material.

Characteristic of the known technical solutions,;

It is known that often metallic body with a coating of another metal, for. By electroplating, by plating, to thereby provide protection against aging or even a saving of the more valuable metal (e.g., gold, silver, platinum, copper, zinc). A typical example of this is the aluminum-copper power conductors, in which the good properties of copper (solderability, very good conductivity, corrosion resistance, contact ability) are exploited on the wire surface, whereas inside the conductor the more available, but not so high-grade aluminum is arranged becomes. , ".

For all bodies made of composite materials, an examination of the integrity of the outer layer is an absolute prerequisite for achieving the desired effect for the whole product; Outside layer interruptions, ie defects, z. B. lead to increased corrosion and also provide such. B. in aluminum-copper wire mechanical weaknesses. ', "...." .. ·' .- '. , "....

Are known test methods that make a control of the surface by scanning with a pen or with piezoelectric or electrostrictive ceramic (DE-OS 29 50 627), wherein a conversion of mechanical quantities into electrical and then these come to the display (DE-OS 138 289.1 773 611). Also known are methods of controlling the surface by irradiation with different electromagnetic radiation, such. Visible light or X-rays (DE-OS 2,100,304, 1,961,067, 1,919,879, 1,910,084). Here, the different reflection or adsorption behavior is exploited at the defects. '

Another method is based on the different conductivities that occur at the defects. In this method, the wire to be examined is moved through a coil and evaluated the occurring inductance either via a measuring bridge or by matching a resonant circuit (DE-OS 27 07 023).

These known methods are also suitable for the control of simple surfaces and show depending on the sensitivity setting all surface defects, so not only layer breaks in the top layer, but also color changes of the surface due to contamination in the optical process, reducing the layer thickness to a low level or Qüerschnittsverringerungen in the inductive method, depressions in the material without destruction of the outer layer during the scanning process.

Object of the invention

The solution according to the invention should make it possible to detect only certain imperfections, ie metallic outer layer interruptions, in which the inner metallic material is directly in communication with the environment, while ignoring other surface irregularities and, moreover, as far as possible to allow easy and continuous control of material quality.

Explanation of the essence of the invention

The invention has for its object to develop a test method in which a defective outer layer is detected by means of electromotive force.

The features of the invention are that the part of the body to be examined is passed through one or more electrolytic solution (s), in which a counter electrode is simultaneously immersed and the electrical potential between this electrode and the test piece is measured continuously. When a defect is immersed, the measured potential changes due to the different normal potentials of metals. This photocurrent change is used according to the invention for the display and evaluation of the defects on the material to be tested. Conveniently, a counter electrode made of the same material as the outer layer of the specimen is used. Upon examination of a strand-like body, it passes through mechanical contacts such as carbon brushes, metal brushes, rollers and the like prior to immersion in the bath to ensure electrical connection of the measuring device to the material to be tested. Instead of the mechanical contacts, a liquid metal bath such as mercury or an additional electrolyte bath may also be used.

embodiment

The method is particularly suitable for testing aluminum-copper composite wires. Via a roller system, the wire, which was rewound between two drums, into the electrolyte bath, consisting of a saline solution introduced. Copper is used as the counter electrode, and a second electrolyte bath is used as contact with the voltmeter. Normally, the voltage displayed is less than 0.08V; in the event of errors, voltages> 0.2 V are displayed on the connected instrument. A change in the flow rate of the specimen between 0 and 2m / s has no effect on the 'measurement result.

Claims (5)

Invention claims: 1. A test method for detecting metallic layer breaks of strand-like bodies, which consist of at least two metallic materials, of which one or the other completely surrounds the one or the other with a surface layer, in particular of composite bodies, characterized in that the part to be examined to be tested Body is guided in a known manner by an electrolytic solution, in which a counter-electrode is immersed simultaneously and the electrochemical potential between this electrode and the specimen is measured and a potential change is evaluated when dipping a defect as an indicator. , 2. Test method according to item 1, characterized in that the test piece is pulled through several solutions. 3. test method according to item 1 and 2, characterized in that when testing a strand-like body before the same immersion in the electrolyte to achieve an electrical connection of the measuring device with the material to be tested mechanical contacts, such as metal or. Carbon brushes, rollers and the like passes. 4. Test method according to item 1 and 2, characterized in that when testing a rope-shaped body the same before immersion in the electrolyte to achieve an electrical connection of the measuring device with the material to be tested, a bath of liquid metal, such as mercury passes. 5. test method according to item 1 and 2, characterized in that when testing a strand-like body, the same passes before immersion in the electrolyte to achieve an electrical connection of the measuring device with the material to be tested an additional electrolyte bath.