CN103389263A - Testing apparatus for dynamic galvanic corrosion - Google Patents

Abstract

The invention belongs to the technical field of metal material corrosion tests, and relates to a dynamic galvanic corrosion test device. A rotating electrode sample is embedded in a rotating electrode inlay seat, and a threaded hole is formed in the center of the non-test surface of the rotating electrode sample to realize the connection with the rotating shaft. The positive electrode of the galvanic corrosion measuring instrument is connected with the rotating electrode sample through a brush; the diamond grinding column is fixed on both sides of the fixed electrode, and there are channels in the fixed electrode mosaic seat and the height-adjustable support. The copper wire is electrically connected by a spring, the negative electrode of the galvanic corrosion measuring instrument is directly connected to the fixed electrode, and the height-adjustable support and the fixed electrode mosaic seat are connected by a high-density threaded screw; the test method includes installing the test device and setting the test conditions And three steps of controlling the speed and recording data; the device structure is simple, the operation is simple, the method principle is reliable, the practicability is strong, the test conditions are easy to realize, the cost is low, the test efficiency is high, and the environment is friendly.

Description

A dynamic galvanic corrosion test device

Technical field:

The invention belongs to the technical field of metal material corrosion tests, and relates to a new galvanic corrosion test device, in particular to a dynamic galvanic corrosion test device, which realizes the galvanic corrosion test of dissimilar metal materials in a moving state.

Background technique:

At present, the corrosion problem is an important factor that affects and restricts the safe use of ships, marine engineering and coastal buildings. Ships, ship-borne equipment, coastal buildings, docks and offshore platforms are in environments with high salinity, high humidity and heavy pollution all year round. , is very prone to corrosion; among many types of corrosion, galvanic corrosion is a relatively common and important type of corrosion. From the design and manufacture of ship-borne equipment, ships and marine engineering equipment, many factors will cause serious damage. Galvanic corrosion; the so-called galvanic corrosion refers to localized corrosion at the contact of dissimilar metals in the same medium due to different corrosion potentials, also known as contact corrosion or bimetallic corrosion. In order to realize the functions of various components in ship-borne equipment, ships and ocean engineering equipment, different types of materials need to be selected. For example, in order to achieve light weight, ships and ship-borne Grinded steel parts are used as stress-bearing parts, which leads to a large number of dissimilar metal connections. If insulation or physical isolation measures fail, galvanic corrosion will inevitably occur, and welding, riveting, screwing, In the actual application of various connection methods such as bearing connection, relative motion or friction will also occur, and then dynamic galvanic corrosion will accelerate the corrosion process; in marine engineering, steel cables are directly connected with stainless steel shackles, Dynamic galvanic corrosion also occurs under the action of seawater. In order to prevent local corrosion damage caused by dynamic galvanic corrosion, it is very necessary to study the behavior and law of dynamic galvanic corrosion, and take effective control measures for its corrosion characteristics; most of the galvanic corrosion tests in the existing laboratories are based on National standard GB/T15748-1995 "Galvanic corrosion test method for marine metal materials", in this standard, the corrosion medium is static sea water, the sample area is 1:1 static suspension, the operation method is simple, easy to implement, and the test data is stable , but the disadvantage is that it cannot simulate the flowing seawater environment, nor can it simulate the mutual friction motion of dissimilar metals. In practice, the seawater erosion environment is much more serious than the static seawater corrosion, and the mutual friction between dissimilar metals will also accelerate galvanic corrosion, so The experimental data obtained from static seawater cannot truly reflect the true tendency and degree of galvanic corrosion between materials.

Most of the existing technologies are aimed at dynamic friction and wear corrosion and galvanic corrosion respectively. For dynamic friction and wear corrosion, there are generally two test methods: erosion and abrasion. The test methods for simulating seawater erosion include rotary erosion, pipe flow erosion, and jet erosion. etc. For example, the "Pipe-flow Liquid-Solid Two-phase Flow Erosion Corrosion Experimental Device" disclosed in Chinese Invention Patent No. 00253528.9 introduces a pipe-flow type erosion simulation corrosion test device, which provides a method for research or measurement under high flow rate conditions. The influence of the distribution of the local flow velocity and state of the fluid and the movement characteristics of the particles near the pipe wall on the erosion and corrosion of materials; the "jet-type liquid-solid two-phase flow erosion and corrosion experimental device" disclosed in the Chinese Invention Patent No. 200720014413. Real-time measurement of long-term electrochemical parameters under different flow rates, spray angles and medium temperatures; the "multifunctional submerged spray cavitation test device" disclosed in the Chinese invention patent No. 200810249618.6 realizes the simulation of material erosion under different pressure environments Measurement of corrosion performance, such as electrochemical measurement of materials under different cavitation intensities; Chinese invention patent No. 201010603782. The advantages of the erosion corrosion experimental device are that it can simulate the axial erosion corrosion of the inner wall of the pipeline under rotating conditions, and at the same time control the flow rate, medium composition and temperature, as well as real-time electrochemical measurement and weight loss measurement; in practice, for the test method of simulating material wear, At present, there is no recognized evaluation method for the reliability of corrosion and wear test equipment. The existing corrosion and wear test equipment at home and abroad are all designed and manufactured by researchers according to their own research purposes. There is no finalized corrosion and wear testing machine, such as The Chinese invention patent No. 201110207373.2 discloses "a high-temperature and high-pressure in-situ scratch and corrosion wear test device" mainly introduces a high-temperature and high-pressure in-situ scratch corrosion wear test device, which can realize the surface of the sample under high temperature and high pressure. In-situ single scratch and reciprocating corrosion wear research, and can detect the process of sample surface film from destruction to repassivation during the process of scratch or corrosion wear on the sample surface. In addition, there are currently many invention patents for galvanic corrosion. For example, a "multi-channel galvanic corrosion experiment data acquisition device" disclosed in the invention patent No. 200420098658.2 introduces a fully automatic multi-channel intelligent acquisition and processing The galvanic corrosion test data acquisition device of the data can measure the galvanic corrosion potential and current of multiple sets of galvanic couples in situ at the same time, the data acquisition is accurate, the efficiency is high, and a lot of manpower and financial resources are saved; the Chinese invention patent No. 200910238567.1 is disclosed "A galvanic corrosion test device" introduced a galvanic corrosion measurement device between any two different metal materials in a solution medium containing CO ₂ /H ₂ S. And the galvanic corrosion test device with different area ratio changes can also perform high temperature and high pressure galvanic corrosion immersion weight loss tests with different area ratios; none of the above patented technologies has realized the effective combination of dynamic friction and wear corrosion and galvanic corrosion. In addition, there is a Chinese invention patent No. 201010225412 which discloses "a test method for simulating galvanic corrosion in a seawater scouring environment". This invention combines galvanic corrosion and dynamic friction and wear corrosion, and can realize galvanic corrosion in a simulated seawater scouring environment However, the method introduced in this patent cannot realize the simulation of the working conditions of mutual friction and wear between metals, and in the technical field of galvanic corrosion of metal materials, there is no reference to the friction of dissimilar metal materials under the environmental conditions of flowing seawater (or other corrosive media). There are no identical or similar technical records or literature reports, so it is sought to design a simple, fast and accurate dynamic galvanic corrosion test device for dissimilar metals in flowing seawater or other corrosive medium environments. The galvanic corrosion test in the process of mutual motion or friction has good scientific research significance and practical value.

Invention content:

The purpose of the present invention is to overcome the shortcomings of the prior art, and seek to design and provide a dynamic galvanic corrosion test device, which is used for galvanic corrosion tests in the process of mutual movement or friction of dissimilar metals in flowing seawater or other corrosive medium environments.

In order to achieve the above object, the main structure of the dynamic galvanic corrosion test device involved in the present invention includes a galvanic corrosion measuring instrument, a rotor, a brush, a rotating shaft, a corrosion solution, a rotating electrode mosaic seat, a rotating electrode sample, an emery column, Fixed electrode, fixed electrode mosaic seat, corrosion solution tank, height-adjustable support, high-density threaded screw, base, rotating electrode controller and channel; it is divided into two parts: rotating electrode system and fixed electrode system, of which the rotating electrode The system consists of a rotating electrode controller, rotor, rotating shaft, brushes and rotating electrode samples. The rotating controller can realize continuous adjustment of the rotating speed from 0 to 3000 rpm, with an accuracy of ±0.01 rpm. The electrode sample is inlaid in the imported PTFE rotating electrode inlaid seat in a tight fit, so that there is no corrosive medium between the rotating electrode sample and the non-metal inlaid seat, and the inlay material is higher than the metal electrode material. Therefore, it can avoid the occurrence of crevice corrosion; there is a threaded hole in the center of the non-test surface of the rotating electrode sample to realize the threaded connection with the rotating shaft, and the screwing direction of the thread is opposite to the rotating direction of the rotating shaft; the rotating electrode sample After combining with the rotating electrode mosaic seat and the rotating shaft, test the coaxiality of the combination to make its eccentricity between 0.001-0.005, and the positive electrode of the galvanic corrosion measuring instrument is connected to the rotating electrode sample through a brush; The electrode system includes a diamond grinding column, a fixed electrode mounting seat, a fixed electrode, a corrosion solution tank, a height-adjustable support and a base; the diamond grinding column is fixed on both sides of the fixed electrode with super glue, and is higher than the fixed electrode mounting seat. The horizontal surface is 3-5mm, and the height of the two diamond grinding columns is the same to achieve friction on the rotating electrode sample; the fixed electrode mosaic seat is the same as the rotating electrode sample mosaic material, and the diameter of the fixed electrode is the diameter of the rotating electrode sample 1/2, the two electrodes are always concentric during the test; there are channels in the fixed electrode mosaic seat and the height-adjustable support, the fixed electrode and the copper wire are electrically connected by a spring, and the negative electrode of the galvanic corrosion measuring instrument is directly The fixed electrode is connected by a copper wire, and the height-adjustable support and the fixed electrode mosaic seat are connected by a high-density threaded screw. By adjusting the high-density threaded screw, the height of the fixed electrode can be adjusted to adjust the distance between the diamond grinding column and the rotating electrode. distance, control the friction depth, and the height adjustment range of the high-density threaded screw is 0-50mm, accurate to 0.1mm and can be fine-tuned.

The test method involved in the present invention specifically comprises three steps of installing test equipment, setting test conditions and controlling the rotating speed and recording data:

(1) Install the test device: After installing the rotating electrode system and the fixed electrode system according to the conventional structural relationship, adjust the height of the height-adjustable support under the fixed electrode, and raise the fixed electrode to the diamond grinding column and the rotating The position where the electrode sample is in close contact;

(2) Set the test conditions: add the corrosion solution to the corrosion solution tank, so that the corrosion solution is not over the rotating electrode sample;

(3) Control the rotation speed and record data: adjust the rotation speed of the rotating electrode sample through the rotating electrode controller, observe the change of the galvanic current at the same time, and record the data accurately.

Compared with the prior art, the present invention can simultaneously simulate flowing seawater or other corrosive media and the mutual friction motion of two metal materials, and the device comprehensively considers the influence of friction and the flow of corrosive solution on galvanic corrosion; it adopts a rotating electrode system to realize The relative flow of the corrosive solution is used to simulate the flowing corrosive solution; the fixed electrode system uses corundum to rub the rotating electrode to simulate the friction or abrasion of the electrode material; the positive and negative poles of the galvanic corrosion measuring instrument are respectively connected to the rubbed rotating electrode And fixed pair electrodes, to realize the measurement of the galvanic couple current between the friction-wear metal and the fixed pair metal in the flowing corrosion medium, while simulating the mutual motion state between the coupling materials, it is also real The relative flow of corrosive solution is simulated; the test data obtained by using this test device can truly reflect the corrosion law of materials and components under the condition of mutual (or friction) movement, and provide favorable corrosion information for the development of materials used in this condition Research means; the device has simple structure, easy operation, reliable method principle, strong practicability, easy realization of test conditions, low cost, high test efficiency and environmental friendliness.

Description of drawings:

Fig. 1 is a schematic diagram of the main structure of the device of the present invention.

Fig. 2 is the change trend diagram of the galvanic couple current with the rotating speed of titanium and stainless steel measured in the present invention under the condition of flowing seawater.

Detailed ways:

The present invention will be further described in detail below in conjunction with the accompanying drawings and examples.

Example:

The main structure of this embodiment includes a galvanic corrosion measuring instrument 1, a rotor 2, a brush 3, a rotating shaft 4, a corrosion solution 5, a rotating electrode mosaic seat 6, a rotating electrode sample 7, an emery column 8, a fixed electrode 9, Fixed electrode mosaic seat 10, corrosion solution tank 11, height-adjustable support 12, high-density threaded screw 13, base 14, rotating electrode controller 15 and channel 16; it is divided into two parts: rotating electrode system and fixed electrode system , wherein the rotating electrode system is composed of a rotating electrode controller 15, a rotor 2, a rotating shaft 4, a brush 3 and a rotating electrode sample 7, and the rotating controller 15 can continuously adjust the rotating speed from 0 to 3000 rpm with an accuracy of ±0.01 rev/min, the rubbed rotating electrode sample 7 is inlaid in the imported PTFE rotating electrode inlay seat 6 in a tight fit, so that there is no gap between the rotating electrode sample 7 and the non-metal inlay seat. The corrosive medium is deep, and the inlay material has higher elasticity than the metal electrode material, so the occurrence of crevice corrosion can be avoided; the center of the non-test surface of the rotating electrode sample 7 is provided with a threaded hole to realize the threaded connection with the rotating shaft 4. The tightening direction is opposite to the rotation direction of the rotating shaft 4; after the rotating electrode sample 7 and the rotating electrode mosaic seat 6 are combined with the rotating shaft 4, the coaxiality of the combination is tested so that the eccentricity is between 0.001-0.005, The positive electrode of the galvanic corrosion measuring instrument 1 is connected to the rotating electrode sample 7 through the brush 3; wherein the fixed electrode system includes a diamond grinding column 8, a fixed electrode mosaic seat 10, a fixed electrode 9, a corrosion solution tank 11, and a height-adjustable support Seat 12 and base 14; Emery grinding post 8 utilizes superglue to be fixed on both sides of fixed electrode 9, and exceeds the horizontal plane 3-5mm of fixed electrode mosaic seat 10, and the height of two emery post 8 is identical, to realize The friction of the rotating electrode sample 7; the inlay material of the fixed electrode mosaic seat 10 is the same as that of the rotating electrode sample 7, and the diameter of the fixed electrode 9 is 1/2 of the diameter of the rotating electrode sample 7, and the two electrodes are kept constant during the test. Concentric; the fixed electrode mosaic seat 10 and the height-adjustable support 12 are provided with a channel 16, the fixed electrode 9 is electrically connected to the copper wire by a spring, and the negative pole of the galvanic corrosion measuring instrument 1 is directly connected to the fixed electrode 9 through a copper wire. The height-adjustable support 12 and the fixed electrode mosaic seat 10 are connected by a high-density threaded screw 13, and the height of the fixed electrode 9 can be adjusted by adjusting the high-density threaded screw 13, so as to adjust the distance between the diamond grinding column 8 and the rotating electrode. The distance controls the friction depth, and the height adjustment range of the high-density threaded screw 13 is 0-50mm, accurate to 0.1mm and can realize fine adjustment.

The test method involved in this embodiment specifically includes three steps of installing the test device, setting the test conditions, controlling the rotating speed and recording the data:

(1) Install the test device: After installing the structural relationship between the rotating electrode system and the fixed electrode system, adjust the height of the height-adjustable support 12 under the fixed electrode 9, and raise the fixed electrode 9 to the diamond grinding column 8 The position in close contact with the rotating electrode sample 7;

(2) Set the test conditions: add the corrosion solution 5 to the corrosion solution tank 11, so that the corrosion solution 5 is submerged in the rotating electrode sample 7;

(3) Control the rotating speed and record data: adjust the rotating speed of the rotating electrode sample 7 through the rotating electrode controller 15, observe the change of the galvanic current at the same time, and record the data accurately.

Specific application examples:

The passive metals commonly used in the industry, pure titanium (TA2) and titanium steel (also known as 316L stainless steel), were selected to carry out the galvanic corrosion test of 316L stainless steel being rubbed under the condition of flowing seawater. Before the test, the rotating electrode of 316L stainless steel was first The sample 7 and the fixed electrode 9 made of metal pure titanium (TA2) are inlaid in the rotating electrode inlay seat 6 and the fixed electrode inlay 10 in a tightly fitting manner respectively, and the height of the adjustable support 12 under the fixed electrode 9 is adjusted , the position of the fixed electrode 9 is raised to the point where the corundum grinding column 8 is in close contact with the rotating electrode sample 7; natural seawater is added to the corrosion solution tank 11 as the corrosion solution 5, so that the natural seawater is not over the rotating electrode sample 7, and by rotating The electrode controller 15 adjusts the rotational speed of the rotating electrode sample 7, and at the same time observes the change of the galvanic current, and records and draws it in detail. The change trend of the galvanic current with the rotational speed is shown in FIG. 2 .

Claims (2)

1. dynamic galvanic corrosion test unit, is characterized in that comprising that bimetallic corrosion measuring instrument, rotor, brush, turning axle, etchant solution, rotation electrode inlay seat, rotation electrode sample, emery grinding column, fixed electorde, fixed electorde and inlay the bearing of seat, etchant solution groove, adjustment height, screw rod, base, rotation electrode controller and the passage of high density screw thread, be divided into rotation electrode system and fixed electorde system two large divisions, wherein the rotation electrode system is by the rotation electrode controller, rotor, turning axle, brush and rotation electrode sample form, Rotation Controllers can realize that rotating speed is continuous adjustable at 0-3000 rev/min, precision is ± 0.01 rev/min, the rotation electrode that the rotation electrode sample that is rubbed adopts close-fitting mode to be embedded in import teflon material is inlayed in seat, make the rotation electrode sample and nonmetallicly inlay between seat corrosion-free medium deeply, inlaid material has the elastic force higher than metal electrode material in addition, therefore can avoid the generation of crevice corrosion, the non-test surfaces center of rotation electrode sample is shaped with threaded hole to realize and being threaded of turning axle, screw thread to screw direction opposite with the sense of rotation of turning axle, after rotation electrode sample and rotation electrode were inlayed seat and turning axle combination, the alignment of testing this assembly, made its excentricity between 0.001-0.005, and the positive pole of bimetallic corrosion measuring instrument is connected with the rotation electrode sample by brush, wherein the fixed electorde system comprises that emery grinding column, fixed electorde inlay bearing and the base of seat, fixed electorde, etchant solution groove, adjustment height, the emery grinding column utilizes seccotine to be fixed on the both sides of fixed electorde, and exceeds fixed electorde and inlay the surface level 3-5mm of seat, and the height of two emery grinding columns is identical, to realize the friction to the rotation electrode sample, it is identical with the inlaid material of rotation electrode sample that fixed electorde is inlayed seat, and the diameter of fixed electorde is that 1/2, two electrode of rotation electrode specimen finish carries out in process remaining concentric in test, fixed electorde is inlayed in seat and the bearing of adjustment height and is provided with passage, be electrically connected to by spring between fixed electorde and copper conductor, the negative pole of bimetallic corrosion measuring instrument directly is connected and fixed electrode by copper conductor, the bearing of adjustment height is inlayed a screw rod by the high density screw thread with fixed electorde and is connected, can regulate the height of fixed electorde by the screw rod of regulating the high density screw thread, in order to regulate the distance between emery grinding column and rotation electrode, control friction depth, the height adjustment range of the screw rod of high density screw thread is 0-50mm, is accurate to 0.1mm and can realizes fine setting.

2. a right to use requires the dynamic galvanic corrosion test method of 1 described device, it is characterized in that comprising the installation test device, test condition is set and controls rotating speed and three steps of record data:

(1) installation test device: after rotation electrode system and fixed electorde system are installed according to the structural relation of routine respectively, regulate the height of the bearing of the adjustment height under fixed electorde, fixed electorde is increased to the position of adamas grinding column and rotation electrode sample close contact;

(2) test condition is set: add etchant solution in the etchant solution groove, make etchant solution not have over-rotation electrode sample;

(3) control rotating speed and record data: regulate the rotating speed of rotation electrode sample by the rotation electrode controller, observe simultaneously the variation of Galvanic Current, and with the data accurate recording.

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