JP2006090712A - Corrosion tester - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact corrosion tester for rapidly performing a corrosion test to evaluate corrosion resistance of a member for a heat exchanger under conditions close to a natural environment. <P>SOLUTION: This corrosion tester comprises a corrosive liquid spraying means for giving a collision jet to a surface of a test piece immersed in a corrosive liquid, a corrosive liquid supplying means for supplying the corrosive liquid to the spraying means, a cooling/heating means for controlling the temperature of the corrosive liquid, and a heating or cooling means for controlling the temperature of the test piece. The supplying means is equipped with a nozzle adjustment mechanism for adjusting a gap between a surface of the test piece and an end of a nozzle. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a corrosion test apparatus that performs a corrosion test under a condition in which corrosion is accelerated more than the natural environment, and more particularly to a corrosion test apparatus that performs a corrosion test using a collision jet at a controlled corrosive liquid temperature and test piece temperature.

  Aluminum alloys, copper alloys, and the like are widely used as heat exchanger members because of their high thermal conductivity and excellent workability. Since such a heat exchanger member is in contact with a fluid medium that exchanges heat for a long time, damage due to corrosion that occurs through the fluid medium becomes a problem.

  There is a need for a corrosion test apparatus that can quickly evaluate the corrosion resistance of members for heat exchangers under conditions close to the natural environment against such corrosion problems. For example, Patent Documents 1 and 2 propose an alkaline side corrosion tester for studying automobile radiator materials. Patent Document 3 proposes a corrosion test apparatus for evaluating the corrosion resistance of aluminum alloy materials such as water pumps and thermostats used in automobile engines. In other words, in a metal surface corrosion test apparatus that investigates the corrosion status of metal surfaces by immersing metal test pieces in the corrosion liquid, the corrosion liquid is forcedly circulated and the corrosion liquid is allowed to flow toward the metal test piece surface. Thus, a forced convection metal surface corrosion test apparatus characterized by applying a dynamic pressure to the surface of a metal specimen has been proposed.

  Further, Patent Document 4 discloses a simulated environment that simulates the environment that a heat exchanger actually receives as a corrosion test apparatus for evaluating the corrosion resistance of an Al alloy material used for a heat exchanger member of a liquefied natural gas vaporizer. A corrosion test apparatus has been proposed in which a test piece immersed in artificial seawater at a predetermined temperature is rotated at a high speed so that a corrosion test can be carried out.

JP 11-209838 A JP 2000-96169 A JP 2001-133389 A JP 11-106889 A

  However, the corrosion test apparatus as proposed above has a problem that the corrosion test still takes time and a rapid corrosion test cannot be performed. In addition, there is a problem that the corrosion test apparatus tends to be large and the corrosion test cannot be easily performed.

  In view of such problems, the present invention has an object to provide a compact corrosion test apparatus that can quickly perform a corrosion test for evaluating the corrosion resistance of a heat exchanger member under conditions close to the natural environment. And

  The present inventor noted that the damage caused by corrosion is caused by the formation of a corrosion film, the destruction / peeling of the film being repeated, and the corrosion progressing one after another. The present invention was completed by obtaining the knowledge that the formation and delamination were accelerated and a rapid corrosion test was possible.

  A corrosion test apparatus according to the present invention includes a corrosive liquid ejecting means for applying a collision jet to the surface of a test piece immersed in the corrosive liquid, a corrosive liquid supplying means for supplying the corrosive liquid to the corrosive liquid ejecting means, A cooling / heating means for controlling the temperature, and a cooling or heating means for controlling the temperature of the test piece, and the corrosive liquid supply means comprises a nozzle adjusting mechanism for adjusting a clearance between the test piece and the nozzle. Become.

  In the above invention, the nozzle adjusting mechanism holds the nozzle for injecting the corrosive liquid toward the test piece so as to face the test piece on the upper base provided apart from the lower base having the test piece holding means. It is preferable that a means for moving back and forth in the direction of the test piece and a gap measuring means for measuring a gap between the test piece and the nozzle are provided.

  Moreover, it is preferable to use a Peltier element as a cooling means for controlling the temperature of the test piece, and a power supply device capable of allowing a predetermined current to flow between the test piece immersed in the corrosive liquid and the counter electrode is provided. Is preferred.

  The corrosion test apparatus according to the present invention is a compact apparatus, and can quickly perform a corrosion test for evaluating the corrosion resistance of a heat exchanger member under conditions close to the natural environment.

  An embodiment of a corrosion test apparatus according to the present invention will be described with reference to FIGS. FIG. 1 is a schematic diagram for explaining the layout of the present corrosion test apparatus, and FIG. 2 is an enlarged cross-sectional view of a corrosive liquid injection means portion of the corrosion test apparatus. As shown in FIG. 1, this corrosion test apparatus has a corrosive liquid injection means 10, a corrosive liquid supply means 6, a corrosive liquid cooling / heating means 4, and a test piece cooling means 20 or a heating means 25. A corrosion test using a collision jet of a corrosive liquid at a predetermined temperature can be performed on the surface of the test piece 60 held at the predetermined temperature.

  As shown in FIG. 1, the corrosive liquid injection means 10 is installed in a state where the end of the nozzle and the surface of the test piece 60 are immersed in the corrosive liquid in the corrosion test tank 2. As shown in FIG. 2, the corrosive liquid injection means 10 includes a lower base 11 that holds the test piece 60, and an upper base 12 that is screw-coupled to the lower base 11 and spaced apart from the lower base 11 by a predetermined distance. And the nozzle 15 is configured to face the test piece 60 and to move back and forth in the direction of the test piece 60. In other words, the nozzle 15 is connected to the adjustment handle 14 that is rotatably attached to the upper base 12 via the adjustment handle base 13 fixed to the upper base 12 by screw connection, and the rotation of the adjustment handle 14 Thus, the nozzle 15 moves up and down in FIG. 2 so that the clearance between the test piece 60 and the nozzle 15 can be adjusted. The adjustment handle 14 is rotatably coupled by an adjustment handle base 13 and a snap ring 35.

  The clearance between the test piece 60 and the nozzle 15 is measured by the clearance measuring means 18. The clearance measurement is performed, for example, by measuring the amount of vertical movement in FIG. 2 of the measurement plate 181 fixed to the pipe 17 integrally connected to the nozzle 15 by a known displacement meter. The gap between the test piece 60 and the nozzle 15 can be adjusted with high accuracy, for example, in the range of 0.1 to 1 mm, by the nozzle adjusting mechanism using the gap measuring means 18 and the above-described nozzle screw adjustment.

  The nozzle 15 has pores 151 and can inject the corrosive liquid supplied through the pipe 17 onto the surface of the test piece 60. The diameter of the pores 151 is related to the amount of the corrosive liquid to be supplied, the size of the corroded surface of the test piece 60, etc., but is preferably about 1.0 to 2.0 mm.

  The pipe 17 passes through the adjustment handle 14 and is coupled to the nozzle 15 by screw coupling, and the distal end portion of the pipe 17 is closely fixed to the contact seat surface of the nozzle 15. The threaded portion between the pipe 17 and the nozzle 15 is sealed with a sealing tape or a taper screw to ensure the sealing performance of the threaded portion. Similarly, an O-ring seal 33 is provided to ensure the sealing performance between the nozzle 15 and the upper base 12. Further, a gasket 31 is provided to ensure a sealing property between the upper base 12 and the test piece 60 mounting portion.

  As shown in FIG. 1, the corrosive liquid supply means 6 includes a pump 41, a flow rate adjusting valve 42, a flow meter 43, and a pipe 44 that communicates the corrosive test tank 2 containing the corrosive liquid and the thermostatic chamber 45. . A well-known thing can be used for the pump 41, the flow regulating valve 42, and the flow meter 43. The corrosive liquid controlled to a predetermined temperature in the thermostatic chamber 45 by the corrosive liquid supply means 6 is supplied to the predetermined flow corrosive liquid injection means 10 via the pump 41, the flow rate adjusting valve 42, and the flow meter 43, and is supplied by the nozzle 15. After being sprayed on the test piece 60, it returns to the thermostat 45 through the corrosion test tank 2 and is subjected to recirculation.

  The cooling / heating means 4 for the corrosive liquid preferably includes a cooler 47 and a heater 46. Thereby, the corrosive liquid in the thermostat 45 can be maintained at a constant temperature regardless of the test temperature of the test piece 60. However, when the temperature of the corrosive liquid can be controlled only by the cooler 47 or the heater 46, such as when the heat capacity of the corrosive liquid is large and the heat capacity of the test piece 60 is small, either the cooler 47 or the heater 46 may be provided. Known coolers 47 and heaters 46 can be used.

  As the cooling means 20 for the test piece 60, a known means can be used. However, when a Peltier element is used as the cooling means 20, the test piece cooling means 20 that is compact and easy to control the temperature can be configured. FIG. 2 shows an embodiment using Peltier elements. In this example, the Peltier element 21 is attached to the lower base 11 by the cover 16 via the gasket 23 and the presser lid 24 with the upper surface closely attached to the test piece 60 and the lower surface closely attached to the cooling block 22 having the water cooling holes 221. ing.

  As the heating means 25 of the test piece 60, a known one can be used. For example, the heating means 25 can be easily configured by incorporating a known sheath heater. The Peltier element can also be used.

  With the above configuration, in this corrosion test apparatus, the hole diameter of the pore 151 of the nozzle 15 is 1.0 to 2.0 mm, the clearance between the test piece 60 and the nozzle 15 is 0.1 to 1 mm, and the flow rate of the corrosive liquid is 0.025 to 1 L / min. Under the conditions described above, the corrosive liquid can be jetted onto the test piece to perform the corrosion test by the impinging jet. Under such conditions, in addition to promoting the formation and peeling of the corrosion film by the impinging jet, a macrocell is formed between the central portion and the outer peripheral portion of the test piece 60, so that the anode reaction occurs in the central portion of the test piece 60. Since the cathode reaction is further promoted at the outer periphery, a rapid corrosion test can be performed. The macro cell is formed because the flow rate of the corrosive liquid is very different between the central portion and the peripheral portion where the corrosive liquid directly hits. For example, when the surface of the test piece 60 has a diameter of 16 mm, the flow rate ratio between the central portion and the peripheral portion of the test piece 60 becomes about 10 times.

Although the present corrosion test apparatus has been described above, the present invention is not limited to the above-described embodiment. For example,
As shown in FIG. 1, it is preferable to provide a power supply device 50 such as a potentiostat, a counter electrode 51, and a standard electrode 53. Accordingly, since a predetermined current can be passed between the test piece 60 and the counter electrode 51 to further accelerate the corrosion, a rapid corrosion test can be performed. Further, the corrosion state of the test piece 60 can be investigated by measuring the potential between the standard electrode 53 and the test piece 60 and measuring the polarization curve.

  Also, it is preferable to provide means for mixing air into the corrosive liquid. Thereby, the corrosion test can be performed under conditions closer to the natural environment. For example, as shown in FIG. 1, air mixing into the corrosive liquid can be performed by supplying air from the compressor to the corrosive liquid in the thermostatic bath 45 through the air supply pipe 48.

  Further, the corrosion test apparatus can be used to perform the corrosion test by reversely circulating the corrosive liquid in the direction from the flow path 152 of the corrosive liquid injection means 10 to the pore 151 of the nozzle 15 and the pipe 17. Thereby, a vortex is generated at the center of the test piece 60, and a corrosion test under the vortex can be performed.

  In this corrosion test apparatus, the corrosion test layer 2 and the constant temperature bath 45 can be provided integrally. In order to facilitate replacement of the test piece 60, switching is performed as shown in FIG. A valve 19 can also be provided. Further, in the corrosive liquid injection means 10, the clearance between the test piece 60 and the nozzle 15 can be adjusted so that the test piece 60 moves forward and backward. However, since the heating / cooling means 4 is generally provided on the side of the test piece in contact with the test piece 60 and has a complicated structure, it is preferable that the nozzle 15 be moved forward and backward as described above.

  In addition, this corrosion test apparatus can be used not only for the corrosion test of the members for heat exchangers, such as an aluminum alloy and a copper alloy, but also for the corrosion test of various materials. For example, it can also be used for corrosion tests of steel materials.

  A corrosion test was conducted to evaluate the corrosion resistance of the aluminum alloy in the heat exchanger part of the open rack vaporizer that vaporizes liquefied natural gas using seawater. The corrosion test was performed under conditions that mimic the actual environment of the heat exchanger. That is, the corrosion test apparatus having the structure shown in FIGS. 1 and 2 was used, the hole diameter of the nozzle hole 151 was 1.6 mm, and the clearance between the test piece 60 and the nozzle 15 was 0.4 mm. The test piece 60 was made of an Al—Mg-based A5083 alloy and has a stepped columnar shape as shown in FIGS. 1 and 2, and its corrosion side surface had a diameter of 16 mm and a total weight of about 5 g. As the corrosive solution, artificial seawater (Aquamarine for metal corrosion test, 20 L, manufactured by Yashima Co., Ltd.) having a dissolved oxygen amount of 6.9 ppm (measured with DOMETER DOL-10 manufactured by DDK at 20 ° C.) was used. The flow rate of the artificial seawater was 0.4 L / min, the temperature was kept at 30 ° C., and the pH was kept at 8.2. The test piece 60 was held at 7 ° C. (the surface temperature of the portion where the Peltier element was in contact with the test piece 60 was measured with a thermocouple) at the temperature of the Peltier element surface. The corrosion test time was 20h. As a comparative example, a corrosion test was performed using a corrosion test apparatus similar to the apparatus proposed in JP-A-11-106889.

  The corrosion resistance was evaluated by measuring the mass loss of the test piece 60 and measuring the erosion depth. Mass measurement was performed using Mettler's AE163 having a measurement accuracy of 0.01 g, and erosion depth measurement was performed using a surface roughness and shape measuring machine Cercom 200B manufactured by Tokyo Seimitsu Co., Ltd. As a result of the above corrosion test, according to this corrosion test apparatus, the mass defect was 1.01 mg, and the maximum erosion depth of the sample surface was 6 μm. With the corrosion test apparatus according to the comparative example, changes in mass defect and surface roughness could not be measured.

It is a schematic diagram explaining the layout of the corrosion test apparatus which concerns on this invention. It is an expanded sectional view of the corrosive liquid injection means part of FIG.

Explanation of symbols

2 Corrosion test tank
4 Cooling / heating means
6 Corrosion liquid supply means
10 Corrosion solution injection means
11 Lower base
12 Upper base
13 Adjustment handle base
14 Adjustment handle
15 nozzles
151 pores
16 Cover
17 Piping
18 Clearance measurement method
181 measuring plate
19 Switching valve
20 Cooling means
21 Peltier element
22 Cooling block
221 Water cooling hole
23 Gasket
24 Holding lid
25 Heating means
31 Gasket
33 O-ring seal
35 Snap ring
41 pump
42 Flow control valve
43 Flow meter
44 Piping
45 Thermostatic bath
46 Heater
47 cooler
48 Air supply pipe
50 Power supply
51 counter electrode
53 Standard electrode
60 specimens

Claims (4)

A corrosive liquid jetting means for applying a collision jet to the surface of the test piece immersed in the corrosive liquid; a corrosive liquid supply means for supplying the corrosive liquid to the corrosive liquid jetting means; and a cooling / heating means for controlling the temperature of the corrosive liquid; A cooling or heating means for controlling the temperature of the test piece,
The corrosive liquid supply means is a corrosion test apparatus provided with a nozzle adjustment mechanism for adjusting a gap between the test piece and the nozzle. The nozzle adjustment mechanism
In the upper base provided apart from the lower base having the test piece holding means,
Means for holding the nozzle for spraying the corrosive liquid toward the test piece so as to face the test piece and moving the nozzle back and forth in the direction of the test piece;
The corrosion test apparatus according to claim 1, further comprising a gap measuring unit that measures a gap between the test piece and the nozzle.   The corrosion test apparatus according to claim 1 or 2, wherein the cooling means for controlling the temperature of the test piece uses a Peltier element.   The corrosion test apparatus according to any one of claims 1 to 3, further comprising a power supply device capable of causing a predetermined current to flow between the test piece immersed in the corrosive liquid and the counter electrode.

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