Apparatus and method for identifying metal corrosion

Abstract

An apparatus for identifying metal corrosion includes a metal test piece, a push button timer, a liquid tank, a support, two fixed pulleys, a traction cable, a weight and a vibration motor. The support and the first pulley are in a lower portion of the tank. The second pulley is above the first pulley. The test piece is fixed on the support and connected to a first end of the traction cable which sequentially winds around the pulleys with a second end outside the tank. The weight, on which the motor is fixed, is suspended at the second end. The timer is under the motor. A corrosion solution is added into the tank, and the vibration motor provides alternating stress. When the metal test piece is broken, the weight and the motor are dropped and pressed on the electronic timer to record breaking time of the metal test piece.

Claims

1. An apparatus for identifying metal corrosion, comprising: a metal test piece (1), a timer (10), a tensioning device and a liquid tank (2), the tensioning device further comprising a support (3), a first fixed pulley (11), a second fixed pulley (4), a traction cable (5), a weight and a vibration motor (6); wherein the support (3) is fixed within a lower portion of the liquid tank (2) on one side thereof, the first fixed pulley (11) is fixed within the lower portion of the liquid tank (2) on the other side thereof, and the second fixed pulley (4) is fixed on the upper end of a side wall of the liquid tank (2) on the side of the first fixed pulley (11); the metal test piece (1) is fixed on the support (3) at one end thereof, and connected to a first end of the traction cable (5) at the other end thereof; the traction cable (5) sequentially winds around the first fixed pulley (11) and the second fixed pulley (4), a second end of the traction cable (5) is located outside the liquid tank (2) and the weight, on which the vibration motor (6) is fixed, is suspended at the second end of the traction cable (5); and the timer (10) is a push button type electronic timer that is disposed directly under the vibration motor (6).

2. The apparatus for identifying metal corrosion according to claim 1, wherein the weight comprises a load (7) and a load hanger (8), the load hanger (8) is suspended at the second end of the traction cable (5), and the vibration motor (6) is attached to the bottom surface of the load hanger (8).

3. The apparatus for identifying metal corrosion according to claim 2, wherein a ring (17) is provided on the second end of the traction cable (5), and the load (7) and the load hanger (8) are suspended on the ring (17).

4. The apparatus for identifying metal corrosion according to claim 3, wherein the metal test piece (1) is fixed, at one end thereof, to the support (3) by a non-metallic fastening bolt (14), and is connected to the first end of the traction cable (5) by a lightweight non-metallic double-headed screw bolt (12) at the other end thereof.

5. The apparatus for identifying metal corrosion according to claim 4, wherein the metal test piece (1) is a metal wire.

6. The apparatus for identifying metal corrosion according to claim 5, wherein the push button type electronic timer is further provided with a shockproof sponge (9) at the top surface thereof.

7. The apparatus for identifying metal corrosion according to claim 6, wherein the support (3), the first fixed pulley (11), the second fixed pulley (4), and the liquid tank (2) are non-metallic components.

8. The apparatus for identifying metal corrosion according to claim 7, wherein the traction cable (5) is made of high-strength fiber.

9. The apparatus for identifying metal corrosion according to claim 8, wherein a plurality of parallel tensioning devices are arranged in the liquid tank (2), and in the plurality of sets of parallel tensioning devices, the metal test piece (1) with any physical property is disposed to perform identification of various metal corrosions and corrosion rates.

10. An identification method using the apparatus for identifying metal corrosion according to claim 9, comprising the steps of: step 1: arranging the liquid tank (2), arranging the support (3) and the first fixed pulley (11) in the liquid tank (2), and fixing the second fixed pulley (4) to the upper end of the side wall of the liquid tank on the side of the first fixed pulley (11); step 2: fixing one end of the metal test piece (1) on the support (3), connecting the other end thereof with the first end of the traction cable (5); winding the traction cable (5) around the first fixed pulley (11) and the second fixed pulley (4) sequentially, disposing, outside the liquid tank (2), the second end of the traction cable (5) on which the weight is suspended, and attaching the vibration motor (6) on the weight; step 3: setting the vibration frequency of the vibration motor (6) such that the vibration motor (6) and the weight together generate a low-frequency alternating tension; wherein, the vibration frequency θ of the vibration motor (6) is changed by suspending the weight having a weight of ΔG and the vibration motor (6) having a weight of G.sub.1 under the ring (17) arranged on the second end of the traction cable (5); step 4: injecting the corrosion solution to be studied into the liquid tank (3) to carry out the corrosion test; simultaneously, returning the button type electronic timer arranged vertically below the weight to zero as the test starting point; step 5: visually inspecting the occurrence of initial rust spots of the metal test piece (1) in the corrosion solution, and recording the time displayed on the button type electronic timer as t.sub.s; step 6: leaving the metal test piece (1) to corrode continuously, and once the metal test piece (1) is broken by corrosion, recording the breaking time t.sub.r in such a manner that the weight and the vibration motor (6) suspended at the lower end of the ring (17) fall perpendicularly to the button of the button type electronic timer; wherein the button type electronic timer is provided with the shockproof sponge (9) at the top surface thereof; when the metal test piece (1) is broken by corrosion, $\begin{array}{cc}{A}_1=\frac{F}{\left[\sigma \right]}& \left(1\right)\end{array}$ where [σ] is tensile strength of the metal test piece,
F=β.Math.G  (2) is the maximum value of the alternating tension with a vibration frequency of θ, where
G=G.sub.1+ΔG  (3) and is the sum of the weight G.sub.1 of the vibration motor (6) and the weight ΔG of the weight; wherein the vibration motor (6) is attached to the bottom surface of the load hanger (8), and the total weight can be changed by increasing or decreasing the weight ΔG on the load hanger 8, and $\begin{array}{cc}\beta =\frac{1}{1-{\theta }^2/{\omega }^2}& \left(4\right)\end{array}$ is a dynamic coefficient, where ω is a natural frequency of a single-degree-of-freedom system composed of the metal test piece (1), the traction cable (5) and the weight G, since the metal test piece (1) and the traction cable (5) are in a series structure in the apparatus for identifying, as actually measured or structural mechanics theory calculated, which can be calculated as follows: $\begin{array}{cc}{k}_1=\sqrt{\frac{E_1{A}_1}{l_1}}& \left(5\right)\\ k_2=\sqrt{\frac{E_2{A}_2}{l_2}}& \left(6\right)\\ k=\frac{1}{k_1}+\frac{1}{k_2}=\frac{k_1{k}_2}{k_1+k_2}& \left(7\right)\\ \omega =\sqrt{\frac{k}{m}}=\sqrt{\frac{\mathrm{kg}}{G}}& \left(8\right)\end{array}$ where, E.sub.1 and E.sub.2 are Young's modulus of the metal test piece (1) and the traction cable (5) respectively, A.sub.1 and A.sub.2 are cross-sectional areas of the metal test piece (1) and the traction cable (5) respectively, l.sub.1 and l.sub.2 are horizontal lengths of the metal test piece (1) and the traction cable (5) respectively, and g=9.80665 m/s.sup.2 and is acceleration of gravity; wherein, the corrosion rate V of the metal test piece (1) is obtained by the following equation: $\begin{array}{cc}V=\frac{A_0-A_1}{t_r-t_s}& \left(9\right)\end{array}$ where A.sub.0 is cross-sectional area of the metal test piece, A.sub.1 is cross-sectional area at the time of breaking of the metal test piece, and t.sub.s is occurrence time of the initial rust spot in the metal test piece, and t.sub.r is breaking time of the metal test piece; step 7: performing various operating condition tests simultaneously with the plurality of sets of parallel tensioning devices in the liquid tank (2) according to the steps above.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic structural view of an apparatus for identifying metal corrosion according to the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(2) The present invention will be further described in detail below with reference to FIG. 1 and specific embodiments.

(3) An apparatus for identifying metal corrosion includes a metal test piece 1, a timer 10, a tensioning device and a liquid tank 2, and the metal test piece 1 is a metal wire. The tensioning device further includes a support 3, a first fixed pulley 11, a second fixed pulley 4, a traction cable 5, a weight and a vibration motor 6. The support 3 is fixed within a lower portion of the liquid tank 2 on one side thereof, the first fixed pulley 11 is fixed within the lower portion of the liquid tank 2 on the other side thereof, and the second fixed pulley 4 is fixed on the upper end of a side wall of the liquid tank 2 on the side of the first fixed pulley 11. The metal test piece 1 is fixed on the support 3 at one end thereof by means of a non-metallic fastening bolt 14, and connected to a first end of the traction cable 5 at the other end thereof by means of a lightweight non-metallic double-headed screw bolt 12. The traction cable 5 sequentially winds around the first fixed pulley 11 and the second fixed pulley 4, a second end of the traction cable 5 is located outside the liquid tank 2 and the weight, on which the vibration motor 6 is fixed, is suspended at the second end of the traction cable 5. The vibration motor 6 can be set to any vibration frequency. The weight comprises a load 7 and a load hanger 8, the load hanger 8 is suspended at the second end of the traction cable 5, and the vibration motor 6 is attached to the bottom surface of the load hanger 8. A ring 17 is provided on the second end of the traction cable 5, and the load 7 and the load hanger 8 are suspended. The timer 10 is a push button type electronic timer that is disposed directly under the vibration motor 6. The push button type electronic timer is further provided with a shockproof sponge 9 at the top surface thereof.

(4) In the apparatus, the support 3, the first fixed pulley 11, the second fixed pulley 4 and the liquid tank 2 are all made of a non-metallic member, and the first fixed pulley 11 and the second fixed pulley 4 have a small diameter and a smooth surface, and therefore reduced friction due to contact with the traction cable 5. The traction cable 5 is made of a high-strength fiber. In addition, a plurality of parallel tensioning devices can be arranged in the liquid tank 2, and the metal test piece 1 with any physical properties, including any mechanical properties, any cross-section dimensions and the like, can be disposed in the plurality of sets of parallel tensioning devices to perform identification of various metal corrosions.

(5) An identification method using the apparatus for identifying metal corrosion described above includes the steps of:

(6) step 1: arranging the liquid tank 2, arranging the support 3 and the first fixed pulley 11 in the liquid tank 2, and fixing the second fixed pulley 4 to the upper end of the side wall of the liquid tank on the side of the first fixed pulley 11;

(7) step 2: fixing one end of the metal test piece 1 on the support 3, connecting the other end thereof with the first end of the traction cable 5; winding the traction cable 5 around the first fixed pulley 11 and the second fixed pulley 4 sequentially, disposing, outside the liquid tank 2, the second end of the traction cable 5 on which the weight is suspended, and attaching the vibration motor 6 on the weight;

(8) step 3: setting the vibration frequency of the vibration motor 6 such that the vibration motor 6 and the weight together generate a low-frequency alternating tension; wherein, the vibration frequency θ of the vibration motor 6 is changed by suspending the weight having a weight of ΔG and the vibration motor 6 having a weight of G1 under the ring 17 arranged on the second end of the traction cable 5;

(9) step 4: injecting the corrosion solution to be studied into the liquid tank 3 to carry out the corrosion test; simultaneously, returning the button type electronic timer arranged vertically below the weight to zero as the test starting point;

(10) step 5: visually inspecting the occurrence of initial rust spots of the metal test piece (1) in the corrosion solution, and recording the time displayed on the button type electronic timer as t.sub.s;

(11) step 6: leaving the metal test piece 1 to corrode continuously, and once the metal test piece 1 is broken by corrosion, recording the breaking time t.sub.r in such a manner that the weight and the vibration motor 6 suspended at the lower end of the ring 17 fall perpendicularly to the button of the button type electronic timer; wherein the button type electronic timer is provided with the shockproof sponge 9 at the top surface thereof;

(12) when the metal test piece 1 is broken by corrosion,

(13) $\begin{array}{cc}{A}_1=\frac{F}{\left[\sigma \right]}& \left(1\right)\end{array}$

(14) where [σ] is tensile strength of the metal test piece,
F=β.Math.G  (2)
is the maximum value of the alternating tension with a vibration frequency of θ, where
G=G.sub.1+ΔG  (3)
and is the sum of the weight G.sub.1 of the vibration motor 6 and the weight ΔG of the weight; wherein the vibration motor 6 is attached to the bottom surface of the load hanger 8, and the total weight can be changed by increasing or decreasing the weight ΔG on the load hanger 8, and

(15) $\begin{array}{cc}\beta =\frac{1}{1-{\theta }^2/{\omega }^2}& \left(4\right)\end{array}$
is a dynamic coefficient, where ω is a natural frequency of a single-degree-of-freedom system composed of the metal test piece 1, the traction cable 5 and the weight G, since the metal test piece 1 and the traction cable 5 are in a series structure in the apparatus for identifying, as actually measured or structural mechanics theory calculated, which can be calculated as follows:

(16) $\begin{array}{cc}{k}_1=\sqrt{\frac{E_1{A}_1}{l_1}}& \left(5\right)\\ k_2=\sqrt{\frac{E_2{A}_2}{l_2}}& \left(6\right)\\ k=\frac{1}{k_1}+\frac{1}{k_2}=\frac{k_1{k}_2}{k_1+k_2}& \left(7\right)\\ \omega =\sqrt{\frac{k}{m}}=\sqrt{\frac{\mathrm{kg}}{G}}& \left(8\right)\end{array}$

(17) where, E.sub.1 and E.sub.2 are Young's modulus of the metal test piece 1 and the traction cable 5 respectively, A.sub.1 and A.sub.2 are cross-sectional areas of the metal test piece 1 and the traction cable 5 respectively, l.sub.1 and l.sub.2 are horizontal lengths of the metal test piece 1 and the traction cable 5 respectively, and g=9.80665 m/s.sup.2 and is acceleration of gravity.

(18) The corrosion rate V of the metal test piece 1 is obtained by the following equation:

(19) $\begin{array}{cc}V=\frac{A_0-A_1}{t_r-t_s}& \left(9\right)\end{array}$

(20) where A.sub.0 is cross-sectional area of the metal test piece, A.sub.1 is cross-sectional area at the time of breaking of the metal test piece, and t.sub.s is occurrence time of the initial rust spot in the metal test piece, and t.sub.r is breaking time of the metal test piece;

(21) step 7: performing various operating condition tests simultaneously with the plurality of sets of parallel tensioning devices in the liquid tank 2 according to the steps above.

(22) The above embodiment of the invention demonstrates that the apparatus for identifying metal corrosion according to the invention has simple configuration and operation, and high test efficiency, and can be used to identify the metal corrosion under the action of alternating stress and the corrosion rate of the metal under the alternating stress. The above apparatus can also be used for studying the issue on passivation effect under alternating stress.

(23) The above-mentioned embodiment is only for the purpose of illustrating the technical solutions of the invention, and is not intended to limit the present invention. The modification made by those skilled in the art based on common knowledge in the art, are also incorporated in the scope of the application. In the meantime, the above-described embodiment is merely illustrative, and the scope of the application is defined by the scope of the appended claims.