Project implementation of sacrificial anode casting technology for high potential magnesium alloys

Project implementation of sacrificial anode casting technology for high potential magnesium alloys

I. Main Research contents

Ii. Project market analysis

Iii. Project objectives

Based on the existing magnesium alloy sacrifice anodes, a new type of high potential magnesium alloy sacrifice anodes was developed by adjusting the alloy composition and controlling the production process

Iv. Project implementation plan

4.1 Device Solution

Purchase of domestic advanced magnesium alloy casting system, extrusion molding system and anode processing assembly system. The device list is as follows:

Table 4-1 Lists the equipment required by the project

Items for standby use

Name and quantity of system equipment

1 magnesium alloy melting casting system magnesium alloy melting furnace 3 alloy preparation

Magnesium alloy holding furnace 1 alloy standing

Preparation of alloy bar for magnesium alloy casting bar machine 1

Magnesium alloy extrusion system magnesium alloy extruder 2 sacrificial anode extrusion

Lathe bed 2 anode rod processing

Saw machine 1 alloy bar sawing

3 Quality testing system spark spectrum direct reading instrument 1 alloy composition analysis

Potential tester 1 Anode potential test

Resistance tester 1 Test the anode resistance

Observation of microstructure of 1 alloy by optical microscope

4 Environmental protection system waste treatment system 1 Waste gas treatment in smelting process

4.2 Material development and preparation scheme

4.2.1 Alloy composition

Refer to Table 4-2 for the alloy scheme developed by this project. In this alloy scheme, the influence law of each component on the properties of the alloy, such as potential, capacity and current efficiency, is clarified, and each component is adjusted to achieve the best. At the same time, a sacrificial anode alloy with the brand sGYJ-1 and its own intellectual property is developed.

Table 4-2 Sacrificial anode composition of magnesium alloy

Grade composition /%

Alloying element impurity element ≤

Al Zn Mn Mg Fe Ni Cu Si Ca others

A single total

AZ31B 2.5-3.5 0.6-1.4 0.20-1.0 0.003 0.001 0.01 0.08 0.04 0.05 0.30

AZ63B 5.3-6.7 2.5-3.5 0.15-0.60 allowance 0.003 0.001 0.01 0.08 - -0.30

M1C ≤ 0.01-0.50-1.30 allowance 0.01 0.001 0.01 0.08-0.05 0.30

Sgyj-1 ≤0.01 0.0-0.4 0.0-0.50 allowance 0.002 0.001 0.005 0.02-0.005 0.20

4.2.2 Ingredients for magnesium alloy production

The accuracy of the batching in magnesium alloy production will affect the composition of the alloy, which in turn will affect the final properties of the alloy, so the batching in the alloy production is a major matter related to the quality of the final alloy. Taking a 2.5-ton crucible with a discharge of 2.0ton each time as an example, the ingredients of various alloys are listed below.

Table 4-3 Different alloy ingredients (calculated according to 2.0ton discharge per furnace)

Raw materials Amount of raw materials of various alloys (Kg)

AZ31B AZ63B M1C

1 Mg 1934.1 1818.8 1999.0

2 Al 57.1 121.2 2.0

3 Zn 15.0 60.0 -

4 MnClB2B 23.0 34.0 72.0

5 Al-Be(1%Be) 3.0 - -

6 Melting flux 50.0 50.0 50.0

7 Refining flux 60.0 60.0 60.0

4.2.3. Technological process for the preparation of magnesium alloy

Figure 4-1 shows the temperature and time curve of the alloy when the alloy melting system is used to prepare the sacrificial anode of magnesium alloy. The working curves of different alloys and melting systems are different, but the basic trend and process are much the same.

When preparing the refined pure magnesium liquid into the alloy crucible or directly add pure magnesium ingots, and heating up to 740℃, this process to continuously sprinkle the melting flux to prevent the melting soup fire. When the melt temperature reaches 720℃, aluminum, zinc, aluminum beryllium alloy and other metallic elements are added successively. When the melt temperature reaches 740℃, the preheated stirring device is slowly placed into the melt to start refining and stirring, and MnClB2B particles and refining flux are added at the same time. Refining generally lasts 30 minutes to ensure that all impurities in the melt are complexed with the flux. After refining, take out the agitator and turn off the heating device, and start to cool down to 660℃. After the impurity content in the melt settles to a certain index, the alloy composition shall be tested, and the melt shall be transferred to the holding furnace if qualified.

Figure 4-1 AZ91D production process diagram

After the qualified magnesium liquid in the holding furnace is standing, it can be poured into the ingot mold and directly cast as the MAGNESIUM alloy D-type anode, or it can be pulled and cast as the magnesium alloy bar and then extruded into the magnesium alloy anode.

When casting rods, the cooling circulating water system of the casting rod machine should be opened first, and the magnesium liquid is driven into the mold of the casting rod system by the casting pump. Meanwhile, the primer head is slowly moved downward to pull the magnesium alloy bar.

After the magnesium bar is finished, it is lifted out of the casting well with a crane and transported to the cutting workshop for sawing and peeling to the size of φ 100×500mm.

The extrusion die is preheated and installed on the extruder, and the heated magnesium alloy rod is put into the ingot barrel of the extruder to extrude the magnesium alloy anode of corresponding size.

4.3 Testing scheme for magnesium alloy anodes

Table 4-5 lists the test scheme for magnesium alloy anodes.

Table 4-5 Test items and solutions for magnesium alloy anodes

Item Detection Method Remarks

Alloy component spark spectrometers require calibration of standard samples of all grades of alloy

The calomel electrode was used as the reference electrode

3 Contact resistance test resistance tester can be homemade

The size of the anode varies with the size of the anode, such as the vernier calipers, micrometers and meter sticks

4.4 Research direction and control objectives

4. 4.1 Electrochemical performance

The electrochemical performance requirements of the alloys developed in trial production are shown in Table 4-4, and the telephone performance of the alloys developed independently is expected to achieve higher performance.

Table 4-4 Electrochemical performance of magnesium alloy sacrificial anodes

Alloy grade open circuit potential

-v, Cu/CuSO4 closed circuit potential

-v,Cu/CuSO4 Actual capacitance /

(A●h/Kg) Current efficiency /

%

AZ31B 1.57-1.67 1.47-1.57 ≥1210 55

AZ63B 1.57-1.67 1.52-1.57 ≥1210 55

M1C 1.77-1.82 1.64-1.69 ≥1100 50

Sgyj-1 1.80-1.90 1.75-1.85 ≥1210 55

4. 4.2 Contact resistance

The contact resistance between magnesium alloy and steel core is required to be less than 0.001 ω.