A corrosion-resistant Pb-Ag-Al alloy material and its preparation method

Abstract

The present invention belongs to the technical field of the preparation of non-ferrous metal materials, and particularly relates to a corrosion-resistant Pb-Ag-Al alloy material and a preparation method thereof. A highly corrosion-resistant Pb-Ag-Al alloy material, by weight percentage, has a formulation ratio as follows: silver 0.5 to 2.0%, aluminum 0.15 to 0.8%, and the balance is lead. The preparation method includes 1) melting the weighed pure lead by using an electric resistance furnace or an induction melting furnace, and adjusting the melt temperature to 750 to 1000 °C; 2) adding the weighed silver and aluminum elements into the melt; 3) fully stirring the alloy melt and keeping it warm for 20-30 min to form a homogeneous melt; 4) cooling and solidifying the alloy melt by using a casting or continuous solidification technique to obtain the Pb-Ag-Al alloy material. The Pb-Ag-Al alloy material prepared by the present invention has excellent corrosion resistance and has great application prospects in the fields of hydrometallurgy and energy, etc.

Description

Technical Field

[0001] The present invention belongs to the technical field of non-ferrous metal material preparation, and particularly relates to a corrosion-resistant Pb-Ag-Al alloy material and a preparation method thereof. Background Technique

[0002] Pb-Ag alloy is a commonly used anode material in the electrolysis process of non-ferrous alloys such as zinc, copper, and nickel. However, the electrolysis process of non-ferrous alloys such as zinc, copper, and nickel is usually carried out in an acidic environment, which has high requirements for the corrosion resistance of electrode materials. Therefore, it is of great significance to develop electrode materials with high corrosion resistance and excellent catalytic activity. Summary of the Invention

[0003] Aiming at the problems in the prior art, the present invention provides a corrosion-resistant Pb-Ag-Al alloy material and a preparation method thereof. The alloy is mainly composed of a Pb matrix and a (Ag, Al)-rich second phase, and has more excellent corrosion resistance than the currently industrial Pb-1Ag alloy.

[0004] The technical solution of the present invention is as follows:

[0005] A highly corrosion-resistant Pb-Ag-Al alloy material, by weight percentage, its formulation ratio is: silver 0.5 - 2.0%, aluminum 0.15 - 0.8%, and the balance is lead.

[0006] Further, for the above-mentioned highly corrosion-resistant Pb-Ag-Al alloy material, the alloy material structure is composed of a Pb matrix and a (Ag, Al)-rich second phase, and the size of the second phase is between several microns and dozens of microns.

[0007] Further, for the above-mentioned highly corrosion-resistant Pb-Ag-Al alloy material, the (Ag, Al)-rich second phase in the alloy material presents a shell / core structure, where the shell layer of the second phase is rich in Ag element and the core is rich in Al element.

[0008] Further, for the above-mentioned highly corrosion-resistant Pb-Ag-Al alloy material, the corrosion rate of the alloy material in sulfuric acid solution is reduced by more than 54% compared with the Pb-1Ag alloy.

[0009] A preparation method of the above-mentioned highly corrosion-resistant Pb-Ag-Al alloy material includes the following steps:

[0010] 1) Use an electric resistance furnace or an induction melting furnace to melt the weighed pure lead, and adjust the melt temperature to 750 - 1000 °C;

[0011] 2) Add the weighed silver and aluminum elements to the melt;

[0012] 3) Stir the alloy melt thoroughly and keep it warm for 20 - 30 min to form a homogeneous melt;

[0013] 4) Use casting or continuous solidification technology to cool and solidify the alloy melt to obtain a Pb - Ag - Al alloy material.

[0014] The principle of the present invention is as follows:

[0015] A small amount of Al element is added to the alloy of the present invention. After the addition of Al element, it mainly exists in the form of a shell / core - structured (Ag, Al) rich dispersed phase, where the shell layer of the dispersed phase is rich in Ag element and the core is rich in Al element. The addition of Al element improves the performance of the alloy through the following ways.

[0016] The lead - based alloy first undergoes the following reaction in sulfuric acid solution to form a passivation film, thereby preventing the matrix from further corrosion:

[0017]

[0018] Therefore, the integrity of the passivation film determines the corrosion resistance of the alloy. Al plays a pinning role on the oxide film, improving the density of the oxide film and the bonding force between the oxide film and the matrix. In addition, after the addition of Al, a dense alumina film has been formed, so it can significantly improve the corrosion resistance of the alloy. Therefore, the addition of Al can greatly enhance the corrosion resistance of the alloy.

[0019] Advantages and beneficial effects of the present invention:

[0020] The Pb - Ag - Al alloy material prepared by the present invention has excellent corrosion resistance. Compared with the Pb - 1Ag alloy widely used in industry, its corrosion rate in sulfuric acid solution is reduced by more than 54%. This material has great application prospects in the fields of hydrometallurgy and energy. Description of the drawings

[0021] Figure 1 is the microstructural morphology of the Pb - Ag - Al alloy prepared by the method of Example 1;

[0022] Figure 2 is the morphology and element distribution of the second phase in the Pb - Ag - Al alloy prepared by the method of Example 1;

[0023] Figure 3 is the microstructural morphology of the Pb - Ag - Al alloy prepared by the method of Example 2. Detailed implementation manners

[0024] In a specific implementation process, the present invention provides a highly corrosion-resistant Pb-Ag-Al alloy material, whose formula ratio is: 0.5-2.0% silver, 0.15-0.8% aluminum, and the balance is lead, by weight percentage. The alloy material structure consists of a Pb matrix and a second phase rich in (Ag, Al), and the size of the second phase is between several microns and tens of microns; the second phase rich in (Ag, Al) in the alloy material presents a shell / core structure, wherein the shell of the second phase is rich in Ag elements and the core is rich in Al elements; the corrosion rate of the alloy material in sulfuric acid solution is reduced by more than 54% compared with the Pb-1Ag alloy.

[0025] A method for preparing a highly corrosion-resistant Pb-Ag-Al alloy material comprises the following steps:

[0026] 1) Melt the weighed pure lead in a resistance furnace or induction melting furnace and adjust the melt temperature to 750~1000℃;

[0027] 2) adding weighed silver and aluminum elements to the melt;

[0028] 3) The alloy melt is fully stirred and kept warm for 20-30 minutes to form a uniform melt;

[0029] 4) The alloy melt is cooled and solidified by casting or continuous solidification technology to obtain the Pb-Ag-Al alloy material.

[0030] The specific implementation modes of the present invention are further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention but cannot be used to limit the scope of the present invention.

[0031] Example 1

[0032] In this embodiment, a highly corrosion-resistant Pb-Ag-Al alloy material is prepared by a method comprising the following steps:

[0033] 1) Weigh the lead, silver and aluminum raw materials according to the following weight percentages;

[0034] 2) Put the weighed lead into the crucible, heat it in a resistance furnace to melt it and raise the temperature to 750℃;

[0035] 3) Gradually add weighed silver raw materials into the lead melt;

[0036] 4) Gradually add weighed aluminum raw materials into the melt;

[0037] 5) After the added silver and aluminum are completely melted, keep the temperature for 20 minutes to ensure that the alloy melt is completely homogenized;

[0038] 6) The crucible containing the melt was pulled into the cooling medium at a pulling speed of 7 mm / s to cool and solidify, obtaining the Pb-Ag-Al alloy material;

[0039] Figure 1 The microstructure morphology of the Pb-Ag-Al alloy prepared by this example is given, and its composition is Pb-1 wt% Ag-0.15 wt% Al. It can be seen that the alloy is mainly composed of a Pb matrix and a second phase, and the size of the second phase is usually between several microns and dozens of microns. Figure 2 The morphology and element distribution of the second phase in the Pb-Ag-Al alloy prepared by this example are given. It can be seen that the second phase presents a shell / core structure, with the shell layer rich in Ag elements and the core rich in Al elements. The corrosion rate of this alloy material in a 150 g / L sulfuric acid solution is about 0.30 g / (h·m 2 ), which is about 54% lower than the corrosion rate of the Pb-1 wt% Ag alloy (about 0.66 g / (h·m 2 ).

[0040] Example 2

[0041] In this example, a highly corrosion-resistant Pb-Ag-Al alloy material, by weight percentage, has the following formulation ratio: silver 1%, aluminum 0.5%, and the balance is lead. Its preparation method includes the following steps:

[0042] 1) Weigh the lead, silver, and aluminum raw materials according to the following weight percentages:

[0043] 2) Put the weighed lead into the crucible and heat it to melt with a resistance furnace and raise the temperature to 950 °C;

[0044] 3) Gradually add the weighed silver raw material to the lead melt;

[0045] 4) Gradually add the weighed aluminum raw material to the melt;

[0046] 5) After the added silver and aluminum are completely melted, keep it warm for 30 minutes to ensure complete homogenization of the alloy melt;

[0047] 6) The crucible containing the melt was pulled into the cooling medium at a pulling speed of 7 mm / s to cool and solidify, obtaining the Pb-Ag-Al alloy material;

[0048] Figure 3Figure 1 shows the microstructure morphology of the Pb-Ag-Al alloy prepared in this example, with a composition of Pb-1wt%Ag-0.5wt%Al. It can be seen that the alloy is mainly composed of a Pb matrix and a second phase, and the size of the second phase is usually between several microns and dozens of microns. The morphology and element distribution of the second phase in the Pb-Ag-Al alloy prepared in this example show that the second phase exhibits a shell / core structure, with a shell rich in Ag elements and a core rich in Al elements. The corrosion rate of this alloy material in a 150 g / L sulfuric acid solution is approximately 0.24 g / (h·m 2 ), which is about 63% lower than the corrosion rate of the Pb-1wt%Ag alloy (approximately 0.66 g / (h·m 2 ).

[0049] Example 3

[0050] In this example, a highly corrosion-resistant Pb-Ag-Al alloy material, by weight percentage, has a formulation ratio of: silver 1.5%, aluminum 0.5%, and the balance is lead. Its preparation method includes the following steps:

[0051] 1) Weigh lead, silver, and aluminum raw materials according to the following weight percentages;

[0052] 2) Place the weighed lead into a crucible and heat it to melting and raise the temperature to 950 °C using a resistance furnace;

[0053] 3) Gradually add the weighed silver raw material to the lead melt;

[0054] 4) Gradually add the weighed aluminum raw material to the melt;

[0055] 5) After the added silver and aluminum are completely melted, hold for 30 minutes to ensure complete homogenization of the alloy melt;

[0056] 6) Pull the crucible containing the melt into a cooling medium at a pulling speed of 7 mm / s to cool and solidify to obtain the Pb-Ag-Al alloy material;

[0057] The corrosion rate of this alloy material in a 150 g / L sulfuric acid solution is approximately 0.16 g / (h·m 2 ), which is about 75% lower than the corrosion rate of the Pb-1wt%Ag alloy (approximately 0.66 g / (h·m 2 ).

[0058] Example 4

[0059] In this example, a highly corrosion-resistant Pb-Ag-Al alloy material, by weight percentage, has a formulation ratio of: silver 2%, aluminum 0.5%, and the balance is lead. Its preparation method includes the following steps:

[0060] 1) Weigh the lead, silver, and aluminum raw materials according to the following weight percentages;

[0061] 2) Put the weighed lead into a crucible and heat it to melt using an electric resistance furnace and raise the temperature to 950 °C;

[0062] 3) Gradually add the weighed silver raw material to the lead melt;

[0063] 4) Gradually add the weighed aluminum raw material to the melt;

[0064] 5) Keep warm for 30 minutes after the added silver and aluminum are completely melted to ensure complete homogenization of the alloy melt;

[0065] 6) Pour the alloy melt into a graphite mold to cool and solidify to obtain a Pb-Ag-Al alloy material;

[0066] The corrosion rate of this alloy material in a 150 g / L sulfuric acid solution is about 0.15 g / (h·m 2 ), which is about 77% lower than the corrosion rate of the Pb-1wt%Ag alloy (about 0.66 g / (h·m 2 ).

[0067] Example 5

[0068] In this example, a highly corrosion-resistant Pb-Ag-Al alloy material, by weight percentage, its formulation ratio is: silver 0.5%, aluminum 0.5%, and the balance is lead. Its preparation method includes the following steps:

[0069] 1) Weigh the lead, silver, and aluminum raw materials according to the following weight percentages;

[0070] 2) Put the weighed lead into a crucible and heat it to melt using an electric resistance furnace and raise the temperature to 950 °C;

[0071] 3) Gradually add the weighed silver raw material to the lead melt;

[0072] 4) Gradually add the weighed aluminum raw material to the melt;

[0073] 5) Keep warm for 30 minutes after the added silver and aluminum are completely melted to ensure complete homogenization of the alloy melt;

[0074] 6) Pull the crucible containing the melt into the cooling medium at a pulling speed of 7 mm / s to cool and solidify to obtain a Pb-Ag-Al alloy material;

[0075] The corrosion rate of this alloy material in a 150 g / L sulfuric acid solution is about 0.28 g / (h·m 2 ), which is about 57% lower than the corrosion rate of the Pb-1wt%Ag alloy (about 0.66 g / (h·m 2 ).

[0076] Example 6

[0077] In this example, a highly corrosion-resistant Pb-Ag-Al alloy material, by weight percentage, has the following formulation ratio: silver 1%, aluminum 0.8%, and the balance is lead. Its preparation method includes the following steps:

[0078] 1) Weigh the lead, silver, and aluminum raw materials according to the following weight percentages;

[0079] 2) Put the weighed lead into a crucible and heat it to melt using an electric resistance furnace and raise the temperature to 1000 °C;

[0080] 3) Gradually add the weighed silver raw material to the lead melt;

[0081] 4) Gradually add the weighed aluminum raw material to the melt;

[0082] 5) After the added silver and aluminum are completely melted, keep warm for 30 minutes to ensure complete homogenization of the alloy melt;

[0083] 6) Pull the crucible containing the melt into the cooling medium at a pulling speed of 10 mm / s to cool and solidify to obtain the Pb-Ag-Al alloy material;

[0084] The corrosion rate of this alloy material in a 150 g / L sulfuric acid solution is about 0.14 g / (h·m 2 ), which is about 78% lower than the corrosion rate of the Pb-1wt%Ag alloy (about 0.66 g / (h·m 2 ).

[0085] Comparative Example 1

[0086] In this comparative example, a Pb-Ag alloy material, by weight percentage, has the following formulation ratio: silver 1%, and the balance is lead. Its preparation method includes the following steps:

[0087] In this comparative example, a preparation method of a Pb-Ag alloy material is as follows:

[0088] 1) Weigh the lead and silver raw materials according to the following weight percentages;

[0089] 2) Put the weighed lead into a crucible and heat it to melt using an electric resistance furnace and raise the temperature to 950 °C;

[0090] 3) Gradually add the weighed silver raw material to the lead melt;

[0091] 4) After the added silver is completely melted, keep warm for 30 minutes to ensure complete homogenization of the alloy melt;

[0092] 5) Pull the crucible containing the melt into the cooling medium at a lifting speed of 7 mm / s to cool and solidify to obtain the Pb-Ag alloy material;

[0093] The corrosion rate of the alloy material in a 150 g / L sulfuric acid solution is approximately 0.66 g / (h·m 2 ).

Claims

1. A highly corrosion-resistant Pb-Ag-Al alloy material, characterized in that, Calculated by weight percentage, the formula ratio is: 1.5-2.0% silver, 0.15-0.8% aluminum, and the balance is lead. The alloy material structure consists of a Pb matrix and a (Ag, Al)-rich second phase. The (Ag, Al)-rich second phase in the alloy material presents a shell / core structure, wherein the shell layer of the second phase is Ag-rich elements and the core is Al-rich elements.

2. The high-corrosion-resistant Pb-Ag-Al alloy material according to claim 1, wherein The corrosion rate of the alloy material in sulfuric acid solution is reduced by more than 54% compared with the Pb-1Ag alloy.

3. A method for preparing the high corrosion-resistant Pb-Ag-Al alloy material according to claim 1, characterized in that, The following steps are involved: 1) Melt the weighed pure lead in a resistance furnace or induction melting furnace and adjust the melt temperature to 750~1000℃; 2) adding weighed silver and aluminum elements to the melt; 3) The alloy melt is fully stirred and kept warm for 20-30 minutes to form a uniform melt; 4) The alloy melt is cooled and solidified by casting or continuous solidification technology to obtain the Pb-Ag-Al alloy material.

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