CN104060140A - A high temperature resistant magnesium oxide alloy - Google Patents

Abstract

The invention discloses a high-temperature-resistant magnesium oxide alloy which comprises the following components in percentage by mass: y: 1-3%, Sn: 0.1-1.5%, and the balance of magnesium and inevitable impurities. The preparation method of the high-temperature resistant magnesium oxide alloy comprises the following steps: firstly, selecting pure Mg, pure Sn and Mg-Y intermediate alloy, then heating the pure Mg to 690-705 ℃ under the protection of atmosphere, adding the pure Sn and Mg-Y intermediate alloy, fully stirring and smelting, and finally preserving the heat at 715-730 ℃ for 15-25 minutes for casting and molding. According to the invention, proper amount of Y and Sn are added into the magnesium alloy, the compactness of an oxidation film can be enhanced, the impurity content in the alloy is limited, the influence of impurities on the high-temperature oxidation performance is avoided, the preparation process parameters of the magnesium alloy are strictly limited, and the alloy material obtained by pouring has uniform tissue and few defects.

Description

A high temperature resistant magnesium oxide alloy

technical field

The invention belongs to the technical field of magnesium alloys, and relates to an anti-oxidation magnesium alloy, in particular to a high-temperature resistant magnesium alloy.

Background technique

Magnesium alloy has excellent comprehensive properties and is widely used, but its melting point is low, and it is easy to oxidize or even burn under high temperature conditions, which seriously limits its application range.

There are various factors affecting the high temperature oxidation performance of magnesium alloys, mainly including:

1. The chemical composition of the material, such as the type and distribution uniformity of alloying elements, impurities and their degree of segregation;

2. The phase composition and structure of the alloy, such as the phase transition in the high temperature oxidation zone, the macro and micro structure defects of the alloy, etc.;

3. The properties of the oxide film, including the properties of the oxide film itself, such as the integrity and compactness of the oxide film, that is, the ratio of the oxide volume to the metal volume (PBR), the thermodynamic stability and physical properties of the oxide film; the relationship between the oxide film and the metal Interface compatibility, such as the epitaxial growth relationship between the oxide film and the metal, the geometry of the interface, the chemical properties of the interface (such as the segregation of impurities at the interface), the interface energy and the interface bonding strength between the oxide film and the substrate; the oxide film is compatible with the gas phase properties, such as whether it constitutes an autocatalytic reaction or a redox reaction.

Ordinary magnesium alloys either have problems in chemical composition, or the structure of the alloy is unreasonable, or the oxide film obtained by initial oxidation does not meet the requirements, cannot prevent subsequent oxidation, and does not have high-temperature oxidation resistance.

Contents of the invention

In view of this, the object of the present invention is to provide a magnesium alloy with excellent high temperature oxidation resistance.

To achieve the above object, the present invention provides the following technical solutions:

The high-temperature resistant magnesium oxide alloy is composed of the following components in terms of mass percentage: Y: 1-3%, Sn: 0.1-1.5%, and the rest are magnesium and unavoidable impurities.

As a preferred embodiment of the high temperature resistant magnesium oxide alloy of the present invention, the mass percentage of Y is 1.5-2.2%, and the mass percentage of Sn is 0.1-0.5%.

As another preference of the high temperature resistant magnesium oxide alloy of the present invention, the mass ratio of Y to Sn is 2:1-7:1.

As a further preference of the high-temperature resistant magnesium oxide alloy of the present invention, the total amount of inevitable impurities is ≤0.03%, wherein Fe≤0.002%, Cu≤0.001%, and Si≤0.005%.

The method for preparing the high temperature resistant magnesium oxide alloy comprises the following steps:

1), materials: take pure Mg, pure Sn and Mg-Y master alloy, wherein the mass percentage of Y in the Mg-Y master alloy is 25-30%;

2) Melting: under the protection of CO ₂ and SF ₆ atmosphere, first heat pure magnesium to 690-705°C, then add pure Sn and Mg-Y master alloy, fully stir and smelt to obtain magnesium alloy melt;

3), pouring: heat the magnesium alloy melt in step 2) at 715-730°C for 15-25 minutes, remove impurities, and cast into shape;

4), air cooling the ingot obtained in step 3).

The beneficial effects of the present invention are: the present invention adds appropriate amount of Y and Sn to the magnesium alloy, and _Y2O3 (PBR value 1.39) and _SnO2 (PBR value 1.32) obtained during _oxidation can significantly enhance the compactness of the oxide film, Overcome the loose and porous defects of MgO film (PBR value 0.89), and the compatibility of SnO ₂ , Y ₂ O ₃ and MgO is good, and the oxide film containing Y is closely combined with the magnesium alloy matrix, and the physical and chemical properties of the obtained oxide film are stable, which prevents further The effect of magnesium oxide alloy is very obvious. The invention further limits the content of impurities in the alloy, especially Cu, Fe and Si, which can not only avoid the influence of impurities on the high-temperature oxidation performance of the alloy, but also fully reduce the cost caused by the content of impurities. The invention strictly limits the process parameters such as magnesium alloy smelting and heat preservation temperature, and the alloy material obtained by pouring has uniform structure and few macro and micro defects, and further enhances the high-temperature oxidation resistance of the alloy.

Description of drawings

In order to make the purpose, technical scheme and beneficial effect of the present invention clearer, the present invention provides the following drawings for illustration:

Fig. 1 is the obtained magnesium alloy of embodiment 1 and pure magnesium, the oxidation weight gain curve figure of AZ31 magnesium alloy;

Fig. 2 is the cross-sectional scanning picture of the oxide layer after the magnesium alloy oxidation treatment of embodiment 1;

Fig. 3, Fig. 4 and Fig. 5 are scanning electron microscope energy spectrum diagrams of the cross-section of the magnesium alloy oxide layer in Example 1, respectively reflecting the distribution of Mg, Y, and Sn in the cross-section.

Detailed ways

The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

The following examples will disclose a new type of magnesium alloy, the chemical composition and ratio of which are as follows: Y: 1-3%, Sn: 0.1-1.5%, and the rest is magnesium and unavoidable impurities.

Further, the mass percentage of Y in the alloy is 1.5-2.2%, and the mass percentage of Sn is 0.1-0.5%.

Further, the mass ratio of Y to Sn in the alloy is 2:1-7:1.

Further, the total amount of unavoidable impurities in the alloy is ≤0.03%, wherein Fe≤0.002%, Cu≤0.001%, and Si≤0.005%.

Example 1:

The method for preparing high temperature resistant magnesium oxide alloy in this embodiment includes:

1), drawing materials: take a certain amount of pure Mg, pure Sn and Mg-Y master alloy, wherein the mass percentage of Y in the Mg-Y master alloy is 30%;

2) Melting: under the protection of CO ₂ and SF ₆ atmosphere, the pure magnesium is first heated to 700°C, then pure Sn and Mg-Y master alloy are added, fully stirred and smelted to obtain a magnesium alloy melt;

3), pouring: heat the magnesium alloy melt in step 2) at 720° C. for 20 minutes, remove impurities, pour it into a steel mold with a diameter of 80 mm, and cast it to obtain an ingot;

4), air cooling the ingot obtained in step 3).

After testing, the chemical composition and ratio of the magnesium alloy obtained in this example are as follows: the chemical composition and ratio are as follows: Y: 1.75%, Sn: 0.25%, Mg: 97.98%; the total amount of impurities is 0.02%, of which: Fe =0.001%, Cu=0.001%, Si=0.003%.

The magnesium alloy obtained in this example, pure magnesium, and AZ31 magnesium alloy were respectively heated to 600°C at a rate of 10°C/min in an environment with sufficient air supply, kept for 2 hours, and their oxidation weight gain curves were tested.

Fig. 1 is the magnesium alloy obtained in embodiment 1 and pure magnesium, the oxidation weight gain curve of AZ31 magnesium alloy; As can be seen from the figure, pure Mg, AZ31 alloy weight gain are all more serious in the high temperature oxidation process, and Mg-Y The oxidation weight gain of the -Sn alloy is not obvious, indicating that the magnesium alloy prepared in this example has good high temperature oxidation resistance.

Figure 2 is a cross-sectional scanning picture of the oxide layer obtained by the magnesium alloy obtained in this example after being kept at 500°C for 6 hours. It can be seen that there is no obvious delamination between the oxide layer and the substrate, which shows that the oxide layer is combined with the substrate. Good ability, not easy to fall off.

Figure 3, Figure 4, and Figure 5 are the cross-sectional scanning electron microscope energy spectrum diagrams of the magnesium alloy oxide layer after oxidation treatment in Figure 2. It can be seen from the figure that the content of Mg element in the outer surface layer gradually decreases, while Y element is enriched in the surface layer , which shows that after high temperature oxidation, the Y element is enriched in the surface layer to form a composite oxide layer of Y ₂ O ₃ and MgO. Since the PBR value of Y ₂ O ₃ is 1.39, which is greater than 1, it can form a dense oxide layer with MgO , thereby improving the high temperature oxidation resistance of the alloy and preventing further oxidation of the alloy.

Example 2:

The method for preparing high temperature resistant magnesium oxide alloy in this embodiment includes:

1), drawing materials: take a certain amount of pure Mg, pure Sn and Mg-Y master alloy, wherein the mass percentage of Y in the Mg-Y master alloy is 25%;

2) Melting: under the protection of CO ₂ and SF ₆ atmosphere, the pure magnesium is first heated to 705°C, then pure Sn and Mg-Y master alloy are added, fully stirred and smelted to obtain a magnesium alloy melt;

3), pouring: heat the magnesium alloy melt in step 2) at 715° C. for 25 minutes, remove impurities, pour it into a steel mold with a diameter of 80 mm, and cast it to obtain an ingot;

4), air cooling the ingot obtained in step 3).

After testing, the chemical composition and ratio of the magnesium alloy obtained in this example are as follows: the chemical composition and ratio are as follows: Y: 1.6%, Sn: 0.5%, Mg: 97.65%; the total amount of impurities is 0.25%, of which: Fe =0.001%, Cu=0.001%, Si=0.005%

Example 3:

The method for preparing high temperature resistant magnesium oxide alloy in this embodiment includes:

1), drawing materials: get a certain amount of pure Mg, pure Sn and Mg-Y master alloy, wherein the mass percentage of Y in the Mg-Y master alloy is 28%;

2) Melting: under the protection of CO ₂ and SF ₆ atmosphere, firstly heat pure magnesium to 690°C, then add pure Sn and Mg-Y master alloy, fully stir and smelt to obtain magnesium alloy melt;

3), pouring: heat the magnesium alloy melt in step 2) at 730° C. for 15 minutes, remove impurities, pour it into a steel mold with a diameter of 80 mm, and cast it to obtain an ingot;

4), air cooling the ingot obtained in step 3).

After testing, the chemical composition and proportion of the magnesium alloy obtained in this embodiment are as follows: the chemical composition and proportion are as follows: Y: 2.1%, Sn: 0.9%, Mg: 96.7%; total amount of impurities = 0.03%, wherein: Fe=0.002%, Cu=0.001%, Si=0.005%

Example 4:

The method for preparing high temperature resistant magnesium oxide alloy in this embodiment includes:

1), drawing materials: get a certain amount of pure Mg, pure Sn and Mg-Y master alloy, wherein the mass percentage of Y in the Mg-Y master alloy is 28%;

2) Melting: under the protection of CO ₂ and SF ₆ atmosphere, the pure magnesium is first heated to 695°C, then pure Sn and Mg-Y master alloy are added, fully stirred and smelted to obtain a magnesium alloy melt;

3), pouring: heat the magnesium alloy melt in step 2) at 725° C. for 20 minutes, remove impurities and pour it into a steel mold with a diameter of 80 mm to form an ingot;

4), air cooling the ingot obtained in step 3).

After testing, the chemical composition and ratio of the magnesium alloy obtained in this example are as follows: Y: 1%, Sn: 0.2%, Mg: 98.78%; total amount of impurities = 0.02%, wherein Fe = 0.002%, Cu = 0.001%, Si = 0.002%.

Example 5:

The method for preparing high temperature resistant magnesium oxide alloy in this embodiment includes:

1), drawing materials: take a certain amount of pure Mg, pure Sn and Mg-Y master alloy, wherein the mass percentage of Y in the Mg-Y master alloy is 27%;

2) Melting: under the protection of CO ₂ and SF ₆ atmosphere, the pure magnesium is first heated to 700°C, then pure Sn and Mg-Y master alloy are added, fully stirred and smelted to obtain a magnesium alloy melt;

3), pouring: heat the magnesium alloy melt in step 2) at 725° C. for 18 minutes, remove impurities, pour it into a steel mold with a diameter of 80 mm, and cast it to obtain an ingot;

4), air cooling the ingot obtained in step 3).

After testing, the chemical composition and proportion of the magnesium alloy obtained in this embodiment are as follows: its chemical composition and proportion are as follows: Y: 3%, Sn: 1.5%, Mg: 95.47, total amount of impurities = 0.03%, wherein Fe = 0.001%, Cu=0.001%, Si=0.004%.

The present invention adds appropriate amount of Y and Sn to the magnesium alloy, which can significantly enhance the compactness of the oxide film and effectively prevent the continuous oxidation of the magnesium alloy. The invention further limits the special content of impurities in the alloy to avoid the influence of impurities on the high-temperature oxidation performance of the alloy. The invention strictly limits the process parameters such as magnesium alloy smelting and heat preservation temperature, and the alloy material obtained by pouring has uniform structure and few macro and micro defects, and further enhances the high-temperature oxidation resistance of the alloy.

Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that it can be described in terms of form and Various changes may be made in the details without departing from the scope of the invention defined by the claims.

Claims (5)

1. A high temperature resistant magnesium oxide alloy, characterized in that the magnesium alloy is composed of the following components by mass percentage: Y: 1-3%, Sn: 0.1-1.5%, and the rest are magnesium and unavoidable impurities . 2. The high temperature resistant magnesium oxide alloy according to claim 1, characterized in that: the mass percentage of Y is 1.5-2.2%, and the mass percentage of Sn is 0.1-0.5%. 3. The high temperature resistant magnesium oxide alloy according to claim 1 or 2, characterized in that: the mass ratio of Y to Sn is 2:1-7:1. 4. The high temperature resistant magnesium oxide alloy according to claim 1 or 2, characterized in that: the total amount of inevitable impurities is ≤0.03%, wherein Fe≤0.002%, Cu≤0.001%, Si≤0.005%. 5. The method for preparing the high-temperature resistant magnesium oxide alloy as claimed in any one of claims 1-4, is characterized in that, comprising the following steps: 1), materials: take pure Mg, pure Sn and Mg-Y master alloy, wherein the mass percentage of Y in the Mg-Y master alloy is 25-30%; 2) Melting: Under the protection of CO ₂ and SF ₆ atmosphere, the pure magnesium is first heated to 690-705°C, then pure Sn and Mg-Y master alloy are added, fully stirred and smelted to obtain a magnesium alloy melt; 3), pouring: heat the magnesium alloy melt in step 2) at 715-730°C for 15-25 minutes, remove impurities, and cast into shape; 4), air cooling the ingot obtained in step 3).