Strontium-yttrium-oxygen refractory material, preparation method thereof, crucible product thereof and application of crucible product

Abstract

The invention discloses a strontium yttrium oxide refractory material which is characterized by comprising the following components: 23-26 wt.% of strontium element; %, 53 to 55 wt.% of yttrium element; and the content of the oxygen element is 18-20 wt.%. The invention also discloses a preparation method, a crucible product and application thereof. Compared with the prior art, the crucible can be used for vacuum induction melting, casting and directional solidification of titanium alloy and other high-activity metal materials. The content of impurity elements in the product can be effectively controlled, the energy consumption and the cost in the production process are reduced, and the vacuum induction melting efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the field of manufacturing strontium yttrium oxygen refractory materials, and specifically relates to a strontium yttrium oxygen refractory material, a preparation method thereof, a crucible product thereof, and uses thereof. Background Art

[0002] Titanium or other highly reactive titanium-containing alloys have extremely high chemical activity in a high-temperature molten state and can chemically react with most known refractory materials, such as Al 2 O 3 , high-purity graphite, BN, SiO 2 , etc.

[0003] However, Y 2 O 3 with relatively high chemical stability has poor thermal shock resistance and mechanical properties and is prone to falling off or cracking during the melting process and is not suitable for the vacuum induction melting process. CaO is extremely prone to a hydration reaction in the storage environment and collapses.

[0004] Perovskite refractory materials (CaZrO3, SiZrO3, BaZrO3, etc.) are not suitable for the melting, casting, and directional solidification preparation of high-titanium-content alloys.

[0005] The physical and chemical reactions between the alloy melt and the refractory material seriously contaminate the alloy melt, increase the content of impurity elements in the finished product, and deteriorate the mechanical and fatigue properties of titanium and titanium alloys.

[0006] In summary, there is currently a lack of a high-stability refractory material crucible for the vacuum induction melting preparation of pure titanium and titanium alloys. Summary of the Invention

[0007] In order to overcome the above-mentioned defects of the prior art, the purpose of the present invention is to provide a strontium yttrium oxygen refractory material, a preparation method thereof, a crucible product thereof, and uses thereof, which can be used as a high-stability refractory material crucible for the vacuum induction melting preparation of pure titanium or titanium alloys.

[0008] The high stability referred to in the present invention means high-temperature stability, and after the melting is completed, the thickness of the erosion layer is small, the surface of the crucible is clean, and there are no metal residues.

[0009] A strontium yttrium oxygen refractory material comprises the following components:

[0010] Strontium element 23-26 wt.%;

[0011] Yttrium element 53-55 wt.%;

[0012] Oxygen element is 18-20 wt.%.

[0013] A preparation method of a strontium yttrium oxygen refractory material comprises:

[0014] Step 1: Mix the powder containing strontium element, yttrium element, and oxygen element according to the molar ratio of Sr:Y:O = 1:1-3:3-5 to obtain a mixed powder; preferably 1:2:4.

[0015] Step 2: Mix the mixed powder, ball milling beads, and organic solvent according to the mass ratio of 3-4:4-5:0.8-1.2, and then put them into a ball mill to mill until the powder is uniform.

[0016] Step 3: Dry the uniform powder and then screen the dry powder.

[0017] Step 4: Transfer the sieved dry powder to an alumina crucible, place it in a high-temperature electric furnace, and calcine at a temperature of 1300 °C to 1400 °C to obtain SrYO powder through the reaction shown in Reaction Formula 1 below, and then repeat the ball milling in Step 2 to obtain high-purity SrYO powder.

[0018] SrCO(s) → SrO(s) + CO(g), SrO + YO → SrYO

[0019] Reaction Formula 1.

[0020] In a preferred embodiment of the present invention, Step 1 is to use SrCO powder and YO powder with a purity of 99.99% as raw materials, and mix SrCO and YO according to a molar ratio of 1:1.

[0021] In a preferred embodiment of the present invention, the organic solvent in Step 2 is anhydrous ethanol, and the ball milling beads are zirconia ball milling beads.

[0022] In a preferred embodiment of the present invention, the drying in Step 3 is to dry at 120 °C for 2-4 hours.

[0023] In a preferred embodiment of the present invention, the high-temperature calcination is carried out at 1350 °C for 24 hours.

[0024] In a preferred embodiment of the present invention, the purity of the high-purity SrYO powder is above 99%.

[0025] A crucible product of a strontium yttrium oxygen refractory material, which is obtained by subjecting the high-purity SrYO powder to a cold isostatic pressing combined with a high-temperature sintering process.

[0026] The cold isostatic pressing is to load the high-purity SrYO powder into a steel core rubber mold, put the mold filled with the powder into a cold isostatic press, and keep the pressure at 140-160 MPa for 5-10 minutes. Then take out the mold, complete the demolding, and obtain a crucible green body.

[0027] The high-temperature sintering is to load the crucible green body into a high-temperature sintering furnace, heat it at a heating rate of 100 °C / h to 1600 - 1720 °C, and keep it warm for 24 - 36 hours, and then cool it to room temperature in the furnace to obtain the crucible product of the strontium yttrium oxygen refractory material.

[0028] A use of a crucible product of a strontium yttrium oxygen refractory material, and the use is as a high-stability refractory material crucible for vacuum induction melting preparation of pure titanium or titanium alloys.

[0029] The beneficial effects of the present invention are as follows:

[0030] The crucible of the present invention can be used for vacuum induction melting, casting and directional solidification of titanium alloys and other high-reactivity metal materials. It can effectively control the content of impurity elements in the product, reduce the energy consumption and cost in the production process, and improve the efficiency of vacuum induction melting. Description of the Drawings

[0031] Figure 1 Is SrO-YO 1.5 Binary phase diagram (a).

[0032] Figure 2 Is TiO 2 , TiO, Y 2 O 3 , SrY 2 O 4 Schematic diagram of Gibbs free energy comparison (b).

[0033] Figure 3 Is the structure refinement diagram of the high-purity SrY 2 O 4 powder, and the SrY 2 O 4 crystal structure model diagram obtained by fitting.

[0034] Figure 4 Is using SrYO and Y 2 O 3 refractory material crucibles to melt titanium alloys respectively, cross-section and element distribution diagrams of the refractory materials: (a) is the cross-section diagram of the SrYO crucible, (b-d) are the element distributions of the SrYO crucible cross-section, and figure (e) is the Y 2 O 3 crucible cross-section diagram, (f-h) are the element distribution diagrams of the Y 2 O 3 crucible cross-section.

[0035] Figure 5 Is the comparison diagram of wetting test results,

[0036] where (a) is the wetting angle diagram of molten TiAl and SrYO;

[0037] (b) is molten TiAl and Y 2 O 3 Wetting angle diagram of refractory;

[0038] (c) is a top view of TiAl and SrYO after wetting;

[0039] (d) is TiAl and Y after wetting 2 O 3 top view;

[0040] (e) is a wetting surface diagram of SrYO refractory at the position in contact with TiAl alloy;

[0041] (f) is a wetting surface diagram of Y2O3 refractory at the position in contact with TiAl alloy.

[0042] Figure 6 is the result comparison diagram of Y 2 O 3 and SrYO refractory ceramic sheets,

[0043] wherein, (a) is the SEM morphology diagram of Y 2 O 3 refractory ceramic sheet

[0044] (b) is the enlarged image of the local position in a;

[0045] (c) is the element distribution diagram of Y 2 O 3 refractory ceramic sheet;

[0046] (d) is the EDS surface scan diagram of Al element;

[0047] (e) is the EDS surface scan diagram of Y element;

[0048] (f) is the SEM morphology diagram of SrYO ceramic sheet after wetting;

[0049] (g) is the local enlarged view of f;

[0050] (h) is the element distribution diagram of SrYO ceramic sheet after wetting;

[0051] (i) is the EDS surface scan diagram of Al element;

[0052] (j) is the EDS surface scan diagram of Y element.

[0053] Figure 7 is the bottom comparison diagram of titanium alloy in contact with SrYO and Y 2 O 3 after the wetting test,

[0054] wherein (a) is after the wetting test with Y2 O 3 SEM morphology diagram of the titanium alloy bottom in contact with the refractory ceramic sheet;

[0055] (b) is the enlarged view of the local area in (a);

[0056] (c) is Y 2 O 3 Element distribution map of the surface of the alloy bottom in contact with the refractory;

[0057] (d) is the EDS surface scan map of Al element;

[0058] (e) is the EDS surface scan map of Y element;

[0059] (f) is the SEM morphology diagram of the alloy bottom in contact with the SrYO refractory ceramic sheet after the wetting test;

[0060] (g) is the enlarged view of the local position in (f);

[0061] (h) is the element distribution map of the surface of the titanium alloy bottom in contact with the SrYO refractory;

[0062] (i) is the EDS surface scan map of Al element;

[0063] (j) is the EDS surface scan map of Y element.

[0064] Figure 8 Schematic diagram of the crucible mold. Specific implementation manners

[0065] To make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. However, it should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the scope of the present invention. In addition, in the following structures, the descriptions of well-known structures and technologies are omitted to avoid unnecessarily confusing the concepts of the present invention.

[0066] The inventors of the present invention unexpectedly found on the basis of thermodynamic calculations as shown in Figure 1 、 2 :

[0067] SrYO has an extremely high melting point and thermodynamic stability even lower than Y 2 O 3 . The crystal structure of SrYO is as shown in Figure 3 , SrYO belongs to the orthorhombic system, the space group belongs to P n m a, and its unit cell parameters are α = β = γ = 90°.

[0068] Subsequently, SrYO powder was prepared by high-temperature solid-phase sintering, and the crucible was prepared by using the cold isostatic pressing combined with high-temperature sintering process of the present invention.

[0069] The vacuum induction melting experiment of titanium alloy was carried out by using this crucible, and it was found that the crucible of the present invention can be used as a crucible of high-stability refractory material for the vacuum induction melting preparation of pure titanium or titanium alloy.

[0070] The following is a specific description in combination with examples, data and figures:

[0071] Example 1:

[0072] The present invention provides a preparation method of strontium yttrium oxygen refractory material, which includes the following steps:

[0073] Ingredient preparation: In the raw material mixture, strontium element, yttrium element and oxygen element are mixed according to the molar ratio of Sr:Y:O = 1:2:4. Specifically, SrCO powder and YO powder with a purity of 99.99% are used as raw materials and mixed according to the molar ratio of 1:1.

[0074] Ball milling: An appropriate amount of absolute ethanol is added to the raw material mixture, and then it is transferred to the ball milling tank of the ball mill, and zirconia balls are added to the ball milling tank. The mass ratio of the powder, ball milling beads and absolute ethanol is 3 - 4:4 - 5:0.8 - 1.2. Subsequently, ball milling is carried out for 6 - 10 hours to obtain uniform powder.

[0075] Drying: The ball-milled powder is placed in a drying oven and dried at 120°C for 2 - 4 hours, and then the dry powder is screened to obtain dry powder.

[0076] Calcination synthesis: The dried powder is transferred to an alumina crucible and placed in a high-temperature electric furnace, and calcined at 1350°C for 24 hours. The reactions SrCO(s) → SrO(s) + CO(g), SrO + YO → SrYO occur to synthesize SrYO powder.

[0077] Secondary ball milling: The synthesized SrYO powder is subjected to an additional 10-hour ball milling treatment to obtain SrYO powder with a purity of over 99%.

[0078] Loading: The SrYO powder with a purity of over 99% is loaded into the inside of a steel-core rubber mold, and the mold structure is as Figure 8 shown.

[0079] Cold isostatic pressing: The mold filled with the powder is placed in a cold isostatic press and kept at a pressure of 140 - 160 MPa for 5 - 10 min. Subsequently, the mold is taken out and demolded to obtain a green crucible body.

[0080] High-temperature sintering: Load the green compact into a high-temperature sintering furnace, heat it at a heating rate of 100 °C / h to 1600 - 1720 °C, and hold for 24 - 36 hours. Then cool it in the furnace to room temperature to obtain the finished SrY oxygen refractory material crucible.

[0081] Example 2:

[0082] The present invention provides a vacuum induction melting process for preparing titanium alloy using the SrY 2 O 4 crucible described in Example 1:

[0083] Crucible installation: Fix the SrY 2 O 4 crucible inside the vacuum induction furnace coil using MgO powder, and apply a layer of water glass on the top of the furnace lining to maintain stability;

[0084] Charging: Load a sample with an alloy composition of Ti - 46Al - 8Nb wt. % into the crucible, and use a mechanical pump + diffusion pump to pump the pressure inside the furnace to below 1×10 -2 Pa;

[0085] Melting: Increase the power of the vacuum induction furnace to 40 - 60 kW to raise the alloy temperature to 1600 - 1750 °C.

[0086] Refining: Hold the melted alloy at 1600 - 1750 °C for 3 - 10 min to ensure full homogenization of the chemical composition of the alloy.

[0087] Casting: Pour the alloy melt into a mold and cool it to room temperature.

[0088] Using the same process and a Y 2 O 3 crucible to prepare titanium alloy and comparing the melting results.

[0089] The impurity content of the titanium alloy prepared using the two crucibles was tested using a nitrogen oxide analyzer as shown in Table 1.

[0090] Table 1 shows the impurity element content in the titanium alloy after melting using different crucibles

[0091]

[0092] Combined with Table 1, it can be seen that the impurity element content in the titanium alloy melted using the SrY 2 O 4 crucible of the present invention is significantly reduced. Using a scanning electron microscope and energy spectrum analysis, the reaction interface between the melt and the crucible was observed as Figure 4 shown.

[0093] The results show that:

[0094] The strontium yttrium oxide refractory crucible of the present invention shows superiority over Y 2 O 3 The crucible has high temperature stability, and after smelting, the corrosion layer thickness is small, the crucible surface is clean and there is no metal residue.

[0095] This shows that the present invention can be used for the vacuum induction melting preparation of titanium alloy products, and the impurity content of the smelted titanium alloy is lower than that of the same process using Y 2 O 3 Titanium alloy products prepared in crucible.

[0096] Embodiment three:

[0097] The titanium alloy melt wetting experiment was carried out using the strontium yttrium oxide refractory material of Example 1 of the present invention:

[0098] Ceramic sheet pressing: The SrYO powder prepared in the above Example 1 was pressed into a circular sheet with a diameter of 1.5 cm and a thickness of 0.5 cm using a powder tablet press at 14 MPa;

[0099] High temperature sintering: the round slices after pressing are sintered at 1600-1700℃ for 24 hours and then cooled to room temperature in the furnace;

[0100] Wetting experiment: 5mm 3 The titanium alloy block is placed on a ceramic sheet and both are placed in a vacuum induction furnace. The power is increased to completely melt the metal and the temperature is controlled at 1650°C for 5 minutes. It is then cooled to room temperature. After the molten alloy cools on the ceramic sheet to form hemispherical droplets, the alloy and the shell are taken out for further analysis. 2 O 3 The wetting experiment of ceramic sheets was carried out under the same conditions.

[0101] Subsequently, SrYO and Y 2 O 3 The wetting test results were compared with those of

[0102] The strontium yttrium oxide refractory material proposed by the present invention is 2 O 3 Shows a larger wetting angle (such as Figure 5 ), the surface of the ceramic sheet is more complete (such as Figure 6 ), less refractory material remains on the metal surface (such as Figure 7 ), indicating that the strontium yttrium oxide refractory material of the present invention is better than Y 2 O 3 It has lower wettability to titanium alloy melt and is more suitable for casting and directional solidification of titanium alloy.

[0103] The above has shown and described the basic principles, main features and advantages of the invention.

[0104] Those skilled in the art should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification only illustrates the principle of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of the present invention claimed is defined by the appended claims and their equivalents.

Claims

1. A strontium-yttrium oxide refractory material, characterized in that: The components include: Strontium 23-26wt.%; Yttrium element 53-55wt.%; The oxygen element is 18-20wt.%.

2. The method for preparing a strontium yttrium oxide refractory material according to claim 1, characterized in that: include: Step 1: mixing powders containing strontium, yttrium and oxygen in a molar ratio of Sr:Y:O=1:1-3:3-5 to obtain a mixed material; Step 2, mixing the mixed powder with ball milling beads and organic solvent in a mass ratio of 3-4:4-5:0.8-1.2 and then putting the mixed powder into a ball mill for ball milling until the powder is uniform; Step 3, drying the uniform powder and then sieving the dry powder; Step 4: transfer the sieved dry powder to an alumina crucible, place it in a high-temperature electric furnace, and calcine it at a temperature of 1300 to 1400 degrees Celsius to obtain SrYO powder through the reaction shown in the following reaction formula 1, and then repeat the ball milling in step 2 to obtain high-purity SrYO powder; SrCO(s)→SrO(s)+CO(g), SrO+YO→SrYO Reaction formula 1.

3. The method for preparing a strontium yttrium oxide refractory material according to claim 2, characterized in that: The step 1 is to use SrCO powder and YO powder with a purity of 99.99% as raw materials, and mix SrCO and YO in a molar ratio of 1:1; The organic solvent in step 2 is anhydrous ethanol, and the ball milling beads are zirconium oxide ball milling beads; The drying in step 3 is performed at 120 degrees Celsius for 2-4 hours; The high temperature calcination is calcination at 1350 degrees Celsius for 24 hours.

4. The method for preparing a strontium yttrium oxide refractory material according to claim 2, characterized in that: The purity of the high-purity SrYO powder is above 99%.

5. A crucible product of a strontium yttrium oxide refractory material, wherein the crucible product is prepared by cold isostatic pressing and high temperature sintering of the high purity SrYO powder according to any one of claims 2 to 4; The cold isostatic pressing is to fill the high-purity SrYO powder into a steel core rubber mold, put the mold filled with powder into a cold isostatic press, and maintain the pressure at 140-160MPa for 5-10 minutes. Then, the mold is taken out and demoulding is completed to obtain a crucible blank; The high temperature sintering is to load the crucible blank into a high temperature sintering furnace, heat it to 1600-1720°C at a heating rate of 100°C / h, and keep it warm for 24-36 hours, then cool the furnace to room temperature to obtain the crucible product of the strontium yttrium oxide refractory material.

6. Use of the crucible product of the strontium yttrium oxide refractory material as claimed in claim 5, wherein the crucible product is used as a high-stability refractory crucible for vacuum induction melting of pure titanium or titanium alloy.

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