Preparation method and application of homogeneous titanium-palladium alloy

Abstract

The invention discloses a preparation method and application of a homogeneous titanium-palladium alloy, and the preparation method comprises the following steps: putting sponge titanium and palladium-gold fragments into a vacuum induction melting furnace in melt quenching equipment according to the mass ratio of (96-98): (4-2) for rapid smelting, and then quenching into a titanium-palladium intermediate alloy with the thickness of 40-60 microns and the width of 5-10 mm under the protection of argon; crushing the titanium-palladium intermediate alloy into titanium-palladium intermediate alloy fragments with the same particle size as the sponge titanium; the method comprises the following steps: weighing sponge titanium and titanium-palladium intermediate alloy fragments according to a mass ratio of (8-9): (2-1), and physically and uniformly mixing; pressing the mixture into a blank block, namely the titanium-palladium electrode; smelting the titanium-palladium electrode in a vacuum consumable electrode furnace for multiple times to obtain a titanium-palladium alloy ingot; and carrying out homogenizing annealing treatment on the titanium-palladium alloy ingot in a vacuum annealing furnace to obtain the titanium-palladium alloy. According to the method, the content and uniformity of the Pd element in the Ti-Pd alloy can be accurately controlled, and the homogeneous titanium-palladium alloy free of segregation and inclusion metallurgical defects is prepared.

Description

Technical Field

[0001] The invention belongs to the technical field of metal materials and relates to a preparation method of a homogeneous titanium-palladium alloy and application thereof. Background Art

[0002] Titanium alloys, formed by adding other alloying elements to the titanium base, exhibit high strength and corrosion resistance, making them a corrosion-resistant structural material. Technological advancements have placed higher demands on the performance of titanium alloy castings, as well as the uniformity of their composition. Titanium-palladium alloy Ti-0.2Pd, an α-titanium alloy, not only retains the processing and mechanical properties of industrial pure titanium, and exhibits excellent corrosion resistance in oxidizing media, but also offers resistance to localized and crevice corrosion in thermally reducing acidic media, chlorine-saturated brine, moist halogens, and acidic chlorides. Therefore, titanium-palladium alloys, due to their strong corrosion resistance, particularly crevice corrosion resistance, are widely used in the petroleum, chemical, and medical fields. The Pd content of Ti-0.2Pd alloys is typically 0.1-0.2% by weight. This low Pd content makes it difficult to control the uniformity of the palladium distribution within the alloy, severely impacting its corrosion resistance.

[0003] Chinese Patent Publication No. CN102051493A prepares a uniform multi-component titanium alloy by selecting alloying elements and / or master alloys based on the composition of the alloy. The alloying elements and / or master alloys are then uniformly mixed and spaced apart with titanium sponge layers to form consumable electrodes in 5-9 layers. The prepared electrodes are then melted three times in a vacuum consumable electrode furnace and then cooled to produce the titanium alloy. During the fabrication process, the combined weight of the first and last titanium sponge layers accounts for two-thirds of the total titanium sponge weight. Chinese Patent Publication No. CN101481759A prepares a corrosion-resistant titanium alloy containing ruthenium (ruthenium content 0.11% by weight). Ruthenium powder and titanium sponge are uniformly mixed and pressed into electrode blocks. The blocks are then plasma arc welded to form larger electrodes, which are then vacuum arc melted at least twice to form titanium alloy ingots. The Chinese patent with publication number CN107297485A uses a detachable auxiliary bracket to divide the mold cavity into N horizontally arranged (N≥16) grids when preparing a large ingot of titanium alloy containing trace elements. Sponge titanium and intermediate alloy are used as raw materials, and the materials are weighed and proportioned according to the nominal composition of the titanium alloy to be prepared to obtain N portions of mixed raw materials, and N portions of trace element powder are prepared. Half of each portion of the mixed raw materials is poured into its corresponding grid, and each portion of trace element powder is poured into its corresponding grid. Then, the remaining half of each portion of the mixed raw materials is poured into its corresponding grid and the auxiliary bracket is removed from the mold cavity. Subsequently, a short-stroke vertical pressing is used to press the mixed raw materials in the mold cavity into a large single-weight electrode block at one time, and then multiple large single-weight electrode blocks are welded into consumable electrodes, and the consumable electrodes are subjected to 2-3 vacuum consumable smelting to obtain a large ingot of titanium alloy containing trace elements. In the paper "Preparation Technology and Evaluation Method of High-Uniformity Titanium Alloy Ingots" published in "Casting Engineering", Han Yunfei et al. used high-grade raw materials, adjusted the alloy formula, accurately weighed, controlled the composition fluctuations of the main chemical elements Al, Zr, Mo and V, mixed the materials evenly, avoided foreign matter contamination, summarized the melting experience parameters such as current, voltage and vacuum degree, optimized the operating methods, and used vacuum consumable electrode melting technology to prepare titanium alloy ingots with small chemical composition fluctuations and uniformity.

[0004] It can be seen that it is indeed difficult to control the uniformity of component distribution in the preparation of both binary and multi-component titanium alloy castings. Although various methods such as powder mixing, consumable electrode method, and vacuum melting are available, it is still difficult to solve the problem of uniform composition. To this end, the present invention uses special methods to obtain an intermediate alloy with a high content of trace components and a morphology similar to the raw material sponge titanium, thereby ensuring the accuracy and uniformity of the addition of the trace component palladium element in the final titanium-palladium alloy. Summary of the Invention

[0005] In order to solve the above problems, the present invention provides a method for preparing a homogeneous titanium-palladium alloy, which can accurately control the content and uniformity of the Pd element in the Ti-Pd alloy, and prepare a homogeneous titanium-palladium alloy without segregation and inclusion metallurgical defects.

[0006] Another object of the present invention is to provide a method for preparing a homogeneous titanium-palladium alloy and to apply the homogeneous titanium-palladium alloy obtained by the method in the fields of medical care, health care and petrochemical industry.

[0007] The technical solution adopted by the present invention is a method for preparing a homogeneous titanium-palladium alloy, characterized in that it comprises the following steps:

[0008] Step 1: Prepare raw materials: titanium sponge with a particle size of 100-200 mesh and palladium gold fragments with a particle size of 100-200 mesh.

[0009] Step 2, preparation of titanium-palladium intermediate alloy strip: Sponge titanium and palladium gold fragments are placed in a vacuum induction melting furnace in a melt quenching device in a mass ratio of 96-98:4-2, and quickly (3-10 minutes) melted to prevent the formation of Ti2Pd or TiPd3 phases with different atomic ratios, accompanied by magnetic stirring (3-10 minutes), waiting for 3-10 minutes after melting, and then filled with argon. Under argon protection (argon pressure 0.1-0.5MPa), it is rapidly cooled into a titanium-palladium intermediate alloy with a thickness of 40-60 microns and a width of 5-10mm; the thin strip of titanium-palladium intermediate alloy is rapidly solidified under strong stirring, and there is no time for precipitation and segregation, which can ensure the uniformity of titanium and palladium composition. On the other hand, it is easy to break and will not introduce other impurities in the subsequent crushing or pressing process, thereby ensuring the purity of the overall alloy.

[0010] Step 3, fragmentation treatment of the titanium-palladium master alloy: crushing the titanium-palladium master alloy prepared in step 2 into titanium-palladium master alloy fragments having the same particle size as that of sponge titanium.

[0011] Step 4: Mixing titanium sponge and titanium-palladium master alloy: Weigh titanium sponge and titanium-palladium master alloy fragments in a mass ratio of 8-9:2-1, and physically mix them evenly;

[0012] Step 5: Cold pressing of titanium-palladium electrode blocks: The mixture from step 4 is placed into a steel cold pressing mold of fixed size and pressed into a block, i.e., a titanium-palladium electrode, at a pressing pressure of 600-800 MPa; the pressing is not maintained or maintained for 3-10 seconds;

[0013] Step 6. Preparation of titanium-palladium alloy ingot: Titanium-palladium electrodes are repeatedly smelted in the vacuum consumable electrode area to obtain titanium-palladium alloy ingots; that is, they are melted little by little while solidifying little by little to ensure that the material composition distributed more evenly in the previously formed electrode does not segregate; the density of titanium and palladium is quite different. If they are simply mixed and pressed into shape, and then the electrode is remelted, the unmelted part will expand under the action of the surrounding high temperature, causing the palladium mixed in the titanium to flow (the palladium will drift in the liquid phase), thereby affecting the uniformity.

[0014] Step 7: Homogenization Annealing: The titanium-palladium alloy ingot is homogenized and annealed in a vacuum annealing furnace. This homogenization annealing utilizes interatomic diffusion to further homogenize the two components and eliminate dendrites, minor segregation, and lattice distortion formed during the remelting process.

[0015] Furthermore, in the step 1, the titanium sponge is commercially available grade 0 titanium sponge, and the purity of the palladium gold fragments is ≥99%.

[0016] Furthermore, in the step 2, the vacuum degree of the vacuum induction melting furnace is 9×10 -3 Pa~6×10 -4 Pa, the current of the vacuum induction melting furnace is 20~40A.

[0017] Furthermore, in the step 2, the rapid cooling is achieved by a water-cooled copper roller at 2000 to 5000 rpm.

[0018] Furthermore, in the step 4, the physical mixing is carried out in a blade mixer with titanium sputtered on the surface, the blade speed is 200 to 500 rpm, and the mixing time is 30 to 60 minutes.

[0019] Furthermore, in step 4, after physical mixing, the mixture is randomly sampled and its uniformity is observed under a microscope, or a sampling circle is randomly determined for the mixture, and then the mass of the particles in the sampling circle is weighed and the number of particles in the circle is counted, and the deviation is calculated by the following formula:

[0020]

[0021] Where: M x With m xThey are the total number of particles contained in the sampling circle with a radius of R and the total mass of the corresponding particles, respectively. r is the radius of the mixed material particles, that is, the particle radius of the sponge titanium; C'0 is a constant, ranging from 1 to 3; δ represents the deviation number. When the calculated deviation number δ is not greater than 5%, the mixing has achieved the required uniformity. This step performs a uniformity check in the intermediate process to ensure the uniformity of the mixture of the intermediate alloy and the sponge titanium, and further improve the uniformity of the distribution of the titanium-palladium alloy obtained by the subsequent electrode remelting. If the calculated deviation number δ is greater than 5%, continue mixing in the blade mixer at a speed of 100-300 rpm for 60 to 120 minutes, but generally not more than 3 hours.

[0022] Furthermore, in step 5, the density of the titanium palladium electrode is 4.0-4.3 g / cm 3 .

[0023] Furthermore, in step six, arc melting is carried out in a vacuum consumable electrode furnace with a vacuum degree of 1Pa to 0.01Pa, an arc starting current of 1 to 2kA, a melting current of 2 to 3kA, and a voltage of 20 to 25V; the axial movement speed of the consumable electrode is controlled at 10 to 20 mm / min to achieve gradient zone melting.

[0024] Furthermore, in step seven, the titanium-palladium alloy ingot is kept in a vacuum annealing furnace at a temperature of 550-600°C for 6-10 hours, with a vacuum degree of 10 -1 ~10 -3 Pa, followed by furnace cooling, is obtained. The homogenization annealing temperature of 550-600°C is selected based on the Ti-Pd phase diagram to ensure that the final product is equiaxed α titanium. If it exceeds 600°C, β titanium will be formed. If it is lower than 550°C, the homogenization annealing effect will not be achieved, and the atomic diffusion is too slow to eliminate the dendrites formed by the melt casting.

[0025] The homogeneous titanium-palladium alloy prepared by the above-mentioned preparation method is used in the fields of medical care, health care and petrochemical industry.

[0026] The beneficial effects of the present invention are:

[0027] The present invention achieves highly homogenized composition by synergistically mixing prefabricated titanium-palladium master alloy fragments with titanium sponge. The titanium-palladium master alloy is prepared by uniformly mixing titanium sponge and palladium gold fragments and then rapidly cooling the melt (spinning). Vigorous stirring in the liquid state allows the mutual dissolution or reaction of Ti and Pd. The titanium-palladium master alloy strip prepared in this way has a uniform composition and is easy to control in thickness and width. The alloy strip can also be easily broken into fragments of similar shape and size to the titanium sponge. When the titanium sponge and master alloy are pressed and mixed in the next step, they are easily mixed evenly, without requiring special treatment of the master alloy sheets. Element segregation can be suppressed, resulting in a master alloy with uniform composition. Fragments matching the particle size of the titanium sponge can then be produced through mechanical crushing.

[0028] The present invention mixes the master alloy fragments with titanium sponge at a high speed according to the mass ratio, and utilizes the similar morphological characteristics of the two to achieve three-dimensional uniform dispersion. Since the amount of titanium-palladium master alloy added is greater than the amount of palladium powder added and the shape and size of the master alloy are similar to those of titanium sponge, the pressed electrode composition is more uniform; after high-pressure cold pressing, the obtained density is 4.0-4.3g / cm 3 The composite electrode block has a significantly better composition distribution uniformity than the traditional palladium powder direct mixing process; multiple gradient smelting processes are carried out in a vacuum consumable electrode furnace. Such successive remelting can not only eliminate metallurgical defects, but also help to purify the alloy. Vacuum annealing is then performed to achieve atomic-scale diffusion homogenization, ultimately obtaining high-quality titanium-palladium alloy ingots with no segregation and low impurities. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0030] Figure 1 It is a schematic diagram of preparing titanium-palladium intermediate alloy thin strip by rapid cooling of melt in an embodiment of the present invention.

[0031] Figure 2 This is a schematic diagram of a physical mixing device for titanium sponge and master alloy fragments according to an embodiment of the present invention.

[0032] Figure 3 Schematic diagram of sampling of the mixture according to the embodiment of the present invention.

[0033] Figure 4a 3 is a scanning electron microscope photograph of the titanium-palladium alloy prepared in Example 1 of the present invention.

[0034] Figure 4b yes Figure 4a The distribution of alloying element Ti in the steel.

[0035] Figure 4c yes Figure 4a Distribution of alloying element Pd in ​​the steel.

[0036] Figure 5 This is the metallographic structure of the equiaxed grain TiPd alloy obtained in Example 1 of the present invention.

[0037] Figure 6 This is the macroscopic morphology of the titanium-palladium master alloy prepared by rapid quenching of the melt in Example 1 of the present invention.

[0038] Figure 7The morphology of the TiPd alloy powder is similar to that of sponge titanium by the melt rapid quenching method in Example 1 of the present invention.

[0039] Figure 8 This is the metallographic structure of the titanium-palladium alloy prepared in Example 2 of the present invention.

[0040] Figure 9 This is the microstructure of the titanium-palladium alloy prepared in Example 3 of the present invention.

[0041] Figure 10a This is the microstructure of the titanium-palladium alloy prepared in Comparative Example 1.

[0042] Figure 10b This is the microstructure of the titanium-palladium alloy prepared in Comparative Example 2.

[0043] Figure 10c This is the microstructure of the titanium-palladium alloy prepared in Comparative Example 3.

[0044] In the figure, 1. base, 2. support legs, 3. mixing box, 4. hopper, 5. side plate, 6. discharge port, 7. sleeve box, 8. pull rod, 9. blade, 10. rubber sheet, 11. spring, 12. reinforcing rod; 13. quartz tube, 14. molten metal, 15. heater coil, 16. molten metal jet, 17. thin strip, 18. water-cooled copper roller. DETAILED DESCRIPTION

[0045] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0046] Example 1,

[0047] A method for preparing a homogeneous titanium-palladium alloy comprises the following steps:

[0048] Step 1: Prepare the raw materials: Use commercially available titanium sponge (grade 0) and palladium flakes (150 mesh particle size, purity ≥ 99%). Grade 0 titanium sponge is primarily for its high purity (99.7% to 99.8%) and low impurity content, which prevents the subsequent addition of small amounts of palladium from being affected by these impurities (forming compounds with or dissolving the palladium); the titanium sponge particle size is 150 mesh.

[0049] Step 2: Preparation of titanium-palladium master alloy strip: Weigh titanium sponge and palladium gold in a mass ratio of 98:2 and place them in a vacuum chamber with a degree of 1×10 -3Pa melt rapid melting in a vacuum induction melting furnace with a current of 30A, accompanied by magnetic stirring for 5 minutes; wait for 5 minutes after melting, then fill with argon, and under argon protection (argon pressure 0.1MPa), use a 3000 rpm water-cooled copper roller 18 to rapidly cool into a titanium-palladium intermediate alloy strip with a thickness of 50 microns and a width of 8mm; the titanium-palladium intermediate alloy strip solidifies rapidly under strong stirring, and there is no time for precipitation and segregation; on the other hand, it is easy to crush, and other impurities will not be introduced in the subsequent crushing or pressing process, thereby ensuring the purity of the overall alloy.

[0050] Step 3: Fragmentation of the titanium-palladium master alloy: The titanium-palladium master alloy prepared in step 2 is crushed into titanium-palladium master alloy fragments (chips) using a crusher. The crusher shell is made of titanium alloy, and the blades are made of hardened wear-resistant 9SiCr steel with a surface sputtered with TiN. This not only achieves high strength and wear resistance, but also prevents other impurities from mixing into the titanium-palladium master alloy. The size of the titanium-palladium master alloy fragments is the same as the particle size of sponge titanium.

[0051] Step 4: Mixing titanium sponge and titanium palladium master alloy: Weigh titanium sponge and titanium palladium master alloy sheets in a mass ratio of 9:1, and mix them in a blade mixer at a speed of 300 rpm for 40 minutes. Figure 3 Sampling is done in the manner shown. For the mixture, a random sampling circle is determined. The mass of the particles in the sampling circle is then weighed, and the number of particles in the circle is counted. The deviation is calculated using the following formula:

[0052]

[0053] Where: M x With m x They are the total number of particles contained in the sampling circle with a radius of R and the total mass of the corresponding particles, r is the radius of the mixed material particles (the particle radius of sponge titanium), C'0 is a constant, which is 1 to 3 here; δ represents the deviation number. When the calculated deviation number δ is not greater than 5%, the mixing has achieved the required uniformity.

[0054] Step 5: Cold pressing of titanium-palladium electrode blocks: The mixture from step 4 is loaded into a steel cold pressing mold of fixed size (the mold size can be adjusted arbitrarily according to production needs, and the loading amount is the product of the mold cavity volume and the density of titanium). The mixture is pressed under a pressing pressure of 700 MPa for 3 seconds to form a block with a certain strength (guaranteed by the density) and a certain shape (guaranteed by the mold), i.e., a titanium-palladium electrode with a density of 4.2 g / cm 3 .

[0055] Step 6. Preparation of titanium-palladium alloy ingot: The titanium-palladium electrode obtained in step 5 is placed in a vacuum consumable electrode furnace (vacuum degree is 1 Pa) and smelted twice with a process gradient of arcing current of 1.5 kA, melting current of 2.5 kA, and voltage of 22 V (the size of the ingot obtained by the first smelting is the same as the electrode size in step 5, and the size of the ingot obtained by the second smelting can be set according to user needs) to obtain a titanium-palladium alloy ingot; the axial movement speed of the consumable electrode is 10 mm / min.

[0056] Step 7: Homogenization annealing treatment: The titanium-palladium alloy ingot obtained in step 6 is kept in a vacuum annealing furnace at a temperature of 580°C for 8 hours with a vacuum degree of 10 -2 Pa, and then furnace cooling (put it in the furnace, turn off the power and cool it naturally under the same vacuum degree) to obtain a titanium palladium alloy ingot (equiaxed grain TiPd alloy) with uniform organization and composition.

[0057] The microstructure and element distribution of the titanium-palladium alloy prepared in Example 1 are as follows: Figures 4a-4c As shown, the distribution is very uniform. Figure 5 The metallographic structure of the equiaxed grain TiPd alloy obtained after complete homogenization annealing in Example 1 is very uniform in the distribution of titanium and palladium, and almost no other impurities and phases can be seen around the α titanium grains.

[0058] Example 1: According to the mass ratio of the required titanium target alloy, a portion of sponge titanium is first mixed with palladium in a mass ratio of 98:2 to prepare a titanium-palladium intermediate alloy strip. Compared with directly mixing all the sponge titanium and palladium to prepare the titanium target alloy, the palladium content is higher, which is beneficial to improve the uniformity of the distribution of titanium and palladium; it is prepared by rapid cooling of the melt. According to the Ti-Pd alloy phase diagram, the two are completely miscible at high temperatures. Smelting can make Pd completely dissolve in titanium, and rapid cooling and quenching prevent Pd from precipitating, forming TiPd instead of Ti2Pd or TiPd3, which can avoid the occurrence of component segregation between the two during the solidification process, thereby ensuring the uniformity of the distribution of the two and laying a solid foundation for the subsequent electrode remelting. The thickness of the strip is 40-60 microns and the width is 5-10 mm, which is conducive to rapid cooling and subsequent crushing or pulverization. The morphology of the titanium-palladium intermediate alloy strip with a similar morphology to sponge titanium obtained in step 2 of Example 1 after initial crushing is as follows Figure 6 As shown in step 4 of Example 1, the morphology of the titanium sponge and the titanium palladium alloy after mixing is as follows: Figure 7 shown.

[0059] Example 2,

[0060] A method for preparing a homogeneous titanium-palladium alloy comprises the following steps:

[0061] Step 1, raw material preparation: commercially available titanium sponge (grade 0) and palladium gold fragments (particle size 100 mesh, purity ≥99%) are used; the particle size of titanium sponge is 100 mesh.

[0062] Step 2: Preparation of titanium-palladium master alloy strip: Weigh titanium sponge and palladium gold in a mass ratio of 96:4 and place them in a vacuum chamber with a degree of 9×10 -3 The melt was rapidly melted in a vacuum induction melting furnace in a melt quenching equipment with a current of 40A and accompanied by magnetic stirring for 3 minutes; after waiting for melting, it was kept for 3 minutes and then filled with argon. Under argon protection (argon pressure 0.3 MPa), it was quenched with the help of a water-cooled copper roller 18 at 2000 rpm to form a titanium-palladium intermediate alloy strip with a thickness of 40 microns and a width of 5 mm.

[0063] Step 3, fragmentation treatment of the titanium-palladium master alloy: crushing the titanium-palladium master alloy prepared in step 2 into titanium-palladium master alloy fragments (chips) using a crusher. The size of the titanium-palladium master alloy fragments is the same as the particle size of sponge titanium.

[0064] Step 4: Mixing titanium sponge and titanium palladium master alloy: Weigh titanium sponge and titanium palladium master alloy sheets in a mass ratio of 8:2, and mix them in a blade mixer at a speed of 200 rpm for 60 minutes. Figure 3 The sampling method shown is used, and the calculated deviation δ is no more than 5%.

[0065] Step 5: Cold pressing of titanium-palladium electrode blocks: The mixture from step 4 is loaded into a steel cold pressing mold of fixed size (the mold size can be adjusted arbitrarily according to production needs, and the loading amount is the product of the mold cavity volume and the density of titanium). The mixture is pressed under a pressing pressure of 800 MPa into a block of a certain strength (guaranteed by the density) and a certain shape (guaranteed by the mold), i.e., a titanium-palladium electrode with a density of 4.3 g / cm 3 .

[0066] Step 6. Preparation of titanium-palladium alloy ingot: The titanium-palladium electrode obtained in step 5 is placed in a vacuum consumable electrode furnace (vacuum degree is 0.05 Pa) and melted three times with an arc current of 1 kA, a melting current of 3 kA, and a voltage of 20 V to obtain a titanium-palladium alloy ingot; the axial movement speed of the consumable electrode is 15 mm / min; the process parameters of the three meltings are the same, this step is vacuum consumable electrode zone melting, the cooling and solidification rate is consistent with the heating melting rate, and it melts and cools at the same time.

[0067] Step 7: Homogenization annealing treatment: The titanium-palladium alloy ingot obtained in step 6 is kept in a vacuum annealing furnace at a temperature of 550°C for 10 hours with a vacuum degree of 10 -1 Pa, and then furnace cooling to obtain a titanium-palladium alloy ingot with uniform structure and composition.

[0068] Figure 8 This is the metallographic structure of the titanium-palladium alloy prepared in Example 2. The distribution of titanium and palladium is very uniform, and no obvious component segregation or impurities are observed.

[0069] Example 3,

[0070] A method for preparing a homogeneous titanium-palladium alloy comprises the following steps:

[0071] Step 1, raw material preparation: commercially available titanium sponge (grade 0) and palladium gold fragments (particle size 200 mesh, purity ≥99%) are used; the particle size of titanium sponge is 200 mesh.

[0072] Step 2: Preparation of titanium-palladium master alloy strip: Weigh titanium sponge and palladium gold in a mass ratio of 97:3 and place them in a vacuum chamber with a degree of vacuum of 0.6×10 -3 Pa melt rapid melting in a vacuum induction melting furnace with a current of 20A, accompanied by magnetic stirring for 10 minutes; wait for 10 minutes after melting, then fill with argon, and under argon protection (argon pressure 0.5MPa) with the help of a 5000 rpm water-cooled copper roller 18 to quickly cool into a titanium-palladium intermediate alloy strip with a thickness of 60 microns and a width of 10 mm.

[0073] Step 3, fragmentation treatment of the titanium-palladium master alloy: crushing the titanium-palladium master alloy prepared in step 2 into titanium-palladium master alloy fragments (chips) using a crusher. The size of the titanium-palladium master alloy fragments is the same as the particle size of sponge titanium.

[0074] Step 4: Mixing titanium sponge and titanium palladium master alloy: Weigh titanium sponge and titanium palladium master alloy sheets in a mass ratio of 7:3, and mix them in a blade mixer at a speed of 500 rpm for 30 minutes. Figure 3 The sampling method shown is used, and the calculated deviation δ is no more than 5%.

[0075] Step 5: Cold pressing of titanium-palladium electrode blocks: The mixture prepared in step 4 is loaded into a steel cold pressing mold of fixed size (the mold size can be adjusted arbitrarily according to production needs, and the loading amount is the product of the mold cavity volume and the density of titanium). The mixture is pressed under a pressing pressure of 600 MPa for 10 seconds to form a block with a certain strength (guaranteed by the density) and a certain shape (guaranteed by the mold), i.e., a titanium-palladium electrode with a density of 4.0 g / cm 3 .

[0076] Step 6. Preparation of titanium-palladium alloy ingot: The titanium-palladium electrode obtained in step 5 is placed in a vacuum consumable electrode furnace (vacuum degree is 0.01 Pa) and smelted four times with an arc current of 2kA, a melting current of 2kA, and a voltage of 25V to obtain a titanium-palladium alloy ingot. The axial movement speed of the consumable electrode is 20mm / min; the process parameters of the four smeltings are the same.

[0077] Step 7: Homogenization annealing treatment: The titanium-palladium alloy ingot obtained in step 6 is kept in a vacuum annealing furnace at a temperature of 600°C for 6 hours with a vacuum degree of 10 -3 Pa, and then furnace cooling to obtain a titanium-palladium alloy ingot with uniform structure and composition.

[0078] Figure 9 This is the metallographic structure of the titanium-palladium alloy prepared in Example 3. The distribution of titanium and palladium is very uniform, and no obvious component segregation or impurities are observed.

[0079] In step 2 of Examples 1-3, vacuum induction melting (VIM) melts the metal based on the principle of electromagnetic induction. The temperature is controlled by the applied frequency and current (determined through multiple experiments, with an auxiliary infrared thermometer displaying 1800-1900°C). The time is also determined by the amount of raw materials added, multiple experiments, or by observing the alloy through an observation port to see if it has melted (melting time is generally about 15-25 minutes). After melting, the molten metal is allowed to stand for about 3-10 minutes before being poured through a pouring riser onto a high-speed, water-cooled copper roller. Vacuum induction melting is coupled with the subsequent rapid cooling process and does not exist independently, so there is no inherent cooling rate. The cooling end of the quenching equipment has a dedicated pouring riser. Its dimensions (10-15 mm wide and 3-7 mm high) match the dimensions of the water-cooled copper roller (5-10 mm wide U-shaped groove) to produce a titanium-palladium intermediate alloy ribbon of the desired thickness and width.

[0080] The schematic structure of the titanium-palladium master alloy ribbon prepared by rapid cooling of the melt in step 2 of Example 1-3 is as follows: Figure 1 As shown, high-pressure inert gas is introduced into the vacuum induction melting furnace, a heater coil 15 is provided on the outer wall of a quartz tube 13, and molten metal 14 is ejected from the bottom of the quartz tube 13 in the form of a molten metal jet 16 onto the surface of a high-speed rotating water-cooled copper roller 18, forming a thin strip 17 of titanium-palladium master alloy.

[0081] In the fourth step of Example 1-3, the mixing equipment adopts a blade mixer, which is a high-efficiency mixing equipment with high mixing efficiency and low mixing intensity, ensuring that the materials reach the required particle size without being further crushed; the structure is as follows Figure 2As shown, the mixing box 3 includes a mixing box 3 with legs 2 at the bottom, a base 1 at the lower end of the legs 2, and an inclined reinforcing rod 12 between the legs 2 and the base 1; a hopper 4 is provided at the top of the mixing box 3, and an inverted V-shaped side panel 5 is provided directly below the hopper 4. A rubber plate 10 is provided on the inner wall of the mixing box 3 below the side panel 5. The bottom of the rubber plate 10 is provided with a spring 11, which can provide a certain buffering effect when the material is poured, preventing the mixed material from undergoing work hardening or inducing phase change or grinding on the material box (introducing other impurities) due to the impact, so that the mixed material flows slowly into the mixing box and reduces the mixing intensity; a discharge port 6 is provided on the side wall of the mixing box 3; an agitator is provided inside the mixing box 3, and the agitator is provided with blades 9. A drive device is provided on the outer side of the bottom of the mixing box 3. When the equipment is in operation, the drive device drives the agitator to rotate, and the blades on the agitator apply shear force, friction force, and turning force to the material, so that the materials of different components are fully contacted and evenly distributed in the container. A side wall of the mixing box 3 is provided with a sleeve box 7 and a pull rod 8 for collecting finer mixed materials. If the material is too fine, it is not suitable for subsequent mixing and molding because the fine powder will fill the gaps in the coarse powder, affecting the ratio and uniformity.

[0082] Figure 3 In the calculation, the radius R of the sampling circle is much larger than the particle radius r, R = 100r ~ 1000r. If the sampling circle is too small, the calculation cannot be completed, or the calculation accuracy is poor. If the sampling circle is too large, the number of particles in the circle is difficult to count clearly, or it can be counted clearly, but it takes too long.

[0083] Comparative Example 1,

[0084] A method for preparing a titanium-palladium alloy: excluding steps 2 and 3, and otherwise the same as in Example 1; that is, titanium powder and palladium powder are directly mechanically mixed (without using an intermediate alloy), cold-pressed, and then smelted twice in a vacuum consumable electrode area to obtain the alloy.

[0085] The microstructure of the titanium-palladium alloy prepared in Comparative Example 1 is as follows: Figure 10a As shown, some dark grey uneven titanium palladium or palladium can be seen on the titanium substrate.

[0086] Comparative Example 2,

[0087] A method for preparing a titanium-palladium alloy: without step 7, the remaining steps are the same as those in Example 1. The metallographic structure of the titanium-palladium alloy ingot is as follows: Figure 10b As shown, the composition is relatively uniform, but the tissue uniformity is poor.

[0088] Comparative Example 3,

[0089] A method for preparing a titanium-palladium alloy: Step 2, Step 3, and Step 6 are omitted, and the rest is the same as in Example 2; that is, titanium powder and palladium powder are mixed and then smelted three times in a vacuum arc furnace (needs to be cold pressed into blocks first).

[0090] The microstructure of the titanium-palladium alloy prepared in Comparative Example 3 is as follows: Figure 10c As shown, obvious composition segregation can be seen even at lower magnifications.

[0091] The homogeneous titanium-palladium alloy prepared by the preparation method of the present invention is mainly used in the medical and health field (many medical products are made of titanium, and the material is usually used as the base material or raw material of these products), and is also partially used in the petroleum and chemical fields with special requirements. On the one hand, it is required to have high corrosion resistance, and on the other hand, it must have certain mechanical strength. To this end, the content of alloying elements cannot be too much, and it must be a single-phase structure to avoid galvanic corrosion due to multiphase structure, or abnormal grain growth or tissue stress caused by the difference in potential energy on both sides of the grain boundary due to the unevenness of the grains, thereby causing premature failure.

[0092] The titanium-palladium alloy to be prepared must have a palladium content of no more than 0.2%. This small amount, combined with the requirement for uniform distribution, presents significant challenges. The present invention involves first preparing a high-Pd-content master alloy. Sponge titanium and palladium gold fragments are placed in a mass ratio of 96-98:4-2, and then subjected to multiple arc melting processes (vacuum induction melting in step 2) to achieve maximum compositional uniformity. Second, the master alloy is further enhanced by rapid quenching. Third, the titanium sponge and titanium-palladium master alloy fragments (of comparable particle size to the titanium sponge) are mechanically mixed at a mass ratio of 8-9:2-1, and the mixing uniformity is tested. Exceeding this mass ratio will not only fail to meet the user's palladium content requirements, but also increase costs, as palladium is very expensive. Every 0.1% increase in the price of the titanium-palladium alloy increases the price by approximately 5%. Fourth, electrode-area remelting is performed to ensure that mixing uniformity is maintained during the melting process. Fifth, homogenization annealing is performed to further improve this lack of uniformity, thereby achieving a highly uniform titanium-palladium alloy billet.

[0093] The above description is only a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention are included in the scope of protection of the present invention.

Claims

1. A method for preparing a homogeneous titanium-palladium alloy, characterized in that: The following steps are involved: Step 1, raw material preparation: titanium sponge with a particle size of 100-200 mesh and palladium gold fragments with a particle size of 100-200 mesh; Step 2: Place titanium sponge and palladium gold fragments in a vacuum induction melting furnace in a melt quenching device in a mass ratio of 96-98:4-2, rapidly melt them, and stir them with magnetic stirring for 3-10 minutes. After melting, hold them for 3-10 minutes, and then quench them under argon protection into a titanium-palladium master alloy with a thickness of 40-60 microns and a width of 5-10 mm. Step 3, crushing the titanium-palladium master alloy into titanium-palladium master alloy fragments having the same particle size as the titanium sponge; Step 4, weighing titanium sponge and titanium-palladium master alloy fragments in a mass ratio of 8-9:2-1, and physically mixing them evenly; Step 5: The mixture prepared in step 4 is placed into a steel cold pressing mold of fixed size and pressed into a compact under a pressing pressure of 600-800 MPa, i.e., a titanium palladium electrode; Step 6: The titanium-palladium electrode is repeatedly smelted in a vacuum consumable electrode furnace to obtain a titanium-palladium alloy ingot; Step seven, subjecting the titanium-palladium alloy ingot to homogenization annealing treatment in a vacuum annealing furnace to obtain the product.

2. The method for preparing a homogeneous titanium-palladium alloy according to claim 1, characterized in that: In the step 1, the titanium sponge is commercially available grade 0 titanium sponge, and the purity of the palladium gold fragments is ≥99%.

3. The method for preparing a homogeneous titanium-palladium alloy according to claim 1, characterized in that: In the step 2, the vacuum degree of the vacuum induction melting furnace is 9×10 -3 Pa~6×10 -4 Pa, the current of the vacuum induction melting furnace is 20~40A.

4. The method for preparing a homogeneous titanium-palladium alloy according to claim 1, wherein: In the step 2, the rapid cooling is achieved by a water-cooled copper roller at 2000 to 5000 rpm.

5. The method for preparing a homogeneous titanium-palladium alloy according to claim 1, wherein: In the step 4, physical mixing is performed in a blade mixer with titanium sputtered on the surface, with the blade rotating at a speed of 200 to 500 rpm and the mixing time being 30 to 60 minutes.

6. The method for preparing a homogeneous titanium-palladium alloy according to claim 1, characterized in that: In step 4, after physical mixing, randomly sample the mixture and observe its uniformity under a microscope, or randomly determine a sampling circle for the mixture, then weigh the mass of the particles in the sampling circle, and count the number of particles in the circle, and use the following formula to calculate the deviation: Where: M x With m x They are the total number of particles contained in the sampling circle with a radius of R and the total mass of the corresponding particles, r is the radius of the mixed material particles, that is, the particle radius of sponge titanium; C'0 is a constant, ranging from 1 to 3; δ represents the deviation number. When the calculated deviation number δ is not greater than 5%, the mixing has achieved the required uniformity.

7. The method for preparing a homogeneous titanium-palladium alloy according to claim 1, characterized in that: In the step 5, the titanium palladium electrode density is 4.0-4.3 g / cm 3 .

8. The method for preparing a homogeneous titanium-palladium alloy according to claim 1, characterized in that: In the step six, arc melting is carried out in a vacuum consumable electrode furnace with a vacuum degree of 1 Pa to 0.01 Pa, an arc starting current of 1 to 2 kA, a melting current of 2 to 3 kA, and a voltage of 20 to 25 V; and the axial movement speed of the consumable electrode is 10 to 20 mm / min.

9. The method for preparing a homogeneous titanium-palladium alloy according to claim 1, characterized in that: In the step 7, the titanium-palladium alloy ingot is kept in a vacuum annealing furnace at a temperature of 550-600°C for 6-10 hours, and the vacuum degree is 10 -1 ~10 -3 Pa, then the furnace is cooled, and you get it.

10. Application of the homogeneous titanium-palladium alloy prepared by the method for preparing a homogeneous titanium-palladium alloy according to claim 1 in the fields of medical care, health care and petrochemical industry.

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