Palladium-containing low-melting-point nickel-based alloy, brazing filler metal, preparation method and application

Abstract

The invention discloses a palladium-containing low-melting-point nickel-based alloy, brazing filler metal, a preparation method and application, and belongs to the technical field of metal brazing. The palladium-containing low-melting-point nickel-based alloy comprises the following raw materials in percentage by mass: 20%-40% of palladium, 5%-15% of chromium, 0.5%-8% of silicon, 2.0%-4.0% of boron, 0-1.0% of yttrium and the balance of nickel. The purity of each raw material is not less than 99.99%. The brazing filler metal prepared from the palladium-containing low-melting-point nickel-based alloy further comprises a binding agent. The mass ratio of the nickel-based alloy to the binder is 1: (0.05-0.3), and the binder is propylene glycol or resin. Compared with traditional nickel-based high-temperature brazing filler metal, the palladium-containing nickel-based brazing filler metal can remarkably reduce the brazing temperature of GH4169 high-temperature nickel-based alloy, performance damage of a high-temperature environment to base metal in the welding process can be avoided, and the overall comprehensive performance of a connector is improved.

Description

Technical Field

[0001] The invention relates to the technical field of metal brazing, and more particularly to a palladium-containing low-melting-point nickel-based alloy, a brazing material, and a preparation method and application thereof. Background Art

[0002] GH4169 alloy is an aging precipitation-strengthened nickel-based high-temperature alloy (foreign grade Inconel718). The alloy structure consists of matrix γ phase, δ phase, main strengthening phase, auxiliary strengthening phase and carbide. The alloy has excellent comprehensive mechanical properties and process properties below 650℃ and is the most widely used material for hot end components of aircraft engines. The amount, morphology and distribution of δ phase in GH4169 alloy have a great influence on its deformation behavior and mechanical properties. Among them, δ phase can promote dynamic recrystallization nucleation, pin grain boundaries and inhibit grain growth. The appropriate amount of δ phase can also improve the plasticity of the alloy and reduce notch sensitivity. The δ phase in GH4169 alloy precipitates at 780℃~980℃, starts to dissolve after the temperature exceeds 980℃, and will be completely dissolved in the γ matrix when the temperature rises to about 1020℃, seriously affecting the alloy's creep, high temperature durability and other properties.

[0003] At present, brazing precision connection technology is used for some GH4169 nickel-based alloy engine hot end parts with complex shapes and structures. However, at too high a brazing process temperature, the δ phase will dissolve and the alloy grains will grow rapidly, resulting in serious damage to the high-temperature durability of the GH4169 alloy after welding. Even after post-weld solution and aging treatment, it still cannot be completely restored to the pre-weld state.

[0004] Therefore, in order to ensure the post-welding performance of GH4169 nickel-based high-temperature alloy as much as possible, it is a technical problem that technical personnel in this field urgently need to solve to develop a palladium-containing low-melting-point nickel-based brazing filler metal with a lower melting point, good wettability and filling ability below the δ phase solid solution temperature (under 980°C welding conditions), and excellent joint mechanical properties. Summary of the invention

[0005] In view of this, the present invention provides a palladium-containing low-melting-point nickel-based alloy, a brazing material, and a preparation method and application. The present invention utilizes the melting-reducing effect of palladium on nickel and the improvement of high-temperature performance of brazed joints by yttrium, so that the melting point of the brazing material is reduced by 40-60°C, and the wettability of the brazing material and the overall strength of the joint can be improved. After adding 1% yttrium, the high-temperature durability of the brazed joint can be improved by 20%.

[0006] One of the purposes of the present invention is to provide a palladium-containing low-melting-point nickel-based alloy, wherein the raw material composition of the alloy is, in terms of mass percentage:

[0007] 20% to 40% palladium, 5% to 15% chromium, 0.5% to 8% silicon, 2.0% to 4.0% boron, 0% to 1.0% yttrium, and the balance is nickel;

[0008] Wherein, the purity of each raw material constituting the alloy is not less than 99.99%.

[0009] The second object of the present invention is to provide a palladium-containing low-melting-point nickel-based solder, comprising the palladium-containing low-melting-point nickel-based alloy and a binder; the mass ratio of the palladium-containing low-melting-point nickel-based alloy to the binder is 1:0.05-0.3.

[0010] Preferably, the binder is propylene glycol or resin.

[0011] More preferably, the resin is a styrene copolymer.

[0012] The beneficial effect of adopting the above technical solution is that the palladium-containing low-melting-point nickel-based alloy can realize vacuum welding of high-temperature nickel-based alloy at a relatively low temperature (980° C.).

[0013] The third object of the present invention is to provide a method for preparing a palladium-containing low-melting-point nickel-based alloy, comprising the following steps:

[0014] (1) Weighing each raw material according to mass percentage, ultrasonically cleaning the raw material in an acetone solution for 15 minutes, then ultrasonically cleaning the raw material in an alcohol solution for 5 minutes, and drying for later use;

[0015] (2) uniformly mixing a nickel raw material, a chromium raw material, a palladium raw material, a silicon raw material, a boron raw material, and a yttrium raw material, placing the mixture in a vacuum arc melting furnace, evacuating the mixture to a low vacuum and then filling the mixture with argon, and repeatedly melting the mixture four times to obtain a nickel-based alloy ingot, which is then taken out from the vacuum arc melting furnace after cooling, and the surface metal scum is removed by grinding to obtain the palladium-containing low-melting-point nickel-based alloy.

[0016] Preferably, in step (1), the concentration of the acetone solution is 99.5%.

[0017] Preferably, in step (2), the vacuum degree of the low vacuum is 1×10 -1 Pa, the repeated smelting is performed at an interval of 5 minutes each time, the smelting temperature is 1200-1300°C, and the smelting time is 10-30 minutes, so that each element can be fully diffused and fused.

[0018] The beneficial effect of adopting the above technical solution is that it can ensure that the composition ratio of the palladium-containing low-melting-point nickel-based alloy is stable and does not contain excessive impurities.

[0019] The fourth object of the present invention is to provide a method for preparing a palladium-containing low-melting-point nickel-based solder, the specific operation of which is: preparing the palladium-containing low-melting-point nickel-based alloy into an amorphous sheet or powder.

[0020] Preferably, the thickness of the amorphous sheet is 40-500 μm; and the particle size of the powder is 5-100 μm.

[0021] Further preferably, the preparation method further comprises: weighing the palladium-containing low-melting-point nickel-based alloy powder and the binder according to a mass ratio, mixing them evenly, and preparing a solder paste.

[0022] The beneficial effects of adopting the above further technical solution are: the binder can improve the fluidity of the solder, making it easier to apply it to the workpiece, and at the same time can remove oxides on the surface of the base material and the solder, thereby improving the welding quality.

[0023] A fifth object of the present invention is to provide an application of a palladium-containing low-melting-point nickel-based brazing filler metal, and an application of the palladium-containing low-melting-point nickel-based brazing filler metal in the brazing of nickel-based high-temperature alloys, stainless steel or cobalt-based high-temperature alloys.

[0024] It can be seen from the above technical solution that compared with the prior art, the present invention has the following beneficial effects:

[0025] The present invention utilizes the melting reduction effect of palladium on nickel and the improvement of high temperature performance of brazed joints by yttrium, so that the melting point of the brazing material is reduced by 40-60°C, and the wettability of the brazing material and the overall strength of the joint can be improved. After adding 0.5% yttrium, the high temperature durability of the brazing joint can be improved by 20%. The main problems solved are: optimizing the content of chromium, palladium, silicon, boron and nickel. Adding silicon, boron and palladium can significantly reduce the solidus and liquidus of the brazing material, and improve the wetting and filling performance of the brazing material; adding chromium can play a role in solid solution strengthening, improve the strength of the brazing material, and also improve the anti-oxidation performance of the brazing material; adding rare earth element yttrium can significantly improve the high temperature durability of the brazing joint. Compared with traditional nickel-based high temperature brazing material, the palladium-containing nickel-based brazing material can significantly reduce the brazing temperature of GH4169 high temperature nickel-based alloy. The present invention can avoid the damage to the performance of the parent material by the high temperature environment during the welding process, so that the overall comprehensive performance of the joint can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0027] Figure 1 Pd-Ni binary phase diagram

[0028] Figure 2 Pd-B binary phase diagram

[0029] Figure 3Pd-Si binary phase diagram

[0030] Figure 4 DSC curve of solder of Example 1;

[0031] Figure 5 SEM microstructure morphology of solder welded joint in Example 1;

[0032] Figure 6 Mechanical property curve of solder welding joint in Example 1;

[0033] Figure 7 DSC curve of solder of Example 2;

[0034] Figure 8 DSC curve of solder of Example 3;

[0035] Fig. 9 DSC curve of solder of Example 4;

[0036] Fig.10 Mechanical property curve of solder welded joint in Example 4;

[0037] Fig.11 a) original GH4169 metallographic image; b) metallographic image of Example 1 after soldering at 980°C for 1h. DETAILED DESCRIPTION

[0038] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments 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 creative work are within the scope of protection of the present invention.

[0039] Example 1

[0040] The preparation method of palladium-containing low-melting-point nickel-based solder comprises the following steps:

[0041] (1) a palladium-containing low-melting-point nickel-based alloy, wherein the weight percentages of the chemical components are: 10% chromium, 36% palladium, 1% silicon, 3% boron, and the balance is nickel. Various high-purity raw materials are weighed according to the above weight percentages, and the raw materials are ultrasonically cleaned in an acetone solution for 15 minutes, and then ultrasonically cleaned in an alcohol solution for 5 minutes, and dried for standby use. The purity of various high-purity raw materials is not less than 99.99%;

[0042] (2) mixing a nickel raw material, a chromium raw material, a palladium raw material, a silicon raw material, and a boron raw material uniformly, heating and smelting them in an electric arc furnace under an argon protective atmosphere for 4 times at a smelting temperature of 1300° C. for a total smelting time of 20 minutes to obtain a bulk alloy;

[0043] (3) The bulk alloy is made into an amorphous sheet. The preparation method of the amorphous sheet is a single-roller rapid cooling method. The thickness of the amorphous sheet is 50 μm.

[0044] The melting point of the solder obtained in Example 1 was tested. The melting point of the solder was 828.82-961.43°C ( Figure 4 shown).

[0045] The high temperature alloy GH4169 was brazed with the brazing temperature of 980℃ and the holding time of 20 minutes. After brazing, the metallographic structure of the brazed joint was observed and the welding quality of the joint was good. Figure 6 The tensile strength of the joint obtained by the brazing material under the above brazing parameters can reach 530MPa to 580MPa, reaching 92.8% of the parent material. Figure 3 As shown, the high temperature endurance performance (650℃ / 200MPa) exceeds 10h.

[0046] Example 2

[0047] The preparation method of palladium-containing low-melting-point nickel-based solder comprises the following steps:

[0048] (1) a palladium-containing low-melting-point nickel-based alloy, wherein the weight percentages of the chemical components are: 9.6% chromium, 27% palladium, 7.3% silicon, 2.35% boron, and the balance is nickel. Various high-purity raw materials are weighed according to the above weight percentages, and the raw materials are ultrasonically cleaned in an acetone solution for 15 minutes, and then ultrasonically cleaned in an alcohol solution for 5 minutes, and dried for standby use. The purity of various high-purity raw materials is not less than 99.99%;

[0049] (2) mixing nickel raw material, chromium raw material, palladium raw material, silicon raw material and boron raw material uniformly, heating and repeatedly smelting in an electric arc furnace under an argon protective atmosphere for 4 times, the smelting temperature is 1300° C., and the total smelting time is 15 minutes to obtain a bulk alloy;

[0050] (3) The bulk alloy is made into powder. The powder is prepared by atomization powder spraying method. The particle size of the powder is 5-15 μm.

[0051] The powder and the styrene copolymer are weighed in a mass ratio of 1:0.1. The powder and the binder are mixed evenly and rolled to prepare a bonding solder.

[0052] The melting point of the solder obtained in Example 2 was tested, and the melting point of the solder composition was 850.91-960.70°C (as shown in FIG. Figure 7 shown).

[0053] The high temperature alloy GH4169 was brazed with the brazing filler metal of this composition, the brazing temperature was 980℃, and the holding time was 2 hours. The joint welding quality was good, the weld width was 55μm, and the joint tensile strength was 450-480MPa.

[0054] Example 3

[0055] The preparation method of palladium-containing low-melting-point nickel-based solder comprises the following steps:

[0056] (1) a palladium-containing low-melting-point nickel-based alloy, wherein the weight percentages of the chemical components are: 9.2% chromium, 23% palladium, 7.1% silicon, 2.4% boron, and the balance is nickel. Various high-purity raw materials are weighed according to the above weight percentages, and the raw materials are ultrasonically cleaned in an acetone solution for 15 minutes, and then ultrasonically cleaned in an alcohol solution for 5 minutes, and dried for standby use. The purity of various high-purity raw materials is not less than 99.99%;

[0057] (2) mixing nickel raw material, chromium raw material, palladium raw material, silicon raw material and boron raw material uniformly, heating and smelting in an electric arc furnace under an argon protective atmosphere for 4 times at a smelting temperature of 1300° C. for a total smelting time of 30 minutes to obtain a bulk alloy;

[0058] (3) The bulk alloy is made into powder. The powder is prepared by atomization powder spraying method. The particle size of the powder is 20-50 μm.

[0059] The above powder and propylene glycol were weighed in a mass ratio of 1:0.2, and the powder and the binder were evenly mixed to prepare a solder paste.

[0060] The melting point of the solder powder obtained in Example 3 was tested. The melting point of the solder powder was 852.59-941.62°C ( Figure 8 shown).

[0061] The high temperature alloy GH4169 was brazed with the brazing temperature of 980℃ and the holding time of 2h. The joint welding quality was good, the weld width was 62μm, and the joint tensile strength was 380-420MPa.

[0062] Example 4

[0063] The preparation method of palladium-containing low-melting-point nickel-based solder comprises the following steps:

[0064] (1) a palladium-containing low-melting-point nickel-based alloy, wherein the weight percentages of the chemical components are: 9.5% chromium, 25% palladium, 7% silicon, 2.2% boron, 0.5% yttrium, and the balance is nickel. Various high-purity raw materials are weighed according to the above weight percentages, and the raw materials are ultrasonically cleaned in an acetone solution for 15 minutes, and then ultrasonically cleaned in an alcohol solution for 5 minutes, and dried for standby use. The purity of various high-purity raw materials is not less than 99.99%;

[0065] (2) mixing a nickel raw material, a chromium raw material, a palladium raw material, a silicon raw material, a boron raw material, and a yttrium raw material uniformly, heating and melting them in an electric arc furnace under an argon protective atmosphere, the melting temperature is 1300° C., and the total melting time is 30 minutes to obtain a bulk alloy;

[0066] (3) The bulk alloy is made into powder. The powder is prepared by atomization powder spraying method. The particle size of the powder is 20-50 μm.

[0067] Weigh the above powder and propylene glycol in a mass ratio of 1:0.2, mix the powder and the binder evenly to make a solder paste.

[0068] The melting point of the solder powder obtained in Example 4 was tested. The melting point of the solder powder was 945.36°C to 979.76°C ( Fig. 9 shown).

[0069] The high temperature alloy GH4169 was brazed with the brazing temperature of 980℃ and the holding time of 2h. The joint welding quality was good and the tensile strength of the joint was 600MPa (such as Fig.10 As shown), high temperature endurance performance (650℃ / 200MPa) exceeds 12h.

[0070] The technical concept of the raw material components and preparation method of the present invention is:

[0071] Palladium has good plasticity and high temperature performance, but its melting point is relatively high (1555°C). According to the Pd-Ni phase diagram ( Figure 1 ), when the palladium content is 60%, a low melting solid solution is formed, and its melting point is 1237 ℃, but the melting point is still relatively high. In order to further lower its melting point, Si, B and other melting-reducing elements can be added.

[0072] Pd-B phase diagram Figure 2 As shown in the figure, a eutectic point is formed at B-2.6% (mass), and its melting point is 850°C. Therefore, the melting point of Pd-B eutectic is much lower than that of Ni-B eutectic (1045°C), and adding less B can lower its melting point. In addition, the solubility of boron in palladium is relatively large. At the eutectic temperature, the solubility of boron in palladium reaches 2.3% (mass), and the alloy is less brittle.

[0073] Pd-Si phase diagram Figure 3 As shown in the figure, similar to the Ni-Si phase diagram, the solubility of silicon in palladium is less than 0.1%, and a eutectic reaction is formed at 15.5% Si (atoms), with a melting point of 780° C. Therefore, adding a small amount of Si to Pd can achieve the purpose of lowering its melting point.

[0074] Therefore, boron and silicon have a more significant effect on reducing the melting point of nickel-palladium alloy than nickel-based solder. Adding Cr to solder improves its oxidation resistance. Through experimental research, it is found that the melting point of solder is lower when the Cr content is about 11%.

[0075] The structure of Pd solder consists of nickel (palladium) solid solution, eutectic composed of nickel (palladium) solid solution and nickel boride, and a small amount of chromium boride. Because the solder contains more solid solution, the hardness is lower and the plasticity is better than that of nickel-based solder.

[0076] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A palladium-containing low-melting-point nickel-based alloy, characterized in that: The raw material composition is, in terms of mass percentage, 20% to 40% palladium, 5% to 15% chromium, 0.5% to 8% silicon, 2.0% to 4.0% boron, 0% to 1.0% yttrium, and the balance is nickel; The purity of each raw material is not less than 99.99%.

2. A palladium-containing low-melting-point nickel-based solder, characterized in that: It comprises the palladium-containing low-melting-point nickel-based alloy as described in claim 1.

3. A palladium-containing low-melting-point nickel-based solder according to claim 2, characterized in that: It also includes a binder, and the mass ratio of the palladium-containing low-melting-point nickel-based alloy to the binder is 1:0.05-0.

3.

4. A palladium-containing low-melting-point nickel-based solder according to claim 3, characterized in that: The binder is propylene glycol or resin.

5. The palladium-containing low-melting-point nickel-based solder according to claim 3, characterized in that: The resin is a styrene copolymer.

6. A method for preparing a palladium-containing low-melting-point nickel-based alloy, characterized in that: The following steps are involved: (1) Weighing each raw material according to the mass percentage of claim 1, ultrasonically cleaning the raw materials in an acetone solution for 15 minutes, then ultrasonically cleaning them in an alcohol solution for 5 minutes, and drying them for later use; (2) uniformly mixing a nickel raw material, a chromium raw material, a palladium raw material, a silicon raw material, a boron raw material, and a yttrium raw material, placing the mixture in a vacuum arc melting furnace, evacuating the mixture to a low vacuum and then filling the mixture with argon, and repeatedly melting the mixture four times to obtain a nickel-based alloy ingot, which is then taken out from the vacuum arc melting furnace after cooling, and the surface metal scum is removed by grinding to obtain the palladium-containing low-melting-point nickel-based alloy.

7. The method for preparing a palladium-containing low-melting-point nickel-based alloy according to claim 6, characterized in that: In step (2), the vacuum degree of the low vacuum is 1×10 -1 Pa, the repeated smelting is performed at an interval of 5 minutes each time, the smelting temperature is 1200-1300° C., and the total smelting time is 10-30 minutes.

8. A method for preparing a palladium-containing low-melting-point nickel-based solder, characterized in that: The palladium-containing low-melting-point nickel-based alloy according to any one of claims 6-7 is made into an amorphous sheet or powder.

9. The method for preparing a palladium-containing low-melting-point nickel-based solder according to claim 8, characterized in that: Also includes: The palladium-containing low-melting-point nickel-based alloy powder and the binder are weighed according to the mass ratio of claim 3, mixed evenly, and made into solder paste.

10. An application of a palladium-containing low-melting-point nickel-based solder, characterized in that: Application of the palladium-containing low-melting-point nickel-based brazing filler metal prepared according to any one of claims 8-9 in the brazing of nickel-based high-temperature alloys, stainless steel or cobalt-based high-temperature alloys.

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