Nickel-chromium high-temperature interalloy, its preparation method and application

Abstract

The present application relates to nickel-chromium alloy preparation technical field, specifically relates to a kind of nickel-chromium high-temperature intermediate alloy and its preparation method and application, the steps of the preparation method are: raw material preparation, furnace loading, vacuum extraction, smelting, deoxidizing refining, casting and furnace discharge;The present application prepares nickel-chromium niobium intermediate alloy by adopting vacuum induction smelting method, and the prepared nickel-chromium niobium intermediate alloy is low in gas content, few in inclusion and uniform in composition;The application carefully designs the combination, processing mode and macrostructure of high-temperature interface alloy component, so that the interface of composite alloy gradually and continuously transitions from metal component to ceramic component, eliminates the interface difference as much as possible, makes the composite alloy part present macrostructure inhomogeneity and microscopic structure continuity, and solves the interface cracking problem caused by the difference in physical and chemical properties between high-temperature alloy and ceramic material in composite alloy part.

Description

Technical Field

[0001] This invention relates to the field of nickel-chromium alloy preparation technology, specifically to a nickel-chromium high-temperature intermediate alloy, its preparation method, and its application. Background Technology

[0002] High-temperature alloys, due to their excellent high-temperature resistance, are mainly used in fields such as aero-engines and gas turbines. As the thrust-to-weight ratio of aero-engines continues to increase, the operating environment of gas turbines is becoming increasingly harsh, thus placing higher demands on high-temperature alloys and leading to increasingly higher alloying degrees in these alloys.

[0003] For nickel-based superalloys, the main alloying elements added include Cr, Co, W, Mo, Al, Ti, V, and Nb. The amount of these alloying elements added has been increasing from 25% to about 45%. With the increasing degree of alloying, the melting point differences between the added alloying elements have also become larger. For example, the melting point of electrolytic nickel is 1453℃, that of metallic chromium is 1856℃, and that of metallic niobium is 2468℃. To ensure that the high-melting-point elements can melt, the melting temperature is continuously increased, inevitably leading to the volatilization of low-melting-point elements. To balance the differences in melting temperatures among various elements, a large amount of various master alloys are added during the high-temperature alloy smelting process. The most important added elements in nickel-based superalloys are Cr, with a content generally around 20%, and Nb, with a content generally around 7%. Therefore, the amount of nickel-chromium-niobium master alloy used is large, and the quality requirements are also very high. How to develop a high-quality nickel-chromium-niobium master alloy to improve the overall performance of nickel-based superalloys is an urgent problem to be solved in this field. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a nickel-chromium high-temperature intermediate alloy, its preparation method, and its application.

[0005] This invention discloses a nickel-chromium high-temperature intermediate alloy, the composition of which is as follows:

[0006] Cr: 14.0–15%, Nb: 34.3–35%, Si: 0.031–0.04%, Al: 0.059–0.07%, Fe: 0.051–0.06%, C: 0.014–0.02%, S: 0.016–0.02%, O: 0.012–0.02%, N: 0.0078–0.008%, Ni is the balance.

[0007] Note: For nickel-based superalloys, the main alloying elements added include Cr, Co, W, Mo, Al, Ti, V, and Nb. The amount of these alloying elements added increases from 25% to approximately 45%. With the increasing degree of alloying, the melting point differences between the added alloying elements also become more pronounced. For example, the melting point of electrolytic nickel is 1453℃, metallic chromium is 1856℃, and metallic niobium is 2468℃. If the metals are added directly in elemental form, compositional segregation can easily occur due to differences in melting point and density. Preparing nickel-chromium-niobium alloys with specific compositions using a master alloy as raw material during vacuum induction melting can effectively improve the stability of the alloy.

[0008] The present invention discloses a method for preparing a nickel-chromium high-temperature master alloy, comprising the following steps:

[0009] SA1. Raw material preparation: Prepare metal materials according to design requirements, ensuring that each component in the metal material meets the requirements by weight percentage.

[0010] SA2, Loading the furnace: Load the prepared metal material into the vacuum induction furnace, and use a CaO crucible for melting;

[0011] SA3. Vacuuming: Turn on the mechanical pump and open the low vacuum baffle valve to evacuate the vacuum. When the vacuum pressure inside the vacuum furnace is below 0.08 MPa, turn on the Roots pump.

[0012] SA4. Melting: When the vacuum pressure in the vacuum furnace is lower than ≤0.1Pa, heat up: First, increase the power from zero to 20-30KW and hold for 5-10 minutes; then increase the power to 40-50KW and hold for 5-10 minutes; finally, increase the power to 60-70KW and maintain this power until the metal in the crucible is completely melted.

[0013] SA5, Deoxidation and Refining: After all the metal material has been melted, add the deoxidizer through the secondary feeding funnel, keep the power constant, and deoxidize for 10 to 15 minutes;

[0014] SA6, Casting: Reduce the power to 25-35KW, maintain for 5-6 minutes, and then begin casting;

[0015] SA7. Unloading: After casting is completed, turn off the heating and cool for 60 minutes before unloading to obtain a nickel-chromium high-temperature intermediate alloy, denoted as NiCrNb intermediate alloy.

[0016] Note: Nickel-chromium-niobium master alloys were prepared by vacuum induction melting. These master alloys have low gas content, few inclusions, and uniform composition.

[0017] This invention also provides an application of the above-mentioned nickel-chromium high-temperature master alloy, which is used to prepare nickel-chromium high-temperature composite alloy parts, the steps of which include:

[0018] SB1. Preparation of high-temperature alloy matrix:

[0019] A high-temperature alloy matrix, denoted as NiCrNb matrix, was prepared by melting and casting using NiCrNb master alloy as raw material.

[0020] SB2, Preparation of high-temperature interface alloy components:

[0021] SB2-1, Mixed Powder: Using the NiCrNb master alloy in SB1 as raw material, NiCrNb alloy powder with a particle size range of 20-40 μm is prepared by plasma rotating electrode atomization method; ZrO2 powder doped with 3 mol% Y2O3 is prepared; NiCrNb alloy powder and ZrO2 powder are mixed evenly in batches according to design requirements.

[0022] SB2-2, Design of Alloy Gradient Bonding Layer Parameters: A 3D model of the part is designed using 3DP technology, and the alloy gradient bonding layer parameters are designed based on slicing software.

[0023] Z0: ZrO2 powder: 0 vol%, NiCrNb alloy powder: 100 vol%, layer thickness: 0.15~0.2 mm;

[0024] Z1: ZrO2 powder: 20 vol%, NiCrNb alloy powder: 80 vol%, layer thickness: 0.15~2 mm;

[0025] Z2: ZrO2 powder: 40 vol%, NiCrNb alloy powder: 60 vol%, layer thickness: 0.1~0.15 mm;

[0026] Z3: ZrO2 powder: 50 vol%, NiCrNb alloy powder: 50 vol%, layer thickness: 0.1~0.15 mm;

[0027] Z4: ZrO2 powder: 60 vol%, NiCrNb alloy powder: 40 vol%, layer thickness: 0.1~0.15 mm;

[0028] Z5: ZrO2 powder: 80 vol%, NiCrNb alloy powder: 20 vol%, layer thickness: 0.15~0.2 mm;

[0029] Z6: ZrO2 powder: 100 vol%, NiCrNb alloy powder: 0 vol%, layer thickness: 0.15~0.2 mm;

[0030] SB2-3, Bonding and Sintering: According to the shape and layer thickness parameters of the part in SB2-2, the mixed powder and binder are sprayed layer by layer, and the binder is removed by high-temperature sintering to obtain a high-temperature interface alloy component, which is denoted as ZrO2-NiCrNb component;

[0031] SB3. Preparation of nickel-chromium high-temperature composite alloy parts:

[0032] First, the ZrO2-NiCrNb component in SB2-3 is dried at a gradient temperature, then bonded to the NiCrNb matrix in SB1-2, and finally the nickel-chromium high-temperature composite alloy parts are obtained by vacuum hot pressing sintering at 140-160 MPa.

[0033] Furthermore, the method for uniformly mixing NiCrNb alloy powder and ZrO2 powder in batches according to design requirements in SB2-1 is as follows: using a star ball mill, firstly, NiCrNb alloy powder and ZrO2 powder are mixed with ethanol, then mixed at 350-400 r / min for 24 h, and finally the mixed powder is freeze-dried and ground for later use.

[0034] The temperature gradient for freeze drying is as follows: first, the temperature is lowered from room temperature to -30℃ within 8–10 min and held for 5–7 min; then, the temperature is lowered from -30℃ to -60℃ within 8–10 min and held for 20–25 min; finally, the temperature is lowered from -60℃ to -70℃ within 4–5 min and held for 18–20 h.

[0035] Note: Using a star-shaped ball mill for alloy powder mixing ensures uniform powder mixing, thus guaranteeing stable quality of the prepared alloy material. Furthermore, using ethanol to mix the powder facilitates better contact between the material and the ball mill spheres, further enhancing the mixing effect.

[0036] Freeze-drying is a method of converting solid substances into dried products, commonly used in the preparation of alloy materials to remove moisture and maintain material stability. Employing a suitable freeze-drying temperature gradient can effectively preserve the original properties of powders and reduce the formation of voids within the raw material when gases escape at high speeds.

[0037] Furthermore, the components of the binder in SB2-3 are listed in the following volume ratios: ethanol: 10-15%, ethylene glycol: 4-7%, phenolic resin: balance; the viscosity of the binder is 6.2-6.5 mPa·s, the surface tension is 24-26 mN / m, and the saturation is 25-30%.

[0038] The temperature gradient for removing the binder by high-temperature sintering is as follows: first, the temperature is increased from room temperature to 500℃ within 10-15 minutes and held for 20-30 minutes; then, the temperature is increased from 500℃ to 850℃ within 10-15 minutes and held for 20-30 minutes; finally, the temperature is increased from 850℃ to 1000℃ within 5-10 minutes and held for 50-60 minutes.

[0039] Note: The high-temperature sintering process for removing binders effectively and completely removes the binder from the material, ensuring that the prepared material does not produce volatiles or residues at high temperatures. By gradually heating and holding the temperature, the binder can be completely burned and decomposed within a certain time, thus achieving complete removal.

[0040] Furthermore, the vacuum hot pressing sintering method in SB3 is as follows:

[0041] SB3-1. The ZrO2-NiCrNb component in SB2-3 is dried in an oven. The temperature gradient of the oven is as follows: first, the temperature is raised from room temperature to 60℃ in 3-4 minutes and held for 8-10 minutes; then, the temperature is raised from 60℃ to 100℃ in 3-5 minutes and held for 30-40 minutes; finally, the temperature is raised from 100℃ to 200℃ in 20-30 minutes and held for 1-1.5 hours.

[0042] SB3-2. The NiCrNb matrix in SB1 is bonded to the Z0 layer surface of the ZrO2-NiCrNb component treated by SB3-1 to obtain a composite alloy billet.

[0043] SB3-3. Under an external pressure of 5 to 10 MPa, the composite alloy billet is sintered at the following temperature gradient to obtain nickel-chromium high-temperature composite alloy parts.

[0044] The temperature gradient during sintering of the composite alloy billet is as follows: first, the temperature is increased from room temperature to 700℃ at a rate of 10–12℃ / min and held for 25–35 min; then, the temperature is increased from 700℃ to 1250℃ at a rate of 5–7℃ / min and held for 60–70 min; finally, the temperature is decreased from 1250℃ to 800℃ at a rate of 5–7℃ / min and held for 60–70 min.

[0045] Description: The ZrO2-NiCrNb component prepared by this invention has a layered gradient structure, in which NiCrNb alloy and ZrO2 powder are uniformly distributed, gradually transitioning from ceramic components to metal components, exhibiting macroscopic inhomogeneity and microscopic continuity; the above-mentioned ZrO2-NiCrNb component can effectively buffer the physicochemical differences between NiCrNb intermediate alloy and ceramic material, thereby strengthening the bonding strength between the two.

[0046] Compared with existing methods for preparing nickel-chromium high-temperature master alloys, the advantages of this invention are:

[0047] (1) The present invention prepares nickel-chromium-niobium master alloy by using vacuum induction melting method. The nickel-chromium-niobium master alloy prepared by this method has low gas content, few inclusions and uniform composition.

[0048] (2) By designing the combination, processing method and macrostructure of ZrO2-NiCrNb components, this invention enables the interface of the composite alloy to gradually and continuously transition from the metal component to the ceramic component, thereby eliminating interface differences as much as possible. This allows the composite alloy parts to exhibit macroscopic inhomogeneity and microscopic continuity, solving the problem of interface cracking caused by the difference in physicochemical properties between high-temperature alloys and ceramic materials in composite alloy parts. Attached Figure Description

[0049] Figure 1 This is a metallographic image of the nickel-chromium high-temperature intermediate alloy prepared according to the present invention.

[0050] Figure 2 This is a macroscopic morphology diagram of the nickel-chromium high-temperature intermediate alloy prepared by this invention. Detailed Implementation

[0051] To further illustrate the methods and effects of this invention, the technical solution of this invention will be clearly and completely described below in conjunction with experiments.

[0052] Example 1: This example describes a nickel-chromium high-temperature intermediate alloy and its preparation method.

[0053] The preparation method of nickel-chromium high-temperature master alloy includes the following steps:

[0054] SA1. Raw material preparation: Prepare metal materials according to design requirements, ensuring that each component in the metal material meets the requirements by weight percentage.

[0055] SA2, Loading the furnace: Load the prepared metal material into the vacuum induction furnace, and use a CaO crucible for melting;

[0056] SA3. Vacuuming: Turn on the mechanical pump and open the low vacuum baffle valve to evacuate the vacuum. When the vacuum pressure inside the vacuum furnace is below 0.08 MPa, turn on the Roots pump.

[0057] SA4, Melting: When the vacuum pressure in the vacuum furnace is lower than ≤0.1Pa, heat up: First, increase the power from zero to 20KW and hold for 5 minutes; then increase the power to 40KW and hold for 5 minutes; finally, increase the power to 60KW and maintain this power until the metal in the crucible is completely melted.

[0058] SA5, Deoxidation and Refining: After all the metal material has been melted, add silicon-aluminum-iron alloy through a secondary feeding funnel, keep the power constant, and deoxidize for 10 minutes;

[0059] SA6, Casting: Reduce the power to 25KW, maintain for 5 minutes, and then begin casting;

[0060] SA7. Unloading: After casting is completed, turn off the heating and cool for 60 minutes before unloading to obtain a nickel-chromium high-temperature intermediate alloy, denoted as NiCrNb intermediate alloy.

[0061] The composition of the nickel-chromium high-temperature master alloy prepared by the above method is as follows:

[0062] Cr: 14.0%, Nb: 34.3%, Si: 0.031%, Al: 0.059%, Fe: 0.051%, C: 0.014%, S: 0.016%, O: 0.012%, N: 0.0078%, Ni is the balance.

[0063] Example 2: This example describes a nickel-chromium high-temperature intermediate alloy and its preparation method.

[0064] The preparation method of nickel-chromium high-temperature master alloy includes the following steps:

[0065] SA1. Raw material preparation: Prepare metal materials according to design requirements, ensuring that each component in the metal material meets the requirements by weight percentage.

[0066] SA2, Loading the furnace: Load the prepared metal material into the vacuum induction furnace, and use a CaO crucible for melting;

[0067] SA3. Vacuuming: Turn on the mechanical pump and open the low vacuum baffle valve to evacuate the vacuum. When the vacuum pressure inside the vacuum furnace is below 0.08 MPa, turn on the Roots pump.

[0068] SA4, Melting: When the vacuum pressure in the vacuum furnace is lower than ≤0.1Pa, heat up: first, increase the power from zero to 30KW and hold for 10min; then increase the power to 50KW and hold for 10min; finally, increase the power to 70KW and maintain this power until the metal in the crucible is completely melted.

[0069] SA5, Deoxidation and Refining: After all the metal material has been melted, add silicon-aluminum-iron alloy through a secondary feeding funnel, keep the power constant, and deoxidize for 15 minutes;

[0070] SA6, Casting: Reduce power to 35KW, maintain for 6 minutes, and then begin casting;

[0071] SA7. Unloading: After casting is completed, turn off the heating and cool for 60 minutes before unloading to obtain a nickel-chromium high-temperature intermediate alloy, denoted as NiCrNb intermediate alloy.

[0072] The composition of the nickel-chromium high-temperature master alloy prepared by the above method is as follows:

[0073] Cr: 15%, Nb: 35%, Si: 0.04%, Al: 0.07%, Fe: 0.06%, C: 0.02%, S: 0.02%, O: 0.02%, N: 0.008%, Ni is the balance.

[0074] Example 3: The content described in this example is based on the nickel-chromium high-temperature intermediate alloy prepared in Example 1, specifically the application of the nickel-chromium high-temperature intermediate alloy.

[0075] SB1. Preparation of high-temperature alloy matrix:

[0076] A high-temperature alloy matrix, denoted as NiCrNb matrix, was prepared by melting and casting using NiCrNb master alloy as raw material.

[0077] SB2, Preparation of high-temperature interface alloy components:

[0078] SB2-1, Mixed Powder: Using the NiCrNb master alloy in SB1 as raw material, NiCrNb alloy powder with a particle size range of 20μm is prepared by plasma rotating electrode atomization method; ZrO2 powder doped with 3mol% Y2O3 is prepared; NiCrNb alloy powder and ZrO2 powder are mixed evenly in batches according to design requirements.

[0079] The method for achieving uniform mixing is as follows: using a star-shaped ball mill, firstly, NiCrNb alloy powder and ZrO2 powder are mixed with ethanol at a mass ratio of material:liquid = 2:1, then mixed at 350 r / min for 24 h, and finally the mixed powder is freeze-dried and ground for later use.

[0080] The temperature gradient for freeze drying is as follows: first, the temperature is lowered from room temperature to -30°C within 8 minutes and held for 5 minutes; then, the temperature is lowered from -30°C to -60°C within 8 minutes and held for 20 minutes; finally, the temperature is lowered from -60°C to -70°C within 4 minutes and held for 18 hours.

[0081] SB2-2, Design of Alloy Gradient Bonding Layer Parameters: A 3D model of the part is designed using 3DP technology, and the alloy gradient bonding layer parameters are designed based on slicing software.

[0082] Z0: ZrO2 powder: 0 vol%, NiCrNb alloy powder: 100 vol%, layer thickness: 0.15 mm;

[0083] Z1: ZrO2 powder: 20 vol%, NiCrNb alloy powder: 80 vol%, layer thickness: 0.15 mm;

[0084] Z2: ZrO2 powder: 40 vol%, NiCrNb alloy powder: 60 vol%, layer thickness: 0.1 mm;

[0085] Z3: ZrO2 powder: 50 vol%, NiCrNb alloy powder: 50 vol%, layer thickness: 0.15 mm;

[0086] Z4: ZrO2 powder: 60 vol%, NiCrNb alloy powder: 40 vol%, layer thickness: 0.1 mm;

[0087] Z5: ZrO2 powder: 80 vol%, NiCrNb alloy powder: 20 vol%, layer thickness: 0.15 mm;

[0088] Z6: ZrO2 powder: 100 vol%, NiCrNb alloy powder: 0 vol%, layer thickness: 0.15 mm;

[0089] SB2-3, Bonding and Sintering: According to the shape and layer thickness parameters of the part in SB2-2, the mixed powder and binder are sprayed layer by layer, and the binder is removed by high-temperature sintering to obtain a high-temperature interface alloy component, which is denoted as ZrO2-NiCrNb component;

[0090] The components of the adhesive are listed in the following volume ratios: ethanol: 10%, ethylene glycol: 4%, phenolic resin: balance; the adhesive has a viscosity of 6.2 mPa·s, a surface tension of 24 mN / m, and a saturation of 25%.

[0091] The temperature gradient for removing the binder by high-temperature sintering is as follows: first, the temperature is increased from room temperature to 500℃ within 10 minutes and held for 20 minutes; then, the temperature is increased from 500℃ to 850℃ within 10 minutes and held for 20 minutes; finally, the temperature is increased from 850℃ to 1000℃ within 5 minutes and held for 50 minutes.

[0092] SB3. Preparation of nickel-chromium high-temperature composite alloy parts:

[0093] First, the ZrO2-NiCrNb component in SB2-3 is dried at a gradient temperature, then bonded to the NiCrNb matrix in SB1-2, and finally, the nickel-chromium high-temperature composite alloy part is obtained by vacuum hot pressing sintering at 140 MPa. Specifically:

[0094] SB3-1. The ZrO2-NiCrNb component in SB2-3 is dried in an oven. The temperature gradient of the oven is as follows: first, the temperature is increased from room temperature to 60℃ in 3 minutes and held for 8 minutes; then, the temperature is increased from 60℃ to 100℃ in 3 minutes and held for 30 minutes; finally, the temperature is increased from 100℃ to 200℃ in 20 minutes and held for 1 hour.

[0095] SB3-2. The NiCrNb matrix in SB1 is bonded to the Z0 layer surface of the ZrO2-NiCrNb component treated by SB3-1 to obtain a composite alloy billet.

[0096] SB3-3. Under an external pressure of 5 MPa, the composite alloy billet is sintered at the following temperature gradient to obtain nickel-chromium high-temperature composite alloy parts.

[0097] The temperature gradient during sintering of the composite alloy billet is as follows: first, the temperature is increased from room temperature to 700℃ at a heating rate of 10℃ / min and held for 25 min; then, the temperature is increased from 700℃ to 1250℃ at a heating rate of 5℃ / min and held for 60 min; finally, the temperature is decreased from 1250℃ to 800℃ at a cooling rate of 5℃ / min and held for 60 min.

[0098] Example 4: The content described in this example is based on the nickel-chromium high-temperature intermediate alloy prepared in Example 1, specifically the application of the nickel-chromium high-temperature intermediate alloy.

[0099] SB1. Preparation of high-temperature alloy matrix:

[0100] A high-temperature alloy matrix, denoted as NiCrNb matrix, was prepared by melting and casting using NiCrNb master alloy as raw material.

[0101] SB2, Preparation of high-temperature interface alloy components:

[0102] SB2-1, Mixed Powder: Using the NiCrNb master alloy in SB1 as raw material, NiCrNb alloy powder with a particle size range of 40μm is prepared by plasma rotating electrode atomization method; ZrO2 powder doped with 3mol% Y2O3 is prepared; NiCrNb alloy powder and ZrO2 powder are mixed evenly in batches according to design requirements.

[0103] The method for achieving uniform mixing is as follows: using a star-shaped ball mill, firstly, NiCrNb alloy powder and ZrO2 powder are mixed with ethanol at a mass ratio of material:liquid = 2:1, then mixed at 400 r / min for 24 h, and finally the mixed powder is freeze-dried and ground for later use.

[0104] The temperature gradient for freeze drying is as follows: first, the temperature is lowered from room temperature to -30°C within 10 minutes and held for 7 minutes; then, the temperature is lowered from -30°C to -60°C within 10 minutes and held for 25 minutes; finally, the temperature is lowered from -60°C to -70°C within 5 minutes and held for 20 hours.

[0105] SB2-2, Design of Alloy Gradient Bonding Layer Parameters: A 3D model of the part is designed using 3DP technology, and the alloy gradient bonding layer parameters are designed based on slicing software.

[0106] Z0: ZrO2 powder: 0 vol%, NiCrNb alloy powder: 100 vol%, layer thickness: 0.2 mm;

[0107] Z1: ZrO2 powder: 20 vol%, NiCrNb alloy powder: 80 vol%, layer thickness: 0.15 mm;

[0108] Z2: ZrO2 powder: 40 vol%, NiCrNb alloy powder: 60 vol%, layer thickness: 0.1 mm;

[0109] Z3: ZrO2 powder: 50 vol%, NiCrNb alloy powder: 50 vol%, layer thickness: 0.1 mm;

[0110] Z4: ZrO2 powder: 60 vol%, NiCrNb alloy powder: 40 vol%, layer thickness: 0.1 mm;

[0111] Z5: ZrO2 powder: 80 vol%, NiCrNb alloy powder: 20 vol%, layer thickness: 0.15 mm;

[0112] Z6: ZrO2 powder: 100 vol%, NiCrNb alloy powder: 0 vol%, layer thickness: 0.2 mm;

[0113] SB2-3, Bonding and Sintering: According to the shape and layer thickness parameters of the part in SB2-2, the mixed powder and binder are sprayed layer by layer, and the binder is removed by high-temperature sintering to obtain a high-temperature interface alloy component, which is denoted as ZrO2-NiCrNb component;

[0114] The components of the adhesive are listed in the following volume ratios: ethanol: 15%, ethylene glycol: 7%, phenolic resin: balance; the adhesive has a viscosity of 6.5 mPa·s, a surface tension of 26 mN / m, and a saturation of 30%.

[0115] The temperature gradient for removing the binder by high-temperature sintering is as follows: first, the temperature is increased from room temperature to 500℃ within 15 minutes and held for 30 minutes; then, the temperature is increased from 500℃ to 850℃ within 15 minutes and held for 30 minutes; finally, the temperature is increased from 850℃ to 1000℃ within 10 minutes and held for 60 minutes.

[0116] SB3. Preparation of nickel-chromium high-temperature composite alloy parts:

[0117] First, the ZrO2-NiCrNb component in SB2-3 is dried at a gradient temperature, then bonded to the NiCrNb matrix in SB1-2, and finally, the nickel-chromium high-temperature composite alloy part is obtained by vacuum hot pressing sintering at 160 MPa. Specifically:

[0118] SB3-1. The ZrO2-NiCrNb component in SB2-3 is dried in an oven. The temperature gradient of the oven is as follows: first, the temperature is increased from room temperature to 60℃ in 4 minutes and held for 10 minutes; then, the temperature is increased from 60℃ to 100℃ in 5 minutes and held for 40 minutes; finally, the temperature is increased from 100℃ to 200℃ in 30 minutes and held for 1.5 hours.

[0119] SB3-2. The NiCrNb matrix in SB1 is bonded to the Z0 layer surface of the ZrO2-NiCrNb component treated by SB3-1 to obtain a composite alloy billet.

[0120] SB3-3. Under an external pressure of 10 MPa, the composite alloy billet is sintered at the following temperature gradient to obtain nickel-chromium high-temperature composite alloy parts.

[0121] The temperature gradient during sintering of the composite alloy billet is as follows: first, the temperature is increased from room temperature to 700℃ at a heating rate of 12℃ / min and held for 35min; then, the temperature is increased from 700℃ to 1250℃ at a heating rate of 7℃ / min and held for 70min; finally, the temperature is decreased from 1250℃ to 800℃ at a cooling rate of 7℃ / min and held for 70min.

[0122] Example 5: The content described in this example is based on the scheme in Example 4, and mainly illustrates a more specific application of the design scheme of the present invention; in this example, a porcelain crown will be designed using the scheme in Example 2.

[0123] SB1. Preparation of high-temperature alloy matrix:

[0124] A high-temperature alloy matrix, denoted as NiCrNb matrix, was prepared by melting and casting using NiCrNb master alloy as raw material.

[0125] SB2, Preparation of high-temperature interface alloy components:

[0126] SB2-1, Mixed Powder: Using the NiCrNb master alloy in SB1 as raw material, a high-temperature alloy matrix is ​​prepared by melting and casting, which is the high-temperature alloy bridge body for porcelain crowns;

[0127] SB2, Preparation of high-temperature interface alloy components:

[0128] SB2-1, Mixed Powder: Using the NiCrNb master alloy in SB1-1 as raw material, NiCrNb alloy powder with a particle size range of 40μm is prepared by plasma rotating electrode atomization method; ZrO2 powder doped with 3mol% Y2O3 is prepared; NiCrNb alloy powder and ZrO2 powder are mixed evenly in batches according to design requirements.

[0129] The method for achieving uniform mixing is as follows: using a star-shaped ball mill, firstly, NiCrNb alloy powder and ZrO2 powder are mixed with ethanol at a mass ratio of material:liquid = 2:1, then mixed at 400 r / min for 24 h, and finally the mixed powder is freeze-dried and ground for later use.

[0130] The temperature gradient for freeze drying is as follows: first, the temperature is lowered from room temperature to -30°C within 10 minutes and held for 7 minutes; then, the temperature is lowered from -30°C to -60°C within 10 minutes and held for 25 minutes; finally, the temperature is lowered from -60°C to -70°C within 5 minutes and held for 20 hours.

[0131] SB2-2, Design of Alloy Gradient Bonding Layer Parameters: A 3D model of the part is designed using 3DP technology, and the alloy gradient bonding layer parameters are designed based on slicing software.

[0132] Z0: ZrO2 powder: 0 vol%, NiCrNb alloy powder: 100 vol%, layer thickness: 0.2 mm;

[0133] Z1: ZrO2 powder: 20 vol%, NiCrNb alloy powder: 80 vol%, layer thickness: 0.15 mm;

[0134] Z2: ZrO2 powder: 40 vol%, NiCrNb alloy powder: 60 vol%, layer thickness: 0.1 mm;

[0135] Z3: ZrO2 powder: 50 vol%, NiCrNb alloy powder: 50 vol%, layer thickness: 0.1 mm;

[0136] Z4: ZrO2 powder: 60 vol%, NiCrNb alloy powder: 40 vol%, layer thickness: 0.1 mm;

[0137] Z5: ZrO2 powder: 80 vol%, NiCrNb alloy powder: 20 vol%, layer thickness: 0.15 mm;

[0138] Z6: ZrO2 powder: 100 vol%, NiCrNb alloy powder: 0 vol%, layer thickness: 0.2 mm;

[0139] SB2-3, Bonding and Sintering: According to the shape and layer thickness parameters of the part in the 3D drawing in SB2-2, the mixed powder and binder are sprayed layer by layer, and the binder is removed by high-temperature sintering to obtain a high-temperature interface alloy component;

[0140] The components of the adhesive are listed in the following volume ratios: ethanol: 15%, ethylene glycol: 7%, phenolic resin: balance; the adhesive has a viscosity of 6.5 mPa·s, a surface tension of 26 mN / m, and a saturation of 30%.

[0141] The temperature gradient for removing the binder by high-temperature sintering is as follows: first, the temperature is increased from room temperature to 500℃ within 15 minutes and held for 30 minutes; then, the temperature is increased from 500℃ to 850℃ within 15 minutes and held for 30 minutes; finally, the temperature is increased from 850℃ to 1000℃ within 10 minutes and held for 60 minutes.

[0142] SB3. Preparation of nickel-chromium high-temperature composite alloy parts:

[0143] First, the high-temperature interface alloy component of SB2-3 is dried at a gradient temperature, then combined with the high-temperature alloy bridge body of SB1-2, and finally, the nickel-chromium high-temperature composite alloy part, i.e., the high-temperature alloy inner crown of the porcelain crown, is obtained by vacuum hot pressing sintering at 160MPa. Specifically:

[0144] SB3-1. The ZrO2-NiCrNb component in SB2-3 is dried in an oven. The temperature gradient of the oven is as follows: first, the temperature is increased from room temperature to 60℃ in 4 minutes and held for 10 minutes; then, the temperature is increased from 60℃ to 100℃ in 5 minutes and held for 40 minutes; finally, the temperature is increased from 100℃ to 200℃ in 30 minutes and held for 1.5 hours.

[0145] SB3-2. The NiCrNb matrix in SB1 is bonded to the Z0 layer surface of the ZrO2-NiCrNb component treated by SB3-1 to obtain a composite alloy billet.

[0146] SB3-3. Under an external pressure of 10 MPa, the composite alloy billet is sintered at the following temperature gradient to obtain a high-temperature alloy inner crown;

[0147] The temperature gradient during sintering of the composite alloy billet is as follows: first, the temperature is increased from room temperature to 700℃ at a heating rate of 12℃ / min and held for 35min; then, the temperature is increased from 700℃ to 1250℃ at a heating rate of 7℃ / min and held for 70min; finally, the temperature is decreased from 1250℃ to 800℃ at a cooling rate of 7℃ / min and held for 70min.

[0148] SB4, firing porcelain crowns: First, the Z6 layer of the high-temperature alloy inner crown prepared by SB3 is coated with the base porcelain and the veneer porcelain, and then the porcelain crown is obtained by high-temperature sintering.

[0149] SB4-1. High-strength dental ceramic powder is used as the base porcelain, and Songfeng Vintage AL powder is used as the veneer porcelain. The high-strength dental ceramic powder and Songfeng Vintage AL powder are evenly dispersed in a mixing liquid at a powder-to-liquid mass ratio of 7:1 to prepare the base porcelain slurry and the veneer porcelain slurry.

[0150] SB4-2. First, fix the Z6 layer of the high-temperature alloy inner crown in the mold, then pour the bottom layer of porcelain slurry, and after it is formed, pour the top layer of porcelain slurry with a thickness of 0.2mm. After forming, the porcelain crown blank is obtained.

[0151] SB4-3, high-temperature sintering of the porcelain tooth blank in SB4-2 to obtain porcelain teeth; the temperature gradient of the high-temperature sintering is as follows: first, the temperature is increased from room temperature to 300℃ at a heating rate of 60℃ / min and held for 5min; then, the temperature is increased from 300℃ to 600℃ at a heating rate of 100℃ / min and held for 6min; finally, the temperature is increased from 600℃ to 900℃ at a heating rate of 120℃ / min and held for 5min.

[0152] Experimental Example: The description of this experimental example is based on the description scheme in Example 5, and aims to describe the actual performance of the product prepared by the present invention.

[0153] 1. Experimental Design

[0154] To clarify the specific properties of the porcelain crowns prepared according to this invention, the following experimental group was designed:

[0155] Blank group: Without preparing ZrO2-NiCrNb gradient bonding parts, the bridge body and inner crown were directly prepared with NiCr master alloy, and the facing porcelain was directly sintered on the inner crown.

[0156] Control group 1: Without preparing ZrO2-NiCrNb gradient bonding parts, an integral bridge body and inner crown were directly prepared using NiCrNb master alloy, and the decorative porcelain was directly sintered onto the inner crown.

[0157] Control group 2: Without preparing ZrO2-NiCrNb gradient bonding parts, an integral bridge and inner crown were directly prepared using NiCrNb master alloy, and the bottom layer ceramic and the decorative ceramic were sintered on the inner crown in sequence.

[0158] Control Group 3: A ZrO2-NiCrNb gradient bond was prepared. The high-temperature alloy inner crown was fabricated using the steps outlined in Example 5. The alloy gradient bond layer parameters were:

[0159] Z0: ZrO2 powder: 0 vol%, NiCrNb alloy powder: 100 vol%, layer thickness: 0.2 mm;

[0160] Z1: ZrO2 powder: 50 vol%, NiCrNb alloy powder: 50 vol%, layer thickness: 0.2 mm;

[0161] Z2: ZrO2 powder: 100 vol%, NiCrNb alloy powder: 0 vol%, layer thickness: 0.2 mm;

[0162] Control group 4: Preparation of ZrO2-NiCrNb gradient bonding component. A high-temperature alloy inner crown was prepared using the steps described in Example 5. The alloy gradient bonding layer parameters were:

[0163] Z0: ZrO2 powder: 0 vol%, NiCrNb alloy powder: 100 vol%, layer thickness: 0.2 mm;

[0164] Z1: ZrO2 powder: 25 vol%, NiCrNb alloy powder: 75 vol%, layer thickness: 0.15 mm;

[0165] Z2: ZrO2 powder: 50 vol%, NiCrNb alloy powder: 50 vol%, layer thickness: 0.1 mm;

[0166] Z3: ZrO2 powder: 70 vol%, NiCrNb alloy powder: 25 vol%, layer thickness: 0.15 mm;

[0167] Z4: ZrO2 powder: 100 vol%, NiCrNb alloy powder: 0 vol%, layer thickness: 0.2 mm;

[0168] Control Group 5: Preparation of ZrO2-NiCrNb gradient bonding components. A high-temperature alloy inner crown was prepared using the steps outlined in Example 5. The alloy gradient bonding layer parameters were:

[0169] Z0: ZrO2 powder: 0 vol%, NiCrNb alloy powder: 100 vol%, layer thickness: 0.2 mm;

[0170] Z1: ZrO2 powder: 20 vol%, NiCrNb alloy powder: 80 vol%, layer thickness: 0.15 mm;

[0171] Z2: ZrO2 powder: 40 vol%, NiCrNb alloy powder: 60 vol%, layer thickness: 0.1 mm;

[0172] Z3: ZrO2 powder: 50 vol%, NiCrNb alloy powder: 50 vol%, layer thickness: 0.1 mm;

[0173] Z4: ZrO2 powder: 60 vol%, NiCrNb alloy powder: 40 vol%, layer thickness: 0.1 mm;

[0174] Z5: ZrO2 powder: 80 vol%, NiCrNb alloy powder: 20 vol%, layer thickness: 0.15 mm;

[0175] Z6: ZrO2 powder: 100 vol%, NiCrNb alloy powder: 0 vol%, layer thickness: 0.2 mm.

[0176] 2. Relevant performance experiments

[0177] The sample prepared in the above experimental example was placed in a fixture to test the bonding strength of the ceramic layer of the high-temperature alloy inner crown; the alloy inner crown was fixed, and the loading head was in contact with the ceramic surface through a rubber pad. The loading speed was 0.5 mm / min, and the instantaneous pressure value when the ceramic surface peeled off and broke from the high-temperature alloy inner crown was recorded. The specific data are shown in Table 1.

[0178] Table 1. Peeling pressure values ​​of porcelain surfaces on porcelain-fused-to-metal crowns with different structures.

[0179]

[0180] Comparing control group 1 and blank group, it can be seen that when ZrO2-NiCrNb gradient bonding is not prepared, the bonding strength of metal-based ceramic matrix on porcelain teeth is relatively low. In addition, the doping of niobium has little effect on the bonding strength between metal matrix and ceramic matrix, which can be ignored. Its main effect is on the mechanical strength and toughness of the metal matrix itself.

[0181] Comparing control group 2 and control group 1, it can be seen that when the veneer porcelain is fired directly on the metal substrate, the bonding strength between the veneer porcelain and the metal substrate is relatively low. However, when a base layer of porcelain is first coated on the metal substrate, and then the veneer porcelain is coated, the bonding strength between the metal substrate and the ceramic substrate in the fired ceramic teeth is improved. This is because the Al2O3 in the high-strength ceramic powder can bond the veneer porcelain and the metal substrate through glass penetration during the sintering process, thereby improving the bonding strength between the two.

[0182] Comparing control group 3 and control group 2, it can be seen that the ZrO2-NiCrNb component, as an intermediate "buffer layer", gradually and continuously transitions from the metal component to the ceramic component, which can effectively eliminate the interface difference between the metal matrix and the ceramic matrix, thereby significantly improving the bonding strength between the two.

[0183] Comparing control groups 3, 4, and 5, it can be seen that as the number of ZrO2-NiCrNb components decreases, i.e., the differences in physicochemical properties between layers are reduced, the bonding strength between the metal and ceramic matrix in porcelain-fused-to-metal (PFM) crowns can be effectively improved. In particular, in control group 5, the peeling pressure of the ceramic matrix from the metal matrix reached 70.15 MPa, representing a 45.16% increase in bonding strength compared to the conventional preparation method (control group 2). Therefore, the ZrO2-NiCrNb component with a layered gradient structure prepared in this invention can effectively improve the overall strength and service life of PFM crowns.

Claims

1. An application of a nickel-chromium high-temperature master alloy, characterized in that, The nickel-chromium high-temperature intermediate alloy has the following composition: Cr: 14.0~15%, Nb: 34.3~35%, Si: 0.031~0.04%, Al: 0.059~0.07%, Fe: 0.051~0.06%, C: 0.014~0.02%, S: 0.016~0.02%, O: 0.012~0.02%, N: 0.0078~0.008%, Ni is the balance; The preparation method of the nickel-chromium high-temperature master alloy includes the following steps: SA1. Raw material preparation: Prepare metal materials according to design requirements, ensuring that each component in the metal material meets the requirements by weight percentage. SA2, Loading the furnace: Load the prepared metal material into the vacuum induction furnace, and use a CaO crucible for melting; SA3. Vacuuming: Turn on the mechanical pump and open the low vacuum baffle valve to evacuate the vacuum. When the vacuum pressure inside the vacuum furnace is below 0.08 MPa, turn on the Roots pump. SA4, Melting: When the vacuum pressure in the vacuum furnace is lower than ≤0.1Pa, heat up: First, increase the power from zero to 20~30kW and hold for 5~10min; then increase the power to 40~50kW and hold for 5~10min; finally, increase the power to 60~70kW and maintain this power until the metal in the crucible is completely melted. SA5, Deoxidation and Refining: After all the metal material has been melted, add the deoxidizer through the secondary feeding funnel, keep the power constant, and deoxidize for 10~15 minutes. SA6, Casting: Reduce the power to 25~35 kW, maintain for 5~6 minutes, and then begin casting; SA7. Unloading: After casting, turn off the heating and allow it to cool for 60 minutes before unloading to obtain a nickel-chromium high-temperature intermediate alloy, denoted as SA7. Intermediate alloy; The steps for using the nickel-chromium high-temperature master alloy to prepare nickel-chromium high-temperature composite alloy parts include: SB1. Preparation of high-temperature alloy matrix: by Using intermediate alloys as raw materials, high-temperature alloy matrices are prepared by melting and casting, denoted as... Matrix; SB2, Preparation of high-temperature interface alloy components: SB2-1, Mixed Powder: Based on SB1 Using intermediate alloys as raw materials, particles with a size range of 20–40 μm were prepared by plasma rotating electrode atomization. Alloy powder; prepared with 3 mol% doping of Powder; the powder; Alloy powder and The powder is mixed evenly in batches according to design requirements; SB2-2, Design of Alloy Gradient Bonding Layer Parameters: A 3D model of the part is designed using 3DP technology, and the alloy gradient bonding layer parameters are designed based on slicing software. Z0: Powder: 0 vol% Alloy powder: 100 vol%, layer thickness: 0.15~0.2 mm; Z1: Powder: 20 vol%. Alloy powder: 80 vol%, layer thickness: 0.15~2 mm; Z2: Powder: 40 vol%. Alloy powder: 60 vol%, layer thickness: 0.1~0.15 mm; Z3: Powder: 50 vol%. Alloy powder: 50 vol%, layer thickness: 0.1~0.15 mm; Z4: Powder: 60 vol%. Alloy powder: 40 vol%, layer thickness: 0.1~0.15 mm; Z5: Powder: 80 vol%. Alloy powder: 20 vol%, layer thickness: 0.15~0.2 mm; Z6: Powder: 100 vol%. Alloy powder: 0 vol%, layer thickness: 0.15~0.2 mm; SB2-3, Bonding and Sintering: Following the shape and layer thickness parameters of the part's 3D drawing in SB2-2, mixed powder and binder are sprayed layer by layer. The binder is then removed by high-temperature sintering to obtain a high-temperature interface alloy component, denoted as... member; SB3. Preparation of nickel-chromium high-temperature composite alloy parts: First, in SB2-3 The components are dried at a gradient temperature and then mixed with SB1-2. The matrix is ​​bonded, and finally, nickel-chromium high-temperature composite alloy parts are obtained by vacuum hot pressing sintering at 140~160 MPa. The vacuum hot pressing sintering method in SB3 is as follows: SB3-1, SB2-3 The components are dried in an oven with the following temperature gradient: first, the temperature is raised from room temperature to 60°C within 3-4 minutes and held for 8-10 minutes; then, the temperature is raised from 60°C to 100°C within 3-5 minutes and held for 30-40 minutes; finally, the temperature is raised from 100°C to 200°C within 20-30 minutes and held for 1-1.5 hours. SB3-2, from SB1 The matrix and the substrate treated with SB3-1 The Z0 layer of the component is bonded to the surface to obtain a composite alloy billet; SB3-3. Under an external pressure of 5~10 MPa, the composite alloy billet is sintered at the following temperature gradient to obtain nickel-chromium high-temperature composite alloy parts. The temperature gradient during sintering of the composite alloy billet is as follows: first, the temperature is increased from room temperature to 700℃ at a rate of 10~12℃ / min, and held for 25~35 min; then, the temperature is increased from 700℃ to 1250℃ at a rate of 5~7℃ / min, and held for 60~70 min; finally, the temperature is decreased from 1250℃ to 800℃ at a rate of 5~7℃ / min, and held for 60~70 min.

2. The application of the nickel-chromium high-temperature master alloy as described in claim 1, characterized in that, The SB2-1 described therein Alloy powder and The method for mixing the powder in batches according to design requirements is as follows: using a star ball mill, first mix with ethanol. Alloy powder and The powder was mixed at 350-400 r / min for 24 h, and the mixed powder was freeze-dried and ground for later use. The temperature gradient for freeze drying is as follows: first, the temperature is lowered from room temperature to -30°C within 8-10 minutes and held for 5-7 minutes; then, the temperature is lowered from -30°C to -60°C within 8-10 minutes and held for 20-25 minutes; finally, the temperature is lowered from -60°C to -70°C within 4-5 minutes and held for 18-20 hours.

3. The application of the nickel-chromium high-temperature master alloy as described in claim 1, characterized in that, The components of the adhesive described in SB2-3, by volume ratio, are as follows: ethanol: 10-15%, ethylene glycol: 4-7%, phenolic resin: balance; the viscosity of the adhesive is 6.2-6.

5. The surface tension is 24~26 mN / m, and the saturation is 25~30%. The temperature gradient for removing the binder by high-temperature sintering is as follows: first, the temperature is increased from room temperature to 500℃ within 10-15 minutes and held for 20-30 minutes; then, the temperature is increased from 500℃ to 850℃ within 10-15 minutes and held for 20-30 minutes; finally, the temperature is increased from 850℃ to 1000℃ within 5-10 minutes and held for 50-60 minutes.

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