A rare earth additive for copper and copper alloys and preparation method thereof

Abstract

The invention discloses a rare earth additive for copper and copper alloy and a preparation method thereof. The rare earth additive comprises: a sealed shell and a plurality of internal alloys arranged inside the sealed shell, wherein the sealed shell contains an inert gas of a first preset pressure value; the material of the sealed shell is copper; the internal alloy comprises: rare earth metal, copper and transition metal, the content of rare earth metal is 5wt% to 95wt%, the content of copper is 5wt% to 90wt%, the content of transition metal is 0wt% to 35wt%, the oxygen content is less than 90ppm, and the average size of inclusions is less than 30μm. By introducing an inert gas of a preset pressure value, as the shell melts and becomes thinner and the gas expands due to heat, the internal intermediate alloy breaks through the shell under the positive pressure of the gas and evenly diffuses to the surroundings of the solution, which is conducive to the uniform diffusion and dissolution of the intermediate alloy, avoids the floating of the rare earth and the reaction with the atmosphere, and effectively improves the problems of poor uniformity of rare earth components, unstable control and oxidation burning.

Description

Technical Field

[0001] The present invention relates to the technical field of copper alloy manufacturing, and in particular to a rare earth additive for copper and copper alloys and a preparation method thereof. Background Art

[0002] Copper and copper alloys are widely used in electronic information, power transmission, shipbuilding and other fields due to their good electrical conductivity, thermal conductivity, corrosion resistance and processing performance. With the increasingly harsh use environment, higher requirements are placed on the performance of copper and copper alloys. Rare earth elements have strong chemical activity, variable valence and large atomic size due to their unique outer electron structure. A large number of studies and production practices at home and abroad have shown that the addition of trace rare earths can play a role in degassing and deoxidation, grain refinement, and metamorphic inclusions, thereby significantly improving the processing performance, corrosion resistance, wear resistance and electrical conductivity of copper and copper alloys.

[0003] At present, the commonly used low-density, high-activity pure rare earth or rare earth copper master alloy can only stay in the upper or middle upper part of the melt to dissolve due to the buoyancy and viscous resistance of the melt during the metallurgical addition process of copper and copper alloys, which is not only not conducive to the rapid and uniform diffusion of rare earths, but also easy to float to the surface of the melt to cause oxidation and burning, seriously affecting the normal smelting process and reducing the recovery rate and composition uniformity of rare earths, restricting the metallurgical addition and use of rare earths. In addition, the commonly used rare earth metals or rare earth copper master alloys are very easy to oxidize, which is not only not conducive to the storage of rare earth additives, but also the rare earth oxide inclusions introduced by them will seriously damage the performance of the base metal. Summary of the invention

[0004] The purpose of the embodiment of the present invention is to provide a rare earth additive for copper and copper alloys and a preparation method thereof. By introducing an inert gas with a preset pressure value, as the shell melts and becomes thinner and the gas expands due to heat, the internal intermediate alloy breaks through the outer shell under the positive pressure of the gas and diffuses evenly around the solution, which is not only conducive to the uniform diffusion and dissolution of the intermediate alloy, but also can avoid the rare earth from floating up and reacting with the atmosphere, and effectively improves the problems of poor composition uniformity, unstable control and oxidation burning of the rare earth during the addition process.

[0005] In order to solve the above technical problems, a first aspect of an embodiment of the present invention provides a rare earth additive for copper and copper alloys, comprising: a sealed shell and a plurality of internal alloys arranged inside the sealed shell, wherein nitrogen or an inert gas with a first preset pressure value is contained inside the sealed shell;

[0006] The material of the sealing shell is copper;

[0007] The internal alloy includes rare earth metals, copper and transition metals, the rare earth metal content is 5wt% to 95wt%, the copper content is 5wt% to 90wt%, the transition metal content is 0wt% to 35wt%, the oxygen content is less than 90ppm, and the average size of inclusions is less than 30μm.

[0008] Furthermore, the first preset pressure value of the inert gas is 0.05MPa to 0.6MPa;

[0009] Preferably, the first preset pressure value is 0.15 MPa to 0.5 MPa.

[0010] Furthermore, a ratio value of the sum of the volumes of the plurality of internal alloys to the internal volume of the sealed housing is greater than a preset ratio value;

[0011] Preferably, the preset ratio value is 70%;

[0012] Further preferably, the preset ratio value is 80%.

[0013] Further, the inert gas includes at least one of argon, nitrogen, helium, neon, krypton, radon and xenon;

[0014] Preferably, the inert gas is argon.

[0015] Furthermore, the thickness of the sealed shell is 2 mm to 60 mm, the purity is greater than 99.97%, and the oxygen content is less than 30 ppm;

[0016] Preferably, the thickness of the sealing shell is 5 mm to 25 mm.

[0017] Furthermore, one end of the sealing shell is streamlined with an attack angle, and the attack angle is the angle between the center point of the end of the sealing shell and the line connecting two edge points of the streamlined axial section away from the end;

[0018] Optionally, the streamline shape includes: a parabola, a sphere or a cone;

[0019] The numerical range of the attack angle is 25° to 165°.

[0020] Furthermore, the aspect ratio of the sealed housing is 1 to 5;

[0021] The length of the sealing shell ranges from 60 mm to 500 mm.

[0022] Furthermore, the content of the rare earth metal is 20wt% to 60wt%, the content of the copper is 20wt% to 60wt%, the content of the transition metal is 5wt% to 20wt%, the oxygen content is less than 60ppm, and the inclusion particle size is less than 20μm.

[0023] Further, the rare earth metal includes at least one of lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, yttrium and scandium, and the transition metal includes at least one of nickel, chromium, zirconium, cobalt, zinc, tin, lead, silver, beryllium, silicon, aluminum, iron, titanium, boron and tungsten;

[0024] Preferably, the rare earth metal includes at least one of lanthanum, cerium, praseodymium, yttrium and europium.

[0025] Furthermore, the shape of the internal alloy includes at least one of granular, block, powder, filament or irregular shape.

[0026] Accordingly, a second aspect of an embodiment of the present invention provides a method for preparing a rare earth additive for copper and copper alloys, which is used to prepare the rare earth additive for copper and copper alloys, and comprises the following steps:

[0027] Adding rare earth metals, copper and transition metals to a vacuum medium frequency reactor in a predetermined ratio, filling the vacuum medium frequency reactor with inert gas and maintaining a second preset pressure value, gradually increasing the heating temperature until the metal in the vacuum medium frequency reactor is melted and maintaining the temperature at a preset temperature for a preset time, and then gradually cooling the temperature to obtain an internal alloy;

[0028] The internal alloy is placed in a prefabricated shell, the air in the prefabricated shell is evacuated, an inert gas is filled in and a first preset pressure value is maintained, and the prefabricated shell is sealed to obtain a rare earth copper master alloy.

[0029] Furthermore, after obtaining the internal alloy, the process further comprises:

[0030] The internal alloy is crushed and screened to obtain internal alloy particles with a particle size of 15 mm to 70 mm.

[0031] Further, the value of the preset temperature is 1200°C to 1700°C;

[0032] The value of the preset time length is 5 minutes to 40 minutes.

[0033] The above technical solution of the embodiment of the present invention has the following beneficial technical effects:

[0034] 1. By introducing an inert gas with a preset pressure value, as the shell melts and becomes thinner and the gas expands due to heat, the internal master alloy breaks through the shell under the positive pressure of the gas and diffuses evenly around the solution, which is not only conducive to the uniform diffusion and dissolution of the master alloy, but also prevents the rare earth from floating up and reacting with the atmosphere, effectively improving the poor uniformity of the rare earth composition, unstable control and oxidation burning during the rare earth addition process;

[0035] 2. By adopting the streamlined structure of the shell attack angle, the additive can quickly pass through the surface of the melt and enter the middle or lower middle part when added to the melt, avoiding the problem of oxidation and burning caused by the additive floating on the surface of the melt;

[0036] 3. The design of the closed outer shell can prevent the internal rare earth metal or rare earth copper master alloy from contacting with oxygen, effectively solving the oxidation problem of rare earth in the additive during storage and use;

[0037] 4. Through the regulation of components and proportions, additives can achieve the precise addition of rare earths and multiple components such as nickel, chromium, zirconium, silver, etc. in various copper and copper alloys such as silver-copper alloy, beryllium-copper alloy, nickel-copper alloy, and optimize the alloy batching process. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a schematic diagram of the structure of a rare earth additive for copper and copper alloys provided in an embodiment of the present invention.

[0039] Reference numerals:

[0040] 1. Nitrogen or inert gas, 2. Internal alloy, 3. Shell. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings. It should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present invention. In addition, in the following description, the description of well-known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present invention.

[0042] Please refer to Figure 1 A first aspect of an embodiment of the present invention provides a rare earth additive for copper and copper alloys, comprising: a sealed shell 3 and a plurality of internal alloys 2 arranged inside the sealed shell 3, wherein the sealed shell 3 contains nitrogen or an inert gas 1 with a first preset pressure value; the sealed shell 3 is made of copper; the internal alloy 2 comprises: rare earth metals, copper and transition metals, the rare earth metal content is 5wt% to 95wt%, the copper content is 5wt% to 90wt%, the transition metal content is 0wt% to 35wt%, the oxygen content is less than 90ppm, and the average size of inclusions is less than 30μm.

[0043] Specifically, the first preset pressure value of the inert gas 1 is 0.05MPa-0.6MPa; preferably, the first preset pressure value is 0.15MPa-0.5MPa. The selection of the filling pressure of the inert gas 1 is based on a comprehensive analysis and design of the melt pressure, melt temperature, and internal gas expansion impact force, which not only ensures that the internal metal can break through the external shell and diffuse to the surrounding of the melt after the additive sinks into the middle or lower part of the melt, but also ensures that the internal gas pressure is controllable so as not to cause excessive mechanical vibration and melt splashing.

[0044] Further, the inert gas 1 includes at least one of argon, nitrogen, helium, neon, krypton, radon, and xenon; preferably, the inert gas 1 is argon. Preferably, argon is an inert gas 1 commonly used in the metallurgical industry, which is insoluble in liquid metal and does not react with the melt at high temperatures, and is relatively inexpensive compared to inert gases 1 such as helium, neon, krypton, radon, and xenon, and is suitable for industrial production. In addition, the present invention can minimize the introduction of oxygen by strictly controlling the purity of argon.

[0045] Specifically, the shape of the internal alloy 2 includes at least one of granular, block, powder, filament or irregular shape. Further, the ratio of the sum of the volumes of the plurality of internal alloys 2 to the internal volume of the sealed housing 3 is greater than a preset ratio; preferably, the preset ratio is 70%; further preferably, the preset ratio is 80%. A larger proportion of metal in the housing can ensure the quality of the overall additive, which is conducive to the additive sinking in the middle and lower part of the melt, and ensures the uniform diffusion and dissolution of the metal.

[0046] Optionally, the content of rare earth metal is 20wt% to 60wt%, the content of copper is 20wt% to 60wt%, the content of transition metal is 5wt% to 20wt%, the oxygen content is less than 60ppm, and the particle size of inclusions is less than 20μm.

[0047] Furthermore, the rare earth metal includes at least one of lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, yttrium and scandium, and the transition metal includes at least one of nickel, chromium, zirconium, cobalt, zinc, tin, lead, silver, beryllium, silicon, aluminum, iron, titanium, boron and tungsten. Transition metals are commonly used alloying elements in different types of copper alloys, so the rare earth and other alloying elements can be added at one time by adjusting the ratio of additive components.

[0048] Preferably, the rare earth metal includes at least one of lanthanum, cerium, praseodymium, yttrium and europium. Preferably, the rare earth metal is light rare earth with abundant reserves, high distribution, slow-moving and cheap prices in my country, and yttrium and europium, which are commonly used rare earth metals for copper and copper alloys, which can not only promote the efficient and comprehensive balanced utilization of rare earth resources, but also help improve the performance of copper and copper alloys.

[0049] The shape of the shell includes but is not limited to a cuboid, a cube, a cone, a sphere, a cylinder, a shuttle shape, and a streamline shape.

[0050] Specifically, in a specific implementation of the embodiment of the present invention, one end of the sealing housing 3 is streamlined with an attack angle; optionally, the streamline includes: parabola, sphere or cone; the value range of the attack angle is 25° to 165°, the overall aspect ratio (length-to-diameter ratio) is 1 to 5, and the length L ranges from 60 to 500 mm. Specifically, the above-mentioned attack angle is the angle between the center point of the end of the sealing housing 3 and the line connecting the two edge points of the streamlined axial section away from the end.

[0051] The preferred streamlined attack angle, aspect ratio (length-to-diameter ratio), and overall length range are designed based on a comprehensive analysis of the viscous resistance of copper and copper alloy melts, the specific gravity of additives, process addition conditions, etc. The streamlined additive with an attack angle has a lower resistance coefficient and can sink to the middle or lower middle part of the melt after addition, and the intermediate alloy can be evenly diffused around the solution under the positive pressure of the internal gas, while effectively avoiding the oxidation burning problem caused by the floating of rare earth additives.

[0052] Further, the thickness of the sealed shell 3 is 2 mm to 60 mm, the purity is greater than 99.97%, and the oxygen content is less than 30 ppm; preferably, the thickness of the sealed shell 3 is 5 mm to 25 mm. Based on a comprehensive analysis of the alloying addition process of copper and copper alloys, melt temperature, shell protection, etc., the thickness of the shell is designed to be 2 mm to 60 mm, preferably 5 mm to 25 mm, which ensures that the protective shell will not be easily broken during storage and addition, effectively isolates the internal rare earth metal from external oxygen, and controls the time for it to be melted and broken after addition, ensuring that it is effectively sunk into the middle or lower middle part of the melt after addition before being melted and broken, so that the internal rare earth copper intermediate alloy is evenly diffused around the solution.

[0053] Accordingly, a second aspect of an embodiment of the present invention provides a method for preparing a rare earth additive for copper and copper alloys, which is used to prepare the rare earth additive for copper and copper alloys, and comprises the following steps:

[0054] Step S100, selecting an oxygen-free copper plate of appropriate specifications to prepare a shell layer with a specific external shape.

[0055] Step S200, prepare the ingredients according to the composition requirements of the inner layer metal of the additive and put the rare earth metal, copper and transition metal raw materials into the crucible of the vacuum medium frequency induction furnace; close the furnace cover and evacuate to 0.1Pa, then fill in 60000Pa~80000Pa high-purity argon and repeat the furnace cleaning 3 times; bake the furnace at low power for 10 minutes, then fill in argon to maintain the vacuum in the furnace at 50000Pa~80000Pa, then slowly increase the power step by step to completely melt the metal in the furnace; after the metal in the crucible is completely melted, refine and keep warm for 10min~20min; after reducing the power step by step, pour the solution into a mold with a pre-designed shape; cool with the furnace under the protection of the furnace atmosphere, demold to obtain the rare earth copper intermediate alloy.

[0056] The rare earth copper master alloy prepared above is crushed by using a crushing device under the protection of an inert gas 1, and then the rare earth copper master alloy particles are sieved by using a vibrating screen, and the particle size is 15 mm to 70 mm.

[0057] Specifically, the rare earth metal in the raw material can be prepared by metal thermal reduction or molten salt electrolysis; in addition, the rare earth, copper and transition metal can be RE-Cu or RE-M intermediate alloys directly prepared by molten salt electrolysis. In the raw materials: the purity of copper and metal M is ≥99.5%, and the oxygen content is <30ppm; the purity of rare earth metal RE is ≥99.9%, and the oxygen content is <100ppm. The crucible is an aluminum oxide crucible, a magnesium oxide crucible or a calcium oxide crucible. The selected crucible has stable quality and long service life, which can ensure the purity of the produced alloy.

[0058] Step S300, placing the internal alloy 2 in the prefabricated shell 3, filling with the inert gas 1 and maintaining a first preset pressure value, sealing the prefabricated shell 3, and obtaining a rare earth copper master alloy.

[0059] The internal metal prepared in step S200 is placed in the shell structure prepared in step 1, and the internal metal occupies ≥70% of the cavity volume. After the air in the metal shell is emptied, the inert gas 1 is filled in. When the internal gas pressure is greater than 0.1MPa~0.6MPa, the ventilation is stopped, and then the inflation port is sealed by welding or melt bonding.

[0060] The above preparation method is described in detail below with reference to several comparative examples and embodiments:

[0061] Example 1

[0062] A method for preparing a Ce-Cu-Ni master alloy of the present invention comprises the following steps:

[0063] The external shell of the additive is prepared using a 2 mm thick oxygen-free copper plate, the attack angle α at the front end of the shell is 53°, and the shape at the attack angle is parabolic.

[0064] Prepare materials according to the weight percentage of each component of the alloy: electrolytic nickel, electrolytic copper, and rare earth metal cerium obtained by metal thermal reduction are 10%, 60%, and 30%, respectively. Among them, the purity of electrolytic nickel and electrolytic copper raw materials is 99.5%, and the purity of rare earth metal cerium is 99.9%. Put the electrolytic nickel and electrolytic copper raw materials into the alumina crucible of the vacuum induction melting furnace, and put the rare earth metal cerium into the trough of the vacuum induction melting furnace. After evacuating the vacuum degree in the melting furnace to below 0.1Pa, high-purity argon is filled in to make the vacuum degree in the furnace reach 80000Pa. After repeating the furnace washing 3 times, bake the furnace at low power for 5min and then fill it with high-purity argon to 60000Pa, then slowly increase the power until the copper and nickel blocks in the furnace are completely melted, and then add rare earth metal cerium to the molten metal through the trough and refine and keep warm for 10min. After the refining is completed, the power is gradually reduced and the alloy solution is poured into the mold. The alloy was cooled in the furnace under the protection of argon atmosphere, and demolded after 2 hours to obtain 49.8 kg of Ce-Cu-Ni master alloy. The mold can be a cast iron mold or a stainless steel mold. After analysis, the alloy ingot inclusions averaged 26 μm and the oxygen content was 85 ppm.

[0065] The Ce-Cu-Ni master alloy prepared by the above melting method is crushed by crushing equipment under the protection of inert gas, and then the rare earth copper master alloy particles are screened by a vibrating screen, and the particle size is 20-60mm. Then the alloy particles are loaded into the shell, the rare earth alloy filling ratio is 80%, and the air in the metal shell is emptied and filled with high-purity argon gas. When the internal gas pressure reaches 0.05MPa, the ventilation is stopped, and then the air inlet is sealed by welding or melt bonding. The final shell has an overall length of 360mm and a diameter of 180mm.

[0066] Example 2

[0067] A method for preparing a La-Y-Cu-Cr master alloy of the present invention comprises the following steps:

[0068] The external shell of the additive is prepared using a 5 mm thick oxygen-free copper plate, the attack angle α at the front end of the shell is 90°, and the shape at the attack angle is conical.

[0069] Prepare materials according to the weight percentage of each component of the alloy: electrolytic chromium, electrolytic copper, rare earth metal lanthanum and yttrium obtained by metal thermal reduction are 5%, 55%, 35% and 5% respectively. Among them, the purity of electrolytic chromium and electrolytic copper raw materials is 99.5%, and the purity of rare earth metal lanthanum and yttrium is 99.9%. Put the electrolytic chromium and electrolytic copper raw materials into the alumina crucible of the vacuum induction melting furnace, and put the rare earth metal lanthanum and yttrium into the trough of the vacuum induction melting furnace. After evacuating the smelting furnace to a vacuum degree of less than 0.1Pa, high-purity argon is filled in to make the vacuum degree in the furnace reach 80000Pa. After repeating the furnace washing 3 times, bake the furnace at low power for 5min and then fill it with high-purity argon to 60000Pa, then slowly increase the power until the copper and chromium blocks in the furnace are completely melted, and then add rare earth metal lanthanum and yttrium to the molten metal through the trough and refine and keep warm for 10min. After refining, the power is gradually reduced and the alloy solution is poured into the mold. It is cooled in the furnace under the protection of argon atmosphere in the furnace. After 2 hours, the mold is demolded to obtain 25.3kg of La-Y-Cu-Cr master alloy. The mold can be a cast iron mold or a stainless steel mold. After analysis, the average inclusions of the alloy ingot are 25μm and the oxygen content is 79ppm.

[0070] The La-Y-Cu-Cr master alloy prepared by the above-mentioned melting method is crushed by crushing equipment under the protection of inert gas, and then the rare earth copper master alloy particles are screened by a vibrating screen, and the particle size is 20-60 mm. Then the alloy particles are loaded into the shell, and the rare earth alloy filling ratio is 85%. After the air in the metal shell is emptied, high-purity argon gas is filled in. When the internal gas pressure reaches 0.25MPa, the ventilation is stopped, and then the air inlet is sealed by welding or melt bonding. The final shell has an overall length of 420mm and a diameter of 280mm.

[0071] Example 3

[0072] A method for preparing a Fe-Cu-Pr master alloy of the present invention comprises the following steps:

[0073] The external shell of the additive is prepared using a 4 mm thick oxygen-free copper plate, the attack angle α at the front end of the shell is 45°, and the shape at the attack angle is spherical.

[0074] Prepare materials according to the weight percentage of each component of the alloy: electrolytic copper, rare earth Pr, and iron are 40%, 34%, and 26% respectively. Among them, the purity of electrolytic copper is 99.5%, and iron and rare earth metal praseodymium are Fe-Pr alloys directly prepared by molten salt electrolysis, with a purity of 99.9%. Put the Fe-Pr alloy and electrolytic copper raw materials into the alumina crucible of the vacuum induction melting furnace, evacuate until the vacuum degree in the melting furnace is below 0.1Pa, and then fill with high-purity argon gas to make the vacuum degree in the furnace reach 80000Pa. After repeating the furnace washing 3 times, bake the furnace at low power for 5min, then fill with high-purity argon gas to 60000Pa, and then slowly increase the power until the metal in the furnace is completely melted, and then refine and keep warm for 10min. After the refining is completed, gradually reduce the power and pour the alloy solution into the mold. Cool with the furnace under the protection of argon atmosphere in the furnace, and demold after 2h to obtain 50kg of Fe-Cu-Pr intermediate alloy. The mold can be a cast iron mold or a stainless steel mold. According to analysis, the alloy ingot inclusions are 15 μm on average and the oxygen content is 50 ppm.

[0075] The Fe-Cu-Pr master alloy prepared by the above-mentioned melting method is crushed by crushing equipment under the protection of inert gas, and then the rare earth copper master alloy particles are screened by a vibrating screen, and the particle size is 15-60mm. Then the alloy particles are loaded into the shell, the rare earth alloy filling ratio is 85%, and the air in the metal shell is emptied and filled with 80% Ar+20% N2. When the internal gas pressure reaches 0.2MPa, the ventilation is stopped, and then the air inlet is sealed by welding or melt bonding. The final shell has an overall length of 60mm and a diameter of 20mm.

[0076] Comparative Example 1

[0077] A method for preparing a Ce-Cu-Ni master alloy of the present invention comprises the following steps:

[0078] The external shell of the additive is prepared using a 2 mm thick oxygen-free copper plate, the attack angle α at the front end of the shell is 53°, and the shape at the attack angle is parabolic.

[0079] Prepare materials according to the weight percentage of each component of the alloy: electrolytic nickel, electrolytic copper, and rare earth metal cerium obtained by metal thermal reduction are 10%, 60%, and 30%, respectively. Among them, the purity of electrolytic nickel and electrolytic copper raw materials is 99.5%, and the purity of rare earth metal cerium is 99.9%. Put the electrolytic nickel and electrolytic copper raw materials into the alumina crucible of the vacuum induction melting furnace, and put the rare earth metal cerium into the trough of the vacuum induction melting furnace. After evacuating the vacuum degree in the melting furnace to below 0.1Pa, high-purity argon is filled in to make the vacuum degree in the furnace reach 80000Pa. After repeating the furnace washing 3 times, bake the furnace at low power for 5min and then fill it with high-purity argon to 60000Pa, then slowly increase the power until the copper and nickel blocks in the furnace are completely melted, and then add rare earth metal cerium to the molten metal through the trough and refine and keep warm for 10min. After the refining is completed, the power is gradually reduced and the alloy solution is poured into the mold. The alloy was cooled in the furnace under the protection of argon atmosphere, and demolded after 2 hours to obtain 50.2 kg of Ce-Cu-Ni master alloy. The mold can be a cast iron mold or a stainless steel mold. After analysis, the alloy ingot inclusions averaged 26 μm and the oxygen content was 85 ppm.

[0080] The Ce-Cu-Ni master alloy prepared by the above-mentioned melting method is crushed by a crushing device under the protection of inert gas, and then the rare earth copper master alloy particles are screened by a vibrating screen, and the particle size is 20-60 mm. Subsequently, the alloy particles are loaded into the shell, and the rare earth alloy filling ratio is 80%. The final shell has an overall length of 360 mm and a diameter of 180 mm.

[0081] Comparative Example 2

[0082] A method for preparing a Ce-Cu-Ni master alloy of the present invention comprises the following steps:

[0083] Prepare materials according to the weight percentage of each component of the alloy: electrolytic nickel, electrolytic copper, and rare earth metal cerium obtained by metal thermal reduction are 10%, 60%, and 30%, respectively. Among them, the purity of electrolytic nickel and electrolytic copper raw materials is 99.5%, and the purity of rare earth metal cerium is 99.9%. Put the electrolytic nickel and electrolytic copper raw materials into the alumina crucible of the vacuum induction melting furnace, and put the rare earth metal cerium into the trough of the vacuum induction melting furnace. After evacuating the vacuum degree in the melting furnace to below 0.1Pa, high-purity argon is filled in to make the vacuum degree in the furnace reach 80000Pa. After repeating the furnace washing 3 times, bake the furnace at low power for 5min and then fill it with high-purity argon to 60000Pa, then slowly increase the power until the copper and nickel blocks in the furnace are completely melted, and then add rare earth metal cerium to the molten metal through the trough and refine and keep warm for 10min. After the refining is completed, the power is gradually reduced and the alloy solution is poured into the mold. The alloy was cooled in the furnace under the protection of argon atmosphere, and demolded after 2 hours to obtain 49.6 kg of Ce-Cu-Ni master alloy. The mold can be a cast iron mold or a stainless steel mold. After analysis, the alloy ingot inclusions averaged 26 μm and the oxygen content was 85 ppm.

[0084] In order to further verify and illustrate the beneficial effects of the rare earth additive, a comparative test of rare earth addition was carried out in copper alloy.

[0085] Comparative test 1

[0086] Example 1, Comparative Example 1, Comparative Example 2 and single rare earth Ce and Ni were used to perform rare earth alloying addition in the T15400 copper alloy process production line, wherein the theoretical addition amount of rare earth was 200ppm. The yield rate, composition uniformity and inclusion size of the rare earth in each copper alloy sample are shown in Table 1 (yield rate, uniformity and average inclusion size of rare earth in T15400 copper alloy). It can be found that after the addition of the intermediate alloy of Example 1, the composition uniformity and rare earth yield rate of the rare earth in the copper alloy are much better than the effect of using single rare earth, Comparative Example 1 (no gas filling) and Comparative Example 2 (no streamlined shell, no gas) as additives. This is because in the process of adding, the shell surface of Example 1 can sink quickly to the middle or lower middle part of the melt due to the lower resistance coefficient. At the same time, as the shell melts and becomes thinner and the gas expands due to heat, the internal master alloy breaks through the shell under positive pressure and diffuses evenly around the solution, which is not only conducive to the uniform diffusion of the master alloy in the melt, but also avoids the floating of rare earth and the reaction with the atmosphere, effectively improving the problem of poor composition uniformity and oxidation burning of rare earth during the addition process. At the same time, through the control of raw material purity and strict control of smelting system, operating atmosphere, etc. during the preparation process such as melting and coating, the average size of inclusions in the copper alloy after the rare earth additive is added is controlled to be less than 10μm, which is better than the addition effect of other rare earth additives. In addition, the Ce-Cu-Ni master alloy also realizes the one-time precise addition of rare earth and nickel.

[0087] Table 1

[0088]

[0089]

[0090] Comparative test 2

[0091] Example 2, Comparative Example 3, Comparative Example 4 and single rare earth La, Y, Cr were used to add rare earth alloys in the T19460 copper alloy process production line, wherein the theoretical addition amount of rare earth was 200ppm. The yield rate, composition uniformity, and inclusion size of rare earth in each sample are shown in Table 2 (yield rate, uniformity, and average size of inclusions of rare earth in T19460 copper alloy). It can be found that after adding Example 1, the composition uniformity and rare earth yield rate of rare earth in the copper alloy are much better than the effect of using single rare earth, Comparative Example 1 (no gas filling) and Comparative Example 2 (no streamlined shell and gas) as rare earth additives. At the same time, by controlling the purity of the raw materials and strictly controlling the smelting system, operating atmosphere, etc. during the preparation process such as melting and coating, the average size of inclusions in the copper alloy after the additive is added is controlled to be less than 10μm, which is better than the addition effect of other rare earth additives. In addition, the La-Y-Cu-Cr master alloy also realizes the one-time precise addition of rare earth and chromium.

[0092] Table 2

[0093]

[0094] The invention prepares gas-containing rare earth additives for different types of copper and copper alloys through experiments, and detects and analyzes the oxygen content, oxidation resistance and average size of inclusions of the additives.

[0095] Specifically, in the alloy oxidation weight gain test, each intermediate alloy is first processed into an oxidation sample with a size of φ15mm×30mm by wire cutting, 5 samples are prepared in each group, and they are polished with SiC sandpaper of No. 240 to 2000 in turn, and then ultrasonically cleaned with acetone and alcohol, placed in a drying oven for insulation for 1 hour, and then taken out and placed in a dryer to cool to room temperature and then weighed; then the test corundum crucible is roasted and dried until constant weight; then a high-temperature oxidation resistance test is carried out in a high-temperature furnace, and the sample is loaded into the furnace after the furnace temperature is raised to 1000°C, and a static weight gain method is used to select oxidation tests in an air medium, and the crucible is taken out from the furnace every 20 hours of insulation, and weighed after cooling to room temperature, and the cumulative oxidation time is 100 hours.

[0096] A 10×10×10 sample was further cut from the prepared additive, and the sample was pre-ground and polished, and then a scanning electron microscope (SEM) was used to observe and count the size and distribution of the inclusions.

[0097] From the physical property parameters of each embodiment and comparative example in Table 3, it can be seen that the present invention can prevent rare earth metal or rare earth copper master alloy from contacting with external oxygen by introducing a closed shell layer, and effectively slow down the oxidation problem of rare earth during storage and use. The oxidation weight gain test shows that the oxidation resistance of the intermediate alloy in the embodiment is better than the oxidation resistance of the same series of rare earth additives without a shell in the comparative example. For example, under the effective closed isolation effect of the external shell layer, the oxidation weight gain rate of the Ce-Cu-Ni master alloy in Example 1 is only 0.203g / m2h, while the oxidation weight gain rate of the Ce-Cu-Ni master alloy without shell coating in Comparative Example 2 is as high as 0.327g / m2h. Under the effective closed isolation effect of the external shell layer, the oxidation weight gain rate of the La-Y-Cu-Cr master alloy in Example 2 is only 0.212g / m2h, while the oxidation weight gain rate of the La-Y-Cu-Cr master alloy without shell coating in Comparative Example 4 is as high as 0.295g / m2h.

[0098] At the same time, by controlling the purity of the raw materials and strictly controlling the smelting system, operating atmosphere, etc. during the preparation processes such as melting and coating, the oxygen content of the high-density rare earth additive can be controlled below 90 ppm, and the size of the inclusions can be controlled below 30 μm, thereby effectively controlling the adverse effects of large-sized rare earth inclusions on the properties of copper and copper alloys.

[0099] Table 3

[0100]

[0101]

[0102]

[0103]

[0104]

[0105] The embodiment of the present invention aims to protect a rare earth additive for copper and copper alloys and a preparation method thereof, wherein the rare earth additive comprises: a sealed shell and a plurality of internal alloys arranged inside the sealed shell, wherein the sealed shell contains an inert gas of a first preset pressure value; the material of the sealed shell is copper; the internal alloy comprises: rare earth metals, copper and transition metals, wherein the content of rare earth metals is 5wt% to 95wt%, the content of copper is 5wt% to 90wt%, the content of transition metals is 0wt% to 35wt%, the oxygen content is less than 90ppm, and the average size of inclusions is less than 30μm. The above technical solution has the following effects:

[0106] 1. By introducing an inert gas with a preset pressure value, as the shell melts and becomes thinner and the gas expands due to heat, the internal master alloy breaks through the shell under the positive pressure of the gas and diffuses evenly around the solution, which is not only conducive to the uniform diffusion and dissolution of the master alloy, but also prevents the rare earth from floating up and reacting with the atmosphere, effectively improving the poor uniformity of the rare earth composition, unstable control and oxidation burning during the rare earth addition process;

[0107] 2. By adopting the streamlined structure of the shell attack angle, the additive can quickly pass through the surface of the melt and enter the middle or lower middle part when added to the melt, avoiding the problem of oxidation and burning caused by the additive floating on the surface of the melt;

[0108] 3. The design of the closed outer shell can prevent the internal rare earth metal or rare earth copper master alloy from contacting with oxygen, effectively solving the oxidation problem of rare earth in the additive during storage and use;

[0109] 4. Through the regulation of components and proportions, additives can achieve the precise addition of rare earths and multiple components such as nickel, chromium, zirconium, silver, etc. in various copper and copper alloys such as silver-copper alloy, beryllium-copper alloy, nickel-copper alloy, and optimize the alloy batching process.

[0110] It should be understood that the above specific embodiments of the present invention are only used to illustrate or explain the principles of the present invention, and do not constitute a limitation of the present invention. Therefore, any modifications, equivalent substitutions, improvements, etc. made without departing from the spirit and scope of the present invention should be included in the protection scope of the present invention. In addition, the appended claims of the present invention are intended to cover all changes and modifications that fall within the scope and boundaries of the appended claims, or the equivalent forms of such scope and boundaries.

Claims

1. A rare earth additive for copper and copper alloys, characterized in that: include: A sealed shell and a plurality of internal alloys arranged inside the sealed shell, wherein the sealed shell contains nitrogen or an inert gas with a first preset pressure value; The material of the sealing shell is copper; The internal alloy consists of rare earth metals, copper and other transition metals except rare earth metals and copper, 5 wt%≤the content of the rare earth metals≤95 wt%, 5wt%≤the content of the copper≤90 wt%, 0 wt%<the content of other transition metals except rare earth metals and copper≤35 wt%, the oxygen content is less than 90 ppmw, and the average size of inclusions is less than 30 μm.

2. The rare earth additive for copper and copper alloys according to claim 1, characterized in that: The first preset pressure value of the inert gas is 0.05 MPa to 0.6 MPa.

3. The rare earth additive for copper and copper alloys according to claim 2, characterized in that: The first preset pressure value is 0.15 MPa to 0.5 MPa.

4. The rare earth additive for copper and copper alloys according to claim 1, characterized in that: The ratio of the sum of the volumes of the plurality of internal alloys to the internal volume of the sealed housing is greater than a preset ratio, which is 70% or 80%.

5. The rare earth additive for copper and copper alloys according to claim 1, characterized in that: The inert gas includes at least one of argon, helium, neon, krypton, radon and xenon.

6. The rare earth additive for copper and copper alloys according to claim 5, characterized in that: The inert gas is argon.

7. The rare earth additive for copper and copper alloys according to claim 1, characterized in that: The sealed shell has a thickness of 2 mm to 60 mm, a purity greater than 99.97%, and an oxygen content less than 30 ppmw.

8. The rare earth additive for copper and copper alloys according to claim 7, characterized in that: The thickness of the sealing shell is 5 mm to 25 mm.

9. The rare earth additive for copper and copper alloys according to claim 1, characterized in that: The sealed shell is in the shape of a cuboid, a cube, a cone, a sphere or a cylinder.

10. The rare earth additive for copper and copper alloys according to claim 1, characterized in that: One end of the sealing shell is streamlined with an attack angle, wherein the attack angle is the angle between the center point of the end of the sealing shell and the line connecting two edge points of the streamlined axial section away from the end; The numerical range of the attack angle is 25° to 165°.

11. The rare earth additive for copper and copper alloys according to claim 10, characterized in that: The aspect ratio of the sealing shell is 1 to 5; The length of the sealing shell ranges from 60 mm to 500 mm.

12. The rare earth additive for copper and copper alloys according to any one of claims 1 to 11, characterized in that: 20wt%≤the rare earth metal content≤60wt%, 20wt%≤the copper content≤60 wt%, 5wt%≤the content of other transition metals except rare earth metals and copper≤20wt%, oxygen content<60ppmw, and inclusion particle size is less than 20μm.

13. The rare earth additive for copper and copper alloys according to claim 12, characterized in that: The rare earth metal includes: at least one of lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, yttrium and scandium; the other transition metals except rare earth metals and copper include: at least one of nickel, chromium, zirconium, cobalt, silver, iron, titanium and tungsten.

14. The rare earth additive for copper and copper alloys according to claim 13, characterized in that: The rare earth metal includes at least one of lanthanum, cerium, praseodymium, yttrium and europium.

15. The rare earth additive for copper and copper alloys according to any one of claims 1 to 11, characterized in that: The shape of the internal alloy includes at least one of granular, blocky, wire-like or irregular shapes.

16. A method for preparing a rare earth additive for copper and copper alloys, characterized in that: The method for preparing the rare earth additive for copper and copper alloys as claimed in any one of claims 1 to 15 comprises the following steps: Adding rare earth metals, copper and other transition metals except rare earth metals and copper into a vacuum medium frequency reactor according to a predetermined ratio, filling the vacuum medium frequency reactor with inert gas and maintaining a second preset pressure value, gradually increasing the heating temperature until the metal in the vacuum medium frequency reactor is melted and maintaining the temperature at a preset temperature for a preset time, and then gradually cooling the temperature to obtain an internal alloy; The internal alloy is placed in a prefabricated shell, the air in the prefabricated shell is evacuated, an inert gas is filled in and a first preset pressure value is maintained, and the prefabricated shell is sealed to obtain a rare earth copper master alloy.

17. The method for preparing rare earth additives for copper and copper alloys according to claim 16, characterized in that: After obtaining the internal alloy, the method further comprises: The internal alloy is crushed and screened to obtain internal alloy particles with a particle size of 15 mm to 70 mm.

18. The method for preparing rare earth additives for copper and copper alloys according to claim 16, characterized in that: The value of the preset temperature is 1200°C to 1700°C; The value of the preset time length is 5 minutes to 40 minutes.

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