CN115388652A - Crucible assembly for induction furnace and preparation method thereof - Google Patents

Abstract

The invention discloses a crucible assembly for an induction furnace and a preparation method thereof, wherein the induction furnace is used for smelting metal and comprises a furnace body, an induction coil is arranged in the furnace body, a crucible assembly can be arranged in the induction coil, the crucible assembly comprises a crucible assembly body and a sealing body arranged at the upper part of the crucible assembly body, the crucible assembly body comprises a cavity for containing raw materials, and the top end of the cavity is opened; the crucible assembly can realize the separation of the contact of a smelting high-temperature raw material and an induction coil, avoid short circuit or furnace explosion, effectively avoid the defects of surface white spots, white lines and the like caused by impurities mixed in a smelting process product, and effectively improve the safety, yield and production efficiency of smelting silver or silver alloy.

Description

Crucible component for induction furnace and preparation method thereof

technical field

The invention belongs to the technical field of metal smelting, and in particular relates to a crucible assembly for an induction furnace and a preparation method thereof.

Background technique

Silver and silver alloys are the most widely used precious metal materials, mainly used in aerospace and electronic industry as electrical contact materials for precision instruments and precious metal jewelry materials.

At present, the preparation of silver and silver alloy ingots usually uses an induction melting furnace for vacuum melting. The crucible for melting is generally made of alumina crucible, and the material for the filling layer between the alumina crucible and the induction coil is generally made of alumina coarse sand, fine sand and oxide Aluminum powder, the filling layer is used to connect the alumina crucible and the induction coil, and fix the alumina crucible in the induction coil. The purpose of selecting alumina fine sand and alumina powder is to fill the gap between alumina coarse sand and prevent large voids in the filling layer of alumina coarse sand only during the vibration process of induction melting. If the alumina crucible cracks during the smelting process, large cracks are formed, and the high-temperature molten metal flows into the filling layer, contacts the induction coil through the cavity, and connects the induction coil to cause a short circuit or even destroy the induction coil, contacting the cooling water in the induction coil, A large amount of water vapor is formed, causing serious accidents such as furnace explosion.

During continuous induction smelting of silver and silver alloys, the crucible will crack due to multiple thermal expansions and contractions and vibrations. If more than 5 furnaces of silver and silver alloy ingots are melted, small cracks will form in the crucible, and fine alumina powder will flow from the filling. layer into the silver and silver alloy liquid; when there are too many cracks, under the impact of high-temperature melt, small crucible pieces will fall off from the crucible, causing serious damage to the crucible, resulting in the phenomenon of "porcelain falling off" in the crucible. The alumina fine sand or even alumina coarse sand in the filling layer will enter the silver and silver alloy liquid. When silver and silver alloy liquid are cast into ingots, alumina fine sand and coarse sand will be mixed on the surface of silver and silver alloy ingots, and alumina powder will be dispersed in the entire silver and silver alloy ingot matrix. In the process of planing the ingot to remove the scale of silver and silver alloy ingots, because alumina fine sand and coarse sand are mixed on the surface of the ingot, in order to remove the alumina fine sand, more silver and silver alloy will be planed, reducing the silver. and silver alloy light ingot yield; after silver and silver alloy are rolled into finished strips or sheets, the alumina powder dispersed in the silver and silver alloy matrix is exposed, or forms white spot-like surface defects, or forms White line-shaped surface defects cause the surface quality of silver and silver alloy strips and sheets to be inconsistent, which greatly reduces the yield of products.

Contents of the invention

The technical problem to be solved by the present invention is to provide a crucible assembly for an induction furnace and a preparation method thereof for the above-mentioned deficiencies in the prior art. The crucible assembly of the present invention, which includes a crucible, a sintered layer, a filling layer, a crucible outer lining, and a sealing body, can realize the barrier melting high-temperature raw material from contacting the induction coil, avoid short circuit or furnace explosion, and can effectively prevent the inclusion of impurities in the product of the melting process from causing surface damage. Defects such as white spots and white lines can effectively improve the safety, yield and production efficiency of smelting silver or silver alloys.

In order to solve the above technical problems, the technical solution adopted in the present invention is: a crucible assembly for an induction furnace, the induction furnace is used for melting metal, the induction furnace includes a furnace body, the furnace body is provided with an induction coil, the The crucible assembly can be arranged in the induction coil, and it is characterized in that the crucible assembly includes a crucible assembly body and a sealing body arranged on the upper part of the crucible assembly body, and the crucible assembly body includes a cavity for accommodating raw materials , the opening at the top of the cavity;

The crucible assembly body includes a crucible, a sintered layer, a filling layer and a crucible lining, and the sintering layer, filling layer and crucible lining are sequentially arranged outside the crucible from the inside to the outside;

The raw material of described sintering layer comprises alumina coarse sand, alumina fine sand and water glass, and the mass ratio of described alumina coarse sand, alumina fine sand and water glass is (4.5～5.5):(2.5～3.5): (1.5～2.5); The raw material of described filling layer comprises alumina coarse sand and alumina fine sand, and the quality of described alumina coarse sand is 2 times～4 times of alumina fine sand quality; Described crucible outer lining comprises The outer lining filler layer and the fiber cloth layer, the outer lining filler layer is arranged in the fiber cloth layer, the raw materials of the outer lining filler layer include alumina coarse sand, alumina fine sand, alumina powder and water glass, the oxide The mass ratio of aluminum coarse sand, alumina fine sand, alumina powder and water glass is (1.5～2.5):(0.5～1.5):(0.5～1.5):(0.5～1.5); the raw materials of the sealing body include Metal oxide sand and water glass.

The above-mentioned crucible assembly for induction furnace is characterized in that the metal includes silver, silver alloy, gold, gold alloy, platinum, platinum alloy, palladium or palladium alloy.

The above-mentioned crucible assembly for an induction furnace is characterized in that the crucible is an alumina crucible, a zirconia crucible or a quartz crucible.

The above-mentioned crucible assembly for an induction furnace is characterized in that the particle size of the alumina coarse sand is 0.3 mm to 0.6 mm; the particle size of the alumina fine sand is 0.1 mm to 0.3 mm; the alumina powder is The particle size is 0.01mm-0.03mm; the material of the fiber cloth layer is asbestos cloth and/or glass silk cloth.

The above-mentioned crucible assembly for an induction furnace is characterized in that the crucible assembly also includes a glass cloth layer, the glass cloth layer is arranged between the sintered layer and the filling layer; the glass cloth layer is a glass cloth wound along the outer periphery of the sintered layer The formed glass silk cloth layer has 3-5 layers of winding layers.

The above-mentioned crucible assembly for an induction furnace is characterized in that the thickness of the sintered layer is 5 mm to 20 mm; the thickness of the outer lining filler layer is 30 mm to 50 mm.

In addition, the present invention also provides a method for preparing the above-mentioned crucible assembly for an induction furnace, which is characterized in that it comprises:

Step 1, providing a crucible provided with a sintered layer;

Step 2, providing the outer lining of the crucible;

Step 3, assembling the crucible with the sintered layer and the outer lining of the crucible, and setting the filling layer to obtain the crucible component body;

Step 4, sealing to obtain the crucible assembly.

The above-mentioned method is characterized in that a crucible provided with a sintered layer is provided in step 1, which specifically includes:

Step 101, mixing and stirring alumina coarse sand, alumina fine sand and water glass to obtain a raw material slurry for the sintering layer;

Step 102: Apply the sintered layer raw material slurry described in step 101 evenly on the crucible to a preset thickness, wrap it in kraft paper, dry in the shade for 12h-24h, remove the kraft paper, and obtain a crucible coated with the sintered layer raw material;

Step 103: Put the crucible coated with the sintered layer raw material described in step 102 into a box-type resistance furnace, bake at 200°C-400°C for 2h-4h, then sinter at 600°C-900°C for 3h-6h, Cooling gives a crucible provided with a sintered layer.

The above-mentioned method is characterized in that providing the outer lining of the crucible in step 2 specifically includes:

Step 201, mixing and stirring alumina coarse sand, alumina fine sand, alumina powder and water glass to obtain the raw material for the outer lining filler layer;

Step 202, placing the first fiber cloth in the induction coil in a cylindrical shape, so that the first fiber cloth is closely attached to the inner wall of the induction coil to obtain an induction coil with fiber cloth;

Step 203, placing the second fiber cloth on the refractory bricks, taking the raw material of the outer lining filler layer described in step 201 and laying it evenly on the second fiber cloth, compacting it so that the raw material of the outer lining filler layer is covered with the second fiber cloth, and obtaining Laying the second fiber cloth of the raw material of the packing layer of the outer lining; the second fiber cloth and the first fiber cloth are asbestos cloth or glass cloth; the thickness of the raw material of the packing layer of the outer lining after compaction is 30 mm to 50 mm;

Step 204, placing the induction coil with the fiber cloth laid out in step 202 vertically at the center of the second fiber cloth with the raw material for the outer lining filler layer, and placing the plastic tube in the induction coil with the fiber cloth , the plastic tube is positioned at the center of the induction coil provided with fiber cloth, an annular cavity is formed between the plastic tube and the induction coil provided with fiber cloth, and the raw material of the outer lining packing layer described in step 201 is filled to In the annular cavity, compacting and removing the plastic tube to obtain the crucible outer lining embryo body;

Step 205, standing the crucible outer lining embryo body described in step 204 until solidified to obtain the crucible outer lining embryo body after solidification;

Step 206, place the nickel rod vertically in the body of the cured crucible outer lining as described in step 205, place the cured crucible outer lining body with the nickel rod in the induction furnace, start the induction furnace, and bake for 4h to 6h , to get the outer lining of the crucible.

The above method is characterized in that in step 3, the crucible with the sintered layer and the outer lining of the crucible are assembled, the filling layer is set, and the crucible component body obtained specifically includes:

Step 301, placing the crucible with the sintered layer in step 1 at the center of the crucible outer lining in step 2, forming a chamber between the crucible with the sintered layer and the crucible outer lining, and installing Put the raw materials into the filling layer and compact them to obtain the crucible assembly body;

Sealing in step 4 to obtain the crucible assembly specifically includes:

Step 401, mixing metal oxide sand and water glass to obtain a viscous mixture for sealing body;

Step 402, laying the viscous mixture for the sealing body described in step 401 on the upper part of the crucible assembly body to form a sealing coating layer; the height of the sealing coating layer beyond the crucible assembly body is 10 mm to 20 mm;

Step 403, place the nickel rod vertically in the component body after forming the sealing coating layer in step 402, place the component body with the nickel rod placed in the induction furnace, start the induction furnace, bake for 4h-6h, and remove the nickel Rods were used to obtain crucible assemblies for induction furnaces.

Compared with the prior art, the present invention has the following advantages:

1. The crucible assembly for an induction furnace of the present invention includes a crucible assembly including a crucible, a sintered layer, a filling layer, an outer lining of the crucible, and a sealing body, which can prevent the high-temperature smelting raw material from contacting the induction coil, avoid short circuit or furnace explosion, and can effectively Avoiding defects such as white spots and white lines on the surface caused by impurities in the products during the smelting process can effectively improve the safety, yield and production efficiency of smelting silver or silver alloys.

2. The crucible assembly for an induction furnace of the present invention includes a crucible outer lining that is detachably arranged outside the filling layer, has a long service life and can be used permanently, and is convenient for easy separation of the crucible outer lining and the filling layer after knocking off the sealing body, thereby The replacement of the crucible with the sintered layer inside is beneficial to reduce the cost.

3. The crucible assembly for an induction furnace of the present invention includes a sintering layer arranged outside the crucible, and the raw materials of the sintering layer include coarse alumina sand, fine alumina sand and water glass, which can effectively prevent the crucible from cracking, avoiding porcelain loss, and achieving Effective protection for the crucible.

4. Preferably, the crucible assembly for an induction furnace of the present invention further includes a glass cloth layer arranged between the sintered layer and the filling layer, which can further block the sand body in the filling layer from entering the high-temperature smelting raw material liquid.

5. The crucible assembly for an induction furnace of the present invention includes a sintered layer raw material composed of alumina coarse sand, alumina fine sand and water glass, and a filling layer raw material composed of alumina coarse sand and alumina fine sand, which is effective in forming On the basis of sintering protection and filling protection, the aluminum oxide powder in the prior art is further prevented from entering the smelting high-temperature raw material liquid during the smelting process.

The technical solutions of the present invention will be described in further detail below in conjunction with the accompanying drawings and embodiments.

Instructions attached

FIG. 1 is a schematic structural view of a crucible assembly for an induction furnace in Example 1.

Figure 2 is the 50 μm scale SEM photo of the silver alloy ribbon obtained before the test.

Figure 3 is a 10 μm scale SEM photo of the silver alloy strip obtained before the test.

Figure 4 is the EDS photo of the silver alloy strips obtained before the test.

FIG. 5 is an energy spectrum analysis diagram corresponding to FIG. 4 .

Fig. 6 is a SEM photo of the silver alloy ribbon obtained after the test.

Detailed ways

Example 1

This embodiment provides a crucible assembly for an induction furnace. As shown in FIG. 1, the induction furnace is used for melting metals, and the metals include silver, silver alloys, gold, gold alloys, platinum, platinum alloys, palladium or palladium alloys , the induction furnace includes a furnace body, an induction coil is arranged in the furnace body, and the crucible assembly can be arranged in the induction coil, and the crucible assembly includes a crucible assembly body and an upper part of the crucible assembly body Sealing body 6, the crucible assembly body includes a cavity that can accommodate raw materials, and the top of the cavity is open; the crucible assembly body includes a wall body that surrounds the cavity, and the sealing body 6 is arranged on the on the wall body;

The crucible assembly body includes a crucible 1, a sintered layer 2, a filling layer 4 and a crucible outer lining 5, and the cavity is formed in the crucible 1, and the sintering layer 2, the filling layer 4 and the crucible outer lining 5 are from the inside to the The outside is sequentially arranged outside the crucible 1;

The crucible 1 is an alumina crucible, a zirconia crucible or a quartz crucible;

The raw materials of the sintered layer 2 include coarse alumina sand, fine alumina sand and water glass, and the mass ratio of the coarse alumina sand, fine alumina sand and water glass is (4.5～5.5):(2.5～3.5) : (1.5～2.5), such as can be 4.5:2.5:1.5, 5.5:3.5:2.5 or 5:3:2, the mass ratio of alumina coarse sand, alumina fine sand and water glass described in the present embodiment is 5:3:2; the particle size of the alumina coarse sand is 0.3mm-0.6mm, and the particle size of the alumina fine sand is 0.1mm-0.3mm;

The raw material of the filling layer 4 includes alumina coarse sand and alumina fine sand, and the quality of the alumina fine sand is 2 to 4 times that of the alumina fine sand, for example, it can be 2 times, 3 times or 4 times, The quality of alumina coarse sand described in the present embodiment is 3 times of alumina fine sand quality;

The crucible outer lining 5 includes an outer lining filler layer and a fiber cloth layer, the outer lining filler layer is arranged in the fiber cloth layer, and the raw materials of the outer lining filler layer include alumina coarse sand, alumina fine sand, alumina powder And water glass, the mass ratio of described aluminum oxide coarse sand, aluminum oxide fine sand, aluminum oxide powder and water glass is (1.5～2.5): (0.5～1.5):(0.5～1.5):(0.5～1.5), Such as can be 1.5: 1.5: 0.5: 0.5, 2.5: 0.5: 1.5: 1.5 or 2: 1: 1: 1, the alumina coarse sand, alumina fine sand, alumina powder and water glass described in this embodiment The mass ratio is 2:1:1:1; the particle size of the alumina powder is 0.01 mm to 0.03 mm; the fiber cloth layer is made of asbestos cloth and/or glass silk cloth;

The raw materials of the sealing body 6 include metal oxide sand and water glass, the quality of the metal oxide sand is 3 to 4 times that of the water glass, and the metal oxide sand is magnesia sand or alumina sand; The particle diameters of the magnesia sand and the alumina sand are both 0.01 to 0.3 mm;

The crucible 1 includes a cylinder and a bottom arranged at the lower part of the cylinder, the cylinder and the bottom enclose to form the cavity; the shape of the crucible cylinder is preferably a straight cylinder;

The crucible assembly for the induction furnace of this embodiment also includes a glass cloth layer 3, the glass cloth layer 3 is arranged between the sintered layer 2 and the filling layer 4; The glass silk cloth layer 3 formed by winding the outer circumference is 3 to 5 layers; the temperature resistance of the glass silk cloth can reach 550-1200°C, and the glass silk cloth is purchased from Caiti or Lanlia;

In the crucible assembly for an induction furnace in this embodiment, the thickness of the sintered layer 2 is 5 mm to 20 mm; the thickness of the outer lining filler layer is 30 mm to 50 mm;

The filling layer 4 is composed of a vertical wall filling part and a bottom filling part, the vertical wall filling part corresponds to the cylinder part of the crucible 1, the thickness of the vertical wall filling part is 2 to 3 times the wall thickness of the crucible 1, and the bottom filling part The thickness is 1.5 to 2.5 times the wall thickness of the crucible 1 .

Example 2

This embodiment provides a method for preparing the crucible assembly for the induction furnace described in Embodiment 1, comprising:

Step 1, providing a crucible provided with a sintered layer, specifically including:

Step 101, mix the alumina coarse sand, alumina fine sand and water glass according to the mass ratio of 5:3:2, and stir to obtain the sintered layer raw material slurry; the stirring is to stir until the system is hung on the alumina stirring rod does not fall;

Step 102: Apply the sintering layer raw material slurry described in step 101 evenly on the crucible 1 to a predetermined thickness, wrap the outer surface of the sintering layer raw material slurry applied on the crucible 1 with kraft paper for fixing, dry in the shade for 15 hours, and remove the kraft paper , to obtain a crucible coated with a sintered layer raw material; the preset thickness is 10mm;

Step 103: Put the crucible coated with the sintered layer raw material described in step 102 into a box-type resistance furnace, bake at 300°C for 3 hours, then sinter at 800°C for 4 hours, and cool with the furnace to obtain Crucible for sintered layer;

Step 2, providing the crucible outer lining 5, specifically including:

Step 201, mix alumina coarse sand, alumina fine sand, alumina powder and water glass according to the mass ratio of 2:1:1:1, and stir to obtain the raw material of the outer lining packing layer; the stirring is to stir until the system hangs on Does not fall off on the alumina stirring rod;

Step 202, placing the first fiber cloth in the induction coil in a cylindrical shape, so that the first fiber cloth is closely attached to the inner wall of the induction coil to obtain an induction coil equipped with fiber cloth; the shape of the first fiber cloth is a rectangle, The length of the first fiber cloth is 1.5 times the inner perimeter of the induction coil, and the width of the first fiber cloth is the height of the induction coil+100mm;

Step 203, place the second fiber cloth on the refractory brick, take part of the raw material of the outer lining packing layer described in step 201, evenly lay it on the second fiber cloth, and compact it, so that the raw material of the outer lining packing layer is covered with the second fiber cloth, Obtain the second fiber cloth that is laid with the raw material of the outer lining packing layer; The diameter of the second fiber cloth is 1.2 times of the induction coil diameter; The second fiber cloth and the first fiber cloth are both asbestos cloth; The raw material thickness of the outer lining packing layer is 40mm;

Step 204, placing the induction coil with the fiber cloth laid out in step 202 vertically at the center of the second fiber cloth with the raw material for the outer lining filler layer, and placing the plastic tube in the induction coil with the fiber cloth , so that the plastic tube is located at the center of the induction coil equipped with fiber cloth, an annular cavity is formed between the plastic tube and the induction coil provided with fiber cloth, and part of the raw material of the outer lining filler layer described in step 201 is filled Into the annular cavity, compacting, removing the plastic tube to obtain the crucible outer lining body; the diameter of the plastic tube—the diameter of the crucible ≥ 60mm;

Step 205, standing the crucible outer lining body described in step 204 for 36 hours until solidified to obtain the solidified crucible outer lining body;

Step 206, place the nickel rod vertically in the center of the solidified crucible outer lining body described in step 205, place the cured crucible outer lining body with the nickel rod placed in the induction furnace, start the induction furnace, and bake 5h, the outer lining 5 of the crucible was obtained; to remove moisture; the furnace temperature was 1000°C;

Step 3, assembling the crucible with the sintered layer and the crucible outer lining 5, setting the filling layer, and obtaining the crucible assembly body; specifically including:

Step 301, placing the crucible provided with the sintered layer in step 103 at the center of the crucible outer lining described in step 206, a chamber is formed between the crucible provided with the sintered layer and the outer lining of the crucible, and the Put the filling layer raw material and compact it to obtain the crucible assembly body; the filling layer raw material is a mixture of alumina coarse sand and alumina fine sand, and the quality of the alumina coarse sand is 3 times the quality of the alumina fine sand; The top of the sintered layer and the top of the crucible lining are flush with the opening of the crucible, and the distance between the filling layer 4 and the opening of the crucible is 25 mm;

Step 4, sealing to obtain the crucible assembly, specifically including:

Step 401, mixing metal oxide sand and water glass at a mass ratio of 3:1 to obtain a viscous mixture for a sealing body;

Step 402, laying the viscous mixture for the sealing body described in step 401 on the upper part of the crucible assembly body described in step 301 to form a sealing coating layer; the height of the sealing coating layer beyond the crucible assembly body part is 15 mm, and the sealing The coating layer fills the space between the filling layer 4 and the opening of the crucible; the crucible assembly for the induction furnace in this embodiment can be smelted 45 to 50 times, and when it needs to be replaced, the outer lining of the crucible and the filling layer can be realized by taking out the sealing body. separation of

Step 403, place the nickel rod vertically in the center of the component body after the sealing coating layer is formed in step 402, place the component body with the nickel rod in the induction furnace, start the induction furnace, bake for 5 hours, remove Nickel rods are removed to obtain a crucible assembly for an induction furnace; to remove moisture; the furnace temperature is 1000°C.

Example 3

This embodiment is the same as Embodiment 2, except that step 3 further includes winding the glass cloth onto the crucible provided with the sintered layer, and the number of winding layers is 3 to 5 layers; The final glass cloth is not loose.

Example 4

This embodiment provides a method for preparing the crucible assembly for the induction furnace described in Embodiment 1, comprising:

Step 1, providing a crucible provided with a sintered layer, specifically including:

Step 101, mix the alumina coarse sand, alumina fine sand and water glass according to the mass ratio of 5:3:2, and stir to obtain the sintered layer raw material slurry; the stirring is to stir until the system is hung on the alumina stirring rod does not fall;

Step 102: Apply the sintering layer raw material slurry described in step 101 evenly on the crucible 1 to a preset thickness, wrap the sintering layer raw material slurry applied on the crucible 1 with kraft paper for fixing, dry in the shade for 12 hours, and remove the kraft paper , to obtain a crucible coated with a sintered layer raw material; the preset thickness is 5mm;

Step 103: Put the crucible coated with the sintered layer raw material described in step 102 into a box-type resistance furnace, bake at 200°C for 4 hours, then sinter at 600°C for 6 hours, and cool with the furnace to obtain a Crucible for sintered layer;

Step 2, providing the crucible outer lining 5, specifically including:

Step 201, mix alumina coarse sand, alumina fine sand, alumina powder and water glass according to the mass ratio of 2:1:1:1, and stir to obtain the raw material of the outer lining packing layer; the stirring is to stir until the system hangs on Does not fall off on the aluminum oxide stirring rod;

Step 202, placing the first fiber cloth in the induction coil in a cylindrical shape, so that the first fiber cloth is closely attached to the inner wall of the induction coil to obtain an induction coil equipped with fiber cloth; the shape of the first fiber cloth is a rectangle, The length of the first fiber cloth is 1.5 times the inner perimeter of the induction coil, and the width of the first fiber cloth is the height of the induction coil+100mm;

Step 203, place the second fiber cloth on the refractory brick, take part of the raw material of the outer lining packing layer described in step 201, evenly lay it on the second fiber cloth, and compact it, so that the raw material of the outer lining packing layer is covered with the second fiber cloth, Obtain the second fiber cloth that is laid with the raw material of the outer lining filler layer; the diameter of the second fiber cloth is 1.2 times the diameter of the induction coil; the second fiber cloth is asbestos cloth, and the second fiber cloth is glass silk cloth; The thickness of the raw material of the outer lining packing layer after compaction is 30mm;

Step 204, placing the induction coil with the fiber cloth laid out in step 202 vertically at the center of the second fiber cloth with the raw material for the outer lining filler layer, and placing the plastic tube in the induction coil with the fiber cloth , so that the plastic tube is located at the center of the induction coil equipped with fiber cloth, an annular cavity is formed between the plastic tube and the induction coil provided with fiber cloth, and part of the raw material of the outer lining filler layer described in step 201 is filled Into the annular cavity, compacting, removing the plastic tube to obtain the crucible outer lining body; the diameter of the plastic tube—the diameter of the crucible ≥ 60mm;

Step 205, standing still the crucible outer lining embryo body described in step 204 for 24 hours until solidified to obtain the solidified crucible outer lining embryo body;

Step 206, place the nickel rod vertically in the center of the solidified crucible outer lining body described in step 205, place the cured crucible outer lining body with the nickel rod placed in the induction furnace, start the induction furnace, and bake 4h, the outer lining 5 of the crucible was obtained; to remove moisture; the furnace temperature was 800°C;

Step 3, assembling the crucible with the sintered layer and the crucible outer lining 5, setting the filling layer, and obtaining the crucible assembly body; specifically including:

Step 301, placing the crucible provided with the sintered layer in step 103 at the center of the crucible outer lining described in step 206, a chamber is formed between the crucible provided with the sintered layer and the outer lining of the crucible, and the Put the filling layer raw material and compact it to obtain the crucible assembly body; the filling layer raw material is a mixture of alumina coarse sand and alumina fine sand, and the quality of the alumina coarse sand is 3 times the quality of the alumina fine sand; The top of the sintered layer and the top of the crucible lining are flush with the opening of the crucible, and the distance between the filling layer 4 and the opening of the crucible is 20mm;

Step 4, sealing to obtain the crucible assembly, specifically including:

Step 401, mixing metal oxide sand and water glass at a mass ratio of 3:1 to obtain a viscous mixture for a sealing body;

Step 402, laying the viscous mixture for the sealing body described in step 401 on the upper part of the crucible assembly body described in step 301 to form a sealing coating layer; the height of the sealing coating layer beyond the crucible assembly body part is 10 mm, and the sealing The coating layer fills the space between the filling layer 4 and the opening of the crucible;

Step 403, place the nickel rod vertically in the center of the component body after forming the sealing coating layer in step 402, place the component body with the nickel rod in the induction furnace, start the induction furnace, bake for 4 hours, remove Nickel rods are removed to obtain a crucible assembly for an induction furnace; to remove moisture; the furnace temperature is 800°C.

The performance of the crucible assembly for induction furnace obtained in this embodiment is basically the same as that in Embodiment 2.

Example 5

This embodiment provides a method for preparing the crucible assembly for the induction furnace described in Embodiment 1, comprising:

Step 1, providing a crucible provided with a sintered layer, specifically including:

Step 101, mix the alumina coarse sand, alumina fine sand and water glass according to the mass ratio of 5:3:2, and stir to obtain the sintered layer raw material slurry; the stirring is to stir until the system is hung on the alumina stirring rod does not fall;

Step 102: Spread the sintering layer raw material slurry described in step 101 evenly on the crucible 1 to a preset thickness, wrap the sintering layer raw material slurry applied on the crucible 1 with kraft paper for fixing, dry in the shade for 24 hours, and remove the kraft paper , to obtain a crucible coated with a sintered layer raw material; the preset thickness is 20mm;

Step 103: Put the crucible coated with the sintered layer raw material described in step 102 into a box-type resistance furnace, bake at 400°C for 2 hours, then sinter at 900°C for 3 hours, and cool with the furnace to obtain a Crucible for sintered layer;

Step 2, providing the crucible outer lining 5, specifically including:

Step 201, mix alumina coarse sand, alumina fine sand, alumina powder and water glass according to the mass ratio of 2:1:1:1, and stir to obtain the raw material of the outer lining packing layer; the stirring is to stir until the system hangs on Does not fall off on the aluminum oxide stirring rod;

Step 202, placing the first fiber cloth in the induction coil in a cylindrical shape, so that the first fiber cloth is closely attached to the inner wall of the induction coil to obtain an induction coil equipped with fiber cloth; the shape of the first fiber cloth is a rectangle, The length of the first fiber cloth is 1.5 times the inner perimeter of the induction coil, and the width of the first fiber cloth is the height of the induction coil+100mm;

Step 203, place the second fiber cloth on the refractory brick, take part of the raw material of the outer lining packing layer described in step 201, evenly lay it on the second fiber cloth, and compact it, so that the raw material of the outer lining packing layer is covered with the second fiber cloth, Obtain the second fiber cloth that is laid with the raw material of the outer lining packing layer; The diameter of the second fiber cloth is 1.2 times of the induction coil diameter; The second fiber cloth and the first fiber cloth are glass silk cloth; The raw material thickness of the outer lining packing layer is 50mm;

Step 204, placing the induction coil with the fiber cloth laid out in step 202 vertically at the center of the second fiber cloth with the raw material for the outer lining filler layer, and placing the plastic tube in the induction coil with the fiber cloth , so that the plastic tube is located at the center of the induction coil equipped with fiber cloth, an annular cavity is formed between the plastic tube and the induction coil provided with fiber cloth, and part of the raw material of the outer lining filler layer described in step 201 is filled Into the annular cavity, compacting, removing the plastic tube to obtain the crucible outer lining body; the diameter of the plastic tube—the diameter of the crucible ≥ 60mm;

Step 205, standing the crucible outer lining body described in step 204 for 48 hours until solidified to obtain the solidified crucible outer lining body;

Step 206, place the nickel rod vertically in the center of the solidified crucible outer lining body described in step 205, place the cured crucible outer lining body with the nickel rod placed in the induction furnace, start the induction furnace, and bake 6h, the outer lining 5 of the crucible was obtained; to remove moisture; the furnace temperature was 1200°C;

Step 3, assembling the crucible with the sintered layer and the crucible outer lining 5, setting the filling layer, and obtaining the crucible assembly body; specifically including:

Step 301, placing the crucible provided with the sintered layer in step 103 at the center of the crucible outer lining described in step 206, a chamber is formed between the crucible provided with the sintered layer and the outer lining of the crucible, and the Put the filling layer raw material and compact it to obtain the crucible assembly body; the filling layer raw material is a mixture of alumina coarse sand and alumina fine sand, and the quality of the alumina coarse sand is 3 times the quality of the alumina fine sand; The top of the sintered layer and the top of the crucible lining are flush with the opening of the crucible, and the distance between the filling layer 4 and the opening of the crucible is 30mm;

Step 4, sealing to obtain the crucible assembly, specifically including:

Step 401, mixing metal oxide sand and water glass at a mass ratio of 4:1 to obtain a viscous mixture for sealing body;

Step 402, laying the viscous mixture for the sealing body described in step 401 on the upper part of the crucible assembly body described in step 301 to form a sealing coating layer; the height of the sealing coating layer beyond the crucible assembly body part is 20mm, and the sealing The coating layer fills the space between the filling layer 4 and the opening of the crucible;

Step 403, place the nickel rod vertically in the center of the component body after forming the sealing coating layer in step 402, place the component body with the nickel rod in the induction furnace, start the induction furnace, bake for 6 hours, remove Nickel rods are removed to obtain a crucible assembly for an induction furnace; to remove moisture; the furnace temperature is 1200°C.

The performance of the crucible assembly for induction furnace obtained in this embodiment is basically the same as that in Embodiment 2.

Performance evaluation:

Table 1 shows the yield of silver alloy smelting with the crucible assembly used in the induction furnace in Example 2. Wherein the smelting process includes: putting the silver alloy material into the crucible, sealing the furnace to evacuate, when the vacuum degree is less than 0.1Pa, start heating, the heating power is 10kw, until the silver in the crucible is completely melted, continue heating for 6-8min refining, close the valve for heating , fill with argon gas to 0.06MPa～0.08MPa, increase the heating power to 25kw, and the heating time is 2min, which can be 1100℃, reduce the power to 10kw, pour with electricity, cool with the furnace for 15min, and come out of the furnace.

In Table 1, the yield rate before the test is the product yield rate of the above-mentioned smelting process with the traditional alumina crucible, and the yield rate after the test is the product yield rate of the above-mentioned smelting process with the crucible assembly prepared by the method described in Example 2, wherein the traditional The alumina crucible is made of 99% Al ₂ O ₃ alumina crucible, that is, the crucible 1 in step 102 of embodiment 2. It can be seen from Table 1 that the yield rate of the crucible assembly of the present invention is significantly improved, indicating that the crucible assembly of the present invention can effectively avoid the pollution of the aluminum oxide powder in the traditional crucible to the silver alloy material.

The yield rate of silver alloy smelting carried out by induction furnace crucible assembly in the embodiment 2 of table 1

Figure 2 and Figure 3 are SEM photos of the silver alloy strips obtained before the test, wherein Figure 2 is the picture under the 50 μm scale, and Figure 3 is the picture under the 10 μm scale, it can be seen that there are white lines, white dot lines and lines on the surface of the silver alloy strip. Defects such as the inclusion of particles in the middle.

Figure 4 is the EDS photo of the silver alloy ribbon obtained before the test, and Figure 5 is the energy spectrum analysis diagram corresponding to Figure 4. Combining Figure 4 and Figure 5, it can be known that the inclusions in the silver alloy ribbon are alumina particles. Combining Figures 2 to 5, it can be seen that the occurrence of white spots and white lines on the surface of the silver alloy strip is one of the main reasons for the low yield. It may be that the hard alumina particles are not easily deformed during the silver alloy rolling process. Destroy the surface of the silver alloy, causing the surface quality of the silver alloy to be substandard and the yield rate to be reduced.

Fig. 6 is the SEM photograph of the silver alloy band that obtains after the test, as can be seen from Fig. 6, after the test, the silver alloy surface has no white spot, white line, and the surface quality is good, has higher yield, shows that the crucible assembly of the present invention can effectively Avoid the pollution of alumina powder to metal materials.

The above are only preferred embodiments of the present invention, and do not limit the present invention in any way. All simple modifications, changes and equivalent structural changes made to the above embodiments according to the technical essence of the invention still belong to the technical solution of the present invention. within the scope of protection.

Claims (10)

1. The crucible assembly for the induction furnace is used for smelting metal, and comprises a furnace body, wherein an induction coil is arranged in the furnace body, and the crucible assembly can be arranged in the induction coil;

the crucible assembly body comprises a crucible (1), a sintering layer (2), a filling layer (4) and a crucible outer lining (5), wherein the sintering layer (2), the filling layer (4) and the crucible outer lining (5) are sequentially arranged outside the crucible (1) from inside to outside;

the raw materials of the sintering layer (2) comprise coarse alumina sand, fine alumina sand and water glass, wherein the mass ratio of the coarse alumina sand to the fine alumina sand to the water glass is (4.5-5.5) to (2.5-3.5) to (1.5-2.5); the raw materials of the filling layer (4) comprise alumina coarse sand and alumina fine sand, and the mass of the alumina coarse sand is 2-4 times that of the alumina fine sand; the crucible outer lining (5) comprises an outer lining packing layer and a fiber cloth layer, the outer lining packing layer is arranged in the fiber cloth layer, the outer lining packing layer comprises raw materials of alumina coarse sand, alumina fine sand, alumina powder and water glass, and the mass ratio of the alumina coarse sand to the alumina fine sand to the alumina powder to the water glass is (1.5-2.5): (0.5-1.5): 0.5-1.5); the sealing body (6) comprises metal oxide sand and water glass as raw materials.

2. The crucible assembly for an induction furnace of claim 1, wherein the metal comprises silver, silver alloy, gold alloy, platinum alloy, palladium or palladium alloy.

3. Crucible assembly for induction furnaces according to claim 1, characterized in that the crucible (1) is an alumina crucible, a zirconia crucible or a quartz crucible.

4. The crucible assembly for an induction furnace according to claim 1, wherein the alumina grit has a particle size of 0.3mm to 0.6mm; the grain sizes of the alumina fine sands are all 0.1 mm-0.3 mm; the grain diameter of the alumina powder is 0.01 mm-0.03 mm; the material of fibre cloth layer is asbestos cloth and/or glass silk cloth.

5. The crucible assembly for an induction furnace according to claim 1, further comprising a glass fiber cloth layer (3), the glass fiber cloth layer (3) being disposed between the sintered layer (2) and the filling layer (4); the glass fiber cloth layer (3) is formed by winding glass fiber cloth along the periphery of the sintering layer (2), and the number of winding layers is 3-5.

6. Crucible assembly for induction furnaces according to claim 1, characterized in that the sintered layer (2) has a thickness of 5mm to 20mm; the thickness of the outer lining filler layer is 30 mm-50 mm.

7. A method for preparing the crucible assembly for an induction furnace according to any one of claims 1 to 6, comprising:

step one, providing a crucible provided with a sintering layer;

step two, providing a crucible outer lining (5);

thirdly, assembling the crucible provided with the sintering layer and a crucible outer lining (5), and arranging a filling layer (4) to obtain a crucible assembly body;

and step four, sealing to obtain the crucible assembly.

8. Method according to claim 7, characterized in that the provision of a crucible provided with a sintered layer in step one comprises in particular:

step 101, mixing and stirring alumina coarse sand, alumina fine sand and water glass to obtain sintering layer raw material slurry;

step 102, uniformly coating the sintering layer raw material slurry obtained in the step 101 on a crucible (1) to a preset thickness, wrapping kraft paper, drying in the shade for 12-24 hours, and removing the kraft paper to obtain the crucible coated with the sintering layer raw material;

103, putting the crucible coated with the sintering layer raw material in the step 102 into a box-type resistance furnace, baking for 2-4 h at 200-400 ℃, then sintering for 3-6 h at 600-900 ℃, and cooling along with the furnace to obtain the crucible provided with the sintering layer.

9. The method according to claim 7, wherein the step two of providing the outer crucible lining (5) comprises:

step 201, mixing and stirring alumina coarse sand, alumina fine sand, alumina powder and water glass to obtain a raw material of an outer lining filler layer;

202, placing a first fiber cloth into an induction coil in a cylindrical shape, so that the first fiber cloth is tightly attached to the inner wall of the induction coil, and obtaining the induction coil with the fiber cloth;

step 203, placing a second fiber cloth on the refractory bricks, uniformly paving the raw material of the outer lining packing layer on the second fiber cloth in the step 201, and compacting to fully pave the raw material of the outer lining packing layer on the second fiber cloth to obtain the second fiber cloth paved with the raw material of the outer lining packing layer; the second fiber cloth and the first fiber cloth are asbestos cloth or glass fiber cloth; the thickness of the raw material of the compacted outer lining filler layer is 30 mm-50 mm;

step 204, vertically placing the induction coil provided with the fiber cloth in the step 202 at the center of the second fiber cloth paved with the raw material of the outer lining filler layer, placing a plastic pipe in the induction coil provided with the fiber cloth to enable the plastic pipe to be positioned at the center of the induction coil provided with the fiber cloth, forming an annular cavity between the plastic pipe and the induction coil provided with the fiber cloth, filling the raw material of the outer lining filler layer in the step 201 into the annular cavity, compacting, and removing the plastic pipe to obtain a blank body of the outer lining of the crucible;

step 205, standing the crucible outer lining blank body obtained in the step 204 until the crucible outer lining blank body is solidified to obtain a solidified crucible outer lining blank body;

and step 206, vertically placing the nickel rod in the solidified crucible outer lining blank body obtained in the step 205, placing the solidified crucible outer lining blank body in which the nickel rod is placed in an induction furnace, starting the induction furnace, and baking for 4-6 hours to obtain the crucible outer lining (5).

10. The method according to claim 7, characterized in that assembling in step three the crucible provided with the sintered layer and the outer crucible lining (5), providing the filling layer, obtaining the body of the crucible assembly in particular comprises:

step 301, placing the crucible provided with the sintering layer in the step one at the center of the outer lining of the crucible in the step two, forming a cavity between the crucible provided with the sintering layer and the outer lining of the crucible, filling a filling layer raw material into the cavity, and compacting to obtain a crucible assembly body;

sealing in the fourth step to obtain the crucible assembly, which specifically comprises the following steps:

step 401, mixing metal oxide sand and water glass to obtain a viscous mixture for a sealing body;

402, paving the viscous mixture for the sealing body in the step 401 on the upper part of the crucible assembly body to form a sealing coating layer; the height of the sealing coating layer exceeding the crucible assembly body is 10-20 mm;

and 403, vertically placing the nickel rod in the assembly body with the seal coating layer formed in the step 402, placing the assembly body with the nickel rod in an induction furnace, starting the induction furnace, baking for 4-6 hours, and removing the nickel rod to obtain the crucible assembly for the induction furnace.

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