A method for preparing a casting mold shell for a zirconium-niobium alloy artificial joint prosthesis

Abstract

The application relates to a preparation method of a lost foam casting mold shell suitable for a zirconium-niobium alloy artificial joint prosthesis, belonging to the field of preparation of lost foam casting mold shells. A joint wax mold is assembled to form a mold group, then the wax mold is cleaned with a cleaning liquid, the area with excessive cleaning liquid is blown with a high-pressure air gun before a surface layer slurry, then the surface layer slurry, the temporary surface layer slurry, the back layer slurry and the sealing slurry are sequentially immersed and coated, sand is hung after each time, drying and hardening are carried out, and a novel zirconium-niobium alloy joint shell is obtained after high-temperature baking after dewaxing. The application breaks the limitation that the zirconium-niobium alloy joint is usually only subjected to a forging process, a mold shell capable of bearing the high melting point of the zirconium-niobium alloy is obtained through research on the proportion and dosage of the binder, the surface layer of the mold shell does not react with the surface of the zirconium-niobium alloy, the surface requirement of the medical implant is high, a good foundation is laid for the melting and pouring of the artificial joint prosthesis mold shell, and the application is helpful for the high-end development of the artificial joint.

Description

Technical Field

[0001] This invention belongs to the field of investment casting mold shell technology, specifically relating to a method for preparing an investment casting mold shell for a zirconium-niobium alloy artificial joint prosthesis. Background Technology

[0002] Zirconium-niobium alloy is an ideal new material for manufacturing high-end artificial joint prostheses. Joint prostheses made from this material can effectively relieve pain and improve knee joint mobility, reduce prosthesis loosening and surrounding bone resorption. Clinical and imaging evaluations have confirmed its good efficacy, and it is increasingly being used in clinical practice. Currently, only the orthopedic giant Smith & Nephew uses forging and machining processes to produce these joints. Compared to the traditional investment casting process for cobalt-chromium-molybdenum alloy joints, the forging and machining process for zirconium-niobium joints is inherently complex, difficult to mass-produce, and costly, resulting in high import prices.

[0003] This invention aims to provide a process scheme for investment casting of zirconium-niobium alloy joints, in which the preparation of the ceramic shell is a key step in investment casting. Investment casting requires the shell to have sufficient strength at both room temperature and high temperature, thermochemical stability, low coefficient of thermal expansion, high permeability, low residual strength, and a certain surface strength; it is usually composed of a highly inert, dense surface layer and a high-temperature resistant, permeable back layer. To suppress the physicochemical reaction between the molten metal and the shell, the surface refractory material and binder used to prepare the surface shell must have low roughness and high-temperature chemical inertness to the molten metal. Due to the high chemical reactivity of zirconium-niobium alloys in the molten state and the pouring temperature exceeding 2000℃, the surface of the shell prepared by conventional zircon powder (sand) surface ceramic refractory material is not dense enough and easily reacts with the metal to form a reaction layer, which cannot meet the requirements for precision forming of zirconium-niobium alloys. Therefore, the preparation of the shell for investment casting of zirconium-niobium alloy artificial joint prostheses is a difficult point in the investment casting process. However, no shell preparation process suitable for investment casting of zirconium-niobium alloy joints has been reported to date. Therefore, this invention, based on the characteristics of zirconium-niobium alloys and casting process conditions, designs the formulation of shell surface layer and back layer materials, optimizes the process parameters of shell slurry application, sanding, dewaxing and calcination, and develops a new ceramic surface layer system that can withstand ultra-high temperatures of 2000℃ and has high inertness. This inhibits the reaction between the shell surface layer and the molten metal, forming an interface reaction inhibition technology between the zirconium-niobium high-temperature alloy melt and the surface layer, thereby improving the surface quality of the casting. Summary of the Invention

[0004] The purpose of this invention is to provide a novel method for preparing the investment casting mold shell of a zirconium-niobium alloy artificial joint prosthesis.

[0005] The mold shell formula selected in this invention is as follows: the mold shell consists of a surface layer, a yttrium oxide sand layer, a multi-layered back layer, and bauxite sand. The surface layer slurry formula is: 66-75 wt% yttrium oxide powder, 3.5-7 wt% zirconium acetate, 14.7-24 wt% ammonium metatungstate, 1.7-5.2 wt% deionized water, and 0.5-2 wt% high-purity boric acid. The yttrium oxide powder is 300-400 mesh powder particles. The back layer slurry formula is composed of a binder made of ethyl silicate, alcohol, and hydrochloric acid, and bauxite powder. The bauxite powder is 200-300 mesh powder particles. Bauxite sand is then sprinkled on top of the back layer slurry.

[0006] The present invention discloses a method for preparing a zirconium-niobium alloy artificial joint prosthesis by investment casting, comprising the following steps.

[0007] Step (1) Wax mold cleaning: Clean the assembled wax mold assembly with methyl ethyl ketone and then with a penetrant. Before pouring the surface slurry, use a high-pressure air gun to blow air into areas with excessive solution to avoid liquid accumulation in these areas. After cleaning, let the mold assembly stand and dry for 24 hours.

[0008] Step (2) Surface Layer: The surface layer adhesive is prepared in the following mass ratio: deionized water: zirconium acetate: ammonium metatungstate (0.5-1.5: 1.0-2.0: 4.0-5.0). After preparing these three solutions, add 0.5-2 wt.% of high-purity boric acid. Mix the adhesive according to the ratio, stirring every 3 hours to ensure the powder is completely dissolved in the solution. The adhesive should be transparent with no powder suspended on the liquid surface. Let it stand for 24 hours in a closed and dry environment. Then, mix the 24-hour-standing adhesive with 30... Yttrium oxide powder of 0-400 mesh is mixed, and the solid-liquid ratio of the slurry is 2.0-3.0:1. 2ml / 30kg of rapid penetrant and 2ml / 30kg of defoamer n-octanol are added. The mixture is then stirred by rotation and vacuumed. The resulting surface slurry has a viscosity of 18-28 seconds and an effective lifespan of 30-60 minutes. After the slurry is coated with a wax mold, 60-80 mesh yttrium oxide sand is sprinkled on the surface. The mixture is then dried for 24 hours under constant temperature and humidity (temperature 23±3℃, humidity 70±5%) to obtain the surface shell.

[0009] Step (3) Facing layer: The bonding agent ratio of the facing layer is deionized water: zirconium acetate: ammonium metatungstate (0.8-2.0: 1.0-2.0: 4.0-5.0 by mass). After mixing the bonding agent ratio, stir it once every 3 hours to make the powder completely dissolve in the solution. The bonding agent is transparent and no powder is suspended on the liquid surface. Let it stand for 24 hours in a closed and dry environment. Mix the binder with 300-400 mesh yttrium oxide powder, with a slurry solid-liquid ratio of 0.8-2.0:1. Add 2 ml / 30 kg of defoamer n-octanol and mix by high-speed and low-speed rotary stirring. The viscosity of the obtained slurry for the facing layer is 8-10 seconds. The viscosity of the slurry increases after 60 minutes. Add binder to reduce the viscosity. The effective shelf life under cold storage is 12 hours. After the slurry is coated onto the module, sprinkle 40-70 mesh yttrium oxide sand on the facing layer. Then, dry it for 24 hours under constant temperature and humidity (temperature 23±3℃, humidity 60±5%) to obtain the facing layer shell.

[0010] Step (4) Backing Layer: The adhesive ratio for Backing Layer 1 and Backing Layer 2 is alcohol:ethyl silicate:hydrochloric acid (5.0-6.0L:5.0-6.0L:100ml). After mixing the adhesives, let them stand for 48 hours in a closed and dry environment. The solid-liquid ratio of Backing Layer 1 and Backing Layer 2 slurry is 0.5-1.5:0.5-1.5. Backing Layer 1 and Backing Layer 2 slurry is made by mixing the ethyl silicate adhesive that has stood for 48 hours with 200-300 mesh bauxite powder, stirring in a mixer for 1 hour at a stirring speed of 100r / min, and the viscosity of Backing Layer 1 and Backing Layer 2 slurry is 3-5 seconds. For back layer 3 and subsequent back layers, silica sol is used as the binder, with a solid-liquid ratio of 1.5-2.5:1. The prepared silica sol is mixed with bauxite powder (200-300 mesh) and stirred for 1 hour at a stirring speed of 100 r / min, resulting in a back layer slurry viscosity of 5-10 seconds. First, the entire module is immersed in back layer 1 slurry for coating. After removing the entire module from back layer 1 slurry, it is sanded with 40-70 mesh bauxite sand and dried in a constant temperature and humidity environment (temperature 23±3℃, humidity 60±5%) for 12 hours. Then, the module is immersed in back layer 2 slurry for coating. After removing the entire module from back layer 2 slurry, it is sanded with 30-60 mesh bauxite sand and dried in a constant temperature and humidity environment (temperature 23±3℃, humidity 60±5%). Dry in a constant temperature and humidity environment (23±3℃, 60±5) for 12 hours; then immerse the module in the back layer 3 slurry for coating, remove the entire module from the back layer 3 slurry, and perform sanding operation with 16-30 mesh bauxite sand, and dry in a constant temperature and humidity environment (temperature 23±3℃, humidity 60±5) for 12 hours; repeat the back layer coating and sanding operation 3-6 times, and then dry in an environment of 23±3℃ and 60±5 for 12 hours to obtain the final back layer shell.

[0011] Step (5) Sealing: Using silica sol as a binder, the silica sol is mixed with 200-300 mesh bauxite powder at a solid-liquid ratio of 1.5-2.5:1. The mixture is stirred for 1 hour at a stirring speed of 100 r / min and the viscosity of the slurry is 5-10 seconds to obtain the sealing layer slurry. Then, the back shell obtained in step (4) is immersed in the sealing layer slurry for coating. After being removed and dried and hardened for 24 hours, the preparation of the shell sealing layer is completed.

[0012] Step (6) Calcination: The sealing layer shell prepared in step (5) is first dewaxed at a temperature of 300-400℃ for 30 minutes. After dewaxing, it is stored for 2-6 hours and then placed in a box-type electric calcination furnace at a calcination temperature of 1050±10℃ for 2-6 hours to obtain the shell of the zirconium-niobium alloy artificial joint prosthesis.

[0013] In the steps described above, the parameters of the binder silica sol are: SiO2 mass percentage 20-30%, specific gravity 1.32 g / cm³. 3 pH value: 9.7-10.5, colloidal particle size: 8-12nm.

[0014] The operation described in step (4) is repeated 6-8 times by coating, sprinkling sand and drying hardening in the backing slurry.

[0015] This invention selects yttrium oxide as the surface refractory material, zirconium acetate and ammonium metatungstate as binders to prepare a yttrium oxide surface shell system, and selects bauxite sand and bauxite powder as the back refractory material, and uses silica sol as a binder to prepare a back shell system.

[0016] Compared with the prior art, the present invention has the following technical effects.

[0017] (1) This invention studies the proportion and amount of adhesive, etc., and obtains a shell strength that can withstand the high melting point of zirconium-niobium alloy through experiments. Through the experiment of the surface layer slurry, it can be seen that the shell surface layer we made will not react with the zirconium-niobium alloy surface, which also meets the high surface requirements of medical implants, thus laying a good foundation for the melting and casting of artificial joint prosthesis shells.

[0018] (2) This invention reveals the possibility of using investment casting to prepare a mold shell and cast a perfect product, which helps artificial joints to move towards high-end development. Attached Figure Description

[0019] Figure 1 A comparison of the high-temperature strength of the shells in three examples.

[0020] Figure 2 A comparison of shell fracture loads for three examples. Detailed Implementation

[0021] The present invention will now be described in detail with reference to specific embodiments. Example 1

[0022] A method for preparing an investment casting mold shell for a zirconium-niobium alloy artificial joint prosthesis includes the following steps.

[0023] Step (1) Wax mold cleaning: Clean the assembled wax mold assembly with methyl ethyl ketone and then with a penetrant. Before pouring the surface slurry, use a high-pressure air gun to blow air into areas with excessive solution to avoid liquid accumulation in these areas. After cleaning, the mold assembly should be left to dry for 24 hours.

[0024] Step (2) Surface layer: First, prepare the binder in the following ratio by mass: deionized water: zirconium acetate: ammonium metatungstate (0.8:1.6:4.5). After preparing these three solutions, add 1% high-purity boric acid by mass. Mix the binder mixture and stir every 3 hours to ensure the powder is completely dissolved in the solution. The binder should be transparent with no powder suspended on the liquid surface. Let it stand for 24 hours in a closed and dry environment. Then, mix the 24-hour-standing binder with yttrium oxide powder (34... Mix the slurry (0 mesh) with a solid-liquid ratio of 2.5:1. Add 2ml / 30kg of rapid penetrant and 2ml / 30kg of defoamer n-octanol according to the ratio. Stir at 480 rpm. After stirring, vacuum treatment is performed. The viscosity of the surface slurry is 21 seconds, and the effective lifespan of the surface slurry is 60 minutes. After the slurry is coated with wax mold, 60-80 mesh yttrium oxide sand is used for sanding. Then, after drying at constant temperature and humidity (23℃, 70%) for 24 hours, the surface shell is obtained.

[0025] Step (3) Facing layer: The bonding agent ratio of the facing layer is deionized water: zirconium acetate: ammonium metatungstate (0.8:1.6:4.5 by mass). After mixing the bonding agent ratio, stir once every 3 hours to make the powder completely dissolve in the solution. The bonding agent is transparent and no powder is suspended on the liquid surface. Let it stand for 24 hours in a closed and dry environment. Mix the binder that has been left to stand for 24 hours with yttrium oxide powder (340 mesh), with a solid-liquid ratio of 0.8:1. Add 2 ml of n-octanol (a defoamer) per 30 kg of water and rotate the mixture at a combination of high and low speeds at 320 rpm to bring the slurry temperature to above 25°C. The operating environment should be above 25°C. The slurry viscosity should be 8 seconds. After 60 minutes, the viscosity should increase. Add binder to reduce the viscosity. The effective shelf life under refrigeration is 12 hours. After the slurry is coated onto the module, use 40-70 mesh yttrium oxide sand for sanding. Then, dry the mixture at a constant temperature and humidity of 23°C and 60% for 24 hours to obtain the surface shell.

[0026] Step (4) Backing Layer: The adhesive ratio for backing layers 1 and 2 is alcohol:ethyl silicate:hydrochloric acid (5.6L:5.6L:100ml). After mixing the adhesives, let them stand for 48 hours in a closed and dry environment. The solid-liquid ratio of the backing layer slurry is 0.8:1. Backing layers 1 and 2 are made by first mixing the ethyl silicate adhesive that has been standing for 48 hours with bauxite powder (200 mesh), stirring in a mixer for 1 hour at a stirring speed of 100r / min, and achieving a slurry viscosity of 5 seconds. For back layer 3 and beyond, silica sol is used as the binder, with a solid-liquid ratio of 1.5:1. The prepared silica sol is mixed with bauxite powder (200 mesh), stirred for 1 hour at 100 rpm, resulting in a slurry viscosity of 8 seconds. The slurry coats the entire module. After removing the module from the back layer 1 slurry, 40-70 mesh bauxite sand is used for sanding. The module is then dried for 12 hours under constant temperature and humidity (23℃, 60%). Next, the module is immersed in the back layer 2 slurry for coating. After removing the module from the back layer 2 slurry, 40-70 mesh bauxite sand is used for sanding. 30-60 mesh bauxite sand is used for sand spreading and dried in a constant temperature and humidity environment (23℃, 60%) for 12 hours. The module is then immersed in the back layer 3 slurry for coating. After being removed from the back layer 3 slurry, 16-30 mesh bauxite sand is used for sand spreading and dried in a constant temperature and humidity environment (23℃, 60%) for 12 hours. The back layer coating and sand spreading operation is repeated 4 times. After that, the final back layer shell is obtained after drying in a constant temperature and humidity environment (23℃, 60%) for 12 hours.

[0027] Step (5) Sealing: Use silica sol as a binder, the solid-liquid ratio of the slurry is 1.5:1, mix the prepared silica sol with bauxite powder (200 mesh), stir for 1 hour with a stirring speed of 100 r / min, and the slurry viscosity is 8 seconds to obtain the sealing layer slurry; then immerse the back shell obtained in step (4) into the sealing layer slurry for coating, and after drying and hardening for 24 hours, the preparation of the shell sealing layer is completed.

[0028] Step (6) Calcination: The sealing layer shell prepared in step (5) is first dewaxed at 300℃ for 30 minutes. After dewaxing, it is stored for 2 hours and then placed in a box-type electric calcination furnace. The calcination temperature is selected as 1050℃ and calcination is carried out for 2 hours to obtain the shell of the zirconium-niobium alloy artificial joint prosthesis. Example 2

[0029] A method for preparing an investment casting mold shell for a zirconium-niobium alloy artificial joint prosthesis includes the following steps.

[0030] Step (1) Wax mold cleaning: Clean the assembled wax mold assembly with methyl ethyl ketone and then with a penetrant. Before pouring the surface slurry, use a high-pressure air gun to blow air into areas with excessive solution to avoid liquid accumulation in these areas. After cleaning, the mold assembly should be left to dry for 24 hours.

[0031] Step (2) Surface layer: First, prepare the binder in the following ratio by mass: deionized water: zirconium acetate: ammonium metatungstate (0.9:1.6:4.5). After preparing these three solutions, add 1% high-purity boric acid by mass. Mix the binder mixture and stir every 3 hours to ensure the powder is completely dissolved in the solution. The binder should be transparent with no powder suspended on the liquid surface. Let it stand for 24 hours in a closed and dry environment. Then, mix the 24-hour-standing binder with yttrium oxide powder (34... Mix the slurry (0 mesh) with a solid-liquid ratio of 2.6:1. Add 2ml / 30kg of rapid penetrant and 2ml / 30kg of defoamer n-octanol according to the ratio. Stir at 480 rpm. After stirring, vacuum treatment is performed. The viscosity of the surface slurry is 21 seconds, and the effective lifespan of the surface slurry is 60 minutes. After the slurry is coated with wax mold, 60-80 mesh yttrium oxide sand is used for sanding. Then, after drying at constant temperature and humidity (23℃, 70% humidity) for 24 hours, the surface shell is obtained.

[0032] Step (3) Facing layer: The bonding agent ratio of the facing layer is deionized water: zirconium acetate: ammonium metatungstate (0.9:1.6:4.5 by mass). After mixing the bonding agent ratio, stir it once every 3 hours to make the powder completely dissolve in the solution. The bonding agent is transparent and no powder is suspended on the liquid surface. Let it stand for 24 hours in a closed and dry environment. Mix the binder that has been left to stand for 24 hours with yttrium oxide powder (340 mesh), with a solid-liquid ratio of 0.9:1. Add 2 ml of n-octanol (30 kg) as defoamer and rotate the mixture at a combination of high and low speeds at 320 rpm to bring the slurry temperature to above 25°C. The operating environment should also be above 25°C. The slurry viscosity is 8 seconds. After 60 minutes, the viscosity increases. Add binder to reduce the viscosity. The effective refrigeration life is 12 hours. After the slurry is coated onto the module, use 40-70 mesh yttrium oxide sand for sanding. Then, dry the mixture at a constant temperature and humidity of 23°C and 60% for 24 hours to obtain the face shell.

[0033] Step (4) Backing Layer: The adhesive ratio for backing layer 1 and backing layer 2 is alcohol:ethyl silicate:hydrochloric acid (5.7L:5.7L:100ml). After mixing the adhesives, let them stand for 48 hours in a closed and dry environment. The solid-liquid ratio of the backing layer slurry is 0.9:1. Backing layer 1 and backing layer 2 slurries are made by first mixing the ethyl silicate adhesive that has been standing for 48 hours with bauxite powder (200 mesh), stirring in a mixer for 1 hour at a stirring speed of 100r / min, and achieving a slurry viscosity of 5 seconds. For back layer 3 and beyond, silica sol is used as the binder, with a solid-liquid ratio of 1.6:1. The prepared silica sol is mixed with bauxite powder (200 mesh), stirred for 1 hour at 100 rpm, resulting in a slurry viscosity of 8 seconds. The slurry coats the entire module. After removing the module from the back layer 1 slurry, 40-70 mesh bauxite sand is used for sanding. The module is then dried for 12 hours under constant temperature and humidity (23℃, 60%). Next, the module is immersed in the back layer 2 slurry for coating. After removing the module from the back layer 2 slurry, 40-70 mesh bauxite sand is used for sanding. 30-60 mesh bauxite sand is used for sand spreading and dried in a constant temperature and humidity environment (23℃, 60%) for 12 hours. The module is then immersed in the back layer 3 slurry for coating. After being removed from the back layer 3 slurry, 16-30 mesh bauxite sand is used for sand spreading and dried in a constant temperature and humidity environment (23℃, 60%) for 12 hours. The back layer coating and sand spreading operation is repeated 4 times. After that, the final back layer shell is obtained after drying in a constant temperature and humidity environment (23℃, 60%) for 12 hours.

[0034] Step (5) Sealing: Use silica sol as a binder, the solid-liquid ratio of the slurry is 1.6:1, mix the prepared silica sol with bauxite powder (200 mesh), stir for 1 hour with a stirring speed of 100 r / min, and the slurry viscosity is 8 seconds to obtain the sealing layer slurry; then immerse the back shell obtained in step (4) into the sealing layer slurry for coating, and after drying and hardening for 24 hours, the preparation of the shell sealing layer is completed.

[0035] Step (6) Calcination: The sealing layer shell prepared in step (5) is first dewaxed at 300℃ for 30 minutes. After dewaxing, it is stored for 2 hours and then placed in a box-type electric calcination furnace. The calcination temperature is selected as 1050℃ and calcination is carried out for 2 hours to obtain the shell of the zirconium-niobium alloy artificial joint prosthesis. Example 3

[0036] A method for preparing an investment casting mold shell for a zirconium-niobium alloy artificial joint prosthesis includes the following steps.

[0037] Step (1) Wax mold cleaning: Clean the assembled wax mold assembly with methyl ethyl ketone and then with a penetrant. Before pouring the surface slurry, use a high-pressure air gun to blow air into areas with excessive solution to avoid liquid accumulation in these areas. After cleaning, the mold assembly should be left to dry for 24 hours.

[0038] Step (2) Surface layer: First, prepare the binder in the following ratio by mass: deionized water: zirconium acetate: ammonium metatungstate (1.0:1.6:4.5). After preparing these three solutions, add 1% high-purity boric acid by mass. Mix the binder mixture and stir every 3 hours to ensure the powder is completely dissolved in the solution. The binder should be transparent with no powder suspended on the liquid surface. Let it stand for 24 hours in a closed and dry environment. Then, mix the 24-hour-standing binder with yttrium oxide powder (34... Mix the slurry (0 mesh) with a solid-liquid ratio of 2.7:1. Add 2ml / 30kg of rapid penetrant and 2ml / 30kg of defoamer n-octanol according to the ratio. Stir at 480 rpm. After stirring, vacuum treatment is performed. The viscosity of the surface slurry is 21 seconds, and the effective lifespan of the surface slurry is 60 minutes. After the slurry is coated with wax mold, 60-80 mesh yttrium oxide sand is used for sanding. Then, after drying at constant temperature and humidity (23℃, 70%) for 24 hours, the surface shell is obtained.

[0039] Step (3) Facing layer: The bonding agent ratio of the facing layer is deionized water: zirconium acetate: ammonium metatungstate (1.0:1.6:4.5 by mass). After mixing the bonding agent ratio, stir once every 3 hours to make the powder completely dissolve in the solution. The bonding agent is transparent and no powder is suspended on the liquid surface. Let it stand for 24 hours in a closed and dry environment. Mix the binder that has been left to stand for 24 hours with yttrium oxide powder (340 mesh), with a solid-liquid ratio of 1.0:1. Add 2 ml of n-octanol (30 kg) as defoamer and rotate and stir at a combination of high and low speeds at 320 rpm to bring the slurry temperature to above 25°C. The operating environment should also be above 25°C. The slurry viscosity is 8 seconds. After 60 minutes, the viscosity increases. Add binder to reduce the viscosity. The effective refrigeration life is 12 hours. After the slurry is coated onto the module, use 40-70 mesh yttrium oxide sand for sanding. Then, dry at a constant temperature and humidity of 23°C and 60% for 24 hours to obtain the face shell.

[0040] Step (4) Backing Layer: The adhesive ratio for backing layer 1 and backing layer 2 is alcohol:ethyl silicate:hydrochloric acid (5.8L:5.8L:100ml). After mixing the adhesives, let them stand for 48 hours in a closed and dry environment. The solid-liquid ratio of the backing layer slurry is 1.0:1. Backing layer 1 and backing layer 2 slurries are made by first mixing the ethyl silicate adhesive that has been standing for 48 hours with bauxite powder (200 mesh), stirring in a mixer for 1 hour at a stirring speed of 100r / min, and achieving a slurry viscosity of 5 seconds. For back layer 3 and beyond, silica sol is used as the binder, with a solid-liquid ratio of 1.7:1. The prepared silica sol is mixed with bauxite powder (200 mesh), stirred for 1 hour at 100 rpm, resulting in a slurry viscosity of 8 seconds. The slurry is applied to the entire module. After removing the module from the back layer 1 slurry, 40-70 mesh bauxite sand is used for sanding. The module is then dried for 12 hours under constant temperature and humidity (23℃, 60%). Next, the module is immersed in the back layer 2 slurry for coating. After removing the module from the back layer 2 slurry, 40-70 mesh bauxite sand is used for sanding. 30-60 mesh bauxite sand is used for sand spreading and dried in a constant temperature and humidity environment (23℃, 60%) for 12 hours. The module is then immersed in the back layer 3 slurry for coating. After being removed from the back layer 3 slurry, 16-30 mesh bauxite sand is used for sand spreading and dried in a constant temperature and humidity environment (23℃, 60%) for 12 hours. The back layer coating and sand spreading operation is repeated 4 times. After that, the final back layer shell is obtained after drying in a constant temperature and humidity environment (23℃, 60%) for 12 hours.

[0041] Step (5) Sealing: Use silica sol as a binder, the solid-liquid ratio of the slurry is 1.7:1, mix the prepared silica sol with bauxite powder (200 mesh), stir for 1 hour with a stirring speed of 100 r / min, and the slurry viscosity is 8 seconds to obtain the sealing layer slurry; then immerse the back shell obtained in step (4) into the sealing layer slurry for coating, and after drying and hardening for 24 hours, the preparation of the shell sealing layer is completed.

[0042] Step (6) Calcination: The sealing layer shell prepared in step (5) is first dewaxed at 300℃ for 30 minutes. After dewaxing, it is stored for 2 hours and then placed in a box-type electric calcination furnace. The calcination temperature is selected as 1050℃ and calcination is carried out for 2 hours to obtain the shell of the zirconium-niobium alloy artificial joint prosthesis.

[0043] The above comparison results show that, under the condition that other parameters are the same, three different binder ratios and slurry ratios were tested, resulting in three different shell molds. In the subsequent melting and casting process, we also ensured the consistency of experimental conditions. This was achieved by analyzing the cast products, the degree of deformation and cracking of the shell molds after casting, and... Figure 1 , Figure 2Analysis of the high-temperature strength and fracture load data of the mold shells revealed that the deformation and cracking of the mold shells in the three examples were relatively small, the product quality was good, the trend of the changes in high-temperature strength and fracture load was the same, and each product was able to fill the mold perfectly. Therefore, it can be determined that the proportions and operating methods in the patent application can be used to produce more investment casting mold shells suitable for the production of zirconium-niobium alloy artificial joint prostheses.

[0044] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention without departing from the principle of the present invention.

Claims

1. A method for preparing a zirconium-niobium alloy artificial joint prosthesis investment casting mold shell, characterized in that: Includes the following steps: (1) Wax mold cleaning: The assembled wax mold assembly is first cleaned with methyl ethyl ketone and then cleaned with a penetrant. Before pouring the surface slurry, the area with excessive solution should be blown with a high-pressure air gun to avoid liquid accumulation in the area. After cleaning, the assembly is left to dry for 24 hours. (2) Surface layer: The surface layer adhesive is prepared according to the mass ratio of deionized water: zirconium acetate: ammonium metatungstate of 0.5-1.5:1.0-2.0:4.0-5.

0. After preparing these three solutions, add 0.5-2 wt.% of high-purity boric acid. Mix the adhesive according to the ratio and stir every 3 hours to ensure that the powder is completely dissolved in the solution. The adhesive should be transparent with no powder suspended on the liquid surface. Let it stand for 24 hours in a closed and dry environment. Then, mix the mixed adhesive that has stood for 24 hours with 3 Yttrium oxide powder of 00-400 mesh is mixed, and the solid-liquid ratio of the slurry is 2.0-3.0:

1. 2ml / 30kg of rapid penetrant and 2ml / 30kg of defoamer n-octanol are added. The mixture is then stirred by rotary stirring and vacuumed. The resulting surface slurry has a viscosity of 21-23 seconds and an effective lifespan of 30-60 minutes. After the slurry is coated with a wax mold, 60-80 mesh yttrium oxide sand is sprinkled on the surface. The mixture is then dried for 24 hours at a temperature of 23±3℃ and a humidity of 70±5% to obtain the surface shell. (3) Facing layer: The bonding agent for the facing layer is prepared according to the mass ratio of deionized water: zirconium acetate: ammonium metatungstate of 0.8-2.0:1.0-2.0:4.0-5.

0. After mixing the bonding agent according to the ratio, it is stirred once every 3 hours to make the powder completely dissolved in the solution. The bonding agent is transparent and no powder is suspended on the liquid surface. It is then left to stand for 24 hours in a closed and dry environment. The bonding agent is mixed with 300-400 mesh yttrium oxide powder. The solid-liquid ratio of the slurry is 0.8-2.0:

1. 2 ml / 30 kg of defoamer n-octanol is added. The mixture is stirred by rotating at high speed and low speed. The viscosity of the resulting facing layer slurry is 8-10 seconds and the effective refrigeration life is 12 hours. After the slurry is coated onto the module, 40-70 mesh yttrium oxide sand is sprinkled on the facing layer. Then, the facing layer shell is obtained after drying for 24 hours at a temperature of 23±3℃ and a humidity of 60±5. (4) Backing layer: The adhesive ratio for backing layer 1 and backing layer 2 is 5.0-6.0L:5.0-6.0L:100ml by mass of alcohol:ethyl silicate:hydrochloric acid. After mixing the adhesives according to the ratio, they are left to stand for 48 hours in a closed and dry environment. The solid-liquid ratio of the slurry for backing layer 1 and backing layer 2 is 0.5-1.5:0.5-1.

5. The slurry for backing layer 1 and backing layer 2 is made by mixing the ethyl silicate adhesive that has been left to stand for 48 hours with 200- Mix 300-mesh bauxite powder and stir for 1 hour at a stirring speed of 100 rpm. The viscosity of the back layer 1 and back layer 2 slurry should be 3-5 seconds. For back layer 3 and subsequent back layers, use silica sol as a binder. The solid-liquid ratio of the slurry should be 1.5-2.5:

1. Mix the prepared silica sol with 200-300 mesh bauxite powder and stir for 1 hour at a stirring speed of 100 rpm. The viscosity of the back layer slurry should be 5-10 seconds. First, apply the entire mold... The module is immersed in the back layer 1 slurry for coating. After the entire module is removed from the back layer 1 slurry, it is sanded with 40-70 mesh bauxite sand and dried for 12 hours at a temperature of 23±3℃ and a humidity of 60±5%. Then, the module is immersed in the back layer 2 slurry for coating. After the entire module is removed from the back layer 2 slurry, it is sanded with 30-60 mesh bauxite sand and dried for 12 hours at a temperature of 23±3℃ and a humidity of 60±5%. Then, the module is immersed in the back layer 3 slurry for coating. After the entire module is removed from the back layer 3 slurry, it is sanded with 16-30 mesh bauxite sand and dried for 12 hours at a temperature of 23±3℃ and a humidity of 60±5%. The subsequent back layer coating, sanding and drying operations are repeated 3-6 times for the back layer 3 operation. After drying for 12 hours at a temperature of 23±3℃ and a humidity of 60±5, the final back layer shell is obtained. (5) Sealing: Using silica sol as a binder, the silica sol is mixed with 200-300 mesh bauxite powder at a solid-liquid ratio of 1.5-2.5:

1. The mixture is stirred for 1 hour at a stirring speed of 100 r / min and the viscosity of the slurry is 5-10 seconds to obtain the sealing layer slurry. Then, the back shell obtained in step (4) is immersed in the sealing layer slurry for coating. After being removed and dried and hardened for 24 hours, the preparation of the shell sealing layer is completed. (6) Calcination: The sealing layer shell prepared in step (5) is first dewaxed at a temperature of 300-400℃ for 30 minutes. After dewaxing, it is stored for 2-6 hours and then placed in a box-type electric calcination furnace at a calcination temperature of 1050±10℃ for 2-6 hours to obtain the shell of the zirconium-niobium alloy artificial joint prosthesis.

2. The method for preparing the investment casting mold shell of a zirconium-niobium alloy artificial joint prosthesis according to claim 1, characterized in that: The parameters of the binder silica sol are: SiO2 mass percentage 20-30%, specific gravity 1.32 g / cm³. 3 pH value: 9.7-10.5, colloidal particle size: 8-12nm.

3. The method for preparing the investment casting mold shell of a zirconium-niobium alloy artificial joint prosthesis according to claim 1, characterized in that: The operation described in step (4) is repeated 6-8 times in the backing slurry, including coating, sprinkling sand and drying and hardening.

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