CN1306059C - Process for preparing nano coating by plasma spraying - Google Patents

Abstract

The present invention provides a method for spraying and preparing a nano coating by plasma. Transportation gas is used for directly injecting coating materials into plasma flames, the coating materials are heated and melted by the high temperature of the plasma flames, the material surfaces adhering on a metal base are struck at high speed, and the nano coating is prepared by cooling. The present invention is characterized in that the coating materials are prepared nano grade slurry, the grain size of the coating materials in the slurry is smaller than or equal to 250 nm, and a weight percentage content is from 5 to 20%. When the plasma flames are injected, the nano grade slurry is atomized. The method for spraying and preparing a nano coating by plasma provided by the present invention can greatly improve bonding strength and crack extension preventing capability between the coating and the basic metal materials, satisfies the requirements of manufacturing an implantation body with long life, and can also endow the coating with the various excellent characteristics of nano materials. At the same time, the present invention has the advantages of simple methods, maturation, easy operation and high efficiency.

Description

Method for preparing nano-coating by plasma spraying

1. Technical field

The invention belongs to the technical field of medical material compounding, and in particular relates to a method for preparing a nano-coating by plasma spraying.

2. Background technology

Hydroxyapatite is the main inorganic part of human teeth and bone tissue. It has excellent biocompatibility and can form a firm chemical bond with bone and soft tissue. Therefore, hydroxyapatite ceramics are widely used for filling bone defects. wait. However, like most ceramic materials, bulk hydroxyapatite also has the brittleness of ceramics, and is prone to fatigue failure in physiological environments, so it can only be used for bone repair and replacement under no force or only positive pressure , cannot be used clinically as a complete load-bearing material.

As we all know, metals have excellent mechanical properties and have been widely used in clinic as load-bearing materials such as joints. However, due to the biological inertness of metal materials, they cannot form direct chemical bonds with human tissues such as bone. Therefore, when they are implanted in the body, a layer of fibrous film will often be formed between the bone tissue and the metal implant material, which exists for a long time. Can cause loosening, which can lead to plant failure.

In order to overcome the shortcomings brought about by using a single metal material or a single hydroxyapatite ceramic, people have designed a medical composite material with a metal material as the matrix material and a bioactive ceramic coating on the surface, so that the implant material has both metal and metal materials. Excellent mechanical properties, but also has the surface bioactivity of bioactive ceramics.

At present, there are many methods for preparing hydroxyapatite coating on the surface of metal materials, such as slurry sintering method, hot isostatic pressing method, electrophoresis method, ion sputtering method, high-speed spraying method, high-speed oxygen fuel coating method and plasma spraying method, etc. . Among them, the plasma spraying method uses high-temperature plasma at 5000-10000°C to heat and melt the hydroxyapatite coating material in a short period of time, and hits the surface of the metal base material at a supersonic speed of 300m/s to form a firm bond with the base material. combined. This method has been used for surface modification of artificial implants such as artificial hip joints and knee joints. Due to the high efficiency and high speed of coating preparation by this technology, it is easy to obtain coatings with a thickness of tens of microns to hundreds of microns, so that the stress borne by the metal base material can be well transmitted in the coating through the metal-ceramic interface. Overcoming the brittleness of ceramics, and the plasma spraying technology can be used for mass production, so the restoration of this composite material will soon be widely used clinically. However, due to the particle size of the hydroxyapatite coating material used in the conventional plasma spraying method is micron-scale, the particles are relatively large, the bonding strength between the coating and the base metal material is poor, and the coating is prone to fatigue damage and peeling off, which cannot meet the production requirements. Long-lived implant requirements. Therefore, improving the bonding strength between the hydroxyapatite coating and the base metal material has always been a hot and difficult issue in the research of medical coating materials.

3. Contents of the invention

The task of the present invention is to provide a new method for preparing nano-coatings by plasma spraying in view of the problems existing in the prior art, so that the coatings can obtain the excellent properties of nano-materials and improve the bonding strength between coatings and base metal materials , to meet the requirements of making long-life implants.

The method for preparing nano-coating by plasma spraying provided by the present invention is to directly inject the coating material into the plasma flame by means of transport gas, and use the high temperature of the plasma flame to heat and melt the coating material, and then hit and adhere to the surface of the metal base material at a high speed. On the basis of the existing technology that has been formed, the coating material is changed into a configured nano-scale slurry, the particle size of the coating material in the slurry is ≤250nm, and its weight percentage content is 5-20%; when injected into the plasma flame, Atomize the nanoscale slurry.

In the present invention, the micron-scale and dry powder coating materials used in the prior art are converted into nano-scale slurry for configuration. On the one hand, the nanoparticles of the coating material have a large interface, and the atomic arrangement of the interface does not have long-range order. , is relatively chaotic, and the atoms are easy to migrate under the condition of external force deformation, so that the internal stress of the prepared coating is reduced and evenly distributed, showing good toughness and certain ductility, thereby greatly improving the combination of the coating and the substrate Strength and crack growth resistance, overcome the shortcomings of the coatings obtained by conventional methods, which are prone to fatigue damage and peeling off, and improve the toughness of the coatings. Several particles are gathered together in clusters and cannot be dispersed, but they can be dispersed well when they are configured into a slurry in a dispersant. It is precisely because the coating material of the present invention adopts a well-dispersed slurry-like coating material that when the plasma flame is injected, the technical means of atomizing it can be adopted. Due to the atomization means, after atomization The coating material particles are more uniformly dispersed in the mist slurry, and the coating material particles themselves are nano-scale, and the content in the slurry is low, so when the atomized nano-scale slurry is injected into the plasma When the flame is on, most of the dispersant evaporates immediately, and the remaining small amount of coating material particles can be fully melted.

The nano-scale slurry used in the present invention is obtained by adding the nano-scale coating material into the dispersant water and vibrating with high-energy ultrasonic waves for 10 to 20 minutes. The nanoscale coating material can be powder or slurry with higher concentration. The coating material is selected from at least one of hydroxyapatite, aluminum oxide and titanium oxide. Compressed air is used for atomization, and its gauge pressure is 0.5 to 1 atmosphere.

The method for preparing nano-coatings by plasma spraying provided by the present invention not only greatly improves the bonding strength and crack propagation resistance between the coating and the base metal material, solves the hot and difficult problems in the research of medical coating materials, but also The coating can be endowed with various excellent properties possessed by nanomaterials, and at the same time, the method is simple, mature, easy to operate and high in efficiency.

4. Specific implementation

The present invention is specifically described and further illustrated by examples below. It is worth pointing out that the following examples cannot be interpreted as limiting the protection scope of the present invention, and some non-essential improvements and adjustments made by those skilled in the art according to the content of the present invention above still belong to the protection scope of the present invention.

Example 1

This example is the preparation of nano-hydroxyapatite coating.

(1) Using the wet process disclosed by Chen Junqiu, master's thesis of Sichuan University in 2000, to synthesize hydroxyapatite nano-slurry with particle size ≤ 250nm.

(2) adding the hydroxyapatite nano-slurry into the dispersant water to prepare the nano-slurry with 5% by weight of the hydroxyapatite. When configuring, use ultrasonic high-energy vibration for 10 minutes to achieve uniform dispersion.

(3) Pass the hydroxyapatite nano-slurry through a conventional sprayer, atomize it into a mist with compressed air with a gauge pressure of 0.5 atmospheres, inject it directly into the plasma flame, and use the high temperature of the flame to evaporate the water vapor immediately and The hydroxyapatite nanoparticles are melted, hit and adhere to the surface of the metal base material at high speed, and then cool rapidly to form a hydroxyapatite nano-coating. The plasma flame generator uses nitrogen as the working gas, the working voltage is 50-65 volts, the working current is 260-350 amperes, and the distance from the muzzle to the metal base material is 60±5cm.

Example 2

This example is the preparation of nano-hydroxyapatite coating.

(1) With embodiment 1, omission.

(2) adding the hydroxyapatite nano-slurry into the dispersant water to prepare the nano-slurry with 10% by weight of the hydroxyapatite. When configuring, use ultrasonic high-energy vibration for 15 minutes to achieve uniform dispersion.

(3) Pass the hydroxyapatite nano-slurry through a conventional sprayer, atomize it with compressed air with a gauge pressure of 0.8 atmospheres to form a mist, inject it directly into the plasma flame, and use the high temperature of the flame to evaporate the water vapor immediately and The hydroxyapatite nanoparticles are melted, hit and adhere to the surface of the metal base material at high speed, and then cool rapidly to form a hydroxyapatite nano-coating. The plasma flame generator uses nitrogen as the working gas, supplemented by hydrogen, the working voltage is 65-80 volts, the working current is 200-300 amperes, and the distance from the muzzle to the metal base material is 80±5cm. In addition, during the spraying process, the workpiece is cooled with compressed air at the same time.

Example 3

This example is the preparation of nano-hydroxyapatite coating.

(1) With embodiment 1, omission.

(2) adding the hydroxyapatite nano-slurry into the dispersant water to prepare the nano-slurry with 20% by weight of the hydroxyapatite. When configuring, use ultrasonic high-energy vibration for 20 minutes to achieve uniform dispersion.

(3) Pass the hydroxyapatite nano-slurry through a conventional sprayer, atomize it with compressed air with a gauge pressure of 1.0 atmospheric pressure to form a mist, inject it directly into the plasma flame, and use the high temperature of the flame to evaporate the water vapor immediately and The hydroxyapatite nanoparticles are melted, hit and adhere to the surface of the metal base material at high speed, and then cool rapidly to form a hydroxyapatite nano-coating. The plasma flame generator uses argon as the working gas, supplemented by hydrogen, the working voltage is 40-70 volts, the working current is 300-400 amperes, and the distance from the muzzle to the metal base material is 70±5cm. In addition, during the spraying process, the workpiece is cooled with compressed air at the same time.

Example 4

This example is the preparation of the mixed coating of nano-alumina and titanium oxide.

(1) Commercially available nano-scale aluminum oxide and titanium oxide slurry with a particle size of ≤250nm is configured into aluminum oxide and titanium oxide at a weight ratio of 1:1 according to the pure content of aluminum oxide and titanium oxide Mix the nanoslurries.

(2) Adding the mixed nano-slurry of aluminum oxide and titanium oxide into the dispersant water to prepare the nano-slurry with a weight percent content of 5%. When configuring, use ultrasonic high-energy vibration for 10 minutes to achieve uniform dispersion.

(3) Pass the mixed nano-slurry of aluminum oxide and titanium oxide through a conventional sprayer, atomize it with compressed air with a gauge pressure of 0.5 atmospheres to form a mist, inject it directly into the plasma flame, and use the high temperature of the flame to dissipate the water vapor Evaporate immediately and melt the mixed nanoparticles of aluminum oxide and titanium oxide. After hitting and adhering to the surface of the metal base material at high speed, it is rapidly cooled to form a mixed nano-coating of aluminum oxide and titanium oxide. The plasma flame generator uses argon as the working gas, the working voltage is 30-50 volts, the working current is 250-350 amperes, and the distance from the muzzle to the metal base material is 55±5cm.

Example 5

This example is the preparation of the mixed coating of nano-alumina and titanium oxide.

(1) Except that the aluminum oxide and titanium oxide added are based on pure content, and its weight ratio is 3: 7, all the other are the same as embodiment 4, omitted.

(2) Adding the mixed nano-slurry of aluminum oxide and titanium oxide into the dispersant water to prepare the nano-slurry with a weight percent content of 20%. When configuring, use ultrasonic high-energy vibration for 20 minutes to achieve uniform dispersion.

(3) Pass the mixed nano-slurry of aluminum oxide and titanium oxide through a conventional sprayer, atomize it with compressed air with a gauge pressure of 1.0 atmospheres to form a mist, inject it directly into the plasma flame, and use the high temperature of the flame to dissipate the water vapor Evaporate immediately and melt the mixed nanoparticles of aluminum oxide and titanium oxide. After hitting and adhering to the surface of the metal base material at high speed, it is rapidly cooled to form a mixed nano-coating of aluminum oxide and titanium oxide. The plasma flame generator uses argon as the working gas, supplemented by hydrogen, the working voltage is 40-70 volts, the working current is 300-400 amperes, and the distance from the muzzle to the metal base material is 70±5cm. In addition, during the spraying process, the workpiece is cooled with compressed air at the same time.

Example 6

This embodiment is the preparation of nano-titanium oxide coating.

(1) Adding commercially available titanium oxide nano-slurry with a particle diameter of ≤250nm into dispersant water to prepare a nano-slurry with a titanium oxide weight percent content of 5%. When configuring, use ultrasonic high-energy vibration for 10 minutes to achieve uniform dispersion.

(2) Pass the titanium oxide nano-slurry through a conventional sprayer, atomize it with compressed air with a gauge pressure of 0.5 atmospheres to form a mist, and inject it directly into the plasma flame, and use the high temperature of the flame to quickly evaporate the water vapor and remove the titanium oxide. The nanoparticles are melted, hit and adhered to the surface of the metal base material at high speed, and then cooled rapidly to form a titanium oxide nano-coating. The plasma flame generator uses argon as the working gas, the working voltage is 30-50 volts, the working current is 250-350 amperes, and the distance from the muzzle to the metal base material is 55±5cm.

Example 7

This embodiment is the preparation of nano-titanium oxide coating.

(1) With embodiment 1, omission.

(2) adding the titanium oxide nano-slurry into the dispersant water to prepare the nano-slurry with a titanium oxide weight percent content of 10%. When configuring, use ultrasonic high-energy vibration for 15 minutes to achieve uniform dispersion.

(3) Pass the titanium oxide nano-slurry through a conventional sprayer, atomize it with compressed air with a gauge pressure of 0.8 atmospheres to form a mist, inject it directly into the plasma flame, and use the high temperature of the flame to quickly evaporate the water vapor and remove the titanium oxide. The nanoparticles are melted, hit and adhered to the surface of the metal base material at high speed, and then cooled rapidly to form a titanium oxide nano-coating. The plasma flame generator uses nitrogen as the working gas, the working voltage is 50-65 volts, the working current is 260-350 amperes, and the distance from the muzzle to the metal base material is 65±5cm. In addition, during the spraying process, the workpiece is cooled with compressed air at the same time.

The ultrasonic instrument used in the above embodiments is the KQ-250B type produced by Kunming Ultrasonic Instrument Company; the plasma spraying machine used is the AR-2000 type produced by the American METCO company.

Claims (5)

1. A method for preparing a nano-coating by plasma spraying. The method is to directly inject the coating material into the plasma flame by means of transport gas, and use the high temperature of the plasma flame to heat and melt the coating material, and then hit and adhere to the surface of the metal base material at a high speed It is characterized in that the coating material is a nano-scale slurry configured, the particle size of the coating material in the slurry is ≤250nm, and the weight percentage content is 5-20%; when injecting the plasma flame, the nano-scale slurry Material atomization. 2. The method for preparing nano-coating by plasma spraying according to claim 1, characterized in that the nano-scale slurry is prepared by adding the nano-scale coating material into the dispersant water and oscillating with high-energy ultrasonic waves for 10-20 minutes. 3. The method for preparing nano-coating by plasma spraying according to claim 1 or 2, characterized in that the coating material is selected from at least one of hydroxyapatite, aluminum oxide and titanium oxide. 4. The method for preparing nano-coating by plasma spraying according to claim 1 or 2, characterized in that compressed air is used for atomization, and its gauge pressure is 0.5-1 atmosphere. 5. The method for preparing nano-coating by plasma spraying according to claim 3, characterized in that compressed air is used for atomization, and its gauge pressure is 0.5-1 atmosphere.