CN103239761A - Silicon-nitride-coated medical magnesium alloy material and preparation method thereof - Google Patents

Abstract

A silicon nitride-coated medical magnesium alloy material is composed of a magnesium alloy substrate and a silicon nitride coating attached to the surface; the preparation method is as follows: 1) after grinding, polishing and degreasing the magnesium alloy sample , carry out sand blasting treatment to remove surface scale, increase surface roughness and coating, and enhance the firmness of the magnesium alloy substrate and coating; 2) The magnesium alloy sample after the above treatment is enhanced by radio frequency plasma A deposition method or a particle beam deposition method is used to prepare a silicon nitride ceramic coating on the surface of a magnesium alloy sample. The advantages of the present invention are: the silicon nitride ceramic coating prepared on the surface of the magnesium alloy is compact, has a high bonding strength with the substrate, and improves the corrosion resistance of the magnesium alloy; the corrosion resistance of the coating can be adjusted by changing the _SiH4 ratio and deposition time Performance and degradation time; no harmful substances are used in the process of preparing the magnesium alloy coating, and it has the advantages of simple process, controllable coating, and no need for prefabricated film treatment of samples.

Description

A kind of silicon nitride coating medical magnesium alloy material and preparation method

technical field

The invention belongs to the field of biomedical materials, in particular to a silicon nitride-coated medical magnesium alloy material and a preparation method.

Background technique

At present, the medical metal materials in clinical application mainly include stainless steel, cobalt-based alloy, titanium alloy and so on. However, its elastic modulus is much higher than that of human bone, which will produce "stress shielding" during use, and the dissolution of harmful ions often leads to severe inflammatory reactions and tissue damage, resulting in implant failure. In particular, implanted alloys cannot be absorbed and degraded in the body, and must be taken out through a second operation after the wounded bone heals, which greatly increases the patient's economic and psychological burden and physical pain. Therefore, in bone injury surgery, the use of degradable materials to replace traditional medical metal materials has attracted more and more attention, and has become an international research frontier and hot spot in the field of biomaterials.

Biomedical degradable polymer materials such as PLLA and PGA have been used clinically, but due to their small elastic modulus, they can only be used in areas that are not bearing stress, and the degradation products are acidic and easy to cause aseptic inflammation, thus limiting Its wide application.

Magnesium or magnesium alloy is a metal material that can be degraded in the body environment. Compared with the above metal implant materials such as titanium alloy and stainless steel, its advantages are mainly manifested in: 1) The density of magnesium is 1.74g/cm ³ , and it is compatible with The compact bone density (1.80g/cm ³ ) of human bone is very close, its mechanical properties are closer to natural bone, and its moderate elastic modulus can effectively alleviate the stress shielding effect, which plays an important role in fracture healing and implant stability;2 ) Magnesium is an essential element for the human body, has biological activity, mediates osteogenesis, and biocompatibility. The total amount of magnesium in the human body is about 20 grams. During life, it can promote the formation of bones and cells, catalyze or activate more than 300 enzyme systems in the body, participate in energy metabolism in the body, and play a key role in the transportation, storage and utilization of energy. Function; 3) The standard equilibrium potential of magnesium is -2.34V, which is lower than other alloys, showing high chemical and electrochemical activity, and has its natural advantages as a degradable material; 4, rich in resources and low in price.

In summary, magnesium or magnesium alloys have the advantages of good medical safety, mechanical properties, controllable corrosion performance, and minimal side effects of degradation products, and are expected to develop into a new generation of biodegradable materials. However, in the corrosive environment where the human body is full of Cl ^- , magnesium and magnesium alloys will fail prematurely due to the faster degradation rate. Usually temporary implants require a service time of 3 months to 1 year. It can be estimated that the degradation rate of magnesium and magnesium alloys as implant materials should be controlled within 0.1mm/a, but the research found that the degradation rate of pure magnesium in simulated body fluids It is 0.2-1.0mm/a. In animal experiments, it is also found that the corrosion rate of pure magnesium is too fast, and a large amount of hydrogen gas is generated, which leads to premature failure of the material and limits its clinical application.

Therefore, in order to make magnesium or its alloys really used clinically, its corrosion resistance must be improved, and surface coating treatment is one of the methods to effectively improve the corrosion resistance of magnesium and magnesium alloys. Surface treatment of magnesium alloys with silicon nitride materials with good biocompatibility is an important way to effectively control the degradation rate of magnesium-based materials.

Contents of the invention

The purpose of the present invention is to address the above problems, to provide a silicon nitride coated medical magnesium alloy material and its preparation method, the material is firmly combined with the coating and the coating is dense, has good thermal stability and biological stability, and does not degrade The period can be regulated by coating thickness and hydrogen content, which is suitable for medium and long-term implant materials, especially in line with the clinical needs of orthopedic surgery.

Technical scheme of the present invention:

A silicon nitride coated medical magnesium alloy material is composed of a magnesium alloy substrate and a silicon nitride coating attached to the surface.

A kind of described silicon nitride coating medical magnesium alloy material is a preparation method, and the steps are as follows:

1) After grinding, polishing, and degreasing the magnesium alloy sample, perform sandblasting to remove surface oxide skin, increase surface roughness and coating, and enhance the firmness of the magnesium alloy substrate and coating;

2) Using the above-mentioned treated magnesium alloy sample to prepare a silicon nitride ceramic coating on the surface of the magnesium alloy sample by radio frequency plasma enhanced chemical vapor deposition method or particle beam deposition method.

The process parameters of the radio frequency plasma enhanced chemical vapor deposition method are as follows: the magnesium alloy sample is placed in the inner cavity deposition chamber of the radio frequency plasma enhanced chemical vapor deposition equipment, and the system is pumped to a vacuum degree of 1×10 ^-4 -1 ×10 ^-5 Pa, with SiH ₄ and NH ₃ or N ₂ mixed gas as the reaction gas source, deposition temperature at 150-450°C, RF power at 80-400W, deposition time at 10s-60min, after cooling A silicon nitride ceramic coating is prepared on the surface of the alloy.

The flow rate of SiH ₄ in the SiH ₄ and NH ₃ or N ₂ mixed gas is 10-100 sccm; the flow ratio of SiH ₄ and NH ₃ or N ₂ is 1: 0.2-1.

The process parameters of the particle beam deposition method are as follows: the magnesium alloy sample is placed in the particle beam deposition equipment, with bulk silicon nitride as the target material, and the vacuum degree is 1×10 ^-4 -1×10 ^-5 Pa Next, after bombardment with argon ions, heat treatment at high temperature, the bombardment voltage of argon ions is 10-100KeV, the density of argon ions is (1-5)×10 ¹⁶ ions/cm ³ , the heat treatment temperature is 200-450°C, and the heat treatment time is 2 -12h.

The present invention has the following advantages and positive effects:

1) The silicon nitride ceramic coating prepared on the surface of the magnesium alloy is dense and has a strong bond with the substrate, which improves the corrosion resistance of the magnesium alloy;

2) The corrosion resistance and degradation time of the coating can be adjusted by changing the SiH ₄ ratio and deposition time;

3) There is no use of harmful substances in the process of preparing the magnesium alloy coating, and it has the advantages of simple process, controllable coating, and no need for prefabricated film treatment of samples.

Description of drawings

The accompanying drawing shows the polarization curves of AZ31 magnesium alloys with silicon nitride coating and uncoated AZ31 magnesium alloys in simulated body fluids on the surface of AZ31 magnesium alloys in different ways.

Detailed ways

The present invention will be further described below in conjunction with the examples.

Example 1:

A silicon nitride coating medical magnesium alloy material is a preparation method, the steps are as follows:

1) Grind the AZ91D magnesium alloy substrate, polish it on a PG-1 polishing machine, cut it into a sample with a length of 10 mm, a width of 10 mm, and a thickness of 2 mm, ultrasonically clean it in acetone solution for 10 minutes, and then ultrasonically clean it in ethanol for 10 minutes. Finally, it was ultrasonically cleaned in deionized water for 10 minutes, and then sandblasted for 3 minutes after drying;

2) Put the above-mentioned magnesium alloy sheet into the RF-PECVD plasma chemical vapor deposition station, with the deposition side facing up, evacuate the system to a vacuum of 1×10 ^-5 Pa, set the temperature at 250°C, and the frequency at 13.56MHz, and turn on Heater, start deposition when the temperature of the deposition chamber is stable at 250°C. The selected radio frequency power is 200w, by adjusting the mass flow meter (MFC) so that the flow of silane and ammonia are respectively SiH ₄ and N ₂ The flow rate is 50 sccm and 10 sccm respectively, after deposition for 5min, turn off the reaction gas source, radio frequency source and heating The device was used to stop the deposition, and the sample was taken out after cooling to obtain a uniform and dense silicon nitride coating.

The polarization curves of the silicon nitride coating and the uncoated simulated body fluid are as shown in the attached figure, which shows that: the silicon nitride coating adopts this method, the polarization potential of the sample increases, and the corrosion resistance Enhancement, demonstrating the effectiveness of silicon nitride coatings in increasing the corrosion resistance of magnesium alloy substrates.

Example 2:

A silicon nitride coating medical magnesium alloy material is a preparation method, the steps are as follows:

1) Grind the AZ31 magnesium alloy substrate, polish it on a PG-1 polishing machine, cut it into a sample with a length of 10mm, a width of 10mm, and a thickness of 2mm, ultrasonically clean and remove oil in acetone for 10min, then ultrasonically clean in ethanol for 10min, and finally Ultrasonic cleaning in deionized water for 10 minutes, followed by sandblasting for 3 minutes after drying;

2) Put the above-mentioned magnesium alloy sheet into the inner cavity deposition chamber of the RF-PECVD equipment, pump the system to a vacuum of 1×10 ^-4 , set the temperature at 300°C, turn on the heater, and wait until the temperature of the deposition chamber is stabilized at 300°C start to deposit. The selected radio frequency power is 80W, and the flow rates of silane and ammonia are respectively 30 sccm and 10 sccm by adjusting a mass flow meter (MFC). After the deposition time reaches 5 minutes, turn off the reaction gas source, the radio frequency source and the heater, stop the deposition, and take out the alloy sheet after cooling to obtain a uniform and dense silicon nitride coating.

The polarization curves of the silicon nitride coating and the uncoated simulated body fluid are as shown in the attached figure, which shows that: the silicon nitride coating adopts this method, the polarization potential of the sample increases, and the corrosion resistance Enhancement, demonstrating the effectiveness of silicon nitride coatings in increasing the corrosion resistance of magnesium alloy substrates.

Example 3:

A silicon nitride coating medical magnesium alloy material is a preparation method, the steps are as follows:

1) Grind the AZ31 magnesium alloy substrate, polish it on a PG-1 polishing machine, cut it into a sample with a length of 10mm, a width of 10mm, and a thickness of 2mm, ultrasonically clean and remove oil in acetone for 10min, then ultrasonically clean in ethanol for 10min, and finally Ultrasonic cleaning in deionized water for 10 minutes, followed by sandblasting for 3 minutes after drying;

2) Put the magnesium alloy sample into the particle beam deposition equipment, use bulk silicon nitride as the target, and bombard it with argon ions at a vacuum of 1×10 ^-5 Pa, then heat it at high temperature, and the argon ion bombardment voltage At 60KeV, the density of argon ions is 3×10 ¹⁶ ions/cm ³ . Put the magnesium alloy sample bombarded by argon ions into a high-temperature furnace, heat it to 300°C, keep it for 2 hours, and obtain a uniform and dense Silicon nitride coating.

The polarization curves of the silicon nitride coating and the uncoated simulated body fluid are as shown in the attached figure, which shows that: the silicon nitride coating adopts this method, the polarization potential of the sample increases, and the corrosion resistance Enhancement, demonstrating the effectiveness of silicon nitride coatings in increasing the corrosion resistance of magnesium alloy substrates.

Claims (5)

1. A silicon nitride coating medical magnesium alloy material, characterized in that: it is made of a magnesium alloy base material and a silicon nitride coating attached on its surface. 2. a silicon nitride coating medical magnesium alloy material as claimed in claim 1 is a preparation method, characterized in that the steps are as follows: 1) After grinding, polishing, and degreasing the magnesium alloy sample, perform sandblasting to remove surface oxide skin, increase surface roughness and coating, and enhance the firmness of the magnesium alloy substrate and coating; 2) Using the above-mentioned treated magnesium alloy sample to prepare a silicon nitride ceramic coating on the surface of the magnesium alloy sample by radio frequency plasma enhanced chemical vapor deposition method or particle beam deposition method. 3. according to the described silicon nitride coating medical magnesium alloy material of claim 2 is preparation method, it is characterized in that: the process parameter of described radio frequency plasma enhanced chemical vapor deposition method is: put magnesium alloy sample into radio frequency plasma In the inner cavity deposition chamber of the enhanced chemical vapor deposition equipment, the system is evacuated to a vacuum of 1×10 ^-4 -1×10 ^-5 Pa, with SiH ₄ and NH ₃ or N ₂ mixed gas as the reaction gas source, and the deposition temperature is Under the conditions of 150-450°C and radio frequency power of 80-400W, the deposition time is 10s-60min, and silicon nitride ceramic coating is prepared on the alloy surface after cooling. 4. according to the described silicon nitride coating medical magnesium alloy material of claim 2 is preparation method, it is characterized in that: described SiH ₄ and NH ₃ or N ₂ The flow rate of SiH ₄ in the mixed gas is 10-100sccm; SiH ₄ and NH ₃ or N ₂ flow ratio l: 0.2-1. 5. according to the described silicon nitride coating medical magnesium alloy material of claim 2 is preparation method, it is characterized in that: the process parameter of described particle beam deposition method is: magnesium alloy sample is put into particle beam deposition equipment, with Block silicon nitride is used as the target material, under the vacuum degree of 1×10 ^-5 Pa, it is bombarded with argon ions and then heat treated at high temperature. The bombardment voltage of argon ions is 10-100KeV, and the density of argon ions is (1-5)× 10 ¹⁶ ions/cm ³ , the heat treatment temperature is 200-450°C, and the heat treatment time is 2-12h.

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