The Study On The Magnesium Diamond-Like Carbon Composites Used For Biomaterials

It is easy for magnesium alloy materials to corrode and decompose in the environment which has chloride and the degradation products are essential elements of the human body. But, the degradation products can be absorbed and discharge by the body which does not cause adverse reaction. As a cardiovascular stent materials which has good mechanical properties and biocompatibility properties. But, the corrosion speed of magnesium is highly in the body fluid environment, which limits the application of magnesium as a biomedical material. DLC film is a performance similar to amorphous carbon diamond film with high hardness, good wear resistance, chemical inertness and biocompatibility. Combined DLC film and magnesium substrate, using the corrosion resistance of DLC film, slow down the corrosion rate of magnesium alloy in body fluids. Taking advantage of its good biological compatibility, improve the compatibility of implant materials in the human body.This project puts forward the new concept of the preparation of medical magnesium matrix composites:first of all, make it meets the mechanical properties when it as the implant material through quenching to improve the plasticity and strength of AZ31B magnesium alloy material. A graded intermediate layer design has been proposed prior to deposition of DLC by combining plasma enhanced unbalanced magnetron sputtering physical vapor deposition and microwave electron cyclotron resonance plasma enhanced chemical vapor deposition techniques. Improvement in low adhesion between DLC films and magnesium substrate can be achieved by depositing the graded intermediate layer of Ti/TixCy、Si/SixNy. Then conduct surface modification of magnesium matrix through microwave plasma composite deposition technology.Titanium as transition elements, when the transition bias was 100V, titanium target current 0.2A and carbon target power 200W, various properties of the film were the best. Raman spectroscopy experiments showed that DLC films successfully deposited on the surface of the substrate. SEM and AFM showed that the DLC film was dense. Mechanical properties of the film (hardness and elastic modulus, adhesion, film thickness) were the best. Static contact angle and electrochemical experiments showed that the film effectively prevent the internal analog body fluid into the membrane, reducing the corrosion rate of magnesium alloy. Silicon transition elements, by changing the bias film deposition, DLC films successfully deposited on the surface of the substrate. When the deposition bias voltage was 100V that the surface morphology and mechanical properties of the film were the best. By comparing the experimental, after depositing the DLC film of magnesium alloy corrosion rate was significantly reduced. Hemolysis experiments showed that the DLC film hemolysis rate <5%, meets the requirements of biomedical materials and has the biocompatible property.