A method for manufacturing ultra-fine grain medical high-purity magnesium tube

Abstract

The invention provides a manufacturing method of a medical high-purity magnesium tube of ultra-fine grains. Pure magnesium is taken as a raw material, and continuously processed in a plurality of steps, so as to obtain the medical magnesium tube of the ultra-fine grains, wherein processing by a plurality of steps refers to the processes of extruding a magnesium ingot into a tube blank, carrying out cold drawing and stretching on the tube blank, drawing in large deformation and plastically drawing in small deformation. By adopting the processing method provided by the invention, over 99.99% of high-purity magnesium is continuously processed in a plurality of steps, and the grains are gradually refined until the diameters are 1-2microns and the surface roughness is smaller than or equal to 0.6. The problems of biosecurity, material stability and too fast degradation of an existing magnesium metal tube entering clinic application are solved. The high-purity magnesium metal tube which is ultrafine in grain, relatively high in yield strength and tensile strength, and uniform in corrosion and degradation can be obtained. In addition, no alloy element and a second phase are contained, so that an indissolvable substance is not left after in vivo degradation. Compared with the prior art, the method is significantly improved and enhanced.

Description

technical field [0001] The invention relates to a manufacturing method in the technical field of metal materials, in particular to a manufacturing method for an ultrafine-grained magnesium metal pipe used in the medical device industry. Background technique [0002] Biodegradable absorbing materials in vivo are one of the important directions for the development of biomaterials. As a biomedical material, magnesium has a good basis for medical safety, and magnesium metal materials have become very promising medical implants in the future because of their good comprehensive mechanical properties. Entry material. Studies have shown that the biggest problem with existing magnesium metal implants is the rapid degradation rate after implantation and the biological safety of some magnesium alloys. Therefore, while ensuring the biological safety of its materials, it is an important condition for existing related devices to enter clinical use by greatly improving their own degradati...

AI Technical Summary

Problems solved by technology

[0005] First, the purity of the magnesium alloy mentioned in this patent is above 99.95%, and the impurity content in magnesium of this level of purity, especially Fe, Ni, and Cu, which have a great influence on the degradation performance, is relatively high (the content of Fe is 30ppm ~50ppm, Ni content is about 10ppm, Cu content is about 20ppm), the degradation rate is difficult to control, and unstable factors are prone to appear during the degradation process;

[0006] Second, the alloy contains rare earth and aluminum elements, which are toxic to the human body, and there are certain problems in the long-term biological safety after implantation;

[0007] Third, the material is a magnesium alloy containing a variety of alloying elements, and it is easy to form a stable second-phase intermetallic compound. It is not easy to be decomposed and absorbed in the body, and becomes a potential source of foreign matter, which may increase the risk of inflammatory response

[0008] Fourth, the patent briefly describes the processing process of magnesium alloy pipes, but does not make requirements on the parameters that have a key impact on the degradation performance, such as grain size and surface finish.

[0011] Third, the tube billet described in step five of the patent is obtained by machining on an ingot. In this technical means, the tube billet processing efficiency is low, the concentricity error is large, and the scrap rate is high, so it is difficult to achieve mass production. Requirements and it is difficult to ensure the consistency of pipe wall thickness

[0012] Fourth, the technical solution mentioned in the patent does not describe the requirements for the surface finish of the magnesium tube, but a large number of experiments and researches have shown that due to the effects of the tip discharge on the rough surface and the formation of corrosion galvanic couples due to the potential difference on the surface of different smoothness, the surface The smoothness has a great influence on the degradation of magnesium. The higher the surface finish of the magnesium metal material, the more uniform the degradation, and the uniform degradation can ensure that the implanted device will not suddenly fail during service.

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