1 technical principle: the harmonic influence of structural optimisation and material choice.
The basis of using 3D printing technology with metal to improve medical device corrosion resistance is its special material choice and structural optimisation power.
Titanium alloy (Ti6Al4V), the most commonly used medical metal, naturally forms a strong protective layer of titanium dioxide (TiO₂) on its surface, which stops it from rusting due to human fluids. For dental restorations and orthopaedic implants, its excellent mechanical qualities and biocompatibility make it the chosen material.
In highly frictional situations, cobalt chromium alloy shows outstanding wear resistance and hardness; the oxide coating developed on the surface improves corrosion resistance even more. It is primarily used in fields such as prosthetic joints and cardiovascular stents.
Porous titanium structure: The laser powder bed melting (PBF-LB) method produces porous titanium that modifies implant stiffness and stimulates bone tissue development by means of its complex pore structure, therefore enabling fluid circulation and lowering the local corrosion risk.
Complex pore design: Metal 3D printing simplifies the creation of complex pore structures that conventional methods find challenging. Through optimal stress distribution, these pores not only lighten the equipment's weight but also lower the likelihood of corrosion development.
Functionally graded materials: You can improve corrosion resistance in specific areas of a component while maintaining its overall strength and toughness by changing the material composition gradually within the same part.
2 Clinical Case: Laboratory to Ward Corrosion Revolution
Several clinical situations have confirmed the superiority of using 3D printing technology with metal in terms of corrosion resistance for medical equipment.
By means of porous structural design, German business HearTech produces personalised ear moulds using 3D-printed titanium alloy, therefore greatly enhancing the breathability and corrosion resistance of the equipment. According to patient comments, comfort rises by 60%, and the efficacy of the hearing aids improves by 20%.
The SLM technology aerospace engine turbopump, created together by Northwestern Polytechnical University and China Aerospace Science and Industry Corporation, is made from a special titanium alloy that resists corrosion well in tough conditions.
Made of titanium alloy material, the 3D-printed earphone shell designed for musicians by domestic brand QDC guarantees the endurance of the equipment under high-frequency use and achieves a -35dB sound isolation effect.
Demir et al. used SLM technology to make cobalt chromium alloy cardiovascular stents by optimising process parameters, which improved the stents' density and strength. The oxide film developed on its surface sufficiently prevents blood corrosion and increases the stent's service life.
3 Technical Difficulties and Remarks on Solutions: Moving from Labs to Mass Applications
Although the technology for metal 3D printing has demonstrated great benefits in enhancing the corrosion resistance of medical equipment, its broad application still confronts several difficulties.
Cost issues: High-cost, high-performance materials like titanium alloys restrict their use in throw-away medical equipment. Investigating low-cost materials like medical-grade stainless steel (such as 316L) and lowering material prices by mass production are part of the answer.
Materials that degrade: To achieve regulated degradation rates, the fast breakdown properties of biodegradable materials, including magnesium alloys and zinc alloys in vivo, need additional optimisation via alloying or surface treatment.
Post-processing accuracy and printing precision:
Uniformity of fine structure: The mechanical qualities and corrosion resistance of the equipment depend on the homogeneity of the pore structure-that of 0.5mm pore size. Optimising printing parameters like laser power and scanning speed will help raise printing accuracy.
Post-processing technological innovation: Equipment must be post-processed-that is, polished and ground-after printing to eliminate surface flaws and increase corrosion resistance and biocompatibility.
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