The pinnacle combination of materials science and surface engineering, forging an unyielding surgical framework that never gives in.

Announcement of the Results

We have successfully integrated cutting-edge materials science with surface treatment technology, launching the "Diamond Bone" series of medical high-tension stainless steel slotted rigid tubes. This product is made of special metallurgical grade 304V/316L stainless steel and adopts the patented "deformation - phase transformation" synergistic strengthening process, which increases the material's yield strength to over 1300 MPa while maintaining an elongation rate of 15%. Combined with nano-level composite surface treatment, the friction coefficient is reduced by 60%, and the biocompatibility reaches the highest rating. It provides an ultimate material solution for implant-grade devices that need to operate in harsh mechanical and chemical environments for a long time.

Research and Development Background Challenges

The rigid inner tubes of high-end medical devices have long been constrained by the "ceiling effect" of material properties. Conventional medical stainless steel (such as 316L) provides excellent biocompatibility and corrosion resistance, but its strength (typically the yield strength is about 690 MPa) is insufficient to meet the extreme requirements for injection force and bending resistance imposed by the increasingly sophisticated heavy and miniaturized devices. Simply increasing the wall thickness will result in a cumbersome device and a narrow inner cavity, and still cannot solve the risk of brittle failure under stress concentration. Moreover, rough or improperly treated surfaces are not only the origin of fatigue cracks, but their high friction coefficient also hinders the smooth passage of the device through tissues and may cause unnecessary tissue damage or thrombosis risks. Materials have become the core bottleneck restricting the performance breakthrough of rigid inner tubes.

Core Technological Innovation

• Microalloying and controlled rolling and cooling (TMCP) process: Jointly developed with top steel enterprises, on the basis of 316L stainless steel, precisely add trace amounts of vanadium (V), niobium (Nb), etc. as carbide-forming elements. Through the innovative "deformation-induced phase transformation" and controlled rolling and cooling technology, a composite structure with ultrafine-grained austenite matrix and nano-scale carbon nitride dispersed distribution is obtained within the material. This structure will refine the grain size of the material to below 2 micrometers, and the size of the nano precipitated phase is less than 50 nanometers. Through the synergistic effect of fine grain strengthening and precipitation strengthening, the material strength is pushed to the limit without damaging toughness and corrosion resistance.
• Deep cold treatment and multi-stage aging process: After precise slotting, introduce a -196℃ deep cold treatment stage to promote the transformation of residual austenite to martensite, further strengthening the matrix, and releasing processing stress. Then, perform multi-stage precise aging treatment by regulating the composition, size and distribution of precipitated phases, achieving "fine-tuning" of material strength, elastic modulus and fatigue limit. This process enables the pipe to achieve ultra-high static strength while increasing its fatigue life under cyclic loading by 200%.
• Multi-layer gradient functional coating technology: Develop a "passivation-doping-ultralow friction" three-level surface treatment system. First, perform electrochemical passivation to form a stable, dense and chromium-rich oxide layer, laying the foundation for corrosion resistance; then, use plasma immersion ion implantation technology to gradient-distribute nitrogen and carbon elements into the tens of nanometers depth of the surface layer, forming a diamond-like amorphous structure, increasing the surface hardness to above HV 1200; finally, graft super-hydrophilic/super-lubricating polymer brushes, forming a stable hydrated lubricating layer in the body fluid environment, reducing the dry friction coefficient to below 0.05 and the wet friction coefficient to below 0.01.

Mechanism of Action

The outstanding performance of this product stems from the comprehensive material innovation from the bulk phase to the surface layer. At the bulk phase level, ultrafine crystals and nano precipitated phases have formed a strong and uniform microstructure framework, significantly hindering dislocation movement, enabling the material to maintain elastic deformation when subjected to extremely high loads, and delaying the occurrence of plastic yield and fracture. At the mesoscopic level, the microstructure after special heat treatment has a lower Bauschinger effect, meaning that its strength attenuation is smaller when subjected to repeated tension and compression loads, and its fatigue resistance is excellent. At the surface interface level, the gradient functional coating has constructed a "flexible and rigid" protective system: the inner layer of the hardened layer resists scratches and wear, the middle layer of the bonding layer ensures the adhesion of the coating, and the external layer of the ultra-lubricating layer minimizes the mechanical interlocking and adhesion with biological tissues, achieving the ideal state of "strong but not sticky," which protects both the instrument and the tissue.

Efficacy Verification

The results of the material testing are remarkable: In the tensile test, the yield strength remained stable within the range of 1300-1400 MPa, the tensile strength exceeded 1500 MPa, the uniform elongation rate was better than 15%, and the strength-to-plasticity product (the product of strength and plasticity) reached the top level of the industry. The rotational bending fatigue test showed that its fatigue limit after 10^7 cycles was as high as 550 MPa, which was 2.5 times that of conventional materials. The electrochemical polarization test in simulated body fluid (PBS, 37°C) indicated that its pitting potential exceeded 1000 mV, the corrosion current density was as low as 10^-8 A/cm², and the corrosion resistance was excellent. The animal implantation experiment (6 months) showed that the inflammatory response of the surrounding tissues was mild, the fibrous capsule was thin and uniform, and there were no signs of any corrosion product release. In the clinical prototype testing, the lower tube made of this material performed well in the bone drill guide, and no wear debris was produced even at the highest rotational speed and feed pressure, and the resistance to withdraw from the bone was reduced by 70%.

Research and Development Strategy and Philosophy

We firmly believe that "materials are the genes of devices." Our research and development strategy is "full-chain material innovation from atoms to devices." We are not satisfied with merely processing standard material grades; instead, we deeply participate in the entire process of material design, smelting, processing, and treatment. We collaborate with top research institutions in metallurgy, surface physical chemistry, and tribology to understand and control the behavior of materials at the micro-nano scale. Our philosophy is: for each specific clinical challenge, customize the most suitable "material genes." This requires us not only to be proficient in manufacturing processes but also to become practitioners and innovators in material science, ensuring that our products are prepared for ultimate performance at the molecular level.

Future Outlook

Looking to the future, we are moving from "high-performance materials" to "intelligent active materials." We are committed to developing composite materials with self-sensing capabilities, such as embedding distributed optical fiber sensors in the metal matrix, making the pipe itself an intelligent carrier for sensing stress and temperature. At the same time, we are developing bioactive surfaces by loading antibacterial ions (such as silver, zinc) or promoting bone formation factors (such as BMP-2), so that the rigid inner pipe can actively participate in anti-infection or tissue healing processes while fulfilling its mechanical support mission. More prospectively, we are researching "4D printing" intelligent structures based on shape memory alloys or electrostrictive materials, aiming to create the next generation of intelligent surgical shafts that can autonomously adjust local stiffness or shape during key surgical steps according to preset programs or external stimuli (such as body temperature, electric field).