医用316L不锈钢表面改性研究及发展

316L不锈钢因其优良的性能和低廉的价格广泛应用于临床及医疗领域。通过分析医用316L不锈钢目前存在的主要问题及发展状况,对医用316L不锈钢近年来表面改性的新方法和新成果进行了较为详细的介绍,表明表面改性技术是解决临床应用问题的良好途径,为医用316L不锈钢的医学应用提供了新的发展机遇。     

医用316L不锈钢表面改性的研究进展

316L不锈钢作为生物医用材料在近20年内被广泛应用在矫形外科植入物、牙种植体和冠状动脉支架等领域。分析了目前医用316L不锈钢在临床应用中存在的主要问题,指出生物相容性、耐腐蚀性和耐磨损性有待提高和表面改性是改善上述问题的有效途径。综述了医用316L不锈钢表面改性的各种途径及研究成果,并展望了316L不锈钢表面改性的研究趋势。     

掺钽TiO2薄膜的生物活性研究

采用射频磁控溅射技术在表面纳米化316L不锈钢基体上制备掺钽TiO2薄膜,研究了不同掺钽量对表面纳米化316L不锈钢基TiO2薄膜形貌、结构、亲水性和生物活性的影响规律。结果表明掺杂适量的钽能够细化TiO2薄膜颗粒;掺钽能够改善TiO2薄膜的亲水性和生物活性;含钽36%的TiO2薄膜表面自由能比未掺杂时提高了30.1mN/m,在SBF溶液中能促进羟基磷灰石在其表面晶化。     

Microstructure and abrasive behaviors of TiC-316L composites prepared by warm compaction and microwave sintering

316L stainless steel composites with various weight fractions of TiC particles were prepared using warm compaction and microwave sintering. Abrasion resistance measurements were used to study the abrasive behaviors of TiC-316L stainless steel composites. The effects of TiC content and preparation methods on the microstructure and mechanical properties of 316L stainless steel composites have been investigated. The results showed that the sample prepared by warm compaction and microwave sintering exhibited significantly superior densification, higher hardness, and better abrasion resistance when compared with conventionally processed counterpart. TiC particles reinforcement improved the abrasion resistance of 316L stainless steel, and the abrasion resistance of the composites was considerably better than that of the 316L stainless steel. The volume loss initially decreases with increasing TiC content up to 5 wt.%, it then slightly increases as increase the TiC particles content to 10 and 15 wt.%. In this present abrasion tests, the composites using 5 wt.% TiC addition offers a high abrasion resistance.     

Effect of Copper and Bronze Addition on Corrosion Resistance of Alloyed 316L Stainless Steel Cladded on Plain Carbon Steel by Powder Metallurgy

A sandwich structure with cladding alloyed 316L stainless steel on plain carbon steel was prepared by means of powder metallurgy (PM) processing. Electrolytic Cu and prealloyed bronze (95Cu wt pct, 5Sn wt pct) were added in different contents up to 15% into the surface cladded 316L layers and the effect of alloying concentrations on the corrosion resistance of the 316L cladding layers was studied. The corrosion performances of the cladding samples were studied by immersion tests and potentio-dynamic anodic polarization tests in H_2S0_4 and FeCl_3 solutions. Both 316L and alloyed 316L surface layers with 1.0 mm depth produced by PM cladding had an effect to improve corrosion resistance in H2SO4 and FeCI3 solutions. Small Cu and bronze addition (4%) had a positive effect in H_2SO_4 and FeCl3 solutions. 4% Cu alloyed 316L surface layer produced by PM cladding showed similar anodic polarization behaviour to the 316L cladding layer in H_2SO_4 and FeCl_3 solutions.     

316L不锈钢表面纳米化后腐蚀性能研究

对表面纳米化和未经表面纳米化处理的316L不锈钢的样品分别进行点蚀实验和应力腐蚀对比实验,在3.5%(质量分数)NaCl水溶液中分别测出它们的极化曲线.结果表明,316L不锈钢表面纳米化后抗点蚀性能下降,抗应力腐蚀性能提高.对应力腐蚀断口的SEM 分析发现,316L不锈钢应力腐蚀断口有明显分区现象,断裂形式为韧性断裂,开裂通道既有穿晶型也有沿晶型.     

粉末冶金316L不锈钢抗腐蚀性能及其合金元素Si的作用

研究表明,添加4wt%Si 的粉末冶金316L 不锈钢由单相奥氏体转变为奥氏体+铁素体双相组织,烧结密度和体积收缩率分别提高12%和230%,疏松和孔隙明显减少,从而显著提高抗 Cl~-离子腐蚀性能,接近冶炼316L 不锈钢的水平。     

Synthesis of nanostructured zirconia electrodeposited films on AISI 316L stainless steel and its behaviour in corrosion resistance assessment

This work deals with the study of AISI 316L stainless steel samples coated with nanostructured zirconia thin films, using electrodeposition methods. The chemical composition and compounds formed were determined by X-ray photoelectron spectroscopy (XPS). The morphology of zirconia films was analysed by scanning electron microscopy (SEM) and atomic force microscopy (AFM).Corrosion resistance of the coated steel was tested in a chloride environment. XPS analysis results show zirconium element on the metal surface, bound to oxygen-forming zirconia. The anodic polarization curves obtained in Hank's solution show that zirconia coating can be used as protective coating against pitting corrosion of AISI 316L stainless steels.     

Experimental investigation on corrosion and hardness of ion implanted AISI 316L stainless steel

The AISI 316L stainless steel has been widely used both in artificial knee and hip joints in bio-medical applications. In the present study AISI 316L SS was implanted with two different ions: nitrogen and helium at 100 keV with a dose of 1 × 10¹⁷ ions/cm² at room temperature. The crystallographic orientation and surface morphology were studied using X-ray diffraction (XRD) and scanning electron microscope (SEM). The effects of ion implantation on the corrosion performance of AISI 316L stainless steel was evaluated in 0.9% NaCl solution using electro chemical test both on the virgin and implanted samples. The subsequent Tafel analysis shows that the ion implanted specimens were more corrosion resistant when compared to the bare specimens. Microhardness was also measured by Vickers method by varying the loads. The results of the studies indicated that there was a significant improvement in both corrosion resistance and hardness of implanted samples.     

几种超级不锈钢在模拟烟气脱硫环境中的点蚀行为

目前,针对904L,254s Mo和2507等几种主要备选超级不锈钢在烟气脱硫环境中的耐点蚀性能缺乏系统研究。在温度分别为20、40、70℃的死亡绿液溶液中,利用循环伏安曲线和扫描电镜(SEM)法,对316不锈钢和超级不锈钢904L、254s Mo及2507的极化行为和点蚀形貌进行了研究。结果表明:在该环境中,升高温度可降低4种不锈钢表面钝化膜稳定性并提高其点蚀敏感性;在不同温度环境下,316不锈钢均有严重的点蚀现象发生,而254s Mo和2507不锈钢表面均无明显点蚀迹象;在20℃时,904L不锈钢表面无明显点蚀迹象,40℃时,其表面出现典型的点蚀形貌,但点蚀坑尺寸较小,在70℃的高温下,其点蚀坑尺寸明显增大,点蚀损伤严重;254s Mo和2507均适合作烟气脱硫设备材料,而316、904L在该环境中需谨慎使用。     

Friction and wear behaviors of a gradient nano-grained AISI 316L stainless steel under dry and oil-lubricated conditions

A gradient nano-grained (GNG) surface layer was fabricated on an AISI 316L stainless steel (SS) by using the surface mechanical rolling treatment (SMRT). Reciprocating dry and oil-lubricated sliding tests of the GNG 316L SS in air at room temperature were conducted in comparison with the coarse-grained (CG) counterpart. Worn surface morphologies and subsurface microstructures were investigated for both 316L SS samples. 316L SS with a GNG surface layer shows a significantly improved wear resistance, especially under oil-lubricated condition. The notably wear resistance enhancement of the GNG 316L SS is attributed to the GNG surface layer with high strain accommodation ability and high hardness, which can reduce the wear volume in the running-in stage effectively.     

An effective approach to activate 316L stainless steel for biomimetic coating of calcium phosphate: electrochemical pretreatment

In this paper, an electrochemical (EC) method to activate 316L stainless steel (denoted as 316L) surface for biomimetic calcium phosphate (Ca–P) coatings was reported. After EC treatment, a gel-like Ca–P film with a thickness of 150 nm was generated on the stainless steel surface after treatment, which was composed of amorphous phase of calcium phosphate with a large number of crystal nuclei of octacalcium phosphate (OCP) inside. This Ca–P thin film is the main factor that causes Ca–P formation under biomimetic condition. The effectiveness of EC treatment was also compared with alkali heat (AH) pretreatment in producing biomimetic coating on 316L. A uniform Ca–P coating formed on EC treated samples after samples were immersed in saturated calcium solution (SCS) for several hours, while only some island-like deposits were found on the sample surface with AH treatment followed by immersion in SCS for several days. This work has explored a novel and effective pretreatment method to activate 316L implant surface, which can be expected to be applied to activate other metal implants.     

Investigation of dry sliding wear properties of boron doped powder metallurgy 316L stainless steel

This paper describes wear behavior of powder metallurgy (PM) 316L stainless steel with additions of elemental boron with the aim of producing superior mechanical properties. The wear test of the samples is conducted using a pin specimen of PM 316L stainless steel doped with elemental boron and a steel disc specimen with hardness of 180 HV10. Densification achieved with boron addition due to the liquid phase formation up to 95% of theoretical density with 0.6 wt.% boron addition. Most mechanical properties such as hardness, tensile strength and yield strength were improved with boron addition. The wear rate of PM 316L stainless steel decreased from 4.3 × 10⁻⁶ to 0.8 × 10⁻⁶ mm³/Nm with the addition of 0.6 wt.% elemental boron. The abrasive-induced delamination wear dominated at the samples. Scanning electron microscopy observations of the worn surfaces revealed that plastic deformation occurred with delamination of surface layers in the sintered conditions.     

In vitro testing of surface-modified biomaterials

The influence of surface modification treatments such as ion implantation and sputter coating on an in vitro rat bone-marrow cell culture was studied by scanning electron microscopy and X-ray microanalysis. 316 L stainless steel, Ti–6Al–4V and Ti–5Al–2.5Fe were nitrogen ion-implanted with three fluences: 1015, 1016 and 1017 ion cm-2 with an energy beam of 40 keV. Both nitrogen and carbon sputter-coated 316 L stainless steel samples were also studied. Polished 316 L stainless steel, Ti–6Al–4V, Ti–5Al–2.5Fe and ThermanoxTM were also studied, in order to give comparative information. The materials were inoculated with a droplet of cell suspension and were maintained for 3 wk. A mineralized extracellular matrix was formed on all materials except on nitrogen sputter-coated 316 L stainless steel. The morphology of the cell cultures obtained on nitrogen-ion implanted materials was similar to those obtained on the untreated materials and ThermanoxTM. The observation of the interface between the cell layer and the substrata showed the presence of calcium- and phosphorus-rich globular deposits associated with collagen fibres. A higher density of these globular deposits was observed on the ion-implanted materials.     

Microstructural characterization and mechanical integrity of stainless steel 316L clad layers deposited via wire arc additive manufacturing for nuclear applications

The potential applications of stainless steel 316L components using wire arc additive manufacturing offers many benefits such as improved part complexity, higher deposition rate and less material waste. Microstructural examination indicates the strong interlayer bonding between cladded layers and was mainly austenitic with columnar and equiaxed dendrites while equiaxed grains with annealing twins were observed in the stainless steel 316L substrate. In the current study, we report that stainless steel 316L additively cladded via wire arc additive manufacturing exhibits a 11 % and 14 % increase in the yield strength and tensile strength, correspondingly in contrast to the stainless steel 316L substrate. The enhanced mechanical properties are attributed to the columnar structure and interlayer remelted peritectic growth. Hardness values were higher at the cladded layers compared to the interface and substrate. Interface sample failed in the substrate side and all samples exhibited ductile mode of fracture with fine dimples and micro voids. Wire arc additive manufacturing process can be employed for producing or repairing components with better mechanical properties and corrosion performance for elevated temperature environments including nuclear reactor applications.     

Reduction of 3T3 Fibroblast Adhesion on SS316L by Methyl-Terminated SAMs

Inhibiting the non-specific adhesion of cells and proteins to biomaterials such as stents, catheters and guide wires is an important interfacial issue that needs to be addressed in order to reduce surface-related implant complications. Medical grade stainless steel 316L was used as a model system to address this issue. To alter the interfacial property of the implant, self assembled monolayers of long chain phosphonic acids with -CH(3), -COOH, -OH tail groups were formed on the native oxide surface of medical grade stainless steel 316L. The effect of varying the tail groups on 3T3 fibroblast adhesion was investigated. The methyl terminated phosphonic acid significantly prevented cell adhesion however presentation of hydrophilic tail groups at the interface did not significantly reduce cell adhesion when compared to the control stainless steel 316L.     

Corrosion Resistance Studies of Austenitic Stainless Steel Grades in Molten Zinc-Aluminum Alloy Galvanizing Bath

The corrosion inhibition performance and mechanical behavior of galvanized and heat-treated four newly developed austenitic stainless steel grades and type 316L austenitic stainless steel for application as sink rolls in galvanizing baths of 0.14–0.21 wt.% aluminum was investigated and compared through immersion corrosion test to determine the weight loss between 168 and 504 h, tensile test, and Charpy impact test. The delta ferrite content of the test samples was observed and estimated through optical microscopy, feritscope, and ONRL diagram. Scanning electron microscopy and energy dispersive spectroscopy were used to characterize the surface microstructure, morphology, and chemical composition of the galvanized coating of the steel samples. Result showed that only two of the newly developed stainless steel compositions were selected for use in fabrication of galvanizing hardware based on the comparisons of corrosion and mechanical performances of tested alloys.     

脉冲电流处理对轧制316L不锈钢的快速强化

目的 探究不同参数的脉冲电流处理(EPT)对轧制316L不锈钢拉伸性能、显微硬度及微观组织的影响。方法 将轧制的316L不锈钢作为原始样,调节流过样品的脉冲电流密度,分别为130、170、190、260、310 A/mm²,分析脉冲电流密度与其拉伸性能和显微硬度的关系。结果 轧制316L不锈钢的抗拉强度和显微硬度随着脉冲电流密度的增大呈现先增大后减小的趋势,其中当脉冲电流密度为170 A/mm²时达到峰值,抗拉强度由1 485 MPa提升到1 625 MPa,同时显微硬度也由431HV增大到473HV。通过电子背散射衍射分析微观组织可知,与原始样相比,经过脉冲电流处理的样品晶粒尺寸明显减小,马氏体含量明显增多,脉冲电流处理可以促使微观组织快速均匀化。结论 脉冲电流处理可以在短时间内实现轧制316L不锈钢组织的均匀化调控,有效改善轧制316L不锈钢的微观组织,减少轧钢形变织构,促使参与的奥氏体转变为马氏体,使微观组织趋于稳定,同时还可以使轧制316L不锈钢晶粒快速细化,达到细晶强化的效果,有效提高整体抗拉强度和显微硬度。     

Microstructural evaluation of fatigue damage in SA533-B1 and type 316L stainless steels

Transmission electron microscopy (TEM) examinations were made on fatigued SA533-B1 low alloy steel and Type 316L stainless steel specimens with the intention to investigate the mis-orientation changes among dislocation cells and the evolution of dislocation structures. Contrary to what might be expected for the cell structures, no clear relationship between fatigue damage and the mis-orientation changes of cell walls (or subgrain boundaries) was found in the fatigued samples of SA533-B1 steel (a bcc structure); however, significant changes of dislocation structures were observed in the fatigued samples of Type 316L stainless steel (an fcc structure). This could be accounted for by their different structures as well as complicated defect structures such as subgrain boundaries, small carbides, and dislocations inhomogeneously distributed in the SA533-B1 steel. It is interesting to note that at room temperature dislocations of fatigued SS316L specimens were observed to arrange themselves on {111} slip planes, in contrast, at 300°C the dislocations tend to move from their slip planes into subgrain boundaries in the surface layers rather than in the cross sectional layers.     

20/316L双金属管的腐蚀失效原因分析

随着20/316L双金属管在油气生产中的推广应用,关于内衬316L不锈钢的腐蚀失效问题日益突出,尤其是条件苛刻的酸性集输环境下,目前相关研究不多.利用扫描电镜(SEM)、能谱仪(EDS)等测试手段对20/316L双金属管在含H2S-Cl-的酸性集输环境中出现的腐蚀失效问题进行了系统分析,探讨了腐蚀失效的原因.结果表明:20/316L双金属管腐蚀类型为局部腐蚀,主要分布于内衬管316L的底部.腐蚀失效的主要原因是腐蚀介质中存在高浓度的H2S与Cl-,共同促进了钝化膜的破裂与点蚀的发展.当存在较高浓度的H2S与Cl-时,钝化膜薄弱处与电位较低的非金属夹杂物处易发生钝化膜的破裂与金属基体的快速溶解而成为点蚀源,形成点蚀.