Nickel-free Stainless Steel for Medical Applications

BIOSS4 steel is essentially a nickel-free austenitic stainless steel developed by the Institute of Metal Research, Chinese Academy of Sciences, in response to nickel allergy problems associated with nickel-containing stainless steels that are widely used in medical applications. The high nitrogen content of this steel effectively maintains the austenitic stability and also contributes to the high levels of corrosion resistance and strength. BIOSS4 steel possesses a good combination of high strength and toughness, better corrosion resistance, and better blood compatibility, in comparison with the medical 316L stainless steel. Potential applications of BIOSS4 steel can include medical implantation material and orthodontic or orthopedic devices, as well as jewelries and other decorations.

Strain rate and cold rolling dependence of tensile strength and ductility in high nitrogen nickel-free austenitic stainless steel

The tensile strength and ductility of a high nitrogen nickel-free austenitic stainless steel with solution and cold rolling treatment were investigated by performing tensile tests at different strain rates and at room temperature. The tensile tests demonstrated that this steel exhibits a significant strain rate and cold rolling dependence of the tensile strength and ductility.With the increase of the strain rate from 10^-4s^-1to 1 s^-1, the yield strength and ultimate tensile strength increase and the uniform elongation and total elongation decrease. The analysis of the double logarithmic stress–strain curves showed that this steel exhibits a two-stage strain hardening behavior, which can be well examined and analyzed by using the Ludwigson equation. The strain hardening exponents at low and high strain regions（n2and n1） and the transition strain（εL） decrease with increasing strain rate and the increase of cold rolling RA. Based on the analysis results of the stress–strain curves, the transmission electron microscopy characterization of the microstructure and the scanning electron microscopy observation of the deformation surfaces, the significant strain rate and cold rolling dependence of the strength and ductility of this steel were discussed and connected with the variation in the work hardening and dislocation activity with strain rate and cold rolling.

Effect of Grain Size on Mechanical Properties of Nickel-Free High Nitrogen Austenitic Stainless Steel

The fine grained structures of nickel-free high nitrogen austenitic stainless steels had been obtained by means of cold rolling and subsequent annealing. The relationship between microstructure and mechanical properties and gain size of nickel-free high nitrogen austenitic stainless steels was examined. High strength and good ductility of the steel were found. In the grain size range, the Hall-Petch dependency for yield stress, tensile strength, and hardness was valid for grain size ranges for the nickel-free high nitrogen austenitic stainless steel. In the present study, the ductility of cold rolled nickel-free high nitrogen austenitic stainless steel decreased with annealing time when the grain size was refined. The fracture surfaces of the tensile specimens in the grain size range were covered with dimples as usually seen in a ductile fracture mode.

In vitro Study on a New High Nitrogen Nickel-free Austenitic Stainless Steel for Coronary Stents

Most commercialized coronary stents are made of 316L stainless steels due to its good combination of properties, and currently some new stents are made of cobalt-based alloy owing to its higher mechanical properties. However, the presence of high quantity of nickel and/or cobalt elements in these materials, which are known to trigger the toxic and allergic responses, has caused many concerns. Nickel-free austenitic stainless steels have been developed in order to solve these problems. In this paper, based on the development of a new Fe- Cr-Mn-Mo-N type high nitrogen nickel-free austenitic stainless steel, properties such as mechanical property, corrosion resistance in Hankls solution, and in vitro blood compatibility including the kinetic clotting time and the platelets adhesion, were investigated in comparison to the above two conventional materials, a 316L stainless steel and a Co-28Cr-6Mo alloy. The results showed that the new high nitrogen steel possessed better combination of mechanical properties, corrosion resistance and blood compatibility than those of 316L steel and the Co-28Cr-OMo alloy, and can be a promising alternative material for manufacture of coronary stents.

Nickel-free sealing technology for anodic oxidation film of aluminum alloy at room temperature

Different additives were added into the potassium fluorozirconate solution to prepare different nickelfree sealing reagents,with which the anodic oxidation film of aluminum alloy was sealed at room temperature.The phosphor chromic acid weight loss method was used to evaluate the sealing effects.Using electron scanning microscopy(SEM),the surface and cross-sectional micromorphologies of the anodic oxidation films sealed by different fluorozirconate sealants were observed.The position and state of zirconium element distribution in the film hole were investigated by the further quantitative and distribution analysis of Zr element.This study provides an experimental evidence for the theoretical studies of fluorozirconate-sealed anodic oxidation films.It is shown that the fluorozirconate has good sealing effects and has a wide prospect for sealing the aluminum alloy samples.Its products were highly corrosion resistant,and were filled in the openings of the micropores in the oxide film.

Application of Grain Boundary Engineering to Improve Intergranular Corrosion Resistance in a Fe–Cr–Mn–Mo–N High-Nitrogen and Nickel-Free Austenitic Stainless Steel

Optimization of grain boundary engineering(GBE) process is explored in a Fe–20Cr–19Mn–2Mo–0.82N high-nitrogen and nickel-free austenitic stainless steel, and its intergranular corrosion(IGC) property after GBE treatment is experimentally evaluated. The proportion of low Σ coincidence site lattice(CSL) boundaries reaches 79.4% in the sample processed with 5% cold rolling and annealing at 1423 K for 72 h;there is an increase of 32.1% compared with the solution-treated sample. After grain boundary character distribution optimization, IGC performance is noticeably improved. Only Σ3 boundaries in the special boundaries are resistant to IGC under the experimental condition. The size of grain cluster enlarges with increasing fraction of low ΣCSL boundaries, and the amount of Σ3 boundaries interrupting the random boundary network increases during growth of the clusters, which is the essential reason for the improvement of IGC resistance.

Effect of Cold Deformation on the Friction–Wear Property of a Biomedical Nickel-Free High-Nitrogen Stainless Steel

The microstructural,mechanical and corrosion properties of different cold-rolled biomedical nickel-free highnitrogen stainless steels（NFHNSSs） were investigated to study the effect of cold deformation on its dry wear resistance as well as corrosion–wear behaviors in distilled water and Hank＇s solution. The results indicated that NFHNSS was characterized by stable austenite and possessed excellent work-hardening capacity; due to increasing cold deformation,the corrosion resistance just decreased very slightly and the dry wear rate decreased initially but subsequently increased,while the corrosion–wear resistance was improved monotonically in both distilled water and Hank＇s solution in spite of the presence of corrosive ions. The friction coefficients for different cold-rolled NFHNSSs were very close under the same lubricating condition,but they were the largest in distilled water compared to that in dry wear tests and Hank＇s solution.

High nitrogen nickel-free austenitic stainless steel:A promising coronary stent material

Currently commercialized coronary stents are mainly made of the medical 316L stainless steel and cobalt-based alloy(L605) due to their good combination of properties,especially excellent mechanical properties.However,the presence of high quantity of nickel and/or cobalt elements,the agents known to trigger the toxic and allergic responses,in these materials has caused many clinic concerns.The potential adverse effect of nickel ions release has prompted the development of high nitrogen nickel-free austenitic stainless steels for medical application.Nitrogen in steel is not only to replace the nickel but also improve the properties of steel.In this paper,the harmfulness and release of nickel from metallic stents,and the advantages in mechanical properties and hemocompatibility of high nitrogen nickel-free stainless steels for coronary stents are reviewed.Apart from the highlight of nickel-free,the superiority of high strength and better hemocompatibility of high nitrogen nickel-free stainless steels can guarantee to manufacture thinner strut coronary stents with remarkable anticoagulation ability.High nitrogen nickel-free stainless steels as a promising coronary stents material will attract more and more clinical doctors and stents makers to bring them into clinical application.

无钴富镍正极材料的火焰辅助喷雾热解合成与性能研究

锂离子电池富镍三元正极材料因其成本低、容量高的优势受到广泛关注,受限于钴的高毒性、低储量,富镍正极材料无钴化成为锂离子电池未来的发展趋势。传统液相法制备无钴富镍材料存在步骤繁琐、耗时长、副产物多等问题。火焰辅助喷雾热解(FASP)方法可一步合成正极材料,具有设备简单、耗时短、环境友好等优点。采用FASP方法制备LiNi_(0.8)Mn_(0.2)O_(2)(NM82)无钴富镍正极材料,探究合成条件对NM82结构、形貌和电化学性能的影响。结果表明,FASP可一步合成NM82正极材料,且其在载气流速1.5L/min、锂过量10%、退火温度800℃条件下的锂镍混排水平最低,放电比容量最高,在0.1C倍率下达到180.2mA∙h/g。

无镍型化学镀铜工艺研究

为了追求环保和可持续发展的目标,无镍化学镀铜被广泛视为未来的趋势。这种镀铜方法显著降低了传统工艺所带来的负面环境影响,它不仅消除了对镍盐的依赖,还将废水和废料的产生降至最低。本文的研究集中在开发一种无镍型化学镀铜镀液,通过对镀液的成分和工艺条件进行深入研究,成功实现了一种具有高沉积速率和稳定性良好的无镍型化学镀铜镀液。研究结果表明,这一创新的无镍电镀系统具有广阔的可持续和环保镀铜应用前景。

铝合金阳极氧化膜低温无镍封孔工艺及其封孔性能

为克服传统沸水封孔高能耗和镍盐封孔污染环境的不足,研制了一种无镍低温封孔工艺,其工艺为:锂盐20~30 g/L,氟锆酸盐3.0~5.0 g/L,表面活性剂1.0~2.0 g/L,有机添加剂N 2.0~4.0 mL/L,温度35~55℃,pH 5.0~5.4,封闭时间宜控制在2~3 min/μm。通过酸浸蚀失重试验和电化学试验法对封孔质量和封孔膜的耐蚀性进行评价。结果表明:采用配制的低温无镍封孔剂进行封闭,膜层酸浸蚀失重<30 mg·dm-2,电化学性能明显改善,其封孔效果优于沸水封孔,略差于常温镍盐封孔。

Fe-Mn系无镍低温钢研究进展

随着能源消耗和环境污染问题日益严峻,液化天然气等清洁能源得到广泛关注。低温钢作为这类能源存储和运输的材料,其应用和研发愈显迫切。Ni钢是低温结构钢的主流选择,但近年来,由于Fe-Mn系钢的经济性和性能的优良性,“以锰代镍”新型低温钢成为科研热点,该类钢通常通过添加Mn、Al和Cu等合金元素调控力学性能,并通过工艺调控达到使用标准。重点阐述了外力参数-变形对力学性能的影响、经典强化机制和变形对强韧性机制的影响;综述了裂纹萌生、溶质偏析、相间强度差和能量吸收等低温断裂的理论原理;系统归纳了韧性的评价指标和试验方法。最后,总结了Fe-Mn系低温钢的相关研究成果,对未来的研究进行了展望。

新型高镍无钴正极材料LiNi_(0.94)Mn_(0.04)Al_(0.02)O_(2)的合成研究

采用固相烧结工艺合成了层状高镍无钴正极材料LiNi_(0.94)Mn_(0.04)Al_(0.02)O_(2)(NMA),并研究了不同烧结温度对NMA正极材料的晶体结构、微观形貌和电化学性能的影响。结果表明,当烧结温度过低时,NMA正极材料的结晶度偏低,并在表面形成残锂。烧结温度过高则会导致层状结构变差和电极表面有害副反应增多。在最佳烧结温度750℃下合成的NMA-750材料具有良好的颗粒形貌、最少的锂镍混排和最完整的层状结构,同时具有最佳的电化学性能:首圈放电比容量(3.0~4.5 V,1 C)为199.5 mA·h/g,循环100圈后容量保持率可达79.04%;在5 C下仍具有147.6 mA·h/g的放电比容量,倍率性能优良。

应用于封装凸块的亚硫酸盐无氰电镀金工艺

[目的]在工业可持续发展战略下,环保无氰电镀金技术正逐步替代传统氰化物电镀金技术,并在微电子封装领域中得到推广应用。[方法]针对液晶驱动芯片封装晶圆电镀金凸块工艺制程,开发出一种新型亚硫酸盐无氰电镀金配方和工艺。[结果]自研无氰电镀金药水中添加了有机膦酸添加剂和晶体调整剂,前者能够充分抑制镍金置换,后者有助于形成低应力的等轴晶组织,可避免施镀过程中国产光刻胶挤出变形现象。该自研无氰电镀金工艺应用于晶圆时可获得微观表面平整均匀和无缺陷的金凸块。[结论]该自研无氰电镀金工艺能够满足晶圆级封装的要求,具备很好的推广应用潜力。

游离粒子摩擦辅助电铸工艺优化与仿真分析

针对游离粒子摩擦辅助电铸工艺存在的垂直空间上摩擦力分布均匀性较差的问题,提出游离粒子垂直向下加压的改进方法。以阴极旋转式镍电铸为例,利用理论推导出压力与摩擦力分布均匀性方程。采用离散元软件Rocky DEM建立压力板游离粒子颗粒模型,并对电铸过程进行仿真。结果表明,对游离粒子加压后,游离粒子与阴极表面的摩擦力在垂直空间上呈上升趋势,两端压力趋于平均,仿真结果与理论模型预测一致。

6063铝合金阳极氧化膜中温无镍封孔工艺

以醋酸镁和醋酸锂为主盐,聚乙二醇600(PEG600)为表面活性剂,对6063铝合金阳极氧化膜进行封孔处理。研究了封孔时的pH、温度和时间对阳极氧化膜耐蚀性的影响,得到较优的封孔工艺参数为:Mg(CH_(3)COO)_(2)·4H_(2)O 3g/L,CH_(3)COOLi 7 g/L,三乙醇胺2 g/L,PEG 6006 g/L,苯并三氮唑(BTA)5 g/L,温度75℃,pH 6.1,时间30 min。采用扫描电子显微镜(SEM)、X射线光电子能谱(XPS)、电化学测试等手段分析了阳极氧化膜封孔前后的微观形貌、元素组成和耐蚀性,并简要分析了封孔机理。在较优工艺条件下封孔后阳极氧化膜的微观表面更加粗糙,耐蚀性良好,封孔产物主要由Mg、Li和Al的氧化物与氢氧化物所组成。

铈掺杂无钴高镍正极材料LiNi_(0.6)Mn_(0.4)O_(2)的制备及性能

为获得无钴高镍正极材料LiNi_(0.6)Mn_(0.4)O_(2)(NM64)的最佳合成方法,采用水热法和共沉淀法对其进行制备,确定共沉淀法为NM64材料的较佳制备方法。为进一步提高共沉淀法制备的NM64材料(下称“NM64-C”)的倍率性能和循环性能,采用Ce离子掺杂对NM64-C进行了优化。结果表明:摩尔比为0.02的Ce离子(0.02Ce)掺杂的NM64-C材料在0.3 C下100次循环后的容量保留率为79.5%,明显优于基材NM64-C(63.9%)。0.02Ce掺杂的NM64-C材料展现出了良好的电化学性能。

无钯化学镀制备导电Ni@Kevlar®复合织物及其电磁屏蔽性能

采用高性能Kevlar®织物作为基体,使用无刻蚀、无钯、无锡的“溶胀-银”方法进行活化,通过化学镀工艺制备Ni@Kevlar®织物。利用扫描电子显微镜(SEM)和高分辨率透射电子显微镜(HRTEM)观察织物表面及纤维截面的微观形貌,探究不同时间下样品的质量增加率、增厚及面密度,并利用X射线光电子能谱仪(XPS)和广角X射线衍射仪(WXRD)测量表面成分及晶体结构,采用四探针测试仪和综合物理性能测量系统(PPMS)测量电、磁性能。结果表明,无刻蚀、无钯、无锡的“溶胀-银”活化处理能在织物表面产生大量的银催化靶点,经化学镀后可得到具有良好导电性和铁磁性的纯镍镀层。同轴法屏蔽效能测试结果表明,Ni@Kevlar®织物在低频波段(0.1 MHz~1.5 GHz)的屏蔽值最高达70 dB,能屏蔽99.99999%的电磁波,高频波段(2~18 GHz)达到25 dB,可满足生活生产的屏蔽需求。

锂离子电池无钴富镍层状正极材料的研究现状及前景

目前钴元素在锂离子电池正极材料中被广泛应用,其对材料循环性能和结构稳定性的提升表现优异。然而因为钴价格高昂、供应链存在风险以及开采受限等因素,降低正极材料中钴的含量甚至实现无钴化是当前的主要研究方向。无钴富镍层状材料成本低、能量密度高,具有一定优势。本文综述了无钴富镍层状正极材料的合成方法和改善性能的手段,有助于研究人员了解该材料的研究进展。

金属注射成形制备高氮无镍奥氏体不锈钢的烧结优化

用粉末冶金方法制备高氮无镍奥氏体不锈钢,可以解决镍过敏问题,节约成本,已成为当今的研究热点。文章采用金属注射成型技术(Metal Injection Molding,MIM)制备此类不锈钢。采用正交试验方法系统研究了烧结温度、氮气压力和保温时间烧结参数对奥氏体不锈钢密度、收缩率和氮含量的影响,以获得最佳烧结参数。研究发现,当烧结温度为1200℃,保温时间为6 h,氮气压力为1100 mbar时,样品具有较高的密度(7.52 g/cm3)和氮含量(0.76%)。渗氮烧结后不锈钢基体为奥氏体。