Electrochemical studies of stainless steel implanted with nitrogen and oxygen by plasma immersion ion implantation

Plasma Immersion Ion Implantation (PIII) of stainless steel with nitrogen at temperatures lower than 400 °C has been reported to increase the hardness of the material by several times. However, expectations that the corrosion resistance will remain unaffected after implantation were not found to be so. In the present study the influence of post-oxygen implantation on the corrosion resistance of nitrogen implanted stainless steel is presented. Stainless steel samples were subjected to oxygen, nitrogen and post-oxygen ion implantation at different temperatures. GIXRD and microRaman studies of the implanted samples showed that oxygen implantation leads to the formation of an oxide layer consisting of corundum and spinel structures. The corrosion properties of the implanted samples were studied by potentiodynamic polarization and electrochemical impedance techniques in 3.5% NaCl solution. After nitrogen implantation the corrosion current increased and the corrosion potential shifted to the less noble side to − 0.486 V as compared to − 0.284 V for the substrate. Oxygen implantation at 400 °C shifted the corrosion potential to the nobler side to − 0.2 V with decrease of corrosion current. For post-oxygen ion implantation at temperatures lower than 400 °C, the corrosion current was higher than the substrate and the corrosion potential was also on the less noble side. However, post-oxygen ion implantation at 400 °C after nitrogen ion implantation resulted in improved corrosion resistance as the corrosion potential shifted to nobler side and the corrosion current was lower than that of substrate.     

In vitro corrosion behavior of TiN layer produced on orthopedic nickel-titanium shape memory alloy by nitrogen plasma immersion ion implantation using different frequencies

In the present work, the NiTi surface was modified by nitrogen plasma immersion ion implantation (PIII) in an effort to improve the corrosion resistance and mitigate nickel release from the materials. The implanted nitrogen depths and thicknesses of the surface TiN barrier layers were varied by changing the pulsing frequencies during PIII. In order to determine the optimal parameters including the pulsing frequencies, electrochemical tests including open circuit potential (OCP) measurements and potentiodynamic polarization tests were conducted on the untreated and N-implanted NiTi in simulated body fluids (SBF). Our results reveal that the nitride layer produced using a frequency of 50 Hz has the best stability under the OCP conditions and the TiN layer produced using 200 Hz has the highest potentiodynamic stability after immersion in SBF for a long time. The observation can be correlated to the temperature during PIII and the thickness of TiN layer. The TiN layer on the NiTi surface favors deposition of Ca-P composites thereby compensating for the instability of the TiN layer produced at a higher frequency.     

Diamond-like carbon films synthesized on bearing steel surface by plasma immersion ion implantation and deposition

Diamond-like carbon (DLC) films were synthesized by plasma immersion ion implantation and deposition (PIIID) on 9Cr18 bearing steel surface. Influences of working gas pressure and pulse width of the bias voltage on properties of the thin film were investigated. The chemical compositions of the as-deposited films were characterized by Raman spectroscopy. The micro-hardness, friction and wear behavior, corrosion resistance of the samples were evaluated, respectively. Compared with uncoated substrates, micro-hardness results reveal that the maximum is increased by 88.7%. In addition, the friction coefficient decreases to about 0.1, and the corrosion resistance of treated coupons surface are improved significantly.     

Tribological behavior of AISI302 austenitic stainless steel modified by elevated temperature nitrogen plasma immersion ion implantation

AISI302 stainless steel samples were modified by elevated temperature nitrogen plasma immersion ion implantation at temperature ranging from 330 ℃ to 450 ℃. The tribological behaviors of the implanted layers of the samples were investigated. The samples were characterized by Auger electron spectroscopy (AES), glancing angle X-ray diffraction (GXRD), and nanoindentation. The results show that the implantation temperature plays an important rule on the microstructure and surface properties of the implanted layers. The thickness of the modified layer implanted at 390 ℃ is about 9 μm. It is improved about two orders compared with that of the implanted at room temperature. The surface nanohardness and the wear resistance of elevated temperature implanted layers increase significantly, and the friction coefficient decreases obviously in comparison with the unimplanted one. These data suggests that the improvement results from the formation of new phases such as ε-(Fe, Cr, Ni)2 xN, or noncrystal phase.     

Synthesis of indium oxide nanorods on indium phosphide substrate using plasma immersion ion implantation

We report the preparation of indium oxide (In₂O₃) nanorods on indium phosphide (InP) substrate by plasma immersion ion implantation (PIII). The InP substrate was first treated with PIII of acetylene (C₂H₂) ions, then followed by coating the surface with a 40 nm thick gold film. After rapid thermal anneal (RTA) at 750 °C for 15 s, In₂O₃ nanorods were found on InP surface. The In₂O₃ nanorods with diameters of 50-200 nm were examined by Raman spectroscopy, scanning electron microscopy (SEM) and cathodoluminescence (CL). Nanoparticles of gold were found at the tip of the nanorods, suggesting that a vapour-liquid-solid (VLS) mechanism was involved. However, the fact that other species such as nitrogen, argon or oxygen would not lead to the formation of In₂O₃ nanorods also suggests that the carbon liberated from C₂H₂ plays an important role as a catalyst. Carbon has previously been reported to be a reduction agent for the formation of group III sub-oxides. Such sub-oxides provide the vapour source for the growth of nano-materials through further oxidation.     

全方位离子注入与沉积类金刚石碳膜的结构与性能

用等离子体浸没离子注入与沉积(PIIID)复合强化新技术在AISI440C不锈钢表面制备了类金刚石(DLC)碳膜。膜层表面的原子力显微镜(AFM)形貌显示出DLC膜结构致密均匀。Raman光谱分析结果表明,制备的DLC主要是由金刚石键(sp3)和石墨键(sp2)组成的混合无定形碳膜,且sp3键含量大于10%。以纯石墨棒做阴极,C2H2为工作气体条件下合成的DLC薄膜中,sp3键含量总体上较单纯用石墨作阴极而无工作气体条件下合成的DLC薄膜中sp3键含量高。与基体相比,薄膜试样的显微硬度和摩擦磨损性能均得到了较大改善,最大硬度提高88.7%,磨损寿命延长超过4倍。     

Nanoindentation response of PEEK modified by mesh-assisted plasma immersion ion implantation

Polyetheretherketone (PEEK) surfaces have been treated by mesh-assisted plasma immersion ion implantation, significantly altering the viscoelastic properties of the near-surface modified region. The plasticity index derived from nanoindentation load-displacement data indicates that the treated surfaces exhibit greater elastic recovery and reduced plastic deformation compared to unmodified PEEK. Scanning probe microscopy (SPM) images of the surface before and after indentation also show evidence of increased elastic recovery.     

TiN/ZrO2 multilayers synthesized on GCr15 bearing steel using plasma immersion ion implantation and deposition

TiN/ZrO₂ multilayers with different modulation periods were synthesized on GCr15 bearing steel using plasma immersion ion implantation and deposition (PIIID). The total thickness of the TiN/ZrO₂ multilayers was approximately 2 μm and the modulation period was varied from 8 to 400 nm. The as-deposited films were characterized by scanning electron microscopy (SEM), micro-hardness, friction, scratch and corrosion tests. The SEM result indicates that the structure of the TiN/ZrO₂ multilayers has a good periodicity. Micro-hardness testing results show that the hardness enhancement effect takes place at the specific period of 15 nm, 100 nm and 200 nm. In addition, the friction coefficient declined from 0.8 to 0.1-0.3 and the cut-through number was increased greatly. The critical load in the scratch test exceeds 100 N, which shows a high adhesion strength. Moreover, the corrosion resistance of the TiN/ZrO₂ multilayers was improved significantly at the modulation period of 100 nm and 200 nm.     

Effect of pulse rise time on charging effects in plasma immersion ion implantation with dielectric substrates with planar and cylindrical geometries

Using a one-dimensional self-consistent fluid model, the effect of pulse rise time on charging effects at dielectric surfaces is investigated during plasma immersion ion implantation (PIII) with planar and cylindrical geometries. The numerical results demonstrate that the pulse rise time plays an important role in PIII process with dielectric substrates. It is found that the charge dose accumulated on the dielectric surface is significant as decreasing pulse rise time, and the surface potential decreases at the later stage of the pulse, which results in the lower ion impact energy. On the other hand, the longer pulse rise time would lead to the lower charge dose accumulated on the dielectric surface and higher ion impact energy at the later stage of the pulse, which would elevate the effective implanted dose and introduce the ions to the depth deep enough for surface modification.     

The structure and adhesion of hydrogenated amorphous carbon (a-C:H) films synthesized on CoCrMo alloy by plasma immersion ion implantation and deposition at different flow ratios of acetylene to argon

Hydrogenated amorphous carbon (a-C:H) film is deposited on CoCrMo alloy by plasma immersion ion implantation and deposition (PIII-D) at different flow ratios of acetylene to argon (C₂H₂/Ar). The results show that Ar fraction in the C₂H₂-Ar gas mixture has an important effect on the structure and the adhesion of the a-C:H films. When Ar fraction in the C₂H₂-Ar gas mixture is less than 50%, the fabricated a-C:H film composition transfer from graphite-like to diamond-like which contains higher sp³ binding thanks to Ar ion bombardment, and the adhesion strength decreased with the increment of Ar fraction. But when Ar fraction in the C₂H₂-Ar gas mixture is beyond 50%, the fabricated film contains more sp² bonding for thermally driven and exhibits higher adhesion strength with the increment of the Ar fraction.     

钛中间层对改性层结构及性能的影响

用XPS和GXRD研究了铝合金等离子体基离子注入氮后再注入钛最后复合注入氮和钛改性层的成分深度分布及相结构 ,用XTEM观察了改性层截面的组织结构 ,用AFM观察了改性层的表面形貌 ,在此基础上测量了改性层的纳米硬度 ,进行了球盘摩擦磨损试验。结果表明 ,钛中间层使复合改性层的厚度有效增加 ,主要由α Ti,TiN及TiO2 组成 ,且TiN及TiO2 弥散分布在α Ti基材中 ,使表面形貌有所改善 ,使表面硬度及耐磨性明显提高。     

Effect of Sn ion implantation on electrochemical behavior of zircaloy-4

In order to study the effect of tin ion implantation on the aqueous corrosion behavior of zircaloy-4, specimens were implanted by tin ions with a dose range from 1×10¹⁶ to 5×10¹⁷ ions/cm² at an extracted voltage of 40 kV. The valence and element penetration distribution of the surface layer were analyzed by X-ray photoelectron spectroscopy (XPS) and auger electron spectroscopy (AES), respectively. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to examine the micro-morphology and microstructure of tin-implanted samples. When the dose is 5×10¹⁶ ions/cm² or higher, a large number of small tin balls are produced in the implanted surface. The potentiodynamic polarization measurement was employed to evaluate the aqueous corrosion resistance of zircaloy-4 in a 0.5 M H₂SO₄ solution. It was found that a significant improvement was achieved in the aqueous corrosion behavior of zircaloy-4 implanted with tin when the dose is 1×10¹⁶ ions/cm². When the dose is higher than 1×10¹⁶ ions/cm², the corrosion resistance of zircaloy-4 implanted with tin ions decreased compared with that of the as-received zircaloy-4. Finally, the mechanism of the corrosion behavior of the tin-implanted zircaloy-4 is discussed.     

Structure and tribological properties of modified layer on 2024 aluminum alloy by plasma-based ion implantation with nitrogen/titanium/carbon

1　INTRODUCTIONGoodmachinability ,lowdensityandhighspecif icstrengthmakealuminumanditsalloysextensivelybeusedinmanyindustries ,especiallyinaviationandspaceflightindustry .Howeverlowsurfacehardnessandlowwearresistanceoftenlimittheirengineeringapplications .Nitrogenionimplantationintoalu minumanditsalloysoffersthepossibilityofapplica tionswherebothhighwearresistanceandlowdensityarerequired[15] .Moreover ,ourpreviousinvestiga tion[6 ,7] presentedthatwhenaluminumalloywasim plantedwithnitrogen…