稀土铈对AZ91镁合金表面腐蚀性能的影响

为解决镁合金表面处理工艺复杂、成本高且存在环境污染问题 ,采用气相扩渗法研究了稀土铈对AZ91镁合金表面的渗入及其耐腐蚀性能的影响 .结果表明 ,经过扩渗稀土铈表面处理的AZ91镁合金 ,腐蚀电阻增大近一倍 ,均匀腐蚀速率由 1.85 0mg/m2 ·s降为 0 .876mg/m2 ·s;腐蚀电位正移 ,同一电位下所对应的腐蚀电流密度明显降低 .利用X射线光电子能谱 (XPS)分析了经过扩渗稀土后AZ91镁合金表面的成分中 ,稀土铈是以化合态的形式存在于表层 ,渗入的稀土元素铈起到净化合金表面。

改善铸造铝合金表面耐腐蚀性能的技术

简述了研究铸造铝合金表面耐腐蚀性的必要性。对微弧氧化技术、电沉积、多弧离子镀、化学复合镀和化学转化膜等技术,应用于改善铸造铝合金表面耐腐蚀性进行了综述。提出了对现有的改性技术综合研究和应用的必要性。

浅析浸渍纸层压木质地板表面的几个质量特性

分析影响浸渍纸层压木质地板表面耐污染腐蚀性能、表面胶合性能、表层固化等级和表面清晰度的因素,以利于生产企业有针对性地改进和提高产品质量。

Biocorrosion property and cytocompatibility of calcium phosphate coated Mg alloy

Calcium phosphate coated Mg alloy was prepared. The phase constitute and surface morphology were identified and observed by X-ray diffractometer （XRD） and SEM. The results show that the coating is composed of flake-like CaHPO4-2H2O crystals. The corrosion resistance of the coated Mg alloy was measured by electrochemical polarization and immersion test in comparison with uncoated Mg alloy. Cytocompatibility was designed by observing the attachment, growth and proliferation of L929 cell on both coated and uncoated Mg alloy samples. The results display that the corrosion resistance of the coated Mg alloy is better than that of uncoated one. The immersion test also shows that the calcium phosphate coating can mitigate the corrosion of Mg alloy substrate, and tends to transform into hydroxyapatite （HA）. Compared with uncoated Mg alloy, L929 cells exhibit good adherence, growth and proliferation characteristics on the coated Mg alloy, indicating that the cytocompatibility is significantly improved with the calcium phosphate coating.

Effects of surface nanocrystallization on corrosion resistance of β-type titanium alloy

Surface mechanical attrition treatment (SMAT) was performed on biomedicalβ-type TiNbZrFe alloy for 60 min at room temperature to study the effect of surface nanocrystallization on the corrosion resistance of TiNbZrFe alloy in physiological environment. The surface nanostructure was characterized by TEM, and the electrochemical behaviors of the samples with nanocrystalline layer and coarse grain were comparatively investigated in 0.9% NaCl and 0.2% NaF solutions, respectively. The results indicate that nanocrystallines with the size of 10-30 nm are formed within the surface layer of 30 μm in depth. The nanocrystallized surface behaves higher impedance, more positive corrosion potential and lower corrosion current density in 0.9%NaCl and 0.2%NaF solutions as compared with the coarse grain surface. The improvement of the corrosion resistance is attributed to the rapid formation of stable and dense passive film on the nanocrystallized surface of TiNbZrFe alloy.

Surface modification with SiO_2 coating on biomedical TiNi shape memory alloy by sol-gel method

The effect of heat treatment on the transformation temperature of Ti?52.2%Ni (mole fraction) alloy was studied using differential scanning calorimetry (DSC). The transformation temperatures of the alloy can be adjusted effectively by heat treatment. Dense and stable SiO2 coatings were deposited on the surface of the pre-oxidized TiNi alloy by sol?gel method. The bonding strength of films and matrix was (65.9±1.5) N. The electrochemical corrosion test shows that the TiNi alloy with SiO2 coating has excellent corrosion resistance in the Hank’s simulated body fluid. The release behaviors of Ni ion of the alloy with and without SiO2 coating implanted in the acoustic vesicle of guinea pig were studied by EDS testing, which was inhibited effectively by the dense and stable SiO2 coating on the alloy.

渗锌技术

钢铁制件经过渗锌加工处理后，其表面腐蚀性能和耐磨性能大幅度提高，天津宇晨渗锌科技服务中心现有渗锌加工技术转让，转让条件：属于非专利技术使用权转让，提供专用设备和加工工艺资料，实施技术服务。

Microstructure and properties of Al-coating on AZ31 magnesium alloy prepared by pack-cementation

Al-containing coatings were prepared on AZ31 magnesium alloy by pack-cementation technology.X-ray diffraction(XRD),backscattered electron imaging(BSEI)and energy dispersive spectroscopy(EDS)were jointly employed to characterize the phases,microstructure and composition of the coated samples.The results show that the feedstock composition has a significant impact on the phases,microstructure and thickness of the coatings.For the sample with AlCl3 powder as the activator,the coating is very thick and composed of gradient phases and structures from surface to inside,including small amount ofb-Mg2Al3,coarse eutectic-like structure ofγ-Mg17Al12+δ-Mg,and fineγ-Mg17Al12 precipitations.In contrast,for the sample with AlCl3 and pure Al composite powders as the activator,the coating is relatively thin and contains a thin Al2O3 layer and a small amount of fineγ-Mg17Al12 precipitates.For the pack-cementation aluminizing that is not protected by high-vacuum or inert gas,the addition of pure Al powders can easily introduce the Al2O3 layer into the coating to prevent active Al ions further penetrating into the magnesium matrix,resulting in the thin Al-containing coating.The microhardness and corrosion behavior of the two kinds of aluminized coatings were also studied and discussed.

Improvement of surface corrosion resistance for magnesium alloy by combining thermal spray and cast-infiltration

The present work focuses on a new method combining cast-infiltration with thermal spraying technology to improve the surface corrosion resistance of magnesium alloy.A zinc-based alloy layer was fabricated on the surface of AZ91D magnesium alloy. The microstructure of the layer was characterized by scanning electron microscopy equipped with an energy dispersive X-ray spectroscopy(EDS).The phase constituent of these alloys was identified by X-ray diffractometry(XRD).The analysis results reveal that a zinc-based alloy layer with a thickness of 700μm can form on the surface of AZ91 alloy matrix.The layer is composed of Mg7Zn3,MgZn and a small amount of α-Mg solid solution.The results indicate that the corrosion-resistance of the specimen with a zinc-based alloy layer is much better than that of the specimen without the layer after being immersed in 5%NaCl solution for 240 h, and the layer is more protective for the AZ91 alloy.

Effect of fluoride treatment on corrosion behavior of Mg-Ca binary alloy for implant application

The influence of hydrofluoric acid（HF） treatment on the corrosion behavior of the Mg-0.5Ca alloys was investigated by immersion specimen in sodium hydroxide and HF solutions with various concentrations and durations at room temperature.Microstructural evolutions of the specimens were characterized by atomic force microscopy,X-ray diffraction,field-emission scanning electron microscopy.The corrosion resistance was examined through potentiodynamic polarization and immersion test in Kokubo solution.The results revealed that the fluoride treated Mg-0.5Ca alloys produced by immersion in 40% HF provided more uniform,dense and thicker coating layer（12.6 μm） compared with the 35% HF treated specimen.The electrochemical test showed that the corrosion resistance of fluoride treated specimen was 35 times higher compared with the untreated Mg-0.5Ca alloy specimen in Kokubo solution.In vitro degradation rate of the fluoride treated specimens was much lower than untreated Mg-0.5Ca alloy in Kokubo solution.After immersion test the surface of 40% HF treated sample showed a few corrosion dots,while untreated specimens were fully covered by corrosion products and delamination.Fluoride treated Mg-0.5Ca alloy with 40% HF is a promising candidate as biodegradable implants due to its low degradation kinetics and good biocompatibility.

Microstructure, mechanical and corrosion properties of magnesium alloy bone plate treated by high-energy shot peening

To enhance the mechanical properties and corrosion resistance of magnesium alloys,high-energy shot peening(HESP)was used.According to the results,the in-situ surface nanocrystallization(ISNC)microstructure was fabricated on the magnesium alloy surface,and its formation mechanism was the coordination among twins,dislocations,subgrain boundary formation and dynamic recrystallization.Under the released surface stress of sample,the residual compressive stress and microhardness rose,thus enhancing compactness of the surface passivation film Mg(OH)2.Besides,the corrosion rate dropped by 29.2% in maximum.In the polarization curve,the maximum positive shift of the corrosion potential of sample was 203 mV, and the corrosion current density decreased by 31.25% in maximum.Moreover,the compression resistance and bending resistance of the bone plate were enhanced,and the maximum improvement rates were 18.2% and 23.1%,respectively.Accordingly,HESP significantly enhanced mechanical properties and corrosion resistance of magnesium alloys.

Comparison on corrosion resistance and surface film of pure Mg and Mg−14Li alloy

To study different corrosion resistances and surface film types of hexagonal close-packed(HCP)pure Mg and body-centered cubic(BCC)Mg−14wt.%Li alloy in 0.1 mol/L NaCl,a series of experiments were conducted,including hydrogen evolution,mass loss,in-situ electrochemical testing combined with Raman spectroscopy and microstructural observation.The results indicate that the corrosion resistance of pure Mg is superior to that of Mg−14Li,and the protective function of the surface films on both magnesium systems is elevated within 16 h of immersion in 0.1 mol/L NaCl.An articulated,thick,and needle-like surface film containing Li2CO3 on Mg−14Li,different from the typically thin,flaky Mg(OH)2 film on pure Mg,is confirmed via scanning electron microscopy(SEM).However,both surface films can be broken down at a high anodic over-potential.Thus,different corrosion resistances of the two Mg systems are ascribed to various protective films forming on their surfaces.

Effect of laser surface melting on surface integrity of Al-4.5Cu composites reinforced with SiC and MoS2

Two types of composites were prepared with Al-4.5Cu alloy as a matrix using stir casting method.One was reinforced with 10wt.%of Si C and 2wt.%of MoS2.The other was reinforced with 10wt.%of Si C and 4wt.%of MoS2.Their surfaces were remelted using a CO2 laser beam with an objective to study the influence of laser surface melting(LSM).The topography,microhardness,corrosion resistance and wear resistance of the laser melted surfaces were studied.Overall surface integrity after LSM was compared with as-cast surface.LSM enhanced the microhardness and wear resistance of the surface in each case.Porosity of the laser melted surface was low and corrosion resistance was high.Thus,LSM can be conveniently applied to enhancing the surface integrity of the aluminium composites.However,there is an optimum laser specific energy,around 38 J/m^2 in this study,for obtaining the best surface integrity.

Ultrasonic testing and microscopic analysis on concrete under sulfate attack and cyclic environment

The damage process of concrete exposed to sodium sulfate attack and drying-wetting cycles was investigated. The water to binder(W/B) ratio and the concentration of sulfate solution were taken as variable parameters. Through the experiment, visual change, relative dynamic modulus of elasticity(RDME) and the surface damage layer thickness of concrete were measured.Furthermore, SEM and thermal analysis were used to investigate the changing of microstructure and corrosion products of concrete.The test results show that the ultrasonic velocity is related to the damage layer of concrete. It approves that an increase in damage layer thickness reduces the compactness and the ultrasonic velocity. The deterioration degree of concrete could be estimated effectively by measuring the surface damage layer and the RDME of concrete. It is also found that the content of gypsum in concrete is less than that of ettringite in test, and some gypsum is checked only after a certain corrosion extent. When the concrete is with high W/B ratio or exposed to high concentration of sulfate solution, the content of ettringite first increases and then decreases with corrosion time. However, the content of gypsum increases at a steady rate. The content of corrosion products does not correspond well with the observations of RDME change, and extensive amount of corrosion products can be formed before obvious damage occurs.

Effects of electrolytic concentration on properties of micro-arc film on Ti6Al4V alloy

To study the effect of electrolytic concentration,bioactive ceramic films containing Ca and P on the surface of the Ti6Al4V alloy were prepared by micro-arc oxidation(MAO) in aqueous solutions of different concentrations.Composition,micro-morphology,wettability of the films and their corrosion behavior in a Hank's SBF were studied.Our experimental results show that the film is mainly composed of anatase,rutile and amorphous phases.With an increase in electrolytic concentration,the ratio of rutile in films enlarge and small amounts of calcium phosphate(Ca3(PO4)2) and hydroxyapatite(HA) appear.The number of micropores in films increases but their dimensions decrease and their porosities increase slightly.As the surface roughness of MAO film increases with concentration,the wettablility of the oxide film improves continually,while micro-hardness increases at first and then decreases.MAO treatment clearly improves the corrosion resistance of substrates in a Hank's SBF.

Effect of liquid nitriding at 400–670 ℃ on microstructure and properties of C110 Steel

Liquid nitriding of Cll0 steel was conducted in a wide range of temperatures （400-670 ℃） using a kind of chemical heat-treatments, and the hardness, mechanical and corrosion properties of the nitrided surface were evaluated. Experimental results revealed that the microstructure and phase constituents of the nitrided surface alloy are highly depended on the processing condition. When C 110 steel was subjected to liquid nitriding at 430 ℃, the nitrided layer was almost composed of a thin e-Fe2-3N layer. When C 110 steel was subjected to liquid nitriding at 640 ℃, the phase composition of the nitrided layer was greatly changed. The nitrided layer depth increased significantly with increasing the treating temperature. The liquid nitriding effectively improved the surface hardness. After liquid nitriding, the absorption energy of the treated sample decreased and the tensile strength increased by Charpy V-notch （CVN） test. But the elongation of treated sample decreased. The reason is that the nitrided layer of sample is hardened and there is brittlement by diffusion of nitrogen atom. Despite of treatment temperature, the liquid nitriding can improve the corrosion. After being nitrided at 430 ℃, the nitrided layer of the C110 steel was mainly composed by e-Fe2 3N, which has excellent corrosion resistance and high microhardness, the nitrided sample has the best corrosion resistance. After nitriding temperature over 580 ℃, especially at 680 ℃, the sample＇s surface was covered by the thick oxide layer, which has very low hardness and corrosion resistance. So, the corrosion resistance of samples is severely compromised.

Study the Effect of Boron and Titanium to Resist Corrosion in the Salt Solution for the Alloy （Al-Cu-Mg）

The alloy （AI-Cu-Mg） alloy important one dating back to the series （2xxx） where copper foundries basic element which represents the number （2）, the study relied on foundries add elements boron （B） and titanium （Ti） and then use a heat treatment （homogenizing process） to improve the corrosion resistance in saline （NaC1 3.5%） of the base alloy （A1-Cu-Mg）, was prepared four types of alloys （A, B, C, D） depending on the chemical composition. The results showed that the corrosion resistance in saline solution was the best resistance in the alloy （D） （A1-2% Cu-2% Mg-0.1% B-1.0% Ti） compared with the rest of bullion when an examination of corrosion of the alloy prepared after homogenizing. But by examining the surface roughness of the alloy ingot turned out that （D） is softer than the rest of the surface alloys and this is due to the addition of boron and titanium together increases surface smoothness in alloys because it works to reduce the grain size.

Corrosion resistance and cytocompatibility of Ti-20Zr-10Nb-4Ta alloy surface modified by a focused fiber laser

The corrosion resistance and cytocompatibility of Ti-20 Zr-10 Nb-4 Ta（TZNT） alloy modified by surface laser treatment were investigated. The scanning electron microscopy（SEM） measurements indicated that laser treatment on TZNT alloy generated groove morphologies with the width of^40 μm and the depth of ~10 μm on the surface. The water contact angles along the groove direction decreased by 51%compared with that of the untreated alloy. The laser treatment promoted the oxidation of metallic Ti, Zr and Nb and produced more stable oxides on surface. The corrosion potential increased by 50% and corrosion current density decreased by72% compared with that of the untreated alloy in the anodic polarization test for the alloy in Hank’s solution at 37°C. This indicated the improvement of the corrosion resistance by laser treatment. The cytotoxicity testing results showed that the laser-treated TZNT alloy performed similar MC3 T3-E1 cell viability compared with the untreated alloy. The cells displayed oriented growth along the groove direction due to the increased hydrophilicity. This novel material may be a new candidate in orthopedics and dentistry implantations fields.

Advances in Medical Magnesium Alloy Surface Modification for Corrosion Resistance Improvement

Since the magnesium and magnesium alloys have good load transmission,exceptional biosafety,unique biodegradability,etc,they have significant application possibilities in the field of medical implantation.Furthermore,excellent corrosion resistance is one of the paramount prerequisites for magnesium and magnesium alloys as medical implants.However,magnesium alloys exhibit poor corrosion resistance,leading to rapid degradation in physiological environments due to high corrosion rates.This premature degradation,before completing their intended service life,compromises their structural integrity,severely limiting their clinical applications.Surface modification treatment of magnesium alloy to improve corrosion resistance has become a research hotspot of medical magnesium alloy.This study primarily focused on the research advancements in the corrosion resistance enhancement of medical magnesium alloys.The developmental trajectory and characteristics of medical magnesium alloys were outlined.Additionally,surface modification techniques such as micro-arc oxidation and ion implantation,as well as microstructure and properties of magnesium alloy surfaces after surface modification were reviewed.The formation mechanisms of various coatings were discussed,and their structures and properties were analyzed.The impact of coatings on the degradation rate of magnesium alloys was elucidated,aiming to identify key issues and potential solutions in the implementation and application of surface modification for medical magnesium alloys.Recommendations were also provided,presenting the research directions for surface modification of medical magnesium alloys.