改性纳米SiC粉体对铸造304不锈钢腐蚀性能的研究

在生产条件下采用冲入法制备了改性纳米SiC粉体强化铸造304不锈钢.利用静态浸泡试验、电化学分析法研究了改性纳米SiC粉体对304不锈钢点腐蚀和晶间腐蚀性能的影响.结果表明:经改性纳米SiC粉体强化处理后的304不锈钢耐腐蚀性得到有效提高;添加纳米SiC粉体的304不锈钢在强酸条件下表现出优越的抗晶间腐蚀性能;添加纳米SiC粉体的304不锈钢的电极-电位提高了68 mV、自腐蚀电流减小0.122 mA、腐蚀速率降低了90.12％.     

喷丸处理对304不锈钢焊接接头氯化钠应力腐蚀开裂的影响

对304不锈钢氩弧焊焊接接头表面作了喷丸处理,并在金相显微镜与扫描电镜下对处理后材料表面的微观组织进行了观察,用X射线应力衍射仪测试了喷丸处理后试样的残余应力分布,并进行了NaC1水溶液应力腐蚀试验.结果表明,304不锈钢焊缝在NaCl溶液中具有明显的应力腐蚀开裂敏感性,喷丸处理能够很好地提高焊接构件抗应力腐蚀开裂能力;应力腐蚀裂纹断口表现为脆性断裂,各区的应力腐蚀裂纹属于穿晶型裂纹.     

表面纳米化对β型钛合金耐腐蚀性能的影响(英文)

采用表面机械研磨处理(SMAT)方法对医用β型TiNbZrFe合金表面处理60 min,研究表面纳米化对TiNbZrFe合金在生理环境下耐腐蚀性能的影响。采用TEM观察表层纳米晶微观结构特征,采用电化学方法研究表面为粗晶与纳米晶的TiNbZrFe合金在0.9%NaCl和0.2%NaF溶液环境下的电化学行为。结果表明:TiNbZrFe合金表面形成深度约30μm的纳米晶层,纳米晶尺寸为10~30 nm。在0.9%NaCl和0.2%NaF腐蚀环境下,与粗晶表面相比,表面为纳米晶的合金表现出较高的电阻、较正的自腐蚀电位以及较低的自腐蚀电流密度。合金耐腐蚀性能的提高主要归因于在纳米化的TiNbZrFe合金表面能够快速形成致密且稳定的钝化膜。     

电沉积Fe-Ni-Cr纳米晶镀层的制备及性能研究

采用脉冲电沉积方法从Cr³⁺溶液中制备Fe-Ni-Cr纳米晶合金镀层,利用SEM,EDS和XRD对Fe-Ni-Cr合金镀层的表面形貌、化学组成和晶粒结构进行观察;利用电化学工作站对镀层进行极化曲线测试并与传统的304不锈钢进行对比。结果表明：电沉积镀层为纳米晶,无裂纹,表面光亮,晶粒尺寸大多分布在10~40 nm之间,镀层主要元素成分含量Cr为25.52%,Fe为59.61%,Ni为6.55%,与传统304不锈钢相比, Fe-Ni-Cr纳米晶镀层在5%的H₂SO₄溶液的自腐蚀电位提高了近30 mV,自腐蚀电流密度降低了近1/8,维钝电流降低了近1/10。因此,Fe-Ni-Cr纳米晶合金镀层表现出更好的耐蚀性。     

脉冲电沉积WC-Co-Ni镀层的制备及性能研究

目的提高WC-Co-Ni纳米晶复合镀层的综合性能。方法利用脉冲电沉积法制备WC-Co-Ni纳米晶复合镀层,分析镀层的结构、表面形貌及元素成分,测试镀层的显微硬度。对WC-Co-Ni纳米晶复合镀层和304不锈钢进行5%(质量分数)H2SO4溶液浸泡实验,计算腐蚀速率,对比其耐蚀性。结果当脉冲参数为阴极电流密度5 A/dm2、脉冲占空比50%、脉冲频率2000 Hz时,施镀2 h制备的WC-Co-Ni复合镀层为纳米晶结构。镀层表面平整、光亮,无裂纹,由立方晶型的Ni、六方结构的WC和立方晶型的Co组成,WC-Co颗粒均匀弥散在纳米晶Ni镀层内,且m(Ni)∶m(W)∶m(C)∶m(Co)=6∶2∶1∶1。WCCo纳米颗粒起到了促进形核的作用,晶粒尺寸大多分布在20 nm左右。WC-Co纳米颗粒对镀层起到了弥散强化作用,使复合镀层的显微硬度达到600HV。在浸泡腐蚀实验中,随着温度从20℃升高至80℃,复合镀层的腐蚀速率增加缓慢,20℃下的腐蚀速率仅为0.4192 mm/a,80℃下的腐蚀速率也低于20mm/a。结论脉冲电沉积法制备的WC-Co-Ni纳米晶复合镀层硬度高于传统的不锈钢材料,耐蚀性也优于304不锈钢,综合性能较好。     

深度轧制技术制备的纳米晶金属板材腐蚀性能研究进展

概述了目前已提出的几种纳米晶金属材料制备技术和不同纳米晶金属材料腐蚀研究进展。介绍了深度轧制技术制备纳米晶金属板材,阐述了该技术制备的纳米晶金属板材(工业纯铁、304不锈钢和工业纯铝)腐蚀性能研究进展。与相应的普通金属材料相比,深度轧制技术制备的这三种纳米晶金属材料在不同腐蚀环境(溶液、熔盐和高温气体)中耐腐蚀性能(局部腐蚀和均匀腐蚀)提高。大量纳米晶及其相应普通金属材料的腐蚀实验结果表明,传统的材料微观结构参量(成分及其分布、晶粒尺寸、位错密度和残余应力等)不是腐蚀性能的本征参量。提出了从金属材料价电子结构和氧化膜电子结构角度理解金属材料腐蚀性能及其相关腐蚀机理,并在现有工作基础上提出金属材料电化学腐蚀本征参量的概念。     

脉冲电沉积WC-Co-Ni镀层的制备及性能的研究

目的采用脉冲电沉积的方法制备碳化钨-钴-镍(WC-Co-Ni)纳米晶复合镀层。方法通过XRD,SEM,EDS和硬度分析等手段对镀层的结构、表面形貌、元素成分、显微硬度进行测试,最后采用浸泡实验的方法对WC-Co-Ni纳米晶复合镀层和304不锈钢在5% H₂SO₄溶液进行腐蚀速率计算。结果结果表明：当脉冲参数为阴极电流密度5A/dm₂,脉冲占空比50%,脉冲频率2000Hz时,施镀时间2h,制备的WC-Co-Ni复合镀层为纳米晶结构,WC-Co纳米颗粒起到了促进形核作用,晶粒尺寸大多分布在20nm左右;WC-Co纳米颗对镀层起到弥散强化作用,使复合镀层的显微硬度为600HV,高于传统的不锈钢材料(210HV);浸泡试验结果表明,WC-Co-Ni复合镀层的耐蚀性优于304不锈钢,温度由20℃～80℃,复合镀层腐蚀速率变化缓慢,20℃腐蚀速率仅为0.4192mm/a,80℃也低于20mm/a。镀层表面平整、光亮无裂纹.结论镀层由立方晶型的Ni,六方结构的WC和立方晶型的Co组成,WC-Co颗粒均匀弥散在纳米晶Ni镀层内并且镍、钨、碳与钴的原子重量百分比为6:2:1:1。     

0Cr18Ni9不锈钢表面纳米化对耐蚀性的影响

对0Cr18Ni9不锈钢采用超音速微粒轰击(Supersonic Fine Particles Bombarding,SFPB)进行表面纳米化处理,利用X射线衍射仪和透射电镜对试样表面形成的纳米品组织进行了检验.对试样表面进行了点蚀试验和动电位极化曲线测试,用扫描电镜对点蚀试样表面形貌进行了观察与分析.结果表明,超音速微粒轰击使试样表面层形成平均尺寸约20 nm的纳米晶组织,表面纳米化可以明显改善0Cr18Ni9不锈钢样品在3.5%NaCl溶液中的动电位极化特性,大大提高其抗氯离子腐蚀性能.     

304不锈钢表面CrAlN涂层制备及其耐腐蚀性能研究

采用电弧离子镀膜技术在单晶硅和304不锈钢表面制备了CrN、CrAlN涂层，对涂层的微观结构、表面形貌、机械性能及在人工海水中的耐腐蚀性能进行了研究。通过XRD、SEM对涂层的微观结构及表面形貌的研究结果表明：CrAlN涂层具有更少的表面缺陷和内部大颗粒，截面有着更致密的结构，CrN涂层沿CrN(200)择优生长，而CrAlN涂层则沿CrN(111)择优生长。对CrN、CrAlN涂层及304不锈钢基底的摩擦系数测试表明：CrAlN涂层的摩擦系数均比CrN涂层和304不锈钢的摩擦系数低。对304不锈钢基底及涂层在人工海水中的电化学极化曲线、Nyquist图进行的测试结果表明：CrAlN涂层的容抗弧半径远大于CrN涂层以及304不锈钢，其腐蚀电流密度与自腐蚀电位与CrN涂层相当，均比304不锈钢表现更为优异。     

304钢表面激光熔覆Stellite12钴基涂层组织及腐蚀性能

目的 对304不锈钢表面强化处理来提高其耐腐蚀性能。方法 使用激光熔覆技术将Stellite12涂层制备在304钢基体上。使用光学显微镜(OM)、扫描电子显微镜(SEM)、能谱仪(EDS)、X射线衍射(XRD)、三电极电化学工作站对涂层显微组织、元素分布、物相、电化学腐蚀行为进行测试与分析,并对涂层和304不锈钢的耐腐蚀性能进行了对比分析。结果 涂层物相主要由面心立方结构a-Co固溶体、CoCx等化合物组成。由于温度梯度和凝固速度的不同,熔覆层截面下、中、上部呈现出了不同的组织形貌特征:依次由平面晶、胞状晶、树枝晶、细小树枝晶组成。涂层枝晶间为Co和碳化物的共晶组织,枝晶内主要为a-Co的初生相。在进行电化学腐蚀后,涂层的自腐蚀电位为?504.5 mV,304钢的自腐蚀电位为?579.7 mV,涂层的腐蚀电位较304钢偏正,比304钢耐腐蚀。涂层表面出现了腐蚀点,腐蚀点位分布均匀、且程度较轻。304钢表面发生了严重的腐蚀,明显可见深度和面积较大的腐蚀孔洞。结论 Stellite12合金涂层能够有效地提高304不锈钢表面耐腐蚀性能。     

Influence of metal ions on the formation of artificial zinc rusts

The artificial rust particles were prepared from ZnCl₂ solutions dissolving Al(III), Fe(III), Fe(II), Ni(II), Co(II) and Mg(II) at different atomic ratios from 0 to 0.3 in metal/Zn. With increasing metal/Zn the crystal phases of the products turned following as ZnO → a mixture of ZnO and Zn₅(OH)₈Cl₂ · H₂O (ZHC) → ZHC. Al(III) most facilitated the formation of ZHC but Mg(II) and Fe(III) produced no ZHC. The morphology of the formed particles varied following as agglomerate → fine → rod → sheet → irregular with the increase of metal/Zn. The sheet and irregularly shaped particles were identified as ZHC and the other particles as ZnO.     

Effect of dislocation density on the low temperature aging behavior of an ultra low carbon bake hardening steel

Strain aging was studied in an ultra low carbon (ULC) steel with a total carbon content of 20 ppm (wt.%) in order to identify the process stages and mechanism of bake hardening in this type of steel. The effects of dislocation density, varied by means of uniaxial tensile prestraining (1–10%) on the aging kinetics were investigated within an aging temperature range of 50–170°C. The aging was evaluated by means of strength measurements and the determination of interstitial carbon content after aging using a piezoelectric composite oscillator operating at 40 kHz. The interaction between interstitial carbon and dislocations was examined through amplitude dependent internal friction measurements. The influence of dislocation density on the aging behavior have been discussed with reference to the kinetics and mechanism of the aging process.     

A corrosion study of the main constituent phases of AZ91 magnesium alloys

The different constituents of an AZ91 alloy (α,β, and MnAl phases) were synthesized and their corrosion resistance was studied by electrochemistry in ASTM D1384 water, pH 8.3. The pure phases were characterised through the corrosion potential, the polarisation resistance, and polarisation curves, then systematically coupled to assess the galvanic corrosion occurring in the AZ91 alloy. The aluminium content of the oxide film was obtained by X-ray photoelectron spectroscopy measurements. The corrosion rate of the α solid solution alloys depends closely on their Al content. Aluminium enhances the corrosion resistance of the α-phase through the formation of an Al enriched superficial layer. The β-phase is 150 mV nobler than the α-phase, but their corrosion rates are similar. The galvanic currents are low (below 20 μA cm⁻²) whatever the implemented couples and close to the corrosion current previously measured for the AZ91 alloys.     

Effect of solution heat treatment on galvanic coupling between intermetallics and matrix in AA7075-T6

Susceptibility to localised corrosion is strongly affected by heat treatments performed on Al-Zn-Cu-Mg alloys. In order to study how galvanic coupling between intermetallics and matrix is affected by solution heat treatment, AA7075-T6 and solution heat treated AA7075 have been characterised by means of scanning electron microscopy and scanning Kelvin probe force microscopy. Solution heat treatment strongly increased the Volta potential difference between the intermetallics and the surrounding matrix showing a strong increase in galvanic coupling. This is explained by Zn and Mg enrichment of the matrix caused by dissolution of strengthening particles during solution heat treatment.     

硬质合金Hc、Com、D、HV_3的初步探讨

通过研究硬质合金的矫顽磁力、钴磁、密度和硬度,阐述了这些性能之间的相互关系,以及影响这些性能的主要原因,说明了其对生产实践中质量控制的重要意义。     

Characterizing corrosion behavior under atmospheric conditions using electrochemical techniques

AC and DC electrochemical experiments were performed as a function of humidity and contaminant concentration in an effort to identify the range of atmospheric environments where corrosion processes could be detected and possibly quantified. AC measurements exhibited two time constants at 25% relative humidity (RH), possibly indicating the ability to resolve both electrolyte resistance and interfacial impedance. Galvanic current measurements were sensitive to the presence of Cl_2(g) at 30% RH and electrochemical transients were detected at both 30% and 50% RH levels, also indicating sensitivity to interfacial processes. Higher humidity levels allowed better quantification due to decreasing electrolyte and interfacial impedances.     

A study on the deactivation of an IrO2–Ta2O5 coated titanium anode

The deactivation of an IrO₂–Ta₂O₅ coated titanium anode was studied during an accelerated life test at 2 A cm⁻² in 1 mol dm⁻³ H₂SO₄ solution using CV, EIS, SEM and EDX. The changes of voltammetric charge, double layer capacitance, oxide film resistance and charge transfer resistance of oxygen evolution with time during the electrolysis were monitored. The morphology and surface composition of the oxide anode before and after electrolysis test were analysed. A comprehensive process of deactivation of the oxide anode was proposed based on the test results and analysis.     

Electrochemical behaviour of amorphous and nanoquasicrystalline Zr-Pd and Zr-Pt alloys in different environments

The corrosion behaviour of melt spun amorphous and nanoquasicrystalline Zr₇₀Pd₃₀ and Zr₈₀Pt₂₀ alloy ribbons has been investigated using potentiodynamic polarization study in NaCl, H₂SO₄ and NaOH solutions at different concentrations. The amorphous and nanoquasicrystalline alloys show better corrosion resistance than Zr in all the solutions studied. Both the alloys are susceptible to chloride attack and pitting has been observed. Complete passivation has been observed in H₂SO₄, while gradual break down of passivating layer occurs in NaOH. In general, nanoquasicrystalline state in both the alloys shows better corrosion resistance than amorphous state in all the solutions studied.     

加速发展我国的快速成形技术

介绍了第二届北京国际快速成形及制造会议概况，分析了快速成形（RP）技术的发展趋势，指出RP技术研究领域的重大进展及学科发展的主攻方向是：由RP向快速制造（RM）发展，由RP向快速模具（RT）发展，RP技术在生物医学领域的应用。     

Corrosion behaviour of powder metallurgical and cast Al-Zn-Mg base alloys

The behaviour of Al-Zn-Mg base alloys produced by powder metallurgy and casting has been studied using potentiodynamic polarisation in 0.3% and 3% NaCl solutions. The influence of alloy production route on microstructure has been examined by scanning electron microscopy, Auger electron spectroscopy and secondary ion mass spectrometry. An improvement in performance of powder metallurgy (PM) materials, compared with the cast alloy, was evident in solutions of low chloride concentration; less striking differences were revealed in high chloride concentration. Both powder metallurgy and cast alloys show two main types of precipitates, which were identified as Zn-Mg and Zr-Sc base intermetallic phases. The microstructure of the PM alloys is refined compared with the cast material, which assists understanding of the corrosion performance. The corrosion process commences with dissolution of the Zn-Mg base phases, with the relatively coarse phases present in the cast alloy showing ready development of corrosion.