激光熔覆FeCrNiCoMoCuBSi高熵合金涂层的腐蚀磨损性能

利用激光熔覆技术在316L不锈钢表面制备了FeCrNiCoMoCuBSi高熵合金涂层,分析了其组织结构、硬度、摩擦磨损、电化学腐蚀和腐蚀磨损性能。结果表明,熔覆层成型良好,表面无裂纹、气孔等缺陷。熔覆层主要由FCC固溶体相组成,微观组织以“柳条状”树枝晶为主,结合区为平面晶,与基体呈良好的冶金结合。熔覆层的平均硬度为700 HV_0.2,约为基材的3.5倍。熔覆层在不同载荷下的摩擦系数均低于基材,磨损量小于基材,表现出明显优于基材的耐磨性。在3.5wt% NaCl溶液中,熔覆层自腐蚀电流密度为4.74×10^_-8A.cm^_-2,低于基材两个数量级,耐蚀性优异。在摩擦载荷与腐蚀耦合作用下,熔覆层开路电位发生负偏移,腐蚀倾向增大。随摩擦载荷增大,自腐蚀电位负移,自腐蚀电流密度增大,摩擦促进腐蚀作用增大。     

超高速与常规激光熔覆Fe基涂层微观组织及性能研究

目的 对比研究常规与超高速激光熔覆涂层的微观组织、相结构,明确涂层结构及性能间的构效关系。方法 以27SiMn为基体,分别采用常规和超高速激光熔覆技术制备Fe基涂层。采用扫描电镜(SEM)表征涂层的显微组织,用能谱仪(EDS)分析涂层的元素分布。采用X射线衍射仪(XRD)、光学显微镜(OM)和电子背散射衍射(EBSD)方法分析涂层的相组成。采用显微硬度计、电化学工作站等测试涂层的硬度分布及电化学特性。结果 常规与超高速激光熔覆涂层组织致密,均无明显气孔和裂纹等缺陷。相较于常规激光熔覆涂层,超高速激光熔覆涂层的晶粒更为细小,涂层成分接近粉末设计成分,晶内和晶间Cr元素分布更为均匀。2种工艺制备的涂层均由马氏体、铁素体和M型碳化物组成,但是超高速激光熔覆涂层所含马氏体和碳化物含量更低,使其硬度低于常规激光熔覆涂层。同时,与常规激光熔覆涂层相比,超高速激光熔覆涂层的自腐蚀电位由–0.56 V升高至–0.51 V,自腐蚀电流密度由1.3×10^–5 A/cm²显著降低至1.5× 10^–7 A/cm²。 结论 与常规激光熔覆相比,超高速激光熔覆涂层晶粒细小,成分均匀,具有更优异的耐腐蚀性能。与此同时,涂层的马氏体及碳化物含量更少,硬度更低。     

激光熔覆镍基合金磨损及电化学腐蚀性能研究

目的 为解决不锈钢零件在工程应用中表层由于磨损、腐蚀导致其使用寿命缩短的问题,修复和提升不锈钢表层的硬度、耐磨性及耐蚀性.方法 在总结前期大量实验数据及规律的基础上,采用激光熔覆法在304不锈钢表层制备无裂纹、熔覆质量良好的Ni60涂层.利用光学显微镜、扫描电镜、能谱仪、X射线衍射仪等设备,系统地研究了熔覆层组织的形貌、元素分布及物相结构.采用显微硬度计、摩擦磨损仪、电化学工作站等设备,测试熔覆层的硬度分布、磨损特性及电化学特性.结果 涂层具有均匀致密的微观结构,主要以固溶态γ-(Ni,Fe)、碳化物M23C6(M=Fe、Ni、Cr)、硼化物CrB组成,熔覆涂层的显微硬度约为基材的2.5倍,熔覆过程中,硬质增强相的形成是其硬度提升的主要原因.熔覆涂层的磨损率、磨损深度、磨损后表面单位面积的粗糙度(Sa)分别为基材的8.5％、69％、22.2％,与基材相比,涂层的耐磨性能明显更优.涂层的腐蚀速率比基材低2个数量级,涂层表面形成的致密钝化膜是耐蚀性好的主要原因.结论 熔覆质量良好的Ni60涂层,较304奥氏体不锈钢基材有更加优异的硬度、耐磨及耐腐蚀性能.     

ER8车轮钢激光熔覆涂层在酸雨环境下的磨损与腐蚀性能分析研究

目的 提高ER8高速车轮钢的耐磨和耐腐蚀性能,增强车轮使用寿命。方法 在ER8车轮钢表面制备出Fe基合金粉末和Co基合金粉末2种涂层。借助SEM、XRD、纳米压痕仪等表征设备分析涂层的金相组织形貌、物相种类和纳米硬度。利用MFT-EC4000往复电化学摩擦磨损试验仪将试样置于酸雨溶液进行摩擦磨损试验及电化学腐蚀试验。结果 涂层表面组织致密均匀,形成了良好的冶金结合,Fe基与Co基合金涂层分别呈现出“胞状”与“蜂窝状”,无明显孔洞、裂纹等缺陷。基体在低频(1 Hz)下发生轻微的磨粒磨损,中高频(2、4 Hz)下出现了严重的剥落、点蚀现象,其磨损机理主要为粘着磨损、氧化磨损和磨粒磨损,涂层磨损区域则无明显腐蚀与剥落现象。在高频下,Fe基涂层和Co基涂层的磨损率分别比基体减少46.10×10^–5 mm³/(N.m)和39.85×10^–5 mm³/(N.m)。同时,涂层的阻抗值显著提高,极化曲线测试结果显示,Fe基涂层、Co基涂层和基材的自腐蚀电位分别为–0.522、–0.381、–0.603 V,腐蚀密度分别为3.916、0.312、5.483 μA/cm²。结论 修复后的车轮钢样品的耐磨损性能与耐腐蚀能力得到不同程度提高,相比之下,耐磨损方面Fe基合金涂层表现得更为优异;耐蚀性方面,Co基合金涂层略强于Fe基涂层。     

FeCrNiMo激光熔覆层组织与电化学腐蚀行为研究

目的 研究所设计FeCrNiMo激光熔覆层的组织结构及电化学腐蚀行为，用于解决液压支架表面防护与修复问题。方法 采用激光熔覆技术在27SiMn钢表面制备FeCrNiMo合金熔覆层，通过XRD、光学显微镜和SEM表征其微观组织结构，利用动电位极化与交流阻抗谱技术研究熔覆层电化学腐蚀行为。结果 在适宜工艺条件下实现了单道熔覆层厚度达2 mm以上，且无明显气孔、裂纹等缺陷。熔覆层具有胞状枝晶组织特征，枝晶内为马氏体，晶间富Cr、Mo的铁素体有效缓解了马氏体相变的高应力，达到了较好的强韧化匹配。熔覆层在3.5%NaCl和0.5 mol/L H2SO4溶液中均呈现出明显的钝化行为，钝化区间宽度分别为300 mV和1310 mV，自腐蚀电位分别为–140.2 mV和2.3 mV，自腐蚀电流密度分别为5.0×10^–8A/cm²和1.3×10^–3 A/cm²，极化电阻分别为3.5×10⁵ ?.cm²和6261.4 ?.cm²，具有较为优异的耐腐蚀性能，且显著优于基体材料，但其双相组织特征易导致微区发生选择性腐蚀。结论 所设计的FeCrNiMo合金及相应激光熔覆工艺，满足实际工程对于熔覆层高效制备、成形质量及耐蚀性的要求，可用于液压支架表面防护与修复。     

1Cr18Ni9Ti 不锈钢表面电火花熔覆 WC 涂层特性研究

目的研究1Cr18Ni9Ti不锈钢经电火花强化后,WC涂层的显微组织和性能。方法采用电火花熔覆技术在不锈钢1Cr18Ni9Ti基体表面制备WC熔覆层,并分析熔覆层的表面形貌、显微组织、显微硬度、耐磨性,采用线性极化法研究熔覆层在3.5%(质量分数)Na Cl腐蚀溶液中的耐腐蚀性能。结果熔覆层组织均匀、连续、致密,与基体呈冶金结合。显微硬度最大值达到1680HV0.3,平均值为1336HV0.3,比不锈钢基材提高了4倍,耐磨性是不锈钢基材的4倍。在3.5%Na Cl腐蚀溶液中,熔覆层的自腐蚀电位较不锈钢减小了约165 m V,击破电位低于不锈钢基材,维钝电流密度高于不锈钢基材。结论熔覆层具有高硬度和高耐磨性能,磨损机理主要是粘着磨损和磨粒磨损,但在3.5%Na Cl腐蚀体系中,耐腐蚀性能低于1Cr18Ni9Ti不锈钢。     

球墨铸铁表面激光熔覆Ni-Co复合涂层的耐腐蚀及高温摩擦学性能

为降低球墨铸铁激光熔覆过程中白口组织的含量,改善其高温摩擦学性能和耐腐蚀性能,采用激光熔覆技术,通过添加 Ni 基过渡层在球墨铸铁表面制备 Co 基涂层。利用 XRD、SEM、EDS 表征不同熔覆层的物相组成、微观结构。采用高温摩擦磨损试验机测试不同温度下 Co 基涂层与球墨铸铁的摩擦磨损性能,分析 Co 基涂层在不同温度下的磨损机理。利用电化学工作站测试 Co 基涂层与球墨铸铁的耐腐蚀性能。结果表明：Ni 基过渡层的物相为 γ-Ni 固溶体和 Ni₃Si 陶瓷相。Co 基涂层主要由 γ-Co 固溶体和 Cr₇C₃陶瓷相构成。Ni 基过渡层的添加抑制了基材中 C 元素扩散,降低了结合界面处白口化趋势。由于 Cr₇C₃陶瓷相的强化作用,Co 基涂层的显微硬度为球墨铸铁基材的 2.1 倍。与球墨铸铁基材相比,当温度高于 200 ℃时, Co 基涂层在与 Si₃N₄配副对磨时表现出较低的平均摩擦因数与磨损率。在中低温条件下 Co 基涂层与 Si₃N₄ 配副对磨时的磨损机制为黏着磨损与磨粒磨损,高温条件下的磨损机制为形成连续光滑的氧化层起到减摩抗磨的作用。Co 基涂层表现出更高的自腐蚀电位(?362.36 mV)和更低的自腐蚀电流密度(13.95 nA·cm^?2 )。所制备的 Ni-Co 复合涂层能有效提高球墨铸铁表面的高温摩擦学性能和耐腐蚀性能,在发动机领域具有较好的应用前景。     

Laser Cladding Fe-Cr-Si-P Amorphous Coatings on 304L Stainless

采用激光熔覆技术在304L不锈钢基体表面制备了Fe-Cr-Si-P非晶复合涂层。利用光学显微镜(OM)、X射线衍射仪(XRD)、扫描电子显微镜(SEM)、电化学测试系统和摩擦磨损试验机等分析了涂层的组织结构、相组成、耐蚀及耐磨等性能。研究结果表明,激光熔覆层组织主要由表层"梅花"形树枝晶区,中心非晶区和树枝晶结合区组成,熔覆层与基体呈现良好的冶金结合。熔覆层中除了非晶相外,还有少量Fe3P和Fe2Si等金属间化合物相。涂层的硬度HV0.2约为8000 MPa,是基体硬度的4倍;腐蚀电位Ecorr和自腐蚀电流密度icorr分别为–449.3 mV和–4.34μA/cm2;在100 N载荷下摩擦系数仅为0.076,具有较好的综合性能。     

低碳钢表面激光熔覆不锈钢的组织和性能

采用JHM-1GY-400型脉冲Nb∶YAG固体激光器和316L不锈钢粉末在20低碳钢表面制备了激光熔覆层。利用OM、XRD、SEM等表征方法分析了不锈钢熔覆层的物相组成和显微组织,并分别利用旋转摩擦试验机和电化学工作站对熔覆层和基材的耐磨损和耐腐蚀性进行了研究。试验结果表明,不锈钢熔覆层厚度约为50 μm,由γ相(奥氏体)和α相(铁素体)组成,其显微组织主要包括细小的树枝晶、粗大的胞状晶以及平面晶;不锈钢熔覆层表面硬度约为基材的2倍,摩擦因数比基材低0.0418,磨损量更低,不锈钢熔覆层比基材具有更高的耐磨性。与基材相比,不锈钢熔覆层具有更低的自腐蚀电流和更高的自腐蚀电位,其耐腐蚀性能更优异。     

激光熔化沉积CoCrNiNbW高熵合金耐磨及腐蚀性研究

目的 解决Q235钢材料在实际应用中由于磨损、腐蚀导致使用寿命缩短问题,提升Q235钢表面的硬度、耐磨性和耐蚀性。方法 利用激光熔化沉积技术在Q235钢表面制备无裂纹CoCrNiNbW高熵合金涂层。采用扫描电子显微镜、X射线光谱仪、光学显微镜表征其微观组织结构、元素分布和物相成分;采用显微硬度计、试块-试环摩擦磨损试验机分别测试高熵合金涂层和Q235钢的显微硬度和耐磨性能,研究涂层的强化机制和磨损机理;采用电化学工作站测试分析高熵合金涂层和Q235钢的电化学腐蚀行为,研究涂层的耐蚀性和腐蚀机制。结果 CoCrNiNbW高熵合金涂层的微观组织主要由等轴晶组成,涂层中部和底部存在未熔化Nb和W颗粒,起强化相作用;主要物相由富含Co、Ni的FCC相及富含Nb的BCC相组成;高熵合金涂层的平均显微硬度为800HV0.2,约为基材的4倍;涂层的磨损机制以磨粒磨损为主,磨损率为2.315´ 10^–5 g.m^–1,约为基材的1/5;在质量分数3.5%的NaCl溶液中,高熵合金涂层具有更好的耐腐蚀性,腐蚀电阻约为基材的8倍。结论 高熵合金涂层的显微硬度、耐磨性和耐腐蚀性较Q235钢基材有很大提升。     

新型的治疗阿尔茨海默氏症药物(1-二甲基磷酰基-2,2,2-三氯)-乙基-1-醇烟酸醋对体外神经细胞的作用

目的: 观察本实验室合成的一种治疗阿尔茨海默氏症(AD)的药物(1-二甲基磷酰基-2, 2, 2 -三氯)-乙基^-1-醇烟酸醋(NMF),对体外培养的皮层神经细胞活性的影响以及对海人藻酸(KA)所致的神经损伤的保护作用。方法: 采用体外培养皮层神经元的方法,解剖分离 15 d胚胎小鼠皮层神经细胞, 接种于 96孔板,48 h 后加药并培养 72 h,以 MIT 法 观察 NMF 对小鼠皮层神经细胞活性的影响;同时将接种于 24 孔板的细胞预先给予 NMF,d 3 时加或不加KA处理后,以台盼蓝染色鉴别并计数死、活细胞,可得出细胞的存活率。结果: NMF 明显促进胎鼠皮层神经元活性,其中 NMF1、0. 1、10nmol·L^-1促进神经元活性增殖率分别高达 34.7%、37.4%、36. 7%, NMF 明显促进正常胎鼠皮层神经元存活卒,与对照组比较,10nmol·L^-1 NMF 对皮层神经元的存活率分别提高 39.3%、73.5%。 NMF能显著 对抗 KA 所致的神经元损伤,与 KA 损伤组相比, NMF0.1、10、10nmol·L^-1对损伤皮层神经元的保护率分别为 77.30%、80.10%、84.15%。结论: NMF 明 显促进胎鼠皮层神经元的洁性、提高正常皮层神经元,的存活卒,并能有效地保护KA所致的神经元损伤,提示 NMF 是一种很有潜力的治疗 AD 的药物。     

Three-Dimensional Growth of Coherent Ferrite in Austenite: A Molecular Dynamics Study

Coherent second phase often exhibits anisotropic morphology with specifi c orientations with respect to both the second and the matrix phases. As a key feature of microstructure, the morphology of the coherent particles is essential for understanding the second-phase strengthening eff ect in various industrial alloys. This letter reports anisotropic growth of coherent ferrite from austenite matrix in pure iron based on molecular dynamics simulation. We found that the ferrite grain tends to grow into an elongated plate-like shape, independent of its initial confi guration. The fi nal shape of the ferrite is closely related to the misfi t between the two phases, with the longest direction and the broad facet of the plate being, respectively, consistent with the best matching direction and the best matching plane calculated via the Burgers vector content(BVC) method. The strain energy calculation in the framework of Eshelby's inclusion theory verifi es that the simulated orientation of the coherent ferrite is energetically favorable. It is anticipated that the BVC method will be applicable in analysis of anisotropic growth and morphology of coherent second phase in other phase transformation systems.     

Effect of Short-Time Aging on the Pitting Corrosion Behavior of a Novel Lean Duplex Stainless Steel 2002

The effect of short-time aging in the temperature range between 400 and 1000 °C on the pitting corrosion behavior and mechanical property of a novel lean duplex stainless steel(LDSS) 2002 was investigated through the potentiostatic critical pitting temperature(CPT) tests and the Charpy impact tests. Both the pitting corrosion resistance and the toughness of aged specimens degraded due to the precipitation of detrimental secondary phases and the most significant reduction of CPT and impact energy emerged at 650 °C concurrently. The CPT of LDSS 2002 specimen aged at 650 °C decreased by 28 °C, and the impact energy dropped from 69 to 29 J/cm~2 compared with the solution-annealed sample. Transmission electron microscopy characterization showed that the main precipitates in LDSS 2002 were Cr_2N and M_(23)C_6 along the ferrite–austenite grain boundaries.     

INTRODUCTION TO PATENTS

The invention provides a method of making a mold which can reduce SOx generation rate while preventing decrease in hardening rate in the case of using sulfuric acid for a hardener composition. The method has a mixture step in which fire-resistant particles, a hardener composition and a binder composition are mixed to obtain a composition for a mold. The hardener composition contains sulfuric acid. In the mixture step, sodium carbonate is added. A molar ratio of the sulfuric acid to the sodium carbonate is 0.5 or more and 4.0 or less.     

China Foundry Week 2014

China Foundry Week, hosted by the Foundry Institution of Chinese Mechanical Engineering Society （FICMES） each year, is a large academic event in China. It is one of the ten high-impact activities sponsored by the Chinese Mechanical Engineering Society.     

17th Conference of Hydrodynamic and Electromechanical Control Engineering Call for papers

正1.Contents In order to promote the academic exchanges and technical communication of the research in the field of fluid power transmission and control,fluid control engineering specialized committee of the Chinese Society of Theoretical and Applied Mechanics will hold the 17th Conference of Hydrodynamic and Electromechanical Control Engineering on July 27-29,2014 in Tibet,Lhasa city.     

Information for Contributors

正The Transactions of Nonferrous Metals Society of China,founded in 1991 and sponsored by The Nonferrous Metals Society of China,is published monthly now and mainly contains reports of original research which reflect the new progresses in the field of nonferrous metals science and technology,including mineral processing,extraction metallurgy,metallic materials and heat treatments,metal working,physical metallurgy,powder metallurgy,with the emphasis     

Preface

<正>We are pleased to present this Special Issue of Transactions of Nonferrous Metals Society of China containing selected papers from the First Asian Conference on Aluminum Alloys(ACAA-2013),held in Beijing,China,13–17 October 2013.This conference has been initiated,with approval of     

Information for Contributors

The Transactions of Nonferrous Metals Society of China, founded in 1991 and sponsored by The Nonferrous Metals Society of China, is published monthly now and mainly contains reports of original research which reflect the new progresses in the field of nonferrous metals science and technology, including mineral processing, extraction metallurgy, metallic materials and heat treatments, metal working, physical metallurgy, powder metallurgy, with the emphasis on fundamental science. It is the unique preeminent publication in English for scientists, engineers, under/post-graduates on the field of nonferrous metals industry. This journal is covered by many famous abstract/index systems and databases such as SCI Expanded, Ei Compendex Plus, 1NSPEC, CA, METADEX, AJ and JICST.     

Formulas of Tension of Continuous Rolling Process

The development of computer controlled continuous rolling process calls for a mathematical expression that can express the inequality condition of "constant flow". Tension is the link of the continuous rolling process. From the condition of dynamic equilibrium, a differential equation of tension is given out. On the basis of the physical rules established from the industrial practice and experimental studies, the law of volume constancy, the linear relation of forward slip and tension, the state equation of continuous rolling, the formula of dynamic tension, and the formula of static tension have been obtained. These formulae reflect the functional relations between tensions, thickness, roll velocity, and time in the continuous rolling process. It is implied that the continuous rolling process is a gradually steady, controllable, and measurable dynamic system. An assumption of predicting the thickness of a steel plate using these tension formulae is also put forward.