玻璃钼电极的纯度对其抗侵蚀性能的影响

对比了不同纯度钼电极在熔融态玻璃中的腐蚀特性，分析了钼电极在玻璃液中腐蚀的原因。结果表明，钼电极的纯度越高，其抗腐蚀特性越强；钼电极在通电情况下的动态腐蚀将显著快于静态腐蚀；钼电极的腐蚀会在表面形成腐蚀坑。     

钢铁炉窑低温烟气中金属材料的耐腐蚀特性研究

采用自主设计的耐腐蚀特性试验台研究了钢铁炉窑低温烟气对五种常见金属材料的耐腐蚀特性,分析了不同烟气对金属材料腐蚀特性的影响。结果表明:金属材料在焦炉烟气中的耐腐蚀性强于热轧炉烟气;随着温度的升高,金属管材的锈层厚度和管壁膨胀率均逐步减少,20g的耐腐蚀性弱于ND钢;不锈钢的耐腐蚀性能由大到小依次为316L316304,其腐蚀速率随温度升高而下降,不锈钢在焦炉烟气中的腐蚀速率为32.5~146.2μm/a;金属管材在两种烟气中的腐蚀主要为硫腐蚀、碱金属腐蚀和煤焦油的腐蚀,但金属管材在两种烟气中的腐蚀表现形式有所不同。     

钒基合金腐蚀研究的现状和进展

本文介绍了国外对新型工程材料——钒基合金腐蚀研究的现状和进展。分别论述钒基合金在液态金属、液氦和水(蒸汽)等介质中的腐蚀特性,并讨论了非金属元素,如H、N和O对合金腐蚀特性的影响。     

金属材料在轧钢加热炉低温烟气中的耐腐蚀特性

为了解决钢铁炉窑低温烟气余热利用中换热器金属材料的腐蚀问题,采用自主设计的耐腐蚀特性试验台对五种常见金属材料进行了耐腐蚀特性研究,采用壁厚测试、SEM扫描电镜及EDS能谱检测仪对腐蚀层厚度及元素进行了检测,并对金属材料的腐蚀机理做了详细分析。结果表明:在轧钢加热炉低温烟气环境下,20g钢和ND钢均有较严重腐蚀,ND钢耐腐蚀性强于20g钢,三种不锈钢腐蚀情况差异不大且未见明显腐蚀,从微观检测结果看,不锈钢的耐腐蚀性能由大到小依次为316L316304,腐蚀速率为35~190μm/a,引起这些金属材料腐蚀的主要原因为酸结露腐蚀。     

南海海洋大气环境下铝合金腐蚀与防护研究

铝合金具有重量轻、比强度高、耐腐蚀、易加工、可回收利用等一系列优良特性,在海洋领域得到广泛应用。在南海海洋大气环境下,受其气候特性的影响,铝合金腐蚀类型遵循点蚀—晶间腐蚀—剥落腐蚀的演变过程。本文通过对铝合金腐蚀机理和现象的研究,重点介绍了铝合金在南海海洋大气环境下应用的腐蚀类型与防护措施。     

耐碱蚀稀土合金铸铁研究与发展概述

普通铸铁、0C r18N i9等材料在高温浓碱液中的腐蚀严重。基于碱腐蚀问题,概述了国内外各种耐碱蚀合金铸铁的腐蚀特性、发展及应用,并从稀土、镍、铬、铜合金元素及组织对腐蚀性能的影响方面,分析了稀土合金铸铁的研究状况和发展。     

铝及其合金的腐蚀与防蚀管理探讨

本文简要介绍了铝的腐蚀特性与腐蚀类型,并且基于此,阐述了铝及其合金的防蚀管理,希望能够为今后有关研究提供参考依据,并且希望能够促进铝及其合金的使用。     

高矿化度油田水中P110油管钢高温高压CO2腐蚀膜特征

从腐蚀产物膜特征角度,研究了高矿化度油田水中油套管钢的抗CO2腐蚀行为.结果表明,温度能够明显影响腐蚀产物膜的特性,在90～130℃的温度范围内随温度升高,腐蚀产物膜变得致密.110℃下腐蚀产物膜表现为疏松多孔,孔隙处易形成液体的滞留区,从而加重了P110管的点蚀.130℃下,腐蚀产物发生二次成膜,下层膜主要由FeCO3组成,上层膜则主要为Ca(Mn,Mg)(CO3)2.     

Q345R钢湿硫化氢预腐蚀低周疲劳行为

对Q345R钢在湿硫化氢环境中预腐蚀低周疲劳性能进行了研究,以硫化氢溶液的浓度和预腐蚀时间为环境因素.低周疲劳试验在MTS-809疲劳试验机上进行,对各试验组的结果数据进行回归分析,得到各试验组环境下Q345R钢的循环应力-应变曲线、应变-寿命曲线等低周疲劳特性.不同试验环境下的预腐蚀低周疲劳结果表明,材料循环应力应变响应特性不受环境因素影响,为循环硬化特性;预腐蚀时间因素对材料低周疲劳寿命的影响比硫化氢溶液的浓度因素显著.试样断口为典型的低周疲劳断裂形貌,裂纹扩展阶段为脆性准解理断裂特征.     

钕铁硼永磁材料腐蚀机理及表面防护技术现状

综合论述钕铁硼永磁材料的物相组成、腐蚀机理以及表面防护工作,阐述了钕铁硼永磁材料高温氧化、湿热吸氢和电化学腐蚀的腐蚀特性以及电镀、化学镀该领域应用现状以及这些技术的基本原理、技术特点、研究现状及发展趋势。     

Electrochemical Corrosion Behavior of Nd-Fe-B Sintered Magnets in Different Acid Solutions

Electrochemical corrosion behavior of Nd-Fe-B sintered magnets in nitric acid, hydrochloric acid, sulfuric acid, phosphate acid and in oxalic acid was studied. Potentiodynamic polarization curves and immersion time dependence of corrosion rates of Nd-Fe-B sintered magnets in different acid solutions were tested. Microstructures of corroded Nd-Fe-B sintered magnets were investigated by means of SEM and AFM. The results indicate that in strong acid solutions of similar hydrogen ion concentration, the corrosion current increases in the order of HCl 〉 H3SO4 〉 HNO3 solution and Nd-Fe-B sintered magnets are passivated in phosphate acid and oxalic acid. Within 25 min, the corrosion rates of Nd-Fe-B sintered magnets in H2SO4 and H3PO4 solutions show a declining trend with immersion time, while in HNO3 and HCl solutions the corrosion rates are rising. And in H2C2O4 solution, weight of the magnets increases. The brim of Nd-Fe-B sintered magnets is corroded rather seriously and the size of the magnets changed greatly in nitric acid. The surfaces of the corroded magnets in the above mentioned acid solutions are all coarse.     

低失重烧结钕铁硼磁体的研究进展

烧结钕铁硼永磁材料被发明以来,以其优越的磁性能得到了广泛的应用,目前成为永磁产业的支柱。但是其耐腐蚀性能差,大大限制了其使用范围。因此,近20多年来如何改善其抗腐蚀性能成为烧结钕铁硼材料生产和使用的重要问题。总结了烧结钕铁硼腐蚀失重的机制,制备低失重烧结钕铁硼的方法和工艺,对如何提高烧结钕铁硼磁体的耐腐蚀性,降低腐蚀失重进行了综述。从磁体成分设计和微观结构方面总结了几条提高烧结钕铁硼磁体耐蚀性的原则,其关键是对晶界相的成分和微观结构进行合理的控制。     

Abnormal corrosion behavior of dual-main phase sintered(Ce,Nd)-Fe-B magnets in different sodium solutions

Sintered(Ce,Nd)-Fe-B magnets with high cost performance were prepared by substituting of Ce for Nd with the dual-main phase method.The corrosion behaviors of dual-main phase sintered(Ce_xNd_(1-x))_(30)Fe_(69)B_1(x=0.15 wt%,0.3 wt%) magnets,which were named as Ce15 and Ce30,were studied in 3.5 wt% NaCl,6.6 wt% Na_2 SO_4 and 3.0 wt% NaOH aqueous solutions,respectively.The galvanic corrosion of Ce30 is stronger than that of Ce15.However,the mass loss value of Ce30 is smaller than Ce15 after free corrosion for 33 d in NaCl solution.In the other two solutions,all the results show that the corrosion resistance of Ce30 is better than that of Ce15.The scanning electron microscope results show that the crack and shedding of the magnetic phase of Ce30 is less than that of Ce15.Combined above,the abnormal corrosion behavior shows that Ce30 magnets perform better corrosion resistance than Ce15,and the degradation degree of magnetic phase mainly affects the corrosion resistance of magnets.     

Preparation and characterization of sodium silicate/epoxy resin composite bonded Nd-Fe-B magnets with high performance

As an organic binder for bonded Nd-Fe-B magnets, epoxy resin(EP) has poor heat resistance but good moisture resistance, while sodium silicate(SS) has poor moisture absorption but better heat resistance and corrosion resistance. In order to improve high temperature stability and decrease moisture absorption of bonded Nd-Fe-B magnets, EP/SS composites were applied as the binder to prepare bonded Nd-Fe-B magnets. The magnetic properties, moisture absorption, corrosion resistance, compressive strength and microstructure of composite bonded magnets were investigated. The results show that EP/SS bonded magnets can obtain excellent magnetic properties at room temperature, and even useable magnetic properties a thigh temperature environments at 200°C. EP/SS composite binder effectively improves heat resistance and corrosion resistance of bonded Nd-Fe-B magnets, and reduces the hygroscopic properties. The molecule of sodium silicateis rigid and keeps it original shape at high temperature environments. In addition, SS in composite binder improves the mobility of the magnetic powders during the pre-pressing process, which makes the magnetic powders attain a more regular structure. These two factors will increase the mechanical properties. Moreover, sodium silicate in the composite binder can also cover the surfaces protecting the magnetic powders from oxidation and corrosion. EP in composite binder can cover SS surface to reduce the water absorption of SS as epoxy is a hydrophobic material. The EDX analysis shows that the composite binder has accumulated in the gaps of the magnet powders, which not only improves heat resistance and corrosion resistance, but also increases the mechanical properties. Therefore, EP/SS composite binder endows bonded Nd-Fe-B magnets excellent comprehensive properties.     

Microstructure and corrosion resistance of sintered NdFeB magnet modified by intergranular additions of MgO and ZnO

Microstructure and corrosion resistance of sintered Nd15Dy1.2Fe77Al0.8B6 and Nd22Fe71B7 magnets modified by intergranular addition of MgO and ZnO were investigated. Both the remanence and sintering density of the magnets increased slightly with intergranular additions of MgO and ZnO. There was a remarkable increase in coercivity of Nd22Fe71B7 after addition. Besides, the effects on magnetic properties and an improved corrosion resistance were observed. Compared with the native magnets without addition, corrosion potential of the magnets with MgO and ZnO additives was more positive and the current density in the anodic branch of the polarization curve was reduced. Corrosion resistance resulting from autoclave testing （2×10^5 Pa of steam pressure, 120 ℃） showed that the corrosion rate of NdFeB magnets reduced with the increase of additive amount. Microstructure observation revealed that MgO and ZnO additives were incorporated into the intergranular phases in the magnets. With the introduction of MgO and ZnO, more intergranular phase with high oxygen content was formed while keeping the volume fraction of all the intergranular phases almost unchanged, which may contribute to improved corrosion resistance. Furthermore, addition of MgO and ZnO refined the grain size of Nd22Fe71B7.     

烧结钕铁硼镀镍防腐性能比较

采用不同浇铸工艺和破碎工艺制备三种烧结钕铁硼磁体,对三种磁体及其电镀镍后的防腐性能进行了比较.研究发现,三种磁体电镀镍后的防腐性能不仅与镍镀层厚度有关,同时也与基体本身耐蚀性能有关.经对比分析,采用速凝薄带配合氢气破碎工艺制备的镀镍磁体防腐性能最佳.     

Rare earth passivation and corrosion resistance of zinc coated NdFeB magnets

Rare earth passivation was conducted on Zn coated NdFeB magnets by chemical reaction to enhance the corrosion resistance performance.Morphologies,micro structures and compositions of different passivated coatings were studied by X-ray diffraction,field emission scanning electron microscopy,and X-ray photoelectron spectroscopy,respectively.The corrosion behavior was evaluated by electrochemical measurement and neutral salt spray test.The results show that the rare earth passivation can enhance the corrosion resistance of Zn coated NdFeB magnets.When the concentration of cerium nitrate is 5 g/L,the passivated specimens can achieve the longest NSS time of 360 h,which is 144 h longer than that of the pristine Zn/NdFeB magnets.The passivation layer on the Zn coating surface contributes to the enhancement of the magnets’corrosion resistance.     

Improvement of coercivity and corrosion resistance of Nd-Fe-B sintered magnets by doping aluminium nano-particles

Nd-Fe-B permanent magnets with a small amount of Al nano-particles doping were prepared by conventional sintered method. Effect of Al content on magnetic property, corrosion resistance and oxidation properties of the magnets were studied. Investigation showed that the coercivity rose gradually, while the remanence decreased simultaneously with increase of Al doping amount. Further investigation revealed that most Al element diffused into the main phase and some Al element diffused into the Nd-rich phase. The autoclave test results showed that the corrosion rate of the magnets decreased with Al content increasing. After oxidation, the maximum energy product losses of the magnets with 0.0 wt.% and 0.2 wt.% Al nano-particles doping were 6.13% and 3.99%, respectively. Therefore, Al nano-particles doping was a promising way to enhance the coercivity and corrosion resistance of sintered Nd-Fe-B magnet.     

Nd取代对Pr-Nd-Fe-B烧结磁体耐腐蚀性的影响

以HAST加速寿命试验后磁体失重,以及在不同腐蚀介质中磁体动电位极化曲线为表征,研究稀土元素Nd取代Pr对烧结Pr-Nd-Fe-B磁体耐腐蚀性的影响.结果表明:用Nd完全取代Pr后,磁体失重减小,室温下在0.1 mol/L HCl溶液、3.0 % NaOH溶液、3.5 % NaCl溶液中腐蚀电位不同程度地正移,表明磁体耐腐蚀性得到改善.通过场发射扫描电子显微镜观察HAST试验后磁体的微观组织形貌发现,Nd取代Pr后,晶界分布变得更加连续、清晰,且晶界交隅处的富稀土相含量减少,从而延缓了晶界腐蚀速率,使磁体的总体耐腐蚀性得到提升.      

Superior corrosion resistance and corrosion mechanism of dual-main-phase (Ce15Nd85)30FebalB1M magnets in different solutions

The electrochemical corrosion behavior of both(Ce₁₅Nd₈₅)₃₀Fe_balB₁ M sintered magnets prepared with dual-main-phase method and N45-type magnets was studied in 3.5 wt% NaCl,1.1 wt% NaH₂ PO₄,and2.5 wt% NaOH solutions,respectively.The(Ce₁₅Nd₈₅)₃₀Fe_balB₁ M sintered magnets perform superior corrosion resistance than N45-type magnets in the tested solutions.In general,two ...