纯钛Mo-N共渗改性层在H2SO4溶液中的腐蚀行为研究

采用等离子表面合金化技术对纯钛进行Mo—N共渗。利用电化学腐蚀系统对改性层及基体在0．5mol／L的H2S04溶液中进行电化学对比实验。实验结果表明，纯钛表面Mo—N共渗可以得到致密、均匀的表面改性层，改性层由沉积层和扩散层组成，厚度为4μm；改性层表面由钼氮化合物Mo16N7组成；Mo—N改性层提高了纯钛在0．5mol／L的H2SO4溶液中的耐蚀性，并对改性层在稀硫酸介质中腐蚀机理进行了初步探讨。     

H13钢表面电火花改性及其耐蚀性能研究

利用电火花表面强化技术,在H13钢表面制备钛改性层,借助图像分析仪、辉光放电光谱分析仪(GDOES)和X射线衍射仪对改性层组织结构进行分析,并借助多重扫描电位法研究其耐腐蚀性能.结果表明,改性层均匀连续,与基体为冶金结合,Ti元素呈梯度分布;与H13钢基材相比,改性层在0.6 mol/L的NaCl溶液中的自腐蚀电位约为-371 mV,较基材的-472 mV有大幅提高;在0.5 mol/L的硫酸溶液中的耐蚀性也相应得到改善.     

导电性超细铜粉制备方法研究

利用自制防氧化剂对已氧化超细铜粉表面改性,研究了氧化层去除工艺,分析了防氧化剂浓度和制备温度对处理结果的影响,确定最佳工艺是以5%稀硫酸作为酸洗剂,防氧化剂浓度为1%,反应温度为60℃.试验发现铜粉红外反射谱图中有防氧化剂特征峰,推测防氧化剂通过化学键和作用在铜粉表面生成一层厚度适中的保护膜,抑制铜粉氧化,但并不影响导电性.     

材料表面技术的研究及双辉技术在防腐蚀中的应用

文章简要介绍了化学气相沉积（CVD）、物理气相沉积（PVD）、高能束表面改性及其它表面处理技术的新进展,讨论了利用双辉离子渗技术处理后碳钢对酸液的耐腐蚀性能.经双辉技术处理后的碳钢试样在稀硫酸和富液中的耐腐蚀性能显著提高.     

纯钛表面渗Mo改性层在模拟人工体液中的腐蚀行为研究

为了提高纯钛表面的耐磨性,并检测改性层在模拟人工体液中的耐蚀性能,利用等离子表面合金化技术在纯钛表面渗Mo,对改性层的组织、成分进行测试,并对其在模拟人工体液中的耐蚀性进行了研究.结果表明:表面改性层由渗层及扩散层组成,改性后的钛材不但表面硬度显著提高,在模拟人工体液中的耐蚀性也得到改善.     

低铬铸铁铸渗WC颗粒的工艺研究

为进一步提高低铬铸铁的耐磨性,利用铸渗工艺采用膏块法制备了WC/低铬铸铁复合铸渗层试样.通过金相观察、磨损实验研究了WC颗粒含量及WC包覆改性处理对渗层质量和渗层耐磨性的影响.结果表明:随着膏块中WC颗粒含量的增加,渗层中的硬质相也相应增加,在加入50%WC时渗层质量最好,磨损量最小,且经过包覆改性处理后的WC更容易形成优良渗层.     

稀土表面改性在改善高温抗氧化和耐蚀性方面的应用

稀土元素具有特殊的电子结构,对材料表面有着优异的改性潜力,在表面工程技术领域具有良好的应用前景.本文综述了在化学热处理、激光熔覆、离子注入、真空等离子体镀膜、热喷涂等技术中,稀土元素对工艺过程的影响和提高材料表面改性层高温抗氧化及耐腐蚀性能的效果.初步探讨了稀土元素在改性层中的作用机理.作者认为,稀土元素的微合金化作用,改变改性层中第二相或夹杂物的形态与性能,使改性层组织细化和结构因素,是稀土元素改善材料表面改性层高温抗氧化和耐腐蚀性能的主要原因.     

AZ91镁合金表面含Ti生物复合涂层结构及腐蚀学性能

采用冷喷涂法在AZ91合金表面预置纯Ti涂层,再采用微弧氧化对Ti涂层进行仿生生物改性.用SEM、XRD、EDS等方法分析涂层的组织结构,用动电位法测试涂层的腐蚀学性能.结果表明:冷喷涂预置Ti层厚度约100 μm,外表面形貌粗糙.微弧氧化处理后在Ti层表面产生微弧放电孔.生物改性层主要由Ti_2O_3组成,还含有少量钙、磷等物质.微弧氧化层有利于提高冷喷涂Ti层的生物学活性和致密性.含Ti复合涂层显著提高AZ91合金在模拟体液(SBF)中的自腐蚀电位(提高了约0.3 V),表明含Ti生物复合涂层具有良好的抗腐蚀性能.     

负离子粉表面改性方法与聚合物包覆性能研究

目的 比较三种不同改性方法对负离子粉表面改性的效果.方法 以KH-570为改性剂,分别采用球磨法、溶剂回流法和干研磨法对超细负离子粉进行表面有机化改性.将改性后的负离子粉分散到丙烯酸酯单体中,通过悬浮聚合在负离子粉表面生成聚合物包覆层,并制备成包含负离子粉的聚合物微球体.通过7230G分光光度计对比粉体在甲基丙烯酸甲酯单体中的悬浮性能.采用扫描电镜观察粉体的形貌特征以及聚合物包覆后粉体表面与聚合物的结合状况.分离出未被聚合物包覆的负离子粉,计算负离子粉的有效包覆率.采用COM-3010PRO负离子测试仪测试聚合物包覆前后负离子的释放性能.通过综合对比和分析,判断改性方法的优劣.结果 三种改性方法都可以实现对负离子粉表面的有机化改性.负离子粉表面有机化改性后,平均粒径减小,在甲基丙烯酸甲酯中分散悬浮稳定性明显增加.通过悬浮聚合可以得到聚合物包覆的负离子粉体微球,负离子粉在聚合物中分布均匀、结合牢固,聚合物有效包覆率最高可达79.2％.从改性后负离子粉的悬浮稳定性、聚合物包覆率、在聚合物中的分布状态以及负离子释放性能等方面,均体现出球磨法最优,溶剂回流法次之,干研磨法最差的规律.结论 球磨法是最佳的处理方法,负离子粉在聚合物中分布均匀,聚合物有效包覆率高,负离子释放量大.     

不锈钢堆焊层耐蚀性研究

本次研究采用三种不锈钢焊条A102、A132和A302在廉价的Q235低碳钢上进行堆焊.研究不同焊接工艺参数对母材熔合比的影响,以及熔合比与堆焊层耐蚀性的关系.通过对熔合比的测定,并对比发现,焊接电流越小熔合比越小.本次研究采还用了稀硫酸和稀盐酸作为腐蚀液,在扫描电镜下观察了腐蚀后的形貌.结果发现,A102焊条和A302焊条腐蚀后的形貌都出现了晶问腐蚀,其中A302不锈钢焊条堆焊层腐蚀形貌中还出现了部分点腐蚀.在A132焊条的腐蚀形貌中未发现晶问腐蚀,只发生了均匀腐蚀.还发现A302不锈钢焊条的堆焊层在稀盐酸和稀硫酸中的耐腐蚀性均好于A102和A132不锈钢焊条.     

A Study of the Corrosion Resistance of Pump–Compressor Pipes with a Diffusion Zinc Coating under the Complicated Conditions of Gas-Producing Wells

The results of corrosion tests of diffusion zinc coatings under the complicated corrosion and erosion conditions of gas-production wells are presented. The slowdown of the anodic process of the solution of a coating and its salt passivation in model solutions was shown by the electrochemical research. It was established that the corrosion rates of diffusion zinc-coated 36G2F steel samples were 4.1–6.1 times lower than those of samples without coating. The corrosion resistance and the operational reliability of pump–compressor pipes can be increased by using protective duplex system combining a diffuse zinc coating (protective layer) and an upper layer of a polymer coating (barrier layer).     

Influence of Treatment Sequence on Tribological Performance of Duplex Surface-Treated AISI 1045 Steel

The surface of AISI 1045 steel specimens was modified via two duplex surface treatments of(i) titanium diffusion coating followed by plasma nitriding(Ti–PN) and(ii) plasma nitriding followed by titanium diffusion coating(PN–Ti). A comparative study on the microstructure and wear properties of the fabricated TiN coatings was conducted. A scanning electron microscope equipped with energy-dispersive X-ray spectroscopy, X-ray diffractometer(XRD), and pin-on-disk wear test was utilized to evaluate the microstructures, phases, and wear properties of the coatings. XRD patterns of duplex-treated specimens illustrated that the modified layer consisted of nitride and carbo-nitride phases such as TiN and TiC_(0.7)N_(0.3). The results also showed that Ti–PN treatment led to a low friction coefficient and the lowest wear factors, as compared with the PN–Ti treatment. Oxidation and mild fatigue fracture wear were found to be the main wear mechanism of the Ti–PN coating. The wear mechanism in the PN–Ti specimen involved a higher oxidative wear regime followed by plastic deformation wear regimes.     

Zur Kinetik der Sauerstoffreduktion bei der Korrosion von Nickel in sauerstoffhaltiger Schwefelsäure

Kinetics of oxygen reduction during the corrosion of nickel in oxygen containing sulfuric acid The rate of oxygen reduction was determined for the corrosion of nickel in sulphuric acid containing oxygen. The rate depends upon the oxygen concentration and the acidity of the electrolyte. For a second order reaction with a preceding diffusion of oxygen and protons the values of the rate constant and the thickness of the diffusion layer were calculated. It could be shown that in In sulphuric acid the reduction rate is control led by the oxygen diffusion while in the weaker acids the rate controlling step is a proton transfer to the oxygen, adsorbed at the metal surface. Measurements of the dependance of the corrosion in In sulphuric and hydrochloride acid confirm these results.     

Mechanical Properties of TiN Coating on Nanocrystalline Surface Layer of 304 Stainless Steel

Surface nanocrystallization(SNC)can markedly improve surface mechanical properties of metallic materials and accelerate thermal diffusion of elemental atoms.In this work we study the effects of SNC on structure and mechanical properties of TiN coating on 304 stainless steel substrate.The steel was subjected to 15 min surface mechanical attrition treatment(SMAT)to obtain a nanocrystalline surface layer with thickness about 30μm.TiN coating was deposited on the surface nanocrystallized and the coarse-grained steel substrates by multi-arc ion plating.X-ray diffraction shows that TiN(111)orientation of the coating is much reduced due to SNC treatment.Mechanical tests show that the nanocrystalline surface layer has obviously increased surface hardness of the coating system;toughness and adhesion of the coating,impact resistance of the coating system are also improved.Advantages of SNC-hard coating processing over the conventional duplex treatment consisting of thermal diffusion process-hard coating are shortly discussed.     

Diffusion Barrier Coating System and Oxidation Behavior of Coated Alloys

1 Introduction Research into the formation of Re-based alloys is in progress in our laboratory to provide a diffusion barrier layer between heat-resistant alloys and Al reservoir layers, which assist in the formation and maintenance a protective Al2O3 scale for long periods. Coatings with a two-layered structure comprised of inner Re-based alloy layer and outer β-NiAl layer with or without Pt addition were successfully formed on various heat resistant alloys such as Ni-based singlecrystal superalloys, Ni-based heat resistant alloys, NiMo based alloy, Ni-Cr based alloy, and Fe-based alloys. The duplex layer coating proposed is generally termed a diffusion barrier coating system; DBC system.     

0Cr18Ni15Mo4不锈钢在稀硫酸介质中的表面钝化膜研究

采用AES和XPS表面分析技术,测定了OCr18Ni15Mo4奥氏体不锈钢在20％H_2SO_4和模拟湿法冶金铜电解液(20％H_2SO_4+35g/L Cu~(2+))中表面膜的合金元素分布、组态和结构。实验表明,表面钝化膜形成外层为氢氧化物和内层为氧化物的双层结构。在还原性稀硫酸中,钝化膜中形成以Mo(Ⅵ)和Cr~(3+)为主的含N氧化物、氢氧化物,当溶液中增加Cu~(2+)离子的去极化作用时,Mo元素的钝化作用受到抑制。     

高价铜、铁离子对钛材的缓蚀作用

研究了高价铜、铁离子对沸腾的酸性介质中钛管的缓蚀保护作用.结果表明,在40%Al2(SO4)3溶液中,当铜离子浓度达到0.01%(wt)时,可使钛的腐蚀率降到0.1mm/a以下,在pH=1的沸腾稀硫酸溶液中,当铜离子浓度达0.03%或铁离子浓度达0.01%时,可使钛管的腐蚀率降到0.02mm/a以下.     

纯镁表面等离子体电解渗硼与微弧氧化复合膜的制备及耐蚀性

目的 在纯镁表面制备新型复合膜,以提高其耐蚀性.方法 先在硼砂系电解液中对纯镁进行等离子体电解渗硼(PEB)处理,预制表面改性层,然后在硅酸盐系电解液中对其进行微弧氧化(MAO)处理,从而获得PEB+MAO新型复合膜.分别使用扫描电子显微镜(SEM)、能谱仪(EDS)和X射线衍射仪(XRD)分析膜层的微观结构、元素分布及物相组成,膜层的耐蚀性则通过动电位极化曲线和电化学阻抗谱(EIS)来表征.结果 纯镁的等离子体电解渗硼过程经历了电离、置换、吸附和扩散四个阶段,获得的PEB表面改性层由氧化层和扩散层组成.在PEB+MAO复合膜的生长过程中,膜层在其厚度方向存在重叠的现象,而不是逐层的简单堆积.等离子体电解渗透时,硼元素渗入后所形成的渗层区域降低了纯镁基体表面的化学活性,改善了其微观组织结构,进而使PEB+MAO复合膜的腐蚀电流密度较基体、单一PEB改性层和单一微弧氧化膜层分别降低了3、2、1个数量级.同时,EIS研究也表明,PEB+MAO复合膜可以提供相对较长时间的抗蚀保护.另外,分析了PEB表面改性层的生成机理以及PEB+MAO复合膜的形成过程,并建立了物理模型.结论 PEB预处理会显著影响PEB+MAO复合膜的厚度、致密性及成分,继而明显提高纯镁的耐蚀性.该新型的复合膜制备方法有望进一步推广到镁合金上,以提高其耐蚀性和承载能力.     

包埋渗结合激光熔覆制备复合涂层的高温抗氧化性

为了提高铌合金的抗氧化性能,采用铝硅共渗的方法在铌合金表面制备Al-Si涂层,结合激光熔覆技术于渗层上熔覆MOSi2涂层。探讨了Al-Si渗层的生长机制,研究了铌合金表面Al-Si渗层及MoSi2/Al-Si涂层的抗高温氧化性能。结果表明:Al-Si渗层的形成过程是源于Al、Si元素的先后沉积,优先形成了Al3Nb相。渗层厚度x与保温时间f遵循关系式:x=At1/2+7.4(1000℃:A=11.6,1050℃:A=16.2)。激光熔覆制备的MoSi2/Al-Si涂层均匀连续致密,与基体结合紧密,无裂纹孔洞等缺陷。主要相结构为MoSi2、Al3Nb、NbSi2、Nb5Si3和Mo(Si,Al)2。经1200℃氧化后,Al-Si渗层及MoSi2/Al-Si涂层都形成大量的SiO2保护膜,阻止了氧原子的进一步扩散。与Al-Si渗层相比,MoSi2层表面形成的连续致密混合氧化物有效避免了Al-Si渗层的快速消耗,MoSi2/Al-Si涂层的高温氧化优于Al-Si渗层。