Wear Evaluation of Copper-Nickel-Aluminum Alloys under Extreme Conditions

Cu-Ni-Al alloys at different concentrations were obtained using a high frequency induction melting unit, keeping a balance in the nominal compositions. Light alloys are important to be used in industrial applications. Aluminum additions result in a positive hardness increment of the ternary alloys in comparison with the binary Cu-Ni alloys. Generalized wear mechanisms of the alloys with low aluminum content are basically type abrasive, while samples with 5 and 10 at.% Al present an oxidative-adhesive wear mechanism. Wear results have indicated that aluminum addition affects positively the wear resistance, mainly in samples with high aluminum content product of the creation during the test of different oxides corresponding to the elements present in the alloys.

Microstructural evolution and mechanical properties of friction stir-welded C71000 copper–nickel alloy and 304 austenitic stainless steel

Dissimilar joints comprised of copper–nickel and steel alloys are a challenge for manufacturers in modern industries, as these metals are not thermomechanically or chemically well matched. The present study investigated the effects of tool rotational speed and linear speed on the microstructure and mechanical properties of friction stir-welded C71000 copper–nickel and 340 stainless steel alloys using a tungsten carbide tool with a cylindrical pin. The results indicated that a rotational-to-linear speed ratio of 12.5 r/mm did not cause any macro defects, whereas some tunneling defects and longitudinal cracks were found at other ratios that were lower and higher. Furthermore, chromium carbide was formed on the grain boundaries of the 304 stainless steel near the shoulder zone and inside the joint zone, directing carbon and chromium penetration toward the grain boundaries. Tensile strength and elongation percentages were 84% and 65% of the corresponding values in the copper–nickel base metal, respectively.

Inhibition effects of PMA/SbBr_3 complex inhibitor on copper and copper-nickel alloy in LiBr solutions

The effects of PMA/SbBr3 inhibitor on copper and copper-nickel alloy in 55%LiBr solution were investigated by chemical immersion and electrochemical measurements. The results indicate that in boiling 55%LiBr solution containing PMA/SbBr3 inhibitor, corrosion rates of copper and copper-nickel alloy are 67.48μm/a and 38.14μm/a, respectively. Since both anodic and cathodic electrochemical reactions can be inhibited, PMA/SbBr3 belongs to complex inhibitor. PMA has the effect of inhibiting hydrogen evolution and [PMo<sup>12 O<sup>40 ]3- , the anion of PMA, has a strong oxidizing effect. Sb3+ also shows an oxidizing effect. It may exist in LiBr solutions stably with PMA. Because of the synergistic effect of PMA and Sb3+ , a protective film, comprising CuO, Cu2O and Sb, formed on copper and copper-nickel alloy surface may prevent Br-from diffusing to the surface of metals. As a result, the anticorrosion performance of copper and copper-nickel alloy may be improved.

Liquid-solid interface control of BFe10-1-1 cupronickel alloy tubes during HCCM horizontal continuous casting and its effect on the microstructure and properties

Based on horizontal continuous casting with a heating-cooling combined mold （HCCM） technology, this article investigated the effects of processing parameters on the liquid-solid interface （LSI） position and the influence of LSI position on the surface quality, microstructure, texture, and mechanical properties of a BFe10-1-1 tube （φ50 mm × 5 mm）. HCCM efficiently improves the temperature gradient in front of the LSI. Through controlling the LSI position, the radial columnar-grained microstructure that is commonly generated by cooling mold casting can be eliminated, and the axial columnar-grained microstructure can be obtained. Under the condition of 1250℃ melting and holding temperature, 1200-1250℃ mold heating temperature, 50-80 mm/min mean drawing speed, and 500-700 L/h cooling water flow rate, the LSI position is located at the middle of the transition zone or near the entrance of the cooling section, and the as-cast tube not only has a strong axial columnar-grained microstructure （{hkl}〈621〉, {hkl}〈221〉） due to strong axial heating conduction during solidification but also has smooth internal and external surfaces without cracks, scratches, and other macroscopic defects due to short solidified shell length and short contact length between the tube and the mold at high temperature. The elongation and tensile strength of the tube are 46.0%-47.2% and 210-221 MPa, respectively, which can be directly used for the subsequent cold-large-strain processing.

Effect of additives on anode passivation in direct electrolysis process of copper–nickel based alloy scraps

Effects of nickel component,thiourea,glue and chloride ions and their interactions on the passivation of copper–nickel based alloy scrap anodes were investigated by combining conventional electrochemical techniques.Results obtained from chronopotentiometry and linear voltammetry curves showed that the Ni component made electrochemical stability of the anode strong and difficult to be corroded,caused by the adsorption of generated Cu2O,NiO or copper powder to the anode surface.The Ni2+reducing Cu2+to Cu+or copper powder aggravated the anode passivation.In a certain range of the glue concentration≤8×10–6 or thiourea concentration≤4×10–6,the increase of glue or thiourea concentration increases the anode passivation time.Over this range,glue and thiourea played an adverse effect.The increase of chloride ions concentration led to the increase in passivation time.

Effects of Fe content on the microstructure and properties of CuN i10FeM n1 alloy tubes fabricated by HCCM horizontal continuous casting

Heating-cooling combined mold（HCCM） horizontal continuous casting technology developed by our research group was used to produce high axial columnar-grained CuN i10 FeM n1 alloy tubes with different Fe contents. The effects of Fe content（1.08wt%–2.01wt%） on the microstructure, segregation, and flushing corrosion resistance in simulated flowing seawater as well as the mechanical properties of the alloy tubes were investigated. The results show that when the Fe content is increased from 1.08wt% to 2.01wt%, the segregation degree of Ni and Fe elements increases, and the segregation coefficient of Ni and Fe elements falls from 0.92 to 0.70 and from 0.92 to 0.63, respectively. With increasing Fe content, the corrosion rate of the alloy decreases initially and then increases. When the Fe content is 1.83wt%, the corrosion rate approaches the minimum and dense, less-defect corrosion films, which contain rich Ni and Fe elements, form on the surface of the alloy; these films effectively protect the α-matrix and reduce the corrosion rate. When the Fe content is increased from 1.08wt% to 2.01wt%, the tensile strength of the alloy tube increases from 204 MPa to 236 MPa, while the elongation to failure changes slightly about 46%, indicating the excellent workability of the CuNi10FeMn1 alloy tubes.

Laser cladding of Ni-based alloy on copper substrate

The laser cladding of Ni1015 alloy on Cu substrate was prepared by a high power continuous wave CO2 laser. Its microstructure was analyzed by optical microscope （OM）, scanning electron microscope （SEM）, and X-Ray diffraction （XRD）. The average microhardness of the cladding coating was Hv 280, which was almost three times of that of the Cu substrate （Hv 85）. OM and SEM observations showed that the obtained coating had a smooth and uniform surface, as well as a metallurgical combination with the Cu substrate without cracks and pores at the interface. With the addition of copper into the nickel-based alloy, the differences of thermal expansion coefficient and melting point between the interlayer and cladding were reduced, which resulted in low stresses during rapid cooling. Moreover, large amount of （Cu, Ni） solid solution formed a metallurgical bonding between the cladding coating and the substrate, which also relaxed the stresses, leading to the reduction of interfacial cracks and pores after laser cladding.

Air oxidation of Cu-50Ni and Cu-70Ni alloys at 800℃

The air oxidation of Cu Ni alloys with 50% and 70% nickel (mole fraction) at 800?℃ was studied. The kinetic curves for the oxidation of the two alloys are complex and deviate from the parabolic rate law. Typical double layered scales are produced, which consist of a CuO outer layer and an inner layer containing a mixture of Cu 2O and NiO with many pores. Cu 50Ni presents a small degree of internal oxidation of nickel, which is observed in many binary double phase systems, but is quite rare in single phase systems.

Kinetics of discontinuous precipitation in Cu–20Ni–20Mn alloy

The morphology and growth kinetics of discontinuous precipitation （DP） in a Cu-20Ni-20Mn alloy were investigated in the tem- perature range of523-573 K by optical microscopy, scanning electron microscopy, and transmission electron microscopy. A lamellar mixed structure consisting of alternating larnellae of a matrix and NiMn phase was observed in DP colonies. The volume fraction of regions formed by a DP reaction was determined by quantitative metallographic measurements. The kinetics of DP was evaluated on the basis of the John- son-MehI-Avrami Kohnogorov equation, which resulted in a time exponent of approximately 1.5. We confirmed that the nucleation of the discontinuous precipitate was confined to grain edges or boundaries at an early stage of the reaction. The activation energy of DP process was determined to be approximately （72.7 ± 7.2） kJ/mol based on the Arrhenius equation; this result suggests that DP is controlled by gn-ain boundary diffusion. The hardness values exhibited good correlation with the volume fraction of DP; this correlation was attributed to the plvsence of the ordered N iMn phase.

Electrolytic production of Cu-Ni alloys in CaCl_2-Cu_2S-NiS molten salt

An alternative metal/alloy production method,known as direct electrochemical reduction(DER),was introduced for the fabrication of CuNi alloys from mixed sulfides(Cu2S,NiS)under both galvanostatic and potentiostatic conditions.The influences of the process parameters(e.g.,cell voltage and current)on the compositions of the reduced compounds were investigated to yield industrially desirable alloys,namely,CuNi10,CuNi20,and CuNi30.The electrochemical behaviors of Cu2S and NiS in CaCl2 melt were examined at a temperature of 1200°C via cyclic voltammetry(CV).Based on the CV results,the cathodic reduction of Cu2S occurred in one step and cathodic reductions of NiS occurred in two steps,i.e.,Cu2S?Cu for copper reduction and NiS?Ni3S2?Ni for nickel reduction.Galvanostatic studies revealed that it was possible to fabricate high-purity CuNi10 alloys containing a maximum sulfur content of 320×10-6 via electrolysis at 10 A for 15 min.Scanning electron microscopy along with energy-dispersive X-ray spectrometry and optical emission spectroscopy(OES)examinations showed that it was possible to fabricate CuNi alloys of preferred compositions and with low levels of impurities,i.e.,less than 60×10-6 sulfur,via DER at 2.5 V for 15 min.

Effect of compression direction on the dynamic recrystallization behavior of continuous columnar-grained CuNi10Fe1Mn alloy

The dynamic recrystallization（DRX） behavior of continuous columnar-grained（CCG） Cu Ni10Fe1 Mn alloy was investigated by hot compression along the solidification direction（SD） and perpendicular to the solidification direction（PD）. Specimens were compressed to a true strain of 0.8 at temperatures ranging from 25°C to 900°C and strain rates ranging from 0.01 to 10 s-1. The results indicate that DRX nucleation at grain boundaries（GBs） and DRX nucleation at slip bands（SBs） are the two main nucleation modes. For SD specimens, C-shaped bending and zig-zagging of the GBs occurred during hot compression, which made DRX nucleation at the GBs easier than that at the SBs. When ln Z ≤ 37.4（Z is the Zener–Hollomon parameter）, DRX can occur in SD specimens with a critical temperature for the DRX onset of;50°C and a thermal activated energy（Q） of 313.5 k J·mol-1. In contrast, in PD specimens, the GBs remained straight, and DRX nucleation occurred preferentially at the SBs. For PD specimens, the critical temperature is about 700°C, Q is 351.7 k J·mol-1, and the occurrence condition of DRX is ln Z ≤ 40.1. The zig-zagging of GB morphology can significantly reduce the nucleation energy at the GBs; as a result, DRX nucleation occurs more easily in SD specimens than in PD specimens.

Effect of Solution Heat Treatment in α+β Phase Region on Shape Memory Characteristics of Cu-Al-Ni-Mn-Ti Alloys

The effect of aluminium content and solution heat treatment in α+β phase region on the shape memory characteristics and mechanical properties of cold wrought Cu-Al-Ni-Mn-Ti alloy are studied in this paper. Results indicate that the transformation temperature (Tt) of Cu-Al-Ni-Mn-Ti alloy reduces obviously with the increase of the amount of α-phase. During aging at 623 K, Tt increases at first up to a peak value, then decreases with prolongation of aging time. Life time of heat resistance of the alloy at high temperatures is improved with increase of the amount of α-phase, this life time becomes poor with Bainite precipitation. When the amount of α-phase is less than 5%, the ratio of shape recovery brought about by the solution heat treatment in α+β phase region is almost not effected. However, plasticity of the alloy increases obviously as aluminium content decreases. We believe that improving cold workability of Cu-Al-Ni-Mn-Ti alloy and keeping good heat resistant property and shape memory effects are possible by means of reducing the content of aluminium and solulion heat treatment in α+β phase region.

Effect of grain size on high-temperature oxidation behavior of Cu-80Ni alloy

The thermogravimetric analysis of binary Cu 80Ni alloys prepared respectively by conventional casting(CA) and mechanical alloying(MA) techniques and presenting widely different grain sizes was performed at 800 ℃ in air in order to study the effect of grain size change on the oxidation behavior of a solid solution alloy. The results show that the kinetic curves for the oxidation of the two alloys are complex and deviate from the parabolic rate law and usually are not composed of a single stage. Mixed scales were produced on the CACu 80Ni alloy surface, which consists of a mixture of copper and nickel oxides. However, oxide scale for MACu 80Ni alloy is mainly composed of a thick compact and continuous inner layer of nickel oxide. The reduction in the alloy grain size speeds up the diffusion of the more reactive component nickel from the alloy to alloy/oxide scale interface and completes the transition from a mixed scale to continuous scale of nickel oxide.

海洋平台海水系统新材料适用性研究

海洋平台利用周围取之不尽的海水作为平台的工艺处理介质已成常规做法。因为海水利用的普通性、经济性以及重要性,对于海水系统选材通常涉及到的使用寿命、制造成本、耐腐蚀性能等多个方面研究值得关注。对常用的几种海水管道材料进行了系统的比较和评价,并介绍了一些新型材料应用前景。在综合考虑各种材料的优劣后,提出了一种最适合海洋平台海水系统的选材方案,并阐述了其理由和依据。旨在为海洋平台海水系统设计和施工提供借鉴。

海洋工程用铜镍合金的腐蚀与防护研究进展

铜镍合金因具有良好的耐海水腐蚀性能、高的传热系数、优良的抗微生物附着性能和冷热加工性能,被广泛应用于船舶海水冷凝系统、滨海电厂的热交换器等海洋工程领域。本文围绕海洋工程用铜镍合金的腐蚀行为,首先概述了铜镍合金铸态、变形态及热处理的组织结构特点,接着归纳分析了合金元素、温度、pH值和硫离子对铜镍合金耐蚀性的影响,重点综述了合金化法、牺牲阳极法、缓蚀剂法、防腐涂料法和膜技术等铜镍合金耐蚀性的提升方法,最后展望了海洋工程用铜镍合金的发展趋势。

十六烷基三甲基溴化铵对电镀铜-镍合金耐蚀性的影响

[目的]研究Cu-Ni合金电镀液中添加不同质量浓度的十六烷基三甲基溴化铵(CTAB)对Cu-Ni合金镀层耐蚀性的影响。[方法]通过浸泡腐蚀试验、塔菲尔极化曲线测试和电化学阻抗谱(EIS)考察了Cu-Ni合金镀层的耐蚀性。通过扫描电镜(SEM)、能谱仪(EDS)和X射线衍射仪(XRD)分析了Cu-Ni合金镀层的表面形貌、成分和晶相结构。采用傅里叶变换红外光谱仪(FTIR)分析了CTAB在Cu-Ni合金镀层中的夹杂情况,并通过接触角测量研究了Cu-Ni合金镀层的疏水性。此外,根据阴极极化曲线测试结果,研究了CTAB质量浓度对Cu、Ni及Cu-Ni合金电沉积行为的影响。[结果]随着镀液中CTAB质量浓度增大,Cu-Ni合金镀层的耐蚀性先变好后变差。CTAB质量浓度为80mg/L时所得Cu-Ni合金镀层表面呈花椰菜状的空间立体形貌,镀层中Cu、Ni质量分数分别为50.25%和40.86%,对腐蚀液的接触角达到129.49°,耐蚀性最佳。[结论]镀液中添加适量CTAB能够显著提高Cu-Ni合金镀层的耐蚀性。

金川铜镍硫化矿选矿降镁药剂研究进展

金川铜镍硫化矿作为超大型铜镍矿床,资源丰富,除主要元素镍外,还有铜、钴及铂族金属元素伴生。随着常年开采,金川铜镍硫化矿矿石贫、细、杂的情况也愈发明显。由于采用选冶联合的铜镍分离方式,在以易浮的蛇纹石为主要含硅酸盐脉石情况下,随着原矿的不断贫化,仍需要保证MgO的合格,这为选矿工作带来非常大的难度和挑战。金川铜镍硫化矿浮选降镁问题作为世界性难题,由此得到广泛关注,针对其降镁问题的选矿药剂也在不断开发中。但在实际生产过程中,往往需要结合现场生产情况和实际生产成本,有些药剂对企业效益提升往往不大。总结阐述了金川公司往年针对铜镍硫化矿降镁药剂的研究进展,以及其他含氧化镁矿物降镁的选矿药剂的发展情况,望能给广大选矿工作者在铜镍硫化矿降镁方面提供技术参考。

压延铜箔的无氰电镀镍铜黑化处理工艺

为了研究出相较于电镀纯镍黑化工艺成本更低的电镀镍铜黑化工艺,以NiSO_(4)·6H_(2)O、CuSO_(4)·5H_(2)O、H_(3)BO_(3)、(NH_(4))_(2)S_(2)O_(8)和C_(6)H_(15)NO_(3)为镀液基本成分,通过加入添加剂,使金属在铜箔表面沉积形成光陷阱结构,从而实现电镀镍铜使铜箔黑化的目的。研究了镀液成分及工艺参数对黑化箔镀层亮度的影响,对黑化箔镀层的成分进行了测试,并对黑化箔镀层结构进行了观察分析。研究结果表明:电镀镍铜的黑化箔镀层中Cu代替Ni形成镀层,黑化箔镀层成分为NiCu;通过加入添加剂可以使电镀时使用的电流密度降低,达到了降低成本的目的。

电感耦合等离子体发射光谱法测定钼铬合金中9种元素

介绍了用硝酸钾、氢氧化钠熔融钼铬合金样品,硫酸酸化,在钼铬基体中加入待测元素的标准溶液绘制工作曲线,将试液雾化后导入ICP,同时测定铝、钴、铜、铁、锰、镍、硅、钛、钨元素发射光强度,计算各元素的百分含量。

镍铜合金类零件渗透检测方法分析

镍铜合金以其耐高温、耐腐蚀、耐磨损、易加工等优势在设备零件制造领域得到广泛应用。为保证镍铜合金类零件应用的可靠性、安全性、持续性,需要做好其质量与性能检测,以及时发现缺陷零件,做好相关处理工作。渗透检测是镍铜合金类零件质量检测重要手段,但在实践中经常发生晶间裂纹漏检问题,降低渗透检测结果的准确性、可靠性。现从理论与实践两个角度探寻镍铜合金类零件渗透检测问题,以获取较好镍铜合金类零件渗透检测方法。理论角度简要对镍铜合金类零件质量检测、渗透检测原理与方法进行介绍;实践角度主要对镍铜合金类零件渗透检测结果影响因素、改进方法及其应用效果进行探究。结果表明,镍铜合金类零件表面状态对渗透检测结果影响较大,利用三氯化铁溶液对镍铜合金类零件进行预处理,能够在一定程度上降低表面状态影响,减少晶间裂纹漏检率,提高渗透检测结果的准确性、可靠性。