正交试验优化电沉积 Ni-Cr 泡沫合金工艺

目的获得电沉积Ni-Cr泡沫合金的最佳工艺参数。方法采用正交实验法研究镀液成分等工艺参数对镀层沉积速率、厚度以及合金中Cr含量的影响,并利用扫描电子显微镜等测试手段对镀层横截面厚度等镀层指标进行了考察。结果阴极电流密度为28 A/dm2,镀液pH值为2.0,镀液温度为25℃,CrCl3·6H2O的质量浓度为125 g/L,配位剂与Cr3+摩尔比为1.8时,电沉积60 min能够获得表面光亮平整的Ni-Cr合金镀层,镀层厚度为24.09μm,沉积速率为0.4198 mg/(cm2·min),镀层中Cr的质量分数为14.76%。结论镀液温度在25~40℃范围内,对Ni-Cr合金镀层厚度、沉积速率的影响最大;镀液中CrC13·6H2O浓度、配位剂与Cr3+的摩尔比两个因素,对合金镀层中Cr含量的影响较大。     

碳纳米管／锡基轴瓦合金复合减摩镀层的制备

采用复合电沉积方法在铜基轴瓦合金的表面制备碳纳米管/锡基轴瓦合金复合减摩镀层,研究了电沉积工艺参数对碳纳米管/锡基复合镀层的组织与性能的影响.结果表明,当阴极电流密度为1.5A/dm2,镀液中碳纳米管的质量浓度为2 g/L、镀液的pH值为1时,镀层生长良好,碳纳米管分布均匀.     

Preparation of Ni/CrAI Coatings on T91 Steel by Composite Electrodeposition

采用复合电沉积法在T91钢表面制备Ni/CrAl镀层,研究了CrAl微粒在镀层中的含量与搅拌强度、镀液pH值、电流密度及温度的关系,确定最佳工艺参数为:电流密度2.5～4.5 A/dm2,pH值4～4.5,温度30℃.采用该工艺制备了较高CrAl含量的复合镀层,并对工艺参数影响复合电沉积的机理进行了简单探讨.     

电沉积NiP非晶态合金的影响因素

本文研究了镀液浓度、温度、阴极电流密度、沉积层厚度以及不同基体材料等因素对沉积Ni-P非品态合金的影响.用X射线衍射仪,透射电子显微镜,电子探针显微分析仪等测定所得沉积合金的结构与组份.观察到在一定镀液浓度范围内,镀液的温度、电沉积时阴极电流密度,几种不同基体材料以及沉积层的厚度对是否获得非晶态合金影响均不明显,影响的关键因素是镀液中的Ni与P的比值.     

ZnSe薄膜电沉积工艺条件的研究

采用电沉积方法制备了ZnSe薄膜,研究了电沉积工艺参数,包括镀液的主盐离子浓度、配合剂浓度、pH值及电流密度等对膜层的影响.通过正交试验对上述各参数进行优化,以寻求最佳的工艺条件,得到最佳制备条件为:电流密度6.0mA/cm2,柠檬酸钠14.71g,pH值3.5,Zn2 /SeO2-3浓度比200:1,温度65℃,时间8min.在此条件下制备了薄膜样品,并用扫描电镜、EDAX能谱仪对镀层进行了表征,其结构均匀致密,Zn/Se化学计量比为1/1.01.     

AZ91镁合金表面制备Ni-SiO2纳米复合电镀层的工艺研究

采用复合电沉积技术在AZ91镁合金表面制备Ni-SiO2纳米复合镀层,并研究各工艺参数对镀层的影响,从而得出最佳工艺.研究结果表明:在镀液中纳米SiO2的添加量为20 g/L,阴极电流密度为1.0 A/dm2,镀液温度为50℃,活性剂A的添加量为1.0 g/L,pH为5～6的条件下,经过20～30 min电沉积,可获得均匀、平滑的镀层,镀层的显微硬度与耐蚀性最佳.     

T91钢表面复合电沉积Ni/CrAl镀层的工艺研究

采用复合电沉积法在T91钢表面制备Ni/CrAl镀层,研究了CrAl微粒在镀层中的含量与搅拌强度、镀液pH值、电流密度及温度的关系,确定最佳工艺参数为:电流密度2.5～4.5A/dm2,pH值4～4.5,温度30℃。采用该工艺制备了较高CrAl含量的复合镀层,并对工艺参数影响复合电沉积的机理进行了简单探讨。     

电沉积工艺对镀锌层的表面形态及电化学性能的影响

采用电沉积技术制备几种电沉积式锌电极,考察镀液中KOH浓度和沉积电流密度对所制得镀锌层的微观形貌与性能的影响规律.结果表明镀锌层的枝晶随着KOH浓度(250～400 g/L)的增加而变得粗大,且其析氢量、腐蚀电位和腐蚀电流密度均呈现先减小而后增加的趋势;随着电流密度(25～100 mA/cm2)的增长,镀锌层由块状结晶向枝晶转变,相应地电极反应活性随之增大,而耐蚀性则随之变差,并发现沉积电流密度为75 mA/cm2时,锌电极的综合性能最好,以200 mA/g充放电循环10周次,其放电容量仍可达504 mA-h/g.解释了主要工艺参数对结晶形态及电极性能影响的原因,并说明适当的KOH浓度和沉积电流密度有利于提高电极的综合性能.     

Cu-W复合电沉积工艺研究

电接触材料要求具有很好的抗电弧烧蚀和抗熔焊性能,但纯铜很难达到该种要求.利用复合电沉积方法,在纯铜表面形成Cu-W复合镀层,使其满足电触头材料的使用性能.重点研究了镀液中W的质量浓度、电流密度、搅拌强度和温度工艺参数对Cu-W电接触材料复合镀层中W微粒沉积量的影响,并且通过正交试验确定了复合电沉积的最优工艺:W的质量浓度为35g/L、电流密度为4A/dm2、搅拌强度为600r/mjn、温度为50℃.     

基于TEA和EDTA·2Na双络合体系的酸性镀铜工艺及镀层特性

锂离子电池用负极集流体铜箔材料目前主要采用电沉积法制备。为制备良好的电解铜箔,采用不同电镀工艺参数,在基于三乙醇胺(TEA)和乙二胺四乙酸二钠(EDTA.2Na)双络合体系的CuSO4/H2SO4溶液中进行镀铜工艺研究。通过线性扫描、循环伏安、SEM和XRD手段对镀液性质、镀层微观形貌和结构进行测定和表征,并进行镀层质量重复性实验。结果表明:选择含P 0.1%的磷铜作为阳极,采取机械搅拌镀液的方式,在CuSO4.5H2O为300 g/L、H2SO4为90 g/L、Cl-为40~80 mg/L、TEA为3.5 g/L和EDTA.2Na为5 g/L中适量添加剂P的镀液中,以电流密度为490 mA/cm2,镀液温度为40~60℃,施镀5~10 min能得到良好镀层;添加剂明显降低循环伏安阴极峰电流,Cu2+的还原速度减慢;添加剂提高镀层表面的结晶细化程度,使晶体颗粒变小,致密性提高,镀层质量变好,整平作用明显,Cu镀层呈现(111)晶面择优取向;镀速可达19.4 mg/min,镀层质量有很好的重现性。     

RHEOLOGY FEATURE OF SIMPLE METAL MELT

The rheology feature of Sb, Bi melt and alloys was studied using coaxial cylinder high-temperature viscometer. The results showed that the curve of torsion-rotational speed for Sb melt presents a linear relation in all measured temperature ranges, whereas for the Bi melt, the curve presents obvious non-Newtonian feature within the low temperature range and at relative high shear stress. The rheology feature of Sb80Bi20 and Sb20Bi80 alloy melts was well correlated with that of Sb and Bi, respectively. It is considered that the rheology behavior of Sb melt plays a crucial role in Sb80Bi20 alloy and that of Bi melt plays a crucial role in Sb20Bi80 alloy.     

Microstructures and Mechanical Properties of a Newly Developed Austenitic Heat Resistant Steel

The effect of heat treatment on the microstructures and mechanical properties of a newly developed austenitic heat resistant steel(named as T8 alloy) for ultra-supercritical applications have been studied. Results show that the main phases in the alloy after solution treatment are γ and primary MX. Subsequent aging treatment causes the precipitation of M_(23)C_6 carbides along the grain boundaries and a small number of nanoscale MX inside the grains. In addition, with increasing the aging temperature and time, the morphology of M_(23)C_6 carbides changes from semi-continuous chain to continuous network.Compared with a commercial HR3C alloy, T8 alloy has comparable tensile strength, but higher stress rupture strength. The dominant cracking mechanism of the alloy during tensile test at room temperature is transgranular, while at high temperature, intergranular cracking becomes the main cracking mode, which may be caused by the precipitation of continuous M_(23)C_6 carbides along the grain boundaries. Typical intergranular cracking is the dominant cracking mode of the alloy at all stress rupture tests.     

The 15th Global Foundry Sourcing Conference 2014held in Qingdao China

Organized by Suppliers China Co., Ltd and co-organized by the National Technical Committee 54 on Foundry of Standardization Administration of China, the 15th Global Foundry Sourcing Conference 2014 （hereinafter referred to as FSC 2014） was successfully held on Sep. 23rd in Grand Regency Hotel, Qingdao. More than 500 delegates from home and abroad attended this conference, including over 130 purchasers from 20 countries and 380 domestic and foreign suppliers.     

LASER CLADDED TiCN COATINGS ON THE SURFACE OF TITANIUM

Laser cladded coatings of TiCN were produced on the surface of titanium. To obtain the optimal techniques, several conditions were tested by varying the laser scanning rate. The choice of shielding gas was also studied. The cladded coatings were then evaluated from the surface mechanics point of view based on their microhardness. The microstructure of some interesting samples was investigated by optical micrographs (OM). The results showed that under the condition of fixed pulse frequency and pulse width, the laser scanning rate and the shielding gas are the main factors influencing the components of coatings. TiCN coatings were decompounded and oxidized during the cladding process in the condition of no shielding gas of N2. X-ray diffraction results indicated that the composite coatings composed of TiCN, TiC, Ti2N, and TiO2 were produced using appropriate techniques. The results indicated that the best condition in terms of the surface microhardness is obtained when the scanning rate is 1.5mm / s, the pulse frequency is 15Hz, the pulse width is 3.0ms, and N2 is chosen as the shielding gas. The microhardness of the composite coatings is about 1331kg · mm - 2, which is about 4 times that of the substrate. The optical micrographs indicated that the cladding zone is made up of TiCN, TiO2, and some interdendritic Ti, but the diffusion zone mainly consists of the dendrites phase, and the cladded depth is about 80m, which is more than 2 times that of the laser nitrided sample. There were no microcracks or air bubbles in the cladded sample, which was cladded using the above optimal techniques.     

Microstructure and Mechanical Properties of X80 Pipeline Steel Joints by Friction Stir Welding Under Various Cooling Conditions

X80 pipeline steel plates were friction stir welded(FSW) under air, water, liquid CO_2 + water, and liquid CO_2 cooling conditions, producing defect-free welds. The microstructural evolution and mechanical properties of these FSW joints were studied. Coarse granular bainite was observed in the nugget zone(NZ) under air cooling, and lath bainite and lath martensite increased signifi cantly as the cooling medium temperature reduced. In particular, under the liquid CO_2 cooling condition, a dual phase structure of lath martensite and fi ne ferrite appeared in the NZ. Compared to the case under air cooling, a strong shear texture was identifi ed in the NZs under other rapid cooling conditions, because the partial deformation at elevated temperature was retained through higher cooling rates. Under liquid CO_2 cooling, the highest transverse tensile strength and elongation of the joint reached 92% and 82% of those of the basal metal(BM), respectively, due to the weak tempering softening. A maximum impact energy of up to 93% of that of the BM was obtained in the NZ under liquid CO_2 cooling, which was attributed to the operation of the dual phase of lath martensite and fi ne ferrite.     

INDUSTRY NEWS

China Securities News reported on March 21, 2014： Guangdong Hongtu Wuhan Die Casting Co., Ltd. （Wuhan Hongtu）, a wholly owned subsidiary of Guangdong Hongtu Technology （Holdings） Co., Ltd., held a groundbreaking ceremony recently. With the registered capital of 50 million Yuan, Wuhan Hongtu has a total land area of 100,000 square meters and a plant construction area of 72,000 square meters. It is expected to have a production capacity of about 30,000 tonnes of aluminum castings annually after it is put into production.     

GROWTH MORPHOLOGIES OF A BINARY ALLOY WITH LOW ANISOTROPY IN DIRECTIONAL SOLIDIFICATION

Two new classes of growth morphologies, called doublons and seaweed, were simulated using a phase-field method. The evolution of doublon and seaweed morphologies was obtained in directional solidification. The influence of orientation and velocity on the growth morphology was investigated. It was indicated that doublons preferred growing with its crystallographic axis aligned with the heat flow direction. Seaweed, on the other hand, could be obtained by tilting the crystalline axis to 45°. Stable doublons could only exist in a range of velocity regime. Beyond this regime the patterns formed would be unstable. The simulation results agreed with the reported experimental results qualitatively.     

STUDY ON PROPERTIES OF PULSE ELECTRODEPOSITED RE-Ni-W-P-SiC COMPOSITE COATINGS

The effects of pulse frequency f and duty cycle r on the deposition rate, composition, morphology, and hardness of pulse electrodeposited RE （rare earth）-Ni-W-P-SiC composite coatings have been studied. The results indicate that pulse current can improve the deposition rate of RE-Ni-W-P-SiC composite coatings; W, P, and SiC contents in the coating decrease with the increase of pulse frequency and reach the lowest value at f = 33Hz, whereas the RE content in the composite coatings increases with the increase of pulse frequency. SiC content decreases with the increase of duty cycle, W content reaches the lowest value, and P content reaches the highest value at r = 0.4; pulse current and RE can lead to smaller size of the crystalline grains; however, the effects of different pulse frequency and duty cycle on the morphologies of RE-Ni-W-P-SiC composite coatings are not obvious. The hardness of RE-Ni-W-P-SiC composite coatings is the highest when the duty cycle is at 0.6 and 0.8 and pulse frequency is at 50Hz. At the same pulse frequency, the hardness of RE-Ni-W-P-SiC composite coatings at r= 0.8 is higher than that at r= 0.6.     

RELATIONSHIP BETWEEN J-INTEGRAL AND FRACTURE SURFACE AVERAGE PROFILE

To investigate the causes that led to the formation of cracks in materials, a novel method that only considered the fracture surfaces for determining the fracture toughness parameters of J-integral for plain strain was proposed The principle of the fracture-surface topography analysis （FRASTA） was used. In FRASTA, the fracture surfaces were scanned by laser microscope and the elevation data was recorded for analysis. The relationship between J-integral and fracture surface average profile for plain strain was deduced. It was also verified that the J-integral determined by the novel method and by the compliance method matches each other well.