三价铬水溶液电镀非晶态铬工艺

报导了一种Ｃｒ３ ＋ 水溶液中电镀非晶态铬新工艺。采用由适当的络合剂、稳定剂、添加剂以及Ｃｒ３ ＋ 盐组成的电镀液, 于室温下电沉积出厚度达１１ μｍ 、外观接近镜面的非晶态铬镀层。实验发现, 蓝膜的生成是光亮非晶态Ｃｒ 层得以电沉积出来的首要条件。采用Ｘ 射线衍射和扫描电子显微镜等方法对铬镀层的结构进行了分析。结果表明, 铬镀层的Ｘ 射线衍射图中只有非晶态铬的宽化峰; 扫描电子显微镜结果显示所得Ｃｒ 镀层没有针孔, 只有少数细小的裂纹。对Ｃｒ３ ＋ 水溶液中电镀Ｃｒ 的工艺条件和络合剂、稳定剂、添加剂的作用进行了探讨     

甲酸盐型三价铬电镀液电化学研究

研究了甲酸盐型三价铬镀液的电化学特性，通过循环伏安、动电位扫描、恒电位电镀、恒电流电镀证实了Ｃｒ＾３＋在电位负于－１．３Ｖ后开始还原为Ｃｒ，在－０．９Ｖ－１．３Ｖ之间还原为Ｃｒ＾２＋，Ｃｒ＾２＋是暂时的，在溶液中极不稳定，但能加速配体交换反应。讨论了Ｃ＾３＋电沉积的是极过程和镀层不能加厚的原因。     

3Cr2W8V钢粉末钛铬共渗的研究

研究了３Ｃｒ２Ｗ８Ｖ钢粉末钛铬共渗的渗剂、工艺参数及其对共渗层的影响，结果表明，共渗温度等工艺参数对共渗层的影响遵循扩散的一般规律，１０００℃保温４ｈ条件下，能得到较佳的共渗层，３Ｃｒ２Ｗ８Ｖ钢钛铬共渗层的相结构为（Ｃｒ，Ｆｅ）７Ｃ３和Ｃｒ７Ｃ３，其表面硬度可达１６８２－１９５０ＨＶ０．１，耐磨、抗氧化、耐腐蚀性能均有显著提高，共渗试样可进行热处理，以提高基体性能。     

化学镀Ni—Cr—P合金镀层在NaCli溶液中的耐蚀性

用电化学方法研究了化学镀Ｎｉ－Ｃｒ－Ｐ合金镀层在３．５％ＮａＣｌ溶液中的耐蚀性,结果表明Ｎｉ－Ｃｒ－Ｐ镀层与Ｎｉ－Ｐ镀层的阳极极化曲线形状相似,自腐蚀电位正移１５０ｍＶ以上,自腐蚀电流降低近３倍,在钝化区的阳极是约１个数量级,镀层的耐蚀性提高。     

电沉积非晶态Cr—Fe—C合金镀层结构与性能研究

采用以三价铬为主盐的铬合金电镀工艺,对获得的Ｃｒ－Ｆｅ－Ｃ合金镀层的化学成分、结构、性能及其成因进行研究,结果表明,这种含铁量为２０％,含碳为５％左右的镀层为非晶态结构,含有大量微裂纹,微观上镀层表面呈结瘤状,热处理后可出现极明显的硬化现象,并伴随镀层逐渐向晶态转化。     

用铬传感器测定碳饱和铁液中的Cr的活度

用ＺｒＯ２（ＭｇＯ）固体电解质，以ＣａＳｉＯ３＋Ｃｒ２Ｏ３作为辅助电极，组成铬传感探头：ＭｏＣｒ，Ｃｒ２Ｏ３，ＺｒＯ２（ＭｇＯ）ＣａＳｉＯ３，Ｃｒ２Ｏ３Ｃｒ）ＦｅＭｏ－ＺｒＯ２于１７５３Ｋ测定了碳饱和铁液中Ｃｒ的活度，该探头响应快，约２－３ｓ即可得到稳定的电动势值，测定误差为±１－２ｍＶ，Ｃｒ的活度与Ｃｒ的浓度之间符合理论关系。     

电沉积非晶态铬镀层的组织与性能

用电沉积方法制备了非晶态铬镀层，用X射线衍射仪分析了镀层的相结构，对镀层的组织与性能以及热处理对镀层组织与性能的影响进行了研究。结果表明，非晶态铬镀层的硬度值约为969HV0．025，热处理后由于Cr7C3相的析出使硬度最高可升至1345HV0．025，非晶态铬镀层表现出良好的耐磨性和耐蚀性能，明显优于普通晶态铬镀层。热处理后，镀层与基体的结合力也有明显提高。     

离子束增强沉积CrN镀层及热力学分析

利用ＩＢＥＤ 技术,在Ｓｉ（１１１） 和ＧＣｒ１５ 轴承钢基体上沉积ＣｒＮ 镀层。研究Ｎ＋ ＋ Ｎ＋２ 离子轰击能量和Ｎｉｏｎｓ／Ｃｒａｔｏｍｓ 到达比对镀层组织结构的影响。结果表明,氮离子轰击能量的增加促进ＣｒＮＣｒＮ（２００） 择尤生长;但Ｎｉｏｎｓ／Ｃｒ ａｔｏｍｓ 比从１．４５ ×１０ － ２ 增至３．６７ ×１０ － ２ 和５．８７ ×１０ － ２时,镀层中ＣｒＮ 组分非但没有增多,Ｃｒ 反而以Ｃｒ２Ｏ３ 形态存在。     

非晶态Fe—W镀层铬酸盐钝化膜耐蚀机理探讨

Ｆｅ－Ｗ非晶镀层经铬酸盐钝化处理，可获得有装饰的含Ｃｒ钝化膜，经测定，孔蚀电位较钝化前正移１．６８Ｖ，明显改善了抗Ｃｌ＾－腐蚀的能力，ＡＥＳ与ＸＰＳ的分析结果表明，钝化膜由内外两层构成，外层为Ｆｅ（ＣｒＯ４）３．Ｃｒ２（ＣｒＯ４）３／Ｃｒ２（Ｃｒ２Ｏ７）３．Ｆｅ（ＯＨ）３／ＦｅＯＯＨ．ＷＯ３．ｎＨ２Ｏ等化合物，内层由Ｃｒ２Ｏ３，ＣｒＯ３，ＣｒＯＯＨ，ＦｅＯ，Ｆｅ２Ｏ３及ＷＯ３组成。钝化膜厚度约为６     

电沉积Cr—P合金及其耐蚀性的研究

在三价镀铬溶液中添加次磷酸钠，制得了Ｃｒ－Ｐ合金镀层，研究了电沉积条件对镀层成份的影响和镀层在１ｍｏｌ／Ｌ盐酸和０．５ｍｏｌ／Ｌ硫酸中的电化学行为，磷含量大于５ｗｔ％时，合金镀层具有极好的耐蚀性。     

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.     

Secondary Recrystallization Behaviors of Grain-Oriented 6.5 wt% Silicon Steel Sheets Produced by Rolling and Nitriding Processes

By rolling and nitriding processes, 0.23- to 0.3-mm-thick grain-oriented 6.5 wt% silicon steel sheets were produced. The core losses of grain-oriented 6.5 wt% silicon steel at frequencies ranging from 400 Hz to 20 k Hz were lower than that of the grain-oriented 3 wt% silicon steel with the same thickness by 16.6–35.8%. The secondary recrystallization behavior was investigated by scanning electron microscopy, energy-dispersive spectroscopy, and electron backscattered diffraction. The results show that the secondary recrystallization in high-silicon steel sheets develops more completely as the nitrogen content increases after nitriding, secondary recrystallized grain sizes become larger, and the sharpness of Goss texture increases. Because more {110}116 grains in the subsurface and the central layer of the sheets have a lot of 20°–45° high-energy boundaries in addition to Goss grains, {110}116 can be the main component through selective growth during secondary recrystallization when the inhibitor quantity is not enough and inhibitor intensity is weaker. The increases in nitrogen content can increase the inhibitor intensity and hinder abnormal growth of a mount of {110}116 grains and therefore enhance the sharpness of Goss texture.     

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 80?滋m, 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.     

Microstructure,Mechanical Properties and Corrosion Behavior of Extruded Mg–Zn–Ag Alloys with Single-Phase Structure

Mg–Zn–Ag alloys have been extensively studied in recent years for potential biodegradable implants due to their unique mechanical properties,biodegradability and biocompatibility.In the present study,Mg–3Zn-x Ag(wt%,x=0.2,0.5 and0.8)alloys with single-phase crystal structure were prepared by backward extrusion at 340°C.The addition of Ag element into Mg–3Zn slightly influences the ultimate tensile strength and microstructure,but the elongation firstly increases from12%to 19.8%and then decreases from 19.8%to 9.9%with the increment of Ag concentration.The tensile yield strength,ultimate tensile strength and elongation of Mg–3Zn–0.2Ag alloy reach up to 142,234 MPa and 19.8%,respectively,which are the best mechanical performance of Mg–Zn–Ag alloys in the present work.The extruded Mg–3Zn–0.2Ag alloy also possesses the best corrosion behavior with the corresponding corrosion rate of 3.2 mm/year in immersion test,which could be explained by the single-phase and uniformly distributed grain structure,and the fewer twinning.     

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.