铜金粉的颜色及其影响因素

利用分光光度计对国内外铜金粉的颜色进行了测试，研究了铜金粉的成分、微观状态对颜色的影响。结果表明：铜金粉颜色可以用色彩三要素进行描述，其中铜金粉的色相只与合金成分有关，而与铜金粉片的大小、形状及粒度分布无关；明度和纯度与铜金粉片在油墨层中定向排列状态、片的大小、形状及粒度分布有关，而与成分无关；合金成分的微小波动不会引起铜金粉色相的明显改变。     

梯度金属多孔材料孔结构研究

利用离心沉积技术在多孔管内壁上制备了不同粒度的镍和不锈钢多孔梯度层,研究不同粒度的粉末以及梯度层厚度对梯度层孔隙性能的影响.结果表明,梯度层透气系数与中流量孔在梯度层粒度为5 μm以下急剧减小,当梯度层粉末粒度为13.6μm、梯度层厚度小于20 μm时,梯度层厚度对其孔径分布与透气系数影响不大;当梯度层粉末粒度为2.7μm时,梯度层的最佳匹配厚度是50μm.     

高能球磨制备Ti(C,N)基金属陶瓷硬质相超微粉

对Ti(C,N)基金属陶瓷硬质相TiC、TiN、WC原料粉在不同球料比、不同球磨时间试验条件下进行高能球磨,探讨了TiC、TiN、WC粉体的高能球磨超细化机理和球磨行为特征。试验表明随球料比和球磨时间的增加,TiC、TiN、WC粉体得到细化,但达到一个极小值后细化趋于稳定。利用沉降法测试粉末粒度分布并在扫描电镜下观察粉末的形貌和粒度,发现在10∶1球料比下球磨96h后可以有效制备得颗粒粒度为0.20μm的金属陶瓷硬质相超微粉。     

Bi-2223/Ag超导带材前驱粉与热处理的匹配问题

研究了Bi-2223／Ag高温超导带材的前驱粉与后续热处理工艺之间的匹配问题。实验采用A，B，C3种不同的前驱粉。A粉是成分配比为2223的喷雾热分解单粉，B粉和C粉都是2212加CaCuO，组分的2223双粉。B粉和C粉的区别在于，2212加CaCuO，混合后的除碳处理工艺不同。B粉为800℃，3h，C粉为830℃，10h。利用激光粒度分析仪（RSA）和扫描电镜（SEM）对这3种前驱粉的粒度进行了表征，并用X射线衍射仪（XRD）对用这3种粉分别制成的带材经第1次热处理（HT1）后的2223成相率和相结构进行分析，从而找出它们各自对应的最佳HT1工艺。采用四引线法在77K，0T下测试经中间轧制和第2次热处理（HT2）后的临界电流（五），以确定其对应之最佳HT2工艺。RSA和SEM分析表明：A粉颗粒度明显细小，平均中径粒度为1．5μm，且粒径分布区域集中，B粉约3μm，粒径分布较分散，而C粉为4-5μm。研究结果证明：前驱粉的特性直接影响着超导带材的最终超导性能。一种特定的前驱粉，对应着一种特定的最佳HT1和HT2工艺。只有在二者匹配良好前提下，才能使前驱粉的性能得以发掘。     

WCu假合金熔渗过程数值分析

利用有限元软件模拟WCu合金的熔渗过程。根据W颗粒骨架实际形貌,建立了球形颗粒堆积骨架模型;在等径与非等径多孔体系内部,分析了铜液在渗流路径中的压力及速度矢量分布;得出了当W粉平均粒度为5μm时,铜液在多孔体系内部的熔渗深度与熔渗时间的关系,模拟结果与实验相符。     

颗粒度对贮氢合金MlNi_(3.65)Co_(0.75)Mn_(0.4)Al_(0.2)电化学性能的影响

研究了贮氢合金 Ml Ni3.6 5Co0 .75Mn0 .4 Al0 .2 的颗粒度及粒度分布均匀性对其电化学性能的影响。结果表明 :在2 0 0 m A/g(以贮氢合金的质量计算 ,下同 )的充放电电流下 ,合金的粒度越小 ,首次放电容量越大 ,且活化速度越快 ,但其饱和容量 (活化后稳定的放电容量 )随粒度的增大而增加 ,且在某个最佳粒度时达到最大值 ,然后又逐渐降低 ;该合金的高倍率放电容量与其粒度之间也有相同的规律 ,只是在不同的放电电流下最佳粒度值不同 ,当放电电流小于 60 0 m A/g时 ,3 0μm～ 76μm合金粉的放电容量最大 ,当放电电流等于或大于 60 0 m A/g时 ,4 0μm～ 5 0μm合金粉的放电容量最大 ;放电电流越大 ,颗粒度对合金粉电化学性能的影响越显著 ;在充放电电流为 3 0 0 m A/g时 ,除3 0μm以下的合金粉性能衰减较快外 ,其余各个粒度的合金粉的性能衰减速度几乎相等 ;均匀的粒度分布有利于合金粉电化学性能的提高。     

高能球磨制备超细TiH_2粉研究

利用氢化钛的氢脆性,在室温下通过高能球磨制备超细氢化钛粉。研究不同球磨条件对粉末粒度和形貌的影响,并对制备的粉末进行了扫描电镜分析。结果表明,球磨时间对粉末粒度的影响很大,粉末粒度在球磨初期迅速减小,球磨2min粉末迅速细化,粒度约为5μm~10μm。粒度为40μm的氢化钛粉,用庚烷保护湿磨30min时粒度达到1μm以下,球磨60min即可制得粒度为0.1μm的超细氢化钛粉。     

NaCl包覆/氢化脱氢联合法制备超细钛粉及其性能

以海绵钛为原料,采用经过氢化破碎、阻止剂包覆、真空脱氢以及阻止剂脱除的方法制备超细钛粉。采用TEM、SEM以及激光粒度测试等手段研究制备过程中工艺参数对钛粉形貌、粒度及氧含量的影响,探讨阻止剂的晶粒长大抑制机理。结果表明:海绵钛在700℃、2 h渗氢后经过球磨5 h,粉末中位径(D50)达到2.61μm,以NaCl为阻止剂对氢化粉末进行包覆,经630℃、2 h脱氢并脱除阻止剂后,制得的超细钛粉呈不规则形状,中位径达6.16μm,氧含量为0.89%(质量分数);阻止剂的引入造成钛粉氧含量的微量增加;通过阻止剂包覆,在粉末颗粒表面形成厚度为5~10 nm的隔离层,阻碍了加热过程中Ti颗粒表面的原子扩散,从而阻止加热脱氢过程中粉末颗粒的长大。     

复合表面活性剂对铜金粉印金光泽度的影响

采用物理化学法,用5种不同配比的复合表面活性剂对铜金粉进行表面改性处理。通过对铜金粉的凹印印金光泽度、润湿性测试和微观形貌观察,分析复配比例和添加量对铜金粉印金光泽度的影响机理。结果表明:经硬脂酸与线性高分子聚合物SA以1:0.1复配的复合表面活性剂在添加量为0.2%时改性的铜金粉的光泽度最高,其光泽度值达99.67。铜金粉的凹印印金光泽度与铜金粉在连接料中的润湿性有关,可通过降低铜金粉的润湿性和提高铜金粉在连接料中的漂浮性来进一步提高铜金粉的凹印印金光泽度。     

自贡厂研制成超细WC粉和超细硬质合金牌号

自贡硬质合金厂承担了作为“八五”国家级重点开发项目之一超细WC粉及4个超细硬质合金牌号的研制。该厂的科技人员与中南工大粉冶所紧密合作，在研制过程中解决了两大难题。一是制粉问题，采用一种较为特殊的，称之谓“气相还原──—碳化法”，即以高纯鹤的化合物为原料，添加少量Cr、V等为抑制剂，能工业生产BET平均粒度＜0．15μm，小角度X射线散射测定＜0．1μm，粒度分布窄的超细WC粉。与此同时还研制成超细Co粉，平均粒度（朋T）＜0.4μmm；二是解决了利用上还超细WC粉和钴粉配制的超细合金在烧结过程中的晶粒长大问题。该厂研…     

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.