造粒填充的实验研究

为了研究造粒填充过程中的空隙度及实现烧结生产的优化控制，需了解影响空隙度的因素以及空隙度与这些影响因素之间的关系，因此进行了水分含量和造粒体积分数对空隙度的影响实验。实验结果表明，二元填充体系的空隙度随组元体积分数的增加一般呈先降后加的趋势，在二元填充体系的空隙度曲线上一般存在一极小值点；不同水分含量的二元填充体系空隙度极小值出现的位置不同，随水分的增加极小空隙度点右移；当向同一种组元中填加大粒度的颗粒时，空隙度随大粒度颗粒体积分数的增加则变化明显，而向该组元中添加小粒度颗粒时空隙度随小粒度颗粒体积分数的增加则变化不明显。     

Al2O3/TiCN-0.2% Y2O3 Composite Prepared by HP and Its Cutting Performance

Al₂O₃/TiCN-0.2% Y₂O₃ composites were fabricated by hot pressing sintering. The effect on mechanical property and microstructure of the sample composition and HP temperate was investigated. The results of Al₂O₃/TiCN-0.2% Y₂O₃ were satisfied. The bending strength, fracture toughness, Vickers hardness was respectively 1015 MPa, 6.89 MPa·m^1/2 20.82 MPa at 1650 °C for 20 min. Good wear resistance was found for the kind of ceramic material when used as cutting tools in the machining of the hardened carbon steel. By the compared experiment for the cutting performances, it could be seen that the performance of this composite material was better than that of the ceramic tool material YT15 for continuously cutting quenched steel. This kind of composite tool material is suitable for continuously cutting quenched steel No.45, especially intermittently cutting quenched steel.     

酒钢板坯连铸漏钢成因分析及预防措施

对于酒钢4号、5号板坯连铸机的主要产品Q235及低合金钢的生产,近几年由于操作、设备等因素造成较高的漏钢率,给生产和设备造成极大危害.分析了漏钢的原因,在无漏钢预警系统的前提下制定了针对粘结漏钢与裂纹漏钢的预防措施,使板坯漏钢率显著下降.     

Studies on copper coating on carbon fibers

The weak interface bonding of metal matrix reinforced by carbon fibers is the central problem of fabricating such composites. Depositing copper coating on carbon fibers is regarded as a feasible method to solve the problem. In this paper, copper coating has been deposited on the fibers through both electroless deposition and electroplating methods. Two kinds of complexing agents and two stabilizing agents are taken during the electroless plating process. The solution is stable, and little extraneous component is absorbed on the surface. After adding additive agents and increasing the concentration of H2SO4 to the acid cupric sulfate electrolyte, the “black core“ during usual electroplating process is avoided. The quality of copper coating is analyzed using SEM and XRD, etc.     

Microstructure of A γ−α2−β TiAl alloy containing iron and vanadium

Ordered ß-phase (B2 CsCl structure) has been identified in a Ti-45.5 at.% Al-1.6 at.% Fe-1.1 at.% V-0.7 at.% B alloy being developed for high temperature applications. Selected area electron diffraction has been used to identify the orientation relationships and interface planes of the ß-phase with the bulk γ-TiAl and α₂-Ti₃Al phases. Energy dispersive X-ray spectroscopy indicates that the ß-phase has approximately the same Ti/Al ratio as the α₂-Ti₃Al phase, and is stabilized within the microstructure by Fe and V. Channeling enhanced microanalysis studied (ALCHEMI) show that the Fe and V both occupy the same sublattice as the Al atoms in the cubic ß-phase structure, and that Fe occupies the Al sites in the γ-phase. Fe and V are concentrated in the ß-phase, which effectively getters these dopants from the γ and α₂ phases. Titanium ferride precipitates, probably FeTi, have been observed within the ß-phase.     

Thermoelectric Characterization of （Na1-yMy）1.6Co2O4 （M=K, Ca, Sr）

Oxide materials NaCo2O4 and (Na1-yMy)1.6Co2O4 (M=K, 0.05≤y≤0.35; M=Ca, Sr, 0.10≤y≤0.40) were prepared by a sol-gel method. Experimental results indicated that the Seebeck coefficient and the Powerfactor of NaCo2O4 were improved by doping Ca and Sr but not by K. The Power-factor of NaCo2O4 is in its maximum, 1.68×10-4 W·m-1·K-2 and 11% bigger than that of the original one when the dopant fraction of Ca was 0.1. Doping Sr makes NaCo2O4 have the biggest Power-factor, 1.68×10-4 W·m-1·K-2 that is 50% bigger than the non-doping oxide. The experimental results indicate that suitable dopants and addition amounts could improve the thermoelectric properties of NaCo2O4 greatly.     

铝熔体中磁性杂质颗粒的电磁分离

分析了磁性杂质颗粒在电磁场中的受力情况,采用磁平衡法测量了铝熔体中两种典型富铁相杂质颗粒的磁化率,指出铝熔体中的富铁相杂质是顺磁性物质,在电磁场中受到电磁力和磁场力的驱动作用,确定其在分离器上的聚集方式．静态电磁分离试验结果表明,当磁场强度大于145mT时,电磁力起主要作用;当磁场强度小于120mT时,磁场力起主要作用．     

Effects of Sn Addition on Core Loss and Texture in Non-oriented Electrical Steels

 The effects of Sn addition on core loss and texture of non oriented electrical steels were investigated. Experiments revealed that the core loss of non oriented electrical steels could be obviously decreased and the intensity of {111} texture and {112} texture of final annealed specimens could be markedly reduced by Sn addition. The reasons for reducing core loss and the intensity of unfavorable texture were analyzed.     

Mechanical properties of nanocrystalline nickel films deposited by pulse plating

This paper reports the mechanical properties of Ni films fabricated by pulse electrodeposition. Transmission electron microscope revealed that the prepared films had an average grain size of 25 nm with a narrow size distribution and the absence of dislocations. Small grain size leads to an increasing hardness as high as 7.8 GPa while Young's moduli keep a constant bulk value of 215 GPa, resulting in an increasing ratio of hardness (H) to elastic modulus (E). Interestingly, the wear resistance was also improved significantly. Under a constant normal load of 500 μN, the penetration depths of indenter slightly increased from 25 nm to 30 nm and the coefficient of friction varied from 0.12 to 0.20, depending on sliding scans. Depth sensing instrumented indentation experiments performed at different loading rates on specimens revealed an increasing rate-sensitivity of hardness, which concerns with a significantly small activation volume for plastic flow.     

泡沫铝表面镀镍及其性能

为提高泡沫铝耐高温及耐蚀性,对其表面电镀镍层。采用扫描电镜观察镀层的表面形貌,进行镀层与基体的结合力测试、常温及650℃以上高温压缩测试及常温下中性电化学腐蚀研究。结果表明:一定范围内,电流密度越大,镀层结晶越致密;但电流密度过大(≥3 A/dm2)时,镀层区域结晶反而粗大;由于走位剂的添加,深镀能力提高;镀层与基体结合良好,在电流密度为1 A/dm2、镀层厚度为28~30μm时,镍层与基体界面结合力达到最大;镀镍后的泡沫铝压缩弹性模量提高了2.3倍,平台应力提高了1.5倍,由于镍层的存在,泡沫铝在650℃以上高温压缩时强度依然存在;镀镍后泡沫铝自腐蚀电位、电蚀电位、致钝电位分别正向移动238、51和220 mV,耐腐蚀性能提高。