LF炉精炼过程钢液温度预报及控制

LF炉精炼过程钢液温度预报及控制是炼钢工艺过程优化的主要内容,它不但影响能否为连铸提供温度合格的钢液,能否实现节奏调整及多炉连浇,而且对整个炼钢过程的节能降耗以及现场的操作影响很大。通过LF炉精炼过程钢液温度预报及控制研究,建立LF炉升温期钢液目标温度数学模型,给出LF炉热效率公式及确定损失能量的方法,将供电制度与钢液温度控制结合在一起,给出LF炉精炼过程供电原则。其研究结果有利于进一步强化LF炉精炼过程,增加LF炉对电炉-连铸流程节奏的调节能力,实现多炉连浇及高效节能。     

Strategies for CO2 capture from different CO2 emission sources by vacuum swing adsorption technology☆

Different VSA(Vacuum Swing Adsorption) cycles and process schemes have been evaluated to find suitable process configurations for effectively separating CO2 from flue gases from different industrial sectors. The cycles were studied using an adsorption simulator developed in our research group, which has been successfully used to predict experimental results over several years. Commercial zeolite APGIII and granular activated carbon were used as the adsorbents. Three-bed VSA cycles with- and without-product purge and 2-stage VSA systems have been investigated. It was found that for a feed gas containing 15% CO2(representing flue gas from power plants), high CO2 purities and recoveries could be obtained using a three-bed zeolite APGIII VSA unit for one stage capture, but with more stringent conditions such as deeper vacuum pressures of 1–3 k Pa. 2-stage VSA process operated in series allowed us to use simple process steps and operate at more realistic vacuum pressures. With a vacuum pressure of 10 k Pa, final CO2 purity of 95.3% with a recovery of 98.2% were obtained at specific power consumption of 0.55 MJ·(kg CO2)-1from feed gas containing15% CO2. These numbers compare very well with those obtained from a single stage process operating at1 k Pa vacuum pressure. The feed CO2 concentration was very influential in determining the desorption pressure necessary to achieve high separation efficiency. For feed gases containing N 30% CO2, a singlestage VSA capture process operating at moderate vacuum pressure and without a product purge, can achieve very high product purities and recoveries.     

重轨钢连铸坯内部质量控制技术

针对攀钢大方坯连铸机投产初期重轨钢连铸坯中心疏松、中心偏析等内部缺陷较严重的问题,研究应用了提高重轨钢连铸坯内部质量的控制技术,包括凝固末端动态轻压下、结晶器电磁搅拌、二冷动态控制、连铸拉速与钢水温度优化控制等核心工艺技术.生产实践表明,重轨钢连铸坯综合合格率达到99.97%,铸坯中心疏松≤1.0级,中心偏析≤1.0级,中心缩孔≤1.0级,中心裂纹≤0.5级,中间裂纹≤0.5级,角部内裂≤0.5级,中心碳偏析指数≤1.05,由连铸坯轧成重轨的内部质量和力学性能满足时速350 km高速铁路用钢轨的要求.     

Synthesis and electrochemical performances of spinel LiCr0.1Ni0.4Mn1.5O4 compound

The spinel compound LiCr_0.1Ni_0.4Mn_1.5O₄ was synthesized by a solid reaction method and a sol-gel method using citric acid as chelating agent. The pure phase LiCr_0.1Ni_0.4Mn_1.5O₄ was obtained by the wet method. The electrochemical performances of the pure phase sample were measured at different current rates. There were three voltage plateaus at about 4.9, 4.7 and 4.0 V in the charge-discharge curves, which were attributed to the oxidation/reduction of chromium, nickel and manganese respectively. In the range of 3.5-5.0 V, its first discharge capacity was 143, 118 and 111 mAh/g corresponding to current densities of 1.0, 4.0 and 5.0 mA/cm², respectively. After 50 cycles, the capacity retention remained well at the current densities of 1.0, 4.0 and 5.0 mA/cm². The electrochemical performances of pure phase LiCr_0.1Ni_0.4Mn_1.5O₄ at 55 °C was also measured, and the results were discussed.     

Synthesis of Al2O3/TiCN-0.2%Y2O3 Composite by Hot Pressing

Al2O3/TiCN composites were synthesized by hot pressing.The influences of components and HP temperature on mechanical properties,such as bending strength,breaking tenacity and Vickers hardness were investigated.The results showed that the mechanical properties of Al2O3/TiCN composite increased with temperature when hot pressing temperature is below 1650 ℃.The mechanical properties reached their maximums when the composites were sintered at 1650 ℃ for 30 min under hot pressing pressure of 35 MPa,the value of bending strength,breaking tenacity and Vickers hardness was 1015 MPa,6.89 MPa·m1/2,and 20.82 MPa,respectively.When hot pressing temperature was above 1650 ℃,density decreased because of decomposition with increased temperature,and mechanical properties dropped because of rapid growth of grains in size at high temperature.Microstructure analysis showed that the addition of Y2O3 led to the formation of YAG phase so as to inhibit the growth of crystals.This helped to improve breaking tenacity of the composites.TiCN particles with diameters of 1 μm dispersed at Al2O3 grain boundaries,inhibited grain growth and enhanced mechanical properties of the composites.SEM study of the propagation of indentation cracks showed that the bridge linking behavior between matrix and strengthening phase might lead to the formation of the coexisted field of crack deflection,branching and bridge linking.The mechanism of this phenomenon was that the addition of Y2O3 improved the dispersion of TiCN particles so as to enhance the tenacity of the composites.The breaking tenacity was changed from 5.94 to 6.89 MPa·m1/2.     

酸性加压氧化分解辉钼精矿的实验研究

采用酸性加压氧化法分解辉钼精矿,考察了几种因素对钼精矿转化率和浸出率的影响。实验结果表明,对含钼49.68%的钼精矿控制硝酸浓度在28.8 g.L-1,液固比为5,氧分压为350 kPa条件下,160℃反应3 h,钼的氧化率可以达到99%以上,钼的浸出率小于12%。     

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.     

激光熔凝处理对NiTi形状记忆合金微动磨损性能的影响

采用高功率连续波固体Nd:YAG激光器,对NiTi形状记忆合金进行激光表面熔凝处理,利用SRVⅢ摩擦磨损试验机考察激光熔凝处理对NiTi形状记忆合金微动磨损性能的影响.采用扫描电子显微镜及能谱仪分析NiTi形状记忆合金表面磨痕形貌及磨损产物成分;用形貌仪测量样品表面磨痕深度,并对磨损体积进行计算.结果表明,与NiTi合金相比,熔凝层摩擦系数,磨损体积均显著降低,表明激光熔凝处理提高了Ni-Ti合金的耐微动磨损性能.NiTi合金微动磨损机理主要表现为氧化和磨粒磨损,而Ni-Ti合金激光熔凝层磨损机制主要以疲劳剥层理论及磨粒磨损为主.     

TMCP工艺对车轮钢组织及扩孔性能的影响

采用TMCP(Thermo Mechanical Controlled Process)实验,研究了不同冷却方式对汽车车轮用低碳FB钢的组织及扩孔性能的影响,以及FB钢扩孔时的断裂类型及断裂机理。结果表明,采用连续冷却的实验钢,得到了针状铁素体＋贝氏体组织,针状铁素体明显降低了两相硬度比,改善了扩孔性能。FB钢在扩孔过程中的断裂机理为微孔聚集的韧性断裂。实验结果可为进一步研究低碳FB钢在车轮上的应用提供实验依据。     

空心管坯电渣重熔技术

在分析了几种大口径厚壁管的生产方法后,发现电渣重熔管坯技术可解决其他方法生产大口径厚壁管生产过程中存在的成本高、铸件质量低的问题.通过对电渣重熔管坯技术的原理及几项关键技术的分析,证实电渣重熔管坯技术是可行的,并且具有广泛的应用前景和经济价值.