不同粒级骨料制备冶炼石英坩埚用高纯石墨材料的研究

分别选取1～0 mm粗结构、0.5～0 mm中粗结构和0.15～0 mm细结构3种粒级煅烧石油焦作为骨料,以中温煤沥青作为黏结剂和浸渍剂,制备出冶炼石英坩埚用高纯石墨材料.研究了不同粒级骨料对高纯石墨材料性能和显微结构的影响.研究表明:0.15～0 mm细结构样品的机械性能最好,1～0 mm粗结构的最差.X射线衍射(XRD)和扫描电镜(SEM)分析结果显示,1～0mm粗结构样品的石墨化程度不如0.5～0 mm中粗结构和0.15～0 mm细结构样品.综合热分析(TG-DSC)结果表明,1～0 mm粗结构样品的热失重温度区间主要集中在680～880℃,其抗氧化能力相对较差.     

Making dense fine-grained large graphite blocks

Ways are considered of making large blocks of fine-grained graphite on the basis of fired coke. One method is to press the hot mass immediately after mixing instead of making from this mass a press powder and subsequently pressing it. Pressing the hot mass also reduces the pressing pressure. This eliminates laborious and polluting operations: cooling the mass after mixing with subsequent crushing. Also, pressing the hot mass immediately after mixing appreciably raises the yield of acceptable blanks after heat treatment (firing and graphitization). __________ Translated from Novye Ogneupory, No. 3, pp. 140–142, March, 2008.     

A new crucible design of the arc-discharge method for the synthesis of graphite encapsulated metal (GEM) nanoparticles

Graphite encapsulated metal (GEM) nanocrystal is a core-shell structured nanomaterial which is capable of surviving in severe environments, such as strong-acid or strongly-oxidizing conditions. Many researches have proven GEM to be useful for its potential multiple applications. However, there is a serious problem: its low production rate hinders future research on possible applications. Although the tungsten arc-discharge method produces more GEM nanoparticles than all the other methods do, the production rate remains unsatisfactory.Based on a previous study, it is known that the temperature gradient in the molten liquid metal pool during arcing is inadequate, i.e., the bottom is cooler than its surroundings, thus preventing the occurrence of convection and the homogeneous evaporation process. In this study, a new crucible design, with a thermal insulating alumina piece at the bottom of the graphite crucible, effectively modifies the temperature gradient inside the molten liquid pool. As a result, the as-made production rate approximately quadruples. This work demonstrates, as attested by experimental evidence, how an alumina piece can effectively change the temperature profile in the crucible and facilitate the synthesis of GEM in a tungsten arc-discharge system.     

无硫高膨胀体积膨胀石墨的制备

采用化学氧化法,以粒径为180 μm的天然鳞片石墨为原料,在混酸（乙酸酐-磷酸-高氯酸）混合固体助氧化剂（高锰酸钾-重铬酸钾）体系下制得无硫可膨胀石墨。确定最佳合成条件为：m（鳞片石墨）∶V（混酸）∶m（高锰酸钾）∶m（重铬酸钾）=1（g）∶4（mL）∶0.1（g）∶0.1（g）,50 ℃反应60 min,40 ℃干燥2 h。在此条件下得到初始膨胀温度为 200 ℃的无硫可膨胀石墨,在500 ℃下的最大膨胀体积高达665 mL/g。通过SEM、FT-IR、XRD及TGA测试对鳞片石墨、可膨胀石墨和膨胀石墨进行结构、形貌、官能团分析。结果表明：可膨胀石墨片层间距增大,成功插入高氯酸、磷酸、乙酸酐;且经膨化后,得到纯度较高、孔隙较发达且片层晶体结构未改变的无硫高膨胀体积膨胀石墨。     

Factors determining the temperature coefficient of linear expansion of graphite

The technological factors determining the temperature coefficient of linear expansion of electrode and nipple graphite are considered. The TCLE is determined with the help of a DID-1 interference differential dilatometer in a range of working temperatures of 30 — 98°C. Many years of measurements have shown that the TCLE of graphite is sensitive to the variation of some technological factors the optimization of which makes it possible to decrease substantially the TCLE of graphitized nipples and determine ways of further improving the manufacturing process of graphite with an enhanced heat resistance.     

Ways of improving the quality of fine-grained isotropic graphite in large objects

The main stages are considered in the development of equipment and technology for preparing large objects of hydrostatic compaction made of fine-grained isotropic graphite. The main organizations and workers whose efforts in Russia were the first to prepare this new form of carbon material are indicated. Some technical solutions are provided that make it possible to overcome difficulties in preparing high quality material of this class, and structural layouts for a hydrostat and its individual assemblies are presented. __________ Translated from Novye Ogneupory, No. 2, pp. 26–30, February 2008.     

真空冶炼用MgO-CaO坩埚的研制

为了降低真空冶炼用MgO坩埚因MgO的高温不稳定性对冶炼合金造成的影响,同时发挥CaO的脱硫作用,以w(MgO CaO)>97%的MgO-CaO熟料为原料,在对MgO-CaO熟料进行水化试验和烧结试验研究的基础上,研制了MgO-CaO坩埚,并且与CaO坩埚一起对一种纯金属和同材质的高温合金进行了对比冶炼试验。结果表明:MgO-CaO熟料的抗水化性远高于石灰熟料的;在添加适当种类和数量的烧结助剂后,MgO-CaO熟料的可烧结性明显改善;MgO-CaO坩埚的冶炼效果达到甚至超过了CaO坩埚。     

Corrosion resistance of calcium zirconate crucible to titanium-copper melts

The corrosion resistance of refractory materials to the titanium alloy melts is vital for the production of titanium alloys by vacuum induction melting. In this study, the corrosion behavior of calcia-stabilized zirconia, solid state synthesized calcium zirconate, and fused calcium zirconate refractory suffering Ti-5 wt% Cu melts were investigated at 1680 ℃ for 15 min of soaking time by the cup test method. It was found that the three crucibles directly dissolved into the titanium melt, then generated Ti (Zr, O) and CaZrO₃ in the infiltration layer, and eventually developed a porous Ti₃O layer in the lining. Besides, the contamination of Ti-5 wt% Cu alloy (oxygen: 5.3 wt%; zirconium: 6.01 wt%; calcium: 0.42 wt%) by fused calcium zirconate crucible was significantly less than the solid state synthesized one (oxygen: 5.83 wt%; zirconium: 6.14 wt%; calcium: 0.43 wt%), implying that the production method of calcium zirconate notably affected the impurity of titanium alloys.     

熔制玻璃用坩埚抗热震性的改进

在粘土 -蜡石质玻璃用坩埚的配方基础上 ,研究了蜡石的粒径和加入量的变化对试样抗热震性的影响。结果发现 :减小蜡石的粒径与加入量均可提高试样的抗热震性 ,但减小蜡石粒径对提高试样的抗热震性更有效 ;在配料中引入少量的蓝晶石细粉 ,可明显提高试样的抗热震性。     

Interaction of molten metal with a crucible of fused lime

Conclusions During the in-vacuo smelting of a metal in a crucible produced of fused lime the metal oxides interact with the CaO with the result that the amount of inclusions in the alloy decreases.During the smelting of a metal containing significant amounts of silicon and nickel, dicalcium and tricalcium silicates, merwinite, and helenite are formed in the hot zone of the crucible. The interspaces contain Ni(Fe, Mn)₂O₄ and Ca(Mn, Fe)O₃. The cold zone (i. e., the outside part of the wall) undergoes little change and its microstructure consists of lime grains and thin interlayers of solid solutions of calcium ferrites and aluminoferrites.During the smelting of a metal not containing silicon the crucible is impregnated with nickel and iron oxides throughout the thickness of the wall as a result of the formation in the hot zone of Ni(Fe, Al)₂O₄ which fills the interspace between the lime grains. In the cold zone of the crucible dicalcium ferrite predominates in the interspace between the lime grains.Translated from Ogneupory, No. 2, pp. 47–50, February, 1978.     

钛酸铝坩埚的制备及抗热震机理

采用一步法制各钛酸铝坩埚并应用于齿科合金的铸造过程，在室温～１６５０℃的高温差及温度急变条件下，经２０次重复使用钛酸铝坩埚未发生热震开裂。试验结果表明：钛酸铝坩埚优良的抗热震性能归因于其细晶结构，以及久酸铝各晶轴热膨胀巨大差异产生的众多微裂纹。     

浓缩石墨换热器大面积爆管原因分析及预防

从黄麦岭磷化工集团公司石墨管清理不彻底、壳程压力高、蒸汽带水严重、旁路及主路升温速率过快、熬煮方法不恰当、试压试漏及堵漏不规范等6个方面分析石墨换热器大面积爆管的原因,并提出预防措施。     

Sulfur-free exfoliated graphite with large exfoliated volume: Preparation,characterization and its adsorption performance

Sulfur-free exfoliated graphite (EG) with large exfoliated volume (760 mL g⁻¹) was prepared through chemical oxidation, followed by microwave exfoliation. SEM results indicated that well-developed network pores in the worm-like structure of EG could be clearly observed. XPS results displayed that some functional groups were yielded on the surface of the as-prepared EG. Moreover, the capacity of EG was evaluated by the adsorption of rodamine B and 4-chlorophenol aqueous solution. Results showed that EG exhibited high adsorption capacity for RhB and 4-CP, which could be attributed to the functional groups and well-developed network pores in the worm-like EG.     

影响大型筒仓配煤精度的因素探讨

介绍了沙钢焦化厂大型筒仓的使用情况。导致配煤误差的原因主要是筒仓悬料、计量皮带称故障、称量皮带黏煤。对悬料的原因及采取的处理办法作了详细的介绍。     

A graphite foam reinforced by graphite particles

Graphite foam was obtained after carbonization and graphitization of a pitch foam formed by the pyrolysis of coal tar based mesophase pitch mixed with graphite particles in a high pressure and temperature chamber. The graphite foam possessed high mechanical strength and exceptional thermal conductivity after adding the graphite particles. Experimental results showed that the thermal conductivity of modified graphite foam reached 110 W/m K, and its compressive strength increased from 3.7 MPa to 12.5 MPa with the addition of 5 wt% graphite particles. Through the microscopic observation, it was also found that fewer micro-cracks were formed in the cell wall of the modified foam as compared with pure graphite foam. The graphitization degree of modified foam reached 84.9% and the ligament of graphite foam exhibited high alignment after carbonization at 1200 °C for 3 h and graphitization at 3000 °C for 10 min.