硼铁矿冶炼Fe－Si－B合金的工艺研究

建立了以辽东硼铁矿为原料，用碳热还原成碳－铝热还原冶炼Ｆｅ－Ｓｉ－Ｂ合金的工艺，测定了还原时间和温度对合金中Ｂ，Ｓｉ，Ｃ含量的影响以及Ｃ含量与Ｂ和Ｂｉ含量的关系：用熔渣－金属平衡方法对合金进行脱Ａｌ，研究了碱度以及Ｂ２Ｏ３和ＳｉＯ２含量对合金中Ａｌ含量的影响．结果表明，该工艺可使合金中Ｃ含量降至０．１５％，Ａｌ含量小于０．０５％．     

钒铁冶炼炉氧化铝渣的性能分析

为了探索钒铁冶炼炉氧化铝渣用于耐火材料的可能性,选取完整的氧化铝渣渣饼,剖开后根据其断面不同区域的颜色和致密度分层取样,检测其理化性能、物相组成、颗粒(5~3 mm)强度及水硬特性。试验结果表明:氧化铝渣饼大致可分为三层:以MgO为主要成分(质量分数为83.89%)的镁砂层,以镁铝尖晶石、方镁石和二铝酸一钙为主晶相的变质层,以二铝酸一钙和镁铝尖晶石为主晶相(二者的体积分数之和在80%以上)的主渣层;各渣层的耐火度大于1 790℃,体积密度大于3.0 g·cm-3,吸水率≤2.4%;主渣层的颗粒强度与焦宝石的接近,具有水硬性。综合来看,氧化铝渣可用于耐火材料。     

钛、钨氧化物碳热还原-碳化的热力学和热分析

为了研究采用TiO₂、WO_2.72和炭黑粉末为原料,在惰性气氛下通过碳热还原-碳化制备(Ti,W)C固溶体的过程机理,采用HSC Chemistry热力学分析软件、热重和差示扫描量热分析方法,对物相的演变过程进行分析。结果表明,因球磨导致原料反应活性升高、气-固反应共存等,实际的反应起始温度低于热力学计算值。随温度升高,TiO₂和WO_2.72分别按TiO₂→Ti₄O₇→Ti₃O₅→Ti2O₃→TiO→TiC和WO_2.72→WO₂→W→W₂C→WC的转变顺序被还原并碳化。为了加速反应的动力学进程,通过碳热还原-碳化制备(Ti,W)C固溶体的最终温度应在1400℃以上。     

反应物量对纳米晶Fe_3Al组织和性能的影响

利用铝热反应熔化方法分别在反应物量为50、100、200g的条件下制备了块体纳米晶Fe3Al材料,通过TEM和XRD研究了材料的晶粒尺寸,并研究了材料室温压缩性能和硬度。结果表明,所制备的材料主要由非晶和纳米晶组织组成,当反应物量增大,部分区域甚至出现微米晶组织。反应物量为50g时Fe3Al材料中非晶较多,不存在微米晶;反应物量为100g时主要以纳米晶为主,非晶数量减少,伴随有少量的微米晶出现;反应物量为200g时,材料以纳米晶为主,微米晶数量较100g时有所增加。随着反应物量的增加,纳米晶相的平均晶粒尺寸增加,屈服强度和硬度呈先增大后减小的趋势。     

铝对自蔓延火焰淬熄法合成空心陶瓷微珠的影响

以自蔓延高温合成技术(SHS)为基础,采用自反应淬熄法研究TiO2+蔗糖,TiO2+蔗糖+Al两种体系下空心陶瓷微珠的反应生成情况。以SEM、XRD、EDS为手段分别测试所得产物的形貌、主要相组成以及微区成分组成。结果表明:TiO2+蔗糖体系所得产物由不规则的块状物质与表面凹凸不平的类球形物质组成;TiO2+蔗糖+Al体系熔射产物全部由表面光滑的球形颗粒组成。球形颗粒为空心结构,主要组成为Al2O3-TiC复相和少量的铝钛合金、AlN以及Ti(C,N)。Al的加入大大改善了空心微珠的生成。     

The Effect of Excess Aluminum on the Composition and Microstructure of Nb-Al Alloys Produced by Aluminothermic Reduction of Nb2O5

Intermetallic aluminides including those phases of the Nb-Al system are of interest for high-temperature structural applications. Through aluminothermic reduction (ATR) of Nb₂O₅ different alloys of the Nb-Al system can be produced by varying the amount of aluminum (excess aluminum) in the thermit charge. In this work, various Nb-Al alloys were produced by varying Nb₂O₅ and Al powder blends. The resulting alloys were characterized by chemical analysis (Al, O, and C), X-ray diffraction and scanning electron microscopy. The aluminum content of the alloys increased linearly from 14.5 to 50.4 at% as the excess Al was varied from 10 up to 60% over the stoichiometric amount to reduce the Nb₂O₅. The carbon content was lower than 300 wt-ppm. The oxygen content decreases with increasing excess Al, reaching 1300 wt-ppm for the alloy produced with 60% excess Al. The inclusion content (Al₂O₃) decreases significantly as the excess Al is increased. The following metallic phases were identified in the alloys: Nb_ss (niobium solid solution) and Nb₃Al (alloy produced with 10% excess Al); Nb₃Al (alloys produced with 15 and 20% excess Al); Nb₃Al, Nb₂Al, and NbAl₃ (alloy produced with 30% excess Al); and Nb₂Al and NbAl₃ (alloys produced with 40, 50, and 60% excess Al).     

不同底材对亚微米亚共晶白口铸铁组织和力学性能的影响

通过铝热反应法分别在铜底材和玻璃底材上制备了亚微米亚共晶铸铁。利用光学显微镜、扫描电镜、X射线衍射仪及电子探针对亚共晶铸铁的组织及成分进行了研究。测试了亚共晶铸铁的硬度、压缩性能和拉伸性能。结果表明:该方法制备的亚共晶铸铁是由渗碳体以及珠光体组成,铜底材和玻璃底材亚共晶铸铁的平均珠光体层间距分别为220nm和165nm。铜底材和玻璃底材亚共晶白口铁的维氏硬度分别为564HV和552HV,抗压强度分别为2429MPa和2224MPa,抗拉强度分别为391MPa和383MPa,伸长率分别为2%和3%。     

In situ TiC-reinforced austenitic steel composite by self-propagating high temperature synthesis

TiC-reinforced austenitic steel composites have been prepared by self-propagating high temperature synthesis (SHS). The in situ reinforcement of a Fe-Mn-based austenitic steel matrix with TiC was achieved upon aluminothermic reduction of iron oxide (Fe₂O₃), manganese dioxide (MnO₂) and titanium dioxide (TiO₂) powders in the presence of carbon (C). This highly exothermic thermite reaction was found to produce in situ the Fe-Mn-TiC austenitic steel composites. The reaction kinetics, recovery of Mn and TiC, yield of metal, and composite microstructure were found to strongly depend on the process parameters, such as green composition, blending sequence, and average particle size of Al powder used as a reducing agent. The text was submitted by the authors in English.     

Synthesis of nano (Ti,W)C powder with preferred orientation and twin boundary structure

(Ti,W)C is a novel additive for high performance cermets. In this study, (Ti_0.88W_0.12)C with the lowest formation energy is synthesized by carbothermal reduction-carbonization in Ar. The starting materials included WO_2.72 with one-dimensional nanostructure, TiO₂ and carbon black. The phase transition temperatures were established by thermal analysis. XRD analysis results disclose that once TiC is formed at a temperature over 1220 °C, W atoms begin to diffuse into the TiC lattices, which is independent of the existing form of tungsten. At a condition of 1500 °C for 180 min, W and C atoms from the decomposed W₂C and WC are fully dissolved in the TiC lattices. Under such a TiC-centered atomic reconfiguration environment, the as-synthesized powder is featured with a BET particle size of 76 nm and texture coefficients TC₍₁₁₁₎ of 1.53 and TC₍₂₀₀₎ of 1.33. Results from SEM and HRTEM reveal that the roughly equiaxed powder particles have characteristics of readily identified twin boundary structure and stacking faults. Microscopic inhomogeneity of W solution atoms is discussed. The revelation of the easily identified twin boundary structure and stacking faults is of great significance to the hard phase regulation for high performance Ti(C,N)-based cermets.     

铜包快速焊补技术

铜冶炼厂盛冰铜的钢包经常被冰铜侵蚀．要修补一个中等部位需耗费大量人力和费用，而且劳动条件十分恶劣，用铝热焊修补金属量为１００ｋｇ的凹坑，全部工作仅需３０ｍｉｎ，节约了大量的人力和物力，是一种值得推广的方法．