电渣精炼去除工业纯铝中杂质Fe的研究

研究了添加Na_2B_4O_7的KCl-NaCl-Na_3AlF_6混合渣剂电渣精炼去除工业纯铝中杂质Fe的效果。研究发现,工业纯铝中的Fe含量随着电渣重熔速率的降低而不断减少,当重熔速率为180g·min~(-1)时,电渣精炼除Fe效果最好,Fe含量从电渣精炼前的0.42%减少到0.20%,杂质Fe的去除率超过50%。Fe含量的降低是因为熔融渣剂捕获了Al熔体与熔融渣剂反应生成的富Fe中间化合物Fe_2B。电渣精炼除Fe反应的热力学计算表明渣剂中的Na_2B_4O_7能与Al熔体中的杂质Fe自发反应生成中间化合物Fe_2B。电渣精炼除Fe后工业纯铝的抗拉强度和伸长率随着Fe含量的降低得到明显改善。     

电渣精炼去除铝中夹杂物的研究

采用电渣精炼法去除工业纯铝中的夹杂物,研究了电渣精炼去除夹杂物的效果及机理。结果表明,工业纯铝中夹杂物的去除效率随着电渣重熔速率的减小不断提高;当电渣重熔速率为108g·min~(-1)时,夹杂物的去除效果最佳,达到97.6%。在电渣精炼过程中,工业纯铝中的夹杂物被熔融渣剂所捕获。夹杂物-铝熔体-熔融渣剂体系的吉布斯自由能计算结果表明,在铝熔滴中的夹杂物具有从铝熔体中自发迁移到熔融渣剂中的趋势。     

Na2B4O7对再生铝合金除铁效果的影响

采用电感耦合等离子体原子发射光谱仪、金相显微镜等手段研究不同Na2B4O7添加量、反应温度及保温时间对再生铝合金的除铁效果的影响,利用阿基米德原理间接得到在不同温度下Na2B4O7不同的添加量对气孔率的影响.结果表明:在720℃温度下添加0.5％的Na2B4O7、保温30 min除铁率达到最大值7.57％.680℃和760℃温度下随着Na2B4O7添加量的提高导致试样内部气孔的增多而密度均在递减,在720℃下添加量为0.5％时试样密度在增大甚至达到2.69 g/cm3,超出无添加时达到3.46％.适宜的除铁工艺为:Na2B4O7添加量为0.5％,处理温度720℃,保温时间30 min.     

真空-还原精炼法制备低氧高钛铁合金

针对铝热还原法制备的高钛铁中O含量高、夹杂多等缺点,提出了以铝热法高钛铁为原料进行真空还原精炼制备低O高钛铁的新思路。研究了精炼温度、精炼渣等因素对精炼效果的影响,采用XRD、SEM及化学元素分析等手段对高钛铁合金进行了研究。结果表明,合适的精炼渣和较高的精炼温度对保证精炼效果十分重要;还原精炼后合金的微观结构均匀致密,夹杂物得到有效去除,O含量显著降低;2000℃时以CaO-Al2O3为精炼渣制备的高钛铁合金中钛含量为69.80%,铁含量为22.55%,铝含量为2.58%,硅含量为2.02%,O含量为2.60%,符合优质高钛铁合金的技术要求。     

渗硼用Na2B4O7-Na2CO3熔盐热分析

对渗硼用Na2B4O7-Na2CO3熔盐体系进行DTA和TG热分析。DTA分析表明,在Na2B4O7中添加Na2CO3并没有大幅降低Na2B4O7的初晶温度。TG分析表明,Na2B4O7中添加Na2CO3能促进Na2B4O7的分解,平均每添加10%Na2CO3体系质量损失4%。Na2B4O7-Na2CO3体系的温度升高过程分别对应固体Na2B4O7的分解、渗剂熔化以及B2O2的氧化过程。硼砂熔盐渗硼最佳温度为905℃。     

CaO-Al2O3基精炼渣添加BaO等组分对硫分配比的影响

采用二次正交回归方法设计了以CaO-Al2O3为基,添加MgO、BaO、CaF2、Na2O等组分的精炼渣,通过实验室系统研究,建立了硫分配比与精炼渣组分百分比含量关系的数学模型;确定了脱硫精炼渣的最佳组成。采用该精炼渣进行脱硫试验,可使钢中硫含量降至0.0004%。     

CaO-A12O3基精炼渣添加BaO等组分对硫分配比的影响

采用二次正交回归方法设计了以CaO-A12O3为基,添加MgO、BaO、CaF2、Na2O等组分的精炼渣,通过实验室系统研究,建立了硫分配比与精炼渣组分百分比含量关系的数学模型;确定了脱硫精炼渣的最佳组成.采用该精炼渣进行脱硫试验,可使钢中硫含量降至0.0004%.     

控制低铝的电渣重熔技术研究

上海重型机器厂开发了控制低铝(≤0.010%)的电渣重熔技术。报导了6t(30Cr1Mo1V)、6.5t(60CrMnMo)、4.5t(2.25Cr-1Mo)和90t(26Cr2Ni4MoV)、95t(26Cr2Ni4MoV)、100t(30Cr1Mo1V)电渣重熔锭的试验研究和试生产应用结果。在自耗电极中的铝低达0.006%的情况下,重熔金属的铝为0.003%,[O]=20ppm,[S]=0.0011%。在电极铝被大量氧化的情况下,硅锰可受到保护不烧损。200t 级电渣重熔炉长达数十小时的重熔过程中,金属熔池中的铝稳定地保持在0.006～0.008%范围,相应的氧含量为25ppm,硫含量为0.0020%。低铝、低氧、低硫在锭高方向上分布均匀。90t、95t,100t 电渣锭重熔过程中金属熔池中的氢含量始终为2 ppm。三根大型电渣锭已生产成大锻件,产品质量优良。     

铬铁矿中杂质铝和铁对铬氧化率的影响及其机理

以实验室合成的尖晶石型化合物为原料,系统地研究铬铁矿无钙焙烧体系中杂质铁和铝对Cr(Ⅲ)氧化率的影响规律及其机理。结果表明:铬铁矿中杂质铁对Cr(Ⅲ)的氧化率无明显影响;焙烧过程中FeO被氧化后得到的Fe2O3先与Na2CO3反应生成中间产物NaFeO2,它在体系中仍能起着Na2CO3的作用,使铬的氧化反应继续进行,整个Cr(Ⅲ)氧化过程的反应速率均较快;而杂质铝能明显抑制Cr(Ⅲ)的氧化,其主要原因是:在焙烧过程中,Al2O3与Cr2O3和MgO反应生成相对稳定、难溶的多元复杂氧化物MgO·(Cr2O3)0.5.(Al2O3)0.5。此外,Al2O3与Na2CO3反应生成Na2O·Al2O3,但Na2O·Al2O3很难进一步与MgO.(Cr2O3)0.5·(Al2O3)0.5反应生成Na2CrO4。     

高铝粉煤灰预脱硅碱石灰烧结法提铝硅钙渣脱碱工艺研究

高铝粉煤灰预脱硅碱石灰烧结法提取氧化铝过程中产生一定量的硅钙渣,所产硅钙渣中Ca O、Si O2含量与传统烧结法赤泥相比含量更高,更易于用于水泥行业。本文在对两种提铝残渣进行区别研究的基础上,研究了采用石灰乳对硅钙渣进行脱碱的不同工艺条件,研究表明:采用Ca Of添加量为硅钙渣量的10%,脱碱时间3小时能够将硅钙渣中的氧化钠降低到1.00%以下,从而大大提高硅钙渣在建材制备过程中的添加量。     

ZYP40R塑料模具钢电渣重熔工艺实践

介绍了 ZYP40R模具钢的电渣重熔生产工艺.通过电极坯母材原始铝含量控制、电渣重熔时采用返回渣系、重熔过程脱氧剂分阶段加入、全程氩气保护等方式有效保证电渣钢中的铝含量,生产出符合要求的自耗电极及电渣锭.     

Processing of high carbon Fe3Al based intermetallic alloy

A melting procedure for air induction melting (AIM) of an Fe₃Al based intermetallic alloy Fe-15.38 wt%Al-1.1 wt%C is described. Use of an appropriate slag cover during AIM results in elimination of hydrogen gas porosity in cast AIM ingots. Criteria for slag selection and slag to metal ratio are discussed. Refining by slag-metal reactions results in significant reduction in impurity levels (S, O, N) during AIM. Consequently, low cost raw materials such as mild steel scrap and commercial aluminium were used for melting the alloy. The AIM ingot exhibited excellent tensile properties. The ductility and hot workability of the ingot may be further improved by subsequent processing through electroslag remelting. It is also argued that the presence of carbon may be necessary to get AIM castings with desirable mechanical properties.     

高温镍基合金电渣重熔过程中的Al、Ti成分控制

电渣重熔过程中Al和Ti的氧化导致电渣锭轴向成分不均匀,从而对电渣锭的耐腐蚀性能和力学性能产生不利影响。为了控制电渣铸锭中Al和Ti含量的均匀性,需要明确高温电渣重熔过程中Al和Ti含量的变化,并通过优化渣体系比例和冶炼条件来减少合金中Al和Ti的氧化。在现有文献的基础上,以CaF₂-CaO-Al₂O₃-MgO-TiO₂这一低氟渣系和Incoloy825合金为例,综述了电渣重熔过程中Al和Ti元素控制的研究现状。应用离子与分子共存理论（IMCT）,结合FactSage软件,总结了渣的热力学和动力学研究方法。讨论了温度和渣成分对合金中平衡Al、Ti含量的影响。基于膜渗透理论,提出了预测合金中Al和Ti含量的动力学模型,得到了电渣过程中Al和Ti含量随时间变化的数学方程式以及渣-金属反应速率的限制方法。确定电渣重熔Incoloy825合金时TiO₂的最佳添加量约为10％。用IMCT和FactSage对渣-金平衡实验结果进行了比较和分析。FactSage计算结果比IMCT计算结果更准确。TiO₂含量越高,计算结果与实验结果之间的偏差越小。     

Oxidization mechanism in CaO-FeOx-SiO2 slag with high iron content

Oxidization mechanism in CaO-FeOx-SiO2 slag with high iron content was investigated by blowing oxygen into molten slag so as to oxidize Fe（ Ⅱ）. The relationship between Fe（ Ⅱ ） content and oxidizing time at different temperatures was obtained by chemical analysis. Microstructure of slag was observed by metallographic microscope and SEM. Phases compositions were ascertained by EDXS and XRD. Grain size and crystallizing quantity of magnetite（Fe3O4 ） were determined by image analyzer. The oxidizing kinetic equations were deduced. Confirmed by graphical construction method, Fe（ Ⅱ ） oxidizing reaction in CaO-FeOx-SiO2 slag system is of first order, and the reaction apparent energy Eo is 296. 67 kJ/mol in the pure oxygen and 340. 30 kJ/mol in air. The enrichment and crystal growth mechanism of magnetite（Fe3O4 ） phases were investigated. In oxidizing process, content of fayalite declines, while that of magnetite（Fe3O4 ） increases, and iron resources enrich into magnetite（Fe3O4 ） phase. All these provide a theoretical base for compressive utilizing of those slags.     

电渣重熔对TiC强化2Cr13不锈钢力学性能和断口的影响

在2Cr13不锈钢中引入TiC颗粒后,室温强度有大幅提高,但塑性和冲击韧性却发生了较大幅度的下降．原位合成的TiC颗粒,尺寸较大且有轻微团聚现象,导致了在拉伸和冲击过程中颗粒易破碎,断裂机制是以TiC增强体失效为主;对TiC强化2Cr13进行电渣重熔后,综合性能得到了改善,TiC颗粒变小且分布变均匀,在拉伸和冲击过程中颗粒不易破碎,断裂机制是以TiC与基体的界面失效为主．     

涡流贫化法回收铜渣中的金、银、铜

采用熔融铜渣为原料,经过涡流贫化过程,回收铜渣中的金、银、铜,贫化渣进一步升温还原得到含铜铁水,最终可制备成耐磨铸铁。结果表明,通过涡流贫化,铜渣中的Fe_3O_4被还原为FeO,然后FeO与SiO_2结合,生成Fe_2SiO_4。经过涡流贫化后,金、银、铜的回收率分别达到了99.44%、93.97%和93.14%。贫化渣中Fe_3O_4和铜的含量分别为1.53%和0.61%(质量分数)。贫化渣涡流还原后得到的含铜铁水制备的耐磨铸铁成分满足高铬耐磨铸铁国标要求。     

Effect of Ilmenite Component and AIR on Element Distribution of Titanium Slag Smelted by DC Arc Furnace

助化学平衡计算法,对冶炼过程中钛、碳及伴生元素的分配行为进行了研究,并用生产结果加以验证,计算结果与实验结果较吻合。结果表明:钛铁矿中Ti O2和Fe O含量的增加,增加了作为微量元素和用于还原Fe O和Ti O2的C量,提高了钛渣中总的Ti O2和Ti2O3的量,同时降低了用于还原Fe2O3的C量,降低了钛渣中Fe O的含量。当钛渣中Fe2O3含量由12%增加到20%时,作为微量元素C和用于还原Fe2O3的C量分别降低了0.006 mol和0.348 mol,钛渣中总的Ti O2和Ti2O3的量分别降低了8.34%和2.37%,而用于还原Fe2O3的C量增加了约0.36 mol,Fe O的质量分数增加了8.94%。其他成分对钛渣中总的Ti O2量的影响程度由大到小排序为:Si O2>Mg O>Al2O3>Ca O。对钛渣还原冶炼过程中元素分配行为的研究,可实现对工艺的更好控制、提高钛渣品位。     

Fe对稀土电工铝导线性能的影响

探究了Fe元素对稀土电工铝导线性能的影响,测试了合金的抗拉强度、伸长率及导电率。研究结果表明,Fe元素能够显著提高铝导线的抗拉强度和伸长率,但随Fe元素含量增高,其对铝导线导电率的降低作用越明显。综合抗拉强度、伸长率及导电率的检测结果,W（Fe）=0．3％时,合金的力学性能和导电性能较好。     

Grain Refining Efficiency of SHS Al-Ti-B-C Master Alloy for Pure Aluminum and Its Effect on Mechanical Properties

A new Al-5Ti-0.75B-0.2C master alloy was successfully prepared by self-propagating high-temperature(SHS)reaction from an Al-Ti-B_4C system with molten Al.Microstructure and phase characterization of the prepared Al-5Ti-0.75B-0.2C master alloy show that the nearly spherical TiC particles,hexagonal or rectangular TiB_2 particles,and blocklike TiAl_3 particles distribute uniformly in the aluminum matrix.Grain refining test on commercial pure aluminum indicates that Al-5Ti-0.75B-0.2C master alloy exhibits a better grain refining performance than Al-5Ti-lB master alloy.By addition of 0.2 wt%Al-5Ti-0.75B-0.2C master alloy,the average grain size of a-Al can be effectively refined to160 ± 5 μm from about 3000 μm,and the tensile strength and elongation are increased by about 20%and 14.1%due to the grain refinement.     

Factors influencing power consumption and power-saving measures in ESR process

Since the USA patent of electroslag remelting(ESR) metallurgy was held by P. K. Hopkins in 1940, the ESR technology has now entered a relatively mature stage after a 70-year history of development. At present, the annual capacity of ESR steels around the world is approximately 2 million tonnes. ESR metallurgy emerged in China in 1958. Since then, electroslag furnaces were gradually installed in Chinese special steel plants. At present, there are more than 200 electroslag remelting furnaces in the metallurgical workshops of these steel plants with an annual production capacity of about 500,000 tonnes of ingots and components made of about 200 varieties of steels, including high quality steels and superalloys. This ESR technology is used as a special remelting and refining method for producing high quality steels and superalloys. However, traditional ESR technology has the disadvantages of environmental pollution and extremely high specific power consumption. High power consumption restricts, to a certain degree, the competitiveness of ESR steels in the marketplace. The measures of power saving in ESR have been researched in recent years. In this paper, some factors influencing power consumption, such as filling ratio, slag system, slag amount, melting rate and furnace structure are reviewed, and several new ESR technologies for power saving are proposed.