Effect of Binder and Additives on Properties of NdFeB Bonded Magnets by Injection Moulding

Properties of NdFeB bonded magnets by injection moulding lie on many factors. The study indicates that those such as coupling agents exterior covering, binder contents, antioxidant and the selection of lubricator have significant effects on the properties of NdFeB bonded magnets. The appropriate choice of additives can improve the properties of NdFeB bonded magnet.     

铁矿球团复合粘结剂的试验研究

针对有机粘结剂SN与膨润土复合而成的粘结剂,研究了其对球团生产指标的影响.试验结果表明:该复合粘结剂是一种成球性能良好的粘结剂,能有效地提高生球强度;同时,具有较好的抗爆裂性能,当复合粘结剂E、F添加量为08%,动爆温度由500 ℃升至700 ℃时,其生球无爆裂发生;而且它对成品球抗压强度的影响并不明显,可大大降低膨润土用量,提高球团矿品位.     

硬质合金粉末注射成形偏析现象的数值模拟

基于粉末-粘结剂的双流体模型,采用CFX商业软件对硬质合金粉末注射成形(PIM)过程进行了数值模拟,分析了充模过程产生的偏析现象.研究表明,PIM中的偏析有两类:一类是由于粉末与粘结剂密度及粘度的差异引起的普通偏析,密度的差异主要引起浇口附近粘结剂的轻微聚集,而粘度的差异引起允模前沿粘结剂体积分数的增加;另一类是由于边界层的存在及普通偏析共同作用形成的边界偏析,这种偏析使靠近模壁的粘结剂体积分数大于其平均值.局部密度测试证明了基于双流体模型模拟PIM过程偏析现象的可靠性.     

铁水喷吹脱硅及铁粉还原技术的开发及应用

利用混铁炉倒铁水的自然搅拌动能,将含铁粉剂喷入铁水中,脱除铁水中的部分Si。通过选择合理的系统参数,优化脱硅粉剂配比,调节下料速度在10kg/s以上,并开发了喷吹脱硅自动控制系统,下料量控制精度达到了1%,保证了脱硅反应的平稳进行,脱硅剂反应充分,脱硅量0.07%。     

铁水预处理喷粉操作实验研究

利用SL-250型喷粉装置实验研究了铁水预处理过程中的喷粉操作,并依据测定数据建立了喷粉操作参数之间的非线性回归方程。     

煤基铁精粉生产低硫珠铁试验研究

对采用铁精粉、煤粉和石灰石为主要原料,配加CaF2所制成的含碳球团,在不同试验方案下进行还原试验研究,分析珠铁的生产过程和渣铁的组织成分,计算硫元素的分配情况.试验结果表明:采用合理的试验方案,能使含碳球团在27 min内还原熔分效果良好,并得到含硫量较低的珠铁;所得珠铁的内部组织结构主要由珠光体和渗碳体组成;渣中以Ca2Mg(Si2O7)和Ca3Mg(SiO4)2为主,其它成分很少;增加CaF2配入量,使得进入珠铁中的硫元素减少,进入渣中的硫元素增多;提高加热温度,使得进入珠铁中的硫元素减少,进入空气中的硫元素增多.     

Development and Design of Binder Systems for Titanium Metal Injection Molding: An Overview

Titanium metal injection molding (Ti-MIM) has been practiced since the late 1980s. Logically, the Ti-MIM practice follows the similar processes developed for the antecedent materials such as stainless steel and ceramics. Although Ti-MIM is a favorite research topic today, the issue of convincing the designers to use Ti injection-molded parts still exists. This is mainly because of the concern about contamination which seems unavoidable during the Ti-MIM process. Much information about the binder formulation, powder requirements, debinding, and sintering is available in the literature. There are several powder vendors and feedstock suppliers. However, most of the binders in the feedstock are proprietarily protected. The disclosed information on the binders used for formulating powder feedstock is very limited, which in turn discourages their adoption by engineering designers. This overview intends to discuss some of major binder systems for Ti-MIM available in the literature. It serves to provide a guideline for the Ti-MIM practitioners to choose a suitable powder feedstock.     

IR喷吹硅钙粉脱硫试验研究

在深入分析SiCa粉脱硫热力学及动力学基础上，进行了50多次的钢包IR喷次SiCa粉深脱硫工艺试验，确定了喷吹精炼最佳方案及操作工艺参数，对指导大生产起着重要作用。     

昆钢高炉铁水成分对转炉炼钢工序的影响

通过2000年1－4月份昆钢高炉铁水成分对转炉炼钢石灰消耗量影响的统计计算，得到统计经验公式为：Ws=7.57Si% 8.106P% 0.535。为进一步降低炼钢成本、科学管理生产提供了依据。     

Effect of Nanopowder Addition on the Sintering of Water-Atomized Iron Powder

Metallurgical and Materials Transactions A - A promising method of improving the densification of powder metallurgical steel components is to blend nanopowder with the otherwise typically used...     

铁矿粉流化床直接还原防止粘结的试验研究

研究了流化床铁矿粉直接还原过程中掺入惰性物质对防止粘结的效果以及粘结失流与铁矿的组成、粒度、还原温度、还原气氛、金属化率、掺入惰性物质种类、数量等多种因素的关系,探讨了粘结失流机理。结果表明:MgO是最有效的防止粘接添加剂,使用量小于5%;CaO次之,使用量约为5%～10%。少量焦粉、白云石、碳酸钙等对抑制粘结失流无明显的作用。铁矿的熔点越低、粒度越小、金属化率越高、温度越高就越容易失流。     

基于线性规划算法的磷生铁最优化成分设计

铝电解槽阳极组装用磷生铁在使用过程中需要的特性与其本体材料的物理性能息息相关。运用材料热力学的方法计算出五大元素(C,Si,P,Mn,S)的含量变化对磷生铁电导率和热膨胀系数的影响,并通过线性回归建立电导率和热膨胀系数与五大元素含量和温度的函数关系,最后利用线性规划最优化算法对某铝厂现行磷生铁成分进行有目的性的优化。通过优化后,磷生铁电导率最大优化率为14.50%,热膨胀系数最大优化率为5.99%。     

Properties of Anisotropic Nd(Fe,Co)B Type Sintered Magnets Produced by Powder Injection Moulding

Abstract

Anisotropic Nd(Fe,Co)B type sintered permanent magnets were fabricated by powder injection moulding (PIM) using paraffin wax as a binder. A conventional process was also used in order to compare the resultant properties with those of sintered magnets produced by PIM. Magnetic properties, microstructure, and constituents were investigated by dc fluxmeter, scanning electron microscopy, X-ray diffractometry, wavelength dispersive X-ray analysis, and ir absorption analysis. Effects of particle alignment of the sintered magnets on the magnetic properties and anisometric linear shrinkage ratios were studied. Particle alignment of sintered magnets produced by PIM was 4% lower than that of the conventional process. The PIM sintered magnet exhibited a maximum energy product of 232 kJ m^?3. The residual carbon after debinding affected the magnetic properties and sintering characteristics by contaminating the liquid phase during PIM sintering. PM/0782     

粘结剂对程潮铁精矿球团质量的影响

研究了程潮铁矿球团原料条件下,配加膨润土、有机粘结剂一羧甲基纤维素钠(CMC)、以及二者的复后粘结剂对球团生产及球团矿质量的影响.结果表明,在1.5％膨润土+0.05％羧甲基纤维素钠(CMC)复合的条件下,取得了良好的试验效果,生球落下强度＞6次/个,抗压强度＞10 N/个,爆裂温度＞ 600℃,成品球抗压强度＞2 5...     

脉石成分对铁矿球团还原膨胀性能的影响

研究了脉石成分对铁矿球团还原膨胀性能的影响.以纯铁矿物为原料采用压块-焙烧-还原方法进行的研究表明:纯赤铁矿团块的还原膨胀率明显大于纯磁铁矿团块;CaO、SiO2、MgO、Al2O3可显著降低赤铁矿团块的还原膨胀率;SiO2、MgO可在一定程度上降低磁铁矿团块还原膨胀率,CaO、Al2O3则使磁铁矿团块的还原膨胀率增大.在此基础上研究了赤铁精矿为主配加磁铁精矿制备的氧化球团矿的还原膨胀性能,确定了抑制球团矿还原膨胀的适宜添加物及其用量.对CaO导致球团异常膨胀的机理进行了探讨:在浮氏体还原成金属铁的过程中,固溶于铁氧化物晶格中的Ca2 会促进"铁晶须"的生成与发展,导致球团产生异常膨胀.     

钢包密闭喷粉脱硫脱氮的工业试验研究

通过在18t钢包上进行的钢包密闭喷粉脱硫脱氮新工艺的试验表明：该工艺在脱硫的同时，能脱除部分钢中氮。验证了在250kg感应炉上的试验结果，为寻求钢液低成本脱硫脱氮方法提供了思路。     

Effects of Binder on the Properties of Iron Ore-Coal Composite Pellets

Large amounts of fines and superfines are generated in Indian iron ore and coal mines due to mechanized mining and mineral dressing operations. Utilization of these fines for extracting metal is of vital concern for resource utilization and pollution control. For agglomeration of these fines, a suitable binder is required. Iron ore-coal composite pellets were prepared by cold bonding. Various binders such as lime, Ca(OH)₂, slaked lime, dextrose, molasses, and sodium polyacrylate (SPA), alone or in combination, were employed for making composite briquettes. The slaked lime–dextrose combination produced the highest strength among the various binders employed for producing composite briquettes and was therefore selected for producing composite pellets for the smelting reduction. In cold bonding, the composite pellets attain the requisite properties due to physico-chemical changes of the binder in ambient conditions. It was possible to obtain a dry strength of more than 300 N per pellet in some cases and more than 200 N per pellet in many trials. Drop strength and shatter index values of composite pellets were also measured. In the present paper an attempt has been made to evaluate the mechanical properties of cold-bonded composite pellets so as to throw some light on the capacity of these pellets to withstand stresses during handling and transportation.     

Effect of Hydrogen Heat Treatment on the Chemical Composition of Aluminum Nitride Powder

The effect of hydrogen heat treatment on impurity contents in aluminum nitride powder of different fineness is studied. Thermodynamic calculations are provided pointing to the possibility of forming gaseous hydrogen compounds with impurity elements. It is established that as a result of treatment the contents of impurity elements, i.e. oxygen, carbon, sulfur, are reduced by a factor of 3-13. The optimum hydrogen heat treatment regime is determined: a temperature of 1323 K and an exposure time of 30 min.