电场作用下Fe含量对Fe-Ti-C体系低温燃烧合成的影响

采用Gleeble-15001)热模拟机，对电场作用下Fe含量对Fe-Ti-C体系低温燃烧合成过程和产物显微结构特征的影响进行了研究。结果表明：在电场和大热流密度作用下，体系的点火温度可以大幅降低；Fe含量越高，其对体系低温燃烧合成过程的影响越大。随Fe含量增加，体系点火温度升高，点火延迟时间缩短，所达到的最高温度也升高；与高温燃烧合成类似，低温燃烧合成的产物由TiC，Fe，少量Fe2Ti组成；当Fe含量为45％时(质量百分数，下同)，产物中的TiC量最多，且颗粒细小。     

Ti3AlC2与Fe在高温下的反应行为（英文）

通过TG-DTA、XRD、SEM和EDS的分析,研究Ti3AlC2与Fe在高温下的互相反应。结果表明,当烧结温度在659.9℃以上时,Ti3AlC2与Fe主要以放热反应为主,当烧结温度为760~1045℃时,Ti3AlC2与Fe之间的反应较弱,并开始生成TiC0.625相;随着烧结温度升到1045℃时,Ti3AlC2的衍射峰逐渐消失,烧结产物的衍射峰只有TiC0.625和Fe(Al)固溶体;随着温度的进一步升高,烧结产物的衍射峰基本为TiC0.625和Fe(Al)固溶体不变。采用SEM和EDS分析可知,该反应主要发生了两个过程,其一,Ti3AlC2发生了分解,Ti3AlC2中的Al发生了析出,并固溶到基体的金属相中形成Fe(Al)固溶体,而Ti3AlC2中Ti和C则形成了TiC0.625陶瓷相。其二,Fe原子沿着Ti3AlC2分解形成的Al空位渗入到Ti3AlC2颗粒中,进而导致Ti3AlC2进一步分解成粒径更小颗粒。Ti3AlC2中Al的析出是导致Ti3AlC2在远低于其分解温度下就与Fe发生反应的主要因素。     

反应火焰喷涂TiC/Fe复合涂层的动力学

以钛铁、铁和石墨为主要原料,用反应火焰喷涂技术制备TiC/Fe复合涂层。在喷涂过程中,在氧乙炔火焰条件下引燃Fe-Ti-C体系的自蔓延高温合成(SHS)反应,研究该SHS反应的动力学。结果表明,适当增加铁和石墨,或减小反应组元的粒度,会显著降低体系的点火温度,可促进Fe-Ti-C反应体系在氧乙炔火焰中的点火进程。喷涂粉末粒度、氧乙炔火焰功率、喷涂距离以及喷涂粉末的原料配比均会影响Ti-C间的反应程度,从而影响Fe-Ti-C体系的反应动力学。     

Study of formation behavior of ZrC in the Fe-Zr-C system during combustion synthesis

ZrC particles were prepared in situ by self-propagating high-temperature synthesis (SHS) reaction with the Fe-Zr-C elemental powder mixtures. The reaction behavior and formation route for synthesizing ZrC in the Fe-Zr-C system were investigated. With increasing Fe contents, the adiabatic temperatures, reaction temperatures and ZrC particles sizes were obviously decreased. Fe plays an important role in controlling the reaction behavior and morphology of products, Fe not only inhibits ZrC particle from growing, but also promotes the SHS reaction. The addition of Fe to Zr-C reactants promotes the ZrC-forming reaction.     

浸渗法制备高铬铸铁/TiC-SiC复合材料及微观组织

采用小颗粒TiC包覆SiC陶瓷颗粒,在惰性气体保护下选用无压浸渗方法制备了高铬铸铁/TiC-SiC复合材料;利用SEM/EDX观察和分析了液态铸铁在SiC预制体中的浸渗情况、组织特征和成分分布;结合高铬铸铁/Ti-SiC复合材料的组织特点和浸渗行为特点,分析了TiC粉体对浸渗行为和复合材料组织的影响。观察结果表明,当TiC加入量≤10%(质量分数,下同)时,Fe/Cr合金无法润湿SiC颗粒,而当加入量≥20%时,Fe/Cr合金和预制体之间润湿性得到改善,增加TiC含量更有利于Fe/Cr合金浸渗;基体中大尺寸SiC颗粒消失,出现了尺寸接近毫米级的条状单质碳,这与高铬铸铁/Ti-SiC复合材料的组织差异较大。对比两种复合材料组织发现,添加Ti粉末在金属液中可与C结合生成TiC,而添加的TiC颗粒在组织中呈鹅卵石状,边缘圆润,出现金属液与陶瓷颗粒之间的互溶。在浸渗过程中,添加TiC和Ti与浸渗金属发生的反应不同,且高质量分数的TiC对金属液浸渗过程有明显的促进作用。     

In-situ production and microstructures of iron aluminide/TiC composites

In this study we have tried to produce the titanium carbide reinforced iron aluminide composites by in-situ reaction between titanium and carbon in liquid iron–aluminum alloy doped with titanium and carbon. A homogeneous distribution of titanium carbide particles in the iron aluminide matrix up to about 16 vol% of titanium carbide was intended without agglomeration. The composition of TiC formed during in-situ reaction was investigated by ICP analysis and the Combustion-Infrared Absorption method after chemical dissolution of the iron aluminide matrix. It is found that the composition of titanium carbide formed during melt processing is an average of Ti–48.4 mol% C. In addition, titanium carbide has very low solubility of Fe and Al. The microstructure of composites consists of three different regions; primary large TiC particles of 5–40 μm, matrix with small dendritic TiC particles of about 1 μm and particle-free regions around primary large TiC particles. The formation of this complex microstructure can be explained by assuming the Fe₃Al–TiC pseudo-binary system containing the eutectic reaction. Particle-free regions are halos of iron aluminide phase and the formation of halos is explained by coupled zone concept. Subsequent heat treatment at 1373 K for 48 h induces spheroidization and/or coarsening of small TiC particles, while microstructure after heat treatment at 973 K for 48 h exhibits the additional formation of small TiC precipitates. Though excess 1 mol% Ti addition over the Ti content for TiC formation is soluble to Fe–28 mol% Al, excess 1 mol% C addition forms the secondary Fe₃AlC phase during melt processing.     

Effects of technological parameters on microstructures and properties of in situ TiC_p/Fe composites

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Controlling conditions for synthesis of iron-titanium carbide using two different titanium precursors

Preparation of Fe–TiC composite from mixtures of carbon black and two different titanium bearing minerals (black sand ilmenite and natural rutile) was studied. Milled (mechanically activated) and unmilled carbon containing mixtures were prepared and then heated at temperatures 1200 °C and 1300 °C for 3 h under an inert atmosphere. The reaction progress, as well as reaction products, was evaluated using thermogravimetric analysis (TGA-DTA), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and energy dispersive X-ray spectroscopy (EDX). The feasibility of producing Fe–TiC composites from titanium bearing materials mixed with carbon black was proved. Fe–TiC could be produced by carbothermic reduction of mechanically activated black sand ilmenite containing mixtures milled for 50 h and heated up to 1200 °C. On the other hand, 60 h milling followed by heating up to 1300 °C was needed in case of natural rutile containing mixture. The morphology of the Fe–TiC produced from black sand ilmenite showed a homogeneous distribution of Fe and TiC enriched areas, while the Fe–TiC produced from natural rutile showed intense distribution of TiC phase with traces of iron and lower titanium oxide.     

反应火焰喷涂TiC/Fe复合涂层组织及形成机理

以TiFe粉和碳的前驱体（石油沥青）为原料通过前驱体碳化复合技术制备了Ti-Fe-C系反应喷涂复合粉末,并用普通火焰喷涂技术制备了TiC/Fe陶瓷金属复合涂层.观测了喷涂粉末、淬熄实验获取的飞行粒子以及涂层的形态、相和组织结构.结果表明：前驱体碳化复合Ti-Fe-C系喷涂粉末有非常紧密的结构;可有效的解决反应喷涂过程中原料粉末分离的问题.在反应火焰喷涂过程中,每一个喷涂粉末颗粒构成独立的微小反应单元,原料之间反应充分.在整个喷涂过程中喷涂粉末经历了熔化扩散、物相形成、碰撞后快速凝固三个阶段.所得涂层由TiC和Ti2O3共生聚集片层和细小TiC颗粒弥散分布于金属基体所形成的内晶型复合强化片层交替叠加而成.     

Fe—Ti—C熔体中TiC颗粒的原位合成及长大过程研究

本文研究了Ｆｅ－Ｔｉ－Ｃ合金溶体中原位ＴｉＣ颗粒的形成过程。结果表明：在合金熔体的等温过程中,Ｔｉ和Ｃ原子首先不断反应合成ＴｉＣ颗粒,址对生成的ＴｉＣ与熔体达到不平衡;然后,ＴｉＣ颗粒按照小颗粒不断溶解。大颗粒相应在粗化的模式而长大。其中,ＴｉＣ颗粒的合成过程又可进一步分为ＴｉＣ晶核的形成和长大两个阶段越长,本中ＴｉＣ颗粒的数目越多,尺寸越小,而当ＴｉＣ的合成反应平衡后,如继续延长等温时间,则熔体     

Diffusion, Intrusion and Reaction between Al-Containing In-termetallics and TiC Sintered Body during Thermal Pressure Holding

分别以Fe40Al、Ni3Al和TiAl(NbCr)金属间化合物为基体,在一定的压力和温度下,使其和低孔隙率TiC粉体烧结体有效结合。采用扫描电镜及能谱仪等对其界面的组织结构进行分析。结果表明,所有金属间化合物均与TiC烧结体形成了冶金结合的界面。TiC烧结体在高温保压过程中有微量分解,扩散进入了Fe40Al和Ni3Al基体表层,降低了其熔点,从而使其成为可流动状态,被挤压进入TiC烧结体的孔隙。但TiAl(NbCr)合金未能进入TiC烧结体孔隙,而是在与TiC的界面处形成了一层Ti含量高于基体约10at%的反应层。     

45（Ti＋C）＋55Fe（wt－％）的自蔓延燃烧反应过程

采用强制冷却方法使成分为４５（Ｔｉ＋Ｃ）＋５５Ｆｅ（ｗｔ－％）的混合粉压坯在燃烧合成时自行熄灭，得到了保留组织转变过程的产物。对其进行了Ｘ射线衍射分析和扫描电镜观察，计算了燃烧绝热温度Ｔ_（ａｄ），测定了实际燃烧温度Ｔ_ｃ和燃烧波温度轮廓。结果表明，燃烧是以固态反应为主的；固态反应引起了Ｔｉ粉和Ｆｅ粉内燃烧反应的非同步性，ＴｉＣ粒子分别在原Ｔｉ粉和Ｆｅ粉的位置相继形成；固态反应还导致了反应的不完全性，原子固态扩散的较低速率使尺寸较大的Ｆｅ粉内残留少量无ＴｉＣ粒子分布区。     

浇注条件下Fe-Ti-C系粉末压坯一维传热模型的研究

在浇注条件下,制备TiC/Fe复合材料,并对Fe-Ti-C系粉末压坯的轴向一维温度场进行测试,分析其传热规律,建立传热模型,得到模拟的温度场曲线.通过和实际浇注条件下得到的温度场曲线进行对比,此模型能模拟出其升降温趋势.通过测定浇注过程中铁液的温度场,分析粉末压坯的传热规律,推断其内部的物理化学变化,达到控制过程和提高生产率的目的.     

Effect of TiC particles on the oxidation behavior of 2Cr13 stainless steel in a simulated marine environment at 550°C

In this study, the oxidation behavior of 2Cr13 stainless steels with/without TiC particles was investigated in a simulated marine environment at 550°C. The results showed that TiC particles greatly accelerated the oxidation rate of 2Cr13 steel during the cyclic oxidation reaction. At the same time, the effect of acceleration was alleviated by the small size and uniform distribution of TiC particles. As galvanic corrosion in the vicinity of TiC particles occurred in 3.5% NaCl solution spray, more NaCl particles deposited on the alloy surface, especially in the area around TiC particles. At 550°C, some shell-like oxidation products were generated on the 2Cr13 steel surface due to TiC addition, and then the porous oxidation products provided poor protective ability. Besides, the defect and stress in the oxide scale was reduced due to the small size and uniform distribution of TiC particles in 2Cr13 steel.     

高碳钢与钛丝反应合成TiC/Fe复合材料的组织及耐磨性研究

用钛丝作为增强相加人到高碳钢基体中,通过铸造与热处理的工艺,获得丝状碳化钛增强复合材料.对复合材料的微观组织、摩擦磨损行为进行了系统研究.结果表明,制备得到的TiC硬质相,沿原来钛丝方向分布均匀.尺寸为1～4μm.相对于高碳钢标准试样.该复合材料的耐磨性有了,明显的改善.     

TiC颗粒增强钢基表面复合材料的组织均匀性

为了优化自生TiC颗粒增强钢基表面复合材料的工艺参数,利用真空实型铸渗方法制备了自生TiC颗粒增强钢基表面复合材料,重点研究了自生TiC颗粒增强钢基表面复合材料的组织均匀性。结果表明,从基材和复合层间的界面到复合层表面,TiC颗粒尺寸逐渐增大,圆整度逐渐变差,其中Ti-C-20wt%Fe体系复合层中TiC颗粒的尺寸增长量(由1μm增长到2～3μm)明显小于Ti-C体系(由1～2μm增长到约10μm)。与Ti-C体系相比,Ti-C-20wt%Fe体系制备得到的复合层中元素分布、硬度和TiC颗粒的体积分数较均匀,在复合层相同位置上TiC颗粒较小,圆整度较好。     

MICROSTRUCTURAL EVOLUTION DURING COMBUSTION SYNTHESIS OF TiC-Fe CERMET

１ＩＮＴＲＯＤＵＣＴＩＯＮＳｉｎｃｅｉｔｗａｓｄｉｓｃｏｖｅｒｅｄｉｎ１９６７，ｔｈｅｃｏｍｂｕｓｔｉｏｎｓｙｎｔｈｅｓｉｓｈａｓｂｅｅｎｕｓｅｄｆｏｒｓｙｎｔｈｅｓｉｚｉｎｇａｖａｒｉｅｔｙｏｆｃｏｍｐｏｕｎｄｓａｎｄｃｏｍｐｏｓｉｔｅｓ，ｅｇＴ...     

AZ91D熔体中原位合成TiC颗粒及冲刷腐蚀性能

利用原位合成反应法,在不同温度(740、760和780℃)下对AZ91D镁合金熔体保温40min,制备了TiC/AZ91D镁基复合材料。借助光学显微镜和X射线衍射仪,对TiC/AZ91D镁基复合材料的组织形貌和物相进行观察和分析,并对制备的复合材料在质量分数为3.5%的NaCl溶液+石英砂条件下进行冲刷腐蚀磨损试验。结果表明,在740℃保温40min制备的复合材料主要由α-Mg、β-Mg17Al12和Al3Ti组成。保温温度分别为760℃和780℃时,AZ91D镁合金中均出现了原位合成的TiC颗粒,并且随温度升高,TiC的数量增加。此外,TiC/AZ91D镁基复合材料在3.5%的NaCl溶液+石英砂中的冲刷腐蚀磨损性能随保温温度的升高而增加。经780℃保温40min后的复合材料呈出最好的耐冲刷腐蚀磨损性能,相比于AZ91D镁合金提高了60.5%。     

TiC颗粒强化Ti-30Fe复合材料的摩擦行为

将Ti、Fe和TiC粉末进行低温球磨,并结合放电等离子烧结制备Ti-Fe-x TiC (x=0,3,6,9,质量分数%)复合材料。结果表明:该复合材料中含有β-Ti、β-Ti-Fe、η-Ti4Fe2O0.4以及TiC颗粒。显微组织随着TiC添加量的增加而显著细化。粘着磨损是Ti-Fe-x TiC复合材料的主要磨损机制。随着TiC添加量的增加,摩擦因数(COF)减小,硬度增大。其中,由于Ti-Fe-6TiC复合材料中TiC含量较高,TiC颗粒尺寸小,组织细化程度高,因此,具有最佳的耐磨性能,磨损率仅有1.869×10-5 mm3/(N·m),同时,摩擦因数为0.64。由此可见,TiC颗粒增强Ti-Fe基复合材料在耐磨材料领域具有潜在的应用价值。     

铸造烧结Fe—TiC表面复合材料的制备及其耐磨性原因

运用铸造烧结技术，在铸铁件表面合成了厚度为3～4mm的Fe-TiC表面复合材料，该表面复合材料中同时含有铬的碳化物和大量的TiC颗粒，表面复合材料的硬度由表及里逐步降低，在重载干滑动磨损条件下，表面复合材料显示了良好的耐磨性。