(Ti,W)(B,C,N)纳米晶粉末的合成

以偏钛酸、偏钨酸铵、木糖、硼酸为原料,采用"前驱体+碳热还原"法合成了(Ti,W)(B,C,N)纳米晶粉末。利用SEM、XRD等表征产物相组成和显微形貌,重点探讨了合成温度、保温时间对合成产物的影响。结果表明,合成温度、保温时间均对(Ti,W)(B,C,N)粉末合成有显著影响,随着合成温度的提高以及保温时间的延长,合成粉末晶粒尺寸呈明显长大趋势。在合成温度1 200℃,保温时间2h条件下成功合成了晶粒度约为21.3nm的(Ti,W)(B,C,N)纳米晶粉末。与传统的"普通球磨+碳热还原"法比较,"前驱体+碳热还原"法显著降低了合成温度,并具有原料成本低廉的优势。     

纳米(Ti,50W)C固溶体粉末的制备研究

采用前驱体与真空碳热还原相结合的方法制备出(Ti,50W)C固溶体粉末,并利用XRD、SEM和FESEM研究了合成温度和保温时间等工艺参数对(Ti,50W)C固溶体粉末微观形貌和相组成的影响。实验结果表明:在合成温度1 100℃、保温时间2.0h条件下能制备出粉末粒径小于100nm的(Ti,50W)C固溶体粉末。与传统工业制备方法相比,本法制备的(Ti,50W)C固溶体粉末所需合成温度更低,原料成本也更低廉。     

“前驱体+真空碳热还原”法制备超细Mo_2C粉末的研究

利用"前驱体+真空碳热还原"法制备了超细Mo_2C粉末,采用XRD、FESEM等表征手段研究配碳量、合成温度以及保温时间对Mo_2C粉末微观形貌和物相组成的影响。结果表明:在配碳量为150%(质量分数)、合成温度1 150℃、保温2.0 h条件下制备的超细Mo_2C粉末,粒径约为100~500 nm。     

高强度帘线钢中氮化钛夹杂的固溶行为分析

为了提高帘线钢盘条的质量,实现轧制过程高强度帘线钢中大颗粒氮化钛夹杂的有效控制,通过试验钢中氮化钛夹杂的固溶试验研究,探讨了高强度帘线钢在加热过程中氮化钛夹杂的固溶行为和影响机制。结果表明,氮化钛夹杂在加热升温阶段存在较为明显的固溶行为,且固溶效果与加热温度和保温时间密切相关。通过适当提高轧钢加热炉温度和延长保温时间以及随后的快速冷却,可以对高强度帘线钢中大颗粒氮化钛夹杂的尺寸和数量进行有效控制。     

熔盐法制备氮化钛粉末的试验研究

氮化钛材料具有优异性能而被用作工具材料、结构材料和用于耐磨与饰面涂层等.本论文以工业级钛白粉和碳黑为原料,利用熔盐合成法在埋碳条件下于1 300℃×4 h制得了氮化钛粉末,并用XRD、SEM和EDS等测试手段对粉末进行了表征.     

熔融盐法合成Cr_2AlC陶瓷粉体的工艺研究

采用正交实验法,研究了在碳热还原气氛保护下的熔融盐中合成Cr2AlC陶瓷粉体工艺中的助溶剂用量、合成温度、原料配比及保温时间对Cr2AlC相对产出率的影响,优化了合成工艺参数,对优化的工艺参数进行了实验验证,并与在氩气气氛和大气气氛合成的粉体相比较。结果表明:实验中影响Cr2AlC产出率的最主要因素是合成温度,其次是助溶剂用量和保温时间,原料配比是最弱因素;碳热还原气氛与氩气具有相同的防止原料氧化的保护作用。     

钛微合金钢中碳氮化钛固溶量及化学组成的计算与分析

根据相关热力学理论,提出了钛微合金钢中钛、碳、氮元素在奥氏体中的平衡固溶量及平衡沉淀析出的碳氮化钛的化学式系数的理论计算方法,对典型化学成分的钛微合金钢进行了理论计算并对计算结果进行了分析.结果表明,通常情况下在较高温度析出或未溶的碳氮化钛相当接近于TiN.     

水解沉淀-碳热还原氮化法制备碳氮化钛粉末

以四氯化钛、炭黑为原料,利用水解沉淀-碳热还原氮化法制备了碳氮化钛粉末.利用差热分析、X射线衍射及扫描电镜等表征手段,研究了合成工艺对粉末物相、组成及形貌等的影响.结果发现:前驱体粉末经350 ℃煅烧2h后,钛以TiO2的形式存在,TiO2与炭黑形成了混合均匀的团聚体:在碳热还原氮化反应时,钛氧化物向TiCxNyOz转...     

0.02～0.05Ti微合金化钢中Ti(C,N)的Ostwald熟化规律

对(%)0.2C、0.004～0.008N、0.02～0.05Ti微合金化钢中Ti(C,N)在850～1400℃的Ostwald熟化规律进行了理论计算。结果表明,1000℃以下碳氮化钛的粗化速率系数m小于1 nm/s~(1/3),1400℃为4～5nm/s~(1/3)。钢中氮含量相同时,相同温度下碳氮化钛的粗化速率随钢中钛含量的增加而增大,因而降低钢中钛含量对碳氮化钛的熟化过程明显有利。而相同钛含量时,相同温度下碳氮化钛的粗化速率随钢中氮含量的增加而显著降低,这表明电炉钢中碳氮化钛颗粒比转炉钢更不容易发生粗化。     

CaB6的反应合成

研究了利用CaCO3、B4C粉和活性炭粉制备CaB6粉末的反应合成工艺,X射线衍射分析了不同反应温度和保温时间条件下所生成粉末的相组成,利用扫描电镜分析了所生成CaB6粉末的颗粒尺寸及形貌,实验结果表明,CaCO3－B4C－C系制备CaB6粉末是一种固相反应过程,其间要经过CaB2O6、CaB2C2等过渡相的生成过程,反应合成CaB6粉末的优化工艺是在10^-2Pa的真空条件下,1400℃保温2．5h。所合成的CaB6粉末与原材料B4C粉的形状相似,通过改善原材料颗粒形貌可优化CaB6粉末形貌及性能。     

Precipitation and Solid Solution of Titanium Carbonitride Inclusions in Hypereutectoid Tire Cord Steel

The properties of titanium carbonitride Ti(C_xN_(1-x))inclusions precipitated during solidification of tire cord steels and the thermodynamic conditions for their decomposition and solid solution during billet heating were investigated using a thermodynamics method.The solid solution of Ti(C_xN_(1-x))inclusions during high-temperature heating was also studied experimentally.The results revealed that:(1)the higher the content of carbon in the tire cord steel is,the greater the value of xin the Ti(C_xN_(1-x))inclusions is;(2)the higher the content of carbon in the tire cord steel is,the earlier the Ti(C_xN_(1-x))inclusions precipitated during the solidification process and the lower the solidification front temperature is during precipitation;(3)when an 82 Asteel sample was heated to 1 087℃,the Ti(C_xN_(1-x))inclusions possess the thermodynamic conditions of decomposition and solid solution;and(4)when 82 Asamples were heated to 1 150 and 1 250 ℃,the total number of Ti(C_xN_(1-x))inclusions larger than 5 μm in diameter decreased by55.0% and 70.3%,respectively.In addition,although smaller inclusions with diameter less than 2 μm continued to decompose when the sample was heated at 1 250℃for 2 hand then cooled to 1 000℃in the furnace,the number of inclusions larger than 5 μm in diameter increased.     

帘线钢中钛夹杂的控制

为了控制帘线钢中的钛夹杂,要同时降低钢水中的w(Ti)及w(N)。通过采用低钛合金、优化转炉出钢工艺、控制转炉下渣量等措施控制钢水中的w(Ti);采用低氮增碳剂,优化全工序降氮操作等措施降低钢水中的w(N)。实践表明:当钢中w(Ti)控制在不大于0.000 4%,w(N)控制在不大于0.004%时,能显著降低甚至杜绝钛夹杂的析出。     

熔盐电解中钛离子电化学沉积行为研究

对熔盐电解提钛工艺中钛离子的电化学沉积行为进行研究,首先通过调整TiCl_4和海绵钛的比例在NaClKCl熔盐中反应制备出不同电解质组分,然后在制备的电解质体系中研究钛离子的电化学沉积行为。低价钛电解质组分的XRD分析结果表明,在993 K的NaCl-KCl熔盐中,当TiCl_4与Ti摩尔比为1∶2时,反应产物主要为2价的TiCl_2,电解质形成NaCl-KCl-TiCl_2体系;当摩尔比为2∶1时,反应产物主要为2.57价的TiCl_2和K_3TiCl_6,电解质形成NaCl-KCl-TiCl_2-K_3TiCl_6体系。两种电解质体系的循环伏安研究结果表明,NaCl-KCl-TiCl_2体系中钛离子的还原历程为Ti~(2+)→Ti,主要受扩散影响,扩散系数为2.93×10~(-5)cm~2/s,而NaCl-KCl-TiCl_2-K_2TiCl_6体系中钛离子还原历程为Ti~(3+)→Ti~(2+)和Ti~(2+)→Ti两步。钛离子电化学沉积产物的SEM分析结果表明在NaCl-KCl-TiCl_2体系中,得到的钛粉产物呈现大颗粒的枝晶状,随着电流密度增大和钛离子浓度减小,钛粉产物颗粒逐步变细;而在NaCl-KCl-TiCl_2-K_2TiCl_6体系中获得产物为细颗粒的多孔状钛粉。     

高炉炉缸内碳氮化钛的生成机理研究

从热力学和热模拟试验两个方面研究了碳饱和铁浴内碳氮化钛的生成机理。利用CONFOCAL激光高温显微镜的试验数据重新确定了钛在碳饱和铁浴内的溶解度和碳氮化钛形成所需的最低钛含量。结果表明在碳饱和铁浴内生成碳化钛和氮化钛的最低钛含量较采用现行热力学数据计算的结果要低。采用长坩埚法研究了不同温度梯度条件下碳氮化钛的形成，结果发现碳氮化钛在温度梯度较大的耐火材料和铁水界面有团聚行为     

钛与钛合金的低成本清洁制备新技术

提出了多级深度热还原的理念,发明了镁热/铝热自蔓延-深度多级还原制备钛与钛合金的关键技术,成功制备出纯度为99.69%高纯还原钛粉,Ti6Al4V合金粉：Ti:89.5-90.2%、Al:5.85-6.57%、V:3.90-4.17%,氧含量<0.15%;制备出20kg级规模的TiAl合金铸锭,Ti/Al原子比为1:1,氧含量为0.09%。成果已在山东傅山集团成功转化应用,500t/a还原钛粉工业示范线于2018年12月08日试车成功,可使金属钛与钛合金的生产成本降低30%以上,项目的推广应用为钛材低成本清洁利用奠定工业化基础。     

配碳量对自蔓延镁热还原反应制备TiCN粉末的影响

在自蔓延高温镁热还原反应制备Ti（C，N）粉体的研究巾，考察了配碳量对TiC1-xNx粉末的相组成、组成成分和微观组织的影响。试验结果表明：随着配碳量的增加，产物的碳含量增加，氮含量相应减小，但过高的配碳量会导致游离碳的产生，过低的配碳量则导致过高的氧含量，当配碳量在0．3～0．7mol之间时得到的TiC1-xNx粉末的性能最好；随着原料中碳粉含量的增加，产物组织颗粒逐渐变得细小，均匀。     

HRB500E抗震钢筋中钛化物析出热力学分析

 钢液凝固过程中钛化物在液相、固相的存在形态对固相组织的性能有着重要的影响,其第二相析出起到细化晶粒的作用。为分析HRB500E抗震钢筋钢中TiN、TiC、Ti(C,N)析出物的析出规律,对TiN、TiC、Ti(C,N)析出物进行热力学计算。结果表明,TiN、TiC在钢液成分均质状态下难以析出,TiC_0.19N_0.81在温度为1 843 K时析出;在凝固过程中,由于Ti、N在凝固前沿富集,TiN在凝固过程中具备析出的热力学条件,析出温度为1 745 K;在固相奥氏体中,TiN和TiC粒子具备析出热力学条件,TiC析出温度比TiN的低,铁素体中有TiC的析出。     

Precipitates in Steels With Ti Additive Produced by CSP Process

 Hot strips of low carbon steels with Ti additive [contain C 004%-007%, Si≤06%, Mn≤06%, Ti 006%-014% (mass percent)] produced by EAF CSP (Electric Arc Furnaces Compact Strip Production) process were examined by TEM, HREM and XRD. Carbonitrides with different N/C ratio were found in the samples. The varying composition of the Ti carbonitrides resulted from the supersaturation of Ti and temperature at which the compound was formed. In the tested steel, total mass fraction of the precipitates including cementite, carbonitride and a small quantity of Fe3O4, Al2O3, Ti2CS and AlN was about 0305%. XRD results showed that about a quarter of the powder extracted by electrolysis was titanium nitrides, carbonitrides and carbides. Particle arrays formed by interphase precipitation could be observed either in slabs or in hot strips. The dominant reaction mechanisms were discussed. Compared with the conventional cold charge process, small amount of Ti addition would be more effective for precipitation of fine precipitates in the steels produced by CSP process.     

Surface chemistry of the titanium powder studied by XPS using internal standard reference

Surface chemistry of the titanium powder has particularly growing interest due to the increasing application of titanium components prepared by powder metallurgy, in particular metal injection moulding and additive manufacturing. Due to the high chemical activity, number of titanium oxides, calcium and complex Ca–Ti–oxides can be expected on the component/medical implant surface, depending on powder and component manufacturing and post-treatment, but are very difficult to analyse due to the lack of the experimental data and analysis methodology. Therefore, a methodology for the analysis of the surface chemistry of the Ti-powder by XPS utilising internal standard reference was developed. The obtained methodology was used for the surface analysis of titanium powder and identification of its surface oxide composition. The results show that the powder surface is covered by TiO₂ layer in the form of rutile with a thickness of 4.4?nm. Carbon and nitrogen impurities were also found present on the powder surface.