原料组成对Ti3SiC2粉体合成的影响机制

分别以Ti/Si/Cg/Al、Ti/Si/TiC和TiH2/Si/TiC混合粉末为原料,通过球磨和保护气氛无压烧结法,制备Ti3SiC2陶瓷粉末。利用X射线衍射仪和附带能谱仪的场发射扫描电子显微镜对所制备Ti3SiC2粉末的物相、表面形貌、显微结构及元素分布进行对比分析,并探讨原料组成对Ti3SiC2粉体合成的影响机制。结果表明：添加Al元素对Ti3SiC2粉体合成有显著促进作用,用Ti/Si/Cg/Al组分合成的Ti3SiC2粉体的组织结构最优。     

原料组成对Ti_3SiC_2粉体合成的影响

分别以Ti/Si/Cg/Al、Ti/Si/Ti C和Ti H2/Si/TiC混合粉末为原料,采用球磨和保护气氛无压烧结法制备Ti3SiC2陶瓷粉末,利用X射线衍射仪和附带能谱仪的场发射扫描电子显微镜对所制备Ti3SiC2粉末的物相、表面形貌、显微结构及元素分布进行对比分析,探讨原料组成对Ti3SiC2粉体合成的影响。结果表明,添加铝对Ti3SiC2粉体合成有显著促进作用,用Ti/Si/Cg/Al组分合成的Ti3SiC2粉体的组织结构最优。     

“化学炉”辅助燃烧原位合成SiC/MoSi_2复合材料

以Mo、Si和C单质粉为原料,采用自蔓延原位合成技术制备10%SiC、20%SiC(体积分数)强韧化MoSi2复合材料,并从理论上计算了自蔓延燃烧反应绝热温度.结果表明,常规自蔓延能够合成10%SiC/MoSi2复合粉体,而通过"化学炉"辅助燃烧能够合成20%SiC/MoSi2材料.复合粉末主要由MoSi2和SiC相组成,SiC颗粒分布均匀,与MoSi2基体结合良好,其断裂机理为穿晶断裂.     

SiGw/MoSi2的化学炉自蔓延高温合成及反应过程研究

采用"化学炉"自蔓延高温合成(COSHS)技术,成功地原位合成了SiCw/MoSi2复合粉体.通过在原料中引入Si3N4晶须,在产物中获得了SiC晶须.XRD结果表明,产物中除了主要的MoSi2和SiC相,还含有少量的Mo4.8SiC0.6.研究了中间产物的相组成和反应过程中的温度变化,指出"化学炉"自蔓延合成SiCw/MoSi2复合粉体的反应过程包括如下两步反应:①Mo与Si自蔓延反应生成MoSi2;②Si3N4与C反应生成SiC和N2.     

SiCw／MoSi2的化学炉自蔓延高温合成及反应过程研究

采用“化学炉”自蔓延高温合成（COSHS）技术，成功地原位合成了SiCw／MoSi2复合粉体。通过在原料中引入Si3N4晶须，在产物中获得了SiC晶须。XRD结果表明，产物中除了主要的MoSi2和SiC相，还含有少量的Mo4.8SiC0.6。研究了中间产物的相组成和反应过程中的温度变化，指出“化学炉”自蔓延合成SiCw／MoSi2复合粉体的反应过程包括如下两步反应：①Mo与Si自蔓延反应生成MoSi2；②Si3N4与C反应生成SiC和N2。     

冲击波方法合成TiC的影响因素

研究采用乳化炸药爆炸冲击波方法合成TiC的影响因素，即Ti和C粉末配比，初始装填密度，碳原料种类等对反应结果的影响。结果表明：炭黑最易与Ti发生反应生成TiC，具有高装填密度的反应混合物比低装填密度的反应混合容易诱导Ti和C反应的发生，Ti粉和碳黑的反应计量比对反应的结果影响不大，C和Ti原子比在0.6-1.0之间的粉末混合物都安全反应生成致密TiC.     

液相共沉淀法制备BaPbO3导电陶瓷粉末

利用液相共沉淀法，以BaCO3和PbO为原料制备了BaPbO3陶瓷粉末，讨论了原料、焙烧温度、升温速度、保温时间对粉末性能的影响，江用X射线衍射及SEM对粉末的结构和形貌进行了研究．实验结果表明：采用液相共沉淀法能明显降低BaPbO3粉末的合成温度，其合成温度约为650℃左右；液相法制备的BaPbO2粉末的纯度高、粒度细；适当地提高升逼速度可提高BaPbO3粉体的合成率和降低BaPbO3粉体的合成温度．图6，参12．     

等离子喷涂碳化钛-硅化钛涂层的组织结构与性能

研究直接喷涂和反应喷涂合成的两种碳化钛-硅化钛复合涂层的组织结构与性能.通过等离子喷涂技术将两种不同复合粉(TiC-TiSi₂和Ti-SiC)分别喷涂在TC4钛合金表面制备成碳化钛-硅化钛复合涂层,利用X射线衍射仪、扫描电子显微镜、万能拉伸试验机、显微维式硬度计、划痕仪对所得涂层进行表征及测试.结果表明:等离子喷涂TiC-TiSi₂复合粉所得涂层中含TiC为58%,Ti₅Si₃为21%,TiSi₂为7%,Si为9%和SiO₂为5%,等离子喷涂Ti-SiC复合粉所得涂层含有TiC(47%),Ti₅Si₃(40%)和SiC(13%);在等离子喷涂过程中Ti-SiC复合粉中的Ti与SiC发生了明显的化学反应,反应生成了TiC和Ti₅Si₃;等离子喷涂Ti-SiC复合粉所得涂层,具有更薄的层片和更小的晶粒尺寸.与等离子喷涂TiC-TiSi₂复合粉所得碳化钛-硅化钛涂层相比,等离子喷涂Ti-SiC复合粉所得碳化钛-硅化钛涂层具有更高的结合强度、更高的显微硬度(提高了18.7%)、更好的韧性及更好的耐划痕性能,这主要在于等离子喷涂Ti-SiC复合粉反应合成的碳化钛-硅化钛涂层中硬质相的相对含量更高且反应合成的碳化钛、硅化钛晶粒更细小.     

铝熔体中热爆反应合成Al-10Ti中间合金

以Al和Ti粉末为原料,采用铝液中热爆反应技术制备Al-10Ti中间合金晶粒细化剂,通过X射线衍射(XRD)、扫描电镜(SEM)和差热分析仪(DSC)等手段研究铝液温度对反应过程和Al-10Ti中间合金组织形态的影响.结果表明,热爆反应合成的原始产物由Al和Al3Ti两相组成,铝液温度对中间合金中Al3Ti的尺寸、分布有重要影响,800℃铝液中合成的Al-10Ti中间合金具有良好的晶粒细化性能,通过控制铝液温度和原料Al/Ti比可有效控制Al3Ti的组织形态,对细化效果产生影响.     

W/Ti含量对钢铁基复合材料微观组织和相变的影响规律

以Fe、Ti、W和石墨粉为原料,采用真空烧结技术制备铁基复合材料。通过改变粉末中的W/Ti原子比,探究其对复合材料组织和相变的影响规律。结果表明：球磨后的粉末活性有所增加,并出现Ti_xW_1-x不稳定过渡相;材料的相变反应温度会随着粉末中W含量增加而升高,DSC曲线尖锐的放热峰会逐渐变宽、变缓,剧烈的反应得到控制;粉末经烧结后会生成TiC、WC和Ti₄WC₅等增强相,当粉末的W/Ti比从2∶8增加至4∶6时,反应产物中3种增强相的占比从84.09%增加至93.07%,生成物中WC的占比从32.45%迅速增加到78.5%。此外,由于复合材料组织中多种物相的存在,彼此间的取向差异会引起组织中出现微应变。随着粉末中W/Ti比的增加,复合材料组织中的微应变逐渐增大;与粉末W/Ti比为2∶8制得的复合材料相比,粉末的W/Ti比为4∶6时制备的复合材料组织中的微应变提高了2.84倍。因此,通过调节W/Ti含量可实现对钢铁基复合材料微观组织和增强相的优化。     

Current situation and future trend of China rare earth luminescent material industry

<正>Rare earth luminescent material is one of the most important application sectors of rare earths.China enjoys the exceptional advantage to develop rare earth luminescent material for its abundant rare earth resources.After several decades'endeavor,China's rare earth luminescent material industry,headed by rare earth phosphor for lamp and LED and high efficient rare earth energy-saving light source,has been gradually developed into a scale industry.China has become a major production base of rare earth phosphor for lamps and rare earth     

China rare earth market review

正June 1~10,2014Rare earth market remained weak.Quoted price of rare earth products was similar to that in May.There was no sign of recovery in downstream market.The market of NdFeB magnetic materials and phosphor was depressed.Catalyst,polishing powder and ceramic industries remained inactive.Demand from downstream industry was soft.Consumers purchased on their needs.Suppliers had strong intention to sell.Prices of rare earth products     

Annual Report analysis of Chinese rare earth-related listed companies in 2013

<正>Chinese rare earth-related listed companies have published their 2013 annual reports.It can be understood from their reports that production and operation activities of Chinese rare earth-related companies were still heavily affected by macro economy and industrial policies.They basically followed the steps of national economy.In 2013,world economy recovered slowly but the economy     

Market opportunities and challenges for rare earth polishing powder

正1.Status of rare earth polishing powder Rare earth polishing powder with high content of cerium oxide began to replace iron oxide for glass polishing and became one of the key materials in glass polishing process since 1940.Compared with traditional iron oxide,rare earth polishing powder has many advantages,such as fast polishing rate,high polishing quality and long service life.It can achieve good surface quality and improve operation conditions.For example,in lens polishing,the polishing work that cerium     

Baotou Research Institute of Rare Earths developed a new RE alloy preparation technology

正Pyrometallurgy Laboratory of Baotou Research Institute of Rare Earths had independently developed a new preparation technology of rare earth alloy for NdFeB.The alloy can remarkably enhance the coercivity of NdFeB magnet but also evidently reduce the production cost of the magnet.The new master alloy was prepared in the kA pilot-scale electrolytic cell by the independent technology.The rare earth master alloy can be used as the raw material for NdFeB.Compared     

矿用防爆轴流对旋主要通风机叶片ANSYS模态分析及应用

高效节能矿用防爆对旋主要通风机的叶片是主要通风机运行的关键部件,叶片在运行时不断受到气流的作用力,从而使叶片产生振动,当叶片振动的频率与叶片的固有频率接近时,容易产生共振从而导致叶片的断裂。一旦叶片断裂时,对主要通风机的安全运行产生致命的影响,从而导致矿山、化工等企业发生重大事故,将会产生不可估量的损失。基于有限元分析软件ANSYS,对高效节能矿用防爆轴流对旋主要通风机叶片进行模态分析及产生对应的六阶模态频率,对主要通风机叶片的运行频率、固有频率及产生的共振问题进行了原理分析,并且解决了叶片频率共振的问题,从而为主要通风机叶片结构设计提供理论依据,并对主要通风机叶片的安全运行提供保障。     

2013 NdFeB export analysis

<正>China totally exported nearly 24,000 tonsof NdFeB products during 201 3,including 18,825 tons of permanent magnet,valued USD 1.34 billion at an average price of 71.4 USD/kg;3,277 tons of NdFeB magnetic powder,valued USD 1 01 million at an average price of 30.9 USD/kg;1,334 tons of strip casting ribbon,with total export value of USD 74million at an average price of 55.3 USD/kg;and 586     

Market and recycling of NiMH battery

<正>Market status and future trend of NiMH battery1.Global market of small NiMH battery Global market size of small NiMH batteries declined year on year since 2011.The trend will continue to 2018,at the rate of 5%to 10%annually.Demand for small NiMH batteries will be stable gradually.Many electrical apparatuses are powered by the built-in lithium battery today,which is the main reason for the shrunk market of small NiMH batteries.But,for some products,small NiMH     

China rare earth market review

正September 1-10,2014 Affected by the National Day holiday,rare earth transaction was stagnant and the market showed a weak steady state.As there was no good news for downstream market,some products with flat demand would likely rally slightly for some time to     

唐口煤矿深部复杂开采工作面瓦斯分源涌出规律研究

研究工作面瓦斯涌出规律对工作面瓦斯治理有重要意义。为了得到唐口煤矿深部3号煤层复杂开采条件下工作面回采时期瓦斯涌出时空演化规律,选取6304工作面作为对象,采用实测方法研究6304工作面瓦斯涌出规律。结果表明:6304工作面瓦斯涌出量为6.534 m³/min,其中煤壁占34.27%,落煤占29.62%,采空区占36.11%;沿工作面倾向由低到高,瓦斯浓度整体为上升趋势,其中1—76号架工作面瓦斯浓度小于0.20%,76—102号架瓦斯浓度上升明显,最大为0.387%;上隅角的后部采空区是工作面的瓦斯主要涌出源,上隅角1号测点瓦斯浓度0.78%,上隅角周边3号、5号、7号、8号、9号测点瓦斯浓度平均为0.643%;周期来压时,上隅角瓦斯相对平时较高。研究为针对性的瓦斯分源监控与灾害防治提供基础。