Preparation of Ti3SiC2 with Aluminum by Means of Spark Plasma Sintering

Polycrystalline bulk Ti3SiC2 material with a high purity and density was fabricated by spark plasma sintering from the elemental powder mixture with starting composition of Ti3Si3Si1-xAlxC2 , where x = 0. 05 -0.2. X-ray diffraction patterns and scanning electron microscopy photographs of the fully dense samples show that a proper addition of aluminum promotes the formation, and accelerates the crystal growth rate of Ti3SIC2, conse-quently results in a high purity of the prepared samples. The synthesized Ti3 SiC2 is in plane-shape with a size of about 10- 25μm in the elongated dimension. Solid solution of aluminum decreases the thermal stability of Ti3SiC2, and lowers the temperature of Ti3SiC2 decomposeing to be 1300 ℃ .     

Ti3SiC2的制备方法研究现状

Ti3SiC2材料兼具金属和陶瓷的性能,具有良好的导热性、导电性、自润滑性、耐磨损、高断裂韧性、高温抗氧化等优异性能,有着广阔的应用前景。本文介绍了目前Ti3SiC2材料的制备的方法及其研究现状。     

Ti3SiC2及Ti3SiC2基复合材料的研究现状及发展

介绍了Ti3SiC2陶瓷材料的微观结构与性能，认为该材料良好的综合性能有望解决陶瓷材料的脆性问题．并概述了Ti3SiC2及Ti3SiC2基复合材料各种制备方法的特点和研究状况、应用前景和发展趋势．     

Si对热压法制备Ti3SiC2/SiC复合材料的影响

通过热压法制备了Ti3SiC2／SiC复合材料,并通过扩散偶实验及组织观察,探讨了Si元素对热压制备Ti3SiC2／SiC复合材料的反应过程及组织的影响．结果表明,Si元素在反应过程中起主要作用,决定着反应进行的速度与方向．而且随着反应物中Si量的增加,更有利于Ti3SiC2／SiC复合材料的形成．     

热压烧结Ti3SiC2材料的性能

热压烧结n(TiC)∶n(Ti)∶n(Si)∶n(Al)=2∶1∶1∶0.2的混合粉末制备了含铝Ti3SiC2材料并研究了它的力学性能、电性能、热性能和高温氧化性能。该试样的抗压强度、弯曲强度、断裂韧性和维氏硬度分别为854MPa、420MPa、5.8MPa·m1/2和3.5～5.0GPa;25℃和800℃时的电导率分别为4.3×106S/m和1.0×106S/m;热膨胀系数为9.0×10-6/K。固溶在基体中的Al改变了材料的氧化机理,氧化过程中Al的向外扩散代替了Ti的向外扩散,并在表面形成致密以αAl2O3为主要成分的氧化膜,提高了材料的抗氧化性能。     

Ti3SiC2/TiB2复合材料的制备及其组织和力学性能

以2TiC／Ti／Si／0．2Al／TiB2粉为原料，采用热压烧结工艺成功制备了Ti3SiC2／TiB2复合材料。结果表明：不同TiB2含量的试样中主晶相为Ti3siC2与TiB2两相，没有发现其它杂质相；当复合材料中TiB2的体积分数为10％时，其硬度、抗压强度、弯曲强度、断裂韧性都有显著的提高。经热处理后，Ti3SiC2／10％TiB2复合材料的弯曲强度由367．5MPa     

Cu-Ti3SiC2复合材料真空热压法制备及性能研究

Ti3SiC2是一种具有MAX层状结构的先进材料,兼具金属与陶瓷的双重性能。将Ti3SiC2作为弥散强化相与Cu复合制备金属基复合材料,综合力学性能较好,有望在电接触材料中有较好的应用前景。采用热压烧结法制备Cu-Ti3SiC2复合材料,试验证明Cu-Ti3SiC2复合材料的最佳烧结工艺为:烧结温度750℃,压力30 MPa,保温30min,制得复合材料的组织均匀,团聚较少。其次研究了Ti3SiC2含量对复合材料硬度、电阻率等性能的影响,随着Ti3SiC2的体积分数的增加,硬度先增加后降低,相对密度和抗弯强度呈减小趋势,电阻率增加;通过微观显微分析,Cu-Ti3SiC2致密度随Ti3SiC2含量增加而下降。     

Al2O3对3Ti/Si/2C体系自蔓延高温合成Ti3SiC2的影响

以3Ti/Si/2C粉体为原料,通过自蔓延高温合成技术合成了Ti3SiC2材料。研究了Al2O3助剂对自蔓延高温合成Ti3SiC2的影响。研究结果表明,3Ti/Si/2C粉体会发生自蔓延反应,产物的组成相为TiC、Ti3SiC2和Ti5Si3,产物中Ti3SiC2含量约为23%。添加适量的细粒度Al2O3可显著促进反应合成Ti3SiC2,3Ti/Si/2C/0.1Al2O3原料反应后得到的产物中Ti3SiC2含量达64%。     

The Influence of Mo Additive on the Microstructure and Property of Ti/Al_2O_3 Composite

1　IntroductionBecausethemetal ceramiccompositeisalwaysfabri catedatahightemperature ,theinterfacialreactionbe tweenmatrixandreinforcementisinevitableandformsabrittleinterfacialzone ,whichisdetrimentaltocompositeproperties .Thisisthemaincauseforhinderingtheprepa rationandapplicationoftitaniummatrixcomposites .Atpresent,variousapproachescanbeadoptedtoinhibitorreducethereinforcement matrixreaction .Theuseofhigh speedandlowerprocessingtemperatureduringcompositefabrication ,settingaprotectivecoati…     

Effect of Nb on the Mechanical Properties of Ti／Al2O3 Composite

1　IntroductionMetallic Titanium and alloy are necessary to theaerospace materials because they have excellent propertiesof low density, high strength, and resistance to high tem perature and erosion. And alumina has fine properties ofcalorifics, m…     

Si和Al对机械合金化合成Ti3SiC2的影响

采用3Ti／Si／2C单质粉体为原料,进行机械合金化,以合成Ti3SiC2粉体。研究了Al和过量Si对机械合金化合成Ti3SiC2的影响。研究结果表明,机械合金化单质混合粉体,会诱发自蔓延反应。反应后产生大量坚硬的颗粒状产物。机械合金化3Ti／Si／2C粉体,会产生组成相为TiC、Ti3SiC2、TiSi2和Ti5Si3的粉体与颗粒产物。添过量Si并不会促进机械合金化反应合成Ti3SiC2。添适量Al可消除硅化物,明显促进反应合成Ti3SiC2。采用3Ti／Si／2C／0．15Al粉体作原料时,颗粒产物中Ti3SiC2含量最高,为92．8wt％;而采用3Ti／Si／2C／0．20Al粉体作原料时,粉体产物中Ti3SiC2含量最高,为61．9wt％。     

Electronic Structure and Chemical Bond of Ti3SiC2 and Adding Al Element

The relation among electronic structure, chemical bond and property of Ti3SiC2 and Al-doped was studied by density function and discrete variation （ DFT- DVM） method. When Al element is added into Ti3 SiC2 , there is a less difference of ionic bond, which does not play a leading role to influent the properties. After adding Al, the covalent bond of Al and the near Ti becomes somewhat weaker, but the covalent bond of Al and the Si in the same layer is obviously stronger than that of Si and Si before adding. Therefore, in preparation of Ti3 SiC2 , adding a proper quantity of Al can promote the formation of Ti3 SiC2 . The density of stnte shows that there is a mixed conductor character in both of Ti3 SiC2 and adding Al element. Ti3 SiC2 is with more tendencies to form a semiconductor. The total density of state near Fermi lever after adding Al is larger than that before adding, so the electric conductivity may increase after adding Al.     

Tribological properties of TiAl-Ti3SiC2 composites

The tribological properties of TiAl-Ti_3SiC_2 composites （TMC） against Si_3N_4 ceramic ball pair at room temperature were investigated through the determination of friction coefficients and wear rates, and the morphologies and compositions of wear debris, worn surfaces of TMC and Si_3N_4 ceramic ball were analyzed. The experimental results showed that TMC with 15wt% Ti_3SiC_2 exhibited relatively excellent tribological properties. The solid-phase self-lubricating tribo-layers formed on the worn surfaces of both TMC with 15wt% Ti, SiC, and Si,NA ceramic ball, which was beneficial to the lower friction coefficient and wear rate.     

Electronic Structures and Bonding Properties of Ti_2AlC and Ti_3AlC_2

The relation among electronic structure, chemical bond and property of Ti2AlC, Ti3AlC2 and doping Si into Ti2AlC was studied by density function and the discrete variation (DFT-DVM) method. After adding Si into Ti2AlC, the interaction between Si and Ti is weaker than that between Al and Ti, and the strengths of ionic and covalent bonds decrease both. The ionic and covalent bonds in Ti3AlC2, especially in Ti-Al, are stronger than those in Ti2AlC. Therefore, in synthesis of Ti2AlC, the addition of Si enhances the Ti3AlC2 content instead of Ti2AlC. The density of state (DOS) shows that there is mixed conductor characteristic in Ti2AlC and Ti3AlC2. The DOS of Ti3AlC2 is much like that of Ti2AlC. Ti2SixAl1-xC has more obvious tendency to form a semiconductor than Ti2AlC, which is seen from the obvious difference of partial DOS between Si and Al 3p.     

Fabrication of Ti_2AlC by Spark Plasma Sintering from Elemental Powders and Thermodynamics Analysis of Ti-Al-C System

A ternary-layered carbide Ti 2 AlC material could be synthesized by spark plasma sintering(SPS)technology using elemental powder mixture of Ti,Al and active carbon.By means of XRD and SEM,phases were identified and microscopically evaluated.The experimental results show that the main phase in the product was fully crystallized Ti 2 AlC with small particle size when sintered at 1200 C.The syn-thesis temperature of SPS was 200-400 C lower than that of hot pressing(HP)or hot isostatic pressing(HIP). Through thermodynamics calculations,the mechanism of Ti 2 AlC was studied by calculating changes of Gibbs free energy of reactions.