反应烧结制备Ti_2AlN-TiN复合材料

采用2Ti/2Al/3TiN粉体为原料,通过反应热压烧结,以制备Ti2AlN-TiN复合材料。采用X射线衍射（XRD）、场发射扫描电镜（FE-SEM）结合能谱仪（EDS）分析试样。研究结果表明,在1350℃保温2h,压力为30MPa,可烧结得到组织细小、致密的Ti2AlN-TiN复合材料。材料中层片状Ti2AlN晶粒长约5m,TiN晶粒大小为1~2m。复合材料具有良好的机械性能,其显微硬度与弯曲强度分别达8.57GPa和450MPa。     

块体Ti2AlN多晶陶瓷的制备研究

Ti、Al和TiN粉按化学计量比配料，在原位热压（HP）和放电等离子（SPS）2种烧结工艺条件下可以合成单相块体Ti2AlN多晶陶瓷材料。通过X射线衍射（XRD）分析烧结产物的相组成。用扫描电镜（SEM）研究材料的显微结构特征。原位热压工艺合成Ti2AlN的最佳温度为1300℃，烧结试样的密度为4．22g／cm^3，达到理论密度的97．9％；放电等离子烧结工艺合成Ti2AlN的最佳温度为1200℃，烧结试样的密度为4．28g／cm^3，达到理论密度的99．3％。且晶体发育完全，结果紧密，具有明显层状结构。     

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     

三元层状Ti_3AlC_2材料的制备及力学性能分析

分别以石墨和TiC为碳源,以微米级Ti粉、Al粉为原料,采用固-液相原位热压烧结方法制备了不同反应物合成的致密层状Ti3AlC2陶瓷材料.采用XRD、SEM分析了产物的形貌和相组成,并对其力学性能进行了分析测试.研究表明:在1 300℃、25 MPa条件下,以TiC/Al/Ti混合粉末体系为原料,热压烧结可以获得纯度较高的致密Ti3AlC2层状陶瓷材料;Ti3AlC2陶瓷材料的断裂韧度KIC为5.60 MPa.m1/2,维氏硬度在HV 400～600之间,抗弯强度为454.7 MPa,抗压强度可达764 MPa.研究表明,晶粒细化是其力学性能提高的主要原因.     

热压TiAl/Ti2AlC复合材料的相形成规律

采取原位热压方法，利用Ti、Al、TiC为原料合成了TiAl／Ti2AlC复合材料。通过X衍射图谱，分析了从600℃到1300℃该合成过程的相形成规律。Ti、Al、TiC的反应大致可分为2个阶段：900℃之前，Ti和Al反应生成TiAl金属化合物；900℃之后，TiAl金属间化合物和TiC反应并合成致密TiAl／Ti：AlC复合材料。讨论了这2个阶段的反应机及烧结产物的微观结构特点。     

脉冲激光沉积制备TiN/AlN多层薄膜的研究

采用脉冲激光沉积(PLA)法,在单晶Si试样表面沉积制备了一系列TiN/AlN硬质多层膜,并采用基于免疫算法的免疫径向基函数(IRBF)神经网络对AlN厚度建立预测模型,设计出具有可控调制周期和调制比的TiN/AlN多层膜。X射线衍射(XRD)结果表明,小调制层周期下,过高或过低的工艺条件下薄膜通常为非晶态,适当的工艺条件下TiN、AlN形成具有强烈织构的超晶格柱状晶多层膜;与此相应,纳米多层膜产生了硬度和弹性模量异常增高;随着调制比增加,使纳米多层膜形成非晶AlN层和纳米晶TiN层的多层结构,多层膜的硬度和弹性模量逐渐下降。XPS结果表明,薄膜界面由Ti+4、Ti+3离子组成,N的负二价、三价亚谱结构预示着非当量TiN、AlN的形成。AFM研究显示,薄膜的调制周期均在10~200 nm范围内,且薄膜表面较均匀;当多层薄膜调制周期在50 nm以下时,薄膜的纳米硬度值明显高于TiN和AlN的混合硬度值,达30 Gpa。     

AlN／MAS微晶玻璃复合材料的热物理性能

通过X射线衍射、扫描电镜和热物理性能测试，研究AIN引入量和温度对在900-1000℃真空热压烧结制备的AIN／MAS玻璃陶瓷复合材料热物理性能的影响。研究结果表明：复合材料的热膨胀系数随着AIN引入量和测试温度的增加而增加；热导率随着AIN引入量的增加而增加；随着测试温度的升高，复合材料的热导率随着AIN引入量的变化呈现不同的特征；AIN引入量为20％（体积分数）时，样品的热导率随着测试温度的升高而升高，表现出明显的非晶态物质的导热特性；AIN引入量为50％时，样品的热导率呈现先升高后稍许降低的导热特性。     

放电等离子烧结制备TiC/7075铝基复合材料实验研究

在实验中运用放电等离子烧结技术制备TiC/7075铝基复合材料,并分析了不同TiC含量的TiC/7075烧结块体的组织结构和力学性能。采用球磨工艺混合7075合金粉和TiC粉末,在500℃下烧结制备TiC/7075铝基复合材料;利用XRD、SEM、EDS、HVS-1000分析烧结块体的物相、微观组织、维氏硬度。研究发现,烧结制备的TiC/7075铝基复合材料中只有Al和TiC相,没有新相形成; TiC在基体材料中分布均匀,制备的烧结块体致密度高达98%,其维氏硬度随着TiC含量的增加而增加。     

等离子烧结法制备FeAl/Al2O3复合材料

利用机械活化-放电等离子烧结的方法,将Fe-Al-Al2O3粉末经机械活化后快速烧结,得到致密且晶粒细小的FeAl/Al2O3块体复合材料.研究表明,在w（球）∶w（粉）=13∶1、转速170 r/min、球磨时间25 h的球磨参数下,粉体中的纳米级Al2O3颗粒,在细化和活化Fe、Al金属粉末的同时,还能有效地阻止金属粉末在烧结前合金化生成金属间化合物.在烧结压力40 MPa、烧结温度1050℃、加热时间15 min、保温时间10min的烧结参数下,制备的FeAl/Al2O3复合材料的致密度可达96.4%.     

Fabrication of MoSi2-SiC Composites by a Spark Plasma Sintering Method

MolybdenUmdisilicidepeoSi,)hashighmeltingpoint(2293K),relativelylowdensity(6.249/cm3),abrittle-to-ductiletemper~atabout1173K[l]andoutstandingoxidationresistance[2M].Forthisreason,thedisilicidematrixcompositesarebeingconsideredasoneofthemoStPromisingc...     

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…     

Preparation of TiAl/Ti2AlC Composites with Ti/Al/C Powders by In-situ Hot Pressing

TiAl/Ti2AlC composites were prepared by in-situ hot pressing of TilAl/C powders mixtures and sintered at different temperatures were investigated by X- ray diffraction （ XRD ） of samples. The reaction procedure of Ti-Al-C system could be divided into three stnges. Below 900℃ , Ti reacts with Al to form TiAl intermetallics ; above 900 ℃ , C reacts with remain Ti to form TiC triggered by the exothermal reaction of Ti and Al ; TiAl reacts with TiC to produce dense TiAl/Ti2AlC compasites.In the holding stage, ternary Ti2AlC develops to layered polycrystal and composites pyknosis in the meanwhile. The mechanism of synthesis and microstructure was especially discussed.     

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.     

脉冲激光沉积TiN/AlN多层膜的微结构与力学性能

采用脉冲激光沉积(LPA)法,在单晶Si表面制备了调制周期为50nm的不同调制比的TiN/AlN多层膜,并研究了调制比对多层膜微结构和力学性能的影响。扫描电镜(SEM)和原子力显微镜(AFM)显示,薄膜的调制比在1～4之间。并且小调制比下薄膜表面的岛密度小,岛面积过大,分布不均匀,相邻岛之间的起伏较大。X射线衍射(XRD)结果表明,小调制比下,AlN相为明显的(002)择优取向,TiN相主要以(200)、(220)形式存在;调制比增大后,AlN相的择优取向减弱,同时伴随着薄膜晶粒的细化及硬度增强,这一研究结果说明,调制比对多层膜的性质有一定的影响,大调制比会导致Al元素在界面处聚集,并与TiN进行合金化后的形成TiAlN结构,进而对薄膜的硬度产生影响。     

Microstructure,Densification, Microhardness and Antioxidant Properties of Ti_2AlN/TiN FGM Fabricated by Hot-pressing

Ti2AlN/TiN functionally graded materials(FGM) were successfully fabricated by vacuum hotpressing. Bulk density of the sintered samples was measured by Archimedes principle. The sample sintered at 1 300 ℃ for 2h has the maximum final density and lowest open porosity. SEM coupled with EDS was utilized to investigate the phase composition and microstructure, and well-formed boundary was found between the layers. The microhardness tests suggest that Vickers' hardness of Ti2AlN/TiN FGM increases monotonically with the volume fraction content of TiN increases. Corrosion results are that the corrosion resistance of Ti2AlN/TiN FGM is much better than that of Ti2AlN in acid, but quite the opposite in alkali. Constant temperature oxidation study shows that the oxidation kinetics of Ti2AlN/TiN FGM at 900 °C follows the parabolic law closely.     

Fabrication of Ti2AlC by Spark Plasma Sintcring from Elemental Powders and Thermodynamics Analysis of Ti-M-C System

A ternary-layered carbide Ti2AlC 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 Ti2AlC with small particle size when sintered at 1200℃. The synthesis temperature of SPS was 200-400℃ lower than that of hot pressing （HP） or hot isostatic pressing （HIP）. Through thermodynamics calculations, the mechanism of Ti2AlC was studied by calculating changes of Gibbs free energy of reactions.