Ti3AlC2陶瓷材料研究进展

综合阐述了合成Ti3AlC2新型陶瓷材料的研究现状.三元层状陶瓷材料Ti3AlC2具有金属和陶瓷的优点.应用SHS、HP、HIP和SPS等方法可以制得高纯度Ti3AlC2材料,然而自蔓延高温合成有着特殊的优点.本文从自蔓延高温合成方面介绍了新型陶瓷材料Ti3AlC2的研究进展.     

Ti、Al、C三元素机械球磨工艺对燃烧合成Ti_3AlC_2相的影响

以金属粉末Ti、Al、C为原料,研究不同Ti、Al、C配比及研磨速度、球料比等研磨参数对燃烧合成Ti3AlC2相结构的影响。结果表明:对n(Ti)∶n(Al)∶n(C)=2∶2∶1体系,研磨速度达到120 r/min时,原始粉料完全参与反应,合成产物中无原始粉料残留;而适当的球料比可在混料阶段产生机械诱发自蔓延现象,压坯中因此出现的TiC晶种为Ti3AlC2的燃烧合成做好组织准备。     

大尺寸Ti3AlC2陶瓷的制备及耐磨性研究

采用燃烧合成结合准热等静压技术(SHS/PHIP)制备了大尺寸Ti3AlC2陶瓷材料(φ240 mm×40mm),利用销-盘式摩擦磨损试验机,研究了不同滑动速度下Ti3AlC2的摩擦磨损性能.结合XRD分析、SEM观察和EDS能谱分析,讨论了Ti3AlC2在不同条件下的摩擦磨损机理.结果表明:载荷分别为30N、50N和70N时,随滑动速度的增大,Ti3AlC2的摩擦因数和磨损率均呈现降低趋势,在载荷70N、滑动速度4.8 m/s时,摩擦因数和磨损率分别为0.24和2×10-6 mm3/N·m;材料磨损以磨损表面磨粒磨损和氧化膜的轻微划痕磨损为主.     

Ti_3AlC_2自蔓延高温合成中组织分析

用燃烧波淬熄法及借助X射线衍射仪(XRD)、扫描电子显微镜(SEM)和能谱分析仪(EDS)研究了Ti3AlC2自蔓延高温合成(SHS)中的显微组织变化,淬熄试样保留了未反应区、预热区、燃烧波前沿、反应区、产物区。试验结果表明,Ti3AlC2自蔓延高温合成机理为溶解-析出-熔化-包晶机制:一方面,Ti和C向Al熔液中溶解,最终导致Al3Ti析出;另一方面,随着C向Ti中扩散,最终导致TiC从Ti-Al-C熔体析出;当温度超过Al3Ti的熔点后,Al3Ti熔化,促使Al3Ti和TiC发生包晶反应生成Ti3AlC2。最终的产物中除了大量的Ti3AlC2外还存在少量Al3Ti和Ti,这与试验使用了较粗的Ti粉有关。     

TiC对自蔓延高温合成Ti3AlC2相的影响

以Ti、Al和C粉末为原料的自蔓延高温合成试验研究结果表明:在n(Ti)∶n(Al)∶n(C)=2∶1∶1体系中,未添加TiC时,合成产物中有大量的杂相Ti2AlC生成;当添加≤22.5%(原子数分数)TiC时,合成产物中TiC的含量减少,Ti3AlC2的含量显著增多,Ti2AlC杂质相消失;添加＞22.5%(原子数分...     

金刚石含量与粒度对自蔓延高温烧结钛铝碳结合剂/金刚石复合材料组织与形貌的影响

采用Ti、Al、石墨和金刚石粉体为原料,通过自蔓延高温烧结制备Ti2AlC结合剂/金刚石复合材料,研究金刚石含量和粒度对该复合材料的物相组成与显微形貌的影响。结果表明,原料粉末发生自蔓延反应,可生成Ti2AlC基体相,同时亦生成TiC和Al_3Ti相。金刚石粒度较细(W5)时,金刚石表面C元素充分地与Ti反应生成TiC,同时基体主相变成TiC和Al,没有Ti_2AlC形成。当金刚石粒度较粗(30/40目)时,基体的主相为Ti_2AlC;金刚石与基体结合紧密。当添加金刚石粒度为120/140目时,基体的主相为Ti_2AlC和TiC。当采用170/200目金刚石为原料时,研究金刚石含量对复合材料基体组成与显微组织的影响时,发现原料中添加10%与20%的金刚石后得到的样品基体的主相为Ti_2AlC、TiC和Al3Ti相与金刚石;金刚石表面均包覆着良好的TiC与Ti_2AlC组织。但是当金刚石含量增加至30%时,基体的主相为TiC,同时含有少量的Ti_2AlC、Ti和Al_3Ti等相;金刚石表面受到一定程度的侵蚀,被一些TiC晶粒所包裹。提出一个Ti-Al-石墨-金刚石体系的自蔓延反应机制,即Ti和Al首先发生化学反应,生成Al_3Ti并放出大量的热,然后,原料中的石墨与金刚石表面转变的石墨都与Ti反应形成TiC,TiC与周围的Ti-Al相不断反应形成Ti2AlC。最后,基体主相为Ti_2AlC,金刚石表面亦形成Ti2AlC。     

以铝为助剂通过机械合金化和热处理制备Ti3SiC2

采用Ti、Si、C单质粉末为原料,添加少量Al元素粉末为助剂,通过机械合金化和热处理制备高纯Ti3SiC2材料。采用XRD和SEM研究该材料的物相组成和显微结构。研究结果表明,机械合金化Ti、Si、C单质混合粉末,会诱发自蔓延反应,生成组成相为TiC、Ti3SiC2、TiSi2和Ti5Si3的粉末与颗粒产物。添加适量的Al元素可消除硅化物,明显促进Ti3SiC2的反应合成。采用Ti、Si、C、Al单质粉末进行机械合金化,可制备出主相为TiC与Ti3SiC2的粉末与颗粒产物。对掺Al机械合金化粉末产物压制后,在900~1 100℃热处理2 h,可制备出纯度大于95%(质量分数)的Ti3SiC2材料,而颗粒产物在900~1 200℃进行热处理,亦可获得纯度为96%的Ti3SiC2材料。但在1 300℃,热处理产物中的Ti3SiC2会发生严重分解,部分分解为TiC和少量硅化物,使产物纯度降低。     

Sn掺杂对SHS法制备三元金属陶瓷Ti3AlC2的影响

分别以3Ti/Al/2C/xSn粉末和2Ti/Al/C/0.9TiC/xSn(x=0,0.1,0.2,0.3,0.4,0.5)为原料自蔓延高温合成Ti3AlC2,利用XRD、SEM着重研究了Sn的添加量对产物中Ti3AlC2含量的影响,确定出当产物中Ti3AlC2含量最高时的x值;研究结果表明:添加适量的Sn可消除产物中的Ti2AlC,明显促进Ti3AlC2的合成,并且当x=0.3时,产物中的Ti3AlC2含量最高,比未添加Sn时的含量增加近20％,但Sn的含量继续增加时,Ti3AlC2的含量陡然下降,产物中随之出现大量的Sn,TiC的含量也明显增多;并分析了Sn对合成产物物相组成的影响.     

机械合金化+热处理制备Ti_3AlC_2材料

采用3Ti/1.1Al/2C粉体为原料,通过机械合金化与热处理,制备高纯Ti3AlC2材料。采用XRD、SEM和EDS对试样的物相组成、微观形貌和微区成分进行分析与表征。结果表明,3Ti/1.1Al/2C粉体机械合金化9 h后,元素粉末间会发生化学反应,合成了TiC和Ti3AlC2的复合粉体材料。粉体材料的晶粒比较细小,颗粒直径约为0.5~2μm。同时产物中有一些坚硬、细小的块体出现,小块体中的TiC和Ti3AlC2晶粒发育良好,TiC晶粒大小约2μm,Ti3AlC2晶粒长约10μm、宽约2μm。对得到的机械合金化粉体进行热处理,经900℃保温2 h可获得组织细小(颗粒直径0.5~1μm)、高纯(96.6%)的Ti3AlC2材料。继续升温,会导致Ti3AlC2材料分解。温度升至1 300℃时,物相分析表明试样仅由TiC相组成,组织致密,TiC晶粒大小约5~10μm。     

无压合成制备高纯度Ti3AlC2粉末材料

以TiC粉、Ti粉、Al粉、C粉和Sn粉为原料,通过无压合成工艺,合成了高纯Ti3 AlC2粉末材料.研究了不同原料组成和不同合成温度(1 300～1 500℃)保温30 min产物的物相组成.最终得出结论,在1 500℃保温30 min后可以得到高纯度的Ti3 AlC2材料,Ti3 AlC2含量高于97%.     

Fabrication and Mechanical Properties of Sm2O3 Doped CeO2 Reinforced Ti3AlC2 Nano Composite

The fabrication process of Sm2O3 doped CeO2 reinforced Ti3AlC2 nano composites including the nano particle dispersion process by a hetero-coagulation process was developed using in-situ synthesis and densification process of Ti3AlC2. The effects of Sm2O2 doped CeO2 nano particles on mechanical properties of Ti3AlC2 were investigated. It was found that the presence of 20SDC nano particles in Ti3AlC2 was very effective to improve the mechanical properties of Ti3AlC2 without spoiling the unique characteristics of Ti3AlC2temary carbide.     

三元层状可加工陶瓷Ti_2AlN的研究进展

对三元层状可加工陶瓷Ti2AlN的电子结构及其力学、抗氧化和热电等性能方面的研究进行了综述。重点阐述了Ti2AlN与Ti2AlC相比,其断裂韧性和维氏硬度较低而电导率较高的原因,介绍了Ti2AlN的制备现状与应用前景。     

自蔓延高温合成Ti3AlC2陶瓷材料

以Ti、Al、C、TiC粉末为原料,研究掺杂Si及Al含量对自蔓延高温合成Ti3AlC2的影响,合成材料的X射线衍射仪(XRD)及扫描电子显微镜(SEM)分析结果表明:物质的量比n(Ti)∶n(Al)∶n(C)∶n(TiC)∶n(Si)=2∶1.2∶1∶0.9∶0.1的原始混合粉末,经50 MPa压力压制的压坯在空气中...     

Preparation of Ti2AlC and Ti3AlC2 MAX Phases by Self-Propagating High-Temperature Synthesis with the Reduction Stage

Russian Journal of Non-Ferrous Metals - This work is devoted to the preparation of powders of Ti2AlC and Ti3AlC2 MAX phases by self-propagating high-temperature synthesis (SHS) using the...     

Fabrication of aluminum–ceramic skeleton composites based on the Ti<Subscript>2</Subscript>AlC MAX phase by SHS compaction

A one-stage manufacturing technology of aluminum–ceramic skeleton composites by combining the processes of self-propagating high-temperature synthesis (SHS) of a porous skeleton formed by the MAX phase of the Ti₂AlC composition and its impregnation by the aluminum melt under pressure (SHS compaction) is considered. A composition of the exothermic charge 2Ti + C + 22.5 wt % Al + 10 wt % TiH₂, which provides the formation of a porous skeleton of the Ti₂AlC phase without impurity phases by the SHS technology, is selected. It is shown that, when impregnating the hot SHS skeleton with aluminum, new phases are formed such as the MAX phase (Ti₃AlC₂), titanium carbide (TiC), and titanium aluminide (Al₃Ti). However, the content of the basic MAX phase remains high, and the ceramic component of the material consists of Ti₂AlC by 76%. When analyzing the microstructure, it is revealed that the composite has certain residual porosity after impregnation and cooling. The influence of the impregnation pressure (q = 22, 28, and 35 MPa) on the distribution of the aluminum content over the height and radius of the diametral sample section is investigated experimentally. It is shown that the nonuniform Al distribution over the sample bulk is caused by the nonuniform pressure and temperature fields, as well as the different compactibility of hot inner and colder outer sample parts. The degree of compaction of characteristic zones is leveled as the impregnation pressure increases, and the composition inhomogeneity over the sample bulk decreases. The difference in aluminum concentration over the sample bulk at q = 35 MPa does not exceed 5%. The SHS-compacted aluminum–ceramic skeleton composite based on the Ti₂AlC MAX phase corresponds to high-strength Al-Zn–Mg–Cu aluminum alloys by the hardness level (HB ≈ 150 kg/mm²).     

Reaction products of Al/TiC composites fabricated by the pressureless infiltration technique

The interfacial reaction products of the Al-Mg/TiC _p composite fabricated by the pressureless infiltration method were analyzed using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and transmission electron microscopy (TEM). During the fabrication of composites, reaction products with various morphologies and sizes were formed in the A1 matrix as well as in the vicinity of the TiC particles by the interfacial reaction between the Al alloy and the TiC particles. From the EDS and selected-area diffraction pattern (SADP) analysis, Al₄C₃, Al₁₈Ti₂Mg₃, Ti₂AlC, Al₃Ti, and TiAl could be identified to form as interfacial reaction products. Both the size and the amount of the reaction products were increased with increasing fabrication temperature as well as fabrication time. Coarse Al₃Ti was barely observed in water-quenched composites, while it was observed at all fabrication temperatures (700 °C to 1000 °C) in furnace-cooled conditions. An erratum to this article is available at .     

Thermal and electrical properties of Nb2AlC, (Ti,Nb)2AlC and Ti2AlC

The heat capacities, thermal-expansion coefficients, thermal and electrical conductivities of Nb₂AlC (actual Nb:Al:C mole fractions: 0.525±0.005, 0.240±0.002, and 0.235±0.005, respectively), Ti₂AlC and (Ti, Nb)₂AlC (actual Ti:Nb:Al:C mole fractions: 0.244±0.005, 0.273±0.005, 0.240±0.003, and 0.244±0.005, respectively) were measured as a function of temperature. These ternaries are good electrical conductors, with a resistivity that increases linearly with increasing temperatures. The resistivity of (Ti, Nb)₂AlC is higher than the other members, indicating a solid-solution scattering effect. The thermal-expansion coefficients, in the 25 °C to 1000 °C temperature range, are comparable and fall in the narrow range of 8.7 to 8.9 × 10⁻⁶ K⁻¹, with that of the solid solution being the highest. They are all good conductors of heat, with thermal conductivities in the range between 15 to 45 W/m K at room temperature. The electronic component of the thermal conductivity is the dominant mechanism at all temperatures for Nb₂AlC and (Ti, Nb)₂AlC. The conductivity of Ti₂AlC, on the other hand, is high because the phonon contribution to the conductivity is nonnegligible.     

High-Energy Mechanical Grinding to Produce Cr2AlC and Ti2AlC Max Phases

Powder Metallurgy and Metal Ceramics - We have developed a method for producing single-phase Cr2AlC and Ti2AlC MAX phases using mechanical activation in a planetary-ball mill, followed by heat...     

热等静压技术制备TiAl合金

用Ti,Al元素混合粉(Ti-34％Al,Ti中含有1.5％TiC,质量分数),采用热等静压技术制备了TiAl合金,研究了热等静压压力对合金的密度,合金的微观结构以及物相等的影响,研究结果表明:随着热等静压压力的升高,合金的密度迅速增大,同时,合金中的Ti_3Al相消失,TiC与其它物质反应并在晶界处形成Ti_2Al相,随着压力的升高,合金收缩率的增大,细小的球状Ti_2AlC相会聚集在一起而变成针状Ti_2AlC,利用HIP技术可以很容易地制备出含C的TiAl复合材料。     

电铝热还原电炉钛渣制备Ti-Al-xFe-ySi合金

利用攀枝花产的电炉钛渣铝热还原一步合成Ti-Al-xFe-ySi多元合金,探索CaO对渣金分离、合金收率及钛收率的影响。当CaO/Al=1.1时,制备的熔渣主要生成了低熔点Al_2O_3·CaO和7Al_2O_3·12CaO相,渣金分离效果最好。合金收率达到62%,Ti收率达到92%,合金中氧含量仅为1.32%。制备的合金主要物相为TiAl_3、TiAl相,而渣中还原出来的Fe替代了TiAl3中的部分Ti形成了Al_3Ti_(0.75)Fe_(0.25)物相,而Si主要与合金中的Ti结合生成了Ti5Si3相,合金中还含有少量的碳与TiAl和TiSi相形成了Ti_3SiC_2和Ti_2AlC新相。