Short SiC fiber/Ti3SiC2 MAX phase composites: Fabrication and creep evaluation

The compressive creep of silicon carbide fiber reinforced Ti₃SiC₂ MAX phase with both fine and coarse microstructure was investigated in the temperature range of 1000-1300°C. Comparison of only steady-state creep was done to understand the response of fabricated composite materials toward creep deformation. It was demonstrated that the fibers are more effective in reducing the creep rates for the coarse microstructure by an increase in activation energy compared to the variant with a finer microstructure, being partly a result of the enhanced creep rates for the microstructure with larger grain size. Grain boundary sliding along with fiber fracture appears to be the main creep mechanism for most of the tested temperature range. However, there are indications for a changed creep mechanism for the fine microstructure for the lowest testing temperature. Local pores are formed to accommodate differences in strain related to creeping matrix and predominantly elastically deformed fibers during creep. Microstructural analysis was done on the material before and after creep to understand the deformation mechanics.     

Synthesis of Ti3SiC2 MAX phase powder through molten salt method

Titanium silicon carbide (Ti₃SiC₂) MAX phase powder was synthesized from elemental reactants using the molten salt synthesis (MSS) method. Optimum experimental parameters were also investigated to determine the purity and synthesis pathway of the Ti₃SiC₂ MAX phase. The results showed that Ti₃SiC₂ was not synthesized using carbon black as the carbon source in the starting materials because of the high quantity of TiC formed along with the TiSi₂ silicide phase. However, Ti₃SiC₂ was successfully synthesized in a relatively high purity (93%) at 1200°C for 2 h using graphite as the source of carbon because of the formation of TiC and Ti₅Si₃ intermediate phases. The Ti₅Si₃ silicide phase was found to play a crucial role in the formation of the Ti₃SiC₂ MAX phase using the MSS method. Moreover, applying a pressure of 150 MPa to the prepared samples and using the eutectic mixture of NaCl–KCl (molar ratio: 1:1) instead of NaCl also resulted in the higher formation of the Ti₃SiC₂ MAX phase. The formation mechanism of Ti₃SiC₂ was determined to be the reaction among Ti₅Si₃, TiC, and residual carbon through the template-growth and dissolution–precipitation mechanisms that occurred at different stages of the synthesis process.     

Ti3SiC2陶瓷粉末的制备

新型层状陶瓷材料Ti3SiC2集金属和陶瓷的优良性能于一身,如良好的导电导热性、耐氧化、耐热震、高弹性模量、高断裂韧性等,在高温结构陶瓷、电刷和电极材料、可加工陶瓷材料、自润滑材料等领域有着广泛的应用前景。本文综合介绍了Ti3SiC2粉末制备的研究进展。此外,作者以Ti／Si／C／Al元素粉为原料,采用无压烧结的方法制备出纯度较高的Ti3SiC2陶瓷粉末,为Ti3SiC2基复合材料的发展开辟了一条新途径。     

三元导电陶瓷Ti3SiC2的研究进展

层状结构的Ti3SiC2属六方晶体结构,结合了金属和陶瓷的许多优异性能,如良好的导热和导电性能,优良的可加工性,耐氧化、耐化学腐蚀,优异的抗热震性,良好的自润滑性等,具有广阔的应用前景.本文介绍了Ti3SiC2的结构和性能,对其制备方法及应用进行了阐述.     

Ti3SiC2及其复合材料的研究现状及发展趋势

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.     

Ti3SiC2陶瓷的制备及性能研究

层状陶瓷材料Ti，SiC2结合了金属和陶瓷的许多优异性质，既具有与金属相似的良好的导热、导电性，良好的可加工性，相对柔软，抗热震性好，可塑性变形等性能，同时又具有与陶瓷相似的抗氧化、耐腐蚀、耐高温等特性；并且还有很好的自润滑性和超低磨擦系数，被认为在许多领域有着广泛的应用前景。     

Ti3SiC2基复合材料的研究现状及发展趋势

Ti3SiC2及Ti3SiC2复合材料是材料研究中的热点领域。介绍了Ti3SiC2基复合材料的体系选择、制备技术及其研究现状。指出了进一步研究应该解决的问题和未来的发展前景。最近，作者采用热压烧结工艺制备高纯致密Ti3SiC2/TiB2复合材料。     

Microstructure and Mechanical Properties of (TiB2 + SiC) Reinforced Ti3SiC2 Composites Synthesized by In Situ Hot Pressing

Fully dense (TiB₂ + SiC) reinforced Ti₃SiC₂ composites with 15 vol% TiB₂ and 0–15 vol% SiC were designed and synthesized by in situ reaction hot pressing. The increase in SiC content promoted densification and significantly inhibited the growth of Ti₃SiC₂ grains. The in situ incorporated TiB₂ and SiC reinforcements showed columnar and equiaxed grains, respectively, providing a strengthening–toughening effect by the synergistic action of particulate reinforcement, grain's pulling out, “self‐reinforcement,” crack deflection, and grain refining. A maximum bending strength of 881 MPa and a fracture toughness of 9.24 MPam^1/2 were obtained at 10 vol% SiC. The Vickers hardness of the composites increased monotonously from 9.6 to 12.5 GPa.     

Fabrication and Properties of Ti3SiC2/SiC Composites

Ti3SiC2/SiC composites were fabricated by reactive hot pressing method. Effects of hot pressing temperature, the content and particle size of SiC on phase composition, densification, mechanical properties and behavior of stress-strain of the composites were investigated. The results showed that ： （ 1 ） Hot-pressing temperature influenced the phase composition of Ti3SiC2/SiC composites. The flexural strength and fracture toughness of composites increased with hot pressing temperature. （2） It became more difficult for the composites to densify when the content of SiC in composites increased. It need be sintered at higher temperature to get denser composite. The flexural strength and fracture toughness of composites increased when the content of SiC added in composites increased. However, when the content of SiC reached 50 wt%, the flexural strength and fracture toughness of composites decreased due to high content of pore in composites. （3） When the content of SiC was same, Ti3SiC2/SiC composites were denser while the particle size of SiC added in composites is 12. 8 μm compared with the composites that the particle size of SiC added is 3 μm. The flexural strength and fracture toughness of composites increased with the increase of particle size of SiC added in composites. （4） Ti3SiC2/SiC composites were non-brittle fracture at room temperature.     

微波烧结制备Ti3SiC2-金刚石复合材料的显微形貌及界面反应机理

采用Ti3SiC2粉体和金刚石粉体为原料,通过微波烧结制备Ti3SiC2结合剂金刚石复合材料,研究金刚石的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,通过高温微波烧结Ti3SiC2结合剂金刚石复合材料,金刚石表面会形成不同的涂层,从而与基体结合剂结合良好.金刚石的粒度和含量对复合材料中基体组成和金刚石的表面涂层状态有显著影响.烧结过程中,金刚石会不同程度的影响Ti3SiC2的分解.Ti3SiC2分解后生成Si与TiC.当金刚石含量相同(10％)、粒度较粗(30/40)时,金刚石表面会形成钛硅相与SiC涂层组织;基体的主相为Ti3SiC2、钛硅相与SiC.当金刚石粒度较细(W20)时,金刚石表面的C元素充分地与Si反应生成SiC涂层,基体主相变成TiC和Ti3SiC2.当金刚石粒度适中(120/140目与170/200目)时,基体的主相为Ti3SiC2.选取金刚石粒度为170/200目、金刚石含量较低时(5％与10％),基体的组成为Ti3SiC2与少量的SiC.金刚石含量较高时(20％与30％),基体的组成为Ti3SiC2与少量的TiC和SiC.各试样中金刚石表面都会形成钛硅相与SiC涂层组织.     

Fabrication of Ti3SiC2-Ti4SiC3-SiC ceramic composites through carbosilicothermic reduction of TiO2

Dense Ti₃SiC₂-SiC, Ti₄SiC₃-SiC, and Ti₃SiC₂-Ti₄SiC₃-SiC ceramic composites were fabricated through carbosilicothermic reduction of TiO₂ under vacuum, followed by hot pressing of the as-synthesized products under 25 MPa at 1600°C. In the reduction step, SiC either alone or in combination with elemental Si was used as a reductant. A one-third excess of SiC was added in the reaction mixtures in order to ensure the presence of approximately 30 vol.% SiC in the products of synthesis. During the hot pressing step, the samples that contained Ti₃SiC₂ showed better densification compared to those containing Ti₄SiC₃. The obtained composites exhibited the strength properties typical of coarse-grained MAX-phase ceramics. The flexural strength values of 424 and 321 MPa were achieved in Ti₃SiC₂-SiC, and Ti₃SiC₂-Ti₄SiC₃-SiC composites, respectively. The fracture toughness values were 5.7 MPa·m^1/2.     

可加工陶瓷Ti3SiC2的合成和性能

可加工的Ti3SiC2陶瓷属于六方晶体结构。空间群为R63／mmc。它有许多独特的优良性能。如很好的导电、导热能力。高温延展性、抗热震，高强度。抗氧化。耐腐蚀。超低摩擦性。良好的自润滑性等。制备该化合物的方法主要有CVD,SHS,HP/HIP等方法。作者以元素粉为原料。用等离子放电烧结(SPS)方法成功地制备了高纯的Ti3SiC2陶瓷。     

Electrochemical corrosion behaviors of Ti3SiC2/Cu composites in a 3.5% NaCl solution

The electrochemical corrosion behaviors of Ti₃SiC₂/Cu composite and polycrystalline Ti₃SiC₂ in a 3.5% NaCl medium were investigated by dynamic potential polarization, potentiostat polarization, and electrochemical impedance spectroscopy. The polycrystalline Ti₃SiC₂ was tested on the identical condition as a control. The characterizations of XRD, X-ray photoelectron spectroscopy, scanning electron microscope, and energy-dispersive spectrometer were used to study the relevant passivation behavior and corrosive mechanism. The self-corrosion current density of Ti₃SiC₂/Cu (6.46 × 10⁻⁶ A/cm²) was slightly higher than that of Ti₃SiC₂ (1.64 × 10⁻⁷ A/cm²). Under open circuit potential, the corrosion resistance of Ti₃SiC₂/Cu was better than that of Ti₃SiC₂. Ti₃SiC₂/Cu exhibited a typical passivation feature with a narrow passivation interval and a breakdown phenomenon. The better corrosion resistance of Ti₃SiC₂ was due to the more stable Si layer of the former. In comparison, for Ti₃SiC₂/Cu composites, Cu reacted with the reactive Si layers in Ti₃SiC₂ to form Cu–Si compounds and TiC, destroying the weak interaction between Si layers and Ti–C layers. In the other hand, the as-formed Cu–Si compounds and TiC dissolved during the corrosion of Ti₃SiC₂/Cu in the 3.5% NaCl medium, causing to the destruction of the passivation film on its surface.     

Ti3SiC2陶瓷粉末的制备

新型层状陶瓷材料Ti3SiC2集金属和陶瓷的优良性能于一身,如低密度、高熔点、良好的导电导热性、高弹性模量、高断裂韧性、耐氧化、耐热震、易加工且有良好的自润滑性。在高温结构陶瓷、电刷和电极材料、可加工陶瓷材料、自润滑材料等领域有着广泛的应用前景。本文综合介绍了Ti3SiC2粉求制备的研究进展。最近,作者以Ti／Si／C／Al元素粉为原料,采用无压烧结的方法制备出纯度较高的Ti3SiC2陶瓷粉末。为Ti3SiC2基复合材料的发展开辟了一条新途径。     

Ti_3SiC_2耐氢氟酸腐蚀性研究

在Ar气氛中,以TiH_2/Si/2Ti C复合粉体为原料,利用无压烧结技术在1500°C下保温3 h成功制备出高纯Ti_3SiC_2,并利用氢氟酸对Ti_3SiC_2粉体进行刻蚀,研究其耐腐蚀性。XRD检测结果表明,在常压下Ti_3SiC_2样品经氢氟酸腐蚀前后的物相没有发生变化,且不随反应时间和温度的变化而发生变化。但是,扫描电镜图片显示样品中存在一些二维片层和腐蚀孔洞,这表明HF与Ti_3SiC_2发生了部分刻蚀反应。由于Ti_3SiC_2与酸的反应活性依赖于Si与酸的反应活性,而Si与HF在常压下反应较慢,因此Ti_3SiC_2与HF反应较困难。然而,Ti_3SiC_2与HF在180°C水热条件下则能完全反应,晶体结构遭到破坏,这表明Ti_3SiC_2在常温常压下对HF具有良好的耐腐蚀性,而在水热条件下Ti_3SiC_2易受HF的腐蚀。     

Ti3SiC2/4SiC复相陶瓷的高温力学性能研究

为了进一步了解Ti3SiC2/nSiC复合材料优良的综合性能,特别是其高温力学性能,本文以热等静压原位合成技术制备的Ti3SiC2/4SiC复相陶瓷为试验材料,对其高温拉伸和高温弯曲行为进行研究。结果表明:Ti3SiC2/4SiC复相陶瓷的高温抗拉强度比室温抗拉强度高;Ti3SiC2/4SiC复相陶瓷的高温抗弯强度在900℃出现一极大值,1000℃后具有好的高温塑性。     

用热压法制备Ti3SiC2层状陶瓷的研究

以TiC/Si/Al/Ti为原料 ,采用热压工艺制备出高纯致密的块体材料 ,合成材料的X -射线 ,扫描电镜 (SEM)结合能谱仪 (EDS)分析结果表明 :当烧结温度为 14 0 0℃时 ,合成样品纯度为 98.2 %,晶格参数为a =0 .3 0 69nm ,c =1.767nm ,晶粒尺寸为 4～ 10 μm的板状结晶。材料具有与石墨相似的可加工性能     

Compressive creep of SiC whisker/Ti3SiC2 composites at high temperature in air

The compressive creep of a SiC whisker (SiC_w) reinforced Ti₃SiC₂ MAX phase-based ceramic matrix composites (CMCs) was studied in the temperature range 1100-1300°C in air for a stress range 20-120 MPa. Ti₃SiC₂ containing 0, 10, and 20 vol% of SiC_w was sintered by spark plasma sintering (SPS) for subsequent creep tests. The creep rate of Ti₃SiC₂ decreased by around two orders of magnitude with every additional 10 vol% of SiC_w. The main creep mechanisms of monolithic Ti₃SiC₂ and the 10% CMCs appeared to be the same, whereas for the 20% material, a different mechanism is indicated by changes in stress exponents. The creep rates of 20% composites tend to converge to that of 10% at higher stress. Viscoplastic and viscoelastic creep is believed to be the deformation mechanism for the CMCs, whereas monolithic Ti₃SiC₂ might have undergone only dislocation-based deformation. The rate controlling creep is believed to be dislocation based for all the materials which is also supported by similar activation energies in the range 650-700 kJ/mol.     

Ti_3SiC_2可加工材料的研究现状

Ti3SiC2陶瓷具有很好的高温强度、热稳定性和耐腐蚀性能,同时它还具有很好的导电、导热能力,优良的可加工性,又具备金属良好的高的抗氧化性、抗热震性和高温塑性、良好的自润滑性。本文对其结构、性能以及制备方法和应用前景进行了综合评述。     

新型层状陶瓷Ti3SiC2的研究进展

新型层状陶瓷Ti3SiC2兼有金属和陶瓷的许多优良性能,具有高的热导率和电导率,易加工,同时具有良好的抗热震性、抗氧化性和高温稳定性.本文从层状陶瓷Ti3SiC2制备方法、结构和性能等方面进行综述,并对其应用前景进行展望.