新型陶瓷材料Ti3SiC2制备技术的研究进展

Ti3SiC2兼有金属和陶瓷的许多优异性能。因此，Ti3SiC2在作为高温结构材料、自润滑材料以及电极材料等方面具有十分广阔的应用前景。本文重点介绍了Ti3SiC2的各种制备技术，并指出了各自的应用特点和存在的主要问题以及未来的研究方向。     

Ti3SiC2/Cu复合材料的制备与性能

三元层状化合物Ti3SiC2兼具陶瓷和金属的性能,受到材料研究者的广泛关注.该文采用热压工艺制备Ti3SiC2/Cu复合材料,研究Ti3SiC2含量及烧结温度对复合材料密度、抗弯强度、弹性模量、电阻率等性能的影响.结果表明,复合材料的相对密度对其性能有着重要的影响.当Ti3SiC2的质量分数在60％～80％范围内,其它...     

Ti_3SiC_2替代石墨对铜基摩擦材料性能的影响

以Ti3SiC2替代石墨作为减摩剂研制了一种新型的粉末冶金铜基摩擦材料,探讨了Ti3SiC2替代石墨对铜基摩擦材料性能的影响。结果表明:和石墨相比,Ti3SiC2与Cu基体界面发生了扩散反应,增强了与基体的结合能力。试样在高速、高温摩擦磨损试验下获得了较稳定的摩擦系数;高温摩擦试样表面经XRD检测出含有TiO、SiO2薄膜,拥有很好的高温抗氧化能力。     

自蔓燃高温合成碳化物陶瓷

介绍了自蔓延高温合成（SHS）制备碳化物粉体。单晶、多孔材料和致密材料。重点讨论了通过控制反应参数,控制合成材料的组织结构和性能的一些措施。以催化剂载体、泡沫陶瓷过滤器、粗TiC磨料以及Si-SiC复合材料为例,介绍了SHS在材料合成中的应用和控制方法。参考Ti3SiC2陶瓷的合成,讨论了多元SHS体系中产物相的控制问题。另外,文中还介绍了提高烧结助剂BxC在SiC中的分散性,从而提高SHSSiC烧结性的实例。     

层状可加工陶瓷Ti3SiC2自蔓延高温合成反应机理的研究

采用燃烧波淬熄法,以Ti粉、Si粉和C粉为原料研究了层状可加工陶瓷Ti3SiC2在自蔓延高温合成(SHS)中的反应机理.淬熄试样中保留未反应区、反应区和已反应区,用扫描电子显微镜观察燃烧反应中显微组织的转变过程,用能谱仪分析各微区的成分变化,并通过差热分析(DSC-TGA)和XRD分析考察了从600℃到1500℃ Ti-C-Si系统的反应合成过程和相形成规律.结果表明:层状可加工陶瓷Ti3SiC2自蔓延高温合成的机理为溶解-析出机制,Ti粉与Si粉的固态扩散导致低熔点Ti-Si溶液形成,Ti、Si、C粉粒逐渐向Ti-Si溶液中溶解,当溶液中的Ti、Si、C浓度饱和时,从中析出TiC、SiC颗粒,最后形成最终产物Ti3SiC2.     

活性填料对聚碳硅烷基悬浮液直写成形3D碳化硅的影响

分别采用纳米钛粉(Ti)和氧化亚镍粉(NiO)为活性填料,聚碳硅烷(polycarbosilane,PCS)为碳化硅(SiC)陶瓷先驱体,以正己烷作为溶剂制备浆料,然后通过3D直写成形和高温裂解制备SiC陶瓷基复合材料,对浆料的流变性能以及SiC陶瓷基复合材料的物相和微观形貌进行表征,研究活性填料纳米Ti粉和纳米NiO粉对3D-SiC陶瓷基复合材料的物相与微观形貌的影响。结果表明,浆料的黏度与PCS的质量分数成正比,具有剪切变稀现象,w(PCS)为75%的浆料具有稳定的打印性能。纳米Ti粉可有效降低成形坯体热处理过程中的质量损失率和线收缩率。随m(Ti)/m(PCS)的值从0增加到1.0,1 450℃高温裂解后陶瓷的质量损失率和线收缩率分别由18.29%和24.38%降低至14.05%和12.13%,所得陶瓷包含Ti C和SiC两相,相比于Ti粉,NiO可作为SiC的表面修饰催化剂,并通过气-液-固(V-L-S)生长机制使SiC陶瓷表面原位生长SiC晶须团簇。     

放电等离子烧结Ti/(1-x)Ti_3SiC_2+xSiC层状材料的显微结构

以钛粉,硅粉和石墨粉为原料,采用放电等离子烧结技术制备密度为4.14 g/cm3的Ti3SiC2和密度为4.03 g/cm3的0.8 Ti3SiC2+0.2 SiC复合材料,并以此为基础制备Ti/Ti3SiC2/0.8Ti3SiC2+0.2SiC层状材料。通过扫描电镜(SEM)和X射线衍射仪(XRD)分析材料的显微结构与相组成。结果表明:该层状材料的界面结合紧密,没有明显的孔洞、裂纹等缺陷,各层的相组成符合设计要求。经800℃热处理40 h后Ti/Ti3SiC2界面处生成稳定的TiC层,在高温下该层状材料的界面基本稳定。     

热压法制备Ti3SiC2陶瓷结合剂/金刚石复合材料的组织结构

以Ti、Si、C粉、金刚石磨料为原料,添加适量Al粉,采用热压法制备Ti3SiC2陶瓷结合剂/金刚石复合材料,通过X射线衍射、扫描电镜及能谱分析对该复合材料的组织结构进行观察与分析,并研究烧结温度、助熔剂 Al 含量以及金刚石浓度对复合材料的影响。结果表明,因金刚石的反应活性较差,较低温度下热压时金刚石表面未能生长出Ti3SiC2,1300℃高温下热压形成的Ti3SiC2晶粒发育良好;适量添加Al粉有助于Ti3SiC2的合成;金刚石颗粒浓度从25%增加到50%时,金刚石参与并促进Ti3SiC2的合成,Ti3SiC2含量明显增加;金刚石表面生成晶型发育良好的Ti3SiC2晶粒,实现了磨料与结合剂的化学键合,从而提高结合剂与磨料间的结合力。     

Pd基活性钎料对SiC陶瓷的润湿研究

为研究Pd基钎料钎焊SiC陶瓷与其他材料的接合机制,研究了PdAgMn＋Ti钎料对SiC陶瓷的润湿规律,发现元素Ti显著影响钎料对SiC陶瓷的润湿性。通过X射线衍射仪对润湿界面进行了观察,发现在钎料与SiC润湿界面存在Pd和Si的化合物Pd100-xSix以及TiC。说明PdAgMn＋Ti能够润湿SiC陶瓷,并与SiC陶瓷形成冶金结合。用PdAgMn钎料对两种SiC样品在同样温度条件下作了高真空,低真空润湿试验。一种是在高真空中处理的涂Ti的SiC样品;另一种是不涂Ti的SiC样品。结果在高真空和低真空两种试验条件下,PdAgMn钎料对高温处理的涂Ti的SiC样品均润湿良好,而对不涂Ti的SiC样品不润湿。实验结果说明PdAgMn合金对涂Ti的SiC样品表面的润湿其实就是对TiC表面的润湿,TiC的形成是Pd合金润湿SiC陶瓷的必要条件。     

Ti—Si—C三元体系自蔓延高温合成的反应热力学研究

根据热力学原理对Ti-Si-C三元体系进行了热力学计算分析,计算了Ti3SiC2自蔓延高温合成的绝热温度,绘出了体系各反应产物的反应自由焓ΔG与反应温度T的关系曲线,并测量了Ti3SiC2自蔓延高温合成的实际燃烧温度.研究结果表明:Ti-Si-C三元体系在SHS反应过程中其燃烧波能够自发进行;在SHS反应的高温区域,反应产物的热力学稳定性从高到低依次为Ti3SiC2、SiC、TiC,TiC和SiC有向Ti3SiC2反应转化的趋势;Ti3SiC2的SHS反应实际燃烧温度低于其理论绝热温度,主要原因是实际进行的SHS反应存在热量损失所致.     

SiC晶须增韧WC陶瓷刀具材料的研究

通过正交试验法对WC／SiCw陶瓷复合材料进行了成分和热压工艺参数优化，经优化制备的该类复合材料与纯WC材料相比，抗弯强度提高了约50％，断裂韧性提高了30％～40％，维氏硬度提高了10％～15％。切削试验数据证明，本试验制得的WC／SiCw复合陶瓷刀具材料的车削性能优于同类型硬质合金材料，表明通过SiCw替代金属粘结相来增韧补强WC陶瓷刀具材料的方法是可行的。     

Synthesis and Property of H2La2Ti3O10/CdS Layered Nanocomposite Photocatalyst

H2La2Ti3O10/CdS nanocomposite with er photoactivity was synthesized by a stepwise exchange process from H2La2Ti3O10, which was obtained by H^＋ -exchanging reaction of H2La2Ti3O10 with HCl other than the normally used HNO3. The pillaring process was investigated by XRD, TEM, FT-IR and BET methods. The photocatalytic decomposition of aniline was used as the model system to evaluate the photochemical properties of H2La2Ti3O10/CdS,H2La2Ti3O10 and K2La2Ti3O10. It is found that the photoactivity of layered H2La2Ti3O10 is greatly improved by the intercalation of CdS in the interlayer. In general, the excellent photoactivity of the H2La2Ti3O10/CdS nanocomposite might be attributing to the extremely small particle size of incorporated CdS and good contact between CdS and La2Ti3O10^2- layers. On the other hand, the coupling of two semiconductor particles with different energy gap is useful to achieve effective charge separation. In H2La2Ti3O10/CdS, a photo-generated electron can transfer from CdS to the La2Ti3O10^2- layer, while the holes remain in the CdS particles. This helps to diffuse the electrons and holes before reaching the interface, and the holes and electrons can be effectively captured by the electrolyte in the solution. Simuhaneously, the optimal operating condition of photodecomposition aniline was investigated.     

Physicochemical Processes of Fabricating Ceramic Materials Based on Nanopowders of Zirconium,Yttrium, Cerium,and Aluminum Oxides

When studying nanoceramics, it is necessary to constantly keep in mind the closest interrelation of their fabrication method, structure, and properties. Nanoceramic materials are used in various branches of technology as structural and functional materials. Nanoceramics are also widely used in medicine. They are harmless, stable, and have great affinity to living organisms. ZrO2-based nanoceramics have a lower elastic modulus than other oxide materials. The specificity of their application lies in their high rupture strength, thermal shock resistance, and chemical stability at high temperatures. However, it is necessary to solve the problem of increasing the fracture toughness of ZrO2-based ceramic materials. The complex alloying of ZrO2 with yttrium and cerium oxides and the use of the Al2O3 additive leads to an increase in the fracture toughness and lowering of the negative effect of materials in the biological medium. In this work, the physicochemical properties of ceramic powders and materials of the ZrO2–2Y2O3–4CeO2–Al2O3 system synthesized by the chemical deposition of inorganic precursors when applying the sol-gel technology are considered based on scientific data and experimental studies. Alloying pure zirconium oxide by stabilizing Y2O3 and CeO2 oxides and thermal hardening of Al2O3 ensure the conservation of the tetragonal structure at room temperature, which makes it possible to retard and control the crack resistance of the material under the load. Investigations into the influence of the sintering temperature and aluminum oxide content on the microstructure and grain size, as well as physicomechanical properties of ceramic materials of compositions ZrO2–2Y2O3–4CeO2 + 1 wt % Al2O3 and ZrO2–2Y2O3–4CeO2 + 3 wt % Al2O3, are carried out.     

LaMgAl11O19-La2Ce2O7 复合陶瓷的高温相稳定性

La2Ce2O7(LC) 和 LaMgAl11O19(LMA) 是两种新型热障涂层材料。 LC 具有优良的热物理及抗腐蚀性能, 但 其断裂韧性差。 LMA 具有良好的综合性能, 特别是力学性能优良。 基于复合材料设计理念, 为充分利用 LC 和 LMA 的优势, 本文探究了制备 LMA-LC 双相复合陶瓷的可行性。 采用高温固相法合成了 LMA 和 LC 粉末, 重 点研究了 LMA 和 LC 的高温稳定性, 初步研究了 LMA-LC 复合陶瓷块材的力学性能。 结果表明： LMA 和 LC 在 高温下发生了化学反应, 反应程度随温度升高而加剧, 主要反应产物为 LaAlO3, 其在低温下的铁弹性可能是复 合陶瓷在室温下具有良好力学性能的原因。     

高导热氮化铝陶瓷的粉末注射成形技术

氮化铝(AlN)陶瓷具有热导率高、热膨胀系数低、电阻率高等特性以及良好的力学性能,被认为是新一代高性能陶瓷基片和封装的首选材料,为了满足微电子技术发展对微型复杂形状高导热陶瓷零部件用量日益增加的需求,该文作者研究利用粉末注射成形技术制备高导热AlN陶瓷零部件.该技术以AlN粉末为原料,加入5%Y2O3为烧结助剂;选用蜡基粘结剂体系(PW+PP+SA),确定粉末装载量为62%(体积分数),注射温度为160～170℃,注射压力为90～100 MPa;采用溶剂脱脂+热脱脂工艺脱脂;在1850℃流动氮气氛中烧结.所制备出的AIN陶瓷热导率达232.4 W/(m·K).     

CeO2对不锈钢基SiO2-BaO-Al2O3-Cr2O3陶瓷涂层性能的影响

采用高温熔烧法于1Cr18Ni9Ti不锈钢基材表面制备掺CeO2的SiO2-BaO-Al2O3-Cr2O3陶瓷涂层,研究了不同含量CeO2对涂层的抗氧化性、抗热震性和硬度的影响。研究结果表明,含CeO2的不锈钢基SiO2-BaO-Al2O3-Cr2O3陶瓷涂层能有效阻止不锈钢基体的氧化增重,提高涂层的抗热震性能及硬度。本实验条件下,CeO2含量2.8%时,涂层具有最好的抗氧化性能和抗热震性能。     

离心自蔓延高温合成陶瓷内衬复合钢管的研究与应用

应用自蔓延高温合成技术和离心技术，制造了陶瓷内衬复合钢管，并分析了其制造原理，测试了其性能，复合钢管陶瓷层硬度高、耐磨性好，但孔隙率高，韧性低。在铝热剂中加入SiO2，可提高致密度，改善耐蚀性，加入ZrO2可提高断裂韧性。它应用于矿山输送矿浆管道上，使用效果很好。     

Methods of Increasing the Thermal Resistance of Articles Made from Ceramic with Two-Sided Protective Coating

The influence of the size and shape of the parts of containers made of laminar ceramic on the thermal resistance of containers is qualitatively estimated. The coefficient in the estimation formula for thermal resistance which expresses the influence of shape and size on the thermal resistance of manufactured articles is broken down into several factors. These factors depend on the properties, shape, and size of the ceramic base and coating and the boundary between them. A model that shows how to reduce the influence of the individual factors in the thermal resistance formula on the thermal resistance of the entire article is proposed. A method of reducing this influence by soldering articles from individual parts of simplified shape is developed. Comparative tests of vessels made of quartz ceramic with a protective coating of Nb₂O₅ and assembled according to the proposed method were conducted. Qualitative observations of acoustic emission in the cooling process demonstrated that based on the proposed model, a substantial increase in the thermal resistance of vessels can be achieved by manufacturing the vessels from laminar ceramic.__________Translated from Poroshkaya Metallurgiya, Nos. 3–4(442), pp. 49–54, March–April, 2005.     

添加Al2O3--ZrO2复合粉改性氧化锆质定径水口及其损毁机理

通过添加溶胶-凝胶法制备的Al₂O₃-ZrO₂复合粉,对陶瓷型和颗粒型氧化锆质定径水口进行改性.对比研究了陶瓷型和颗粒型定径水口改性前后物理性能,矿物相组成和显微结构的变化,并通过现场连铸实验对四种定径水口损毁机理进行了探讨.结果表明:相较于颗粒型定径水口,陶瓷型定径水口的显气孔率较低,体积密度和耐压强度较高,热震稳定性较差,抗侵蚀和冲刷性能较好.通过添加Al₂O₃-ZrO₂复合粉改性后的定径水口显气孔率降低,体积密度增加,耐压强度提高,颗粒型定径水口的热震稳定性有了较大的提升,热震次数约为改性前的1.5倍以上.通过对连铸现场实际使用35 h后的残样分析发现,陶瓷型水口损毁主要是由于热震稳定性差导致使用时发生炸裂,炸裂产生的裂纹引起一定程度的剥落和扩径.未改性颗粒型定径水口由于强度低和显气孔率高,剥落和扩径更为严重,添加Al₂O₃-ZrO₂复合粉改性后生成的镁铝尖晶石增强相大幅度提高了颗粒水口的热震稳定性和抗冲刷侵蚀性能,连铸现场使用后几乎未扩径.      

Laser cladding in-situ carbide particle reinforced Fe-based composite coatings with rare earth oxide addition

Particulate reinforced metal matrix composite(PR-MMC) has excellent properties such as good wear resistance,corrosion resistance and high temperature properties.Laser cladding is usually used to form PR-MMC on metal surface with various volume fractions of ceramic particles.Recent literatures showed that laser melting of powder mixture containing carbon and carbide-forming elements,was favorable for the formation of in-situ synthesized carbide particles.In this paper,rare earth oxide(RE2O3) was added into t...