SiC/Si_3N_4陶瓷前驱体的合成

通过在六甲基环三硅氮烷中加入部分甲基氢二氯硅烷的氨解产物 (CH3 HSiNH )x ,经氢化钾催化制备了聚硅氮烷 ;用热重分析法研究了其裂解性能 ,考察了反应原料比例、溶剂对陶瓷产率的影响 ;结果表明 :溶剂和原料比例不仅影响聚硅氮烷的性能 ,且对陶瓷产率有重要影响。以四氢呋喃做溶剂可得到较高的陶瓷产率。     

采用有机前驱体制备Si3N4／SiC纳米复相陶瓷

本研究采用有机前驱体为主要原料，通过热解及烧结制备了两类Ｓｉ３Ｎ４／ＳｉＣ纳米复相陶瓷，研究了这些材料的微结构特点，讨论了材料强化的机制及力学性能与显微结构的关系。     

Si3N4／纳米SiC复相陶瓷显微结构的研究

本研究通过采用纳米SiC粉体及有机前驱体两种途径,制备了Si_3N_4/纳米SiC粒子(Si_3N_4/纳米SiCp)复相陶瓷,研究了这些材料的显微结构特点,讨论了材料强化的机制与显微结构的关系。     

用有机前驱体制备Si3N4／纳米SiC复相陶瓷的研究

本研究成功地用有机前驱体引入纳米ＳｉＣ粒子制备出Ｓｉ３Ｎ４／纳米ＳｉＣｐ复相陶瓷。研究了制备工艺和有机前驱体加入量对材料性能及显著结构的影响，并对材料显微结构特点与强韧化机制进行了分析讨论。     

Si3N4—SiC系复合陶瓷的试制

1.前言随着现代化学工业的飞速发展多种防腐蚀材料相继脱颖而出,应用于化学工业设备。具有一定耐腐蚀性能的普通化工陶瓷,由于存在着气孔率高、机械强度低和热稳定性差等缺     

SiC和Si3N4纳米陶瓷粉体备技术

纳米材料科学是近年来兴起的新的科学领域，纳米粉体的制备则是纳米材料研究的主要方面。本文比较详细地介绍了制备碳化物、氮化物纳米陶瓷粉体的四种主要工艺：热化学气相反应法、激光诱导化学气相沉积法、等离子气相合成法和溶胶－凝胶法。对于目前碳化物、氮化物纳米陶瓷粉体的制备工艺和目前水平作了一个总体概括。     

Si-C-N陶瓷前驱体聚硅氮烷合成的研究进展

综述了合成Si—C—N陶瓷前驱体聚硅氮烷的主要方法，即氨／Q解氯硅烷法、硅氮烷低聚物交联法、硅氮烷低聚物与氯硅烷反应法及氯硅氯烷和氯硅烷脱氯编聚法，并介绍了用铝、硼、钛、钇等元素对聚硅氮烷进行改性，以提高Si—C—N陶瓷性能的方法。     

Si3N4／SiC纳米复相陶瓷研究进展

本文综述了Ｓｉ３Ｎ４／ＳｉＣ纳米复相陶瓷的研究进展,较详细地介绍了纳米粉体的制备工艺及热处理研究、复相陶瓷的制备工艺、力学性能、微观结构及增韧强化机理。     

Si3N4／纳米SiC复相陶瓷的研究

采用纳米ＳｉＣ粉体制备了Ｓｉ３Ｎ４／纳米ＳｉＣｐ复相陶瓷。研究了制备工艺、纳米ＳｉＣ含量对材料性能及显微结构的影响,并对材料显微结构特点与强韧化机制进行了分析 。结果表明：添加２０ｖｏ％〈１００ｎｍ的ＳｉＣ粉体时,复相陶瓷的室温抗弯强度达８５６ＭＰａ,当添加１０ｖｏ％上述ＳｉＣ粉体时,复相陶瓷的增韧效果最佳,断裂韧性达８．２７ＭＰａｍ＾１／２,比基体材料提高了２３％。     

Porous Si3N4/SiC Ceramics Prepared via Nitridation of Si Powder with SiC Addition

Porous Si₃N₄/SiC ceramics with high porosity were prepared via nitridation of Si powder, using SiC as the second phase and Y₂O₃ as sintering additive. With increasing SiC addition, porous Si₃N₄/SiC ceramics showed high porosity, low flexural strength, and decreased grain size. However, the sample with 20wt% SiC addition showed highest flexural strength and lowest porosity. Porous Si₃N₄/SiC ceramics with a porosity of 36–45% and a flexural strength of 107‐46MPa were obtained. The linear shrinkage of all porous Si₃N₄/SiC ceramics is below 0.42%. This study reveals that the nitridation route is a promising way to prepare porous Si₃N₄/SiC ceramics with favorable flexural strength, high porosity, and low linear shrinkage.     

Synthesis of Si3N4/SiC reaction-bonded SiC refractories: The effects of Si/C molar ratio on microstructure and properties

Si₃N₄/SiC reaction-bonded SiC refractories have been fabricated on the basis of the microstructure design concept by introducing a binary-phases binding system. The influence of Si/C molar ratio on phase transformation, microstructure and mechanical properties was studied systematically. Thermodynamic analysis result proved the microstructure design was feasible under 0.03 MPa pressure of N₂ and the selected sintering temperature. In-situ grown SiC nano-whiskers/granule and lamellar Si₃N₄ were both observed in the matrix. The specimen with 2:1 Si/C molar ratio possessed highest cold modulus of rupture (28.27 MPa) but showed low toughness. The strength and toughness of such materials were controlled by two main factors, such as SiC grain boundary binding morphology and in situ grown of SiC in the matrix. The different mechanisms occurred predominantly to meet diverse practical cases and caused to various mechanical properties of final products. The corresponding strengthening and toughening mechanisms were explained in this paper.     

Effect of long-term oxidation on creep and failure of Si3N4 and Si3N4/SiC nanocomposites

The high-temperature mechanical behaviour of an Si₃N₄/SiC nanocomposite and its monolithic Si₃N₄ reference material was studied after long-term oxidation treatments intended to simulate future operating conditions in a severe environment. Creep and failure at elevated temperature were significantly affected, in the direction of increased brittleness. The transition stress between the ductile range present at low stresses and the brittle range existing at high stresses was shifted to distinctly lower values. The creep resistance in the low-stress range was increased by the oxidation treatment. The failure time under a given stress was drastically reduced; this was attributed to an increased sensitivity to subcritical crack growth. The failure stress for a given failure time was decreased by about half. The phenomena are explained in terms of a purification of the intergranular phase and by the formation of surface defects and of a uniformly distributed pore population.     

SiC原料颗粒级配对Si3N4结合SiC复合陶瓷材料的影响

采用SiC粉和Si粉高温氮化反应烧结制备Si3N4结合SiC复合陶瓷材料。研究四种SiC原料粉体(0-1mm、74μm、44μm、和0.5μm)中三种不同粒度不同含量颗粒级配对Si3N4结合SiC复合陶瓷材料的影响。通过X射线衍射仪和扫描电子显微镜对试样的物相和显微结构进行表征,并对试样的耐压强度等力学性能进行测试。结果表明:采用三种SiC较细粉体颗级配且如下组成:74μm的含量为5 wt%,44μm的含量为10 wt%,0.5μm的含量为35 wt%,所制备的Si3N4结合SiC陶瓷材料的基本烧结性能较好,其体积密度为2.43g/cm3,耐压强度为324MPa。     

利用硅废料燃烧合成碳化硅/氮化硅复合粉体

对在太阳能等行业生产过程中产生的硅废料进行回收或重复利用具有重要的经济价值,但目前的回收方法普遍存在成本较高等问题.本文利用商业硅粉和硅废料为原料,通过高温自蔓延合成方法合成复合Si3N4/SiC陶瓷粉体.结果显示产物的显微形貌与原料配比和氮气压力有较大关系.随着氮气压力的升高,β-Si3N4的比例增加.在较低温度的临界状态下,会形成片状Si3 N4晶体.     

反应烧结形成氮化硅/碳化硅材料

介绍了反应烧结形成氮化硅／碳化硅材料的制备工艺，对该材料的微观结构、性能及其影响因素进行了阐述，并介绍了该材料的应用背景。