用Al-Ti和Al-Zr合金在大气中连接Si3N4陶瓷

用Al-Ti和Al-Zr合金成功地在大气中连接了Si3N4陶瓷,结果表明,适当加压能防止Al-Ti和Al-Zr合金的氧化;连接时间、连接温度和合金中的Ti、Zr含量明显影响接头强度;用Al-Ti和Al-Zr合金连接Si3N4陶瓷时,Al和Ti或Al和Zr同时与Si3N4陶瓷反应形成界面反应层,强化了接头。     

Cu—Nu—Ti合金钎料对Si3N4陶瓷的润湿与连接

采用座滴法研究了Ｃｕ－Ｎｉ－（２７－５６）Ｔｉ合金（原子分数,％,下同）在Ｓｉ３Ｎ４陶瓷上的润湿行为。选用真空熔炼合金Ｃｕ３８Ｎｉ３０Ｔｉ３２和Ｃｕ３４Ｎｉ２７Ｔｉ３９作为钎料时,获得的Ｓｉ３Ｎ４／Ｓｉ３Ｎ４接头的强度不理想。     

SiC陶瓷与TiAl合金的真空钎焊

采用Ａｇ－Ｃｕ－Ｔｉ钎料对常压烧结的ＳｉＣ陶瓷与ＴｉＡｌ金属间化合物进行了真空钎焊,并对接头的微观组织和室温强度进行了研究。结果表明,利用Ａｇ－Ｃｕ－Ｔｉ钎料可以实现ＳｉＣ与ＴｉＡｌ的连接;接头界面具有明显的层状结构,即由Ｔｉ－Ｓｉ合金层、富Ｃｕ相与富Ａｇ相的双相层和Ｔｉ－Ａｌ－Ｃｕ合金层组成;在１１７３Ｋ和１０ｍｉｎ的钎焊条件下,接头室温剪切强度达互１７３ＭＰａ。     

加载方式对Si3N4陶瓷疲劳特性的影响

系统研究了加载方式(静载荷、循环载荷、动载荷)对Si3N4陶瓷疲劳特性的影响。结果发现，加载方式不同，材料的应力腐蚀指数n亦不相同，其中，静载下n最大，动载荷次之，循环载荷下n最小，并分析了循环载荷及动载荷对材料造成的附加损伤。     

钎焊温度对Ti60合金与Si3N4陶瓷接头界面组织及性能的影响

为研究钎焊温度对Ti60/Si₃N₄接头组织与力学性能的影响,采用Ag-28Cu共晶钎料在870~910℃温度区间,保温10 min条件下进行钎焊连接.利用扫描电子显微镜、能谱仪对钎焊接头界面组织进行分析,得到的典型接头界面组织结构为Ti60/Ti-Cu化合物/Ag（s,s）+Cu（s,s）/Ti-Cu化合物/Ti₅Si₃+TiN/Si₃N₄,并对钎焊接头的组织演变过程进行了分析.结果表明,随着钎焊温度的升高,Ti60侧的Ti-Cu化合物反应层与Si₃N₄陶瓷侧的Ti₅Si₃+TiN反应层厚度逐渐增加,Ag（s,s）与Cu（s,s）含量减少,同时,扩散至Si₃N₄陶瓷侧的Ti元素与液相中Cu元素反应生成Ti-Cu化合物并在Ti₅Si₃+TiN反应层中形核.剪切测试表明,在钎焊温度880℃,保温10 min工艺参数条件下获得的接头最大抗剪强度为61.7 MPa.     

一种钎焊Si3N4陶瓷的高温非晶钎料

此发明属于钎焊材料技术领域。涉及一种钎焊Si3N4陶瓷的高温非晶钎料,更具体地说是涉及一种Ti-ZrCu-B高温活性非晶钎料。     

Ni-Sn-Ti合金钎料对Si3N4陶瓷的润湿性研究

采用一系列Ni-20Sn-xTi合金钎料进行了Si3N4/Si3N4真空钎焊连接研究.结果表明:Ni-20Sn-10Ti合金钎料对Si3N4陶瓷具有最好的润湿性,同时能够有效地提高接头的连接强度.     

Si3N4陶瓷连接技术研究进展

Si3N4陶瓷的连接技术作为其广泛使用的重要前提,受到了国内外学者的广泛关注.文中概述了近年来国内外几种Si3N4陶瓷与自身及其它金属材料的连接技术,涉及的连接方法包括活性金属钎焊、固相扩散连接、瞬时液相扩散连接和玻璃焊接,重点介绍了Si3N4陶瓷连接时的接头界面结构、连接机理及接头质量.     

激光熔覆Si3N4陶瓷层的微观结构研究

介绍了用横流式ＣＯ２激光器在Ｘ６０ＣｒＭｎＭｏＶＮｂＮ２１１０钢表面熔覆Ｓｉ３Ｎ４陶瓷的方法。用透射电镜和光学显微镜熔覆层内相组成及界面结构。结果表明，熔覆层内Ｓｉ３Ｎ４或ＷＣ颗粒与粘结相Ｃｏ形成包裹结构，各相结合致密，且与基材形成了冶金结合。其主要组成相为α－Ｓｉ３Ｎ４，β－Ｓｉ３Ｎ４，ＷＣ和Ｃｏ，Ｓｉ３Ｎ４在α→β相转变时，形成非周期性的反相畴结构。性能测定指出，熔覆层具有较高的硬度（１６００     

含Ti活性钎料钎焊Si3N4陶瓷时的前驱膜现象

在研究Ag-Cu-Ti、Cu-Ni-Ti活性钎料对SiN4陶瓷浸润性的铺展性试验中，发现在钎料铺展前沿存在一圈前驱膜。试验结果表明：Ag-Cu-Ti钎料的前驱膜宽度很窄，而Cu-Ni-Ti钎料的浸润性与前驱膜宽度有较好的对应关系，浸润性改善时，前驱膜宽度也随之增加。     

Ti-Zr-Ni-Cu非晶钎料钎焊Si3N4陶瓷的连接强度

采用Ti40Zr25Ni15Cu20非晶钎料钎焊Si3N4陶瓷,研究钎焊工艺参数对界面反应层和接头连接强度的影响。结果表明:随着钎焊时间的增加和钎焊温度的提高,接头弯曲强度都表现出先上升后下降的趋势;钎焊工艺参数对连接强度的影响主要是由于影响反应层厚度所致;在相同钎焊工艺条件下,采用Ti40Zr25Ni15Cu20非晶态钎料和晶态钎料相比,其接头连接强度提高了84%。     

Preparation of Si3N4-TaC and Si3N4-ZrC composite ceramics and their mechanical properties

Si₃N₄-TaC and Si₃N₄-ZrC composite ceramics with sintering additives were consolidated in the sintering temperature range of 1500–1600 °C using a resistance-heated hot-pressing technique. The addition of 20–40 mol% carbide improved the sinterability of the ceramics. The ceramics were densely sintered under 0–40 mol% TaC or ZrC at 1500 °C, 0–80 mol% TaC at 1600 °C, and 0–60 mol% ZrC at 1600 °C. In ceramics sintered at 1500 °C, the proportion of α-Si₃N₄ was larger than that of β-SiAlON; α-Si₃N₄ transformed mostly to β-SiAlON at 1600 °C. Carbide addition was effective in inhibiting α-Si₃N₄-to-β-SiAlON phase transformation. Young's modulus for the dense Si₃N₄-TaC and Si₃N₄-ZrC ceramics increased with the carbide amount, and the hardness of dense Si₃N₄-ZrC and Si₃N₄-TaC ceramics increased from 14 GPa to 17 GPa with increasing α-Si₃N₄ content. Dense Si₃N₄-TaC and Si₃N₄-ZrC ceramics, with larger quantities of α-Si₃N₄ sintered at 1500 °C, exhibited high hardness; the fracture toughness of these ceramics decreased with increasing α-Si₃N₄ proportion. Both the hardness and fracture toughness of the dense Si₃N₄-TaC and Si₃N₄-ZrC ceramics were strongly related to the proportion of α-Si₃N₄ in the sintered body.     

Processing and characterization of sintered reaction bonded Si3N4 ceramics

The present contribution reports the influence of nitridation and sintering conditions on the densification, microstructure, mechanical and thermal conductivity properties of sintered reaction bonded Si₃N₄ (SRBSN) mixed with 3.5% Y₂O₃-1.5% MgO. The nitridation of samples was carried out at 1450 and 1500 °C for different time schedules (2.5, 8 and 16 h) in order to increase β Si₃N₄ phase and subsequently sintering was performed at various temperatures (1850, 1900 and 1950 °C) for 10 h to enhance densification and properties of SRBSN ceramics. It was observed that the density of the samples slightly decreased and β Si₃N₄ phase significantly increased to 87% with increasing nitridation temperature and time. The density of gas pressure sintered (GPS) samples increased with increasing sintering temperature, almost full density was measured for all the samples at the respective sintering temperature (except those samples which were given nitridation at 1500 °C for 16 h). The microstructure of SRBSN samples were characterized by bimodal microstructure with equiaxed and rod like elongated grains and average grain size of SRBSN samples varied between 1.62 and 2.43 μm and aspect ratio of grains varied from 3.78 to 6.88 with varying the sintering temperature. Depending on the sintering density and microstructure, the SRBSN samples exhibited hardness (16.69 to 19.47 GPa), fracture toughness (7.02 to 9.20 MPa·m^1/2) and thermal conductivity (77.32 to 98.52 W/m·K). The coarsening of grain size and aspect ratio negatively affected hardness and fracture toughness, on the contrary the thermal conductivity increased. Among all samples, the SRBSN (which was subjected to nitridation at 1500 °C for 16 h; GPS at 1950 °C for 10 h) measured with good combination of hardness: 17.32 GPa, fracture toughness: 8.36 MPa·m^1/2and thermal conductivity: 98.52 W/m·K.     

Microstructure of reactive sintered Al bonded Si3N4-SiC ceramics

Aluminium nitride-silicon nitride-silicon carbide （AIN-Si3N4-SiC） composite ceramics were prepared to increase the bending strength and improve the phase structure of Si3N4-based ceramics. The ceramics were made by reactive sintering in N2 atmosphere at 1 360 ℃, using Al as sintering additive. The phase composing of ceramics was identified with an X-ray diffractometer and the microstructure of the materials was studied by scanning electron microscopy. The results indicate that the phase structure is affected remarkably and the interface modality is changed. The interface between Si3N4 and SiC becomes blurry and that between SiC and AlN matches more better at the same time. But the liquid-phase appears during the reactive sintering along with the addition of AI by which the melting point of Si is decreased. The appearance of liquid Si decreases the bending strength of the ceramics. Lower temperature nitrification technic was introduced to avoid the appearance of liquid-phase Si. The optimum addition of Al was investigated by XRD and SEM analysis in order to obtain the maximal bending strength of materials.     

Ti-Zr-Ni-Cu非晶钎料在Si3N4陶瓷上的润湿性研究

针对Si3N4陶瓷的高温活性钎焊要求,设计了高温Ti-Zr-Ni-Cu非晶钎料成分,并采用单辊急冷法成功制备了Ti-Zr-Ni-Cu非晶钎料.对比分析了相同成分的Ti-Zr-Ni-Cu非晶和晶态钎料在Si3N4陶瓷表面的润湿情况.结果表明:在低真空条件下,晶态钎料能够润湿Si3N4陶瓷,非晶钎料却因完全氧化而失效.在5×10-3Pa高真空条件下,非晶钎料的润湿性优于晶态钎料,在研究的Ti-Zr-Ni-Cu非晶钎料中,Ti40Zr25Ni15Cu20非晶钎料对Si3N4陶瓷的润湿性最佳.     

Ag—Cu—Ti急冷钎料在Si3N4陶瓷上的润湿性研究

采用单辊急冷装置成功制备了3种成分的Ag-Cu-Ti箔带钎料,分析了其熔化特性和结构及其在Si3N4陶瓷上的润湿性.试验结果表明:上述急冷箔带钎料与常规钎料相比,熔化温度更低,熔化温度区间更窄,但其结构并不是非晶;在相同的工艺条件下,(Ag72Cu28)96Ti4在Si3N4陶瓷上的润湿性最佳;随钎焊温度和保温时间的增加,Ag-Cu-Ti急冷和常规钎料在Si3N4陶瓷上的浸润面积均增大;在相同钎焊工艺条件下,同成分急冷钎料在Si3N4陶瓷上的铺展面积明显大于常规钎料,这是由于急冷钎料的熔化特性和结构不同所导致的.