水润滑下陶瓷与灰铸铁副的滑动磨损特性

研究了在蒸馏水润滑下Si3N4、Al2O3陶瓷与灰铸铁副的摩擦磨损特性。结果表明：Al2O3陶瓷的磨损体积损失远小于Si3N4的,但灰铸铁与Si3N4配副时的磨损体积损失却大大小于与Al2O3配副时的,其摩擦系数也很小（0．02）。用SEM观察磨损形貌,发现灰铸铁与Si3N4配副时Si3N4磨面极其光滑,与其对应的灰铸铁磨面上存在含石墨的润滑膜。     

Si_3N_4的结构状态对放电等离子烧结制备Sialon陶瓷的影响

以纳米非晶-Si3N4、微米α-Si3N4、微米AlN、纳米Al2O3和纳米Y2O3为初始原料,采用放电等离子烧结工艺制备了Sialon陶瓷。通过调整配方中Si3N4对应原料的种类,研究了不同结构的Si3N4对合成Sialon陶瓷的影响。通过XRD和SEM对试样的物相和显微结构进行了表征,同时测试了试样的体积密度、抗弯强度、断裂韧性和维氏硬度。实验结果表明,配方中的Si3N4全部采用α-Si3N4,经SPS烧结后可获得α/β-Sialon陶瓷,当用纳米非晶-Si3N4逐步替换α-Si3N4时,所合成的Sialon陶瓷中的α-Sialon晶相的相对含量减少;当全部采用纳米非晶-Si3N4时,则试样中仅含有β-Sialon相。     

聚氮硅烷催化裂解原位合成碳纳米管增强SiC/Si_3N_4复相陶瓷

以聚氮硅烷为前驱体,通过催化裂解原位生成SiC/Si3N4复相陶瓷,同时原位生成碳纳米管增韧相;研究热解温度、掺杂催化剂种类对SiC/Si3N4复相陶瓷微观结构及形态的影响,运用扫描电镜、高分辨率透射电镜、X射线衍射、综合热分析进行结构分析和表征。结果表明,催化裂解可有效增强陶瓷基体的强度和实现基体与纳米相的复合和分散,并降低SiC/Si3N4复相陶瓷晶化温度。     

颗粒污染条件下Si3N4陶瓷球疲劳行为的试验研究

定量研究了颗粒污染对Si3N4陶瓷球滚动接触疲劳寿命的影响，并分析比较了在清洁的润滑油润滑和颗粒污染油润滑的条件下Si3N4陶瓷球动接触疲劳的形成机理。     

Sialon陶瓷的常压烧结

在Si3N4,Al2O3,AIN和Y2O3混合料常压烧结过程中,由于过程反应生成SiO,CO,N2等气相物质和由于Si3N4原料在高温常压下分解压高,从而常压烧结致密化过程始终伴随着一个失重的塑致密化过程。为了解决这一问题,作者研究了填料成分、烧结温度、烧结时间等工艺条件对Sialon陶瓷常压烧结密度的影响,分析了烧结过程的物理化学机制和致密化机制。4种填料分别为Si3N4,Si3N4 SiO2,Si3N4 Al2O3 AIN和Si3N4 Al2O3 AIN BN。被烧料典型配方为：Si3N465%-70%,Al2O320%-25%,AIN10%,另加6％Y2O3。当填料成分为70％Si3N4 24%Al2O3 3%AIN 3%BN时,制得了相对密度达99％,抗弯强度达612．2MPa的常压烧结Sialon陶瓷。研究结果表明：对于通式为Si6-zAlzOzN8-z的Sialon陶瓷,当Z＝2时,其最佳烧结温度为1750℃,烧结时间为40min;Sialon的烧结过程是1个多因素控制的瞬时液相烧结过程。     

聚氨酯陶瓷复合材料浆体磨损性能研究

用聚四氢呋喃醚二醇与甲苯二异氰酸酯反应后,分别与Si3N4陶瓷粉、TiO2陶瓷粉末进行共混,制得耐磨蚀聚氨酯/Si3N4和聚氨酯/TiO2陶瓷复合材料,评价了这两种材料的耐磨性,通过扫描电镜观察了复合材料的磨损形貌,探讨了Si3N4和TiO2陶瓷粉末增强聚氨酯弹性体的磨损机理。结果表明:Si3N4粉末在质量分数为10%时,复合材料的耐磨性最好,是2Cr13钢的7.8倍,是45#钢的12.5倍,是纯聚氨酯的1.87倍。当TiO2陶瓷粉末在质量分数为8%时,复合材料的耐磨性最好,聚氨酯/TiO2陶瓷复合材料的抗冲蚀磨损性能分别是2Cr13钢的5.3倍,是45号钢的8.5倍,是纯聚氨酯的1.28倍。陶瓷粉末的加入有效提高了材料的抗冲蚀磨损性。     

Si3N4-SiC太阳能热发电吸热陶瓷的制备及性能

以SiC和Si3N4为主要原料,采用陶瓷制备工艺无压烧结制备了Si3N4-SiC吸热陶瓷材料。采用现代测试技术,测试和分析了烧结样品的烧结收缩率、抗折强度、吸水率、气孔率、体积密度、耐火度、氧化增重率、物相组成以及显微结构。结果表明,最佳配方是1 360℃烧结的D2样品,其Si3N4添加量为20%,抗折强度为79.60 MPa、气孔率为22.23%、吸水率为10.32%、体积密度为2.15g/cm3、耐火度为1 650℃、1 300℃氧化5h后的样品氧化增重率为1.333mg/cm2。XRD和SEM分析表明烧结样品由α-SiC、Si3N4、莫来石和石英组成,Si3N4在样品中呈短棱柱体分布,添加纳米SiC对Si3N4可以起到钉扎作用,阻止Si3N4晶粒长大,从而提高样品的抗折强度和抗热震性能。Si3N4-SiC吸热陶瓷具有高的强度以及良好的微观组织结构,是一种适合塔式太阳能热发电吸热器用吸热材料。     

氮化硅基陶瓷的摩擦磨损特性研究

采用热压烧结方法制备氮化硅和氮化硅基两种陶瓷.利用球-盘式摩擦磨损试验机对氮化硅陶瓷摩擦副在室温干摩擦环境中的摩擦磨损特性试验研究.结果表明在相同的试验条件下,加入TiC颗粒改善了Si3N4陶瓷的脆性,但耐磨性能提高不大,磨损率略优于Si3N4.Si3N4的磨损主要是磨粒磨损和脆性剥落,而TiC复合材料的磨损表现为磨粒磨损和TiC颗粒的剥落,之后剥落的TiC颗粒又作为磨粒对试样产生更大的磨损,所以导致磨损率提高.     

氮化硅基陶瓷的摩擦磨损特性研究

采用热压烧结方法制备氮化硅和氮化硅基两种陶瓷。利用球-盘式摩擦磨损试验机对氮化硅陶瓷摩擦副在室温干摩擦环境中的摩擦磨损特性试验研究。结果表明：在相同的试验条件下,加入TiC颗粒改善了Si3N4陶瓷的脆性,但耐磨性能提高不大,磨损率略优于Si3N4。Si3N4的磨损主要是磨粒磨损和脆性剥落,而TiC复合材料的磨损表现为磨粒磨损和TiC颗粒的剥落,之后剥落的TiC颗粒又作为磨粒对试样产生更大的磨损,所以导致磨损率提高。     

陶瓷与石墨化铸铁副乳化液润滑滑动磨损研究

在室温下,以乳化液为润滑剂,使用环－块磨损试验机进行了Al2O3、ZrO2及Si3N4三种工程陶瓷与球墨铸铁、灰铸铁配副的滑动磨损试验。结果表明陶瓷磨损体积依次增加的顺序为Al2O3→ZrO2→Si3N4,且陶瓷的磨损体积与铸铁的硬度成正比;而铸铁无论与何种陶瓷配副,灰铸铁的磨损体积大于球墨铸铁,马氏体基体铸铁的磨损体积反而大于珠光体基体铸铁。     

合金元素对Si3N4陶瓷生成的影响

以合金元素为添加剂制备氮化硅陶瓷.比较了Ti、Mg、Fe和A l四种合金元素对氮化硅生成的效果,结果表明单一元素Fe的效果比较明显;探讨了Fe含量在0.25%~5%(质量百分数)之间对Si3N4生成的影响,为了避免Fe-Si化合物的生成,Fe的加入量不宜大于1%;对比了复合元素(Fe A l)添加与单一元素(Fe)添加的效果,在添加剂含量相同的条件下,复合元素(Fe A l)比单一元素(Fe)的氮化效果较理想.     

Design,preparation,and structure of particle preforms for Si_3N_(4(P))/Si_3N_4 radome composites prepared using chemical vapor infiltration process

A particle preform was designed and prepared by conglomerating and cold-pressed process,which was condensed by chemical vapor infiltration(CVI)process to fabricate silicon nitride particles reinforced silicon nitride composites.The conglomera- tions are of almost sphericity after conglomerated.There are large pores among the conglomerations and small pores within them- selves in the preform according to the design and the test of pore size distribution.The pore size of the preform is characterized by a double-peak distribution.The pore size distribution is influenced by conglomeration size.Large pores among the conglomerations still exist after infiltrated Si_3N_4 matrix.The conglomerations,however,are very compact.The CVI Si_3N_4 looks like cauliflower- shaped structure.     

高性能Si3N4基可加工复合陶瓷的快速制备

采用SPS在1600～1650℃烧结5min可以获得致密的Si_3N_4-BN复相陶瓷,实验结果表明,随着BN体积分数的增加,BN聚集生长导致Si_3N_4-BN复相陶瓷强度总体均呈缓慢下降趋势,但仍然维持在很高的强度水平,BN体积分数为30%时三点弯曲强度接近900 MPa,而且拥有优异的可加工性能,SEM分析表明,借助SPS可以在实现Si_3N_4-BN复相陶瓷快速致密化基础上进行相组成及显微组织的调控和优化,从而改善材料的性能。     

Microstructure and Dielectric Property of 3D BN_f/Si_3N_4 Fabricated by CVI Process

As potential wave-transparent materials applied at high temperatures, 3D BN_f/Si_3N_4 ceramic matrix composites were prepared by low pressure chemical vapor infiltration or deposition(LPCVI/CVD) process from SiCl_4-NH_3-H_2-Ar gas precursor at 800 oC. The densification process, microstructure and dielectric properties of 3D BN_f/Si_3N_4 composites were investigated. The results indicated that 3D BN_f/Si_3N_4 was successfully fabricated by LPCVI/CVD, with final open porosity of 2.37% and density of 1.89 g/cm~3. Densification kinetics of 3D BN_f/Si_3N_4 is a typical exponential pattern. The Si_3N_4 matrix was uniformly infiltrated into porous BN_f preform. The deposited Si_3N_4 matrix was amorphous by XRD analysis. Introduction of BN fiber into Si_3N_4 ceramic lowered the permittivity of Si_3N_4. The fabricated BN_f/Si_3N_4 composites possess low permittivity of 3.68 and low dielectric loss of lower than 0.01, which are independent of temperature below400 oC. Transmission coefficient of BN_f/Si_3N_4 composite is 0.57 and keeps stable below 400 oC. BN_f/Si_3N_4 can be fabricated at low temperature and may be candidates for the microwave transparent materials.     

Carbon quantum dots: An innovative additive for water lubrication

Water soluble carbon quantum dots(CQDs) were prepared and used as lubricant additives in deionized(DI) water. The impacts of CQDs on the tribological properties of water were evaluated for both Si_3N_4-on-steel and Si_3N_4-on-Si_3N_4 contacts. Experimental results show that the coefficient of friction(COF) reduced in the two types of tribopairs after the addition of CQDs.Maximum reductions in COF were found to be 30% and 14% for the Si_3N_4-steel and Si_3N_4-Si_3N_4 contacts, respectively. In terms of wear behaviors, the CQDs notably improved tribofilm formation on the Si_3N_4 disk surface for the Si_3N_4-Si_3N_4 contacts,confirming that the nanoparticles increase friction while providing better protection from wear. This research will help to expand the application of CQDs as promising additives in water-based lubricants.     

IC制造中氮化硅薄膜的制备方法

氮化硅薄膜是芯片制造中广泛运用的一种绝缘薄膜,其可用作芯片表面的掩蔽膜及钝化膜。简要介绍IC制造中几种主要的氮化硅薄膜的制备技术,并探讨新型的制备技术。     

YBa＿2Cu＿3O＿（7－δ）高温超导薄膜的保护层研究

论述了钇钡铜氧高温超导薄膜在大气中的不稳定性，对比二氧化硅，阐明了氮化硅薄膜作为保护层的优点，并报导了做潮湿实验前后的对比实验结果．最后讨论了氮化硅作为高温超导薄膜保护层的可行性．     

无压烧结Si_3N_4－MgAl_2O_4－Al_2O_3系复合材料

本文对ｓｉ＿３Ｎ＿４－ＭｇＡｌ＿２Ｏ＿４－Ａｌ＿２Ｏ＿３系复合材料的无压烧结进行了研究。讨论了Ａ１＿２Ｏ＿３含量对材料性能的影响及烧结工艺对材料性能和显微结构的相互关系。实验表明：两段法烧结可以得到性能良好的Ｓｉ＿３Ｎ＿４－ＭｇＡｌ＿２Ｏ＿４－Ａｌ＿２Ｏ＿３复合材料     

自蔓延高温合成法制备MgSiN2粉体

以自蔓延高温合成法制备了高纯MgSiN2粉体。通过绝热燃烧温度的理论计算,提出3种可能的反应体系——Mg粉／Si粉、Mg2Si粉或者Mg粉／Si3N4粉。对3种体系的研究结果表明：Mg粉／Si粉体系很难得到纯相的MgSiN2粉体,Mg2Si粉或者Mg粉／Si3N4粉燃烧可得纯MgSiN2粉体,其氧含量最低可达到0．377％,并具有良好的抗水化性能。     

Facile Fabrication of Fe_2O_3/Nitrogen Deficient g-C_3N_(4-x) Composite Catalysts with Enhanced Photocatalytic Performances

The modification of graphitic carbon nitride can significantly improve the photocatalytic performance of graphitic carbon nitride(g-C_3N_4). Fe_2O_3/nitrogen-deficient g-C_3N_(4-x) composite catalysts were prepared with dicyandiamide as the precursor and Fe~(3+) doped in this study. The composite catalysts were characterized by XRD, SEM, FT-IR, XPS and photocurrent measurements. Close interaction occurred between Fe_2O_3 and nitrogen deficient g-C_3N_(4-x), more photogenerated electrons were created and effectively separated from the holes, resulting in a decrease of photocarrier recombination, and thus enhancing the photocurrent. Photocatalytic performance experiments showed that Fe_2O_3/nitrogen deficient g-C_3N_(4-x) could utilize lowenergy visible light more efficiently than pure g-C_3N_4, and the removal rate was 92% in 60 minutes.