Si-SiO2 interface passivation by plasma NH3 and atomic H

Plasma ammonia treatment at 400 ℃ leads to de-passivation of a fully hydrogenated Si-SiO2 interface, and to passivation of a fully de-hydrogenated Si-SiO2 interface. Plasma NH3 exposure causes irreversible Si surface damage and degradation of thermal stability. Atomic hydrogen exposure, although it results in similar effects on the Si-SiO2 interface, does not introduce additional defects or a decrease of the Si surface thermal stability. The difference between plasma NH3 exposure and atomic H exposure is speculated to be due to either thenitridation of Si-SiO2 interface or radiation damage resulting from plasma NH3 exposure. EPR measurements indicate changes of the paramagnetic defect properties and an increase in the paramagnetic defect density generated by plasma NH3 exposure.     

Microstructure of Si3N4/Si3N4 joint brazed using Cu-Pd-Ti alloy filler

Microstructure of the Si3 N4/Si3 N4 joint brazed using an active filler of Cu-Pd-Ti alloy was analyzed by means of EPMA and XRD. The results indicate that a perfect Si3 N4/Si3 N4 joint is obtained by using an active filler of Cu76.5Pd8.5Ti15 alloy with brazing temperature, pressure and holding time of 1 373 - 1 473 K, 2× 10-3 MPa and 1.8 ks, respectively. The filler alloy in the joint is a Cu-Pd solution containing reactant of TiN, PdTiSi and Pd2Si.The interface between the filler alloy and Si3 N4 ceramic is composed of TiN reactant.     

Development of Si_3N_4/Al composite by pressureless melt infiltration

1 Introduction Composites of ceramic/metal or metal/ceramic are expected to have properties superior to their constituents alone[1?4]. However, the fundamental difference in atomic bonding between metals and ceramics results in quite different physical a…     

固体润滑剂在Ni-Cr合金／Si3N4摩擦副界面的转移行为与摩擦学研究

考察了Ni-Cr-CaF2，Ni-Cr-PbO合金分别与Si3N4配副下的摩擦学性能，运用扫描电镜分析了固体润滑剂在Ni-Cr合金／Si3N4摩擦副界面的转移行为。结果表明，转移膜中CaF2的存在有利于在Si3N4陶瓷上形成有效的转移膜，但是CaF2未在摩擦界面优先转移，而软金属Pb与Si3N4陶瓷的润湿较差，不能存Si3N4陶瓷上形成软金属Pb的完整转移膜。     

化学镀镍层与Si3N4陶瓷的界面反应

采用真空加热和辉光离子轰击加热两种方式,对化学镀镍Si3N4陶瓷进行扩散热处理,并利用X射线衍射仪分析和讨论了化学镀Ni层与Si3N4的界面反应.分析表明,辉光离子轰击扩散能够显著促进镀Ni层与Si3N4的界面反应,其界面反应产物为Ni2Si、Ni3Si和Ni5Si2.随着扩散热处理温度的提高,反应产物的数量明显增加.处理前后,化学镀镍Si3N4陶瓷与金属钎焊接头剪切强度可由70mPa提高至123mPa.     

INTERFACIAL REACTION BEHAVIOUR AND JOINT STRENGTH OF TiCp/Si3N4 COMPOSITE BONDED WITH Al FOIL

１ＩＮＴＲＯＤＵＣＴＩＯＮＴｉＣｐ／Ｓｉ３Ｎ４ｃｏｍｐｏｓｉｔｅｃｅｒａｍｉｃｓｈａｖｅｅｘｃｅｌｌｅｎｔｐｈｙｓｉｃａｌ,ｃｈｅｍｉｃａｌａｎｄｍｅｃｈａｎｉｃａｌｐｒｏｐｅｒｔｉｅｓ,ａｎｄｔｈｅｙａｒｅａｐｐｌｉｅｄｗｉｄｅｌｙｉｎｓｅｖｅ...     

DIELECTRIC PROPERTIES OF NANO Si/C/N COMPOSITE POWDER AND NANO SiC POWDER AT HIGH FREQUENCIES AND MICROSTRUCTURE CHARACTERIZATION

１．ＩｎｔｒｏｄｕｃｔｉｏｎＮａｎｏｍａｔｅｒｉａｌｓａｒｅｉｎｃｒｅａｓｉｎｇｌｙｒｅｃｅｉｖｉｎｇｒｅｃｏｇｎｉｔｉｏｎａｓｐｒａｃｔｉｃａｌｓｔｒｕｃｔｕｒａｌａｎｄｆｕｎｃｔｉｏｎａｌｍａｔｅｒｉａｌｓｗｉｔｈｇｏｏｄｐｒｏｓｐｅｃｔ,ａｎｄｈａｖｅｂｅｅｎｄｅｖｅｌｏｐｅｄｅｘｔｅｎｓｉｖｅｌｙｉｎｒｅｃｅｎｔｙｅａｒｓ．ＴｈｅｎａｎｏＳｉ／Ｃ／ＮｃｏｍｐｏｓｉｔｅｐｏｗｄｅｒａｎｄｎａｎｏＳｉＣｐｏｗｄｅｒｈａｖｅｒｅｃｅｉｖｅｄａｎｉｎｃｒｅａｓｉｎｇｉｎｔｅｒｅｓｔｓｉｎｃｅｔ…     

Study on interfacial structure and strength of Si3 N4/Ti/Cu/Ti/Si3 N4 PTLP bonding

Partial transient liquid-phase bonding (PTLP bonding) of Si3N4 ceramic with Ti/Cu/Ti multi-interlayer is performed with changing the thickness of Ti foil. The influence of Ti foil thickness on interface structure and joint strength was discussed. The joint interface structures are investigated by scanning electron microscope (SEM) and energy dispersion spectroscopy(EDS). The results show that the maximum joint strength of 210 MPa is obtained at room temperature in the experiments. When joining temperature and time are not changed and the process of isothermal solidification is sufficient,interface structure, reaction layer thickness and isothermal solidification thickness change with the thickness of Ti foil.     

Ti／Cu／Ti部分瞬间液相连接Si3N4的界面反应和连接强度

用Ti/Cu/Ti多层中间导在1273K进行氮化硅陶瓷部分瞬间液相连接,实验考察了保温时间对连接强度的影响,用SEM,EPMA和XRD对连接界面进行微观分析,并用扩散路径理论,研究了界面反应产物的形成过程,结果表明：在连接过程中,Cu与Ti相互扩散,形成Ti活度较高的液相,并与氮化硅发生反应,在界面形成Si3N4/TiN/Ti5Si3 Ti5Si4 TiSi2/TiSi2 Cu3Ti2(Si)/Cu的梯度层,保温时间主要是通过影响接头反应层厚度和残余热应力大小而影响接头的连接强度。     

Densification, microstructure, and fracture behavior of TiC/Si3N4 composites by spark plasma sintering

TiC/Si3N4 composites were prepared using the β-Si3N4 powder synthesized by self-propagating high-temperature synthesis (SHS) and 35 wt.% TiC by spark plasma sintering. Y2O3 and A12O3 were added as sintering additives. The almost full sintered density and the highest fracture toughness (8.48 MPa·m1/2) values of Si3N4-based ceramics could be achieved at 1550℃. No interfacial interactions were noticeable between TiC and Si3N4. The toughening mechanisms in TiC/Si3N4 composites were attributed to crack deflection, microcrack toughening, and crack impedance by the periodic compressive stress in the Si3N4 matrix. However, increasing microcracks easily led to excessive connection of microcracks, which would not be beneficial to the strength.     

TiN/Si3N4纳米多层膜硬度对Si3N4层厚敏感性的研究

通过反应磁控溅射制备了一系列不同Si3N4层厚的TiN/Si3N4纳米多层膜,利用X射线衍射仪、高分辨透射电子显微镜、扫描电子显微镜和微力学探针表征了多层膜的微结构和硬度,研究了其硬度随Si3N4层厚微小改变而显著变化的原因.结果表明,在TiN调制层晶体结构的模板作用下,溅射态以非晶存在的Si3N4层在其厚度小于0.7 nm时被强制晶化为NaCl结构的赝晶体,多层膜形成共格外延生长的{111}择优取向超晶格柱状晶,并相应产生硬度显著升高的超硬效应,最高硬度达到38.5GPa.Si3N4随自身层厚进一步的微小增加便转变为非晶态,多层膜的共格生长结构因而受到破坏,其硬度也随之降低.     

Si3N4／BN层状复合陶瓷的防弹结构设计

提出混杂结构设计的构思，并成功地制备了具有混杂结构的Si3N4／BN层状复合陶瓷，同时研究了材料的抗穿甲燃烧弹冲击的能力。研究发现，具有混杂结构的Si3N4／BN层状复合陶瓷的防护系数为10．50，略低于Si3N4块体陶瓷，但明显高于多层Si3N4／BN层状复合陶瓷，而且具有较高的抵抗整体破坏的能力。研究表明通过适当的防弹结构设计，可以获得抗穿甲燃烧弹冲击能力较高的Si3N4／BN层状复合陶瓷。     

Effect of bonding parameters on microstructure and properties of Si_3N_4/Si_3N_4 joint brazed by Cu-Zn-Ti filler alloy

1INTRODUCTION Si3N4ceramichashighthermalandwearingresistanceandisapromisingmaterialforhightem peratureapplications.However,itisdifficultto manufacturetheSi3N4ceramicworkpieceswithla gerdimensionsandcomplicatedshapesduetoitspoorworkabilityandlowductility.Inrecent20years,manystudieshavebeenfocusedonthetech niquesofceramicjoining,becausethejoiningtech niquescanbeusednotonlyforlow costandhigh reliabilitymanufacturingofceramicpartswith complicatedshapesbutalsoforrepairingofthece ramicpartsinw…     

Ti/Cu/Ti部分瞬间液相连接Si_3N_4的界面反应和连接强度

用Ti/Cu/Ti多层中间层在 12 73K进行氮化硅陶瓷部分瞬间液相连接 ,实验考察了保温时间对连接强度的影响。用SEM ,EPMA和XRD对连接界面进行微观分析 ,并用扩散路径理论 ,研究了界面反应产物的形成过程。结果表明 :在连接过程中 ,Cu与Ti相互扩散 ,形成Ti活度较高的液相 ,并与氮化硅发生反应 ,在界面形成Si3N4 /TiN/Ti5Si3 Ti5Si4 TiSi2 /TiSi2 Cu3Ti2 (Si) /Cu的梯度层。保温时间主要是通过影响接头反应层厚度和残余热应力大小而影响接头的连接强度     

Si_3N_4/CrN nanostructured multilayers grown by RF reactive magnetron sputtering

1　INTRODUCTIONInrecentyears ,ceramicsuperhardnesscomposi tionally modulatedmultilayerfilmshavebeenactivelyinvestigated[18] .Theresearchresultsshowthatmul tilayerscancombinethepropertiesoftheconstituentmaterialsandhavemoreexcellent propertiesthanthoseofthesingle layerfilm .Alargenumberofin ternalinterfaceswhichare paralleltothesubstratesurfacecanretardcrackpropagationandprovidebar rierstodislocationmovement.Multilayerswithopti mizedinterfaceareasseemtobemostpromisingwithrespecttoanoptimum…     

TiAl与Si3N4f/Si3N4复合材料钎焊接头界面结构及性能研究

采用AgCuTi钎料实现了TiAl与Si3N4f/Si3N4复合材料的钎焊,确定了钎焊接头的典型界面组织结构为TiAl/AlCuTi/Ag(s,s)/TiN/Si3N4f/Si3N4。钎焊过程中,液相钎料在Si3N4f/Si3N4复合材料表面发生较好润湿,钎料中活性元素Ti与Si3N4基体及纤维发生反应形成连续的TiN化合物层。过高的钎焊温度或过长的保温时间导致钎缝中脆性的AlCuTi化合物增加,且由于接头应力的作用在钎缝中产生微裂纹甚至开裂,严重地降低了钎焊接头性能。当钎焊温度T=850℃,保温时间为10min时,接头抗剪强度达到最大,为9.4MPa,超过Si3N4f/Si3N4母材层间抗剪强度的60%。断口分析表明:压剪过程中,断裂发生在Si3N4f/Si3N4复合材料一侧。     

Mechanism of toughening and strengthening of Si3N4／SiC／ZrO2 nanocomposites

1　INTRODUCTIONInnumerousceramicmaterials ,Si3N4 ceramiciscalled“omnipotentchampion”.Itisnotonlyagoodconstructionmaterialappliedinhightemperature ,butalsoanewfunctionmaterial[1,2 ] .Withthedevel opmentofnanocomposites ,theapplicationinvestiga tionofnewtypeSi3N4 ceramicconstructionmaterialshasenteredanewage .Ithasvastappliedperspec tive[39] .ButthelowtoughnessistheobstacleoftheapplicationofSi3N4 ceramicmaterials ,sohowtoim provethetoughnessofSi3N4 ceramicmaterialsisanurgentproblem .T…     

Si3N4/AgCu/TiAl钎焊接头界面结构及性能

采用AgCu非活性钎料实现了Si3N4陶瓷与TiAl基合金的钎焊,确定接头的典型界面组织结构为:TiAl/Ti3Al+Ti(s,s)/AlCuTi/Ag(s,s)+AlCu2Ti/Ti5Si3+TiN/Si3N4陶瓷。钎焊过程中,活性元素Ti从TiAl母材溶解到钎料中与Si3N4陶瓷发生反应润湿,实现了TiAl与Si3N4陶瓷的连接。随着钎焊温度的升高及保温时间的延长,靠近Si3N4陶瓷的TiN反应层厚度增加,Ag基固溶体中弥散分布的AlCu2Ti化合物聚集长大成块状,导致接头性能下降。当钎焊温度T=860℃,保温时间为5min时接头抗剪强度达到最大值124.6MPa。基于反应热力学及动力学计算TiN层反应激活能Q约为528.7kJ/mol,860℃时该层的成长系数KP=2.7×10-7m/s1/2。     

Study of Fe/Si multilayers by photoemission spectroscopy

The Fe/Si multilayers structure was grown by direct current magnetron sputtering technique and was studied by means of X-ray photoelectron spectroscopy. The iron silicide formation at the oxidized Fe/Si interface is inhibited at room and elevated temperatures and it occurs at T≥500 °C. The prolonged annealing of the Fe/Si interface to 500 °C leads to the steady growth of the Si³⁺ and Si⁴⁺ oxygen-related components in the sample.     

Si3N4／Cu68Ti20Ni12的界面结构及连接强度

采用Cu68Ti20Ni12钎料进行了Si3N4／Si3N4的活性钎焊连接。结果表明：钎焊温度和时间对连接强度有重要影响；在1373K，10min的连接条件下，Si3N4/Si3N4连接强度达到最大值289MPa。通过对Si3N4／Cu68Ti20Ni12界面区的微观分析：发现Ti，Ni明显向Si3N4方向富集，相对Ni而言，Ti的富集区更靠近Si3N4陶瓷，而Si则向钎料方向扩散，Cu在接头中心富集：界面区存在2层反应层，反应层Ⅰ为TiN层，而反应层Ⅱ则由TiN，Ti5Si4，Ti5Si3，Ni3Si及NiTi化合物组成。