铝合金等离子体基离子注入形成AlN／TiN层结构研究

用X射线光电子能谱和小掠射角X射线衍射研究了铝合金LY12等离子体基离子注入形成的AlN/TiN改性层的结构。结果表明,N和Ti能注入铝合金表面,N在注入层呈类高斯分布,而Ti沿注入方向呈梯度递减。后注入的Ti和N对先注入的N的含量和分布有重要影响。同时注入Ti和N,能在试样表面形成一层稳定的Ti,N层。所形成的AlN/TiN改性层主要由TiO2,TiN,TiAl3,Al2O3,AlN相组成。     

铝合金等离子体基离子注入形成AlN/TiN层结构研究

用X射线光电子能谱和小掠射角X射线衍射研究了铝合金LY12等离子体基离子注入形成的AlN/TiN改性层的结构。结果表明 ,N和Ti能注入铝合金表面 ,N在注入层呈类高斯分布 ,而Ti沿注入方向呈梯度递减。后注入的Ti和N对先注入的N的含量和分布有重要影响。同时注入Ti和N ,能在试样表面形成一层稳定的Ti,N层。所形成的AlN/TiN改性层主要由TiO2 ,TiN ,TiAl3 ,Al2 O3 ,AlN相组成     

铝合金等离子体基离子注入形成AlN/TiN层及其耐磨性能

用X射线光电子能谱 (XPS)和小掠射角X射线衍射 (GAXRD)研究了铝合金LY12等离子体基离子注入形成AlN/TiN改性层的成分分布及相结构 .在此基础上测量了改性层的纳米硬度 ,并进行了摩擦磨损试验 .结果表明 ,氮和钛都能有效地注入到铝合金里 ,后注入的元素对先注元素的含量和分布有重要影响 .钛、氮同时注入在试样表面形成一层稳定的钛、氮化合层 .和未改性试样相比 ,所形成的AlN/TiN改性层纳米硬度及承载能力都提高 5倍以上 .在低滑动载荷下 ,摩擦系数减小 70 %以上 ,耐磨性提高近 10倍 ,耐磨寿命提高了近 6倍 ,粘着磨损程度显著减轻 .随着载荷的增加 ,相应的耐磨性能有所降低 .适当的改性层结构及其中分布的TiO2 、TiN、TiAl3、Al2 O3、AlN等相是性能改善的主要原因     

铝合金等离子体基离子注入形成A1N/TiN层结构研究

用X射线光电子能谱和小掠射角X射线衍射研究了铝合金LY12等离子体基离子注入形成的AIN/TiN改性层的结构.结果表明,N和Ti能注入铝合金表面,N在注入层呈类高斯分布,而Ti沿注入方向呈梯度递减.后注入的Ti和N对先注入的N的含量和分布有重要影响.同时注入Ti和N,能在试样表面形成一层稳定的Ti,N层.所形成的AlN/TiN改性层主要由TiO2,TiN,TiAl3,Al2O3,AlN相组成.     

烧结方法对LiTaO3/Al2 O3复相陶瓷微观组织及力学性能的影响

为了研究铁电／压电陶瓷颗粒对结构陶瓷力学行为的影响规律及机理,分别采用真空热压烧结法和冷等静压成型无压烧结法制备了稳定共存的LiTaO3/Al2O3(LTA)复相陶瓷,对比研究了其微观组织与力学性能,结果表明,1500℃真空热压烧结制备的LTA复相陶瓷中,LiTaO3相熔化,冷却时分布在Al2O3基体晶界,基体晶粒粗化,力学性能较低,200MPa冷等静压成型,1300℃无压烧结制备的LTA复相陶瓷中,LiTaO3颗粒弥散分布,基体晶粒细小,ψ（LiTaO3)为5％的LTA复相陶瓷的力学性能显著改善,强韧化机理为细晶与压电效应和／或电畴运动耗散能量强韧化。     

铝合金等离子体基离子注入形成A1N／TiN层及其耐磨性能

用X射线光电子能谱（XPS）和小掠射角X射线衍射（GAXRD）研究了铝合金LY12等离子基离子注入形成A1N/TiN改性层的成分分布及相结构，在此基础上测量了改性层的纳米硬度，并进行了摩擦磨损试验，结果表明，氮和钛都有效地注入到铝合金里，后注入的元素对先注元素的分布和重要影响，钛，氮同时注入在试样表面形成一层稳定的钛，氧化合层，和未改性试样相经,形成的A1N/TiN改性层纳米硬度及承载能力都提高5倍以上，在低滑动载荷的增加，相应的耐磨性能有所降低，适当的改性层结构及其中分布的TiO2,TiN,TiAl3,Al2O3,AIN等相是性能改善的主要原因。     

原位反应合成TiN/Al2O3梯度复合材料的研究

以Al和TiO2为原料,在匣钵埋碳保护气氛下铝热还原氮化法原位合成制备了TiN/Al2O3梯度复合材料.采用XRD,SEM,EDS和TEM等分析手段,结合热力学计算研究了该梯度复合材料的原位反应过程和材料的物相组成和微观结构.研究结果表明,XRD检测结果与热力学分析结果相吻合,采用埋炭工艺条件下的原位铝热反应可以制得TiN-Al2O3梯度复合材料.TiN/Al2O3梯度试样中各层间没有明显的界面,TiN/Al2O3比沿厚度方向由边缘向中心连续转变,材料的显微结构沿厚度方向由边缘向中心也是梯度变化的,TiN晶粒逐渐长大.     

Li2O对SPS烧结AlN陶瓷致密化、显微结构和导热性的影响

研究了低温烧结助剂Li2O对SPS烧结AlN陶瓷烧结致密化过程、烧结体显微结构和导热性的影响.研究表明:在SPS烧结过程中,烧结助剂Li2O和Sm2O3(或Y2O3)的加入使AlN试样开始收缩并进入烧结初期阶段的温度从1550℃左右下降到1200℃以下;同时Li2O使AlN试样的烧结温度显著降低,完全致密化温度降低到1650℃左右.烧结体的显微结构表明:Li2O的加入有助于形成润湿性良好的液相,促进AlN陶瓷的液相烧结;但不利于快速烧结坯体中气体的扩散与逸出,使试样的致密度受到影响.同时,Li2O影响AlN晶粒的发育,使液相润湿性提高,晶界相均匀分布,增加了晶粒界面上的声子散射,对AlN材料的热导率产生不利影响.同时,添加1.0wt%Li2O和1.5wt%Sm2O3的AlN试样的热导率低于仅添加1.5wt%Sm2O3的试样.     

复合助剂CaF2-Y2O3对AlN-BN复合陶瓷显微结构和热导性能的影响

用热压法制备了AlN-BN复合陶瓷材料,添加CaF2和Y2Os为烧结助剂,研究了烧结助剂的种类、含量以及不同保温时间对复合材料的物相组成、显微结构和热导率的影响.添加复合助剂(1～3)wt%Y2O3-3wt?F2的试样在保温过程中晶界相挥发明显,净化了复合材料的晶界,减少了复合材料中AlN晶格缺陷,获得了纯净的AlN-BN复合陶瓷.与单独添加CaF2助剂的试样相比,添加复合助剂的试样的介电性能没有明显下降,随复合助剂(1～3)wt%Y2O3-3wt?F2中Y2O3含量的增加,AlN-BN复合陶瓷的热导率显著提高.添加复合助剂3wt%Y2Os-3wt?F2的试样在1850℃下保温3h获得的热导率为132.7W·m-1·K-1.     

NiFe2O4/Ag复合材料的制备及其耐蚀和导电性能

以Fe2O3、NiO和Ag2O为主要原料,采用固相烧结工艺制备了NiFe2O4/Ag复合材料,用X射线衍射和扫描电子显微镜对材料的组成和微观结构进行了研究,并测量了样品在冰晶石熔盐中的静态热腐蚀速率及其高温电导率.结果表明,复合材料由NiO、NiFe2O4尖晶石和Ag三相组成.随着Ag2O含量的增多,复合材料的致密化程度先增加而后降低,当Ag2O含量为6%时,试样的致密化程度最高.Ag2O的加入在不提高试样在冰晶石熔盐中的静态热腐蚀速率的前提下,提高了试样的高温电导率.     

晶界相和晶界对AlN陶瓷热导率的影响

本文研究了掺杂CaO Y2 O3热压烧结和常压烧结AlN陶瓷的晶界相及其产生过程和除氧机制 ;分析了两种烧结工艺烧制的AlN陶瓷的晶界成份 ;测定了不同晶界相含量和晶界成份对应的AlN陶瓷的热导率     

反应烧结法制备(AlN,TiN)-Al2O3复合材料的研究

以Ti,Al,Al₂O₃为初始粉料,通过750~800℃氮气保护下的中温焙烧,然后在1420~1550℃在氮气氛下反应烧结,制备了不同配比的(AlN,TiN)-Al₂O₃复合材料。研究了组成及烧结工艺对复合材料力学性能、显微结构等的影响。用XRD,SEM等方法分析粉体及烧结体的相组成及微观结构。分析结果表明:AlN,TiN的形成,有助于材料的致密化并使其力学性能提高。组成为20wt%(Al,Ti)-Al₂O₃的粉体在1520℃、30MPa、保温、保压30min热压烧结条件下,与N₂气反应可得到硬度(HRA)为 94.1的高硬度的(AlN,TiN)-Al₂O₃复合材料,该材料的抗弯强度为687 MPa,断裂韧性(K_IC)为6.5MPa·m1/2。     

Finite Element Analysis of the Microstructure of AlN–TiN Composites

Finite element modelling (FEM) is performed on AlN–TiN composites. The structure–property relationships are studied for 5 and 10 vol.% TiN composites in view of thermal and thermo‐mechanical properties. Thermal stresses are simulated at various temperatures for the 5 and 10% TiN samples in homogeneous and heterogeneous temperature environments. It is found that compressive stresses are associated with the microstructure and these stresses are largest at the interface of the AlN–TiN phases. In addition, thermal strains are simulated at various temperatures for both the compositions. Thermal conductivity and thermal expansion coefficient are estimated using FEM and compared with other known analytical methods.     

AlN-堇青石玻璃复合材料的介电性能

为了研究热压温度和AlN含量对AlN-堇青石玻璃复合材料烧结和介电性能的影响,采用真空热压方法在900~1000℃低温烧结制备AlN-堇青石玻璃复合材料.利用X射线衍射、扫描电镜和阻抗分析仪对复合材料的微结构和介电性能进行了研究.结果表明,随着热压温度的提高,复合材料的相对密度增加,复合材料的介电常数和介电损耗减少;在一定的热压温度下,复合材料的介电常数和介电损耗随着AlN引入量的增加而增加.从复合材料的相组成和结构角度对以上结果予以解释,提高热压温度和增加α-堇青石数量均有利于降低复合材料的介电常数和介电损耗.制备的复合材料具有低的介电常数(5.6~6.5)和低的介电损耗(≤10-3),有望用于微电子封装领域.     

SiO2-AlN复合材料的力学性能和显微结构

热压制备了SiO₂-AlN复合材料。第二相AlN的引入有助于SiO₂基复合材料力学性能的提高。1400℃下热压烧结的30 vol%AlN-SiO₂复合材料的抗弯强度和断裂韧性分别达200 MPa和2.96 MPa·m1/2。XRD分析说明直至1400℃ SiO₂与AlN未发生化学反应,化学相容性好。利用SEM和TEM分析了SiO₂-AlN复合材料的显微结构及其补强机制。      

Chemical vapor deposition of titanium nitride on carbon fibres as a protective layer in metal matrix composites

The significance of carbon fibres for reinforcing metals has increased in the last years, because of their excellent mechanical properties. However, to avoid the weakening reaction during MMC fabrication between the fibre and the liquid metal, a protective coating has to be applied. Continuous carbon fibre roving with 6000 filaments were coated with TiN by thermal induced chemical vapour deposition (CVD) using a gas mixture of TiCl₄, N₂ and H₂ as a precursor. The deposition process in the reactor was simulated by a modified Phoenics-CVD software program using a 2D-axisymmetric model. Carbon fibres reinforced magnesium matrix composites are fabricated by a pressure infiltration casting process. The mechanical properties of the MMCs can be used to demonstrate the efficacy of the coated fibre approach. The rule of mixture is realized to 98% for the coated fibre, and only 48% for the uncoated system. The infiltration pressure during the processing of composites was lowered from 10 to 1 MPa for the TiN coated system.     

The effect of silicon on the wettability and interfacial reaction in AlN/Cu alloy systems

Wetting behavior of AlN by Cu alloys has been studied in vacuum through sessile drop technique. The contact angle was determined by high temperature photography and shape analysis software. Pure copper does not wet AlN. The contact angle of the AlN/Cu system at 1200 °C is 138°. Adding 20 at% Si leads to the decrease of the contact angle from 138° to 96°, and a reaction layer forms in the interfacial area. The addition of Si can also improve the wettability of AlN/Cu10Ti (the atomic ratio of Cu:Ti is 90:10) system. The contact angle of the system decreases to the values less than 20° at 1200 °C by adding 20 at% or 27 at% Si. During the wetting experiment, Ti diffuses to and reacts with AlN, leading to the formation of TiN. Addition of Si can retard the reaction between Ti and AlN by forming a Si-rich layer, mainly composed of Ti-Si compound, between the reaction layer, mainly composed of TiN, and the CuSiTi alloy. The Si-rich layer also contributes to the improvement of the wettability of the system. In the meantime, the addition of Si contributes to the decrease of the stress in the interfacial area and to the bonding at the interfaces.     

AlN-CNTs/聚酰亚胺复合材料的制备与性能

为了研究氮化铝(AlN)和碳纳米管(CNTs)对聚酰亚胺(PI)的导热、热学、力学性能的协同效应,采用湿法球磨和热压成型法制备了AlN/PI和CNTs-AlN/PI复合材料。利用X射线衍射仪、扫描电子显微镜对复合材料进行了物相分析和断面形貌表征,分别考察了AlN及其与CNTs协同对PI复合材料的导热、热学、力学性能的影响。结果表明,AlN和CNTs在PI基体中分散均匀且接触界面良好,AlN的加入可以显著地提高复合材料的导热性能,且对复合材料的热稳定性和力学性能有一定的提高;固定AlN的含量为10%,加入少量的CNTs可以提高复合材料的导热性能,但对复合材料的力学性能有一定的负面影响。     

Growth mechanism of TiN reaction layers produced on AlN via active metal bonding

Interfacial reactions related to the TiN layer growth process between nanocrystalline epitaxial layers of AlN deposited on c-plane sapphire and a Ti-containing metal brazing or sintering layer using Ag–Cu–TiH₂, Ag–TiH₂ and Cu–TiH₂ pastes have been investigated. The brazed/sintered samples were heated in vacuum at 850 °C for 30 min. The TiN layer produced at the metal/AlN interfaces consists of TiN particles?<?50 nm in size and grain boundary phases including Al-containing Ag and Al-containing Cu. The Al concentration within the TiN layer decreases as the distance increases from the AlN epitaxial layer. These experimental observations all suggest that when AlN is used as a starting material in the active metal bonding method, interfacial reaction processes take place with the generation of a local Al-based eutectic liquid phase and elemental transport through this eutectic liquid phase.

     

Review: mechanical behavior of metal/ceramic interfaces in nanolayered composites—experiments and modeling

Recent experimental and modeling studies in nanolayered metal/ceramic composites are reviewed, with focus on the mechanical behaviors of metal/nitrides interfaces. The experimental and modeling studies of the slip systems in bulk TiN are reviewed first. Then, the experimental studies of interfaces, including co-deformation mechanism by micropillar compression tests, in situ TEM straining tests for the dynamic process of the co-deformation, thickness-dependent fracture behavior, and interrelationship among the interfacial bonding, microstructure, and mechanical response, are reviewed for the specific material systems of Al/TiN and Cu/TiN multilayers at nanoscale. The modeling studies reviewed cover first-principles density functional theory-based modeling, atomistic molecular dynamics simulations, and mesoscale modeling of nanolayered composites using discrete dislocation dynamics. The phase transformation between zinc-blende and wurtzite AlN phases in Al/AlN multilayers at nanoscale is also reviewed. Finally, a summary and perspective of possible research directions and challenges are given.