AlN陶瓷烧结技术研究进展

氮化铝(AlN)因其具有高热导率,作为基片材料在电子元器件中得到日益重视.本文主要论述了氮化铝陶瓷制备过程中各种烧结参数,包括烧结助剂、烧结气氛、保温时间、常压烧结、热压烧结、微波烧结和等离子烧结等对氮化铝陶瓷性能的影响.并指出可通过合适的AlN粉体制备技术,结合快速烧结方法可得到具有晶粒细小、结构均匀、高致密度和高导热率的AlN陶瓷.     

A1N陶瓷低温烧结过程中氧化控制与性能研究

采用纳米级的A1N粉并以Y2O3-CaF2作烧结助剂于1600℃下制备A1N陶瓷,对AlN陶瓷物相组成、相对密度、微观结构和热性能进行了表征,针对A1N陶瓷烧结过程中易氧化的问题,分析了氮化铝陶瓷在烧结过程中氧化的机理,提出了防止A1N陶瓷制备过程中氧化的措施。研究表明：将A1N坯体置于含有一定量碳粉的A1N埋粉中于N2气氛下烧结,生成还原性气体CO,有效避免了A1N烧结过程中的氧化问题。其中添加3wt％Y2O3-2wt％CaF2作烧结助剂,1600℃常压条件下制备了高热导率的致密A1N陶瓷。     

氮化铝陶瓷的制备及其在复合材料中的应用研究

氮化铝(AlN)陶瓷是一种性能优良的高技术陶瓷.本文概述了AlN陶瓷粉体的合成、成形、烧结的制备过程及其在复合材料中的应用研究,指出要更多地开展AlN复合材料及其在复合材料中应用的研究工作,以满足科技发展对材料提出的更高要求.     

放电等离子烧结AlN陶瓷

研究了放电等离子烧结氮化铝陶瓷的过程。通过对比掺与不掺烧结助剂的氮化铝陶瓷的两种烧结过程，指出了烧结助剂在放电等离子烧结氮化铝陶瓷过程中的作用。利用放电等离子烧结技术烧结氮化铝，在加Y2O3-Li2O-CaF2作为烧结助剂，1700℃的烧结温度，25MPa的压力下，仅保温5min，得到相对密度为97．3％的AlN陶瓷。SEM表明试样内部晶粒细小，结构均匀。实验表明：放电等离子烧结技术可实现快速烧结。     

氧化铝/氮化铝陶瓷显微组织研究

氮化铝具有良好的热学、电学和机械等性能,是理想的电子封装材料和高性能陶瓷基板材料.本文研究了AlN加入量和烧结温度对Al2O3/AlN复相陶瓷相组成和显微组织的影响.结果表明该陶瓷在1400～ 1550℃烧结时,AlN被部分保留,少量氧原子进入AlN晶格,烧结生成4种铅锌矿结构新相,有利于提高复相陶瓷热导率;氮化铝含量和烧结温度的提高,有利于形成大尺寸晶粒.     

烧结助剂对AlN陶瓷制备及性能的影响

用三组烧结助剂[多壁碳纳米管(multi-wall carbonnanotube,MWNT)、Y2O3-CaF2及MWNT-Y2O3-CaF2]在1600℃低温烧结AlN陶瓷,测试AlN陶瓷烧结密度、热性能和电性能,分析其物相变化和微观结构。结果表明:外添加剂在低温能明显促进AlN陶瓷致密化及晶粒生长发育,并且用合适的埋粉和保护气氛可以防止AlN陶瓷在烧结过程中发生氧化,其中添加质量分数(下同)1%MWNT-3%Y2O3-2%CaF2作烧结助剂,于1600℃保温4h可以制备相对体积密度为97.2%,热导率为138.57W/(m·K),同时具有较低相对相对介电常数的AlN陶瓷,即在低温无压条件下制备性能较高的AlN陶瓷。     

Dy和Er掺杂对AlN陶瓷显微结构及性能的影响

在AlN粉末中添加稀土氧化物Dy2O3和Er2O3,采用高温烧结方法制备氮化铝陶瓷,研究了稀土掺杂对陶瓷烧结性能、显微结构及导热性能的影响。结果表明:纯氮化铝陶瓷相对密度只有90.7%,导热率为45.7W/(m·K),而添加3%的Dy2O3的AlN陶瓷相对密度为99.4%%,导热率为84.1W/(m·K),添加3%的Er2O3可使氮化铝陶瓷相对密度提高到99.1%,导热率达到115.4W/(m·k);添加Er2O3可有利于消除氮化铝陶瓷的晶界相,减少氮化铝晶粒缺陷及提高声子在晶体中的传播路程,并显著提高氮化铝陶瓷的结构致密性和导热性能。     

真空热压烧结纳米氮化铝陶瓷的研究

在1500℃、1600℃和1700℃的烧结温度真空热压烧结出以MoSi2为助剂的纳米AlN陶瓷。XRD、SEM、力学性能检测等测试结果表明：制备出的氮化铝陶瓷晶粒细小（100nm左右）,结构均匀,致密度较高、弹性模量和维氏硬度都明显低于纯AlN陶瓷。     

放电等离子烧结氮化铝透明陶瓷的研究

采用放电等离子烧结(spark plasma sintering，SPS)技术烧结氮化铝，在不加任何添加剂的条件下，1800℃，4～20min烧结制备了透明的氮化铝陶瓷。XRD，SEM，EPMA和TEM等测试结果表明，制备出的氮化铝陶瓷纯度较高、晶粒细小、结构均匀，具有良好的透光性能。充分说明SPS技术可应用于透明陶瓷的制备。与此同时，测试结果显示，AlN陶瓷中还含有少量的缺陷，包括位错、层错、气孔、第二相包裹体，这些缺陷无疑会对陶瓷的透光性能产生一定的影响。     

AIN陶瓷烧结技术研究进展

氮化铝（AIN）因其具有高热导率，作为基片材料在电子元器件中得到日益重视。本文主要论述了氮化铝陶瓷制备过程中各种烧结参数，包括烧结助剂、烧结气氛、保温时间、常压烧结、热压烧结、微波烧结和等离子烧结等对氮化铝陶瓷性能的影响。并指出可通过合适的AIN粉体制备技术，结合快速烧结方法可得到具有晶粒细小、结构均匀、高致密度和高导热率的AIN陶瓷。     

Compositions,mechanical properties and microstructures of cBN-based composites sintered with Al or TiC

Cubic boron nitride (cBN)-based composites were prepared from cBN–Al and cBN–TiC mixtures, respectively, under high pressure and high temperature (HPHT). During sintering, Al reacted with cBN and produced AlN and AlB₂, while TiC did not react with cBN. With increasing Al from 5–20?wt-%, the strength of the cBN-based composites decreased first, then increased. AlN and AlB₂ could strengthen the cBN-based composites to a certain extent. In the preparation from cBN–TiC, 10?wt-% addition of TiC was the optimal formulation to obtain the densest microstructure. Hardness of the two kinds of composites displayed different tendencies. On the other hand, cBN-based composites were treated at 1200°C for 1200?s. It was found that the isothermal oxidation process could be described by parabolic laws with slight oxidation scales formed on samples’ surfaces in different morphologies.     

Effect of sintering additive on crystallographic orientation in AlN prepared by slip casting in a strong magnetic field

The preparation of oriented AlN bulk ceramics with and without additives was achieved by slip casting in a high magnetic field. The a and b axes of the AlN were aligned parallel to the direction of the magnetic field. The degree of crystallographic orientation was controlled by the viscosity of the slurry and the grain growth during sintering attributed to the sintering additives. The mechanical properties of the textured AlN depended on the direction of the crystallographic orientation.     

添加Y2O3的AlN陶瓷材料的烧结过程

本研究以先进的进口热膨胀仪为主要手段，探讨了ＡｌＮ材料的烧结过程。用Ｘ射线衍射仪对ＡｌＮ烧结后试样进行了相分析。用最小二乘法回归分析实验数据，依据现有的烧结理论后表明，添加Ｙ２Ｏ３的ＡｌＮ材料的中后期烧结机理为相界反应速率控制的溶解－淀析过程。     

High-strength Ti2AlN ceramics prepared by pulse electric current sintering based on powders synthesized by molten salt method

Ti₂AlN powders were synthesized through molten salt method and re-calcination process using TiH₂, Al and TiN powders as raw materials at 1100 ℃. The composition of final composite was directly influenced by the initial Al and TiH₂ content in the starting mixture. The purity of the synthesized Ti₂AlN powder could reach 97.1 wt% when the Al molar ratio was 1.05. Then high strength Ti₂AlN ceramics were successfully prepared in different modes, including two forms of pulse electric current sintering (PECS/SPS) and hot-pressing sintering (HP). A record-high flexural strength of 719 MPa was obtained for the PECS/SPS with an electrical insulating die (PECS/SPS II) sintered sample, based on the synthesized powder in which the initial molar ratio of Al was 1.1. The sintering behaviors in various modes were analyzed, confirming the shrinkage of particles starting at lower temperature in PECS/SPS II. The density, microstructure, Vickers hardness and elastic modulus of sintered ceramics were also investigated. Therefore, the present work provided the new methods about powder preparation and ceramic sintering of Ti₂AlN, making it possible to be used as high strength structural ceramics.     

Preparation and Thermal Ablation Behavior of HfB2–SiC-Based Ultra-High-Temperature Ceramics Under Severe Heat Conditions

HfB₂–SiC-based ultra-high-temperature ceramics with aluminum nitride (AlN) as a sintering aid were hot pressed at 1850°C. The sinterability and mechanical properties were investigated and compared with the composite without a sintering aid. It was shown that the addition of AlN greatly improved the powder sinterability and enabled the production of a nearly full-dense composite. The mechanical properties, especially the flexural strength, were enhanced remarkably through the improvement in the sinterability and microstructure. The oxidation resistance of a composite doped with 10 vol% AlN was evaluated by a plasma arc heater and the ablation mechanism was discussed.     

Ion-Exchange Loading of Yttrium Acetate as a Sintering Aid on Aluminum Nitride Powder via Aqueous Processing

A novel fabrication process of AlN ceramics via aqueous colloidal processing and pressureless sintering has been presented. The chemical stability of AlN powder in water was improved by the surface chemical modification with sebacic acid, while maintaining a hydrophilic surface. The treatment of the sebacic acid-modified powder with yttrium acetate tetrahydrate resulted in strong immobilization of Y³⁺ ions, as a sintering aid, at a highly dispersive level on the AlN powder surface through ion exchange with the free carboxyl groups of the sebacic acid molecules attached to the AlN surface. By selecting slip compositions for a well-deflocculated condition and firing conditions to burn out organic components in the slip cast compacts, a thermal conductivity of about 250 W/(m·K) could be attained by the pressureless sintering at 1900°C for 5 h.     

氮化铝瓷烧结方法进展

本文综述了氮化铝瓷烧结的发展过程，评价了各种烧结方法的优缺点及适用范围，介绍了氮化铝瓷的最新烧结技术。     

AlN陶瓷的烧结致密化与导热性能

氮化铝陶瓷具有高热导率、低介电常数、与硅相匹配的热膨胀系数等优良特性,应用领域非常广泛。对A l N粉体的合成、烧结工艺、助烧结剂及其应用等方面进行了介绍,并对A l N未来的发展趋势进行了展望。