Y2O3加入量对AIN陶瓷导热率的影响

将不同量Y2O3烧结助剂加入AlN纳米粉体,进行N2气氛常压烧结。实验表明,AlN陶瓷致密度随Y2O3加入量的增大而增大,Y2O3烧结助剂加入量在1～3wt％时,导热率随温度上升而上升,Y2O3烧结助剂加入量超过4wt％时,导热率反而下降。     

Y_2O_3加入量对AlN陶瓷导热率的影响

将不同量Y2O3烧结助剂加入AlN纳米粉体,进行N气氛常压烧结。实验表明,AlN陶瓷致密度随Y2O3加入量的增大而增大,Y2O3烧结助剂加入量在1～3wt%时,导热率随温度上升而上升,Y2O3烧结助剂加入量超过4wt%时,导热率反而下降。     

AlN陶瓷低温烧结制备与性能研究

采用两组复合烧结助剂Y2O3-CaF2,Y2O3-CaF2-Li2CO3在1600℃烧结AlN陶瓷,对AlN陶瓷烧结密度,热性能和电性能进行了测试,并分析了AlN陶瓷物相变化和微观结构。结果表明,复合烧结助剂在低温下能明显促进AlN陶瓷致密化及晶粒生长发育,尤其是添加3wt%Y2O3-2wt%CaF2作烧结助剂,1600℃常压烧结4h制备了结晶良好,相对密度为98.4%,热导率为133.62W/m.K,同时具有较低相对介电常数的AlN陶瓷。在低温常压条件下制备出性能较高的AlN陶瓷。     

Dy2O3–CaF2对AlN陶瓷制备、结构及性能的影响EI北大核心CSCD

以AlN粉体为原料,采用无压烧结,选取二元烧结助剂Dy2O3–CaF2在1 800℃氮气气氛下烧结AlN陶瓷,利用Archimedes排水法、X射线衍射、扫描电子显微镜、激光导热分析仪和万能材料试验机对烧结的AlN陶瓷的密度、热性能和力学性能进行了测试,并对AlN陶瓷的物相变化和微观结构进行了表征。结果表明：添加二元烧结助剂Dy2O3–CaF2可以有效促进AlN陶瓷致密化以及晶粒的生长发育,降低AlN陶瓷的烧结温度,改善AlN陶瓷的导热性能。当添加2.5%（质量分数）Dy2O3＋1.5%（质量分数）CaF2在1 800℃氮气气氛下常压烧结2 h时,制备出了晶粒发育良好、结晶良好,相对密度99.6%,热导率169 W/（m·K）,同时具有较高的机械强度的AlN陶瓷。     

AlN-Pr2O3液相烧结SiC陶瓷

以AlN、Pr2O3做为SiC陶瓷液相烧结的复合助剂,选定不同的助剂含量(5wt％～ 20wt％)和不同的助剂摩尔比例(Pr2O3/AlN=1/3、1/1、3/1),在1800～2000℃温度下,采用热压和无压烧结的方法制备SiC陶瓷样品,并对这些陶瓷样品的性能进行了研究.实验结果表明,助剂比1/3组的样品显示出更有效地促进SiC陶瓷致密化,该组样品无压烧结最大相对密度为87％,热压烧结具有最高的相对密度96.1％、维氏硬度23.4 GPa、抗弯强度549.7MPa、断裂韧性5.36 MPa·m1/2,显微结构中可观察到晶粒拔出现象,断裂模式为沿晶断裂.     

高压烧结AlN（Y2O3）陶瓷的物相组成分析及热导率

用国产六面顶压机在5.0GPa,1300℃～1800℃条件下实现了以Y2O3为烧结助剂的AlN陶瓷体的高压烧结.用XRD对AlN高压烧结体的相组成进行了表征.研究表明:高压制备陶瓷体材料能够有效降低烧结温度和缩短烧结时间,可比传统烧结方法降低400℃以上.Y2O3是AlN有效的低温烧结助剂,在1300℃、1400℃烧结的AlN陶瓷体材料第二相物质以YAlO3和 Y4Al2O9为主.当烧结温度高于1600℃,AlN陶瓷的第二相物质主要以Y3Al5O12为主.烧结条件为5.0GPa/1700℃/75min,样品的热导率可达135W/(m·K).     

烧结助剂添加量对微波烧结3Y-TZP/Al2O3复相陶瓷性能的影响

本文分别以TiO2和MgO纳米粉体为烧结助剂,采用微波烧结技术制备了3Y-TZP/Al2O3复相陶瓷.研究了烧结助剂含量对材料相组成、致密化及力学性能的影响,通过XRD分析了复相陶瓷中t-ZrO2相的相对量变化,并采用SEM观察了弯曲断裂断口形貌.结果表明:随烧结助剂添加量的增加,微波烧结复相陶瓷的致密度、硬度和弯曲强度均有所增加,均优于传统烧结性能,陶瓷颗粒更细.烧结助剂添加量为0.2wt％ MgO、0.4wt％ TiO2,在1300℃微波烧结30 min时试样的致密度为98.1％,显微硬度和抗弯强度分别达18.9 GPa和626 MPa.     

反应烧结制备碳化硅-氮化铝复合材料

采用硅作为熔渗剂,利用真空反应烧结的工艺,在1600℃烧结制得了结构致密、密度低的碳化硅-氮化铝(SiC/AlN)复合材料,分析测试了所制得的复合材料的物相、微观结构和力学性能.结果表明,氮化铝的添加量由2wt％增加到10wt％时,复合材料的力学性能出现先增加后减小的趋势,当AlN含量为6wt％时,得到复合材料的力学性能最高,其抗弯强度为256 MPa,显微硬度为2660 HV.加入AlN后,复合材料的孔隙率略微有点上升,烧结体的密度在2.95 ～3.01 g/cm3之间.复合材料的主要组成相为SiC、AlN和Si.     

两面顶技术低温超高压烧结AlN陶瓷的研究

本文研究了掺杂不同质量分数的Y2 O3的AlN陶瓷在超高压状态下烧结的物相组成和微观结构。研究表明 ,Y2 O3是有效的低温烧结助剂 ,在低温超高压烧结下 ,掺杂不同比例烧结助剂的AlN陶瓷的第二相均为Al5Y3O1 2 ,在实验条件为 4 4万个大气压 ,1 5 0 0℃的温度 ,1h的烧结时间下 ,超高压烧结AlN陶瓷有着较好的微观结构 ,热导率可达到 1 3 0W/m·K。     

AlN改善Al2O3陶瓷导热性能的研究

本文选用导热系数较高的AlN来改善Al2O3陶瓷的导热性能;并借助SEM和XRD对材料的微观结构和物相进行了分析.结果表明：AlN/Al2O3基复合材料的导热性能随AlN含量的增加呈现先增大后减小的有规律变化,并在AlN的外加量达到7%时具有最佳值;另外,探讨了AlN的加入导致主晶相Al2O3的晶胞参数、晶粒大小、烧结气孔率的变化及它们对材料导热性的影响规律.     

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。     

Low-temperature hot-press sintering of AlN ceramics with MgO–CaO–Al2O3–SiO2 glass additives for ceramic heater applications

Aluminum nitride (AlN) is used a ceramic heater material for the semiconductor industry. Because extremely high temperatures are required to achieve dense AlN components, sintering aids such as Y₂O₃ are typically added to reduce the sintering temperature and time. To further reduce the sintering temperature, in this study, a low-melting-temperature glass (MgO–CaO–Al₂O₃–SiO₂; MCAS) was used as a sintering additive for AlN. With MCAS addition, fully dense AlN was obtained by hot-press sintering at 1500 °C for 3 h at 30 MPa. The mechanical properties, thermal conductivity, and volume resistance of the sintered AlN–MCAS sample were evaluated and compared with those of a reference sample (AlN prepared with 5 wt% Y2O3 sintering aid sintered at 1750 °C for 8 h at 10 MPa). The thermal conductivity of AlN prepared with 0.5 wt% MCAS was 91.2 W/m?K, which was 84.8 W/m?K lower than that of the reference sample at 25 °C; however, the difference in thermal conductivity between the samples was only 14.2 W/m?K at the ceramic-heater operating temperature of 500 °C. The flexural strength of AlN–MCAS was 550 MPa, which was higher than that of the reference sample (425 MPa); this was attributed to the smaller grain size achieved by low-temperature sintering. The volume resistance of AlN–MCAS was lower than that of the reference sample in the range of 200–400 °C. However, the resistivity of the proposed AlN–MCAS sample was higher than that of the reference sample (500 °C) owing to grain-boundary scattering of phonons. In summary, the proposed sintering strategy produces AlN materials for heater applications with low production cost, while achieving the properties required by the semiconductor industry.     

臭氧发生器用AlN陶瓷基板材料的研究

为了提高臭氧发生器的臭氧产量,要求臭氧发生器用的陶瓷基板材料具有较高的介电性能和热导率.本文研究了掺杂成分CaO、Y2O3、YF3、(Y,Ca)F3对臭氧发生器用AlN陶瓷基板材料的相对密度、热导率、介电常数、介质损耗等性能的影响.采用XRD分析其物相和SEM观察其显微结构,结果表明,掺杂成分对改善陶瓷基板材料性能的作用大小依次排列为(Y,Ca)F3>YF3>Y2O3>CaO,最适合的掺杂配方是(Y,Ca)F33.0wt%,YF32.0wt%,Y2O31.0wt%,CaO1.0wt%.     

Thermal conductivity of AlN ceramics sintered with CaF2 and YF3

Dense AlN ceramics with a thermal conductivity of 180W/m·K were obtained at the sintering temperature of 1750 °C using CaF₂ and YF₃ as additives. At temperatures below 1650 °C, the shrinkage of AlN ceramics is promoted by liquid (Ca,Y)F₂ and Ca₁₂Al₁₄O₃₂F₂. Liquid CaYAlO₄ mainly improves the densification of the sample when the sintering temperature increases to 1750 °C. The formation of liquid (Ca,Y)F₂ at a relatively low temperature results in homogeneous YF₃ distribution around the AlN particles, which benefits the removal of oxygen impurity in the AlN lattice, and thus a higher thermal conductivity.     

High infrared emissivity of SiC-AlN ceramics at room temperature

SiC-AlN ceramics were fabricated by pressureless sintering with B₄C-C as sintering additives. The effects of AlN contents on infrared emissivity, thermal conductivity and electrical properties of SiC ceramics were investigated. The improvement of total emissivity is slight before 3 wt%AlN, but impressive after 3 wt%AlN. The significant increase of the emissivity for AlN content higher than 3 wt% could be explained via DFT calculation, that the impurity energy level formed by N atom doping into 4H-SiC and the lattice distortion are mainly responsible for it. Besides, the highest total emissivity is 0.775 when the content of AlN is 5 wt%. Additionally, more AlN solid solution results in a decrease in thermal conductivity and an enhancement in electrical resistivity. There is always a compromise among the three properties of SiC-AlN ceramics.     

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。     

AlN with high strength and high thermal conductivity based on an MCAS-Y2O3-YSZ multi-additive system

The additive composition of an AlN ceramic substrate material was optimized to achieve high strength and thermal conductivity. MgO-CaO-Al₂O₃-SiO₂ (MCAS) glass and Y₂O₃ were used as basic additives for improved sintering properties and thermal conductivity, thereby allowing for AlN to be sintered at a relatively low temperature of 1600 °C without pressurization. Yttria-stabilized zirconia (YSZ) was added (0–3 wt%) to further improve the strength of the AlN ceramic. YSZ and Y₂O₃ reacted with AlN to produce ZrN, Y₄Al₂O₉, and Y₃Al₅O₁₂ secondary phases. The formation of these yttrium aluminate phases improved the thermal conductivity by removing oxygen impurities, while ZrN formed at the AlN grain boundaries provided resistance to grain boundary fractures for improved strength. Overall, the AlN ceramic with 1 wt% MCAS, 3 wt% Y₂O₃, and 1 wt% YSZ exhibited excellent thermal and mechanical properties, including a thermal conductivity of 109 W/mK and flexural strength of 608 MPa.     

Effects of doping Al-metal powder on thermal,mechanical and dielectric properties of AlN ceramics

In this work, the influence of Al-metal powder addition upon that thermal, mechanical and dielectric properties of aluminium nitride (AlN) ceramic was studied. The findings show that adding Al-metal powder improves not only the mechanical and thermal properties of the AlN ceramic but also has no negative impact on its dielectric properties. Based on Y₂O₃ as sintering aid, the AlN ceramic with 1.0 wt% Al doping were 14.35% higher thermal conductivity, 11.73% higher flexural strength and 59.50% higher fracture toughness than those doped without Al, respectively. This study showed that the addition of Al-metal powder may favor the purifying of the AlN lattice and the formation of homogenous and isolated second phase, which would increase the AlN–AlN interfaces and improve the thermal conductivity. Furthermore, the grain boundaries of AlN ceramics might be strengthened by the isolated second phases due to the thermal mismatch between the second phases and AlN grains, thus strengthening and toughening the AlN ceramic doped with Al. However, the large additive amount of Al powder (>1.0 wt%) was not help the isolation and homogenization of the second phase, giving a deterioration in an AlN ceramic's mechanical and thermal properties. These results suggest that the introduction of an appropriate dose of aluminium metal powder is a simple method that can be used to improve the AlN ceramic's mechanical and thermal properties simultaneously.     

不同烧结气氛下制备的AlN陶瓷结构和电性能的差异

以AlN粉末为原料、Y2O3粉末为烧结助剂,分别在氮气气氛下和真空气氛下,采用放电等离子烧结方法在1700℃、25MPa条件下保温10min制备AIN陶瓷。X-射线衍射、扫描电镜和X-射线光电子能谱分析表明：不同烧结气氛下制备的AlN陶瓷的结构和体积电阻率各有不同。真空气氛AlN陶瓷与氮气气氛AlN陶瓷相比较,除舍有主晶相AlN和第二相Y3Al5O12外,还含有微量Al2Y相。正是由于微量Al2Y相的存在,使得真空气氛下得到的AlN陶瓷比氮气气氛下得到的A1N陶瓷的体积电阻率低约2个数量级。