在氧气中焙烧C/γ-Al2O3复合物快速制备α-Al2O3微粉

提出了一种快速制备α-Al₂O₃微粉的方法, 以淀粉为碳源、γ-Al2O₃为前体制备了C/γ-Al₂O₃复合物, 然后在800℃、氧气氛中焙烧制备α-Al₂O₃微粉. N₂物理吸附及SEM分析结果表明, 所制得的α-氧化铝颗粒细小, 约为2μm. 该方法具有焙烧温度低、焙烧时间短的优点, 同时, 淀粉及γ-Al₂O₃均为廉价的工业原料, 且该方法所需淀粉量较少, 最少仅需0.3g/g γ-Al₂O₃, 对应的C/γ-Al₂O₃复合物碳含量约为6wt%, 因而极具工业化应用前景.     

晶种对氢氧化铝转相和热压烧结氧化铝晶形变化的影响

以氢氧化铝为初始原料,通过球磨过程中高纯氧化铝磨介的磨屑作为晶种引入氢氧化铝中.引入的α-Al₂O₃品种使氢氧化铝于1100℃×2h的条件下转变为α相氧化铝.而且随着α-Al₂O₃品种引入量的增加,煅烧后氧化铝颗粒的平均粒径减小,颗粒尺寸分布均匀.煅烧得到的氧化铝超细粉经热压烧结后,Al₂O₃晶粒形貌随品种的引入量的不同而发生变化.未引入α-Al₂O₃品种的条件下,晶粒形状主要为等轴状;晶种引入后,晶粒发育成六角片状;而且随着晶种引入量进一步增加时,六角片状晶粒尺寸减小,当晶种数量增加到20wt％以上时,晶粒发育生长为长柱状.     

常压烧结制备亚微米晶Al2O3陶瓷及其力学性能研究

以高纯α-Al2O3粉体为原料,MgO-Y2O3为烧结助剂,采用常压烧结法制备亚微米晶Al2O3陶瓷。研究了烧结温度、烧结助剂对Al2O3陶瓷的致密化过程、显微结构及力学性能的影响。结果表明:添加一定量的复合助剂MgO-Y2O3可起到促进Al2O3陶瓷致密化,细化显微结构,并改善其力学性能的作用。经1450℃常压烧结1h可获得相对密度达99.6%、平均晶粒尺寸约0.71μm的亚微米晶Al2O3陶瓷,其维氏硬度和断裂韧性分别为18.5GPa和4.6 MPa·m1/2。     

常压烧结制备亚微米晶Al2O3陶瓷及其力学性能研究

以高纯α-Al2O3粉体为原料,MgO-Y2O3为烧结助剂,采用常压烧结法制备亚微米晶Al2O3陶瓷。研究了烧结温度、烧结助剂对Al2O3陶瓷的致密化过程、显微结构及力学性能的影响。结果表明:添加一定量的复合助剂MgO-Y2O3可起到促进Al2O3陶瓷致密化,细化显微结构,并改善其力学性能的作用。经1450℃常压烧结1h可获得相对密度达99.6%、平均晶粒尺寸约0.71μm的亚微米晶Al2O3陶瓷,其维氏硬度和断裂韧性分别为18.5GPa和4.6 MPa·m1/2。     

二步煅烧法制备超细α-Al2O3粉

经由二步煅烧法制备了超细α- Ａｌ_２ Ｏ_３ 粉 Ｘ Ｒ Ｄ 分析说明所制备的粉是α相, Ｔ Ｅ Ｍ 观察到其一次粒子尺寸在８０ ～１００ｎｍ 间, 形貌较规则     

添加Y2O3-Dy2O3的AlN陶瓷的烧结特性及显微结构

本文探索了以自蔓延高温（SHS）法合成并经抗水化处理的AlN粉为原料,以Y₂O₃－Dy₂O₃作为助烧结剂的AlN陶瓷的烧结特性及显微结构．结果表明,晶界处存在Dy₄Al₂O₉、Y₄Al₂O₉、DyAlO₃、Dy₂O₃和DyN等第二相物质,随烧结温度变化,第二相的种类、数量和分布不同,显微结构也随之变化,从而影响AlN的热导率．在1850℃下,可获得热导率为148W／m·K的AlN陶瓷．     

高能球磨结合SPS技术制备Al2O3-TiC复合材料及其性能研究

以TiO₂、Al、C(石墨)为原料,首先采用高能球磨引导铝热反应合成了Al_2O3-TiC 纳米复合粉体,然后采用放电等离子体烧结纳米复合粉体制备了Al₂O₃-TiC复合材料.结果表明,在氩气氛围下高能球磨3h后,原料粉末就发生了铝热反应,合成的Al₂O₃-TiC复合粉体粒子尺寸大约在100nm左右.采用SPS技术在1450℃保温4min烧结的试样致密度达99.6%,并且结构精细(大部分晶粒<1μm),两相分布比较均匀,有较好的力学性能和电导性能,抗弯强度为650±21MPa.,硬度为19.1±0.2GPa,断裂韧性为4.5±0.2MPa·m^1/2,电导率为2.3828×105Ω^-1·m^-1.     

以铝为助剂结合放电等离子烧结制备Ti3SiC2

以铝为助剂结合放电等离子烧结工艺,在较低温度下快速制备出高纯致密Ti₃SiC₂块体材料,掺加适量铝能加快Ti₃SiC₂的反应合成,提高制备材料的纯度,并促进Ti₃SiC₂晶体的生长和材料的快速烧结致密,在升温速率为80℃/min,z轴压力为30MPa时,材料制备的最佳温度为1200～1250℃,所制备材料经XRD、SEM和EDS分析表明不含TiC和SiC等杂质相,Ti₃SiC₂为5～25μm的板状结晶。     

γ-Al2O3纳米粉对氧化铝纤维烧结行为的影响

研究了纳米γ－Ａｌ_２Ｏ_３粉末对氧化铝纤维烧结行为的影响．在纤维挤压成型过程中,纳米粉体填入到微米颗粒形成的孔隙中,当加入量为 ４０ｗｔ％时,纤维素坯相对密度由 ６５％提高到８０％。由于成型密度高、气孔分布窄、孔径小而有利于烧结,在较低的烧结温度下可以达到理论密度．全部采用纳米γ－Ａｌ_２Ｏ_３粉挤压的纤维烧结后具有较大的径向收缩率,在１２００℃烧结即可达到完全致密．     

热等静压制备亚微米细晶氧化铝陶瓷的研究

采用商业氧化铝粉体为原料,MgO为烧结助剂,采用干压结合冷等静压成型素坯,再经适当温度预烧得到具有一定密度的预烧体,对预烧体的晶粒生长与致密化过程进行了研究.素坯在1275℃/160MPa下热等静压烧结2h后得到了平均晶粒尺寸为650～850nm的氧化铝陶瓷.通过万能材料试验机、显微硬度仪测试抛光样品力学性能,得到其三点抗弯强度为(620±30) MPa,硬度HV10为(19.7±0.4)GPa,断裂韧性约2.52MPa·m1/2.     

放电等离子烧结技术制备透明氧化铝陶瓷

采用放电等离子烧结技术(SPS)制备了透明氧化铝陶瓷,研究了样品在模具内部的位置对其光学性能的影响,结果表明,在模具中心处样品的直线透过率最高(波长为640nm时为51%,波长为2000nm时为84%),这主要是由于模具内部温度分布不均引起样品晶粒尺寸不同所致.     

Fabrication of Iron-base Alloy by Spark Plasma Sintering

Fe-2Cu-2Ni-lMo-0.8C (wt pct) elemental mixed powders were rapidly sintered within 6 min by spark plasma sintering, and the effects of sintering parameters on the densification degree and performance of the assintered materials were investigated. Results showed that when a proper combination of pulse electric current and constant electric current was employed for sintering, the density and bend strength of the as-sintered material reached the maxima, being 7.61×103 kg/m3 and 1540 MPa, respectively. Its corresponding fracture morphology was characterized as the mix of ductile, intergranular and cleavage fractures.     

Fabrication of Intermetallic Compounds by Spark Plasma Sintering

The characteristics of spark plasma sintering, a new method of powder processing, were investigated. Four systems of intermetallic compounds—Ti-Al, Ti-Al-Cr, Mo-Si, and Mo-Si-Nb—were fabricated, and the formation process of compounds, the formed phases, and the microstructure of samples were observed. During the sintering of all the compositions of mixed powders, most of the compounds were formed by combustion reaction which occurred at almost the same temperature as the conventional combustion reaction temperature. The fabricated samples were well densified, however, the relative densities of the Mo-Si samples were lower than the Ti-Al samples. Ultrasonic images show that no internal defects were found in any sample and the grain size became finer with the increase in the Cr content in the Ti-Al system and Nb content in the Mo-Si system. The formed phases of Ti:Al=1:1 composition samples were TiAl and Ti₃Al phases, and Ti-Al added Cr samples consisted of TiAl, Ti₃Al, Cr₂Al, and Cr₉Al₁₇ phases. The sample synthesized with Mo:Si=1:2 mixed powders had only MoSi₂ phases, and Mo-Si samples with added Nb consisted of four phases: MoSi₂ with a small amount of Mo₅Si₃ phases in the matrix and Nb₅Si₃ with unreacted Nb for dispersed phases.     

Alumina/tungsten nanocomposites obtained by Spark Plasma Sintering

In the present work, the parameters controlling the alumina/W nanopowders Spark Plasma Sintering (SPS) process are studied. The important and crucial role of C diffusion from the SPS die in the microstructure, fraction of porosity and new phases formation (W₂C) is discussed. It is also pointed out the importance of the processing parameters of the starting powder on the density and mechanical properties of the final compacts. In this regard, dense alumina/nW compacts containing 4 vol.% W with a hardness value as high as 24.6 ± 0.9 GPa were obtained.     

放电等离子快速烧结纳米3Y-TZP材

本文采用放电等离子烧结技术（ＳＰＳ）快速烧结结纳米３Ｙ－ＴＺＰ材料,利用ＳＰＳ技术快速烧结,可制备出完整、致密的３Ｙ－ＴＺＰ材料,在烧结温度为１３００℃,保温３ｍｉｎ条件下,相对密度达９８．２％,晶粒仅１００￣１３０ｎｍ,研究发现,材料的密度随烧结温度的变化趋势与一般快速烧结有明显区别;材料的晶粒随烧结温度的提高而长大,但长大幅度小于其他一些烧结方法所得的３Ｙ－ＴＺＰ材料,本研究对这些现象进行了理     

Transparent Alumina/Ceria Nanocomposites By Spark Plasma Sintering

The influence of oxides (such as MgO, TiO₂, CaO, etc.) on the transparency of polycrystalline alumina compacts are widely studied in the literature. In this work, a completely different approach is developed, consisting of precipitating 0.5 wt.‐% CeO₂ nanoparticles (< 5 nm) on the surface of the starting alumina nanopowder (d₅₀ approximately 170 nm) using cerium(III) acetate as precursor. It is shown that the ceria nanoparticles strongly enhance the transparency of the spark plasma sintered compacts due to: i) the ceria nanoparticles acting as powder lubricant, increasing by around 15% the initial density of the powder in the SPS die, and, ii) the CeO₂ nanoparticles, having a very low solid solubility in the alumina grains, locating at grain boundaries, hindering alumina grain growth by pinning during SPS sintering at 1 430 °C, 80 MPa for 2 min. This effect is found to be effective only under SPS vacuum conditions. In order to explain the light scattering behavior in the near‐infrared and visible range, a light scattering model under the Rayleigh‐Gans‐Debye approximation for polycrystalline alumina is used. This model offers an additional and simple tool for a completed bulk evaluation of the SPS compacts microstructure.     

放电等离子烧结(SPS)技术

放电等离子烧结（SPS）技术是一种新型的材料制备技术。介绍了SPS技术的发展概况、原理、特点及在材料制备领域的应用。最后，对SPS主发展前景进行了展望。     

放电等离子烧结技术

本文介绍了近几年来在日本迅速发展的放电等离子烧结技术,除概要地介绍了这种烧结新技术的原理和特点外,着重介绍了放电等离子烧结技术在制备梯度功能材料和快速烧结细晶粒陶瓷方面的重要应用,其中后者包括了作者最近在日本大阪府立产业技术研究所取得的部分研究结果．     

放电等离子烧结制备Ti3SiC2材料的研究

本文报道分别以Ti/Si/C,Ti/SiC/C为原料,采用放电等离子烧结工艺制备Ti3SiC2材料的研究结果.以元素单质粉为原料,掺加适量Al作助剂能加速Ti3SiC2的反应合成并提高材料的纯度,在1200～1250℃的温度下能制备出经XRD、SME和EDS表征不含TiC和SiC等杂质相的纯净TiSiC2材料.而以Ti/SiC/C为原料时,有无Al作助剂都难以制备出纯净的Ti3SiC2,其反应合成温度明显高于以元素单质粉为原料的.     

SPS烧结制备TiB2/TiC复合材料

采用金属钛粉和碳化硼为初始粉料,利用SPS放电等离子烧结技术制备了致密的纳米结构TiB2/TiC复合材料.并借助XRD、SEM考察了复合材料的相组成和显微结构,利用压痕法和小样品力学性能测试方法(MSP)测定了室温显微硬度、断裂韧性和MSP强度.研究结果表明:利用一步法直接升温至1550℃并保温6 min制备的复合材料,其晶粒尺寸大于1μm,MSP强度为833 MPa.而采用两步法升温至1550℃,然后迅速降低保温温度至1450℃,并保温6 min条件下使金属钛粉和碳化硼同步完成反应、烧结、致密化,生成晶粒细小的TiB2/TiC复合材料,晶粒尺寸大约为200 nm,并且所制备的复合材料力学性能更好,MSP强度达到1095 MPa.