烧结温度对CuAlO_2陶瓷电性能的影响

为了提高CuAlO_2陶瓷的电导率,满足其在热电器件使用中的要求,以Cu_2O、Al_2O_3为原料,铝硅酸盐玻璃为添加剂,采用两步固相烧结法制备了CuAlO_2(CAO)陶瓷,研究烧结温度对CAO陶瓷电导率的影响.实验发现:随着烧结温度的上升,CAO陶瓷的密度、晶粒尺寸和电导率逐渐增大.烧结温度为1 175℃时,CAO陶瓷的表观密度和相对密度达到最大值,分别为4. 408 g/cm3和95. 8%.当烧结温度达1 200℃时,CAO陶瓷晶粒生长发育完整,呈现多边形结构,且其电导率达到最大(2. 42 S/m),比1 050℃的样品高了近10倍.阻抗谱分析表明,烧结温度对CAO陶瓷电导率的改善主要来自于晶粒阻抗的贡献.     

Ti-B-C-N粉末烧结的微观组织及其性能

以Ti-B-C-N四元相陶瓷粉末为实验材料,采用真空热压烧结和放电等离子烧结(SPS)工艺对其进行烧结,真空热压烧结和放电等离子烧结温度分别为1900℃和1450℃,烧结压力分别为20 MPa和40 MPa,保温时间分别为1h和3min。使用X射线衍射仪分析试样物相组成,扫描电子显微镜观察试样表面微观形貌和断口形貌,并测试了烧结试样的硬度和抗弯强度。结果表明:真空热压烧结和放电等离子烧结块体的主要生成相为TiB2相和TiCN相,相对密度分别为97.40%和93.06%,热压烧结试样致密度高,颗粒尺寸大,放电等离子烧结试样孔隙较多,晶粒尺寸小;抗弯强度分别为259.98 MPa和335.17 MPa;弹性模量分别为89.11GPa和162.92GPa;洛氏硬度分别为78.8和84.9;放电等离子烧结试样表现出较好的力学性能。     

不同粒径碳化硅粉体的复合烧结与表征

以氮化硅为烧结助剂,聚乙烯吡咯烷酮（PVP）为黏结剂,通过重结晶烧结法制备了纯碳化硅（SiC）陶瓷。采用X射线衍射、扫描电子显微镜和阿基米德定律对产物的结构、形貌和相对密度进行了表征,主要研究了SiC细粉的质量分数对SiC晶粒形貌的影响。结果表明,SiC细粉质量分数的变化对烧结样品的晶粒尺寸与形貌及其相对密度有较大影响。细粉质量分数由0%增加至60%,SiC晶粒的形貌由等轴状晶粒过渡为六方片状晶粒,晶粒尺寸非线性增加,样品的相对密度则呈先增加后降低的趋势,当细粉的质量分数为40%时,SiC陶瓷的相对密度最高。因SiC高温（2 000 ℃以上）蒸发与凝聚的烧结作用,当SiC细粉的质量分数为60%时,重结晶普遍发生,且SiC粗粉晶粒尺寸急剧增大,形成六方片状。     

高能球磨时间对钨铜复合材料性能的影响

将W-15wt%Cu粉在行星式高能球磨机中进行球磨,并将球磨粉末加压烧结成型。研究了不同球磨时间对钨铜复合材料性能的影响。采用XRD、SEM对所制备的球磨粉末及烧结合金分别进行物相分析和组织形貌观察,并测定了烧结合金的相对致密度。结果表明,随着球磨时间的增加,钨铜球磨粉末晶粒尺寸得到细化,且有不饱和固溶体产生;烧结合金晶粒尺寸长大,孔洞减少,相对密度增大接近全致密。     

琼脂糖凝胶注模成型3Y-ZrO_2的制备及表征

经球磨且真空除泡后的3Y-ZrO_2浆料通过添加质量分数为4.5%的琼脂糖溶液,制备出了3Y-ZrO_2生坯.生坯于高温烧结炉中在1 550℃下烧结4 h制得3Y-ZrO_2陶瓷.研究了固相体积分数对3Y-ZrO_2生坯相对密度和抗弯强度的影响,固相体积分数对烧结体的密度、抗弯强度、显微结构和物相结构的影响.结果表明,当固相体积分数从47%升高到56%时,生坯的相对密度从47.8%提高到57.2%,其抗弯强度从0.31 MPa提高到0.76 MPa;3Y-ZrO_2陶瓷的密度从5.32 g/cm~3增加到5.81 g/cm~3,其抗弯强度从312.772 MPa提高到427.3 MPa;3Y-ZrO_2陶瓷以四方相为主,晶粒尺寸均匀,几乎没有气孔.     

烧结温度对Ba(Fe0.5Nb0.5)O3陶瓷微观结构与介电性能的影响

在1 300~1 400℃采用固相法制得了致密的Ba(Fe0.5Nb0.5)O3(BFN)陶瓷,并对其微观结构和介电行为进行研究.XRD分析表明不同烧结温度下都获得了单相立方结构的BFN陶瓷.陶瓷的平均晶粒尺寸和介电常数都会随着烧结温度的升高而增大,且当烧结温度升高到1 400℃时,陶瓷的晶粒尺寸急剧增大,介电常数从18 868急剧增到45 167,介电损耗从0.66降低到0.43.复阻抗分析表明,BFN陶瓷的微观结构是由半导的晶粒和绝缘的晶界构成,可等效为由两个平行RC元件组成的串联电路.根据IBLC巨介电理论模型,介电常数的增加源于平均晶粒尺寸与晶界厚度的比值(tg/tgb)增加,并且晶粒的尺寸增加占主导地位.BFN陶瓷巨介电常数的外部起源与微结构有关.     

低温低压烧结WC-8Co硬质合金

采用低温低压烧结WC-8Co硬质合金,并研究了烧结温度和烧结压力对硬质合金组织和性能的影响.研究结果表明:随着烧结温度的升高,WC-8Co硬质合金的孔隙减少,晶粒尺寸和密度增大;硬质合金的硬度与抗弯强度随着密度的增大而提高.当烧结温度高于1 280℃时,WC-8Co硬质合金的烧结方式为液相烧结;烧结压力有利于硬质合金的致密化.当烧结温度为1 300℃,烧结压力为5 MPa时,WC-8Co硬质合金的密度、硬度和抗弯强度分别为14.61 g/cm3、90.7 HRA和1 830 MPa.     

图像分析技术分析晶粒对Ti_3AlC_2/TiB_2材料性能的影响

采用DS-5M图像分析仪分析了不同TiB2含量的Ti3AlC2/TiB2复合材料微观晶粒大小和分布情况,分析结果表明,TiB2体积含量为10%的烧结样品晶粒发育较完善,分布也较均匀,随着TiB2含量的增加,层状晶粒的生长受到进一步的抑制,晶粒尺寸明显变小。采用阿基米德常数法测定烧结试样的密度,发现TiB2体积含量为10%的烧结样品相对密度最大,达到99.07%,TiB2体积比含量超过10%,相对密度逐渐减小;SPS烧结过程中TiB2体积含量少于10%时,样品呈现一个很窄的快速致密化阶段,随着TiB2含量的增加,原料发生反应所需温度升高和反应过程所需时间增加,降低了材料的致密化程度。可见图像分析复合材料微观晶粒的情况能很好地呼应材料宏观性能测试结果,提供了一种有效的测试分析手段。     

热处理温度对TiO2薄膜性能的影响

采用直流反应磁控溅射法在玻璃基片上制备了TiO薄膜，靶材为纯度99．9％的钛靶，溅时基片不加热。XRD结果显示，所得TiO薄膜的晶型为锐钛矿相；SEM结果显示，随着热处理温度的增加TiO薄膜晶粒尺寸增大，光催化性能显示，经过500℃热处理1h后的TiO薄膜具有较好的光催化效率。     

烧结制度对Ba(Mg1/3Nb2/3)O3陶瓷品质因子的影响

研究了烧结温度、保温时间、退火时间等工艺参数对Ba(Mg1／3Nb2／3)O3微波介质陶瓷品质因子的影响。结果表明，随着烧结温度的提高，Qf值逐渐增加，这是由于陶瓷的相对密度和有序参数S也随烧结温度增加的结果。在1550℃时，Qf达到最大值49500GHz。Qf值随保温时间的增加而增加，这和B位1：2有序度提高和晶粒尺寸增大有关。保温时间为16h时，Qf值达到58000GHz。退火时间对Qf值有很大影响。随退火时间的增加，Qf值增加很快，这主要是因为退火大大促进了B位离子的1：2有序。当退火时间为48h时，Qf值达到71500GHz。     

Microstructure and mechanical properties of 8YSZ ceramics by liquid-phase sintering with CuO-TiO2 addition

The 8% (mass fraction) yttrium-partially-stabilized zirconia (8YSZ) ceramic was fabricated via liquid phase sintering at 1 200–1 400 °C by adding different mass ratios of CuO-16.7%TiO₂ (molar fraction) as sintering aid. Relative density, microstructure, Vickers hardness and bending strength as a function of sintering temperature and additive content were investigated. The experiment results show that liquid phase sintering at low temperature can be realized through adding CuO-16.7% TiO₂ to 8YSZ. The Vickers hardness and bending strength of samples with sintering aid are generally much higher than those of samples without sintering aid for all sintering temperatures, and increase with the increase of sintering temperature. When the addition content of CuO-16.7% TiO₂ is beyond 0.5%, the relative density, Vickers hardness and bending strength decrease with the increase of the mass ratio of sintering aid. Low additions of sintering aid are beneficial to aiding densification; high additions of sintering aid are detrimental to the sintered properties mainly due to greater amounts of pores generated by the volatilization of oxygen with the eutectic reaction between copper oxide and titanium dioxide. It is found that the fine grain size and high relative density are two main reasons of the high bending strength and Vickers hardness of the materials.     

球磨WC-8Co粉末的放电等离子烧结

对WC-8Co粉末不同球磨时间后进行放电等离子烧结,研究了球磨时间及烧结温度对WC-8Co硬质合金微观结构及性能的影响。结果表明:球磨时间延长,粉末颗粒变细,晶格畸变增加,衍射峰强度降低,并随时间延长,团聚现象严重;采用放电等离子烧结,在1 200℃时,可以得到接近全致密的烧结样品,烧结温度低于传统方法的烧结温度;球磨时间在2 h以下时,样品的致密度、硬度和断裂韧性达到最佳,晶粒较小且分布均匀;延长球磨时间,性能显著下降且出现较多粗晶、空洞、Co池等缺陷。     

Sintering Mechanism of Stainless Steel in Powder Injection Molding

Stainless steel samples were made by Powder injection Molding (PIM) process with-400 mesh powder in order to investigate the sintering mechanism in this system and develop the PIM of stainless steels. The process included mixing, injection molding, debin- ding and sintering. Neck growth model was used to analyze the sintering mechanism. The results show that lattice (volume) diffusion is the main mechanism in the sintering process, the products with higher density (>95%) and properties are obtained. At lower temperatures, grain boundary diffusion may play a role in the sintering densification.     

烧结温度对氧化物法制备Ni-Zn铁氧体的介电性能影响

采用氧化物法制备了Ni0.5Zn0.5Fe2 O4铁氧体;样品的相组成成分、微结构和介电性能分别采用X射线衍射仪(XRD)、扫描电镜(SEM)、阻抗分析仪进行表征,讨论了经不同温度预烧和烧结后的样品微结构和介电性能.结果表明:950℃和1 000℃预烧的样品有Fe2 O3第2相产生,随着烧结温度的升高,微晶尺寸和密度逐渐增大;介电常数呈现先减小后增大的趋势,在1 200℃时有最小值;1 300℃下烧结样品的介电损耗角正切有峰值出现,表现出了异常的介电行为.     

Pressureless reactive sintering mechanism of nanocrystalline Bi2O3-Y2O3 solid electrolyte

The nanocrystalline Bi2O3-Y2O3 solid electrolyte material was synthesized by pressureless reactive sintering process with Bi2O3 and Y2O3 nano mixed powder as raw materials, which was prepared by a chemical coprecipitation process. The study on the behavior of nano δ-Bi2O3 formation and its grain growth showed that the solid solution reaction of Y2O3 and β-Bi2O3 to form δ-Bi2O3occurs mainly in the initial stage of sintering process, and nano δ-Bi2O3 crystal grains grow approximately following the rule of paracurve ((D-D0)2=K.t) during sintering process. After sintered at 600℃ for 2 h, the samples could reach above 96% in relative density and have dense microstructure with few remaining pores, the δ-Bi2O3 grains are less than 100 nm in size.     

Sintering of the NiFe2O4-10NiO/xNi Cermet

The sintering behavior of NiFe2 O4-10NiO/xNi cermet which was used as the most prospective inert anode materials for aluminum electrolysis was studied by examining the effects of raw powder particle size, sintering temperature, and the contents of Ni. The results show that fine particle size enables the powder to have high driving force for sintering. High temperature is beneficial to densification, but the ultra-high temperature does harm to the improvement of the density. The samples of NiFe2O4-10NiO/SNi has the highest relative density of 97.28 % when it is sintered at 1 350 ℃, but it decreases to 95.23 % when sintered at 1 400 ℃. Low addition of Ni has a great help to the sintering of NiFe2 O4-10NiO matrix. When the samples are sintered at 1 350 ℃ and the mass fraction of Ni is 5%, the highest relative density is gained, but the density decreases with the further increase of Ni contents. The low density of the sintered samples of NiFe2 O4-10NiO/17Ni is attributed to the high volume fraction of pores.     

Effects of sintering atmosphere on the microstructure and mechanical property of sintered 316L stainless steel

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Relation between powder size and electrolyte properties in nano YSZ system

YSZ (yttria stabilized zirconia) electrolyte properties made from different sizes of nano powders were investigated. As a result, the sample marked KD with the smallest size (10 nm) of first particles and the sample marked TH with narrow distribution and the smallest median diameter Mmcd of 0.49μm have the best sintering properties and the highest electrical conductivity. There is a very well correlation between the density and the electrical conductivity of YSZ, that is, the samples with a higher density have a higher electrical conductivity. The area resistance of YSZ electrolyte made in the experiment, such as TH of 0.483 Ω.cm^2, is much lower than that of the sample D of 1.300 Ω.cm^2 made in Germany at 850℃. The complex resistance of YSZ electrolyte made in the experiment at the grain, grain boundary and electrode in the range of 300-750℃ decreases greatly compared to the sample made in Germany by shown in the complex impedance plot.     

Kinetic characteristics of liquid phase sintering of mechanically activated W-15wt% Cu powder

The kinetic characteristics of W grain growth operated by diffusion controlled Oswald ripening （DOR） during liquid phase sintering were studied. A liquid phase sintering of W-15wt%Cu was carried out by pushing compacts into a furnace at the moment when the temperature increased to 1340℃ for different sintering times. The results show that liquid phase sintering produces the compacts with considerably low relative density and inversely, rather high homogeneity. On the basis of the data extracted from the SEM images, the kinetic equation of W grain growth, G^n = G0^n ＋ kt, is determined in which the grain growth exponent n is 3 and the grain growth rate constant k is 0.15 μm^3/s. The cumulative normalized grain size distributions produced by different sintering times show self-similar. The cumulative distribution function is extracted from the curves by non-linear fitting. In addition, the sintering kinetic characteristics of W-15wt%Cu compacts were also investigated.     

Effects of activated sintering process on properties and microstructure of W-15Cu alloy

The effects of activated sintering technology of H2 atmosphere sintering on the microstructure and properties of W-15Cu alloy using ultrafine W-15Cu composite powder fabricated by spray drying calcining-continuous reduction technology were investigated.The experimental results showed that W-15Cu alloy,consolidated by activated sintering technology of H2 atmosphere sintering for 1 h at 1300 ℃,with 98.5 % relative density,transverse rupture strength 1218 MPa,Vickers hardness HV0.5 378,average grain size about 1.2 μm and thermal conductivity 192 W/m·K,was obtained.In comparison to the normal sintering process,activated sintering process to W-15Cu alloy could be achieved at lower sintering temperature.Furthermore,better properties in activated sintered compacts were obtained,and activated sintering process resulted in finer microstructure and excellent properties.