Y2O3和La2O3对金属陶瓷内衬显微硬度和耐蚀性的影响

研究了钇、镧等添加物对金属陶瓷内衬显微硬度和耐蚀性的影响.结果表明加入Y2O3、La2O3和SiO2可使陶瓷层的孔隙度降低,一定程度上使耐蚀性增加.La2O3对提高陶瓷层性能的效果比Y2O3要好.     

添加Y2O3的ZrO2增韧Al2O3陶瓷抗钢液腐蚀性能的研究

采用工业ZrO2和AlO3为原料,以Y2O3作为稳定剂,通过适当工艺制备出ZrO2增韧Al2O3(ZTA)陶瓷.主要研究了ZrO2和Y2O3稳定剂对ZTA陶瓷烧结性和抗钢液腐蚀性能的影响.实验结果表明:机械混合法引入的Y2O3在改善ZTA陶瓷的烧结性的同时,可以提高材料的抗钢液腐蚀性能;随ZrO2含量的增加,ZTA陶瓷的抗钢液腐蚀性能增强;材料中大量微裂纹的存在可以提高材料的韧性,但抗钢液腐蚀性能有所下降.     

反向共沉淀法制备Y2O3-ZrO2陶瓷粉末

鉴于在ZrO2中加入Y2O3做稳定剂可有效提高ZrO2陶瓷的高温相稳定性,以ZrOCl2.8H2O和YCl3为原料,聚乙二醇(PEG)为分散剂,采用反向共沉淀法制备出Y2O3-ZrO2陶瓷粉末.利用XRD、SEM、DSC-TG、BET和激光粒度衍射对Y2O3-ZrO2粉末进行性能表征.结果表明:Y2O3-ZrO2粉末在800 ℃煅烧后的平均晶粒尺寸为25.2 nm,采用喷雾干燥得到的粉末球形度好,粒度分布窄;加入适量分散剂能较好地抑制颗粒团聚.     

ZrO2(Y2O3)对燃烧合成A12O3/YSZ自生复合陶瓷显微结构与力学性能的影响

在铝热剂中引入不同量ZrO2(3Y)微米粉末,以燃烧合成技术,制备出A12O3/10%、17%、21%、27%、33%ZrO2(3Y)系列成分自生复合陶瓷棒材.XRD分析与SEM观察显示:具有亚共晶成分的陶瓷熔体因以离异共晶方式生长,使得凝固后的陶瓷基体主要由α-A12O3片晶、t-ZrO2枝晶或块晶组成;而随ZrO2(3Y)添加量的增多,陶瓷晶体生长方式又由离异共晶向共生共晶生长发生转化,共晶棒晶体积分数增多,使得A12O3/33%ZrO2(3Y)的陶瓷基体以微米、亚微米t-ZrO2纤维镶嵌其上的A12O3共晶棒晶和少量α-A12O3片晶构成.经力学性能测试,系列陶瓷棒材的硬度与断裂韧度随ZrO2(3Y)添加量增多而逐渐升高,陶瓷棒材硬度最高值达15.7GPa,断裂韧度最高可达10MPa·m1/2.     

注射成形AIN-Y2O3陶瓷的结构与性能

采用粉末注射成形方法制备了具有高导热性能的AIN陶瓷导热材料,研究了烧结温度对注射成形AIN陶瓷致密化的影响,及不同Y2O3含量对注射成形AIN陶瓷的晶界第二相、热导率和显微结构的影响.结果表明:在本实验条件下,当烧结温度在1850℃时,AIN的相对密度达到99.5%;Y2O3的添加量对AIN的晶界第二相的影响和传统AIN制备工艺中有较大的不同,在Y2O3含量为3%(质量分数,下同)时有多余的Y2O3成为晶界相,这主要是注射成形工艺中引入大量的残碳造成的.AIN晶界第二相的组成和分布对其热导性能有很大的影响,注射成形AIN陶瓷工艺中影响AIN热导率的关键因素是晶界第二相的分布和氧离子是否扩散进入晶格中.当Y2O3添加量为5%时,AIN中的晶界第二相主要为YN和Y2O3,样品具有最高的热导率167.5 W(m·K).     

La2O3在空气中稳定性的研究

通过对 L a2 O3 粉末在空气中吸水的增重测定及增重前后的 X射线衍射结构分析 ,发现 L a2 O3 吸水之后转变成 L a(OH) 3 。因此 ,L a2 O3 是一种化学性质不稳定的化合物 ,从前文献中关于“L a2 O3 是一种化学性质稳定的氧化物”的观点值得商榷。     

合成高活性Y_2O_3和Al_2O_3超细粉及Nd:YAG透明陶瓷

分别以Y(NO3)3和氨水、NH4Al(SO4)2·12H2O和碳酸氢铵为原料,采用化学沉淀法与碳酸铝铵分解法合成了高活性、平均粒径分别为39 nm和95 am的Y23和AlO3超细粉体.以Y2O3,Al2O3超细粉和商用Nd2O3粉体为原料,采用固相反应法,经1 700℃真窄烧结15 h,制备了Nd:YAG透明陶瓷.含x(Nd)=1%的YAG陶瓷在可见光区最大透光率约为53%.对YAG陶瓷的烧结过程和显微组织研究表明,Nd的引入明显地促进了陶瓷的烧结,同时晶粒得到细化.     

常温碳酸盐法合成高纯纳米Y2O3

直接采用工业中间体YCl3为原料,以非离子表面活性剂配制超微反应器,碳酸钠为沉淀剂合成得到纯度、粒度可控的单分散纳米Y2O3微粒.合成的Y2O3 纳米微粒为球状,统计平均粒径为30nm,纯度可达99.99%,比表面为60m2/g.研究表明原料浓度、表面活性剂浓度和煅烧方法影响Y2O3粒度大小和分散性.原料浓度在0.1mol/L～0.6mol/L,表面活性剂浓度1.2×10-3～6×10-3mol/L,梯度升温至700℃时,可得到纳米级Y2O3粉末.     

Y2O3对NiCr-Cr3C2金属陶瓷涂层热腐蚀性能影响行为研究

本文利用超音速火焰喷涂技术(HVOF),在20G钢表面制备了掺杂1wt.%、3wt.%、5wt.%三种不同含量Y2O3的NiCr-Cr3C2金属陶瓷复合涂层,并探究了其在650℃,Na2SO4/K2SO4熔盐环境中的热腐蚀性能。利用扫描电镜(SEM)、显微硬度计、拉伸试验机等对涂层的微观结构和力学性能进行了表征,利用X射线衍射仪(XRD)、拉曼光谱、X射线能谱仪(EDS)对复合涂层热腐蚀产物形貌、物相进行分析。结果表明掺杂1wt.%Y2O3的NiCr-Cr3C2复合涂层结构致密、孔隙率低、结合强度高,显微硬度达到801HV。热腐蚀过程中掺杂Y2O3的NiCr-Cr3C2复合涂层表面均生成耐蚀性良好且致密的Cr2O3膜。随着Y2O3掺杂量的增加,涂层的耐热腐蚀性能先升高后下降,当Y2O3掺杂量为1wt.%时,复合涂层表现出最佳的耐热腐蚀性能。     

Luminescent properties of amorphous phosphor 1.4Y2O3·2.5Al2O3·0.1Tb2O3 prepared by sol-gel method

Amorphous phosphor 1.4Y2O3·2.5Al2O3·0.1Tb2O3 (the same composition as Y2.8Tb0.2Al5O12) was prepared via a sol-gel method at relatively low temperature (i.c., below 650 ℃), which is much lower than that for the preparation of polycrystalline Y3Al5O12:Tb3 (above 1400 ℃). The amorphous phosphor prepared in the optimized conditions showed a bright green-yellowish luminescence, the intensity of which was comparable with that of polycrystalline sample and the emissions of which were assigned to 5D4→7Fj transitions of Tb3 . Besides the emissions of Tb3 , the amorphous samples prepared at temperatures below 500 ℃ presented a weak blue emission band around 420 nm.     

Microstructure and high-temperature properties of Fe-Ti-Cr-Mo-B-C-Y_2O_3 laser cladding coating

Fe-based composite coatings were fabricated on 5 CrNiMo die steel by laser beam melting a precursor mixture of ferrotitanium,ferrochromium,ferromolybdenum,B4 C and Y_2 O_3 powders.Micro structure and properties of the coatings were studied by X-ray diffraction(XRD),scanning electron microscopy(SEM),energy-dispersive spectrometer(EDS),resistance furnace and high-temperature tribometer.The results show that(Ti,Mo)C particles with flower-like and(Ti,Mo)B_2 with block-like shapes are in situ formed during laser cladding.Volume faction of multiple ceramic particles increases with the increasing of Y_2 O_3.The cumulative oxidation mass of the coating with 2 wt% Y_2 O_3 is decreased by one-third than that of the coating without Y_2 O_3.The oxidation layer of the coating with Y_2 O_3 is getting smooth.Meanwhile,high temperature wear volume loss of the coating with 2 wt% Y_2 O_3 is about 40% that of the coating without Y_2 O_3.The coating with 2 wt% Y_2 O_3 shows a smoother wear scar and few flat grooves are observed after high temperature wear test.     

A Study on La_2O_3-Y_2O_3-Mo Secondary Emission Material

Thephenomena ,mechanismandtheapplicationofsecondaryemissionofmanykindsofmaterialshavebeenstudiedsincethesecondaryemissionphenomenawasdiscoveredbyCompellin 1899.Withthedevel opmentofelectronictechnologythephenomenaofsec ondaryemissionhavebeenincreasinglyappliedinmanyfields[1,2 ] ,especiallyinhighpowermagnetrontube .Nowadays ,thecathodesofhighpowermag netrontubeusedinthefieldsofbroadcast,correspon denceandnationaldefensearemainlyBa Wcath odes[3] andsomeTh Wcathodes .However ,Ba Wcathodeishard…     

Synthesis and Property of H2La2Ti3O10/CdS Layered Nanocomposite Photocatalyst

H2La2Ti3O10/CdS nanocomposite with er photoactivity was synthesized by a stepwise exchange process from H2La2Ti3O10, which was obtained by H^＋ -exchanging reaction of H2La2Ti3O10 with HCl other than the normally used HNO3. The pillaring process was investigated by XRD, TEM, FT-IR and BET methods. The photocatalytic decomposition of aniline was used as the model system to evaluate the photochemical properties of H2La2Ti3O10/CdS,H2La2Ti3O10 and K2La2Ti3O10. It is found that the photoactivity of layered H2La2Ti3O10 is greatly improved by the intercalation of CdS in the interlayer. In general, the excellent photoactivity of the H2La2Ti3O10/CdS nanocomposite might be attributing to the extremely small particle size of incorporated CdS and good contact between CdS and La2Ti3O10^2- layers. On the other hand, the coupling of two semiconductor particles with different energy gap is useful to achieve effective charge separation. In H2La2Ti3O10/CdS, a photo-generated electron can transfer from CdS to the La2Ti3O10^2- layer, while the holes remain in the CdS particles. This helps to diffuse the electrons and holes before reaching the interface, and the holes and electrons can be effectively captured by the electrolyte in the solution. Simuhaneously, the optimal operating condition of photodecomposition aniline was investigated.     

ZrO_2-Al_2O_3(Y_2O_3)材料的相结构研究

本文通过X衍射技术和多晶法计算研究了ZrO_2-Al_2O_3和ZrO_2-Al_O_3-Y_2O_3陶瓷材料的相结构变化。结果表明,在ZrO_2-Al_2O_3体系中,在低Al_2O_3含量时,主要相是单斜相。随着Al_2O_3含量增大,单斜相比率系数X_m下降,四方相含量明显增大。在ZrO_2-Al_2O_3体系中添加Y_2O_3后,Y_2O_3可以促进形成四方相和稳定相系的作用,使三元系转变为四方结构。烧结温度对ZrO_2-Al_2O_3系相结构变化影响不明显,但对ZrO_2-Al_2O_3-Y_2O_3系影响较大,低Y_2O_3含量时,温度升高可促进相系的转移;而高Y2O_3含量时,已完全转变为四方结构。所以,烧结温度对相结构变化无影响。     

CaCl2-NaCl熔盐中La2O3电脱氧反应的电化学研究

采用熔盐电解法研究了La2O3电脱氧反应过程。由电位阶越实验及取样电流电位分析和对电解产物进行X衍射分析表明La2O3的电脱氧反应是可以进行的，La2O3得电子还原为低价脱氧产物LaO，接着LaO作为中间产物与阳极气体Cl结合生成氯氧镧。     

结合剂对铝镁浇注料抗渣性能的影响

利用SEM分析手段研究了铝镁浇注料的抗渣性能。发现在浇注料基质中尤其是在结合剂中应该降低SiO2和CaO的含量,减少砖层与渣层低熔点物质的生成,提高铝镁浇注料的抗渣侵蚀和渗透性能。     

Y2O3与MgO复合掺杂ZrO2材料的电性能研究

利用交流复阻抗分析技术对Y2O3与 MgO复合掺杂ZrO2材料的电性能进行了研究.发现随着Y2O3掺入量的增加,参与跃迁的氧空位增多,并促进烧结体的密度提高,气孔率降低,使得晶粒边界的电阻减少,导致(ZrO2)1-x-y(YO1.5)x(MgO)y陶瓷电导率增大.烧结温度的提高也是增加 (ZrO2 )1-x-y(YO1.5)x(MgO)y陶瓷电导率的重要因素之一.     

Effect of rare earth oxides on the properties of bio-soluble alkaline earth silicate fibers

Using natural mineral wollastonite, talc and quartz sands as raw materials, rare earth oxides(La_2O_3, Nd_2O_3 and Y_2O_3) as additives, the bio-soluble alkaline earth silicate fibers were prepared by melting and blowing process. The viscosity of the molten materials, bio-solubility and crystallization behavior of the fiber were investigated. The results indicated that the fiber drawing temperature range could be broadened since the slope of the temperature-viscosity curve decreased with adding rare earth oxide. The addition of rare earth oxide was beneficial to the increase of crystallization temperature by strengthening the network structure of the fiber. The existence of rare earth oxide in the fibers would reduce the solubility of the fibers, which still belonged to bio-soluble fibers.     

Study of Bi_2O_3-based Rare Earth Solid Electrolyte Used in Fuel Cell

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部分稳定氧化锆(PSZ)的化学稳定性研究

本文研究喷雾干燥法和无机胶化法制得PSZ粉末和陶瓷片,在不同介质及条件下Y_2O_3的溶解度。结果表明:PSZ粉末或陶瓷体在碱性介质中均稳定,不会发生Y_2O_3溶解。在水溶液中有少部分溶解。但在酸性介质中,PSZ粉末和陶瓷体中Y_2O_3均有明显的溶解。其溶解度是随着盐酸的浓度升高而明显增大,当盐酸浓度述3wt%时,Y_2O_3溶解量达到最高值。随着烧结温度升高,材料中Y_2O_3的溶解度明显下降。证实材料中Y_2O_3固溶ZrO_2较完全,只有微量游离Y_2O_3保留着,不影响材料的性能。喷雾干燥获得的粉末比胶化法的粉末,其Y_2O_3溶解度更低(0.3wt%);证明,喷雾法的PSZ粉比胶化法粉的化学稳定性高。