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.     

机械活化-放电等离子烧结制备Y3Al5O12陶瓷

以高纯Y2O3和Al2O3粉体为原料,通过机械活化和放电等离子烧结制备Y3Al5O12(YAG)陶瓷.研究结果表明:机械活化Y2O3和Al2O3粉体,不但细化了Al2O3颗粒,而且使Y2O3发生了晶态转变,由立方晶转变为斜方晶,并最终非晶化;机械活化过程最终还合成了过渡产物YAlO3(YAP),但球磨5h后,继续延长球磨时间,会引入大量ZrO2杂质;球磨处理的Y2O3和Al2O3粉体具有很高的活性,能促进在较低温度下通过放电等离子烧结合成YAG.对球磨5h的粉体在不同温度进行放电等离子烧结的研究表明,在1000℃可获得纯YAG陶瓷,在1 400℃可得到相对密度为99.4%、晶粒大小为1～2μm的YAG陶瓷.     

Al2O3含量对Al2O3弥散强化铜基复合材料性能的影响

探索了在不同浓度的Al（NO3）3溶液中加入铜粉，搅拌至糊状，在80℃干燥后，在H2保护气氛下加热至500℃使得Al（NO3）3分解成Al2O3，所得粉末在真空烧结机中加热到800℃，制备出Al2O3弥散强化铜基复合材料的新型工艺．研究了Al2O3含量对该复合材料各种性能的影响规律，结果表明：随着Al2O3含量的增加，材料的导电率下降；当Al2O3含量达1．0％时，材料的硬度达到最大值，而密度随Al2O3含量的增加而下降。     

Al2O3/ZrO2(Y2O3)共晶复合陶瓷晶体生长机理

基于国外定向凝固氧化物/氧化物共晶复合陶瓷的晶体生长动力学行为的研究成果,阐述其动力学机制,分析动力学因素对微观结构形态的影响,探讨晶体生长热力学、动力学行为与微观结构形态之间的关系,同时结合以燃烧合成、快速凝固技术制备的新型高强韧Al2O3/ZrO2(Y2O3)共晶复合陶瓷,探讨共晶复合陶瓷在快速凝固条件下的晶体生长动力学行为.结合定向凝固与快速凝固两种晶体生长机制,得知过冷度、凝固界面前沿的温度梯度是影响晶体生长方式的重要因素,且受二者决定的凝固速率(即晶体生长速率)则决定材料的最终微观结构与形态.     

Al2O3/AlTiC/ZrO2/透辉石陶瓷材料的力学性能及微观结构

将金属Al、Al3Ti和TiC以AlTiC中间合金的形式以及ZrO2颗粒共同引入Al2O3基体材料中,热压制备了Al2O3/TiC/ZrO2/AlN复合材料.在此基础上,添加(体积分数)1%透辉石作为烧结助剂,以实现复合材料的液相烧结并促进其致密化程度.复合材料在烧结过程中有新相AlN生成;同时Al、TiC以及Al3Ti释放的Ti原子发生原子重组生成Al2Ti4C.对热压后材料的硬度、断裂韧度和抗弯强度进行了测试和分析;探讨了透辉石对材料致密化程度及力学性能的影响效果;研究了复合材料断面断裂方式的变化对其力学性能的影响;并对AlTiC中间合金的细化特性进行了分析.     

Al2O3的掺杂浓度对Ce0．8Y0．2O1．9电解质的性能影响研究

利用低温燃烧合成法制备了Al2O3掺杂浓度为0.5%～10%(摩尔分数,以下同)的Al2O3/Ce0.8Y0.2O1.9固体电解质复合材料。研究了Al2O3掺杂浓度对Ce0.8Y0.2O1.9固体电解质烧结及电性能的影响。试验结果表明,添加少量的Al2O3可以改善Ce0.8Y0.2O1.9固体电解质的烧结性能,当Al2O3的添加量为0.5%时,电解质粉体具有最佳的烧结性能,1350℃时的相对密度达到99%以上。当Al2O3的掺杂浓度超过其在Ce0.8Y0.2O1.9中的溶解极限时,随Al2O3掺杂量的继续增加,烧结体的相对密度开始下降。阻抗谱结果表明,在溶解极限范围内,Al2O3使Ce0.8Y0.2O1.9的电导率减小,电导活化能增加。Al2O3的掺杂浓度超过溶解极限时,Ce0.8Y0.2O1.9的晶粒电阻不变,由于Al2O3对晶界的"清洁"作用,晶界电阻减小;当Al2O3的掺杂浓度超过5%时,由于Al2O3颗粒对晶界的"阻塞"作用,晶界电阻增加。     

机械活化-放电等离子烧结FeAl/Al2O3复合材料

利用机械活化-放电等离子烧结的方法,将Fe-Al-Al2O3粉末经机械活化后快速烧结,得到致密且晶粒细小的FeAl/Al2O3,块体复合材料.研究表明,在球粉质量比13:1、转速170r/min、球磨时间25h的球磨条件下,Fe-40%(原子数分数)Al-10%(质量分数)Al2O3粉体中的纳米级Al2O3颗粒,在细化和活化Fe、Al金属粉末的同时,还能有效地阻止金属粉末在烧结前合金化生成金属间化合物.在烧结压力40MPa、烧结温度1 050℃、加热时间15min、保温时间10min的工艺条件下,制备的FeAl/Al2O3复合材料的相对密度达96.4%.     

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.     

微波辐射法制备Y2O3:Eu3+红色荧光粉

通过正交试验确定了微波辐射法合成Y2O3:Eu3+红色荧光粉的最佳工艺条件,即升温速率20℃/min,煅烧温度1 240℃,保温时间60 min,此条件下所制备样品的相对亮度达107.0%.对样品进行物相、粒度及光谱分析,结果表明该样品为单一纯相Y2O3,粉末粒度均匀,D50为3.28μm,其最大发射光谱峰位于607 nm处,色坐标为x=0.653 3、y=0.342 4.     

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.     

Thermal Shock Resistance of Al2 O3/ZrO2 (Y2O3) Composites

ZrO₂ containing 2% (mol fraction) Y₂O₃ and 3% (mol fraction) Y₂O₃ were added into Al₂O₃ matrix, compositing composites with 15% volume fraction of addictives mentioned above. The testing of property and analysis of SEM presented that, after vacuum sintering at 1550 °C, thermal shock resistance of two composites was superior to Al₂O₃ ceramic. The experiment showed that the properties of Al₂O₃ composites was higher than Al₂O₃ ceramic, and Al₂O₃/ZrO₂(3Y) was higher than Al₂O₃/ZrO₂(2Y) in thermal shock resistance. Improvement of thermal shock resistance of composites was attributed to many toughness machanisms of ZrO₂(Y₂O₃). By calculation, the fracture energy of Al₂O₃, Al₂O₃/ZrO₂ (2Y) and Al₂O₃/ZrO₂(3Y) was 38100.8 and 126.2 J·m⁻², respectively. Cracks initiation resistance (R') of Al₂O₃/ZrO₂(3Y) and Al₂O₃/ZrO₂(2Y) was higher than Al₂O₃ ceramic by 1.57 and 1.41 time, respectively, and cracks propagation resistance (R″″) was higher than Al₂O₃ ceramic by 1.46 and 1.38 time, respectively, which was corresponding to the results of residual strength.     

Investigation on pumping oxygen characteristics of (Bi2O3)0.73(Y2O3)0.27 solid electrolyte

(Bi2O3)0.73(Y2O3)0.27 fine powders prepared by wet chemical precipitation method were cold isostatically pressed to form solid electrolyte tubes, and sintered at 900 ℃ for 10 h in the air. Their pumping oxygen characteristics in non-dehydrated Ar gas were investigated, where a ZrO2 (Y2O3 stabilized) oxygen sensor was used to measure the oxygen partial pressure Po2. The results showed that the Po2 value reached magnitudes of 1×10-20-1×10-10 Pa at the applied pumping oxygen voltage of 0.5 V, 1×10-37-1×10-27 Pa at 1.0 V and 1×10-53-1×10-47 Pa at 2.0 V within the temperature range from 550 to 650 ℃. Moreover, no cracks were found in the tested solid electrolyte tubes. Thus, the Bi2O3-Y2O3 system might be used in solid electrolyte oxygen pump for purifying gases.     

Oxidation Resistance of Fe-13Cr Alloy with Micro-Laminated （ZrO2-Y2O3 ） / （Al2O3-Y2O3 ） Films

Oxidationofmetalsoralloysathightemperatures canbetreatedasaspecialcaseofmetalliccorrosion,inwhichsolidphasesinteracteitherwithaliquid agentoragaseousagent.Toimprovetheresistance againsthigh temperatureoxidationandelectrochemical corrosionofmetals,thesurfa…     

Mechanochemical Effects in Ln_2O_3-Ln(OH)_3-(H_2O)(Ln=La,Nd) System

ＭｅｃｈａｎｏｃｈｅｍｉｃａｌＥｆｅｃｔｓｉｎＬｎ２Ｏ３Ｌｎ（ＯＨ）３（Ｈ２Ｏ）（Ｌｎ＝Ｌａ，Ｎｄ）ＳｙｓｔｅｍＤｉｍｉｔｒＴｏｄｏｒｏｖｓｋｙ，ＡｔａｎａｓＴｅｒｚｉｅｖ（ＦａｃｕｌｔｙｏｆＣｈｅｍｉｓｔｒｙ，ＵｎｉｖｅｒｓｉｔｙｏｆＳｏｆｉａ...     

Amorphized powders of eutectic composition in the Al2O3-ZrO2(Y2O3) system

Translated from Poroshkovaya Metallurgiya, No. 1(325), pp. 4–8, January, 1990.     

Determination of the standard gibbs energy for the reaction of 3BaO (s) + 2Cr (s) + 3/2O2 (g) = 3Ba0 · Cr2O3 (s)

The standard Gibbs energy of formation of 3BaO · Cr₂O₃ has been measured by a chemical equilibrium technique and is expressed as follows: 3BaO (s) + 2Cr (s) + 3/2 O₂ (g) = 3BaO · Cr₂O₃ (s) ΔG^o = -1,260,000 (±3000) + 282 (±24)r(J/mol) The activity coefficient of chromium in copper, which was needed for the foregoing measurement, may be expressed by the following equation: 5790 log γ _Cr ^{o =5790/T-2.10} The value of standard Gibbs energy at 1573 K was found to be close to that of reaction of formation of CaO · Cr₂O₃ expressed in the similar form. The BaO saturated BaF₂ flux is shown to be far more promising in the oxidative dephosphorization of chromium-containing hot metal in comparison with the CaO-SiO₂-CaF₂ flux doubly saturated with CaO and 3CaO-Cr₂O₃.     

Measuring and Modeling Viscosity of CaO-Al2O3-SiO2(-K2O) Melt

The effect of K₂O on viscosity in CaO-SiO₂-Al₂O₃ melt has been measured by a rotating spindle viscometer. It is indicated from the experimental results that viscosity first increases then decreases with the increasing content of K₂O; the maximum viscosity occurs in the field of K₂O/Al₂O₃?>?1. After gradually adding K₂O, the transformation of bridging oxygen (from being bonded with Al³⁺ ion charge compensated by Ca²⁺ ion to that compensated by K⁺?ion, for the higher priority of K⁺ ion relative to Ca²⁺ ion) increases the viscosity, whereas the increase of content of nonbridging oxygen decreases viscosity. The two factors lead to the complicate variation behavior of viscosity. The viscosity model proposed in our previous papers describes this phenomenon well.