热障涂层用稳定ZrO_2基陶瓷材料研究现状

综述了氧化物稳定的热障涂层用ZrO2陶瓷的研究现状.氧化物稳定ZrO2陶瓷材料主要适用于在1000℃左右工作的热障涂层,而不宜用作新型高温热障涂层表面陶瓷层材料.随着航空发动机技术的发展,稀土铈酸盐陶瓷材料有望替代氧化物稳定的ZrO2陶瓷.根据声子导热理论和晶体化学原理,选用合适的氧化物对稀土铈酸盐陶瓷材料进行掺杂,可进一步降低其热导率并改善热膨胀系数,这将为热障涂层技术应用开辟广阔的空间.     

热障涂层用稳定ZrO2基陶瓷材料研究现状

综述了氧化物稳定的热障涂层用ZrO2陶瓷的研究现状．氧化物稳定ZrO2陶瓷材料主要适用于在1000℃左右工作的热障涂层,而不宜用作新型高温热障涂层表面陶瓷层材料．随着航空发动机技术的发展,稀土铈酸盐陶瓷材料有望替代氧化物稳定的ZrO2陶瓷．根据声子导热理论和晶体化学原理,选用合适的氧化物对稀土铈酸盐陶瓷材料进行掺杂,可进一步降低其热导率并改善热膨胀系数,这将为热障涂层技术应用开辟广阔的空间．     

热处理对热障涂层材料Y_2O_3部分稳定ZrO_2性能的影响

热障涂层用于燃气轮机的热端部件,可以显著提高其使用温度,延长热端部件的使用寿命,并增大燃气轮机发动机的效率.利用Y2O3和ZrO2为原料,通过固相合成法合成了Y2O3(w(Y2O3)=6%~8%)部分稳定的ZrO2(Y-PSZ)热障涂层陶瓷顶层,并对此陶瓷顶层的微观形貌、相组成进行了研究.同时研究了热处理对热障涂层材料Y-PSZ性能的影响.     

稀土Y2O3和Gd2O3共掺杂对La2 (Zr0.7Ce0.3)2O7陶瓷相结构及热膨胀系数的影响

采用固相合成法制备了(La1-2xYxGdx)2(Zr0.7Ce0.3)2O7(x=0,0.30,0.35,0.40,0.45,0.50)体系陶瓷材料.分别利用XRD、扫描电子显微镜和高温热膨胀仪对陶瓷材料的相组成、微观形貌及热膨胀系数进行测试.结果表明.掺杂量x=0时为立方烧绿石结构,x≥0.30时为立方萤1石结构;晶粒发育良好,晶界清晰;Y2O3和Gd2O3的掺杂可以有效的提高La2 (Zr0.7 Ce0.3)2O7的热膨胀系数.     

等离子喷涂纳米ZrO2功能梯度热障涂层组织结构

采用大气等离子喷涂技术制备了纳米氧化锆功能梯度热障涂层,运用XRD、SEM等手段分析了粉末与涂层的组织结构和相组成．结果表明,喷涂前后,粉末相成分未发生变化,仍然是四方相和立方相组成的混合体;表面陶瓷层和次表层的孔隙率分别为8．2％和5．15％;涂层的晶粒主要分布在20nm～120nm之间,晶粒发育良好,涂层结合强度约为23．4MPa．     

螺杆泵螺杆纳米掺杂陶瓷涂层显微结构研究

利用大气等离子喷涂技术(APS),在7.5 m螺杆泵螺杆基体表面上制备纳米掺杂30%AT13(Al2O3 13% TiO2)陶瓷涂层,采用Philips XL-30型扫描电镜(SEM)、能谱(EDS)和Philips X-port型X射线衍射仪(XRD)等现代分析手段对纳米掺杂AT13等离子喷涂粉末及螺杆表面等离子喷涂涂层的显微组织、物相进行了观察测定.结果表明:纳米掺杂等离子喷涂粉末结构呈微米级粒子表面包覆纳米粒子的麻团状,尺寸在50～70 μm内,流动性好,适用于大气等离子喷涂.纳米掺杂使等离子喷涂涂层元素分布均匀性提高,孔隙度降低,涂层内出现(Al2O3)5.333与斜方晶态的Al2TiO5物相.涂层断口分析证明:在纳米掺杂30%的涂层中,出现大量直径约为10 nm的蠕虫状晶须,断裂方式变为韧性的穿晶断裂,为纳米掺杂螺杆使用寿命成倍的提高提供了理论依据.     

Ti（C,N）-Al2O3复合涂层深冷处理的微观组织及力学性能

对YBM253涂层硬质合金进行了-196℃下不同时间（0、24、30、36、48 h）的深冷处理,利用掠入射X射线衍射方法分析了不同深冷时间下Ti（C,N）-Al₂O₃涂层的相结构变化,通过扫描电子显微镜（SEM）观察了不同深冷时间涂层的断口形貌,并且对不同深冷时间的试样进行了硬度和膜基结合力的检测和分析。结果表明:深冷处理对试样的硬度和膜基结合力都有一定的影响,30 h是深冷处理最佳的工艺时间,可获得最佳的综合力学性能。其性能变化的主要原因是经过深冷处理Ti（C,N）-Al₂O₃涂层产生了亚稳相κ-Al₂O₃与稳定相α-Al₂O₃之间的转变,深冷处理会导致不同热膨胀系数的基体和涂层产生内应力的变化。 更多还原     

Effect of microstructure on the mechanical,thermal, and electronic property measurement ofceramic coatings

Ceramic materials were investigated as thermal barrier coatings and electrolytes. Electrophoretic deposition（EPD） and physical vapor deposition（PVD） were employed to fabricate samples, and the mechanical properties and microstructure were examined by nanoindentation and microscopy, respectively. Yttria-stabilized zirconia/alumina（YSZ/Al2O3） composite coatings, a candidate for thermal barrier coatings, yield a kinky, rather than smooth, load–displacement curve. Scanning electron microscope（SEM） examination reveals that the kinky curve is because of the porous microstructure and cracks are caused by the compression of the indenter. Li0.34La0.51 Ti O2.94（LLTO） on Si/Sr Ru O3（Si/SRO） substrates, an ionic conductor in nature, demonstrates electronic performance. Although SEM images show a continuous and smooth microstructure, a close examination of the microstructure by transmission electron microscopy（TEM） reveals that the observed spikes indicate electronic performance. Therefore, we can conclude that ceramic coatings could serve multiple purposes but their properties are microstructure-dependent.     

梭形Fe_5(PO_4)_4(OH)_3·2H_2O的一步水热法制备及生长机理研究

采用可控的一步水热法制备出了具有对称棱边的梭形Fe5(PO4)4(OH)3·2H2O产物。利用X-射线衍射、场发射扫描电子显微镜、透射电子显微镜等手段对产物进行了表征,发现产物的生长机理符合Ostwald熟化过程。研究表明:在180℃下反应96h后会得到多臂形貌的纯相Fe5(PO4)4(OH)3·2H2O产物,且在低温下更容易获得纯相的Fe5(PO4)4(OH)3·2H2O梭形产物。此外研究发现,产物在500℃热处理后具有较好的形貌和尺寸上的热稳定性。     

Y3+取代Bi3+对Bi2(Zn1/3Nb2/3)2O7陶瓷烧结温度的影响

采用固相反应制备Bi2(Zn1/3Nb2/3)2O7微波陶瓷,并借助X射线、扫描电镜、LCR4284测试仪,研究Y3 取代Bi3 对Bi2(Zn1/3Nb2/3)2O7陶瓷烧结特性及介电性能的影响。研究结果表明:随着Y3 替代量的增加,晶粒尺寸减小,介电常数先减小后增大,烧结温度升高;适量的Y3 替代可以获得性能很好的BZN介质材料。     

The structure and properties of Ag(Nb0.8Ta0.2)O3 ceramic doped with MnNb2O6

The influences of doping of MnNb2O6 on the structure and dielectric properties of Ag(Nb0.8Ta0.2)O3 were illustrated. Ag(Nb0.8Ta0.2)O3 samples doped with different amount of preformed MnNb2O6 (1 mol%, 2 mol%, 3 mol%, 4 mol%, 6 mol%, 8 mol%) were prepared by traditional solid-state reaction method and characterized by XRD, SEM and EDS, and the dielectric properties of samples were compared. The experiment results indicated that when the doping amount of MnNb2O6 was greater than 3 mol%, second phase appeared because of the solid solution limit. The permittivity of the Ag(Nb0.8Ta0.2)O3 samples doped with MnNb2O6 firstly increased and then decreased with the sintering temperature, while the dielectric loss decreased first, and then increased slightly. 1 100 ℃ seems to be the most proper sintering temperature for most of the samples. When the amount of MnNb2O6 is about 3 mol%, the samples have the best dielectric properties, larger permittivity and smaller dielectric loss.     

Corrosion resistance of plasma sprayed NiCrAl (ZrO_2 Y_2O_3) thermal barrier coating on 18-8 steel surface

1INTRODUCTION Austeniticstainlesssteelisdevelopedtocom pensateforpoorcorrosionresistanceofmartensite stainlesssteelandoverlargebrittlenessofferrite stainlesssteel.Basicconstituentsofitstypicalal loyare18%Crand8%Ni(massfraction),which isusuallycalledas188s…     

A new sol-gel process for preparing Ba（Mg1／3Nb2／3）O3 nanopowders

Commercially available niobium (V) oxide [Nb2O5], with barium acetate [Ba(CH3COO)2] and magnesium acetate [Mg(CH3COO)2·4H2O] was used as the starting material in the sol-gel process for preparing Ba(Mg1/3Nb2/3)O3 (BMN) nanopowders. At first, Nb2O5 reacted with melting sodium hydroxide and transformed into dispersible oxide. The resulting glassy substance after cooling was dispersed and washed several times in distilled water to remove the Na ions. The as-prepared colloidal Nb2O5·nH2O was subsequently mixed with acetic solution of barium acetate and magnesium acetate according to the required molar proportions and followed by gelation. The ultrafine BMN powders were finally obtained after heat-treating the gel at 820℃ for 1 h, and the as-sintered nanoceramics revealed a high relative density of 98.2%, and a high microwave Q-factor, of 10397 at 1.45GHz.