添加Y2O3对激光熔覆原位合成TiB2和TiC增强镍基复合涂层组织的影响

在Ti6Al4V合金表面激光熔覆原位合成了TiB2和TiC颗粒增强镍基复合涂层,通过X射线衍射仪、光学显微镜和扫描电镜以及能谱仪研究了添加2%(质量分数)Y2O3对涂层组织的影响。结果表明:未添加Y2O3的涂层由增强相、少量如CrB和基体组织组成;添加Y2O3后,涂层中增强相TiB2的尺寸显著细化且有新相Ni3Y生成,CrB化合物数量减少,涂层与基底形成冶金结合,且界面更平整、致密,成分过渡区有一定程度的缩小。     

WC添加量对等离子喷涂Mo2FeB2金属陶瓷涂层组织和耐腐蚀性能的影响

采用等离子喷涂法在Q235钢表面制备不同质量分数(0,10%,15%,20%,25%)WC改性Mo₂FeB₂金属陶瓷涂层,研究了WC添加量对涂层物相组成、显微组织和耐腐蚀性能的影响。结果表明：WC改性Mo₂FeB₂金属陶瓷涂层均主要由Mo₂FeB₂、WC、W₂C、铁和铁的氧化物相组成;当WC质量分数由0增加至15%时,金属陶瓷涂层的Mo₂FeB₂和WC双硬质相数量增多,尺寸减小,分布趋于均匀,当WC质量分数超过15%时,双硬质相发生聚集,孔隙率增大,涂层致密性下降;当WC质量分数为15%时,涂层组织最均匀致密,耐腐蚀性能最好。     

CeO2添加量对激光熔覆TiB2-TiC/Ni复合涂层组织和性能的影响

利用激光熔覆技术在TC4钛合金表面制备了添加质量分数1.0%,1.5%,2.0%CeO₂的TiB₂-TiC/Ni复合涂层,研究了复合涂层的物相组成、显微组织和硬度,讨论了搭接率(30%,40%,50%)对最佳CeO₂含量条件下复合涂层试样摩擦磨损性能的影响。结果表明：复合涂层均由TiB₂、TiB、α-Ti、TiC、Ni₃Ti、Cr₂₃C₆、Ti₂Ni、Cr₃C₂、γ-Ni等相组成;添加质量分数1.5%CeO₂复合涂层的组织最为均匀致密,细化效果明显;随着CeO₂添加量的增加,复合涂层的硬度先增后降,添加质量分数1.5%CeO₂复合涂层的硬度最高,约为1 015 HV。CeO₂的最佳添加质量分数为1.5%,在此条件下随着搭接率的增加,试样的磨损质量损失先减小后增大,当搭接率为40%时,...     

Y_2O_3对镍基碳化钛金属陶瓷熔覆层组织的影响

利用 HTWY180-MK 激光焊接机在45*钢基体表面熔覆了含Y2O3,的镍基 TiC 金属陶瓷复合涂层,研究了稀土Y2O3,对激光熔覆镍基金属陶瓷复合涂层组织及性能的影响.结果表明:在镍基金属陶瓷复合层中加入一定量的稀土氧化物Y2O3,可有效改善熔覆层的组织及性能,减少复合涂层中的裂纹、孔洞、杂质,加速熔覆层中 TiC 颗粒的溶解,并改善了 TiC 颗粒的形状,同时使得激光熔覆层的组织及硬度更加均匀.在本文所述试验条件下,熔覆层中添加稀土氧化物Y2O3,最佳质量分数为0.5%.     

电泳-电镀沉积制备纳米Al_2O_3颗粒增强镍基复合镀层的耐磨性能

先采用电泳沉积工艺在铜基体上均匀沉积了粒径为20 nm的Al2O3涂层,然后采用电镀技术在Al2O3涂层中沉积金属镍,得到具有较高含量的纳米Al2O3增强镍基复合镀层;用扫描电镜及附带的能谱仪分析了镀层的表面形貌及成分,研究了镀层在干摩擦条件下的摩擦磨损性能,并对其磨损机理进行了探讨.结果表明:相比于纯镍镀层,纳米Al2O3颗粒增强镍基复合镀层的表面更加平整光滑,组织更加致密均匀;镀层中纳米Al2O3颗粒含量对镀层耐磨性能具有显著影响,当其体积分数约为30%时,镀层的耐磨性能最好.     

Stellite6/WC复合涂层微观组织和性能研究

采用激光熔覆技术在Q960钢板表面熔覆Stelllite6耐腐蚀涂层,为提高涂层的耐磨性能,分别向涂层中加入质量分数为15%、20%、30%、35%和40%的WC粉末。并采用金相显微镜、XRD、显微维氏硬度计和电化学工作站对复合涂层的微观组织形貌、物相、显微硬度和电化学性能进行测试分析。研究结果表明:随WC含量增加,复合涂层生成钴碳复杂相,并出现少量气孔和裂纹,涂层耐磨性能明显提高,与之相反,复合涂层的耐腐蚀性能不断恶化。综合分析涂层的耐磨和耐腐蚀性能,加入30%WC的涂层综合性能最佳。     

二硅化钼对镍铝涂层显微组织和性能的影响

在镍包铝粉体中添加MoSi2,采用等离子喷涂方法制备了镍铝涂层,研究了MoSi2对镍铝涂层的组织、显微硬度和摩擦磨损性能的影响,并分析了涂层的磨损机理。结果表明:加入MoSi2后,镍铝涂层主要由Ni3Al、NiAl、MoSi2和Mo5Si3相组成;随着MoSi2含量的增加,涂层中孔隙、微裂纹的数量及尺寸增加,显微硬度也逐渐增大;加入质量分数为20%的MoSi2后涂层的耐磨性最好;纯镍铝涂层的磨损机理为磨粒造成的犁削,加入20%MoSi2后涂层的磨损机理为碾压作用和少量的脆性断裂,加入50%MoSi2后涂层主要为脆性断裂。     

以粉煤灰和Al-TiO_2-B_2O_3为原料制备玻璃/陶瓷复合涂层的组织及耐磨性能

以粉煤灰为主要原料,并添加质量分数为10%的Al-TiO2-B2O3,采用热化学反应法在Q235钢基体上制备了玻璃/陶瓷复合涂层(放热体系涂层),研究了该涂层的物相组成、截面形貌、抗热震性能、显微硬度以及耐磨性能;并制备了不添加Al-TiO2-B2O3的常规粉煤灰玻璃/陶瓷复合涂层作为对比涂层。结果表明:放热体系涂层中产生了NaB15、TiB2、Na2B4O7、Ca2Al2SiO7等新相,涂层界面结合良好,显微硬度最高可达到700HV0.1,在700℃室温的热震次数可达50次以上;其耐磨性能相对Q235钢和常规玻璃/陶瓷涂层的分别提高了9.67倍和0.63倍。     

NiCrAlY合金粉添加量对超音速火焰喷涂WC-10Co4Cr涂层组织及性能的影响

在WC-10Co4Cr金属陶瓷粉中添加不同质量分数(0,6.5%,10.0%,20.0%)NiCrAlY合金粉,采用超音速火焰喷涂技术在316L不锈钢基体表面制备NiCrAlY/WC-10Co4Cr金属陶瓷涂层,研究了合金粉添加量对涂层显微组织、显微硬度和耐腐蚀性能的影响。结果表明:不同合金粉添加量下所得涂层的显微组织均主要由WC相组成;随着合金粉添加量的增加,涂层中的镍和Ni3Al相含量增多,孔隙率和硬度下降,耐腐蚀性能先增后降;当合金粉质量分数为6.5%时,涂层的硬度分布最均匀,耐腐蚀性能最好。     

原位反应结合热压烧结工艺制备Al_2O_3/Fe-28Al-5Cr复合材料的组织和性能

采用原位反应结合热压烧结工艺制备了Al2O3质量分数为10%和20%的Fe-28Al-5Cr基复合材料,研究了它们的物相、显微组织、力学性能,以及室温和200,400,600,800℃下的摩擦磨损性能,并与采用外加Al2O3方法制备的相同复合材料进行了对比。结果表明:原位合成Al2O3制备的复合材料由Fe3Al和Al2O3两相组成,Al2O3主要分布在晶界处;随着Al2O3含量的增多,复合材料的硬度逐渐增大,抗弯强度明显降低;当Al2O3质量分数为20%时,复合材料的耐磨性能得到了明显改善;与外加20%Al2O3制备的复合材料相比,原位合成Al2O3制备的复合材料具有较高的硬度和强度,在室温和200,800℃下的磨损率稍低。     

Na2O-B2O3-Ta2O5系统玻璃红外光谱的研究

本文首次系统地研究了Na₂O—B₂O₃—Ta₂O₅。三元新系统的红外光谱,分析了B₂O₃、Ta₂O₅含量的变化对玻璃结构的影响。结果表明:随着Na₂O/B₂O₃比值的减小,结构中:[BO₄]四面体减小,[BO₃]三角体增加。随着Ta₂O₅含量的增加,[BO₄]四面体的数量增多,非桥氧的数量减少,表明Ta⁵⁺可以连结非桥氧,形成网络。     

B2O3—La2O3—BaO—Nb2O5系统的玻璃生成范围及其性质

本文研究了在B₂O₃-La₂O₃-BaO-Nb₂O₅四元系统中当B₂O₃含量分别为25、30、35wt%时,该系统的玻璃生成范围和它们的光性、密度等变化规律。结果表明,随着B₂O₃含量的增加,系统的玻璃生成范围向贫Nb₂O₅边界扩充,富Nb₂O₅边表现收缩。工作中得出了该系统分别以SiO₂代B₂O₃、Al₂O₃代BaO后的析晶、折射率、色散及密度等性质的变化规律。最后应用该系统研制定型了713/538玻璃。     

Electron and light microscopy studies on the domain structures of Zn3B7O13Cl, Zn3B7O13Br and Zn3B7O13I ferroic boracites

The domain structures of Zn₃B₇O₁₃Cl, Zn₃B₇O₁₃Br and Zn₃B₇O₁₃I boracite single crystals were studied by means of polarized light in conjunction with electron microscopy. Single crystals of the three compositions were grown by chemical transport reactions in closed quartz ampoules, at a temperature of 900 °C and were examined by polarizing optical microscopy (PLM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). For both PLM and SEM, the same as‐grown samples were used without having to resort to metallization of the crystal faces. For TEM the single crystals were crushed and mounted on holey carbon films. Comparative electron microscope images were useful for revealing the domain structure of these ferroelectric/ferroelastic materials previously observed between the crossed polars of an optical microscope. X‐ray diffraction analysis of the pulverized crystals was performed for this triad of halogen boracites containing zinc as a common metal.     

Ta2O5对B2O3-La2O3-CaO系统玻璃生成范围的影响

本文研究了在B₂O₃—La₂O—CaO三元系统中,当Ta₂0₅的含量分别为5、10、15、20wt%时,该系统的玻璃生成范围.结果表明,随着Ta₂O₅含量的增加,系统的玻璃生成范围向贫B₂O₃,富La₂O₃边界扩充.当Ta₂O₅的含量为10wt%时,玻璃的生成区域最大.通过差热分析确定了玻璃析晶温度,并用X射线衍射进行了物相鉴定.结果表明,随Ta₂O₅取代La₂₃其主结晶相的放热峰或吸热峰的位置变化不同,所析出的结晶物质亦不同.     

Nb2O5-B2O3-K2O系统玻璃的结构与性质

本工作用大功率转靶 X 射线衍射仪研究铌硼酸盐玻璃结构;根据 B·E·War-ren 方程,建立了一种计算玻璃原子径向分布函数(RDF)的解析方法。因其涉及因素少,计算简便,适用于多元系统玻璃结构分析。应用本方法,已获得了 Nb-B-K 系统玻璃的比较完整的三维结构模型。模型表明,这种玻璃结构松散,克分子体积比较大,并具有较高的自激发极化率。于是铌硼酸盐玻璃的低密度、低折射率和相对高的色散,以及较高的电导率等特殊性质的结构因素得到了证实。     

Tribological performance of MoS2---B2O3 compacts

A recent investigation suggests that selected oxides perform well as additives in molybdenum disulphide (MoS₂) because of their ability to soften at asperity contacts with the result that the solid lubricant can attain and retain a preferred tribological orientation.This research determined the effectiveness of boric oxide (B₂O₃), when used as an additive in MoS₂, for substrate temperatures ranging from 21°C to 316°C. This range was used to allow the asperity contact temperature to vary below and above the softening point of B₂O₃. It was found that a moderate friction coefficient and high wear, which is attributed to the additive acting abrasively, occurred when the asperity contact temperature was well below the softening point of the oxide. When the asperity contact temperature neared the softening point of the oxide, the friction coefficient increased dramatically and wear volume was reduced. It is postulated that B₂O₃ acted adhesively at the interface resulting in a higher coefficient of friction, and wear decreased due to an attainment of a preferred orientation by the MoS₂. For asperity contact temperatures significantly above the softening point of B₂O₃, the friction coefficient returned to about the same value as for temperatures below the softening point. It is speculated that wear continued to increase moderately because of localized melting of the B₂O₃, permitting the MoS₂ to be removed from the interface. These observations support a hypothesis that an additive, such as boric oxide, can soften as the asperity contact temperature approaches the softening point temperature of the additive so that the overall tribological conditions may be improved resulting in reduced interfacial wear. Significant changes in temperature, load or sliding velocity would, of course, dramatically alter the wear characteristics observed at the interface.     

基于Ge2Sb2Se4Te1的可重构光开关的仿真

光开关是集成光路上一个重要的元器件。提出了一种用在L和C波段基于硫系相变材料（Ge₂Sb₂Se₄Te₁）的片上2×2定向耦合器式的可重构光开关,可通过改变相态切换开关。利用仿真软件Lumerical中的Mode Solutions和FDTD Solutions模块设计器件,得到在1500~1625 nm内耦合长度为24.9 μm的Ge₂Sb₂Se₄Te₁非晶态下插入损耗（IL）>-0.36 dB,串口对比度（CT）<-24 dB;Ge₂Sb₂Se₄Te₁晶态下IL>-0.44 dB,CT<-30.46 dB。利用仿真软件COMSOL模拟532 nm波长激光加热Ge₂Sb₂Se₄Te₁,结果显示：一个25 ns、峰值功率45 mW的高斯短脉冲可以使材料由晶态转化为非晶态;施加多个峰值功率20 mW、周期1 μs且占空比0.03%的高斯脉冲阵列可重回晶态。仿真结果表明,设计的光开关在通信波段通过激光加热可以快速实现切换光路的作用。     

Al2O3-TiB2-ZrO2三元复合陶瓷刀具的性能研究

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Characterization of cast Al86Mn3Be11 alloy

An Al₈₆Mn₃Be₁₁ alloy cast into copper mould was subjected to metallographic investigation. The as-cast microstructure consisted of a quasicrystalline icosahedral phase (i-phase), Be₄AlMn phase and, occasionally, a hexagonal phase. Al-rich solid solution represented the dominant phase. The chemical compositions of phases were determined using AES. The composition of the Be₄AlMn slightly deviated from the stoichiometric composition, whereas the composition of the i-phase was approximately Al₅₂Mn₁₈Be₃₀, containing an appreciable amount of Be. The average composition of the hexagonal phase was Al₆₆Mn₂₁Be₁₃. Deep etching and particle extraction provided a deep insight into the three-dimensional morphology of the i-phase and the hexagonal phase, whereas Be₄AlMn was slightly attacked by the etchant. The i-phase was present predominantly in the form of dendrites and a rodlike eutectic phase. The hexagonal phase was primarily in the form of hexagonal platelets, whereas Be₄AlMn was rather irregular in shape. The morphology of the i-phase can be explained by predominant growth in 3-fold directions and the lowest energy of the 5-fold planes, leading to the faceting and adopting a pentagonal dodecahedron shape. The brightnesses of phases in the backscattered electron images were rationalized by determining their backscattering coefficients. TEM investigation showed considerable phason strain in the i-phase, and the polycrystalline nature of the Be₄AlMn phase.     

永磁同步电机积分滑模观测器控制

对永磁同步电机观测器控制进行研究,针对传统滑模观测器存在控制精度低、系统抖振较大的不足,设计了一种永磁同步电机积分滑模观测器控制。积分滑模控制具有控制精度高、系统抖振小的特点。积分滑模观测器可以有效提高电机控制精度,增强控制系统抗干扰能力。采用饱和函数代替符号函数进行滑模控制律设计,降低控制系统固有抖振,使滑模控制动态性能提高。通过仿真验证了积分滑模观测器控制策略的可行性。