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,...     

高速电弧喷涂FeAlCrNi-Cr3C2涂层的组织与相结构研究

采用粉芯丝材高速电弧喷涂技术制备了FeAlCrNi-Cr3C2涂层,并研究了涂层的组织和相结构.结果表明涂层具有致密的层状结构,扁平颗粒小,氧化物膜细小,硬质点相分布均匀,孔隙率低;在涂层中存在着多种结构复杂的组织和化合物相,包括单立方结构基体相FeAl、Fe3Al、AlNi,AlNi;硬质相Cr3C2、Fe3C及AlFe3C0.5;氧化物相FeO·Al2O3、Cr2O3、少量六方结构的α-Al2O3和面心立方结构的γ-Al2O3以及面心立方结构的FeO·Cr2O3;某些区域还存在面心立方结构的γ-(Fe,Ni).     

Y2O3改性石墨/CaF2/TiC/镍基合金复合涂层微观组织与摩擦学性能研究

为提高石墨/CaF₂/TiC/镍基合金（GCTN）复合涂层的力学性能和摩擦学性能,运用等离子喷涂技术在45钢表面制备了Y₂O₃改性GCTN复合涂层,研究了Y₂O₃对复合涂层的微观组织、显微硬度、断裂韧性和摩擦磨损性能的影响。结果表明：Y₂O₃改性GCTN复合涂层主要由γ-Ni、CrB、Cr7C₃、TiC、CaF₂和石墨等物相组成。Y₂O₃在等离子火焰加热作用下与C元素反应生成活性元素Y,Y净化了复合涂层的微观组织,并细化了CrB、Cr₃C7等硬质相晶粒,提高了其致密性。当Y₂O₃质量分数为0.5%时,复合涂层的显微硬度和断裂韧性分别为593.3MPa和6.82MPa·m^1/2,比不含Y₂O₃的复合涂层分别增大了8%和22%,其机理主要是Y₂O₃细化了CrB、Cr₃C₇等硬质相晶粒,起到了细化强化作用。由于GCTN-0.5Y₂O₃复合涂层的显微硬度和断裂韧性显著提高,减少了其黏着磨损和微观断裂磨损,因而GCTN-0.5Y₂O₃复合涂层的摩擦因数和磨损率最小,分别为0.085和0.39×10-3mm3/m。     

镍含量对等离子喷涂Ni-Cr2O3复合涂层耐蚀性能的影响

将质量分数为5%,10%,15%,20%的镍粉加到纯Cr2O3陶瓷粉中,采用等离子喷涂技术在20钢表面制备了Ni-Cr2O3复合涂层;通过X射线衍射、显微组织分析、电化学试验、盐雾试验等方法研究了镍含量对复合涂层相组成、组织形貌以及耐蚀性能的影响。结果表明:复合涂层为层状结构;随着镍含量的增多,涂层物相未发生改变,复合涂层的耐蚀性先升后降,且镍质量分数为15%的复合涂层耐蚀性能最好。     

陶瓷增强相对金属-陶瓷复合涂层的影响

对电弧喷涂几种不同陶瓷增强相的Fe复合涂层的特点和性能进行了研究，在20钢基体上喷涂含陶瓷TiB2／Al2O3，TiB2-Cr3C2，TiB2，Cr3C2及TiB2-Cr3C2-Al2O3的管状喷涂丝材，采用光学显微镜和XRD对涂层的微观特性进行分析，结果表明，涂层中含有TiB2，Al2O3，Cr3C2，Cr3O2等陶瓷相。通过对涂层常规性能测试表明，含TiB2／Al2O3和Cr3C2的涂层孔隙率较低、结合强度高、并具有优良的耐磨性及抗热震性能。     

Y2O3纳米颗粒对电镀Ni-W涂层组织结构和电化学腐蚀性能的影响

在添加不同含量Y2O3纳米颗粒(质量浓度分别为0,5,10,20g·L-1)的电镀溶液中沉积Ni-W合金涂层,研究了Y2O3纳米颗粒的加入对涂层显微组织、微观形貌和电化学腐蚀性能的影响.结果表明:Y2O3纳米颗粒的添加减少了涂层表面结节状结构,细化了涂层晶粒,增大了微观应变;当Y2O3纳米颗粒的质量浓度在5～10 g·L-1时,所得涂层的表面粗糙度小于未添加纳米颗粒涂层的,但当质量浓度增至20 g·L-1时,表面粗糙度高于未添加纳米颗粒涂层的;Y2O3纳米颗粒的添加提高了涂层的耐电化学腐蚀性能,并且当Y2O3纳米颗粒的质量浓度为10 g·L-1时,涂层的耐电化学腐蚀性能最优.     

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。     

溶胶—凝胶工艺制备Al2O3-ZrO2涂层对工程陶瓷表面改性的研究

采用溶胶—凝胶工艺在SG4氧化铝基工程陶瓷上成功制备了Al2O3-ZrO2涂层。利用差热分析(DTA)、扫描电子显微镜(SEM)、X射线衍射(XRD)等分析手段对Al2O3-ZrO2涂层的物相组成、表面和断面形貌进行了表征。分别对精磨、热处理、Al2O3-ZrO2涂层试样的抗弯强度和Weibull模数进行了比较。结果表明Al2O3-ZrO2涂层可明显改善工程陶瓷的表面质量；涂层与基体结合紧密，无明显界面层；涂层试样的抗弯强度和Weibull模数均比未涂层试样显著提高。     

添加CeO2对超音速火焰喷涂微纳米结构WC-10Co4Cr涂层组织和性能的影响

采用超音速火焰(HVOF)喷涂技术制备了微纳米结构WC-10Co4Cr涂层和质量分数1%CeO₂改性微纳米结构WC-10Co4Cr涂层,研究了CeO₂的添加对涂层显微组织、力学性能和耐磨粒磨损性能的影响。结果表明：CeO₂的添加对粉末烧结过程中Co₃W₃C相的形成有抑制作用,同时能够减少喷涂过程中W₂C相的生成;CeO₂改性涂层的孔隙率为未改性涂层的72%;CeO₂的添加会加剧涂层的铬元素聚集程度,不利于CoCr黏结相的生成;CeO₂改性涂层的力学性能和耐磨粒磨损性能均低于未改性涂层,显微硬度和断裂韧度分别降低了11%和7%,经过15 600 r磨损后,其磨损质量损失率比未改性涂层高36%。     

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。     

Tribological properties of ZrO2 (Y2O3)-Mo-BaF2/CaF2 composites at high temperatures

ZrO₂ (Y₂O₃) with different contents of BaF₂/CaF₂ and Mo were fabricated by hot pressed sintering, and the tribological behavior of the composites against SiC ceramic was investigated from room temperature to 1000 °C. It was found that the ZrO₂ (Y₂O₃)-5BaF₂/CaF₂-10Mo composite possessed excellent self-lubricating and anti-wear properties. The low friction and wear were attributed to enhanced matrix and BaMoO₄ formed on the worn surfaces.     

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.     

单层MoS2和WS2的太赫兹近场显微成像研究

采用太赫兹散射式扫描近场光学显微镜(THz s-SNOM)研究了化学气相沉积法制备的单层MoS₂和WS₂晶粒的太赫兹近场响应。在没有可见光激发时,未探测到可分辨的太赫兹近场响应,说明晶粒具有较低的掺杂载流子浓度。有可见光激发时,由于光生载流子的太赫兹近场响应,能够测得与晶粒轮廓完全吻合的太赫兹近场显微图。在相同的光激发条件下,MoS₂的太赫兹近场响应强于WS₂,反映了两者之间载流子浓度或迁移率的差异。研究结果表明,THz s-SNOM兼具超高的空间分辨率和对光生载流子的灵敏探测能力,对二维半导体材料和器件光电特性的微观机理研究具有独特的优势。     

Tribological properties of spark-plasma-sintered ZrO2(Y2O3)-CaF2-Ag composites at elevated temperatures

Spark-plasma sintering is employed to synthesize self-lubricating ZrO₂(Y₂O₃) matrix composites with different additives of CaF₂ and Ag as solid lubricants by tailoring the composition and by adjusting the sintering temperature. The friction and wear behavior of ZrO₂(Y₂O₃) matrix composites have been investigated in dry sliding against an alumina ball from room temperature to 800 °C. The effective self-lubrication at different temperatures depends mainly on the content of various solid lubricants in the composites. The addition of 35 wt.% Ag and 30 wt.% CaF₂ in the ZrO₂(Y₂O₃) matrix can promote the formation of a well-covered lubricating film, and effectively reduce the friction and wear over the entire temperature range studied. The friction coefficients at low temperatures were at a minimum value for the composite containing 35 wt.% of silver. At this silver concentration, low and intermediate temperature lubricating properties are greatly improved without affecting high-temperature lubrication by the calcium fluoride in ZrO₂(Y₂O₃) matrix composites. The worn surfaces and transfer films formed during wear process have been characterized to identify the synergistic lubrication behavior of CaF₂ and Ag lubricants at different temperatures.     

表面活性剂含量对氧化铈/氧化硅复合磨料分散性的影响

以乙醇为溶剂及表面活性剂,以氨水为催化剂,利用正硅酸乙酯的水解得到氧化硅颗粒,并分析乙醇质量92%时制备的氧化硅颗粒呈球形,粒径分布均匀,表面光滑,呈单分散状态;乙醇质量分数为96%时制备的氧化硅颗粒粒径分布范围大,并且小颗粒团聚一体,聚集到大颗粒上.基于理想的氧化硅颗粒,利用化学沉淀法制备CeO2/SiO2复合磨料,并通过透射电子显微镜(TEM)及X射线衍射仪(XRD)对制备的样品进行表征.结果表明,制备的CeO 2/SiO2复合磨料为球形,粒径为150分数对制备的氧化硅颗粒以及氧化铈/氧化硅复合磨料分散性的影响.结果表明:水解体系中乙醇质量分数为71%时制备的氧化硅颗粒基本呈球形,粒径分布范围大,呈少量单分散状态;乙醇质量分数为~250 n m ,具有草莓状核壳的包覆结构,作为抛光磨料可以提高抛光表面质量.     

Wear properties of two-phase Al2O3/ZrO2 (Y2O3) ceramics at temperatures from 296 to 1073 K

Reciprocating sliding friction experiments were conducted with various two-phase, directionally solidified Al₂O₃/ZrO₂ (Y₂O₃) pins sliding on B₄C flats in air at temperatures of 296, 873, and 1073 K under dry sliding conditions. Results indicate that all the Al₂O₃/ZrO₂ (Y₂O₃) ceramics, from highly Al₂O₃-rich to ZrO₂-rich, exceed the main wear criterion requirement of 10⁻⁶ mm³ N⁻¹ m⁻¹ or lower for effective wear-resistant applications. Particularly, the eutectics and Al₂O₃-rich ceramics showed superior wear properties. The composition and microstructure of Al₂O₃/ZrO₂ (Y₂O₃) ceramics played a dominant role in controlling the wear and friction properties. The controlling mechanism of the ceramic wear, friction, and hardness was an intrinsic effect involving the resistance to shear fracture of heterophase bonding and cohesive bonding and the interlocking microstructures at different scales in the ceramics.     

钙硼硅系LTCC生瓷带在收/发组件中的应用

低温共烧陶瓷(LTCC)技术是实现机载、星载、舰载相控阵雷达收/发组件小型化、轻量化、高性能、高可靠的有效手段。由于技术落后,国内缺少商品化的微波LTCC材料,严重制约了LTCC技术的发展。文中对国产钙硼硅系LTCC生瓷带在X波段收/发组件中的应用进行了深入研究,分析了钙硼硅系LTCC生瓷带的工艺性能、浆料匹配性能以及微波性能,并采用国产钙硼硅系LTCC生瓷带研制了X波段收/发组件,性能指标满足相控阵雷达技术要求,为微波LTCC材料的国产化进行了有益的探索。     

Al2O3-TiB2-ZrO2三元复合陶瓷刀具的性能研究

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二氧化硅微球颗粒的解团聚研究

二氧化硅微球颗粒在无水和水相介质中都极易发生自组装现象,进而严重影响该颗粒的特性研究。为了更好地使用和研究二氧化硅微球颗粒,需要进行解团聚工艺研究。实验研究了不同尺度的颗粒的团聚特性和现象,提出了一种工艺,该工艺方法可以很好地实现大团聚的二氧化硅微球颗粒的解团聚。经过尼康显微镜观察,显示该工艺不仅很好地完成了二氧化硅微球的解团聚,而且提高了颗粒的分散性和稳定性。