Tribological Behavior of Nano-ZrO2 Reinforced PTFE-PPS Composites

Polytetrafluoroethylene (PTFE) is a commonly used seal material for oil-free engine that is well known for its excellent tribological properties. In this work, the nano-ZrO2 particles were used as the friction modifiers to improve the friction and wear performance of PTFE-PPS composites. The friction and wear characteristics of PTFE/PPS-nano-ZrO2 composites were investigated by a block-on-ring tester under dry friction sliding condition. The worn surfaces, counterpart transfer films and wear debris were studied by scanning electron microscopy and X-ray photoelectron spectroscopy. It was found that the increase of nano- ZrO2 content could effectively reduce the coefficient of friction and enhance the anti-wear ability of PTFEPPS composites. Especially, the best tribological properties of the composites were obtained when the particle content of nano-ZrO2 was 10 vol%, the anti-wear performance of composite is 195 times better than that of the unfilled PTFE-PPS composite. Under different conditions, the coefficient of friction of PTFE/PPS-nano-ZrO2 composites was more affected by the applied load while the wear rate was more affected by the sliding velocity.

Tribological Behaviours of PTFE Composites Filled with PEEK and Nano-ZrO2 Based on Pin-on-Flat Reciprocating Friction Model

Nano-ZrO2 and PEEK particles were synergistically filled in unfilled PTFE to improve the wear resistance and maintain a relatively low friction coefficient,and the materials were studied using a reciprocating sliding friction and wear tester.In the friction tests,the evolution of various tribological characteristics in both the contact interfaces and debris was observed,and the wear mechanism of the PTFE composites was investigated.The results showed that the wear rate of the PTFE composites synergistically filled with nano-ZrO2 and PEEK was lower and its friction coefficient was slightly higher than that of the unfilled PTFE;the uniformity and continuity of the transfer film generated by the composite with nano-ZrO2 and PEEK were the best,and the particle size of the debris was minimal in comparison to that in other sample systems.

Investigation of N-（Hydroxylethyl）pyrrolidone Dehydration over REOx-doped Nano-ZrO2 Catalyst

Catalyst plays an important role in the dehydration of N-（hydroxylethyl）pyrrolidone （NHP） to prepare N-vinyl-pyrrolidone （NVP）. At present, NVP yield is only about 30% on commercial ZrO2 catalyst. A coupled precipitation and solid dispersion technique was designed to prepare the nano-ZrO2 catalyst, in which rare earth metal oxides （REOx） was used as electronic promoter. The results indicated that the catalyst doped REOx （S-1.0） exhibits the optimum performance of NHP dehydration at moderate conditions. NHP conversion and NVP selectivity are respectively 97.0%, 82.3%. Of special interest is that the indexes of the catalyst （S-1.0-1.0） are up to 98.4% and 89.2% respectively. Furthermore, this catalyst bears the good stability. It means that nano-ZrO2 doped REOx catalyst might be a potential commercial catalyst for the NHP dehydration.

火焰喷涂PA1010/nano-ZrO_2复合涂层的非等温结晶动力学

利用火焰喷涂法制备了聚酰胺1010(PA1010)/纳米氧化锆(nano-ZrO2)复合涂层。采用示差扫描量热法(DSC)研究其非等温结晶行为,对所得的数据分别用Jeziorny法、Ozawa法和Mo法进行处理。结果表明,用Jeziorny法和Mo法处理非等温结晶过程比较理想,而Ozawa法不适用。用Jeziorny法求出的参数Zc(结晶速率常数)和n(Avrami指数)均随降温速率的增加而增加;nano-ZrO2的加入使复合涂层的Zc和n略大于纯PA1010涂层;并使复合涂层结晶半衰期降低、结晶速率及结晶度增大。表明nano-ZrO2具有明显的成核剂作用,加快PA1010的结晶速率,提高涂层的结晶度。

Effect of Nano-ZrO_2 on Microstructure and Thermal Shock Behaviour of Al_2O_3/SiC Composite Ceramics Used in Solar Thermal Power

The Al2O3-ZrO2（3Y）-SiC composite ceramics used in solar thermal power were prepared by micrometric Al2O3,nano-ZrO2 and SiC powders under the condition of pressureless sintering.The bulk density and bending strength of samples with 10vol% nano-ZrO2 sintered at 1480℃ were 3.222 g/cm3 and 160.4MPa,respectively.The bending strength of samples after 7 times thermal shock tests （quenching from 1000℃ to 25℃ in air medium） is 132.0MPa,loss rate of bending strength is only 17%.The effect of nano-ZrO2 content on the microstructure and performance of Al2O3-ZrO2（3Y）-SiC composite ceramic was investigated.The experimental results show that the bending strength of samples with above 10vol% nano-ZrO2 content has decreased,because the volume expansion resulting from t-ZrO2 to m-ZrO2 phase transformation is excessive;Adding proper nano-ZrO2 would be contributed to improve the thermal shock resistance of the composite ceramics.The Al2O3-ZrO2（3Y）-SiC composite ceramic has promising potential application in solar thermal power.

Synthesis and Characterization of Aluminum Doped Nano-ZrO_2 by Surfactant-assisted Route

Recently, more and more interest has been focused on zirconia and its characteristics. In this paper, aluminum can be successfully incorporated into nano-ZrO2 via a cationic surfactant assisted route in the earlier preparation procedure. XRD, TEM, EDS, Uv-vis and N2 adsorption-desorption analysis methods were adopted for the characterization of prepared samples. The results show that aluminum has been homogeneously incorporated into nano-ZrO2. The prepared aluminum-doped samples show a distinctive blue shift in the Uv-vis spectra compared to normal nano-ZrO2. The distinctive increase of thermal stability and a mesoporous structure were observed.

KH-151硅烷改性纳米ZrO_(2)对铝合金表面环氧树脂涂层防护性能的影响

在6061铝合金表面制备了硅烷改性纳米ZrO_(2)环氧树脂涂层,采用电化学测试和腐蚀试验,研究了纳米ZrO_(2)添加量对硅烷改性纳米ZrO_(2)环氧树脂涂层防护性能的影响,并对比了不同转化处理工艺下涂层的物理性能和防护性能。结果表明:当纳米ZrO_(2)添加量为100 mg/L时,硅烷改性纳米ZrO_(2)环氧树脂涂层试样的极化电阻为2 719Ω·cm^(2)、自腐蚀电流密度为2.528×10^(-6) A·cm^(-2);在经不同转化处理工艺处理的涂层中,硅烷改性纳米ZrO_(2)环氧树脂涂层的平均厚度为55μm,涂层剥离面积比例为5%,附着力达到1级,极化电阻最大,自腐蚀电流密度最小,涂层防护性能最佳。

Pre-PET Graft Modification of Nano-ZrO_2 and Its Effect on Mechanical Property of PC Composites

Nano-ZrO2 particles were modified by poly(ethylene terephalate) prepolymer(pre-PET) via polycondensation.FT-IR,TEM,and TGA results showed that pre-PET was successfully grafted on the surface of nano-ZrO2particles.Compared to the original nano-ZrO2,the grafted nano-ZrO2 had better compatibility with the polycarbonate(PC) matrix and could be dispersed more homogeneously in PC.Hence,interfacial adhesion between ZrO2 and PC was enhanced.The mechanical properties of the resultant PC/nano-ZrO2 composite like tensile strength and notched impact strength were greatly improved.Calculated respectively from tensile yield stress PC/nano-ZrO2 composites,the interfacial interaction parameter B was employed to quantitatively characterize the effective interfacial interaction between the nano-ZrO2 and PC matrix.

MF/纳米ZrO_2增韧氧化铝陶瓷复合材料的力学性能

选用莫来石纤维(MF)和纳米ZrO2为增强体制备了MZTA复合增韧氧化铝陶瓷复合材料。通过设计正交试验讨论了MF含量、nano-ZrO2含量、烧结温度、保温时间等因素对材料力学性能的影响,利用扫描电镜、能谱分析仪研究了陶瓷复合材料的微观结构与性能的关系。结果表明:当莫来石纤维和纳米ZrO2的质量分数分别为10%,烧结温度为1550℃,保温时间为30 min,陶瓷复合材料的抗弯强度、断裂韧性分别达到712 MPa、10.05 MPa.m1/2,与纯Al2O3陶瓷相比晶粒细化、力学性能显著提高;纤维的拔出、桥联、裂纹扩展路径偏转、沿晶断裂等消耗了大量的断裂能、缓和了裂纹尖端的应力是材料断裂韧性提高的主要原因。

纳米ZrO_2在复合镀中的应用

对纳米ZrO2粉末在制备复合镀层中的应用及改善镀层性能的机理,包括制备高硬度、高耐磨、高温抗氧化、耐腐蚀和具有电化学活性等功能的复合镀层的最新进展以及纳米颗粒在改善镀层耐腐蚀性和增强镀层硬度等方面的可能机理,主要包括超细晶强化、硬质点弥散强化和高密度位错强化等进行了介绍。

液相法制备纳米ZrO_2粉体的热处理

用改进的液相法在不同热处理工艺下制备了纳米ZrO2粉体. 样品的TEM,SAXS,BET和XRD分析结果表明, 热处理对纳米ZrO2粉体性能的影响是显著的. 结合实验与理论分析, 得出粉末颗粒长大、团聚的机制与热处理对成份、粒度及微观结构变化均有影响.

纳米ZrO_2改性热塑性聚酰亚胺复合材料的摩擦磨损性能

采用热模压工艺制备了纳米ZrO2改性热塑性聚酰亚胺(PI)纳米复合材料,考察了复合材料的力学性能、在干摩擦和油润滑条件下的摩擦磨损性能,并利用扫描电子显微镜观察了冲击断面和磨损表面形貌。结果表明:纳米ZrO2在低含量下对PI复合材料的力学性能影响不大,随着其含量的增大,材料的弯曲性能下降,刚性增大。在干摩擦条件下,较低的纳米颗粒含量有助于转移膜的形成,从而降低材料的摩擦因数及磨损率。纳米ZrO2体积分数为1%时,材料的摩擦磨损性能较纯PI分别下降了50%和15%;在油润滑条件下,润滑油的流动性有助于纳米颗粒分布到整个摩擦界面,PI复合材料的摩擦因数及磨损率有明显降低,此时磨损机制以疲劳磨损为主。

水性纳米ZrO_2/环氧聚硅氧烷杂化防腐涂层的制备与性能

采用水性纳米ZrO_2溶胶与γ-缩水甘油醚氧丙基三甲氧基硅烷(GPTMS)为原料,通过溶胶-凝胶方法,制备了水性有机无机杂化防腐涂层。实验研究了ZrO_2/GPTMS摩尔比对涂层耐盐雾性能及电化学性能的影响。实验结果表明,涂层的耐腐蚀性能随着摩尔比的增加呈现先增强后下降的趋势,其中1∶5涂层的耐腐蚀性能最强,耐盐雾时间达到1 500h,是未涂覆涂层样板耐盐雾时间的20倍左右,电化学交流阻抗为107Ω·cm2,腐蚀电流密度为5.84×10-10 A/cm2。从1∶5涂层的SEM照片发现,涂层中纳米ZrO_2粒子分散均匀,无团聚现象。另外,TG分析表明,涂层的热稳定性能随着摩尔比的增大而增加。

纳米ZrO_2/Pt复合材料的高温性能及高温断口分析

用胶体共混法制备纳米ZrO2/Pt粉体,再通过粉末冶金的方法制备出纳米ZrO2/Pt复合材料。通过正交试验方法对各影响条件进行了优选,测试了在最佳条件下制备的纳米ZrO2/Pt复合材料的高温性能,并对其高温拉伸断口及高温蠕变断口进行了分析。

纳米ZnO对纳米ZrO_2(8Y)致密特性及电导率影响研究

采用纳米ZrO2(8Y)粉和纳米ZnO粉为原料,对掺少量ZnO的ZrO2(8Y)进行无压烧结研究.实验结果表明,掺少量的ZnO能促进ZrO2与Y2O3的反应,加快四方相向立方相的转变,样品致密度和电导率显著提高.掺0.5wt％ZnO样品在1200℃煅烧2h的陶瓷致密度为94％,700℃时的电导率为9.02×10-3cm-1·Ω-1.

纳米ZrO2和聚醚醚酮填充聚四氟乙烯的摩擦学性能基于环-块摩擦模型的演变过程

用不同体积分数的纳米ZrO2和聚醚醚酮(PEEK)颗粒填充改性聚四氟乙烯(PTFE)复合材料。使用环-块摩擦磨损试验机测试PTFE复合材料在滑动速度为2 m/s、载荷为200 N的试验条件下的摩擦学性能。获取不同阶段摩擦学性能的数据,计算出在整个试验过程中样品的瞬时磨损率。利用扫描电镜观察不同试验阶段对偶钢环表面形貌的变化图像并进行分析。利用仿真模拟软件(ABAQUS)对摩擦过程中PTFE复合材料的接触应力变化进行分析。结果表明,纳米ZrO2和PEEK颗粒可以协同改善PTFE复合材料的摩擦学性能。特别是添加8%的纳米ZrO2和20%的PEEK能使PTFE复合材料同时获得最佳的耐磨性(1.29×10-6 mm3/Nm)和较低的摩擦系数。在摩擦试验的后期PTFE复合材料的瞬时磨损率突然急剧上升。根据瞬时磨损率、磨损表面、转移膜形貌和磨屑形态特征的变化规律,将整个磨损过程分为3个阶段(低磨损阶段、过渡磨损阶段和严重磨损阶段)。

纳米ZrO2对热喷涂尼龙1010涂层非等温结晶与熔融行为的影响

利用火焰喷涂法制备了尼龙1010(PA1010)/n-ZrO2复合涂层,采用差示扫描量热法(DSC)对复合涂层的非等温结晶过程、熔融行为进行了分析。结果表明,纳米ZrO2粒子的加入不仅能提高复合涂层的结晶速率和结晶温度,而且使复合涂层的熔融峰肩峰的熔融温度高于纯PA1010涂层。结论:纳米ZrO2粒子具有成核剂的作用,诱导尼龙大分子结晶,使其结晶能力及结晶的完善程度提高。

不同分散方法对纳米ZrO_2/PMMA复合材料挠曲强度的影响

目的:研究不同分散方法对氧化锆(ZrO2)纳米填料/聚甲基丙烯酸甲酯(PMMA)复合材料试件挠曲强度的影响。方法:在丙酮溶液中用硅烷偶联剂Z-6030对纳米ZrO2颗粒进行表面修饰,将经过表面修饰后的纳米ZrO2颗粒按照3%的添加量加入到义齿基托树脂Ⅱ型粉剂中,然后分别采用手工、球磨和超声湿混3种方法予以分散混合,并以不添加纳米ZrO2颗粒的PMMA作为空白对照组,再与II型液剂反应后制成4组标准试件,最后进行三点弯曲测试。实验数据采用SAS6.12软件包进行单因素方差分析,均数间进行两两比较(Newman-Keuls检验)。结果:复合材料的挠曲强度以球磨组最高,达73.64MPa,手工混合组最低,为62.86MPa。球磨、超声2组的挠曲强度显著高于手工组和空白对照组(P<0.05)。球磨和超声2组之间无显著差异(P>0.05)。结论:以球磨、超声2种方法混合纳米ZrO2颗粒和PMMAII型粉剂,可得到较好的分散效果,从而提高复合树脂的挠曲强度。

高速电喷镀纳米ZrO_2/Ni复合层组织及高温氧化性能

通过高速电喷镀工艺在Ni基高温合金K17表面沉积了纳米ZrO2/Ni复合镀层,测定了K17合金和纳米ZrO2/Ni复合镀层在1000℃的氧化动力学曲线,采用SEM、XRD和显微硬度计分析了纳米ZrO2/Ni复合镀层的组织结构、表面形貌和表面显微硬度;实验结果表明,镀层中纳米ZrO2的存在有利于细化复合镀层晶粒,提高复合镀层显微硬度;1000℃氧化5h后,纳米ZrO2/Ni复合镀层氧化膜由NiO,ZrO2和Cr2O3组成,1000℃氧化100h后,纳米ZrO2/Ni复合镀层氧化膜由NiO,NiCr2O4,ZrO2and Cr2O3组成;纳米ZrO2/Ni复合镀层中ZrO2和Cr2O3的存在明显改善了K17合金的抗高温氧化性。

ZrO_2/TiO_2/PVDF超滤膜的制备与性能研究

为改善聚偏氟乙烯(PVDF)超滤膜亲水性的不足,试验采用相转换法掺杂共混制备了含不同质量配比的纳米二氧化锆(ZrO2)粒子和纳米二氧化钛(TiO2)粒子的PVDF杂化膜,利用扫描电子显微镜(SEM)、接触角测量仪、傅里叶红外光谱仪(FT-IR)、X射线衍射仪(XRD)和热重分析仪对PVDF纯膜和PVDF杂化膜的结构和性能进行了表征及测试,并考察了两种无机纳米粒子添加量及添加比例对PVDF杂化膜膜通量的影响。结果表明:当添加纳米粒子的总质量分数为1%、且ZrO2与TiO2两种纳米粒子的质量比为1∶1时,PVDF杂化膜的膜通量是PVDF纯膜的1.43倍;纳米粒子的加入改善了PVDF膜的亲水性,且在一定程度上提高了PVDF膜的热稳定性。