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.

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.

超细粉体在液相中分散稳定性的研究

文章以纳米 Zr O2 的水悬浮液为例 ,通过粒度分布测量法和上层清液的光透过法等方法 ,研究水溶液中 Zr O2 粉体的表面特性、聚电解质分散剂的结构与数量以及悬浮液的离子浓度等对悬浮液稳定性的影响 ,提出了改善纳米 Zr O2 在水溶液中分散稳定性的几点措施。研究结果表明 ,分散剂的用量及 p H值是控制粉体悬浮液分散性和稳定性的主要参数 ,研究结果较满意。

ZrO_2—Al_2O_3复相陶瓷的研究

以纳米ZrO 、微米Al O 为原料,采用无压烧结方式制备了ZTA 复相陶瓷。结果表明:nano-ZrO 的 2 2 3 2加入有利于制备细晶ZTA 复相陶瓷。此外,nano-ZrO 的加入对 Al O 陶瓷的显微结构也产生影响,ZrO 颗粒以 2 2 3 2“晶内型”和晶界型两种形式存在。合理的配方组成及制备工艺有利于 Z r O 以四方亚稳相存在。Z r O 含量为 2 23 0 w t % 时,其四方相含量可达 6 9 %,有利于应力诱导相变增韧,该 Z T A 复相陶瓷的抗弯强度、断裂韧性分别达到 604MPa、6.87MPa·m1/2。

纳米ZrO_2粉体的热处理研究

用共沉淀法在不同热处理工艺下制备纳米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分。

均匀设计在沉淀法制备纳米二氧化锆中的应用

用氨水作沉淀剂与氯氧化锆进行反应生成的胶体沉淀再焙烧制备出纳米二氧化锆。利用均匀设计考察了反应物量比、反应物浓度、焙烧温度和焙烧时间对产品平均粒径、分散性和晶形状态的影响。粒径由TEM测出 ,分散性和晶形状态由人为评分给出。研究表明反应物量比、氯氧化锆浓度和焙烧温度对产品性质影响较大。本实验优化的制备条件是 :n(氨水 )∶n(氯氧化锆 ) =3∶1;c(氯氧化锆 ) =0 .1mol/L ;c(氨水 ) =0 .5mol/L ;焙烧温度为 6 0 0℃ ;焙烧时间为 1h ,在此条件下可获得均匀分散的纳米二氧化锆 ,收率为 95 .4%。XRD分析结果表明 。

液相烧结对微-纳复合ZTA陶瓷组织性能的影响

在微 纳复合ZTA材料中加入少量复合助剂 ,材料在较低温度下实现液相烧结 ,促进了材料的致密化过程 ,提高了材料的相对密度。ZTA陶瓷发生液相烧结后 ,ZrO2 在晶界处所形成的熔与未熔共存的独特微观结构使之在基体晶界上分布更加均匀 ,晶界结合较为紧密 ,钉扎作用增强 ,材料得到了强韧化。由于ZrO2 与Al2 O3 的弹性模量不匹配 ,在粒子周围形成的切应力使扩展裂纹遇到未溶粒子易发生偏折 ,造成部分的穿晶断裂 ,使材料的断裂模式发生改变。并且这种结构更加有利于应力诱导相变 。

反相胶束法制备纳米ZrO_2粉体

利用NA/煤油—n C6 OH/NH3 ·H2 O反胶束体系 ,制备了纳米ZrO2 粉体。采用TG DTA、TEM、XRD等手段对粉体及前驱体进行表征 :粉体粒度分布均匀 ,无硬团聚 ,平均粒度为2 0～ 40nm。并且研究了反相胶束中的溶水量对ZrO2 粒径的影响以及 pH值对ZrO2 晶型的影响。并推测 2 0～ 40nmZrO2 的单斜晶 (m)与四方晶 (t)可能的相转变温度为 72 3℃ ,比相应的体相材料降低了近 45 0℃。

纳米ZrO_2粉体表面的特种光谱研究

用共沉淀法制备了两个系列的纳米ZrO2 粉体 ,用活性剂DuramaxTMD - 30 2 1进行了表面处理。采用SAXS分析了样品的晶粒度 ,对比分析了样品的红外与拉曼光谱。分析结果表明 ,改性前后纳米ZrO2

水热法制备ZrO_2纳米微晶及对乙醇和丁烷气敏性研究

用水热法制备 Zr O2 纳米微晶的平均尺寸为直径 5 nm,长 7.5 nm。由 X射线衍射确认晶相为单斜相。并对其形状和大小进行了透射电镜和激光散射分析 ,结果表明 Zr O2 纳米粒子在水溶液中存在软团聚 ,团聚体平均尺寸约 90 nm。着重研究了 Zr O2 纳米微晶对乙醇及丁烷的气敏性能 ,结果表明用纳米级 Zr O2 粒子制备的气敏元件对乙醇和丁烷有好的气敏性。并且随着纳米粒子尺寸降低 。

纳米(ZnO,Al_2O_3)复合掺杂对3Y_2O_3-ZrO_2材料电性能的影响

以 3Y2 O3-ZrO2 纳米粉和ZnO ,Al2 O3纳米粉为原料 ,采用交流阻抗谱技术对掺少量ZnO和Al2 O3的 3Y2 O3-ZrO2 烧结陶瓷进行电性能研究。研究表明 :少量纳米ZnO掺杂降低了 3Y2 O3-ZrO2 的电导率 ,但随着掺入量的增加 ,电导率开始回升。在ZnO掺杂样品中加入少量纳米Al2 O3进行复合第二相掺杂 ,结果提高了3Y2 O3-ZrO2 材料的电导率。同时少量Al2 O3的掺入降低了晶粒电导活化能 。

纳米/微米Al_2O_3-ZrO_2内衬复相陶瓷的自蔓延高温合成

采用SHS重力分离技术制备出内衬Al2 O3 ZrO2 复相陶瓷。复相陶瓷基体主要由纤维状 (Al2 O3 +ZrO2 )共晶体组成 ,其中共晶体的ZrO2 纤维直径达到纳米 /微米尺度。经Vickers压痕法测试其断裂韧度为1 5 96MPa·m1 / 2 ,SEM观察和陶瓷材料断裂韧度测试得出裂纹的扩展主要受共晶体中Al2 O3 ZrO2 纳米 /微米相增韧机制控制 ,迫使裂纹沿共晶体边界或层片共晶体Al2 O3 ZrO2 相界偏转 。

纳米SiC颗粒对Al_2O_3基体中ZrO_2约束稳定的影响

采用热压的方法制备了纳米 Si C颗粒复合的 Al2 O3- Zr O2 陶瓷材料 ,研究了纳米 Si C颗粒对样品烧结性能以及对 Al2 O3基体中 Zr O2 约束稳定的影响。结果表明 ,纳米 Si C颗粒的加入影响样品的烧结性能。处于晶界的纳米 Si C颗粒降低了基体材料对 Zr O2 颗粒的约束 ,不利于四方相 Zr O2

SHS制备纳米/微米结构抗弹陶瓷可行性研究

针对用于现代装甲防护的高性能抗弹陶瓷 ,以SHS冶金技术 ,通过材料原位合成手段并在大过冷条件下熔体发生共生共晶反应 ,快速一次性制备出自燃自组装、具有 1 3复合晶内型结构的纳米 /微米结构Al2 O3 ZrO2 共晶复相陶瓷。Vickers压痕试验发现该陶瓷具有较高的断裂韧性并表现出较强的塑变行为 ,SEM观察发现该复相陶瓷的裂纹扩展路径主要受纳米 /微米结构 (Al2 O3 +ZrO2 )共晶结构所控制 ,影响该陶瓷韧化行为的主要因素在于以“内晶型”纳米相所构成的独特的增韧机制。试验预示着采用SHS冶金技术 ,通过控制Al2 O3 /ZrO2 复相陶瓷成分和凝固行为 (如采用离心冷却控制技术 ) ,可以制备出用于现代装甲防护的高性能、低成本、高可靠性新型抗弹复相陶瓷面板。

纳米Al_2O_3对纳米ZrO_2(4Y)常压烧结致密特性及电性能影响

采用纳米ZrO2 ( 4Y)粉和纳米Al2 O3粉为原料 ,对掺少量Al2 O3的ZrO2 ( 4Y)陶瓷进行无压烧结研究。实验结果表明 ,掺适量的Al2 O3可提高致密度 ,降低烧结温度。掺 1.0wt %纳米Al2 O3在 12 0 0℃煅烧 2小时的陶瓷致密度为 99.0 % ,烧结体晶粒长大略减缓。在纳米ZrO2 ( 4Y)中掺入少量的纳米Al2 O3可降低电导活化能 ,提高电导率。

Preparation of tetragonal CaO-ZrO_2 nano-powder by chemical coprecipitation method

With zirconium oxychloride, nitrate of lime and ammonia as raw materials, nano powder of CaO ZrO 2 was prepared by chemical coprecipitation method. By use of azeotropic distillation processing, chemical coprecipitation precursor was obtained. Phase transformation of the precursor was observed at the temperature of 593.81 ℃ and 1 234.56 ℃ respectively with DTA analyses. Phase structure was analyzed through XRD and Raman spectra. The average particle size of tetragonal zirconium oxide powder was 9.8 and 43.7 nm after calcination at 600 and 1 100 ℃ respectively which was tested by TEM and BET analyses. Furthermore, the influences of the doping of nitrate of lime and the average particle size of zirconium oxide on the stability of tetragonal zirconium oxide were also discussed.

纳米结构ZrO_2(Y)和ZrO_2(Y)-Al_2O_3粉体低温退火前后的结构和性质

研究等离子体 -化学方法制备的纳米结构 Zr O2 -Y2 O3 和 Zr O2 -Y2 O3-Al2 O3 粉体及其不同温度退火前后的结构、性质变化 .结果表明 ,用这种方法制备的粉体 ,烧结后具有很好的聚合性能 ,聚合结构可达到 1～ 2 μm,且内部晶粒尺寸很小 (2 5～ 35 nm) ;在 12 0 0℃以下退火 ,X射线衍射图谱上没有 Al2 O3 的衍射峰 ;对于两种体系 ,主相 Zr O2 的结构虽大致相同 ,但当低温退火 (<12 0 0℃ )时其在 Zr O2 -Y2 O3 体系中的晶格畸变比在 Zr O2 -Y2 O3-Al2 O3 系统中的变化更大 ;晶粒尺寸 (D)为 10～ 15

纳米ZrO_2陶瓷二维超声磨削温度影响因素分析

本文采用人工热电偶法,通过普通磨削和二维超声振动磨削的对比实验,回归分析了磨削深度、砂轮速度、工作台速度等磨削参数对纳米ZrO_2陶瓷磨削温度的影响。别外对纳米ZrO_2陶瓷这种非线性材料的磨削加工进行有限元仿真,比较实验测量数据与仿真结果,确定仿真分析对实际情况的指导作用。