SiO2/聚四氟乙烯复合薄膜的制备及力学性能

采用空气辅助干法共混、冷压烧结并车削成膜的方法制备了SiO₂填充量为35wt%、厚度为50 μm的聚四氟乙烯（PTFE）基复合薄膜。系统研究了SiO₂颗粒粒径对SiO₂/PTFE薄膜复合材料的孔洞缺陷和力学性能等的影响,并研究了SiO₂在PTFE中的分散情况及分子间相互作用对其性能变化的影响机制。结果表明,随SiO₂粒径的逐渐增大,其在PTFE中的分散趋于均匀,同时PTFE能更好地包覆粒子,因此SiO₂/PTFE薄膜孔洞缺陷逐渐减少,力学性能逐渐增强;当SiO₂的粒径D₅₀为12 μm时,其在PTFE中的分散均匀性最佳,SiO₂/PTFE复合薄膜孔洞缺陷最少,具有较好的力学性能,断裂伸长率达19.5%,拉伸强度达9.2 MPa。      

金属填充PTFE复合材料的摩擦磨损性能研究

利用ＭＨＫ－５００型环块磨损实验机,对金属Ｃｕ、ｐｂ及Ｎｉ填充改性的ＰＴＥＦＥ复合材料在干摩擦条件下与ＧＣｒ１５轴承钢对摩时的摩擦磨损性能进行了系统研究,并利用ＪＥＭ－１２００ＥＸ／Ｓ分析电子显微镜和光学显微镜对ＰＴＥＥ复合材料的磨屑及摩擦磨损表面进行了考察。摩擦磨损实验的结果表明,金属填料Ｃｕ、Ｐｂ及Ｎｉ大大改善了ＰＴＦＥ复合材料的耐磨性,ＰＴＦＥ复合材料的磨损量比纯ＰＴＦＥ降低了１－２个数量级     

Interface stress induced hardness enhancement and superelasticity in polytetrafluoroethylene/metal multilayer thin films

Polytetrafluoroethylene (PTFE)/Al, PTFE/Cu, and PTFE/Ti multilayer thin films have been deposited in order to investigate effects of interface energy on mechanical properties. PTFE, which has a low surface energy of 19.2 mJ/m², was used to introduce a large interface energy into multilayer thin films. PTFE thin film was deposited by rf magnetron sputtering using a PTFE sheet target. Al, Cu, and Ti were deposited by dc magnetron sputtering. The multilayer thin films were fabricated sequentially without breaking vacuum. Substrate used was aluminosilicate glass. The modulation period was changed from 6.7 to 200 nm. The total thickness was about 200 nm for all samples. The internal stress of metal layers changed from tensile to compressive and increased with decreasing modulation period for all of PTFE/Al, PTFE/Cu, and PTFE/Ti. Both hardness enhancement and superelasticity were observed in the results of nanoindentation measurements. The energy dissipated during nanoindentation process (one load and unload cycle) decreased with decreasing modulation period. The minimum value of the ratio of dissipated/loaded energy was < 40%, which is smaller than the values obtained for monolithic PTFE or metal films (about 73% for PTFE and 87% for Al, 72% for Cu, and 71% for Ti, respectively). This meant that the PTFE/metal nano-multilayer thin films became more elastic with decreasing modulation period. The tendency of change in the mechanical properties strongly correlated to internal stress. Mechanisms involved in anomalous behaviors in film hardness and elasticity were discussed based on the relationship to interface energy, interface stress, and internal stress, induced by multilayering of the films. It is concluded that a large compressive stress introduced in the thin films increased the energy needed to deform elastically or plastically the thin film during indentation, resulting in the increase in hardness and elasticity. The nanoindentation analysis of the multilayer thin films emphasized that in PTFE/metal multilayer thin films mechanical properties of the films depend on interface stress induced by the accumulated interface energy, being independent of bulk materials properties composing thin films, resulting in increase in hardness and elasticity.     

Thermoluminescent response of ZrO2 + PTFE prepared in Mexico to 90Sr/90Y beta particles

Results of studying the thermoluminescent response of undoped ZrO2 + PTFE pellets irradiated with 90Sr/90Y beta particles are presented. Previously, TL characteristics of ZrO2 films doped with rare earths were studied. Phosphor powder was obtained by evaporating a solution of zirconium nitrate in ethanol. In order to stabilise the traps in ZrO2 this phosphor was submitted to different thermal treatments. Optimal thermal treatment consisted in heating at 1100 degrees C for 24 h. With this powder. pressing at room temperature a mixture (2:1) of ZrO2 and polytetrafluoroethylene (PTFE), pellets of 5 mm diameter and 0.8 mm thickness were made. The glow curve of ZrO2 + PTFE pellets exhibited two peaks at 200 and 250 degrees C: its TL response as a function of beta particles dose was linear in the range from 2 to 60 Gy. Repeatability over 10 cycles was 1.8%. Fading at room temperature was 3.8% per month.     

聚丙烯腈填充聚四氟乙烯复合材料摩擦磨损性能研究EI

用机械共混、冷压成型和空气中烧结的方法制备了不同质量分数的聚丙烯腈填充聚四氟乙烯制品。用MM-200摩擦磨损试验机测试不同样品在干摩擦下的摩擦学行为;用扫描电子显微镜和光学显微镜对几种样品的磨损面、磨屑和转移膜进行观察和分析。结果表明,聚丙烯腈的加入,不但使聚四氟乙烯的磨损量大幅降低,而且还使其摩擦系数有所降低。通过扫描电子显微镜观察发现填充聚丙烯腈的聚四氟乙烯样品的对磨面有完整而且不易脱落的转移膜,这是其具有良好耐磨性的主要原因。     

双向拉伸PTFE微孔膜的制备及其孔性能

以聚四氟乙烯(PTFE)细粉料为原料通过一系列机械操作：推挤、滚压和拉伸制得双向拉伸微孔膜．膜的孔性能由GTL—D孔径测定仪和扫描电镜观察膜形态结构来测定．实验结果表明：PTFE粉料和拉伸条件影响相互联系的各项膜孔性能数据，而在不同机械操作阶段的膜形态结构又有显著的差别、双向拉伸微孔膜是呈孔径大小较均匀的纤维网状结构．     

Manufacturing Ternary Alloy NiBP-PTFE Composite Coatings by Dynamic Chemical Plating Process

The dynamic chemical plating technique is used to deposit NiBP coatings with incorporation of polytetrafluoroethylene (PTFE) particles. This technique is faster and simpler to perform compared to other electroless deposition techniques. Using a double nozzle gun, metal salt solution and reducing agents are sprayed to the surface, forming a deposit. Using scanning electron microscopy morphology of the coatings was studied. By dynamic chemical plating technique films with maximum incorporation rate of vol % 21 PTFE were deposited. Tribological studies were conducted by a ball/surface tribometer, at different applied loads (5, 15, 30, 45, 60 N). Deposited films exhibited interesting tribological properties with a friction coefficient of 0.3 for a film containing vol % 21 PTFE. The coating has a tendency to peel off locally at high applied loads. Friction coefficient increased with decreasing PTFE content.     

纳米TiO2与炭纤维协同填充PTFE复合材料的摩擦磨损性能

考察了不同含量的纳米二氧化钛对炭纤维/聚四氟乙烯复合材料摩擦磨损性能的影响,采用扫描电子显微镜、光学显微镜分析了磨损面、磨屑及对偶面转移膜形貌,并探讨了其磨损机理。结果表明,纳米TiO2与炭纤维能够很好地协同增强聚四氟乙烯,改变磨屑形成机理,有利于形成均匀致密的转移膜,明显提高CF/PTFE复合材料的耐磨性。当纳米TiO2含量为5%时,10?/PTFE复合材料表现出最佳的耐磨性,耐磨性又提高了2.77倍,而磨屑尺寸只有未加时的1/20。     

Structural and optical properties of ZnO thin films prepared by laser ablation using target of ZnO powder mixture with glue

ZnO thin films were deposited on ITO/glass substrates by pulsed laser deposition (PLD) using two different kinds of targets. One of the targets was made of pure ZnO powder and the other one consisted of a mixture of ZnO powder with cyanoacrylate glue. The structural and morphological properties of the films obtained using both targets were compared, in order to determine which one produces samples with properties more suitable for their use as buffer and antireflective layer in CdTe-based solar cells, also different heterostructures were deposited to study the optical properties of the obtained thin films and their utility in the applications mentioned before. The films deposited with the mixture powder target were polycrystalline with preferential orientations in the planes (100) and (101) with a high transmittance in the range of 70–90% in the 540–850 nm wavelength region and showed a high resistivity of \({\sim }1.30 \times 10^{2} \,\Omega \hbox { cm}^{-1}\), such properties are considered to be appropriate for thin films that are wanted to be used as a buffer and antireflective layer in CdTe solar cells.     

Formation of composite Cu–graphite and Cu–PTFE coatings and their tribological characterization

The Dynamic Chemical Plating (DCP) technique allows production of 2-μm copper films containing particles of graphite or PTFE in 18 and 15 min, respectively, at ambient temperature. DCP yields composites with particle-incorporation fractions of 12% for graphite micro-particles and 22% for PTFE nano-particles. The composite films show excellent tribological properties, acting as self-lubricating coatings with friction coefficients as low as 0.18.     

Composite NiB–Graphite and NiB–PTFE Surface Coatings Deposited by the Dynamic Chemical Plating Technique

Dynamic chemical plating (DCP) is an alternative for producing metallic deposits on nonconductive materials and can be considered as a modified electroless coating process. This article describes the formation of composite NiB–particle films by the DCP technique. The particles used were micrometric graphite (1–2 µm) or PTFE (50–500 nm). The conditions for production of these coatings are presented along with the deposition rates, surface morphology, friction properties, and the degree of particle incorporation into the films.     

The gas-sensing properties of thick film based on tetrapod-shaped ZnO nanopowders

Tetrapod-shaped ZnO nanopowders were prepared by the method of vapor-phase oxidation from metallic zinc as raw materials. The gas-sensing properties of thick film based on tetrapod-shaped ZnO nanopowders to volatile organic compounds (VOCs), benzene, toluene, xylene, alcohol and acetone were measured, and compared with that of commercial ZnO powders with granular shape. The results showed that tetrapod-shaped ZnO had the better gas-sensing properties: the maximum sensitivity temperature was reduced, the gas sensitivity was improved and the time of response–recovery was shortened. The differences in gas-sensing properties between the thick films were discussed in according to the morphological characteristics, size and agglomeration of raw powder as well as microstructure of sintered thick films.     

Hydrophobic properties of polytetrafluoroethylene thin films fabricated at various catalyzer temperatures through catalytic chemical vapor deposition using a tungsten catalyzer

Using the catalytic chemical vapor deposition (Cat-CVD) method, polytetrafluoroethylene (PTFE) thin films were fabricated on Si(100) substrates at various catalyzer temperatures, using a tungsten catalyzer, and Fourier transform infrared (FTIR) spectroscopy and X-ray photoemission spectroscopy (XPS) were used to confirm the fabrication of the films. An atomic-force microscope (AFM) and a scanning electron microscope (SEM) were employed to study the correlation between the wettability and surface morphology of the samples. It was found that the wettability of the PTFE thin films fabricated via Cat-CVD is strongly correlated with the sizes of the film surfaces' nanoprotrusions, and that superhydrophobic PTFE thin-film surfaces can be easily achieved by controlling the sizes of the nanoprotrusions through the catalyzer temperature. The comparison of the wettability values and surface morphologies of the films confirmed that nanoscale surface roughness enhances the hydrophobic properties of PTFE thin films. Further, the detailed analysis of the films' surface morphologies from their AFM images with the use of the Wenzel and Cassie models confirmed that the nanoscale surface roughness enhanced the hydrophobic property of the PTFE films. Further, the variations of the wettability of the PTFE thin films prepared via Cat-CVD are well explained by the Cassie model. It seems that the increase in the trapping air and the reduction of the liquid-solid contact area are responsible for the superhydrophobicity of the PTFE thin films prepared via Cat-CVD.     

Tribological behavior of PTFE nanocomposite films reinforced with carbon nanoparticles

Carbon-based nanoparticles synthesized by heat treatment of nanodiamond in the temperature range of 1000–1900 °C were added to PTFE film to investigate the structural effect of the carbon particles on the tribological properties of PTFE composite film. Carbon-based nanoparticles were prepared by milling with micron sized beads in chemically treated water before their addition to PTFE film. The wear and frictional properties of PTFE nanocomposite film were measured by the ball on plate type wear test. The wear resistance of PTFE film was found to be enhanced by the addition of 2 wt% of carbon nanoparticles. The wear coefficient of PTFE film was decreased from 16.2 to 3.5 × 10⁻⁶ mm³/N m by the addition of carbon-based nanoparticles heat-treated at 1000 °C. Increasing the heating temperature of the nanodiamonds caused the extent of aggregation and particle size to increase. The wear resistance of PTFE nanocomposite film was enhanced by the addition of nanodiamonds heat-treated at 1000 °C, but decreased when the heat treatment temperature of carbon nanoparticles was further increased. Tribological behavior of PTFE nanocomposite films depending on the types of carbon nanoparticles were explained based on the structural, physical and chemical modification of carbon nanoparticles.     

复配稀土改性剂对MGF/PTFE复合材料性能的影响

采用稀土改性剂(RES)与硅烷偶联剂(PTMS)按不同组分配比对磨碎玻璃纤维(MGF)表面进行改性处理,将改性后的磨碎玻璃纤维粉末与聚四氟乙烯分散液机械混合,然后热压制得复合材料。探讨了复配稀土改性剂对MGF/PTFE复合材料介电性能、热膨胀系数(CTE)、热导率的影响。采用FTIR手段对稀土改性剂未改性的磨碎玻璃纤维和改性后的磨碎玻璃纤维的结构进行了测试,并用扫描电子显微镜(SEM)对复合材料的断口形貌进行分析。结果表明,复配改性剂能很好地促进MGF与PTFE之间的界面粘结,提高MGF/PTFE复合材料的性能。当RES、PTMS的含量分别为0.3%(质量分数)、1.7%(质量分数)时,MGF/PTFE复合材料的性能最好。     

Mechanisms of increased wear resistance of composites based on PTFE doped with fullerene soot

We have studied the effect of small additives of a fullerene soot (FS) on the linear wear intensity I _h of poly(tetrafluoroethylele) (PTFE) in sliding friction on steel with water lubrication. The introduction of only 1% FS into PTFE leads to a sharp drop in I _h . The investigation of FS samples by means of small-and wide-angle X-ray scattering showed that FS contains C₆₀ fullerene and graphite nanocrystals with an average size of 20–25 nm and ultrafine carbon particles 2–3 nm in size. The presence of dispersed nanoscopic particles probably imparts the FS-doped PTFE samples the properties of nanocomposites. The possible mechanism of microcrack healing in PTFE by nanoparticles representing fullerene fragments is considered.     

Study of stress relaxation in polytetrafluoroethylene composites by cylindrical macroindentation

In the present work, the time-dependent mechanical behavior of three materials from the fluorocarbon family, including PTFE without filler, 15 vol.% regenerated graphite particles-filled PTFE, and 32 vol.% carbon and 3 vol.% graphite particles-filled PTFE, was investigated using cylindrical macroindentation. Indentation relaxation experiments with a cylindrical flat-tip indenter having a diameter of 1 mm were performed at three different strain levels. The generalized Maxwell model in terms of the Prony series and a time-dependent solution based on the power-law creep equation were used to model the viscoelastic response and to extract the time-dependent properties. The stress relaxation properties were found to improve with the addition of fillers. The unfilled PTFE exhibited the lowest stress–relaxation properties, whereas the 32 vol.% carbon and 3 vol.% graphite particles-filled PTFE composite showed the highest stress–relaxation properties.     

碳纤维增强聚醚醚酮复合材料滑动摩擦转移膜的ESCA研究

碳纤维增强聚醚醚酮在滑动时形成的转移膜对其摩擦学性能有重要影响,本文对此转移膜进行了Ｘ射线光电子能谱化学分析（ＥＳＣＡ）。表明,与纯聚醚醚酮和聚醚醚酮＋聚四氟乙烯相比,碳纤维增强聚醚醚酮形成的转移膜最薄,连续性与均匀性最好,因此其摩擦学性能最好。转移膜的成份沿着其深度方向发生变化,表明此膜中石墨和聚四氟乙烯存在着优先转移。在这一研究的基础上,本文对滑动摩擦转移膜的形成提出粘着转移机制。     

The tribological behavior of nanometer and micrometer TiO2 particle-filled polytetrafluoroethylene/polyimide

The friction and wear properties of micrometer and nanometer TiO₂ particle-filled polytetrafluoroethylene (PTFE)/polyimide (PI) composites were studied in this paper. The effect of filler contents (0.5%, 1%, 1.5%, 2%, 3%, 5% and 7 vol.%) on the tribological properties was examined. The transfer films and the worn surfaces of the PTFE/PI composites filled with micrometer and nanometer TiO₂ particles were investigated by using a scanning electron microscope (SEM). Experimental results show that anti-wear properties of the PTFE/PI composites can be improved greatly by filling nanometer TiO₂ particles. The wear rate of 1.5% nanometer TiO₂ filled composite is the lowest, which is about 52% lower than that of PTFE/PI. In the case of micrometer TiO₂ filler, the friction coefficient and wear rates increase with increasing filler volume fractions under identical test conditions. It was also found that the wear mechanism of micrometer TiO₂ particle-filled PTFE/PI is mainly severe adhesion and abrasive wear, while that of nanometer TiO₂ particle-filled PTFE/PI is mainly slight abrasive wear.     

聚丙烯腈填充聚四氟乙烯复合材料的结构表征及性能

将聚丙烯腈粉末填充改性聚四氟乙烯,利用傅立叶红外光谱(FT-IR)研究了聚合物在聚四氟乙烯复合材料烧结成型过程中的化学变化;用热失重分析(TGA)和动态力学分析(DM A)考察了聚四氟乙烯复合材料的热稳定性、动态力学性能的变化及两种聚合物的相容性。结果表明:(1)聚丙烯腈在烧结过程中发生了环化反应;(2)聚丙烯腈的加入使聚四氟乙烯复合材料的起始分解温度有所降低;(3)聚丙烯腈的加入提高了复合材料的玻璃化转变温度,但同时也使其低温动态模量降低。