聚四氟乙烯的表面处理与粘接

分析了聚四氟乙烯(PTFE)难粘接的原因,介绍了化学处理法、高温熔融法、辐射接枝法、低温等离子体处理法、气体热氧化法等PTFE常用的表面处理方法,介绍了PTFE常用的表面改性剂和粘接性能优良的新型PTFE粘接剂。     

低温空气等离子体处理对铝合金表面粘接性能的影响

为了提高铝合金与高分子材料之间粘接强度,采用低温空气等离子体预处理技术,对5083型铝合金表面进行活化处理。对铝合金表面的显微形貌、接触角、表面能、化学元素的成分及价态等理化性能进行了分析,对铝合金与环氧树脂的粘接性能进行了测试。结果表明:低温等离子体处理后铝合金表面的活性显著增加,水接触角由88.7°最低降至10.1°,表面能由19.21 mJ/m~2增加到74.04 mJ/m~2,表面氧元素含量明显增加,显微形貌及粗糙度未发生明显改变。铝合金板粘接后的拉剪强度随处理时间增加而增加,最高值达到12.4 MPa,较处理前提高了约4倍,表面氧元素的含量及活性增加是树脂与铝合金粘接性能提升的重要因素。     

聚四氟乙烯包覆丁腈橡胶的耐高温航空煤油性能

本研究利用聚四氟乙烯(PTFE)的耐介质性,并采用低温等离子体(LTP)处理对PTFE薄膜和丁腈橡胶(NBR5080)混炼胶进行了表面改性,再用高温胶黏剂粘接工艺制备了PTFE薄膜包覆的NBR5080硫化胶,测试了NBR5080包覆前后在100℃高温航空煤油中性能变化,对比分析了表面包覆PTFE对NBR5080耐高温航空煤油性能的影响。结果表明:随试验时间的延长,未包覆的NBR5080的质量、尺寸先增加后趋于稳定,微观形貌变化明显,拉伸强度、断裂伸长率显著下降;包覆了PTFE的NBR5080的质量、尺寸基本不变,微观形貌变化较不明显,拉伸强度、断裂伸长率出现较小的降低幅度。表面包覆PTFE薄膜能够保护丁腈橡胶,使其耐高温航空煤油性能有所提高。     

混氧等离子体射流对CFRP表面性质及粘接强度的影响

目的 探究不同氧气含量下大气压混氧等离子体射流特性,分析其对碳纤维复合材料（CFRP）表面理化性质的影响,研究其改善表面浸润性及粘接强度的机理。方法 采用大气压介质阻挡放电（DBD）,产生氦氧混合等离子体射流,对CFRP表面进行处理,研究了不同氧气体积分数射流对CFRP表面的作用效果,确定了相对较佳的氧气体积分数。借助接触角测量仪、扫描电子显微镜（SEM）、原子力显微镜（AFM）和X射线光电子能谱仪（XPS）等表面分析手段,对处理前后CFRP表面的润湿性、微观形貌、粗糙度和化学成分等进行测试分析。采用环氧树脂胶粘剂,分别对射流处理前后的CFRP与铝合金表面进行粘接,并测试不同表面的粘接强度。结果 随着氧气体积分数的增加,射流长度变短,温度逐渐下降。氧气处理所得表面的浸润性相比未混氧射流处理所得表面的浸润性明显提高。当氧气体积分数为0.75%时,所得表面浸润性相对最好。与纯氦等离子体射流相比,混氧射流处理后,表面环氧树脂铺展速率更高,说明表面对胶粘剂的亲和性相对较好,所得表面粗糙度也相对更低。XPS测试结果表明,混氧射流处理所得表面含氧官能团含量更高,表面能相对较高,故表面润湿性较好。结...     

开放式低温等离子体对树脂基复合材料表面处理性能研究

目的 采用开放式低温等离子体对树脂基复合材料表面处理,研究其对树脂基复合材料粘接性能的影响。方法 运用响应曲面法,对开放式低温等离子体加工工艺与树脂基复合材料表面自由能交互性进行研究。采用接触角测量仪、扫描电子显微镜(SEM)、三维形貌仪、X射线光电子能谱仪(XPS)、傅里叶红外光谱仪(FT-IR)等仪器对开放式低温等离子体处理前后复合材料的接触角与表面能、表面微观形貌与表面粗糙度、表面化学成分进行分析,使用万能试验机对处理前后复合材料的粘接强度进行研究。结果 输入功率、喷枪距离与试样移动速度3个响应因子中,喷枪距离对试样表面能的影响最为显著,其次是试样移动速度与输入功率。当开放式低温等离子体加工工艺为P=800 W,d=11.8 mm,v=10 mm/s时,表面能最大,从24.8 mJ/m²增加到78.3 mJ/m²,表面粗糙度与未处理试样相比提高了约2.5倍。处理后试样表面的氧元素含量明显增加,氧元素主要以含氧官能团的形式存在,材料表面极性增加。开放式低温等离子体对树脂基复合材料处理后,粘接试样平均拉伸剪切强度从16.6 MPa增加到27.5 MPa,粘接强度提高了约65.7%,粘接接头破坏形式从界面破坏到材料基材破坏。结论 开放式低温等离子体对树脂基复合材料表面处理后,能够有效地增加其粘接强度,树脂基复合材料润湿性与表面能、表面粗糙度以及表面含氧官能团数量增加,是粘接强度提高的主要因素。     

射频等离子体改性PTFE表面液滴撞击接触起电对润湿性的影响∗

液滴撞击固体表面是自然界的常见现象，研究超疏水表面的液滴撞击对其润湿性的影响，对于超疏水性材料的潜在应用具有重要的科学意义。采用 3、10、20 min 氧等离子体处理（OPT）和 1 min 八氟环丁烷等离子体聚合沉积（PPD）的等离子体方法改性聚四氟乙烯（PTFE）表面，获得具有不同尺寸和间距的微 / 纳米锥的超疏水 PTFE 表面，研究射频等离子体改性 PTFE 表面的液滴静态接触角、滚动角及液滴撞击动力学行为，分析在不同个数液滴撞击后 PTFE 表面的润湿性和液滴撞击行为变化，确定 PTFE 表面液滴撞击起电效应的影响机制。结果表明：通过 1~9 个液滴撞击后，PTFE 表面的静态接触角随撞击液滴数量增加而减小，导致静态接触角低于 150°；液滴滚动角随撞击液滴数量增加而增大，造成液滴滚动角高于 10°。 撞击液滴的接触时间随撞击液滴数量增加而增大，回弹系数随撞击液滴数量增加而减小。随撞击液滴数量增加，回弹液滴的正电荷和 PTFE 表面的负电压增大，PTFE 表面的负电荷对液滴产生强吸引作用，导致低粘附超疏水性被破坏。3 min OPT 和 1 min PPD 改性 PTFE 表面的纳米锥间距小，密度大，表面负电荷量增加明显，造成 PTFE 表面的疏水性降低的程度最显著。 研究结果可为改善超疏水稳定性的表面织构设计提供理论依据。     

抗微动损伤的表面工程设计

针对内燃机车16V280ZJ型柴油机连杆的微动损伤，在失效分析和接触力学分析的基础上，进行了表面工程技术可行性方案的比较，确定了固体润滑涂层的表面处理方案。研究采用了极图法，对粘接MoS2、粘接石墨、粘接PTFE和电刷镀Pb／Ni等4种涂层的性能和微动特性进行了定量比较，结果表明，粘接MoS2涂层具有最佳的抗微动损伤特性。实际应用表明，经表面工程设计选择的涂层显著提高了连杆部件的使用寿命。     

冷等离子体处理工艺对丁腈橡胶表面性能的影响

目的采用冷等离子体处理工艺(CPT)改善丁腈橡胶(NBR5080)的表面润湿性。方法采用Ar、空气和O2等3种气氛,通过调整工艺参数对NBR5080进行表面处理,测试NBR5080的静态接触角、计算表面能;用扫描电子显微镜(SEM)及原子力显微镜(AFM)观察表面形貌;X射线光电子能谱(XPS)测试分析表面的化学元素。结果 3种气氛处理后,NBR5080的静态接触角由91°分别降到25°,27°,35°,表面粗糙度由16.37 nm分别提高到97.78,75.12,59.58 nm;与聚四氟乙烯薄膜之间由不能粘接到剥离强度分别提高到44.2,40.6,32.3 N/m。结论 3种处理气氛均能改善NBR5080的表面润湿性,其中Ar气氛的处理效果最佳,处理工艺参数为功率100 W、时间600 s、压强30 Pa;处理后的NBR5080与PTFE的粘接性能明显提高;处理后NBR5080的表面润湿性变化存在时效性。     

提高辐射剂量计用金刚石膜电学性能的研究

针对目前金刚石膜存在电阻率低,使辐射剂量计器件的信噪比不大、X光灵敏度较低的问题,采用优化的氧等离子体和氮等离子体对生成膜进行原位后处理.结果表明氧等离子体处理比氮等离子体更能有效的刻蚀石墨等非金刚石成分;处理后样品生成膜的电阻率可提高至少4个数量级;优化的等离子体处理工艺能提高金刚石膜对X射线的响应.     

等离子体处理对CFRP筒状件内壁活化效果的影响∗

为解决碳纤维增强树脂基复合材料（CFRP）筒状件内壁表面化学惰性较高导致与金属涂层结合强度差的问题，采用射频辉光放电对其内表面进行活化处理来提高其表面活性。通过接触角测试和红外光谱分析，探究等离子体处理气压、射频电源功率、处理时间和离子种类对活化效果的影响。结果表明，经射频辉光放电等离子体处理后 CFRP 筒状件内壁表面等离子体活化效果明显，表面能显著提高。其他工艺参数相同情况下，活化效果随气压增大先提升后降低，随射频电源功率和处理时间的增大而提高，以氧等离子体活化效果最佳。其中，在处理气压 0.5 Pa、射频电源功率 500 W、处理时间 60 min、氧等离子体条件下效果最为显著，水和二碘甲烷的接触角分别由 71.29°、49.36°降低到 4.93°、5.39°，表面能从 38.85 mJ·m^?2 提升到 74.73 mJ·m^?2 。通过红外光谱分析，经等离子体处理后的 CFRP 中 C-H 和 C≡C 等非活性键被打断，带有 C=O 的醛基和羧基活性基团增多，浸润性大幅提高。活化后的 CFRP 基体与金属薄膜的膜基结合力由不足 0.1 MPa 提升至 0.49 MPa。研究通过射频辉光放电对 CFRP 筒状件内壁表面进行活化处理，为制备高结合强度的金属涂层打下基础。     

Mechanical strength of PET fibers treated in cold plasma and thermal exposed

As a followup to previous work, experiments with argon and oxygen Radio Frequency plasma treated polyethylene terepthalate (PET) exposed to 100 °C after cold plasma treatment were performed. Tensile tests results in monofilaments treated in oxygen and argon plasma for 5 s, 20 s, 30 s, and 100 s showed a decrease in the average tensile strength compared with the untreated fibers. It was also observed that the reduction in mechanical strength is more significant for argon plasma and very sensitive to the treatment time for oxygen plasma. Experimental data obtained from tensile tests in samples thermal exposed to 100 °C after plasma treatments indicate the same influence of treatment times on mechanical strength, as observed for cold plasma treated fibers. Furthermore, an increase in tensile strength when compared with the samples unexposed to 100 °C was observed. Scanning electron microscopy, used to analyze effects of cold plasma treatment on fibers surfaces, indicates differences in roughness profiles depending on the type of treatment. The distance of roughness interval, D_ri, was a parameter introduced to relate the fibers surface condition and average tensile strength. Statistical analysis of experimental data was performed to explain influences of treatment time, and environmental and temperature effects on mechanical properties.     

Tensile strength of radio frequency cold plasma treated PET fibers—Part I: Influence of environment and treatment time

This article reports on a series of experiments with polyethylene terepthalate (PET) treated in a radio frequency plasma reactor using argon and oxygen as a gas fuel, for treatment times equal to 5 s, 20 s, 30 s, and 100 s. The mechanical strength modification of PET fibers, evaluated by tensile tests on monofilaments, showed that oxygen and argon plasma treatment resulted in a decrease in the average tensile strength compared with the untreated fibers. This reduction in tensile strength is more significant for argon plasma and is very sensitive to the treatment time for oxygen plasma. Scanning electron microscopy (SEM) used to analyze the effects of cold plasma treatment of fiber surfaces indicates differences in roughness profiles depending on the type of treatments, which were associated with variations in mechanical strength. Differences in the roughness profile, surveyed through an image analysis method, provided the distance of roughness interval, D_ri. This parameter represents the number of peaks contained in a unit length and was introduced to correlate fiber surface condition, before and after cold plasma treatments, and average tensile strength. Statistical analysis of experimental data, using Weibull cumulative distribution and linear representation, was performed to explain influences of treatment time and environmental effects on mechanical properties. The shape parameter, α, and density parameter, β, from the Weibull distribution function were used to indicate the experimental data range and to confirm the mechanical performance obtained experimentally.     

Improving carbon fiber adhesion to polyimide with atmospheric pressure plasma treatment

Plasma treatment is frequently used to modify carbon fiber surfaces to improve adhesion of the fiber to matrices although it may also influence carbon fiber tensile strength. In order to determine the effect of atmospheric pressure plasma treatment on carbon fiber tensile strength and interfacial bonding strength to polyimide, polyacrylonitrile (PAN) based carbon fibers are treated with atmospheric pressure oxygen/helium plasmas for different durations. Tensile strength change of the fiber is studied at different gage lengths before and after the plasma treatment. Interfacial bonding between the carbon fiber and a thermoplastic polyimide matrix is evaluated using a single fiber composite test system. Weibull analysis of the single fiber tensile test data shows no obvious changes in the tensile strength at short gage lengths after plasma treatment while the fiber strength tends to decrease at larger gage lengths. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) show that the plasma treatments roughen the fiber surfaces. X-ray photoelectron spectroscopy (XPS) analysis of fiber surface shows a significant increase of oxygen concentration after plasma treatment and the oxygen containing functional groups reach their maximum levels after 32 s treatment time and further increasing treatment time does not achieve a higher level of oxidation. Plasma treatments decrease dynamic water contact angles and increase the surface energy of the carbon fibers as measured by the modified Wilhelmy method. The interfacial shear strength is improved 21% after the atmospheric pressure plasma treatment for 32 s. It is concluded that the increase of oxygen containing functional groups and changing of the surface topology may contribute collectively to the improvement of fiber/resin interfacial adhesion.     

Surface modification of high performance PBO fibers using radio frequency argon plasma

The radio frequency argon plasma was applied to improve surface properties of the PBO fiber. The fiber tensile strength was measured, and the surface chemical components, topography and wettability were analyzed by X-ray photoelectron spectroscopy (XPS), atomic force microscopy and dynamic contact angle analysis (DCAA), respectively. Results suggested that over 90% of the fiber tensile strength was reserved after treatment at lower power levels. The surface oxygen atoms increased with a very small extent and the O/C ratio increased from 0.25 to 0.29. The plasma sputtering caused scission of chemical bonds and damage to the surface crystallizing layers, and thus created many active functional groups and roughened surface. However, at high power conditions the more effective ablation and sputtering effects dramatically reduced the tensile strength, surface oxygen contents and roughness. The fiber surface wettability was markedly increased as a result of the functionalization and roughening effects, but the calculated polar and dispersive free energy did not agree well with the measured surface chemical components due to the different effective depths of the surface layers analyzed by DCAA and XPS. The increased roughness was considered to be another reason. The treated fiber exhibited better adhesion with bismaleimide resin, but the maximum interlaminar shear strength of the PBO/bismaleimide composite could not be reproduced by increasing the treatment time at lower power level conditions.     

Aging of surface properties of ultra high modulus polyethylene fibers treated with He/O2 atmospheric pressure plasma jet

To investigate the relationship between aging of the treatment effect and the gas composition of atmospheric pressure plasma treatment, ultra high modulus polyethylene (UHMPE) fibers were selected as a model fiber to study the aging behavior of fiber surface treated by atmospheric pressure plasma jet (APPJ) with pure helium, helium + 1% oxygen, and helium + 2% oxygen. Atomic force microscopy showed increased surface roughness, while X-ray photoelectron spectroscopy revealed increased oxygen contents after the plasma treatments. The plasma treated fibers had lower contact angles and higher interfacial shear strengths to epoxy than those of the control fiber. Adding 1% of O₂ to helium increased effectiveness of the plasma in polymer surface modification and suppressed aging after the treatment, while adding 2% of O₂ had a negative effect on the APPJ modification results and accelerated aging. In addition, no significant difference in single fiber tensile strength was observed between the control and the plasma treated fibers.     

成形气氛中氧含量对激光沉积TA15钛合金组织及力学性能的影响

采用激光沉积制造技术制备了TA15钛合金厚壁件,通过光学显微镜(OM)和扫描电子显微镜(SEM)及拉伸试验对其显微组织、断口及力学性能进行分析,研究成形气氛中氧含量对激光沉积TA15钛合金组织及力学性能的影响。结果表明:随着气氛中氧含量增加,沉积态和退火态试样的显微组织均为典型网篮组织无明显变化。沉积态试样的室温抗拉强度提高而塑性下降,氧含量保持在5×10~(-5)以下能获得较好的综合力学性能。退火态试样的显微硬度低于沉积态且两者均随氧含量增加逐渐提高。室温拉伸断口的断裂机制随着氧含量增加由韧性断裂变为半解理半韧性断裂。     

Prediction of microstructure and mechanical properties of line pipe welded joints based on hardness map

In this article, the variation of hardness in cross-section of X52 microalloyed steel joints before and after post-weld heat treatment and also the relationship of hardness with ultimate tensile strength, yield strength and microstructure have been investigated. For this purpose, the specimens were prepared in two conditions of as welded and post-weld heat treated, and the hardness maps of their cross-section were provided. Then, some equations were suggested to correlate the obtained hardness with the grain size and tensile and yield strengths. The equations made it possible to predict tensile and yield strengths with high accuracy. According to the results, the maximum hardness and strength belong to the weld junction. Normalisation of the joints at 950°C reduced significantly the hardness difference (and also the strength difference) in various joint areas and homogenised the microstructure considerably. The grain size distribution was also modelled acceptably for the post-weld heat treated joint, and the grain size map was obtained.     

Effect of oxygen content on tensile strength of polymer-derived SiC fibers

Air-curng is usually applied to the polymer-derived SiC fibers and,as a result,oxygen is embedded to the material.An effective relationship between oxygen content of the SiC fibers and mass gain of their precursor fibers was established.Results also showed that oxygen content has a great influence on the mechanical properties and excellent tensile strength is usually obtained at the oxygen content of 12%-13%,similar to the density of SiC fibers.Oxygen content has a positive effect on the ceramic yield,and thus,is good to the density and tensile strength;while,oxygen content is also negative to volume content of SiC phase and crystallization of the SiC fibers,and thus,detrimental to the density and tensile strength.Both of the two effects result in the peak behavior of the tensile strength of SiC fibers.     

Sn对AZ61镁合金微观组织与力学性能的影响

研究了Sn对AZ61镁合金显微组织和力学性能的影响。对显微组织的观察表明，当加入Sn之后，在铸态和热处理态合金中均发现了球形颗粒状的Mg：Sn。对合金力学性能的试验表明，少量的Sn可提高合金的抗拉强度和屈服强度。热处理态下，当Sn含量达到3％时合金的抗拉强度和屈服强度分别达到了274MPa和172MPa，但是伸长率下降到9％。拉伸断口的SEM形貌分析表明，加入Sn以后，合金断裂方式由解理断裂向准解理断裂转变。