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1.
FRP(纤维增强复合材料)片材加固界面出现剥离损伤是影响FRP加固效果甚至引起结构脆性破坏的重要原因,实际工程中,剥离大都以补丁形式存在于FRP片材与被加固结构间,肉眼无法观察。将Mach-Zehnder光纤干涉仪的传感臂黏贴在FRP加固片材表面,用软胶榔头沿设定的位置在FRP件表面逐点加载。由光纤干涉仪测量每次加载时光纤的积分应变量,得出加载点与光纤积分应变量的关系曲线,从曲线的曲率或者正负值突变来判别补丁式剥离损伤的位置和大小。试验结果表明,该方法对于FRP加固结构补丁式剥离层具有较好的可测性。  相似文献   

2.
东华大学纤维材料改性国家重点实验室是我国材料和纺织领域重要的国家级科研基地,目前设有高性能纤维与复合材料、功能化纤维与低维材料、环境友好和生物纤维材料3个研究方向:其中在超高分子量聚乙烯的分子链缠结解离、高倍拉伸取向等基础研究上,攻克了高强高模量聚乙烯纤维制备关键技术和工程集成,打破了欧美技术封锁,使我国成为世界上3个拥有该项技术的国家之一,产量占全球30%;  相似文献   

3.
聚苯硫醚(PPS)是一种耐高温、耐化学腐蚀、阻燃的高性能材料,其纤维制品可广泛应用于高温过滤、化学防护等领域。通过纳米填料熔融复合技术,可显著提高PPS材料及其纤维的综合性能。详细介绍了国内外纳米填料对PPS及其纤维紫外光稳定性、热氧稳定性、结晶和力学性能、以及耐磨性的改性研究,并进一步分析了纳米粒子对PPS的改性机理。详述了目前PPS纳米复合改性研究的不足,提出相应的解决方案。指出了纳米改性研究首先需要提高PPS纤维的紫外光稳定性、耐热氧化性能和最高使用温度,以扩展PPS纤维的应用范围。综合分析表明,PPS纤维的纳米改性研究仍处于起步阶段,需深入对不同形貌、尺寸纳米填料复合改性及纳米复合纤维成形机理的研究,并拓宽其研究范围。  相似文献   

4.
高性能纤维的低温等离子体表面改性   总被引:7,自引:0,他引:7  
陈惠敏 《表面技术》1999,28(5):9-10
介绍了纤维材料的低温等离子体表面改性技术,并对其在改善高性能纤维粘着性的应用进行论述。  相似文献   

5.
提出了油气管线完整性技术服务系统,该技术系统成熟、全面、配套、实用性强,在多项工程中成功应用,实践证明这套方法符合我国油气输送管线实际。作者已经开发了新的涂层材料及其三合一喷涂生产系统。  相似文献   

6.
离子束表面工程技术的进展*   总被引:1,自引:1,他引:0  
综述了离子束表面工程技术近期研究进展,重点讨论了等离子体浸没离子注入(PIII)、强流脉冲离子束技术(HIPIB)、等离子体喷涂物理气相沉积(PS-PVD)、电子回旋共振(ECR)等离子体和磁过滤阴极真空弧沉积等表面工程技术;介绍了离子束表面工程在替代传统电镀技术、航空航天材料表面改性、太阳能利用中材料的表面改性、生物医学材料的表面改性等领域的应用。指出了离子束表面工程技术的未来研究方向,即深入研究离子束与材料表面的作用机理,开发高性能结构涂层和功能涂层,发展新的离子束复合表面技术。  相似文献   

7.
近年来,随着血管支架等医疗器械结构设计方法不断进步,相关监管法规和标准不断完善,钛镍合金医疗器械应用取得显著进展。多种类型钛镍合金医疗器械取得注册证,包括心血管、脑血管和外周血管器械。其中,心血管器械包括支架、心脏瓣膜和封堵器等。然而,钛镍形状记忆合金医疗器械仍面临镍离子释放防护和关键原材料进口替代等问题,亟待开发高疲劳钛镍合金原材料,包括丝材、管材和棒材;亟待开发记忆合金表面改性技术和相关医疗器械结构设计、性能测试评价技术;亟待完善相关器械测试方法标准和相关器械评审技术指导原则。需要制定相关标准,规范有限元分析中血管、血液边界条件和参数个性化设置,以及弥补体外模拟验证中血管、血液材料选择、血管力学和血液环境模拟、支架和血管交互作用模拟等方面的标准缺少的问题。  相似文献   

8.
随着高品质和高性能轻合金铸件的市场需求快速增长,先进的间接挤压铸造工艺有了巨大的应用市场.基于间接挤压铸造的工程实践,从挤压铸造机结构、工艺要素、生产控制等方面出发,讨论轻合金挤压铸件开发流程中需要注意的若干关键要素,并提出具有可操作性的技术解决方案.  相似文献   

9.
Cf/SiC复合材料的氧化及抗氧化技术研究进展   总被引:1,自引:0,他引:1       下载免费PDF全文
连续碳纤维增强碳化硅陶瓷基复合材料(Cf/SiC)因其具有高比强、高比模、耐磨损、良好热稳定性以及耐高温等突出性能,成为航空、航天、高性能武器装备等高尖端领域极具潜力的热结构材料。但高温氧化是其工程应用上的弱点,会造成Cf/SiC复合材料性能的下降,直接影响到材料的使用寿命和安全性。分析Cf/SiC复合材料的氧化影响因素,从界面相、基体和表面涂层3个方面综述Cf/SiC复合材料高温抗氧化技术的研究进展,结果表明:不同的温度区间内Cf/SiC复合材料的氧化行为不同,而界面改性、涂层抗氧化和基体改性相结合是实现材料抗氧化的关键。  相似文献   

10.
据业内专家认为 ,高性能的合成树脂和颜料、填料是防腐蚀涂料发展的关键。1.树脂。氟树脂 ,尤其是溶剂型氟烯烃共聚树脂的成功开发 ,是今后解决氯碱、农药、硫酸行业苛刻环境中腐蚀的有效途径之一 ;对氟涂料的研究上 ,要注重配套问题。聚苯硫醚 (PPS)、改性漆酚树脂等对较高温度强腐蚀的防护行之有效 ,是值得进一步开发与应用的品种。互穿聚合物网络 (IPN)、共混技术 ,是大分子层次上的设计 ,能够获得综合性能优良的合成树脂 ,可带锈涂装 ,在酸、碱、盐等苛刻环境中应用 ,并取得很好的防护效果。2 .颜料。开发低毒或无毒长效防锈颜料是当…  相似文献   

11.
In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.  相似文献   

12.
After nearly two years' tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry (SRIF), located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.  相似文献   

13.
Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.  相似文献   

14.
The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.  相似文献   

15.
The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).  相似文献   

16.
The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel.  相似文献   

17.
This work was to reveal the residual stress profile in electron beam welded Ti-6Al-4V alloy plates(50 mm thick) by using finite element and contour measurement methods.A three-dimensional finite element model of 50-mmthick titanium component was proposed,in which a column–cone combined heat source model was used to simulate the temperature field and a thermo-elastic–plastic model to analyze residual stress in a weld joint based on ABAQUS software.Considering the uncertainty of welding simulation,the computation was calibrated by experimental data of contour measurement method.Both test and simulated results show that residual stresses on the surface and inside the weld zone are significantly different and present a narrow and large gradient feature in the weld joint.The peak tensile stress exceeds the yield strength of base materials inside weld,which are distinctly different from residual stress of the thin Ti-6Al-4V alloy plates presented in references before.  相似文献   

18.
Silicon carbide nanoparticle-reinforced nickel-based composites(Ni–Si CNP),with a Si CNPcontent ranged from1 to 3.5 wt%,were prepared using mechanical alloying and spark plasma sintering.In addition,unreinforced pure nickel samples were also prepared for comparative purposes.To characterize the microstructural properties of both the unreinforced pure nickel and the Ni–Si CNPcomposites transmission electron microscopy(TEM) was used,while their mechanical behavior was investigated using the Vickers pyramid method for hardness measurements and a universal tensile testing machine for tensile tests.TEM results showed an array of dislocation lines decorated in the sintered pure nickel sample,whereas,for the Ni–Si CNPcomposites,the presence of nano-dispersed Si CNPand twinning crystals was observed.These homogeneously distributed Si CNPwere found located either within the matrix,between twins or on grain boundaries.For the Ni–Si CNPcomposites,coerced coarsening of the Si CNPassembly occurred with increasing Si CNPcontent.Furthermore,the grain sizes of the Ni–Si CNPcomposites were much finer than that of the unreinforced pure nickel,which was considered to be due to the composite ball milling process.In all cases,the Ni–Si CNPcomposites showed higher strengths and hardness values than the unreinforced pure nickel,likely due to a combination of dispersion strengthening(Orowan effects) and particle strengthening(Hall–Petch effects).For the Ni–Si CNPcomposites,the strength increased initially and then decreased as a function of Si CNPcontent,whereas their elongation percentages decreased linearly.Compared to all materials tested,the Ni–Si CNPcomposite containing 1.5% Si C was found more superior considering both their strength and plastic properties.  相似文献   

19.
A new method was introduced to achieve directional growth of Sn crystals. Microstructures in liquid(Pb)/liquid(Sn) diffusion couples were investigated under various static magnetic fields. Results show that the β-Sn crystals mainly reveal an irregular dendritic morphology without or with a relatively low static magnetic field(B0.3 T). When the magnetic field is increased to 0.5 T, the β-Sn dendrites close to the final stage of growth begin to show some directional character. With a further increase in the magnetic field to a higher level(0.8–5 T), the β-Sn dendrites have an enhanced directional growth character, but the dendrites show a certain deflection. As the magnetic field is increased to 12 T, the directional growth of the β-Sn dendrites in the center of the couple is severely destroyed. The mechanism of the directional growth of the β-Sn crystals and the deflection of the β-Sn crystals with the application of static magnetic field was tentatively discussed.  相似文献   

20.
韩磊 《腐蚀与防护》2015,36(1):84-90,94
综述了常见的电化学噪声数据处理方法,介绍了直流趋势剔除、统计分析、快速傅立叶变换(FFT)法计算功率谱密度(PSD)以及小波变换处理电化学噪声信号的基本过程,并阐释了各种数学处理及所得参数的物理意义。  相似文献   

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