在聚酰亚胺表面构筑含微纳米SiO2颗粒涂层的方法研究

目的 研究一种将St?ber法制备的SiO2纳米微球分散在含硅溶胶体系中,在聚酰亚胺(PI,Kapton)表面制备含SiO2微纳米颗粒涂层的新方法,并利用该涂层提高Kapton薄膜的使用寿命和抗原子氧(atomic oxygen,AO)侵蚀能力.方法 用正硅酸乙酯(TEOS)在碱性条件下制备St?ber微球,用3-氨丙基三乙氧基硅烷(APTES)在酸性条件下制备含硅溶胶.将St?ber微球均匀分散到溶胶中,用提拉镀膜方法在经低浓度NaOH水热处理后的Kapton薄膜表面,制备含SiO2微纳米颗粒的涂层.在束流密度为1.43×1016 atoms/(cm2·s),辐照时间为6 h的AO环境中进行模拟试验.用SEM扫描电镜和AFM原子力显微镜表征试验前后样品的表面形貌.结果 AO辐照后,原始Kapton薄膜的质量损失和AO侵蚀率分别为1.39 mg/cm2和3.17×10?24 cm3/atom,且Kapton表面被严重侵蚀;而有涂层的Kapton样品,质量损失和AO侵蚀率分别下降为0.10 mg/cm2和0.22×10?24 cm3/atom,侵蚀率只相当于原始Kapton的6.9％.结论 采用St?ber与sol-gel相结合的方法,提高了所制备涂层中SiO2的含量.模拟试验表明,该涂层提高了样品的抗AO侵蚀能力.此制备方法简单实用,对于长寿命航天器中聚合物材料的AO防护,具有一定的研究意义.     

甲基苯基二甲氧基硅烷含量对光固化有机硅 / SiO2杂化涂层性能的影响

目的获得耐热性和耐蚀性好,且可紫外光固化的有机硅/SiO2杂化涂层,研究甲基苯基二甲氧基硅烷(PDMS)含量对涂层性能的影响。方法以正硅酸乙酯(TEOS)为SiO2前驱物,PDMS与γ-(甲基丙烯酰氧)丙基三甲氧基硅烷(KH-570)为有机硅前驱物,采用溶胶-凝胶法制备PDMS含量不同的有机硅/SiO2杂化溶胶,经光固化后,得到有机硅/SiO2杂化涂层。对涂层进行机械性能测试,以及红外光谱分析、热重分析和电化学阻抗谱分析。结果前驱物均水解完毕并发生缩合反应,从而得到了有机硅/SiO2杂化涂层;随着PDMS含量的增加,杂化涂层的硬度降低,耐冲击性、柔韧性和附着力良好且变化不大。结论 PDMS的加入有利于提高涂层的综合性能,当n(TEOS)∶n(PDMS)∶n(KH-570)=15∶16∶7时,有机硅/SiO2杂化涂层的耐热和耐蚀性能达到最佳。     

氯化铈掺杂对6061铝合金表面硅烷膜性能的影响

采用极化曲线、硫酸铜点滴、盐水浸泡等方法,研究了稀土氯化物对铝合金表面γ-(甲基丙烯酰氧)丙基三甲氧基(KH-570)硅烷膜耐蚀性能的影响。结果表明,在KH-570硅烷膜制备过程中添加一定量CeCl3可有效提高硅烷膜的耐蚀性;扫描电子显微镜(SEM)显示:未含CeCl3的硅烷膜表面有轻微裂痕,而含量为0.2%CeCl3的改性硅烷膜表面较为均匀致密。在本试验工艺条件下,硅烷溶液中CeCl3的最佳含量为0.2%。     

溶胶-凝胶法制备硅铝溶胶增强有机/无机复合薄膜

以甲基三甲氧基硅烷(MTMS)的水解缩聚产物作为主要成膜物质、正硅酸乙酯(TEOS)和异丙醇铝的水解缩聚产物硅溶胶和铝溶胶作为无机增强物、甲基丙烯酰氧基丙基三甲氧基硅烷(KH-570)作为表面改性剂,通过共缩聚反应在聚碳酸酯(PC)板表面制备硅铝溶胶增强有机/无机复合薄膜;采用乌氏粘度计、TG/DTA、FTIR、UV-VIS、金相显微镜、铅笔硬度测试方法及划格法对涂膜液及薄膜性能进行表征.研究结果表明,加入KH-570改性铝溶胶后的涂膜液稳定性较好,MTMS水解缩聚产物与硅溶胶、铝溶胶通过共缩聚反应在PC板表面形成带有机基团的无机交联网络结构,基本骨架由Si-O-Si、Si-O-Al、Al-O-Al组成;铝溶胶的引入提高了薄膜的耐热性能及薄膜硬度,但KH-570改性的效果不明显;薄膜对PC片有增透效果,涂膜液陈化2 d后,加入KH-570改性铝溶胶后薄膜的增透效果更理想;加入KH-570改性铝溶胶后薄膜的表面平整性得到改善.     

环境因素对聚酰亚胺薄膜及涂层侵蚀效应分析

目的采用不同表面改性方法处理聚酰亚胺,研究温度、湿度、紫外辐照和原子氧等环境因素对聚酰亚胺基体及涂层的侵蚀效应。方法用碱性溶液(NaOH)、硅烷偶联剂(KH-550)分别在水热及溶剂热条件下处理聚酰亚胺薄膜。用溶胶凝胶法制备二氧化硅溶胶,并在改性后的聚酰亚胺薄膜表面制备二氧化硅涂层。处理后样品的亲水性变化由接触角测量仪测定,透光率用紫外可见分光光度计表征,表面形貌用扫描电镜观察,表面结构变化由傅里叶变换红外光谱仪测定。环境效应试验用紫外老化箱和原子氧模拟试验装置进行评价,并用扫描电镜和材料显微镜表征环境因素对涂层产生的影响和破坏作用。结果实验得出的最佳表面处理条件为:(1)NaOH浓度0.1 mol/L,水热温度120℃,时间60 min;(2)20vol%KH-550+80vol%Et OH,溶剂热温度180℃,时间60 min。在此条件下处理后的聚酰亚胺基体与二氧化硅涂层界面结合较牢固。结论使用碱液水热处理与硅烷偶联剂溶剂热相结合的处理方法,可有效改善Si O2涂层与聚酰亚胺基体的界面粘附性。所制备的涂层均匀致密,具有很好的抗原子氧侵蚀能力,但在储运过程中必须注意环境湿度对涂层产生的破坏作用。     

基于磁控溅射–氟化改性的新型ZnO/SiO2复合超疏水涂层防冰性能研究

目的 通过磁控溅射及表面氟化修饰不同纳米尺度的氧化锌(ZnO)和二氧化硅(SiO2)粒子,获得一种新型的ZnO/SiO2复合超疏水涂层。方法 研究不同氟化修饰剂对新型ZnO/SiO2复合超疏水涂层防冰性能的影响。采用光学接触角测量仪、扫描电子显微镜(SEM)、傅里叶红外光谱仪(FTIR)对涂层的水接触角(CA)、滚动角(SA)、微观膜层形貌以及氟化前后化学键的改变进行分析。采用自制结冰装置及数显拉力计对涂层在高湿低温环境中的结冰时间和冰层在涂层表面的黏附强度进行测试。结果 磁控溅射ZnO和SiO2纳米粒子复合制膜得到的粒子排列状态规则,并且两种不同尺寸粒子的掺混使得涂层表面呈多簇状微纳米二级结构,能够很好地降低液滴与表面的附着力;分别选用十七氟癸基三乙氧基硅烷(FAS-17)、聚二甲基硅氧烷(PDMS)、十二氟庚基丙基三甲氧基硅烷(G502)、十六烷基三甲氧基硅烷(HDTMS)4种氟化修饰剂对涂层表面进行整体修饰,其中,FAS-17修饰后的涂层表面防冰效果最好,其液–气复合接触面积比例达到了94.38%,接触角和滚动角达到最佳,分别为164.7°和3°,且冰在表面的黏附强度降低至3.8 kPa;在湿度为60%,温度分别为–2、–10及–20 ℃的条件下,涂层延缓结冰时间分别为244 6、160 4、137 s。结论 采用不同纳米尺度的ZnO和SiO2纳米粒子,经过磁控溅射和整体表面改性可以得到簇状结构的新型复合超疏水涂层。通过FAS-17乙醇溶液进行表面氟化修饰,更加显著地提高了涂层的超疏水性能。     

溶胶凝胶法制备光学透明的含氟超疏水复合涂层（英文）

以正硅酸乙酯(TEOS)、γ-缩水甘油醚氧丙基三甲氧基硅烷(GPTMS)、甲基三乙氧基硅烷(MTES)和十七氟癸基三甲氧基硅烷(FAS)为前驱体,通过溶胶凝胶法分别独立制备3种特性不同的溶胶。然后,通过逐次浸涂,依次构筑涂层的基底层、结构层和修饰层。最后,经过一次热处理工艺制备出复合超疏水涂层。采用扫描电镜,原子力显微镜对涂层的表观形貌进行表征,紫外-可见光谱和水接触角测量仪表征涂层的可见光透过率和疏水性能,同时测试了涂层的硬度,附着力等机械性能。结果表明,涂层对水接触角可达155°,可见光透过率高于70%。     

甲基丙烯酸酯交联改性二氧化硅涂层的制备和性能研究

不饱和C=C双键表面修饰的二氧化硅粒子采用正硅酸乙酯和γ-甲基丙烯酰氧丙基三甲氧基硅烷(KH-570)共水解制备,然后加入甲基丙烯酸甲酯单体和引发剂原位聚合生成PMMA接枝改性二氧化硅溶胶.将该有机-无机复合溶胶旋转涂覆到金属基片(黄铜及不锈钢)上,经90～120℃热处理2 h制备了复合涂层.采用傅立叶变换红外光谱、X-射线衍射、透射电镜表征了涂层结构和形貌,同时用激光光散射、铅笔硬度仪等对溶胶粒径和涂层性能进行了测试.结果表明该方法制备的PMMA-二氧化硅体系在一较宽的浓度范围内都能形成透明的稳定溶胶,接枝改性后的二氧化硅纳米粒子在聚合物中分散均匀,涂层机械强度明显提高,对金属基底具有良好的附着效果.     

硅烷对紫外线辐射下木粉/聚偏氟乙烯复合材料的影响（英文）

木粉表面分别经乙烯基三乙氧基硅烷(A151)、γ-氨丙基三乙氧基硅烷(KH550)、三氟丙基三甲氧基硅烷(TF3)和1H,1H,2H,2H-全氟癸基三甲氧基硅烷(TF17)修饰后,与聚偏氟乙烯(PVDF)熔融共混并挤出制备木塑复合材料(WPCs)。对暴露于紫外线辐照前后的复合材料进行力学测试、动态机械分析(DMA)和差示扫描量热分析(DSC)。结果表明,含有40 wt%TF3改性木粉的复合材料的抗弯曲和抗冲击性能得到显著提升,该复合材料在紫外线辐照条件下难以变联。TF17通过氟硅烷与PVDF之间产生的共价键使得复合材料暴露于紫外线辐照下容易交联。硅烷修饰填料表面可以改善填料粒子分散在聚合物基体中,但会阻断聚合物包埋于木材的毛细管中,这样能增加非晶态聚合物相的移动和降低木粉/聚偏氟乙烯复合材料的玻璃化转变温度(T_g)。暴露于紫外线辐照过程中,同时发生在复合材料固态非晶相和结晶相的交联和断链反应是相互竞争的。当非晶态相的反应占主导地位时,分子链重排和形成新的晶体,复合材料的熔融焓(AH_f)和结晶度(X_e)增加。     

SiO2-K2SiO3涂层对空间材料Kapton的防护行为研究

在微波电离型原子氧(AO)源地面模拟设备中对空间材料Kapton及SiO2-K2SiO3无机-有机复合涂层进行原子氧剥蚀效应试验．用扫描电镜(SEM)、光电子能谱(XPS)、红外光谱(FT-IR)、X射线衍射光谱(XRD)和LAMBDA-9分光光度计，对在模拟原子氧(AO)环境中Kapton及在其表面涂覆的涂层所发生的侵蚀与防护作用进行了表征研究，AO对Kapton表现了较严重的侵蚀作用，表面呈现粗糙，失去原有光滑和透明，而施加的SiO2-K2SiO3涂层。经AO辐照后，表面却变化甚少。实验表明，该涂层对AO辐照有较强的防护效果，有较好的空间稳定性，能阻止AO对基材的侵蚀。     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

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.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

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.     

Thermodynamics Study on the Decomposition of Chromite with KOH

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.     

Influence of Heat Treatment on Damping Behaviour of the Magnesium Wrought Alloy AZ61

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.     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

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).     

Quantitative Analysis of the Crystallographic Orientation Relationship Between the Martensite and Austenite in Quenching–Partitioning–Tempering Steels

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.     

Using Finite Element and Contour Method to Evaluate Residual Stress in Thick Ti-6Al-4V Alloy Welded by Electron Beam Welding

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.     

Microstructures and Tensile Properties of Ultrafine-Grained Ni–(1–3.5) wt% SiC_(NP) Composites Prepared by a Powder Metallurgy Route

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.     

Directional Growth of Tin Crystals Controlled by Combined Solute Concentration Gradient Field and Static Magnetic Field

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.     

Growth Kinetics of Single Inclusion Particle in Molten Melts

On the basis of the single-particle framework, a new theory on inclusion growth in metallurgical melts is developed to study the kinetics of inclusion growth on account of reaction and collision. The studies show that the early growth of inclusion depends on reaction growth and Brawnian motion collision, and where the former is decisive, the late growth depends on turbulence collision and Stokes＇ collision, and where the former is dominant; collision growth is very quick during the smelting process, lessened in the refining process, but nearly negligible in the continuous casting process.