金属陶瓷覆层-钢基体界面结合状态的研究

为提高钢基材料的耐磨性和耐腐蚀性,以金属Mo粉、Fe粉和B-Fe合金粉末为原料,采用原位反应真空液相烧结技术,在钢基体表面制备三元硼化物金属陶瓷覆层.测定了覆层-钢基体界面结合强度及界面结合区的显微硬度变化,研究了界面微观结构和界面区元素分布,并对覆层-钢基体界面层形成的机理进行了分析.结果表明,覆层与钢基体之间的断裂破坏发生于界面附近的钢基体和覆层内,而不是覆层与钢基体之间结合界面的剥离;在覆层-钢基体结合界面处,存在由高硬度覆层到低硬度钢基体的狭窄过渡区,合金元素的分布形成具有一定厚度的过渡层.     

Zn层添加AZ31/7075合金复合成形工艺及组织与性能研究EI北大核心CSCD

通过在异种材料界面添加厚度为100μm的Zn箔,采用预挤压与孔型轧制复合工艺成功制备出AZ31/7075复合材料,并利用光学显微镜(OM)、扫描电子显微镜(SEM)、能谱分析(EDS)对复合界面进行表征及显微硬度测试,探究Zn过渡层在挤压复合孔型轧制过程中对产品的影响。结果表明:7075硬质铝合金芯部可细化AZ31镁合金,引入Zn过渡层可减少或者避免镁铝系金属间化合物生成;挤压及变形温升使Mg-Zn互扩散形成的低熔点共晶相熔化,同时加速元素自固相向液相扩散;然而降温冷却使Mg-Zn扩散层易出现不连续裂缝,但后续孔型轧制可显著改善;Mg-Zn扩散层经变形生成的MgZn_(2)金属间化合物具备较高的显微硬度(161HV),但Mg-Zn扩散层变形后厚度则较薄,结合层整体硬度变化不明显。     

反应硼化烧结法制备三元硼化物基耐磨覆层材料

用反应硼化烧结法在 12 90℃± 5℃下真空烧结成功制备出三元硼化物基硬质覆层材料YF - 1,其表面硬质覆层的硬度可达 82 - 90HRA。用扫描电镜 (SEM)、X射线衍射 (XRD)和电于探针 (EPMA)对YF - 1的显微结构进行了分析 ,结果表明 :表面硬质覆层材料主要是由三元硼化物基硬质相和铁基粘结相组成 ,硬质相Mo2 FeB2 是在真空烧结过程中原位反应生成的 ;硬质覆层和基体Q2 35钢的界面为一较大区域 ,界面结合良好。对YF - 1进行的磨损试验表明此种覆层材料具有优异的耐磨性     

Co-Zn扩散偶的界面迁移

采用铆钉法制备了界面为曲面的Co-Zn扩散偶,利用光学显微镜观察了扩散偶界面特征,并测量了扩散层厚度.研究结果表明,经过扩散热处理,Co-Zn扩散偶界面处形成了一个扩散溶解层,该扩散溶解层的厚度随温度的升高和保温时间的延长呈增大趋势.在扩散偶热处理过程中,Co/Zn界面处形成的扩散溶解层向锌侧迁移的速度较大,出现了明显的kirkendall效应.     

Ni-Co/WC-Graphite复合熔覆层的组织与三点弯曲行为

采用真空熔覆技术制备了Ni-Co/WC-Graphite(G)复合熔覆层,采用SEM、XRD等分析了微观组织及相组成,利用三点弯曲研究了复合熔覆层的弯曲行为,并分析了断口形貌特征、微区元素分析与断裂机制。结果表明:整个Ni-Co/WC-G熔覆层包括复合层区、过渡层区、扩散冶金熔合带以及热影响扩散区,复合层区呈现三维织构组织特征,主要组成相有Cr_7C_3、Cr_(23)C_6、Ni_3Si、CrB、WC、C和γ-Ni-Co固溶体,扩散影响区主要组织为珠光体,扩散冶金熔合带及过渡层主要组成相为镍钴基合金固溶体及金属间化合物;具有复合熔覆层试样的三点弯曲载荷-位移曲线初始呈线性变化,而后曲线斜率逐渐减小,在达到载荷峰值时Ni-Co/WC-G复合熔覆层在承受压应力时溃裂,而在承受拉应力时断裂,由于过渡层、扩散冶金带以及热影响扩散区的存在,使载荷在熔覆层失效后仍在一定范围内缓慢增加,熔覆层区断口形貌呈沿晶或穿晶特征,基体侧的热影响扩散区呈扇形解理断裂特征,远离界面的基体区域为具有大量韧窝的韧性断裂。     

WC对CuNiSiB喷焊覆层材料耐气蚀性的影响

在CuNiSiB自熔合金粉末中添加不同量的硬质WC陶瓷颗粒，利用氧乙炔焰粉末喷焊工艺制备覆层材料，用超声波振动气蚀仪对覆层材料进行耐气蚀性能实验。用扫描电子显微镜对覆层表面气蚀破坏形貌进行观察。结果表明：复合覆层材料的耐气蚀能力比基体强，且随着WC颗粒加入量的增加，耐气蚀能力逐渐增大；提高CuNiSiB履层材料耐气蚀能力的途径是强化晶界。该文还探讨了覆层材料的气蚀机理。     

WC对CuNiSiB喷焊覆层材料耐气蚀性的影响

在CuNiSiB自熔合金粉末中添加不同量的硬质WC陶瓷颗粒 ,利用氧乙炔焰粉末喷焊工艺制备覆层材料 ,用超声波振动气蚀仪对覆层材料进行耐气蚀性能实验 ,用扫描电子显微镜对覆层表面气蚀破坏形貌进行观察。结果表明 :复合覆层材料的耐气蚀能力比基体强 ,且随着WC颗粒加入量的增加 ,耐气蚀能力逐渐增大 ;提高CuNiSiB覆层材料耐气蚀能力的途径是强化晶界。该文还探讨了覆层材料的气蚀机理     

铝合金表面激光熔覆铜镍合金涂层的组织、硬度与耐蚀特性研究

为提升铝合金材料的耐蚀性能,探究铝合金与合金熔覆层间的结合机理,本文利用激光熔覆技术在5083铝合金表面制备了不同Ni含量的铜镍合金熔覆层,并利用扫描电子显微镜、X射线衍射分析、硬度测试与电化学性能测试技术,分析了不同Ni含量的铜镍合金熔覆层相组成与组织形貌、铜镍合金熔覆层与铝合金基体的界面组织形貌,绘制了铝元素扩散曲线,分析了海水腐蚀过程中铜镍合金熔覆层的极化曲线。实验结果表明：所制备的铜镍合金熔覆层形貌良好无缺陷,熔覆层由网络状枝晶组成。对合金熔覆层进行XRD分析发现熔覆层主要由AlNi₃与CuNi两相组成。结合SEM、EDS分析,发现合金熔覆层的网络状枝晶为富铝相,即AlNi₃,晶间相为CuNi相。在硬度测试中,由于AlNi₃硬质相的生成,熔覆层硬度得到了提升且随着铝的向上扩散呈现一定的规律,电化学检测结果表明,铜镍合金熔覆层具有比5083铝合金更高的自腐蚀电位和较小的自腐蚀电流密度,可以有效提升5083铝合金在海水环境中的耐蚀性。     

嵌入HXNBR阻尼薄膜共固化复合材料制备及界面结合机理

基于环氧树脂基体的固化工艺和氢化羧基丁腈橡胶(HXNBR)的硫化特性。根据正交试验法研制出一组能够与环氧树脂在180℃发生共固化的粘弹性阻尼材料。将阻尼材料制成胶浆，探索使用刷涂法将玻璃纤维/环氧树脂预浸料制成带有阻尼薄膜的预浸料，最终根据平板硫化机固化工艺制备出共固化复合材料。通过层间剪切试验和微观结构分析，验证其配方的可行性。通过层间剪切试验，获得层间剪切强度随阻尼层厚度的变化曲线。利用傅里叶变换红外光谱和X射线光电子能谱，分析出HXNBR和环氧树脂之间存在化学作用。旨在探索HXNBR和环氧树脂的界面结合机理，提高界面结合性能。这为共固化阻尼复合材料的广泛应用奠定了基础。     

AgCu5-QSn6.5-0.1复合材料的热扩散研究

本文在实际生产条件下,模拟性地研究了热压AgCu5-QSn6.5-0.1复合材料中。Ag、Cu、Sn透过复合界面的扩散规律。利用扩散规律,可选择热压复合工艺参数,控制扩散层厚度,从而既保证AgCu5-QSn6.5-0.1)复合材料界面结合牢靠,又保证该材料满足各种使用性能要求。     

Vertical antiresonant reflecting optical waveguide coupler for three-dimensional optical interconnects: optimum design for large tolerance, high coupling efficiency, and short coupling length

A compact antiresonant-reflecting-optical-waveguide-(ARROW-) type vertical coupler for three-dimensional optical interconnects was demonstrated. The coupler consists of stacked ARROW's channeled by the stripe lateral confinement structure, and each waveguide is completely separated by a thin metal film in the separation region. In the coupling region the intermediate cladding of a previous coupler was made of the same material as that of the first cladding or the core. However, we had to overcome the problem that both the high coupling efficiency and the large fabrication tolerance cannot be achieved simultaneously. Thus we incorporated an intermediate cladding made of a material different from that of the core and the first cladding. The refractive index and the thickness of the intermediate cladding were optimally designed to achieve large fabrication tolerance and a short coupling length with a high coupling efficiency. The coupling length was reduced from 4.1 to 0.8 mm, and a high coupling efficiency of 96% was experimentally demonstrated.     

金属包覆材料固-液铸轧复合技术研究进展

金属包覆材料属于典型层状金属复合材料,是航空航天、石油化工、电力电子等领域的关键材料,其高效成形与性能控制技术一直是行业难点和国际研究热点.首先系统梳理了目前国内外金属包覆材料的典型制备工艺,并且根据初始时基体与覆层物理状态的不同将其分为3类,分别是固-固相复合法、固-液相复合法和液-液相复合法,对比分析了各种制备工艺的成形原理和主要特点.随后,从工艺原理、成形机理、复合机理、工艺优化等方面重点介绍了金属包覆材料固-液铸轧复合技术的最新研究进展.分析结果表明,以固-液铸轧复合技术为代表的融合塑性变形的固-液相复合工艺将成为行业未来一个重要发展方向,并且以固-液相复合法和液-液相复合法进行初态复合组坯,以固-固相复合法进行终态性能调控的一体化组合成形工艺具有良好发展前景.     

Dependence of bending losses on cladding thickness in plastic optical fibers

Our main goal is to provide a comprehensive explanation of the existing differences in bending losses arising from having step-index multimode plastic optical fibers with different cladding thickness and under different types of conditions, namely, the variable bend radius R, the number of fiber turns, or the fiber diameter. For this purpose, both experimental and numerical result of bending losses are presented for different cladding thicknesses and conditions. For the measurements, two cladding thicknesses have been considered: one finite and another infinite. A fiber in air has a finite cladding thickness, and rays are reflected at the cladding-air interface, whereas a fiber covered by oil is equivalent to having an infinite cladding, since the very similar refractive index of oil prevents reflections from occurring at the cladding-oil interface. For the sake of comparison, numerical simulations based on ray tracing have been performed for finite-cladding step-index multimode waveguides. The numerical results reinforce the experimental data, and both the experimental measurements and the computational simulations turn out to be very useful to explain the behavior of refracting and tunneling rays along bent multimode waveguides and along finite-cladding fibers.     

爆炸焊接布药工艺与微观结合界面形貌分析

爆炸焊接是复合材料加工的1项高新技术,不同的爆炸焊接布药工艺对复合板的质量有很大影响。通过对传统的均匀布药工艺和新不等厚度布药工艺进行爆炸焊接试验和理论分析,发现传统的均匀布药工艺所得到的焊接大波状结合界面明显、复合板质量不好,而新不等厚度布药新工艺可以使炸药产生的爆轰压力逐渐减少,并和材料本身振动产生的惯性力协调作用,得到基本一致的微小波状结合界面,同时降低震动和噪声。结论表明新工艺对工业生产和爆炸焊接试验有很好的指导作用。     

Two-Layer Nanocoatings in Long-Period Fiber Gratings for Improved Sensitivity of Humidity Sensors

A relative humidity sensor based on the deposition of electrostatic self-assembled alumina ( $hbox{Al}_{2}hbox{O}_{3}$) and poly(sodium 4-styrenesulfonate) on the cladding of a long-period fiber grating (LPFG) has been designed. The sensitive material has a lower refractive index than that of the fiber cladding, which limits the sensitivity of the LPFG response. In order to enhance its sensitivity, a previous high refractive index coating has been deposited. The overlay thickness is of the order of magnitude of the light wavelength used to interrogate the sensor. A theoretical model of multilayer cylindrical waveguides based on coupled-mode theory has been used to predict the phenomenon. Experimentally, an increased wavelength shift of the attenuation bands (75%) was obtained during the fabrication of the sensor, and, what is more important, the sensitivity was improved by a ratio of almost four. The proposed method improves the performance of LPFG-based sensors characterized by overlays of low refractive index.      

基于激光熔覆技术的热防护材料选择

轻量化合金材料的耐高温、抗烧蚀性能较差,采用激光熔覆技术制作涂层的方法可提升其热防护性能。本文从热防护的机理出发,结合激光熔覆工艺对熔覆材料性能的要求,从现有的热防护材料和激光熔覆材料中筛选出几种可实现短时间、无冷却情况下基体热防护的熔覆材料,并对基于激光熔覆工艺的热防护材料的未来发展趋势进行了展望。     

Photosensitive terpolymer for all-wet-etching process: Material characterization and device fabrication

A photosensitive terpolymeric composition suitable for practical waveguide devices is provided. The terpolymer was produced from pentafluorostyrene, perfluoro-n-octyl acrylate, and glycidyl methacrylate. We present a fabrication process where the device structure utilizes the same class of material for the core and cladding layers and it was fabricated without a plasma etching process. Based on the developed material and process; a 16-channel arrayed waveguide grating with good performance has been realized. During temperature cycling, a slight thickness hysteresis and refractive index hysteresis was observed above the glass transition temperature and is ascribed to the fact that the terpolymer material may not completely recover its elasticity in the heating/cooling cycle.     

Long-range surface plasmon polariton waveguides embedded in fluorinated polymer

Low-attenuation waveguides based on the propagation of long-range surface plasmon polaritons (LRSPPs) along thin Au stripes embedded in low absorption perfluorocyclobutane (PFCB) polymer are presented. A new low in propagation loss of <2.0 dB/cm was achieved for a 4 microm wide waveguide by optimizing the cladding material and fabrication process. The coupling efficiency between the LRSPP waveguide and the optical fiber is studied theoretically and experimentally for different widths of Au stripes and various cladding thicknesses. Lower coupling loss is found when the cladding thickness is close to the mode diameter of the butt-coupled fiber. Based on the 2D distribution of SPP modes calculated by a finite-difference mode solver, a symmetric structure of multilayer claddings with different refractive indices is proposed to optimize device insertion loss.     

Explosive scarf welding of aluminum to copper plates and their interface properties

Explosive welding was used to produce scarf joint between aluminum and copper plates. This process is known as explosive scarf welding (ESW). In a scarf joint, the final bond interface is oblique. In this study, chamfered end of aluminum and copper plates were joined explosively and named scarf joint, employing changes in chamfered angle at different stand‐off distance and explosive loading. The geometry of scarf joint enables consideration of both flyer and base plate thickness and explosive loading and the effects on mechanical properties of interface such as bond shear strength and micro‐hardness can be investigated. Mathematical models developed on the interface properties of scarf joint to make relationship between the bond shear strength and explosive loading ratio. To check the adequacy of developed models, mechanical properties of interface, such as bond shear strength was predicted and compared with actual values in explosive cladding process. The results show reasonable agreement with theoretical predictions. Consequently, mathematical model which is based on scarf joints, can predict bond shear strength of cladding metals under desired explosive loading and flyer plate thickness.