共查询到20条相似文献,搜索用时 109 毫秒
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为了提高轧辊表面涂层的抗热冲击性能、延长其高温条件下的使用寿命,采用5kW CO2激光器,对轧辊表面等离子喷涂热障涂层进行了重熔处理。利用扫描电镜和能量色散谱仪,观察激光重熔涂层的涂层形貌和微观结构, 对分界面元素进行了微区成分分析。将试样在1000℃下保温10min后,放入常温(25℃)水中激冷,探究其抗热冲击性能,并与等离子喷涂涂层进行了对比。结果表明,经激光重熔后,涂层孔隙、裂纹明显减少,涂层质量明显提高;涂层与基体之间在一定程度上实现了冶金结合,结合强度明显提高;开始出现裂纹以及最终失效时的冲击循环次数由原来的14次和32次分别提高到43次和94次。该激光重熔工艺有助于提高涂层的热冲击性能,可延长轧辊的使用寿命。 相似文献
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在激光熔覆NiCrBSiC自熔合金粉末中添加不同含量的V2O5,通过改变激光功率、扫描速度、预涂厚度,进行了不同工艺条件下的单道及多道搭接试验.实验表明,V2O5的含量、激光熔覆的工艺均对熔覆层的形貌、组织、性能以及降低裂纹的敏感性有明显的影响.通过各个试验样品的对比分析,探讨了工艺和粉末成分对熔覆层性能及裂纹敏感性的影响,分析了多道搭接裂纹的分布规律及影响因素. 相似文献
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V2O5/NiCrBSi激光熔覆层开裂敏感性研究 总被引:3,自引:0,他引:3
在 4 5 #钢表面进行了对NiCrBSi合金粉末添加V2 O5的激光熔覆试验。通过优化激光熔覆工艺参数及V2 O5含量的优选 ,得到了质量良好、无裂纹且与基底冶金结合的熔覆层。实验表明 ,随V2 O5含量的增加 ,V2 O5对降低裂纹敏感性的作用逐渐明显直至最终消除裂纹。采用X射线衍射、扫描电镜对显微组织的观察分析表明 ,V2 O5降低熔覆层裂纹敏感性归因于V2 O5能够在快速凝固过程中起到均匀细化枝晶组织、抑制粗大块状脆性硬质相和提高覆层韧性的作用。 相似文献
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为了研究复合涂层中碳化钨(WC)组织演变对裂纹产生的影响机理, 采用单层激光熔覆、过渡层梯度熔覆与双层熔覆制备3种Ni50A/WC复合涂层对比的方法, 分析涂层的形貌与组织、裂纹产生特点以及原因, 探究WC的组织演变对裂纹产生的影响。结果表明, 不同熔覆方法的WC组织演变对裂纹产生的影响主要由残余WC颗粒内部开裂形成裂纹源、硬质相元素引起成分偏析等作用组成; 双层熔覆、梯度熔覆涂层与单层熔覆涂层相比, 由于粉末吸收了更多的能量, 残余WC颗粒含量降低了32.7%与37.9%, 减少了涂层内部裂纹源; 共晶化合物的W元素质量分数也从单层熔覆涂层的0.534分别下降到双层熔覆涂层的0.417与梯度熔覆涂层的0.386, 降低了硬质相元素集中程度, 减少了涂层成分偏析, 降低了涂层开裂敏感性。该研究对改善激光熔覆复合涂层的开裂问题、提高复合涂层的成品率有一定的指导意义。 相似文献
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采用光纤激光器和同轴送粉系统在SUS304不锈钢表面制备出钴基合金(Stellite-6)与碳化钒(VC)混合粉末的激光熔覆层。试验中分别采用每层成分不变的多层熔覆工艺(普通熔覆工艺)和每层成分变化的功能梯度熔覆工艺,对比研究了两种熔覆工艺方法的熔覆层裂纹敏感性、组织特征和性能。结果表明,功能梯度熔覆层与普通熔覆层相比较,在成分、组织和性能基本相同的情况下,裂纹敏感性低,能有效地防止裂纹出现;另外,Stellite-6与VC混合合金粉末熔覆层的显微组织根据VC含量的不同,可以分为亚共晶组织和过共晶组织。 相似文献
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Mo对高硬度镍基合金激光熔覆层组织和耐磨性的影响 总被引:10,自引:0,他引:10
采用激光熔覆技术, 在45#钢表面进行了镍基合金粉末添加Mo的熔覆试验,通过对激光熔覆工艺参数及Mo含量的优选,获得了成形良好、无裂纹、组织致密的熔覆层。对熔覆层横断面进行了显微硬度测量和显微组织分析,对各种Mo含量的熔覆层试样进行了摩擦磨损试验。结构表明:Mo能够提高高硬度镍基合金激光熔覆层的韧性、耐磨性,细化熔覆层的组织,降低熔覆层的裂纹敏感性。Mo对Ni60镍基合金激光熔覆层的改善归因于Mo对熔覆层组织的均匀细化、对粗大针状脆性硬质相的抑制以及对韧性相成分的提高作用。 相似文献
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采用CO2横流激光在40Cr钢表面熔覆不同配比的钴基合金粉末,采用摩擦磨损试验机测试试样的摩擦磨损性能。对摩擦系数以及耐磨性均较高的试样,采用微观分析及力学性能测试手段对熔覆层显微组织、物相、成分进行比较研究。结果表明:在现有实验条件下,激光熔覆层的强化相呈现网络状加弥散分布的颗粒状使裂纹或者缺陷的萌生门槛值增加,裂纹扩展速率减慢,导致钴基合金激光熔覆层的摩擦系数和耐磨性能的协同提高。 相似文献
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为了提高低碳钢表面的耐磨性能,采用CO2激光堆焊系统,将Co基合金与WC混合粉末(WC的质量分数为0~0.47)用单道堆焊于低碳钢表面。利用X射线衍射仪、能谱分析仪、扫描电子显微镜、激光显微镜、维氏硬度计和耐磨试验机对单道堆焊层的相结构、显微组织、维氏硬度、耐磨性和裂纹敏感性进行了比较分析。结果表明,这种堆焊方法的堆焊层均为亚共晶组织,且未分解WC弥散分散在Co基合金的基体上;堆焊层的维氏硬度均随WC含量的增加而增加。该方法具有较低的裂纹敏感性。 相似文献
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在圆锥轧辊轧制带钢时,为了增强轧辊与带钢之间的摩擦力,采用对轧辊表面进行激光毛化的方法,对圆锥轧辊的激光毛化加工过程进行了分析研究,给出加工系统的硬件组成,介绍了加工系统的控制原理。由于在圆锥轧辊表面进行激光毛化属于变径加工,为了保证每个加工圆周处毛化点之间的点距不变,推导出每个加工圆周处圆周直径、总脉冲个数和分频系数等的计算公式,同时给出相应算法,解决了每个加工圆周处最后1个毛化点与第1个毛化点之间间距总是大于点距的问题。结果表明,在圆锥轧辊表面进行激光毛化,不仅增强了轧辊与带钢之间的摩擦力,同时还延长了轧辊的使用寿命。 相似文献
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In recent years, roller imprinting has been considered as the most efficient technique for replicating microstructures onto polymeric substrate. However, the preparation of roller is still a challenge. This paper reports an effective method of directly fabricating microstructures on metal rollers; the process includes dip coating of the photoresist on the roller, stepped rotating lithography and electroless nickel plating. The facilities for dip coating and stepped rotating lithography have been implemented. The positive photoresist (EPG510) is first uniformly coated on the roller surface using dip coating process. The microstructures on the roller can be then defined by using stepped rotating photolithography with a glass mask, followed by electroless nickel plating. Rigid microstructured roller can be obtained. The experimental results show that the dip-coated film thickness on the roller increases with the withdrawal velocity of the roller from the resin bath. The coated photoresist on the roller surface is uniform. The microstructures have been successfully fabricated onto the metal roller using the stepped rotating lithography; the rigid nickel microstructures with various pitches on metal roller can be fabricated by adjusting the rotating degree of stepped rotating lithography. 相似文献
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小波包变换不仅能检测非平稳信号的整次谐波,还能检测信号的非整次谐波,而且小波变换本身对信号的奇异点十分敏感,因此可以用来跟踪牙轮钻机振动信号。简述了小波包变换的原理,并基于Matlab实现了对牙轮钻机振动信号的处理。该处理具有信噪分离、测量牙轮钻机振动功率谱、牙轮钻机振动信号的时域-频域变化规律、牙轮钻机振动速度信号三维图、伴有噪声的原始振动波形和噪声波等测量功能。实测某矿山YZ-35C牙轮钻机的振动速度信号,实测效果优于P3562A动态信号分析仪的测量结果,结果表明该方法是可行的和有效的。 相似文献
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A microactuator consisting of a plane wafer with striped electrodes covered with an insulation layer and thin cylindrical rollers was designed. When voltage is applied between the striped electrodes and the roller, the electric field between them attracts the roller, causing it to roll. As the roller passes over a striped electrode, the electrode is discharged and another in the forward direction is charged to keep the movement. The electrostatic linear actuator (ESLAC) consists of rollers inserted between a C-shaped stator and a slider that displaces linearly. Silicon micromachining techniques such as lithography, PCVD, and etching were utilized to fabricate the plane wafer. Model actuators were realized on silicon wafers. The performance of the models is examined 相似文献
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This paper reports an innovative technique for rapid fabrication of ultraviolet-cured polymer microlens arrays based on soft roller stamping process. In this method, a soft roller with microlens array cavity is made by casting a pre-polymer of polydimethylsiloxane (PDMS) in a plastic master of microlens array. The plastic master is prepared using gas-assisted hot embossing of polycarbonate (PC) film over a silicon mold with micro-holes array. The microlens array cavity on the soft roller is filled with liquid UV curable polymer first. The roller rolls and stamps over the traveling transparent substrate. The microlens array pattern is formed. At the same time, the pattern on the substrate is cured by the UV light radiation while traveling through the rolling zone.In this study, a roller stamping facility with UV exposure capacity has been designed, constructed and tested. The replication quality, surface roughness and optical property of the replicated microlens arrays are measured, analyzed and proved satisfactory. This study demonstrates the potential of soft roller stamping for continuous rapid mass production. 相似文献
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Polymer solar cells are fabricated by a novel solution coating process, roller painting. The roller‐painted film – composed of poly(3‐hexylthiophene) (P3HT) and [6,6]‐phenyl‐C61‐butyric acid methyl ester (PCBM) – has a smoother surface than a spin‐coated film. Since the roller painting is accompanied by shear and normal stresses and is also a slow drying process, the process effectively induces crystallization of P3HT and PCBM. Both crystalline P3HT and PCBM in the roller‐painted active layer contribute to enhanced and balanced charge‐carrier mobility. Consequently, the roller‐painting process results in a higher power conversion efficiency (PCE) of 4.6%, as compared to that for spin coating (3.9%). Furthermore, annealing‐free polymer solar cells (PSCs) with high PCE are fabricated by the roller painting process with the addition of a small amount of octanedi‐1,8‐thiol. Since the addition of octanedi‐1,8‐thiol induces phase separation between P3HT and PCBM and the roller‐painting process induces crystallization of P3HT and PCBM, a PCE of roller‐painted PSCs of up to 3.8% is achieved without post‐annealing. A PCE of over 2.7% can also be achieved with 5 cm2 of active area without post‐annealing. 相似文献