激光表面微织构工艺试验及应用研究

在声光调Q二级管泵浦固体光源Nd:YAG激光器基础上,采用"单脉冲同点间隔多次"激光微加工工艺,对45#钢试样表面进行激光微织构加工。分析了离焦量、泵浦电流、重复频率及重复次数对微织构形貌的影响规律。工艺试验表明,微凹腔的直径和深度随着泵浦电流的增大而增大,随着重复频率的增加呈减小的趋势,微凹腔深度随脉冲次数的增加呈近似线性增加,而微凹腔直径呈缓慢减小趋势。通过对某型号四缸汽油机的台架性能试验研究,表明与传统平顶机械珩磨相比,采用激光珩磨技术的汽油机机油耗要比原机降低56%,燃油耗降低1.94%~4.5%。     

ZCuSn10Zn2铜合金激光表面微造型工艺试验

为加工出符合摩擦学性能要求的ZCu Sn10Zn2铜合金表面微造型形貌,采用激光微造型技术对ZCu Sn10Zn2铜合金表面进行网格图案化处理,利用共聚焦显微镜和X射线应力测定仪对加工后的试样进行表面形貌表征及残余应力测试。考察不同工艺参数对材料耐磨损性能的影响。结果表明:激光微造型后材料的表面粗糙度随激光功率的增大先减小后增大,微沟槽的深度随激光功率的增大先增大后减小,微沟槽的宽度与工作电流成正相关性,但随电流的增大趋于饱和。表面残余应力随工作电流增大趋势明显,微造型后,表层存在较大的残余拉应力。试验结果对深入探索ZCu Sn10Zn2铜合金的激光微造型工艺提供了一定的数据基础。     

激光造型技术在摩擦副表面处理中的应用

摩擦副表面的微细形貌深刻影响着摩擦副的摩擦学性能,因而人们利用各种加工方法对摩擦副进行表面处理以达到所需的摩擦学性能,激光表面造型技术以其诸多的优点而被认为是摩擦副表面处理的理想手段.首先阐述了激光表面造型技术的原理及其减磨机理.介绍了激光表面造型专用设备的基本组成及其控制原理,接着详细论述了激光表面造型技术在重要摩擦副处理中的应用及取得的效果,最后提出了激光表面造型技术的发展和应用前景.     

TC11钛合金表面微凹坑织构皮秒激光加工工艺

目的研究皮秒激光加工工艺参数对微凹坑形貌的影响规律。方法采用FSLAB-50-05激光器搭建的激光器平台对TC11钛合金工艺试样进行表面微加工,通过WYKO—NT1100型表面三维形貌测试仪获得表面微凹坑织构形貌,分别记录微加工后的二维与三维形貌图,应用单因素法分析激光重复频率、激光持续时间和激光功率对微凹坑形貌的影响规律。结果在激光功率为10 W、激光持续时间为0.12 ms的前提下,当激光重复频率由50 k Hz增加到250 k Hz时,微凹坑的直径和深度均呈现出先增大后减小的趋势;在激光功率为10 W、激光重复频率为300 k Hz的前提下,当激光持续时间由0.02 ms增加到0.10 ms时,微凹坑直径和深度均随着激光持续时间的增加而变大;在激光重复频率为300 k Hz、激光持续时间为0.12 ms的前提下,当激光功率由4 W提升至12 W时,微凹坑的深度随着激光功率的增大而增大,而宽度先增大后减小。结论皮秒激光微凹坑织构较佳的工艺参数范围为:激光重复频率150~200 k Hz,激光持续时间0.04~0.06 ms,激光功率8~10 W。     

Incoloy800H合金表面激光熔覆SiC的显微组织分析

对Ｉｎｃｏｌｏｙ８００Ｈ合金表面激光熔覆ＳｉＣ后的显微组织进行了分析。熔覆层通过柱状晶过渡区与基体牢固结合，熔覆层的维氏硬度有较大提高。ＳｉＣ颗粒在熔覆处理中发生了部分分解，形成大量弥散分布的粒状Ｍ７Ｃ３共晶碳化物。另外熔覆处理不致了高密度位错亚结构的产生。     

激光加工工艺参数对Invar 36合金表面微织构质量的影响

目的 提高微织构的加工效率和加工质量,为改善Invar 36合金的表面性能及微织构加工工艺参数提供理论依据。方法 为了保证该研究的合理性和可行性,采用光纤激光加工技术并结合正交试验法研究了激光功率,激光频率,激光扫描速度和扫描次数4种不同加工参数对微织构凹槽表面形貌结构尺寸及加工质量的影响,并通过摩擦学试验方法测试了其对应的摩擦学性能。最后,通过三维形貌测试仪和扫描电子显微镜对微织构加工结果进行测量表征。结果 微织构凹槽的加工质量与激光扫描次数和扫描速度的关系更大,随着激光扫描次数的增加,微织构的深度明显增加,但是其宽度逐渐减少。当扫描次数在5~15次时,随着扫描次数的增加,微织构表面及边缘熔融物不规则凸起逐渐平整。激光扫描速度与微织构凹槽的宽度成正比,但是与微织构凹槽的深度及边缘不规则凸起的高度成反比关系。此外,当激光扫描次数为15次,激光扫描速率为400~500 μm/s时,加工的微织构表面粗糙度更低,且根据摩擦试验结果,发现该条件下加工的微织构摩擦副的减摩耐磨效果更佳。结论 激光扫描次数和激光扫描速度是影响凹槽型微织构加工质量和表面性能的关键因素,试验结果表明在适当的激光加工工艺参数下(P=0.04 W,f=20 kHz,v=500 μm/s,n=15)微织构凹槽具有较高的加工质量,从而有效改善Invar 36合金的摩擦学性能,对未来进一步提高Invar 36合金的表面性能及加工质量具有一定的指导意义。     

40Cr激光表面强化工艺的研究

为改善40Cr钢表面硬度的不足,采用CO2激光器对40Cr钢表面进行激光表面强化处理.分析了金相组织、显微硬度,得到了约0.7mm的硬化层,表面强化层硬度明显提高.试验结果表明:采用激光表面强化技术可以通过细化晶粒提高材料表面的硬度.     

气门摇臂激光表面合金化工艺研究

采用正交试验 ,对激光表面合金化工艺参数进行了优化 ,分析了各工艺参数对气门摇臂合金化层质量的影响。研究表明 ,激光功率、扫描速度、离焦量和合金化粉涂层厚度等工艺参数对气门摇臂的合金化层厚度、搭接情况和表面状况等质量指标的影响不同 ;使用优化的激光工艺参数 ,对体积小、形状复杂的发动机气门摇臂工作圆弧面进行了激光表面合金化处理 ,获得的合金化层搭接较好 ,精磨后厚度在 0 4 0～ 0 6 0mm范围 ,表面硬度 >78HRA。     

激光造型技术综述

对激光造型技术的优点、应用价值、加工机理等作了简单阐述,另外就该技术的发展历史和国外的研究状况作了具体介绍,之后对国内的研究情况作了归纳性介绍。根据目前激光造型技术的相关研究,提出激光造型技术今后的研究方向,并展望了未来的应用前景。     

轧辊表面光纤激光毛化工艺研究

利用光纤激光柔性工作站对轧辊表面进行毛化,研究了激光射出头姿态、侧吹角对毛化点形貌、毛化后轧辊表面粗糙度的影响,分析了其影响规律,总结出最佳毛化工艺。结果表明,12点位置和3点位置在特定侧吹角度时,毛化点分布相对独立,凸台金属分布集中,无点与点搭接现象,毛化点形貌满足要求。12点位置和9点位置各侧吹角度下的毛化表面粗糙度均满足要求。综合对毛化点形貌和毛化后轧辊表面粗糙度要求,12点位置的毛化效果优于3点位置。研究结果已应用于实际生产。     

光纤激光毛化机器人系统

光纤激光作为第三代激光技术的代表,具有其他激光器无可比拟的技术优越性和广阔的应用发展空间,将会逐步取代全球大部分高功率CO2激光器和绝大部分YAG激光器。利用光纤激光器的优点,集成开发了第五代全新的光纤激光机器人毛化系统,系统以光纤激光器为载体,协同机器人及其他设备来完成轧辊毛化作业。光纤激光毛化柔性工作站与传统的CO2激光毛化设备相比取得了多项重大突破,如系统采用普通机床代替昂贵的磨床实现毛化功能,不仅节约大量的设备投资费用,并大幅度提高生产效率;系统对轧辊旋转时的轴向跳动容忍度大,毛化速度大幅度提高;光纤激光毛化技术可实现毛化点形貌的任意设计以及毛化点的有序、无序排列;毛化成本大幅度降低,没有三废,是一种绿色制造技术。     

轧辊光纤激光无序毛化技术:无序毛化的应用(下篇)

在连轧机、平整机、光整机上对光纤激光无序毛化轧辊与电火花毛化轧辊的过钢量,粗糙度R_a和R_(pc)值随过钢量的变化进行了对比;同时,对光纤激光无序毛化轧辊R_a=2.0~5.0μm范围内与R_(pc)值的关联情况进行了研究。结果表明:光纤激光无序毛化轧辊适用于连轧、平整、光整等工艺,其R_(pc)值高于电火花毛化辊,且R_a与R_(pc)的关联度较弱。     

拉深模激光毛化工艺参数实验研究

为改善拉深模摩擦和润滑条件,提高其使用寿命,提出使用激光毛化技术对其表面进行造型强化。通过实验对影响激光毛化效果的主要工艺参数进行研究,得到拉深模激光毛化的合适工艺参数范围,为拉深模激光毛化表面摩擦性能研究及毛化点尺寸优化奠定基础。     

Effect of EDT surface texturing on tribological behavior of aluminum sheet

Surface texturing, which fabricates micro dimples or micro channels on the surface of parts, is a growing technique for improving tribological characteristics of materials. Currently, electrical discharge texturing (EDT) technique, one surface texturing method suitable for mass production, is being used to texture aluminum sheets for the applications in automotive industry. It has been widely accepted in industry that EDT improves the forming behavior of aluminum sheets due to better friction behavior. However, how the textures on the surface of sheet metal change the friction behavior has not been investigated. In this paper, the influence of EDT on the friction behavior of aluminum automotive sheet at different contact pressures and sliding speeds is investigated based on both experimental studies and numerical simulations. To fully investigate the tribological behaviors, a flat-on-flat friction test device was built and a numerical code based on mixed lubrication theory was developed. It was found that EDT texturing can reduce the friction coefficient of contacting pair at high contact pressure, however, increase friction coefficient at low contact pressure. Numerical simulations confirmed this finding. Furthermore, the model provides valuable information for the prediction of friction behavior of EDT sheets and helps to optimize processing parameters for various forming processes using EDT aluminum sheets.     

Sliding wear characteristics of solid lubricant coating on titanium alloy surface modified by laser texturing and ternary hard coatings

Titanium alloys are poor in wear resistance and it is not suitable under sliding conditions even with lubrication because of its severe adhesive wear tendency. The surface modifications through texturing and surface coating were used to enhance the surface properties of the titanium alloy substrate. Hard and wear resistant coatings such as TiAlN and AlCrN were applied over textured titanium alloy surfaces with chromium as interlayer. To improve the friction and wear resisting performance of hard coatings further, solid lubricant, molybdenum disulphide (MoS2), was deposited on dimples made over hard coatings. Unidirectional sliding wear tests were performed with pin on disc contact geometry, to evaluate the tribological performance of coated substrates. The tests were performed under three different normal loads for a period of 40 min at sliding velocity of 2 m/s. The tribological behaviours of multi-layer coatings such as coating structure, friction coefficient and specific wear rate were investigated and analyzed. The lower friction coefficient of approximately 0.1 was found at the early sliding stage, which reduces the material transfer and increases the wear life. Although, the friction coefficient increased to high values after MoS₂ coating was partially removed, substrate was still protected against wear by underlying hard composite layer.     

On the influence of different superficial laser texturing on the deposition of powders through cold spray process

Cold spray is a technique allowing the deposition of metallic powders on several different substrates. The deposition process is ruled by different factors, among these, of particular interest are the superficial roughness and texturing of the substrate. The aim of this research was to study the influence of different superficial texturing on the deposition process of aluminium powders on an AA 2024 T3 plate. Samples with different superficial texturing were produced by laser engraving through a Yb:YAG fibre laser, varying the laser treatment parameters. Aiming to highlight the influence of the laser treatment, the deposition process was carried out on all the samples under the same spraying condition. The cross-section of the interface between the substrate and the coating and the microstructure of the coating itself were observed to study the influence of the superficial texturing on the coating formation. It was found that the superficial texturing influences both the adhesion mechanism and the microstructure of the coating.     

磁控溅射SiC薄膜表面形貌演化行为研究

采用射频磁控溅射法在石英玻璃基底上沉积SiC薄膜.用扫描电子显微镜(SEM)和原子力显微镜( AFM)观察薄膜的表面形貌,利用粗糙度和颗粒度大小对薄膜表面形貌动态演化进行量化表征.结果表明:在100～175 W溅射功率范围内,1 000℃高温真空退火处理能明显减小SiC薄膜表面粗糙度,膜层表面更为平滑,颗粒大小更为均匀...     

冷轧辊毛化技术的对比研究

系统分析了几种国内外正在使用或试验研究的冷轧辊毛化技术，并依据其加工特性，从毛化轧辊的表面粗糙度、峰值密度、形貌传递特性、环境污染及设备运行成本等方面进行了较为深入的比较研究。在分析比较的基础上，提出了冷轧辊毛化技术的研究方向及发展趋势。