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推导出了送粉激光熔覆覆盖率的计算方程 ,利用金相法检测了熔覆层宏观参数并结合相关的物理参数 ,计算了激光熔覆的送粉有效利用系数和激光熔覆覆盖率。另外 ,系统分析了扫描速度和送粉速率对覆盖率的影响。结果表明 :覆盖率随扫描速度的提高而降低 ;随送粉速率的加大而提高 相似文献
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针对激光熔覆AlCoCrFeNiTi合金的成形质量问题,探索工艺参数对稀释率、高宽比和熔覆面积的影响规律,实现熔覆成形质量的预测与优化。采用响应面法建立激光功率、扫描速度、送粉电压与稀释率、高宽比和熔覆面积的数学模型,通过NSGA-Ⅱ遗传算法进行多目标优化。试验结果表明,最优工艺参数为激光功率1 770.60 W,扫描速度5.96 mm/s,送粉电压为23.26 V,稀释率、高宽比、熔覆面积的误差分别为6.69%、9.27%、11.96%。稀释率随着激光功率和扫描速度的增大而增大,送粉电压则相反;高宽比及熔覆面积均随着扫描速度增大而减小,送粉电压则相反。该研究结果能为高熵合金熔覆层形貌的预测和控制提供理论依据。 相似文献
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推导出了送粉激光熔覆覆盖率的计算方程,利用金相法检测了熔覆层宏观参数并结合相关的物理参数,计算了激光熔覆的送粉有效利用系数和激光熔覆覆盖率。另外,系统分析了扫描速度和送粉速率对覆盖率的影响。结果表明:覆盖率随扫描速度的提高而降低;随送粉速率的加在而提高。 相似文献
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以机械设备摩擦损伤区域的修复与再制造为背景,选取汽轮机叶片用料17-4PH马氏体沉淀硬化不锈钢作为研究对象,采用激光熔覆技术进行表面创新修复,在17-4PH不锈钢表面以不同的送粉量熔覆Ni和WC合金粉末,观察并测试熔覆层、熔覆层与基材交界处和基材的微观结构和成分分布,测试熔覆层的力学性能,在试验过程中分析熔覆过程中送粉量对涂层品质的直接影响。试验结果表明:在相同的激光功率(1 250 W)和送粉速率(10 mm/s)下,随着送粉量的增大,熔覆层的显微硬度增大。 相似文献
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为了确定在ZG06Cr13Ni4Mo不锈钢板上激光熔覆In625镍基合金粉末的最佳生产工艺参数,采用响应曲面分析法设计并开展一系列的激光熔覆参数实验,并利用Desigh-Expert软件中Response Surface模块对最终数据进行方差定量分析。通过金相显微镜对多道搭接熔覆试样的表面形态和横截面组织进行了观察和定性分析,从而确定熔覆工艺的最佳参数组合。结果表明,在维持送粉量不变的条件下,熔覆层高度对激光功率与扫描速度的响应都比较明显;熔覆工艺的最佳参数组合为激光功率2000 W,送粉量84 g·min?1,扫描速度5 mm·s?1,在此参数下获得的熔覆试样具有高质量的熔覆层,无气孔和裂纹,且表面光滑。 相似文献
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综述了近几年激光熔覆技术的研究进展,包括了激光熔覆涂层材料、激光熔覆层组织、以及主要工艺参数对熔覆层的影响等,对激光熔覆涂层存在的主要问题进行了归纳总结。在此基础上指出了激光熔覆技术的主要发展方向。 相似文献
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The latest progress and research status of laser cladding ceramic coating was summarized. Technique characteristics and influence factors of laser cladding technique were introduced. Laser cladding technique includes the mixing method and laser irradiation. The mixing method can be classified as pre-coating method and synchronization method. The technique parameters include size of facula, scanning speed, cladding sector and times, adding quantity of powder, thickness of coating and quantity of joint coating. The results show that proper technique parameters can be controlled in order to acquire high quality laser cladding coating. Strengthened effect mechanism of rare earth additive is concluded, and the main effects of rare earth additive are micro-alloying, purifying boundary, fining crystal grains, improving crystal boundary, restraining columnar crystal growing. The development of laser cladding ceramic coating research was discussed. 相似文献
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Effect of Y2O3 Content on Microstructure of Gradient Bioceramic Composite Coating Produced by Wide-Band Laser Cladding 总被引:2,自引:0,他引:2
Hydroxyapatite (HA) ,a kind of bioactive materi-al , has wide application prospect in hard tissue re-placemen and repairment due to its si milar chemicalcomposition and crystallographic structure to that ofbone mineral[1 ,2]. Since HA has lowstrength (50 … 相似文献
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Effect of rare earth elements and their oxides on tribo-mechanical performance of laser claddings: A review 总被引:1,自引:0,他引:1
《中国稀土学报(英文版)》2016,(6)
Laser cladding is a promising photon-based surface engineering technique broadly utilized for fabricating harder and wear resistant composite coatings. In spite of excellent properties, the practical applications of laser claddings are relatively restricted when compared with well-established coating techniques because of their inherent defects identified as cracks, pores and inclusions. Substantial evidence suggests that the incorporation of an appropriate amount of rare earth in laser claddings can remarkably prevent these defects. Additionally, the presence of rare earth in laser claddings can notably enhance tribo-mechanical properties such as surface hardness, modulus of elasticity, fracture toughness, friction coefficient and wear rate. In this literature review, the effect of rare earth in reducing dilution and cracks susceptibility of laser claddings in addition to microstructural refinement attained was examined. Mechanical and tribological properties of these claddings along with their underlying mechanism were discussed in detail. Finally, this article summarizes current applications of laser claddings based on rare earth and was concluded with future research directions. 相似文献
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综述了激光熔覆陶瓷增强金属基复合涂层的研究现状,分析了碳化物、氧化物、硅化物等对激光熔覆涂层性能的影响。 相似文献
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紫铜上激光熔覆镍基自熔合金组织和性能研究 总被引:2,自引:0,他引:2
采用万瓦横流CO2激光器在紫铜表面熔覆镍基自熔合金熔敷层,并采用SEM、XRD、OM和显微维氏硬度计进行组织结构和硬度分析。结果表明:在紫铜表面完全可采用激光熔覆的方法制备镍基自熔合金的熔覆层,熔覆层与铜基体形成冶金结合,组织致密、晶粒细小、无裂纹、孔隙夹杂等缺陷,熔敷层内具有等轴晶、树枝晶及胞状晶等不同结构,并有WC、W2C、Ni3B等强化相颗粒。同时,与采用超音速火焰喷涂(HVAF)涂层进行对比,结果表明激光熔覆层硬度虽然低于喷涂涂层,但磨擦系数小,耐磨损性能有明显的提高。 相似文献
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The cracking morphology of the hardfacing specimens taken from steel 5CrNiMo was observed. Meanwhile, the residual stress fields were measured and simulated. Based on experiment mentioned above, the improved structure and modified inclusion in hardfacing metal with rare earth (RE) oxide were analyzed. The results show that, the hardfacing crack is initiated from the coarse dendritic crystal grain boundary, inclusions and coarse austenite grain boundary in the HAZ and propagated by the residual stress existing in the center of the hardfacing metal and HAZ. The primary columnar grain structure can be refined by adding RE oxide in the coating of the electrode. The inclusion in the hardfacing metal can be modified as well. Meanwhile, if the martensite transformation temperature is decreased, the largest value of the residual tensile stress in the dangerous region can be reduced. 相似文献
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稀土氧化物对连铸保护渣结晶温度的影响 总被引:4,自引:0,他引:4
为了解决稀土钢浇注时因稀土氧化物进入保护渣导致保护渣性能改变的问题,用热重一差热分析仪系统地观测了稀土氧化物对不同碱度及BaO、B2O3和Li2O含量的保护渣结晶温度的影响。结果表明,稀土氧化物对保护渣结晶温度影响显著,特别是稀土氧化物从零增至5%时最为明显。随着稀土氧化物含量的继续增加,保护渣结晶温度缓慢升高。低碱度可以抑制保护渣中稀土矿物初生晶核的析出;BaO有利于稀土氧化物在保护渣中的溶解和扩散;B2O3基本上可消除稀土氧化物引起的保护渣结晶温度升高的不良影响;Li2O可阻止高熔点结晶相的析出,降低含稀土氧化物保护渣的结晶温度。 相似文献
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Preparation and Corrosion Resistance of Rare Earth Ceramic Film on AZ91 Magnesium Alloy 总被引:1,自引:0,他引:1
With the purpose of improving corrosion resistance and solving environmental pollution caused by traditional protective technique, rare earth ceramic film on AZ91 magnesium alloy was prepared by dip coating process, and technical parameters of preparation were defmed. Microstructure and composition of the film were studied and corrosion resistance was evaluated as well. The results show that rare earth ceramic film is uniform,dense, with strong cohesion and intact coverage. The film is mainly made up of CeO2 and MgCeO3. The results of corrosion experiments approve that the film acts as a barrier to isolate the contact of the substrate with corrosion media and decreas corrosion rate. Polarization curve of the coated sample shiftes to positive potential obvito 2.7 × 104 Ω. These facts indicate that rare earth ceramic film could effectively improve corrosion resistance of AZ91 magnesium alloy. 相似文献
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Effect of Laser Power on Microstructure and Wear Resistance of WCP/Ni Cermet Coating 总被引:1,自引:0,他引:1
Laser cladding nickel-based alloy coating (Ni60) and nickel-based composite coating doped with WC particles by 35 % (WCp/Ni) were produced on the low-carbon steel substrate by CO2 continuous wave laser with power of 5 kW using the injected powder technique. The effect of laser power on microstructure and wear resistance of laser cladding WCp/Ni cermet coating was investigated. The WCp/Ni alloy coating with evenly distributed WC ceramic phases and the better bond with the substrate alloy was obtained at a power of 2.2 kW. Diffusion solution reaction happened between WC particles and the substrate alloy during laser cladding, and led to the formation of block rich-tungsten carbide on the edges of the WC particles, especially at higher power. The WCp/Ni alloy coating consists of the undissolved WC particles, the block or dendritic rich-tungsten carbide, the bar-like rich-chromium carbide, and dendrite solid solution and eutectic structure among the carbides. Microhardness and wear resistance of the WCp/Ni coating at different powers were much higher or better than those of Ni60 alloy coating, and the best results were obtained at power of 2.2 kW. 相似文献
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讨论了晶粒细化、热处理制度、合金元素及稀土添加剂对6063铝合金导热性能的影响,在分析实验数据的基础上,阐述了各影响因素的作用机制。结果表明良好的铸态组织、适宜的时效制度、合理的合金元素配比与适量稀土处理剂均能不同程度的提高材料的导热系数。 相似文献