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激光熔覆技术在目前材料表面改性技术中应用较广泛。本文概述了激光熔覆技术及工艺方法,介绍了激光熔覆材料分类及特点,并展望了激光熔覆技术的发展前景。 相似文献
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针对冶金辊材的表面强化和再制造需求,采用激光熔覆技术在辊芯常用材料球墨铸铁表面制备了10V高速钢熔覆层,研究了半导体直接输出激光器的工艺对熔覆过程、熔覆层组织结构与性能等的影响.结果表明:半导体激光器能够显著提高熔覆效率,避免了脉冲激光熔覆时的开裂现象;获得的熔覆层连续平整、无裂纹气孔等宏观缺陷,与球墨铸铁基体呈冶金结合状态.熔覆层显微组织特征为片层状、块状、球形颗粒状等多种形貌的快速凝固组织,由α-Fe,VC,γ-Fe,Cr23C6和Fe V等组成.熔覆层内合金元素的成分宏观均匀分布,微区有V等偏析.熔覆层显微硬度达700 HV0. 1,是基体硬度320HV0. 1的2. 18倍.在优化的工艺条件下,熔覆层磨损量是磨损30 min时基体磨损量的43%,其磨损机制为磨粒磨损及摩擦磨损,750℃热震实验结果表明,熔覆层具有良好的耐磨抗力和热冲击抗力. 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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以激光熔覆铁基涂层为研究对象,在MM-P2屏显式摩擦磨损试验机上进行摩擦磨损对比实验,分析了不同工艺参数下熔覆层形貌及熔覆涂层后磨损量的变化关系.结果表明:熔覆涂层后的表面硬度均在62HRC以上,远高于基体的硬度;熔覆层的形貌和质量主要影响因素是扫描速度,激光功率次之,并在此基础上采用能量密度进行表征,能量密度为60 J/mm2左右时的耐磨性最好,其最佳组合工艺参数为激光功率3.2 kW左右、扫描速度300 mm/min左右.激光功率过高,扫描速度过快都会导致熔覆层耐磨性能下降. 相似文献
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表面碳含量、渗碳层深度、碳含量分布等因素对渗碳齿轮的性能影响重大。实验以两种不同渗碳工艺条件下的齿轮试样为研究对象,通过调整电子探针X射线显微分析仪工作条件,确定试样表面碳含量、渗碳层深度及碳含量分布状态的定量分析方法最佳条件为:加速电压10 kV,电子束流200 nA,束斑20 μm。同时,将两齿轮心部碳含量测试结果与火花源原子发射光谱仪测试结果进行了比对;将碳含量分布与硬度梯度进行了对照。结果表明:电子探针分析仪测试得到的心部碳含量值与火花源原子发射光谱仪测试值相近;电子探针测试的两试样碳元素分布趋势与在硬度计上检测的硬度梯度分布趋势相似。因此,利用电子探针X射线显微分析仪,不仅能准确测定渗碳层碳元素的含量,而且能直观地反映出各渗碳工艺条件下样件整个渗碳层碳元素含量的分布状况。 相似文献
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Sintered powder layers of a Ni-based brazing alloy were consolidated by scanned electron beam radiation to produce a continuous
fused coating. The surface of this coating was then remelted by laser and electron beams under differing conditions, resulting
in a variety of resolidification structures. Alloy BNi2 was chosen for these studies because it exhibits substantial hardening
on grain refinement and because it can be prepared in the glassy state relatively easily. Surface microhardness for BNi2 reaches
a maximum of about 1200 DPH at a cooling rate approaching 105 K/s. For higher quench rates, hardness decreases and ductility increases. As the cooling rate approaches 107 k/s, overlapping beam scans produce an extended amorphous surface. A solidification rate higher than that needed to produce
an amorphous structure in a single melt pass is necessary to avoid surface cracking or crystallization when overlapping melt
passes are employed.
formerly at the Naval Research Laboratory, Washington, DC 相似文献
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D. A. Romanov E. N. Goncharova E. A. Budovskikh V. E. Gromov Yu. F. Ivanov A. D. Teresov S. A. Kazimirov 《Russian Metallurgy (Metally)》2016,2016(11):1064-1071
The phase and elemental compositions of the surface layer in Hardox 450 steel after electroexplosive spraying of a TiC–Ni composite coating and subsequent irradiation by a submillisecond high-energy electron beam are studied by the methods of modern physical metallurgy. The electron-beam treatment conditions that result in the formation of dense surface layers having high luster and a submicrocrystalline structure based on titanium carbide and nickel are found. It is shown that electron-beam treatment of an electroexplosive coating performed under melting conditions leads to the formation of a homogeneous (in structure and concentration) surface layer. 相似文献
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Titanium alloy has been a successful implant material owing to its excellent ratio of strength to weight, toughness, and bio inert oxide surface. Significant progress has been made in improving the bioactivity of titanium alloy by coating its oxide surface with calcium phosphates. In the present study, in situ coating was reported on Ti6Al4V(TC4) surface with calcium phosphate (Ca P) bioceramics synthesized and synchronously cladded by laser beam. This coating was grown by first preplacing directly the raw powders, which contain 80% of CaHPO4·2H2O, 20% of CaCO3, and dram of rare earth (RE), on the TC4 surfaces, and then exposing the surfaces to the laser beam with a power density of 1273-1527 MW·m-2 and a scanning velocity of 105 m/s. The resultant coating was characterized using scanning electron microscopy (SEM), X ray diffraction (XRD), thermogravimetric analysis and Different thermal Scanning (TG DSC), and Energy Dispersive X ray Detection (EDX). The results show that these laser ceramics include hydroxyapatite (HA), tricalcium phosphate (TCP), Ca2P2O7, and other Ca P phases, and the interface between the coating and the TC4 substrate has tighter fixation, in which the chemical bonding is approved. These laser hybrid coatings are useful in enhancing the bioactivity of titanium alloy surfaces. 相似文献
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《中国稀土学报(英文版)》2020,38(6):683-688
Fe-based composite coatings were fabricated on 5 CrNiMo die steel by laser beam melting a precursor mixture of ferrotitanium,ferrochromium,ferromolybdenum,B4 C and Y_2 O_3 powders.Micro structure and properties of the coatings were studied by X-ray diffraction(XRD),scanning electron microscopy(SEM),energy-dispersive spectrometer(EDS),resistance furnace and high-temperature tribometer.The results show that(Ti,Mo)C particles with flower-like and(Ti,Mo)B_2 with block-like shapes are in situ formed during laser cladding.Volume faction of multiple ceramic particles increases with the increasing of Y_2 O_3.The cumulative oxidation mass of the coating with 2 wt% Y_2 O_3 is decreased by one-third than that of the coating without Y_2 O_3.The oxidation layer of the coating with Y_2 O_3 is getting smooth.Meanwhile,high temperature wear volume loss of the coating with 2 wt% Y_2 O_3 is about 40% that of the coating without Y_2 O_3.The coating with 2 wt% Y_2 O_3 shows a smoother wear scar and few flat grooves are observed after high temperature wear test. 相似文献
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热浸镀锌铝镁镀层因其具有更优异的切口保护性能和耐腐蚀性能等而被广泛应用于汽车和家电领域,而锌铝镁镀层钢板的耐蚀性与其物相组成密切相关。因此,为了更好地研究热浸镀低合金高强钢Zn-Al-Mg镀层表面与截面的微观组织与物相结构组成,利用聚焦离子束(FIB)对镀层截面进行了微区加工和精抛,制备出了平整光亮无应力的待观察面。首先利用扫描电镜(SEM)和能谱(EDS)初步分析了锌铝镁镀层表面与截面的微观组织形貌与成分,再利用电子背散射衍射技术(EBSD)菊池花样标定准确判定了锌铝镁镀层的物相结构与组成。研究表明,锌铝镁镀层表面与截面物相构成相同,均是由粗大枝晶状的初生富Zn相、相对细小鱼骨状或枝晶状的Zn-Mg二元共晶相和更为细小颗粒状或条状Zn-Mg-Al三元共晶相构成。另外还发现,在块状的初生富Zn相中均匀弥散分布着大量的纳米析出颗粒富Al相。经EBSD菊池花样标定准确判定了热浸镀锌铝镁镀层的物相结构,其中粗大枝晶状的初生富Zn相为具有密排六方结构的Zn相,相对细小鱼骨状或枝晶状的Zn-Mg二元共晶相为具有相同密排六方结构的Zn-MgZn2,更为细小颗粒状或条状Zn-Mg-Al三元共晶相为Zn-MgZn2-Al。另外,初生Zn相中析出的纳米级富Al相颗粒有效地提升了镀层的表面硬度。同时,在初生Zn相和共晶相的边缘均覆盖着一层MgZn2相,该相可以有效地延缓腐蚀进程。 相似文献
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