共查询到20条相似文献,搜索用时 78 毫秒
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用HGL-6000型横流CO2激光器在316L不锈钢表面熔覆Ni-WC涂层。采用金相显微镜观察熔覆层组织形貌;利用显微硬度计和电化学工作站研究了不同激光功率对熔覆层硬度及耐蚀性的影响。结果表明,熔覆层组织主要为树枝晶及共晶组织自表面向内部逐渐粗化;随激光功率增加,熔覆层组织先细小后变得粗大,当激光功率为3500 W时,组织最细小;随功率增加,熔覆层硬度降低,且自表面至结合处均呈下降趋势,当激光功率为2500 W时,熔覆层硬度(573HV1)最高,为基体的3.3倍,功率为3500 W时,熔覆层硬度为基体的2.2倍;随功率增加,熔覆层耐蚀性先增强后减弱,功率为3500 W的熔覆层耐蚀性优于其它功率的熔覆层且与316L不锈钢耐蚀性相当。 相似文献
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《热加工工艺》2017,(2)
利用激光熔覆技术在20CrNi2MoA钢表面制备铁基合金涂层。研究了激光功率对熔覆层显微组织、显微硬度的影响,分析了熔覆层和基体的摩擦磨损性能。结果表明:熔覆层组织由内及表依次为平面晶-胞状晶-树枝晶-等轴晶,无裂纹、气孔等缺陷,与基体呈良好的冶金结合。在一定功率范围内,激光功率增加使得枝晶尺寸增大以及显微硬度下降。在相同磨损参数下,激光功率为2.5、2.8 kW时熔覆层磨损量为7.35×10~(-3)mm~3和1.401×10~(-2)mm~3,相对耐磨性为基体的10.3倍和5.42倍,稳定磨损阶段熔覆层摩擦系数在0.24和0.26左右,而基体稳定在0.35左右。 相似文献
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45# 钢表面激光熔覆自熔性镍基碳化钨粉末 总被引:2,自引:2,他引:0
目的提高45#钢的表面性能。方法利用IPG光纤激光加工系统,采用不同的工艺参数在45#钢表面激光熔覆自熔性镍基碳化钨粉末,对熔覆层的宏观表面(平整度、表面硬度、裂纹情况)及金相组织、显微硬度分布进行对比分析。结果在激光功率为1200 W、扫描速度为2 mm/s、送粉电压为7 V时,获得的熔覆层宏观表面相对平整光滑,平均洛氏硬度约是基体的2.5倍。由微观组织分析得知,熔覆层及界面处无裂纹、气孔等缺陷,熔覆层中上部组织晶粒细小,沿熔覆层与基体交界处向外,晶粒呈现柱状晶及等轴晶,组织性能良好,基体与熔覆层间冶金结合比较牢固。熔覆层显微硬度分布比较均匀,并且与基体相比提高了约1.5倍。结论 45#钢表面机械性能得到提升,在其表面激光熔覆自熔性镍基碳化钨粉末具有可行性和研究价值。 相似文献
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钛合金表面激光熔覆Ti/Ni+Si3N4/ZrO2复合涂层组织与性能研究 总被引:1,自引:1,他引:0
目的 提高TA15合金的表面硬度,改善其耐磨性能.方法 以Ti/Ni+Si3 N4/ZrO2混合粉末为原料,利用激光熔覆技术,在TA15钛合金表面制备出以ZrO2颗粒和原位生成Ti5 Si3、TiN为增强相,以金属化合物TiNi、Ti2 Ni为基体的复合涂层.采用X射线衍射仪、扫描电镜及能谱仪等手段分析激光熔覆涂层的显微组织及磨损表面,通过硬度测试、摩擦磨损实验,对熔覆层的显微硬度和耐磨性进行评估.结果 熔覆层与基体形成了良好的冶金结合,熔覆层组织中TiNi和Ti2 Ni金属化合物基体上弥散分布着Ti5 Si3、TiN树枝晶和ZrO2颗粒;与不含ZrO2熔覆层相比,含有ZrO2熔覆层组织的晶粒得到细化;熔覆层中原位生成的TiN桥接在裂纹上,具有增韧的作用;熔覆层的显微硬度分布在835~1050 HV区间内,约为基体硬度的3倍左右;在干滑动摩擦磨损下,熔覆层的磨损量约为钛合金基体磨损量的1/6,其主要磨损机制为磨粒磨损和黏着磨损.结论 熔覆层中高硬度、耐磨陶瓷相和高韧性相的共同配合,显著提高了钛合金表面的硬度和耐磨性. 相似文献
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This study systematically investigates the effects of electrical resistance at the workpiece/electrode interface or electrode face on temperature dependent dynamic resistance during resistance spot welding (RSW). To evaluate temperature transport equations of mass, momentum, energy, species and magnetic field intensity in workpieces, the energy and magnetic equations in the electrode are solved. Contact resistances composed of constriction and film resistances are functions of hardness, temperature, electrode force and surface conditions. The results show that dynamic resistance is complicated due to different variations of film and constriction resistances with temperature at not only the faying surface but also the electrode face in the early stage, i.e. shorter than around 3 cycles. Dynamic resistance in this stage is fortunately insignificant to transport processes. When the power is off, dynamic resistance depends on competition between decreased bulk resistance and increased constriction resistance at the electrode face. Decreased constriction resistance at the electrode face reduces dynamic resistance and temperature. 相似文献
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Lü Jiaheng 《中国焊接》2007,16(4):42-46
The conventional methods of determining the dynamic resistance were mostly done by measuring the voltage and current at secondary side of transformer in resistance welding machines, in which the measuring set-up normally interferes with the movement of electrode, and the measuring precision is influenced by inductive noise caused by the high welding current. In this study, the dynamic resistance is determined by measuring the voltage at primary side and current at secondary side. This increases the accuracy of measurement because of higher signal-noise ratio, and allows to apply to in-process system without any wires connected to electrodes. 相似文献
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ZHAO Xuezeng Harbin Electric Machinery Plant.Harbin.China XING Jiandong.ZHOU Qingde Xi''''an Jiaotong University Xi''''an.China 《金属学报(英文版)》1992,5(12):489-495
A kinetic oxidation test and an isothermal oxidation test of Fe-Cr-Mn alloys containing0.50% to 2.69% C were carried out at 800 and 660℃ in atmosphere.A high temperatureabrasive wear test of the alloys was also done in a self-made wear tester.A study of themorphology of the oxide film and the element distribution in the subsurface indicated that:(1) with increasing C content of the alloys the amount of eutectic carbide increased andthe Mu content in the matrix participating in the oxidation process decreased,resultingin an increase of the oxidation resistance of the alloys:(2) The high temperature wearresistance of the alloys was closely related to the bulk hardness of the alloy and theamount of eutectic carbide.The increase in hardness of the alloys increased the hightemperature wear resisance.However,it must be emphasized that the wear resistanteffect of the carbides depends strongly on the support provided by the matrix. 相似文献
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使用氩弧熔覆制备不同碳含量Al0.5Co0.5NiCrFe高熵合金涂层,研究碳含量对Al0.5Co0.5NiCrFe高熵合金涂层组织与性能的影响。结果表明:碳加入后,高熵合金均由单一的FCC结构组成,并没有表征出其他物质,但根据高熵合金显微组织与能谱分析可以发现,高熵合金的枝晶间有碳铬化合物生成。高熵合金涂层的组织为典型的树枝晶结构,随着碳含量的增加,组织不断细化。随碳含量的增加,高熵合金涂层的硬度不断升高,当碳含量为4%时,硬度(383.2 HV0.5)和耐磨性均为最佳。随碳含量的不断增加,高熵合金的耐腐蚀性先增强后减弱,碳含量为2%时耐腐蚀性最佳。根据单位面积氧化增量,高熵合金的抗氧化性先增大后减小,当碳含量为2%时,抗氧化性最佳。 相似文献
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用氧—乙炔火焰对Ni-Cr-B-Si合金粉末等离子喷涂层进行了快速熔敷处理,结果表明,熔敷处理后的喷涂层的耐磨性和抗蚀性都有明显提高。 相似文献
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在介绍大电阻介质材料的制备及其在铝合金点焊中的应用方法的基础上,以LF21防锈铝合金点焊为例,经金相试样分析及扫描电镜分析,对比研究了在不同的焊接电流下,应用介质材料与未应用介质材料时的熔核形貌、缺陷及组织.结果表明,未加入大电阻介质的点焊熔核均出现气孔和未熔合缺陷;而加入大电阻介质,形核效果良好,有个别小气孔但未出现影响焊点力学性能的未熔合缺陷.此外,加入大电阻介质降低了对焊件表面质量的要求,从而提高了铝合金点焊质量的稳定性;可降低焊接电流,导致较低的电极温度从而提高了电极寿命. 相似文献