Cu含量对激光选区熔化CoCrMoCu合金微观组织及表面摩擦磨损性能的影响

Effect of Cu Content on Microstructure and Tribological Properties of CoCrMo Alloy Fabricated by Selective Laser Melting

目的阐明不同Cu含量对激光选区熔化(Selective Laser Melting,SLM)制备的CoCrMoCu合金微观组织的影响及其在表面摩擦磨损和腐蚀性能使役行为方面的作用。方法采用CoCrMo合金粉和纯Cu粉通过行星球磨机进行机械混合,制备了Cu质量分数为2%、4%、6%的CoCrMo/Cu混合粉末,并通过SLM技术制备相应的试样。对不同Cu含量的SLM CoCrMoCu的相组成、微观结构、硬度、摩擦磨损和腐蚀性能进行检测和分析。结果Cu含量对SLM CoCrMoCu的相组成和微观组织没有明显影响,在不同Cu含量的试样中,试样的微观组织均主要为胞状等轴晶。在力学性能方面,随着Cu含量的升高,试样的硬度先提升后降低,在含2%Cu的情况下达到最大值(429.2HV0.2),在含6%Cu的情况下达到最小值(367.7HV0.2)。CoCrMoCu的摩擦因数和磨损率随着Cu含量的升高而降低,在4%时摩擦因数和磨损率达到最低(2.7×10^(-5)mm^(3)/(N·m)),摩擦磨损性能最好。随着Cu质量分数进一步增加到6%,由于硬度降低,磨损性能下降,试样表面出现沟壑,影响Cu自润滑层的附着,磨损机制由黏着磨损向磨粒磨损转变,导致摩擦因数和磨损率增加。在腐蚀性能方面,腐蚀电位随着Cu含量的升高而升高,而腐蚀电流随着Cu含量的升高呈现先下降后上升的趋势,在4%时达到最佳的腐蚀性能。结论Cu的引入在一定范围内(2%~4%)可以有效提高CoCrMoCu合金的硬度和腐蚀性能。结合Cu的自润滑效应和类钝化效应,实现CoCrMo合金耐磨性能和腐蚀性能的协同提升。

The work aims to investigate the effect of different Cu contents on the microstructure and surface friction and wear properties of CoCrMoCu alloy prepared by selective laser melting(SLM).In order to achieve this,CoCrMo alloy powder and pure Cu powder were mechanically mixed with a planetary ball mill to prepare CoCrMo/Cu mixed powders with Cu contents of 2wt.%,4wt.%,and 6wt.%respectively.The corresponding samples were then prepared by SLM technology,and their properties were tested and analyzed.The phase composition of the samples was first analyzed using X-ray diffraction(XRD).The results showed that the Cu content had no significant effect on the phase composition of the CoCrMoCu alloy prepared by SLM.In all the samples,the microstructure was mainly composed of cellular equiaxed grains.These results suggested that the addition of Cu did not significantly affect the microstructure of the CoCrMoCu alloy.The microstructure of the samples was further analyzed by scanning electron microscopy(SEM).The images showed that the CoCrMoCu alloys with different Cu contents had similar microstructures.The samples exhibited cellular equiaxed crystals,which were evenly distributed throughout the samples.This further confirmed that the addition of Cu did not significantly affect the microstructure of the CoCrMoCu alloy.The hardness of the samples was then tested with a Vickers hardness tester.The results showed that the hardness of the samples increased with the addition of Cu up to a certain point,and then decreased.The sample with 2wt.%Cu had the highest hardness of 429.2HV0.2,while the sample with 6wt.%Cu had the lowest hardness of 367.7HV0.2.These results suggested that the addition of Cu had a complex effect on the hardness of the CoCrMoCu alloy.The self-lubricating effect of Cu could enhance the hardness,but excessive Cu could decrease the hardness.Finally,the friction and wear properties of the samples were analyzed by wear friction tester.The results showed that the addition of Cu had a significant effect on the friction and wear properties of the CoCrMoCu alloy.The friction coefficient and wear rate decreased with the addition of Cu up to a certain point,and then increased.The sample with 4wt.%Cu had the lowest friction coefficient and wear rate,indicating the best friction and wear performance.The decrease in friction coefficient and wear rate was attributed to the self-lubricating effect of Cu.However,with further increase in Cu content,the friction coefficient and wear rate increased due to the decrease in hardness,and the wear mechanism changed from adhesive wear to abrasive wear.This study investigates the effect of different Cu contents on the microstructure,surface friction and wear properties of CoCrMoCu alloy prepared by SLM.The results show that the addition of Cu does not significantly affect the phase composition and microstructure of the CoCrMoCu alloy,but has a complex effect on the hardness as well as friction and wear properties.The sample with 4wt.%Cu exhibits the best friction and wear property,indicating that the Cu content is optimal for SLM CoCrMoCu alloys.