【摘要】 目的 获得一种既具有一定厚度又能保持优异性能的厚涂层，期望广泛用于机械设备零件的表面强化以及再制造。方法 采用反应等离子喷涂技术在42CrMo钢基材上制备不同Ti N含量的Ni60B-TiN复合涂层并对比其组织和性能，选取最优成分含量作为梯度涂层的工作层，从而确定成分梯度范围，并对梯度化设计的Ni60B-TiN梯度涂层与复合涂层进行了性能对比。利用XRD、SEM、EDS分析涂层物相组成和微观组织形貌，观察涂层磨损形貌，分析磨损行为。利用显微硬度计、摩擦磨损试验机测量涂层的显微硬度和耐磨性。采用三点弯曲试验和黏结试样拉伸法测量涂层的弹性模量和结合强度。结果 反应等离子喷涂技术制备的Ni60B-TiN涂层组织致密，没有未熔颗粒的存在，仅存在少量孔隙，涂层主要由Ni基合金相(γ-Ni、Cr_1.12Ni_2.88、FeNi₃)和Ti N相组成。30%TiN含量的涂层具有最佳的组织均匀性、最小的磨损痕迹宽度和磨损体积（0.68 mm³），耐磨性能最好，选其作为梯度涂层的工作层最佳。梯度化设计后的涂层应力得到有效缓解，弹性模量显著提高（72 GPa），结合强度较复合涂层高约1.7倍，提高了涂层的耐磨减摩性能。结论 采用成分梯度化设计可以获得较复合涂层更高弹性模量、结合强度和耐磨性的厚涂层。更多还原

【Abstract】 In this study, Ni60B-TiN composite coatings with different TiN contents were prepared on 42CrMo steel substrates by reactive plasma spraying technology. By using the formation mechanism of Ti N droplets generated by the combustion synthesis reaction of Ti powder with N₂ during the plasma spraying process and deposited and solidified simultaneously with Ni-based alloy, Ni60B-TiN composite coatings with well-bonded interphase and dense organization were obtained. Considering the demand for surface strengthening and remanufacturing of mechanical equipment parts in practical engineering applications, a composition gradient coating with a certain thickness（600 μm） and excellent performance was designed and prepared based on the study of composite coatings. By comparing the microstructure and mechanical properties of Ni60B-TiN composite coatings with different TiN contents, the optimum composition content was selected as the working layer of the composition gradient coating, and the properties of the composite coating and the composition gradient coating were compared and analyzed.X-ray diffraction（XRD） was used to analyse the physical phase of the coating. Scanning electron microscopy（SEM） and an equipped energy spectrometer（EDS） were applied to observe and analyse the microstructure of the coating and the constituent elements in specific areas, the wear behaviour of the coating by observing the wear morphology and the toughness of the coating by observing the fracture morphology. A microhardness tester was used to measure the microhardness of the coatings, randomly measuring 20 points and characterising them with a Weibull distribution to obtain data on the hardness of the coatings. The wear resistance of the coating was measured by friction and wear testing machine（a GCr15 steel ball with a radius of 4 mm as a friction pair）, and the wear volume of the coating was estimated by a microprobe. A three-point bending test was used to measure the curve relationship between the loading and the displacement center of the coating specimen, and the elastic modulus of the coating was calculated based on the elastic modulus formula derived from the bending model. The bonding strength of the coating was calculated by using the bonding specimen tensile method and the corresponding formula.The results show that Ni60B-TiN composite coating is mainly composed of Ni-base alloy phase(γ-Ni, Cr_1.12Ni_2.88, FeNi₃)and TiN phase. The coating with 30wt.%TiN content has the best microstructure uniformity, the smallest wear trace width and wear volume（0.68 mm³）, and has optimal wear resistance. Therefore, the composition gradient of TiN content in Ni60B-TiN gradient coating is selected as 0wt.%, 5wt.%, 10wt.%, 15wt.%, 20wt.%, 25wt.%, 30wt.%. By comparing the properties of the composite coating and the composition gradient coating, it is found that the internal stress of the gradient coating is effectively alleviated, and the problem of poor bonding due to the mismatch of physical properties between the coating and the substrate is improved. The elastic modulus of the coating is significantly enhanced（72 GPa）, and the bonding strength is about 1.7 times higher than that of the composite coating, which improves the wear resistance and wear reduction performance of the coating. Ni60B-TiN composition gradient thick coating which can be widely used on the surface of mechanical parts has been successfully obtained.更多还原