Synthesis and tribological investigation of carbon nanotube, onion-like carbon and nanodiamond reinforced nickel matrix composites

碳纳米管、洋葱状碳和纳米金刚石被认为是很有前途的金属基复合材料增强颗粒。这是因为它们具有出色的物理性能，如高强度、硬度、导电性和导热性，以及减少摩擦和磨损。本提案涉及碳纳米颗粒增强镍基复合材料的生产及其微观结构，化学和摩擦学特性。这将提供不同复合材料在干摩擦条件下摩擦学性能的直接比较。第一个里程碑将是优化粉末冶金制造参数，最好地适应每种增强材料。因此，必须实现和分析稳定且均匀的颗粒/溶剂分散体。随后的复合材料将在密度、微观结构、硬度、形貌、颗粒/基体分散和烧结后结构颗粒质量方面进行分析、比较和优化。第二个目标是通过进一步表征产生的磨损痕迹来解释和比较复合材料的摩擦学行为。这涉及到微观结构、氧化物形成和颗粒位移以及磨损速率和磨损机制。此外，将监测颗粒降解甚至石墨化。如果观察到，则引起变换的负载范围将是感兴趣的。因此，摩擦学行为，作为相对湿度和负载的函数，在所述转变之前和之后，将带来进一步的线索，作为管理mechanism.The下一步是预测的平均晶粒尺寸的镍基体的颗粒类型和体积分数的函数。一个随之而来的和显着的颗粒基质钉扎效应相关的颗粒和晶粒尺寸。为此，齐纳方程将采用实验微观结构表征，以适应相应的镍基复合材料。因此，平均晶粒尺寸和复合材料的磨损性能之间的直接相关性将是可能的。本目标的实现，最合适的颗粒可以在镍基复合材料的摩擦学应用中的青睐。目前的研究可能是在这一领域使用其他基质材料进行进一步科学工作的起点，因为据我们所知，没有这样的出版物比较了不同碳纳米颗粒作为同一金属系统中的增强相的摩擦学性能。

Carbon nanotubes, onion-like carbon and nanodiamonds are considered as highly promising reinforcement particles for metal matrix composites. This is justified by their outstanding physical properties like high strength, hardness, electrical and thermal conductivity as well as friction and wear reduction. The present proposal deals with the production of carbon-nanoparticle-reinforced nickel matrix composites and their microstructural, chemical and tribological characterisation. This will provide a direct comparison of the different composites concerning their tribological properties under dry friction.The first milestone will be to optimise the powder-metallurgical parameters of the fabrication, best adapted to each reinforcement. A stable and homogeneous particle/solvent dispersion must thus be achieved and analysed. The subsequent composites will be analysed, compared and optimised in terms of density, microstructure, hardness, topography, particle/matrix dispersion and post-sintering structural particle quality.The second objective consists in interpreting and comparing the tribological behaviour of the composites through further characterisation of the produced wear tracks. This involves the microstructure, oxide formation and particle displacement as well as the wear rate and wear mechanisms. Furthermore, particle degradation or even graphitisation will be surveilled. If observed, the load range responsible for the transformation will be of interest. Consequently, the tribological behaviour, as a function of the relative humidity and load, before and after said transformation will bring further clues as to the governing mechanisms.The next step is the prediction of the mean grain size of the nickel matrix as a function of particle type and volume fraction. A consequent and pronounced particle-matrix pinning effect correlates particle and grain size. For this purpose, the Zener equation will be adapted using experimental microstructural characterisation to fit the corresponding nickel matrix composite. Thus, a direct correlation between the mean grain size and the wear behaviour of the composites will be possible.The present objectives achieved, the most fitting particle can be favoured for tribological applications in nickel matrix composites. The presented study could be the starting grounds for further scientific work in this field using other matrix materials, since, to the best of our knowledge, no such publication compares the tribological properties of different carbon nanoparticles as reinforcement phases in the same metal system.