Development of wear resistant and dry self-lubricating coatings on sintered steels from polymer-derived ceramics (PDCs)

该建议的主要目标是开发具有高耐磨性和硬度、自润滑性能和低摩擦系数的涂层。作为基材，使用了由项目合作伙伴UFSC在弗洛里亚诺波利斯专门开发的烧结金属基材。首次证明了等离子体辅助热解(PAP)是一种适合于以有机硅氮烷(HTTS)为成瓷粘结剂、TiSi2为活性填料的致密陶瓷复合材料的制备技术。与传统的热解和在PAP中使用样品作为阳极相比，放置在阴极结构中会产生致密的陶瓷材料，这是因为更多的反应条件导致活性填料向相关氮化物的转化增加和致密化。仍在运行的第二阶段的目的是将这一知识传授给项目合作伙伴UFSC，以便在金属衬底上产生致密和坚硬的涂层。第三阶段计划采用等离子体技术对金属基材进行表面改性，在金属基材表面沉积氮化铁层或钼等难熔金属，以提高金属基材的硬度和硅氮烷涂层的附着力。还计划使用TiB2和Ti5Si3作为活性填料。通过使用TiB2，预计在含氮等离子体气氛中处理期间，填料转化遵循与TiSi2相同的反应路径。TiB_2与氮离子反应生成适合作为干润滑剂的hBN，而钛与前驱体热解生成的无定形SiCN相反应生成硬质氮化物和碳氮化物。采用TiSi2作为活性填料，经PAP处理后生成大量未反应元素硅，对涂层的力学性能和耐磨性产生不利影响。通过使用Ti5Si3作为活性填料，我们期望在减少未反应的Si的数量的同时，增加硬的Ti(C，N)相的形成。此外，还需要改变PAP参数以提高活性填料的转化率，最终实现金属基片的烧结和涂层的陶瓷化在一个周期内同时进行。该方法应减少处理步骤和时间。在这个合作项目中，不仅将金属、陶瓷和聚合物等不同性质的材料结合在一起，还将结合不同知识领域合作伙伴的专业知识。这样的项目不可能由每个合作伙伴单独实现。联合研究应该能够迅速实现新产品的制造，这些产品能够通过减少摩擦来提高机械部件的寿命和能效。

The main objective of the proposal is the development of coatings with high wear resistance and hardness, self-lubricating properties and low friction coefficient. As substrates, sintered metal substrates specifically developed by the project partner UFSC in Florianopolis are used. As described in our report we demonstrated for the first time that the novel process of plasma assisted pyrolysis (PAP) is a suitable technology for the development of dense ceramic composites based on a polyorganosilazane (HTTS) as ceramic forming binder and TiSi2 as active filler. In contrast to conventional pyrolysis and using the sample as anode in the PAP the placing in cathode configuration leads to a dense ceramic material, due to the more reactive conditions which result in an increased conversion of the active filler to the related nitrides and to a densification. Aim of the still running 2. period is to transfer this knowledge to generate dense and hard coatings on the metal substrates from the project partner UFSC. For the 3rd project phase it is planned to apply the plasma process to modify the surfaces of the metal substrates by depositing iron nitride layer or refractory metals like molybdenum to improve the hardness of the metal substrates and the adhesion of the silazane coatings. It is also planned to use TiB2 and Ti5Si3 as active fillers. By using TiB2 it is expected that the filler conversion follows the same reaction path like TiSi2 during treatment in the nitrogen containing plasma atmosphere. The reaction of TiB2 with nitrogen ions should lead to the formation of hBN which is suitable as dry-lubricating agent, whereas titanium forms hard nitrides and carbonitrides because of the reaction with the amorphous SiCN phase resulting from precursor pyrolysis. By employing TiSi2 as active filler a remarkable amount of unreacted elemental Si was formed after PAP treatment which could influence the mechanical properties and the wear resistance of the coatings adversely. By using Ti5Si3 as active filler we expect an increased formation of hard Ti(C,N) phases while the amount of unreacted Si is reduced. Additionally it is necessary to vary the PAP parameters to improve the conversion of the active fillers, and finally to enable the sintering of the metallic substrates and the ceramization of the coatings in one cycle simultaneously. The methodology should lead to a reduction in the processing steps and time. In this cooperation project, not only materials with different natures like metals, ceramics and polymers are going to be combined, but also the expertise of the partners in different knowledge fields. The realization of such project by each of the partners individually is not possible. The joint research should quickly enable the manufacturing of new products, which are able to increase the lifetime of mechanical parts and their energy efficiency through the reduction of friction.