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

该提案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。作为基板，使用由项目合作伙伴弗洛里亚诺波利斯的UFSC专门开发的烧结金属基板。正如我们的报告中所描述的，我们首次证明了等离子体辅助热解（PAP）的新工艺是一种合适的技术，用于开发基于聚有机硅氮烷（HTTS）作为陶瓷成型粘合剂和TiSi2作为活性填料的致密陶瓷复合材料。与传统的热解和在PAP中使用样品作为阳极相比，放置在阴极配置中导致致密的陶瓷材料，这是由于更具反应性的条件导致活性填料向相关氮化物的转化增加并导致致密化。目标是仍然运行2.项目合作伙伴UFSC将这些知识用于在金属基材上生成致密和坚硬的涂层。对于第三个项目阶段，计划应用等离子体工艺，通过沉积氮化铁层或钼等难熔金属来改性金属基材的表面，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TiB 2，预期填料转化遵循与在含氮等离子体气氛中处理期间的TiSi 2相同的反应路径。TiB 2与氮离子的反应应导致形成适合作为干润滑剂的hBN，而钛由于与由前体热解产生的无定形SiCN相反应而形成硬氮化物和碳氮化物。采用TiSi_2作为活性填料时，PAP处理后会形成大量未反应的元素Si，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，我们预期硬质Ti（C，N）相的形成增加，而未反应的Si的量减少。此外，有必要改变PAP参数以提高活性填料的转化率，并最终能够在一个循环中同时烧结金属基材和陶瓷化涂层。该方法应导致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，还将结合合作伙伴在不同知识领域的专业知识。由每个合作伙伴单独实现这样的项目是不可能的。联合研究应能迅速实现新产品的制造，这些新产品能够通过减少摩擦来延长机械部件的使用寿命和能源效率。

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.