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Plasma-generated silicon oxide coatings of carbon fibres for improved bonding to mineral-based impregnation materials and concrete matrices
Cement & Concrete Composites ( IF 10.5 ) Pub Date : 2020-05-08 , DOI: 10.1016/j.cemconcomp.2020.103667
Jitong Zhao , Marco Liebscher , Albert Michel , Kai Schneider , Rüdiger Foest , Maik Fröhlich , Antje Quade , Viktor Mechtcherine

To improve its bonding behaviour with cementitious materials, the surface of carbon fibre (CF) yarn was modified by depositing a SiOx-coating using a plasma-enhanced, chemical vapour deposition (PECVD) process with hexamethyldisiloxane (HMDSO) as precursor material. After applying the SiOx coating, the fibre was impregnated with a fine-grained cement suspension to process mineral-impregnated carbon fibres (MCF). After advanced hydration, the MCF were investigated in respect of their flexural strength as well as their porosity. Moreover, the MCF were implemented in a fine-grained concrete matrix and assessed with respect to their pull-out behaviour.

It was found that the plasma generated SiOx coating led to a significant increase in maximum pull-out force, indicating better bonding between the modified carbon fibre yarns and the concrete matrix. This is attributed to a more pronounced pozzolanic reaction induced by the SiOx-films, promoting the local formation of calcium silicate hydrate (CSH) directly on the multifilament yarns, as supported by thermal gravimetric and microscopic analysis. However, it was also found that the deposition of the SiOx-films onto the CF resulted in more porosity in the impregnated cementitious matrix's structure, as proven by mercury intrusion porosity measurements. The higher porosity induced in turn a decrease in flexural strength for the MCF with high SiOx deposition.

It can be concluded that the deposition of a SiOx film onto the CF surfaces via plasma treatment is an innovative, promising approach toward enhancing the interactions between fibre and the cementitious matrix, but the process and material parameters need to be well balanced with regard to the microstructure and mechanical properties of the MCF.



中文翻译:

等离子体产生的碳纤维氧化硅涂层,用于改善与矿物基浸渍材料和混凝土基体的粘结

为了改善其与胶凝材料的粘结性能,通过使用以六甲基二硅氧烷(HMDSO)为前驱体材料的等离子体增强化学气相沉积(PECVD)工艺沉积SiO x涂层,对碳纤维(CF)纱线的表面进行了改性。涂覆SiO x涂层后,用细粒水泥悬浮液浸渍纤维,以处理矿物浸渍的碳纤维(MCF)。在高级水合后,研究了MCF的抗弯强度和孔隙率。此外,MCF是在细粒混凝土基质中实施的,并对其拉拔性能进行了评估。

发现等离子体产生的SiO x涂层导致最大拉拔力显着增加,表明改性碳纤维纱与混凝土基体之间的粘结性更好。这归因于由SiO x膜引起的更明显的火山灰反应,这促进了热重量分析和显微分析的支持,直接在复丝纱线上局部形成水合硅酸钙(CSH)。但是,还发现,SiO x膜在CF上的沉积会导致浸渍水泥基结构的孔隙率增加,这已通过压汞法测得。具有较高SiO x的MCF的较高孔隙度反过来导致其抗弯强度降低 沉积。

可以得出结论,通过等离子体处理将SiO x膜沉积到CF表面上是一种创新的,有前途的方法,可以增强纤维与水泥基体之间的相互作用,但在工艺和材料参数方面,必须进行合理的平衡MCF的微观结构和力学性能。

更新日期:2020-05-08
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