Improved Mechanical Properties of SiC Fibers Pyrolyzed from Polycarbosilane under Tension

Chu, Zengyong; Feng, Changjian; Song, Yongcai; Wang, Jun; Wang, Kunjie; Li, Xiaodong

doi:10.1515/secm.2002.10.2.131

Cited by 12 publications

(4 citation statements)

References 10 publications

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“…Wang et al [16][17][18][19][20] have pointed out that coarser grain size resulting from higher temperature can lead to flaws in SiC fibers and further the declining properties of SiC fibers. As shown in Fig.5, the surface of the SiC fiber after heat treatment at 1100°C for 0.5h is very smooth (Fig.5 (a)), while the surface of the SiC fiber after heat treatment at 1100°C for 1.5h become unsmooth (Fig.5 (b)) to some degree.…”

Section: Resultsmentioning

confidence: 99%

Effect of microwave sintering time on the flexural properties of the SiC/SiC composites

Yang

Zhou

et al. 2015

Ceramics International

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Section: Resultsmentioning

confidence: 99%

Effect of microwave sintering time on the flexural properties of the SiC/SiC composites

Yang

Zhou

et al. 2015

Ceramics International

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“…During the pyrolysis, considerable volume shrinkage occurs accompanied by considerable weight loss and density increase, and at the same time, a compressive stress arises. To balance this stress, as expected, too lower a tensile stress cannot take effect and a too higher one may result in the failure of filaments or the whole bundle [4]. Although commercial SiCbased fibres have been produced from various polycarbosilanes, little literature was released on the pyrolysis under tensions.…”

Section: Introductionmentioning

confidence: 88%

“…But the solid line for a 2.5 m-bundle is very applicable, especially to the multi-step continuous pyrolysis of polycarbosilane bundles. For example, we have successfully prepared high strength continuous SiC fibres in a pilot scale using this tension schedule [4]. Of course, in the practical uses, a 5step or 4-step tension schedule may be enough.…”

Section: A Tension Schedule Proposed For the Pyrolysis Of Polycarbosimentioning

confidence: 99%

“…Yajima pointed out the importance of firing tension in the preparation of high strength SiC fibres as it can eliminate bend portions [5], unfortunately, however, no tensile schedule was suggested in the patent. Our own results also showed that a tensile strength improvement of more than 10% could be achieved using an experiential tensile schedule [4]. Therefore, in this paper we are going to discuss, in the theoretical terms, what is the upper limit tension loaded on a polycarbosilane bundle pyrolysis up to a certain temperature and what a specific tension schedule is the most suitable for the pyrolysis of polycarbosilane bundles.…”

Section: Introductionmentioning

confidence: 97%

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Theoretical Aspects of a Tension Schedule Proposed for the Pyrolysis of Polycarbosilane Bundles

Chu

Feng

Song

et al. 2002

Advanced Composites Letters

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To prepare high strength SiC fibres that cannot be broken with a shear force because of the absence of bend portions, a firing tension is necessary in the pyrolysis of polycarbosilane bundles. However, up to now, no theoretical discussions were released on the tension schedule. Some theoretical aspects, therefore, such as constitutive model, Weibull parameters, peak load/stress, survival probability and upper limit tension were discussed and a theoretical tension schedule was proposed in the paper.

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Polymer‐Derived High‐Temperature Nonoxide Materials: A Review

Zhou

2023

Adv Eng Mater

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The synthesis of polymer-derived nonoxide materials such as carbides, borides, and nitrides started in the 1970s and slowly progressed into the 1980s, with silicon carbide (SiC) fibers as the prime examples. [1] In the 1990s, the research activities in this area became more intensive, with multiple efforts devoted to understanding the polymer-to-ceramic conversion mechanisms, resulting microstructures, and mechanical properties. In the 2000s, relying on the liquid precursor nature and advancement in chemistry, new techniques (e.g., electrospinning, coating, and precursor infiltration) and new precursors were introduced. Understanding of the crosslinking and thermal conversion process was improved. For example, SiC fibers were improved from amorphous silicon oxycarbide (SiOC) to low-oxygen SiC fibers and then to near-stoichiometric SiC fibers. SiC thin films of 8-190 μm thickness were reported in 2009. [2] These films can stand alone, and high mechanical properties and optoelectronic properties were achieved. Because of these advantages, they were proposed to be used in microelectromechanical systems (MEMS) and optoelectronic devices. In recent decades, additive manufacturing was used to form complex shapes. [3] Also, different one-pot precursor synthesis approaches were reported. [4] The pyrolyzed ceramic systems were frequently used in a powder format and can be further processed with traditional forming processes such as spark plasma sintering, hot pressing, thermal treatment, etc. [5,6] The advantages of using the polymerderived approach for such high-temperature nonoxide material formations involve several aspects. Compositions can be designed based on molecular-level interactions and conversion of polymeric precursors to composites. Through a synergistic selection and combination of polymer molecules of different architectures and additives, a large family of functional, structural, resilient, and versatile materials can be created. Pyrolysis conditions can also be varied to create different property systems. Species intermixing can be achieved at the true atomic level. It enables functional properties for inert systems and harsh environmental stability for far-from-equilibrium conditions. Additional advantages include low processing temperature (such as a few hundred degrees Celsius lower) and versatile shape achievement. The final materials can be fibers, coatings, membranes, powders, bulk parts, porous forms, infiltrating phases, and complex 3D-printed shapes, [3a] among others. Using the polymer-derived approach to form high-temperature ceramics also enables composition homogeneity and purity, thanks to the uniform mixing of different precursors and additives and high-purity chemical precursors. It can also create compositions that may be impossible with conventional routes, [7] such as sintering.The common challenges are as follows. Polymer-derived nonoxide composites are in a metastable state. At high temperatures, the composition and microstructure can continue to evolve and

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Improved Mechanical Properties of SiC Fibers Pyrolyzed from Polycarbosilane under Tension

Cited by 12 publications

References 10 publications

Effect of microwave sintering time on the flexural properties of the SiC/SiC composites

Effect of microwave sintering time on the flexural properties of the SiC/SiC composites

Theoretical Aspects of a Tension Schedule Proposed for the Pyrolysis of Polycarbosilane Bundles

Polymer‐Derived High‐Temperature Nonoxide Materials: A Review

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