Silicon Carbide Whisker

Catalog	ACMA00031884
Description	SiC, Beta, 99+%
Synonyms	beta SiC
Density	3.216 g/cm³ (288k)
Content	beta- SiC>99+%, Free Carbon <0.05%
Decomposition Temperature	2973 k
Fiber Diameter	0.1~0.8 um
Hardness	9.5 Mohs
Length	2.0-60 um
Tensile Strength	20.8 Gpa
Thermal Expansion	6.58x10-6 at 373k; 2.98x10-6 at 1173k
Type	SiC Fiber Crystal Type: Beta

Case Study

Surface Modified Silicon Carbide Whiskers for Enhancing the Toughness of RBSC Ceramic Materials

Xue, Rong, et al. Ceramics International, 2021, 47(13), 18150-18156.

Silicon carbide whiskers coated with pyrolytic carbon layer (PyC-SiCw) can be introduced into reaction-sintered silicon carbide (RBSC) ceramics by chemical vapor deposition (CVD) to prepare SiCw/RBSC composites. The results show that when 10 wt% of PyC-SiCw is added, the fracture toughness of PyC-SiCw/RBSC composites is improved by 5.28 MPa m1/2, which is significantly higher than that of SiCw/RBSC composites and RBSC matrix.
Preparation procedure of PyC-SiCw/RBSC composites
· A pyrolytic carbon (PyC) coating was applied to SiCw at 900 ◦C using a mixture of propylene and hydrogen in a 1:10 ratio. This PyC-SiCw material was then mixed with water and a dispersant (KH-550) to create a stable suspension (Suspension 1). Separately, SiC powders, nano carbon black, and KH-550 were dispersed in water to form a second suspension (Suspension 2).
· The two suspensions were combined using ultrasonication and high-speed mechanical homogenization to create a uniform solution. This solution was dried using rotary evaporation and milling, followed by the addition of a PVA solution to increase the powder's plasticity.
· After pre-pressing and cold isostatic pressing, a green body preform measuring 5 × 5 × 50 mm3 was obtained. Next, the green body preform was carbonized at 1100 ◦C for 2 hours in a nitrogen atmosphere. Finally, the resulting green body was sintered at 1550 ◦C for 60 minutes in a vacuum furnace to produce PyC-SiCw/RBSC composites.

Silicon Carbide Whiskers and Montmorillonite for Improving the Ablation Resistance of Silicone Rubber Composites

Zhang, Guangwu, et al.Materials, 2016, 9(9), 723.

Using high-viscosity solid silicone rubber (SR) as the elastomer matrix, adding montmorillonite (MMT) to improve its ablation resistance, and adding silicon carbide whiskers (SiCw) as the second phase filler, the SiCw/MMT hybrid SR composite materials were prepared. Research showed that the introduction of SiCw can further improve the ablation resistance of SR composites without significantly reducing flexibility and increasing density.
Preparation procedure of SiCw/MMT-SR composites
· To make the MMT/SR masterbatch, MVS and MPVS (in a 4:6 ratio) were dissolved in THF, then MMT was added. The ratio of MMT to total SR was 25:75. The mixture was mixed for 3 hours at 1300 rpm, then THF was evaporated at 65 °C and the mixture dried at 60 °C for 24 hours in a vacuum.
· For the SR composites, the compounds were mixed in a two-roll open mixing mill at room temperature. SR and MMT/SR masterbatch were added first, followed by additives (SiCw and SiO2), then phenolic fibers were added slowly. DBPMH was added last. The compounds were compression-molded at 165 °C for 15 minutes at 10 MPa. The ablators were vulcanized in a mold with a diameter of 30 mm and thickness of 10 mm. Secondary vulcanization was carried out at 180 °C for 2 hours in an airflow drier.