A Simple Way to Prepare C/SiC Spring

Abstract

A new method to form helical C/SiC spring is proposed. Using paraffin mold as a sacrificial core, unidirectional carbon fiber bundles (infiltrated with resin) are wrapped around the mold to form helical spring, and after resin curing, the mold is removed, leaving a preform of C/SiC spring. Following densification is finished with precursor infiltration and pyrolysis (PIP) process. The spring constant of C/SiC spring reaches 7.88 N/mm and could be regulated by varying composite density and carbon fiber content. The spring properties could be improved by twisting the carbon fibers at 35-50 twist/m. The restoration ratio reaches 100%, but energy dissipation happens during unloading process. After oxidation in air at 1200°C for 10 min, the spring has an 82.4% spring constant remaining ratio.

Fabrication and Ablation Studies of 4D C/SiC Composite Nozzle Under Liquid Propulsion

“…Linear ablation rate of C/SiC composite under plasma flow is reported to be in the range of 0.699-7.0 mm/s. 29 Under the liquid propulsion conditions, it is reported to be 0.250 AE 0.023 mm/s, while the overall mass ablation rate is reported up to 0.246 kg/m 2 s. 13 The ablation rate of the 4D C/SiC nozzle is found to be lower than the literature values for the similar test conditions due to the 4D fiber architecture which holds the matrix from all the directions and does not allow the loosened material to fly off easily with the exhaust gases. The role of the fiber and matrix during the ablation has been discussed in the next section.…”

“…However, oxidation studies of the C/SiC composites have been carried out by many researchers under the oxy-acetylene flame. [13][14][15] But oxy-acetylene flame does not simulate the rocket motor exhaust conditions with respect to the chemical composition of the oxidizing gases, temperature, pressure, and the shear forces. [13][14][15] Therefore, the nozzle material should be evaluated for the key properties before the actual use as a rocket motor nozzle of any system.…”

“…[13][14][15] But oxy-acetylene flame does not simulate the rocket motor exhaust conditions with respect to the chemical composition of the oxidizing gases, temperature, pressure, and the shear forces. [13][14][15] Therefore, the nozzle material should be evaluated for the key properties before the actual use as a rocket motor nozzle of any system. It is desired that the nozzle material should have uniform thermomechanical properties in all the directions apart from the high ceramic contents for the better ablation resistance.…”

“…Uniform properties and the high ablation resistance may be obtained in a composite by selecting an appropriate fiber architecture and the process parameters. [13][14][15][16][17][18] Ablation properties of the C/SiC composite nozzle fabricated via chemical vapor infiltration (CVI) process have been reported under the ethanol/oxygen propulsion system for a short duration. 13 Although the CVI-based composites posses better mechanical properties, their fabrication is difficult due to certain challenges, such as larger process time and density gradation across the composite thickness.…”

Intelligent Electric Power Systems with Active-Adaptive Electric Networks: Challenges for Simulation Tools

“…As a solution to the problem of obtaining sufficiently complete and reliable information about the processes in the IES a hybrid modeling approach based on using different modeling approaches is proposed [11,12].…”