Higher Silicon Carbide Research Articles

Assessment of impact load effect on self-sensing of cement composites incorporating hybrid silicon carbide-graphite under various environmental conditions

This study investigates the self-sensing abilities of hybrid silicon carbide-graphite cement composites (HSCGC) under various environmental conditions, focusing on dynamic impacts. Integrating silicon carbide (SiC) and graphite enhances the mechanical and electrical properties of these composites. Tests showed that composites with 30 % SiC and 2 % graphite had a 14.1 % increase in compressive strength and up to 85 % decrease in electrical resistivity. Water absorption reduced by 3.25 %, indicating better durability. Impact resistance ratios (IRR) varied with humidity and impact angles, with the highest IRR observed at 70 % humidity and a 30-degree angle. Self-sensing responses indicated that higher SiC and graphite content maintained stable conductivity, especially at 60 and 90-degree angles. Temperature changes affected resistivity, negligible at −10°C and increased at 45°C. The study concludes that HSCGCs are suitable for smart construction materials, capable of real-time environmental and structural monitoring, advancing predictive models and control systems.

Investigating the valence balance of adding Nano SiC and MWCNTs on the improvement properties of copper composite using mechanical alloying and SPS techniques

This study presents a comprehensive investigation of copper-based nanocomposites reinforced with silicon carbide (SiC) nanoparticles and multi-walled carbon nanotubes (MWCNTs). The manufacturing procedure involved powder metallurgy techniques followed by spark plasma sintering (SPS). Microstructural analysis revealed a notable reduction in particle size (from 23.72 μm to 18.31 μm) and crystallite size (from 104.32 nm to 87.36 nm) with the addition of reinforcements. The bulk microstructure exhibited a reduction in grain size by approximately 13.1 %. XRD analysis confirmed the absence of new phases. Evaluation of SPS parameters demonstrated varying density and porosity, with the highest relative density of 99.96 % observed in pure copper composites. Hardness measurements indicated that surface hardness surpassed cross-sectional values, with the lowest recorded value being 64.79 HV for composite Cu-5%SiC-1%MWCNTs (S4). Wear rate analysis revealed an increase, with pure copper composites exhibiting a wear rate of 1.78 × 10^-4 mm3/m, while composite S4 displayed a rate of 3.25 × 10^-4 mm3/m under a load of 5 N. Coefficient of Friction (COF) exhibited significant fluctuations, influenced by the applied load and composite composition. Thermal conductivity decreased with higher SiC and MWCNT content, with sample S1 exhibiting the highest thermal conductivity among reinforced composites. Electrical conductivity trends were influenced by the type and concentration of reinforcing particles, resulting in an increase of approximately six times in composite S4 compared to the pure sample.

Microstructure Characterization on Silicon Carbide Formation from Natural Wood

Dark red meranti and kapur,are two important types of wood in Malaysia were used as precursors to fabricate porous silicon carbide. A carbon template was produced by pyrolysis at 850o C in an oxygen free atmosphere. The carbon template was further subjected to infiltration process with silicon. The infiltration process was carried out in a tube furnace in argon flow at 1500o C with two different holding times; 2 hours and 3 hours. Thermo gravimetric analysis was done to investigate the decomposition behavior of the two species. The resulting silicon carbide was characterized by XRD. The formation of silicon carbide and also excess silicon were found. The microstructure was characterized by scanning electron microscope (SEM). An increase in holding time during infiltration increased the density as well as formation of silicon carbide (SiC). Dark red meranti precursor is likely suitable for production of silicon carbide compared to kapur due to the higher SiC

Toxicological investigations on the respirable fraction of silicon carbide grain products by the in vitro vector model

Increased lung cancer incidence with workers at the production site of crude silicon carbide (SiC) using the Acheson process has been reported. Several agents derived from the process were discussed as causative factors. Recently concern had been expressed about the presence of cleavage fragments (CFs) in commercial products fulfilling the WHO criteria for fibers. This study has focused on the toxicological significance of such CFs. The test samples were respirable fractions of five different commercial samples of SiC grains. The CF content (scanning electron microscopy) was in the range 17–493 fibers/µg. Crystalline silica and whiskers could not be detected. Quartz DQ12, cristobalite, SiC whisker, UICC crocidolite and electrocorundum were used as control reference samples. Biological activity was assessed with the in vitro vector model (VM) on ex vivo rat and guinea pig alveolar macrophages (AMs). The dose range of the VM is derived from calculated AM loads from intratracheal instillation experiments and confirmed by measured AM loads from inhalation studies on alumina monohydrate particles with low biological activity: ≤120 pg/AM. The response of the references was clearly different from that of the SiC grains which yielded low toxicity overall. However, the parameter reactive oxygen species secreted by AMs was elevated at the higher SiC doses, but not related to the CF content of these samples. Our data showed that CFs seem to have no biological relevance. This is in agreement with results from recent studies in which no carcinogenic activity had been demonstrated for CFs.

Investigation of Cu-SiC Composite Preforms during Cold Upsetting

Cold upsetting experiments were carried out on sintered Cu-SiC preforms in order to evaluate their deformation characteristics. Powder preforms of 0.85, 0.90, and 0.95 initial preform density and 0.60 of initial aspect ratio were subjected to incremental compressive loading of 0.02 MN until fracture appeared at free surfaces. The effects of silicon carbide content and initial fractional density of the preforms on deformation behavior have been investigated thoroughly by using Zinc stearate as a lubricant. Dimensions such as height, contact, and bulged diameters, and densities were measured for each test. Analysis of the experimental data has shown the power law relationship between fractional theoretical density and e (ϵ z −ϵθ). Further, it was found that the preforms of lower silicon carbide content show higher values of deformation properties like the axial stress and the Poisson's ratio than higher silicon carbide preforms, provided that the initial fractional density taken is kept constant.