SiC nanowires were successfully synthesized without catalyst by pyrolysis of silicon-containing pitch-derived carbon materials in a closed graphite crucible. These silicon-containing carbon materials were obtained by homogenization and co-carbonization of a hybrid precursor consisting of the toluene soluble fraction of coal tar pitch with polycarbosilane (PCS). The composition, morphology and structure of the nanowires were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and selected area electron diffraction (SAED). The influence of pyrolysis temperature on the growth of
A three-dimensional steady-state numerical model of oil-gas separator with inlet-collision structure used in small-sized Variable Refrigerant Flow (VRF) system was established. RNG k-ε model was used in gas field and DRW model was chosen for oil droplets tracking. The influence of inlet-collision on velocity distribution, separation efficiency and pressure loss were studied. The results showed that the inlet-collision structure which had smaller radio of inner pipe length to cyclone bodys height could achieve the same separation efficiency as the no inlet-collision structure with bigger cyclone diameter. Higher separation performance could be obtained when the inlet-collision proportion was less than 26.57% and inlet velocity was about 24 m·s-1.
Hafnium carbide ceramic powders were prepared by pyrolysis of a novel precursor, which was synthesized via one pot method using hafnium tetrachloride, acetylacetone, methanol, and hydroquinone as raw materials. The composition, morphology and microstructure of the pyrolysis products were characterized by XRD, FTIR, SEM/EDS, TEM, and SAED. The pyrolysis behavior of the obtained HfC precursor was investigated by TG-DSC and TG-MS. The results show that the ceramization of the HfC precursor starts at about 600℃, and the formation of HfC ceramics is initiated at about 1300℃. At temperature above 1500℃, the precursor completely transforms into HfC ceramics and free carbon. The as-obtained HfC phase has a single crystal structure and the size of the HfC particles ranges from 50 to 100 nm. Formation of the HfC ceramics can be attributed to the carbothermal reduction reaction of the HfO 2 , which is produced by pyrolysis of the precursor at a relative low temperature. The growth of the HfC crystals is retarded by free carbon formed during pyrolysis of the precursor.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.