A chemical vapor condensation (CVC) process using the pyrolysis of metal-organic precursors was applied to produce the nanosized powders. Morphology and phase changes of the synthesized powder as a function of CVC parameters were investigated by XRD, BET and TEM. The agglomerated nanosized monoclinic powders with nearly spherical shape and 10-38 nm in mean diameter could be obtained. Conditions to produce the nanopowders are presented in this paper

nanopowder was synthesized by chemical vapor condensation (CVC) process and its photocatalytic property depending on microstructure was considered in terns of decomposition rate of organic compound. In order to control microstructure of nanopowder such as particle size and degree of agglomeration, precursor flow rate representing number concentration was changed as a process variable. In TEM observation, spherical nanoparticles with average size of 20 nm showed gradual increases in particle size and degree of agglomeration with increase of precursor flow rate. Also decomposition rate of organic compound increased with decreasing precursor flow rate. Thus, it was concluded that photocatalytic property was enhanced by targe surface area of disperse nanoparticles synthesized at lower precursor flow rate condition in CVC process

Fe-Co nanocomposite powders with different composition were prepared by chemical vapor condensation (CVC) process and their characterizations were studied by means of X-ray diffraction, transmission electron microscopy, and vibrating sample magnetometer. The particles having the mean size of 5~25 nm consisted of metallic cores and oxide shells. The Co contents and particle size increased with increasing the carrier gas flow rate of Co precursor. The saturation magnetization and coercivity increased with increasing Co content. and the saturation magnetization maximized at the 40 wt.%Co. The Fe-Co nanocomposite powder oxidized at showed the maximum coercivity of 1739 Oe.

나노미터 크기의 결정립을 가지는 나노분말 및 나노복합분말의 제조와 특성에 관한 연구가 매우 활발하다. 나노복합분말의 제조방법에는 기상증발후 응축법, 화학응축법, 기계적합금법 등이 있으나, 고순도 및 균일한 크기분포의 분말과 응집되지 않은 분말의 제조 조건을 가장 잘 만족하는 방법은 화학기상응축법(Chemical Vapor Condensation; CVC)이다. 본 연구그룹 에서는 CVC밤법으로 이용하여 공구/금형재료에 가장 많이 사용되는 WC/Co 합금

Nanosized tungsten carbide powders were synthesized by the chemical vapor condensation(CVC) process using the pyrolysis of tungsten hexacarbonyl(). The effect of CVC parameters on the formation and the microstructural change of as-prepared powders were studied by XRD, BET and TEM. The loosely agglomerated nanosized tungsten-carbide() particles having the smooth rounded tetragonal shape could be obtained below in argon and air atmosphere respectively. The grain size of powders was decreased from 53 nm to 28 nm with increasing reaction temperature. The increase of particle size with reaction temperature represented that the condensation of precursor vapor dominated the powder formation in CVC reactor. The powder prepared at was consisted of the pure W and cubic tungsten-carbide (), and their surfaces had irregular shape because the pure W was formed on the powders. The and W powders having the average particles size of about 5 nm were produced in vacuum.