In order to determine the wear properties of CVD ceramic coatings, wear process was evaluated using the coated pin of Falex Tribosystem. Also, in order to determine the effects of coating material on wear process, TiC,N of thickness 5m∼6m coated by Thermal CVD method were applied. The wear property of TiC,N film, the higher the deposition temperature was, the closer the lattice parameter was to the amount of the standard power, and the grain size increased. According to the wear formation, under the control that there is on specific wear rate wear parameter and coating delamination, decrease with increasing sliding friction and when the coating delamination happened.
Mono- and few-layer graphenes were grown on Ni thin films by rapid-thermal pulse chemical vapor deposition technique. In the growth steps, the exposure step for 60 s in H2 (a flow rate of 10 sccm (standard cubic centimeters per minute)) atmosphere after graphene growth was specially established to improve the quality of the graphenes. The graphene films grown by exposure alone without H2 showed an intensity ratio of IG/I2D = 0.47, compared with a value of 0.38 in the films grown by exposure in H2 ambient. The quality of the graphenes can be improved by exposure for 60 s in H2 ambient after the growth of the graphene films. The physical properties of the graphene films were investigated for the graphene films grown on various Ni film thicknesses and on 260-nm thick Ni films annealed at 500 and 700˚C. The graphene films grown on 260-nm thick Ni films at 900˚C showed the lowest IG/I2D ratio, resulting in the fewest layers. The graphene films grown on Ni films annealed at 700˚C for 2 h showed a decrease of the number of layers. The graphene films were dependent on the thickness and the grain size of the Ni films.
An optimum route to synthesize composite powders with homogeneous dispersion of carbon nanotubes (CNTs) was investigated. nanocomposite powders were fabricated by thermal chemical vapor deposition of gas over nanocomposite catalyst prepared by selective reduction of metal powders. The FT-Raman spectroscopy analysis revealed that the CNTs have single- and multi-walled structure. The CNTs with the diameter of 25-43 nm were homogeneously distributed in the powders, and their characteristics were strongly affected by a kind of metal catalyst and catalyst size. The experimental results show that the composite powder with required size and dispersion of CNTs can be realized by control of synthesis condition
Multi-walled carbon nanotubes (CNTs) were prepared by thermal chemical vapor deposition (CVD) and microwave plasma chemical vapor deposition (MPCVD) using various combination of binary catalysts with four transition metals such as Fe, Co, Cu, and Ni. In the preparation of CNTs from acetylene precursor by thermal CVD, the CNTs with very high yield of 43.6 % was produced over Fe-Co/Al2O3. The highest yield of CNTs was obtained with the catalyst reduced for 3 hr and the yield was decreased with increasing reduction time to 5 hr, due to the formation of FeAl2O4 metal-aluminate. On the other hand, the CNTs prepared by acethylene plasma CVD had more straight, smaller diameter, and larger aspect ratio(L/D) than those prepared by thermal CVD, although their yield had lower value of 27.7%. The degree of graphitization of CNTs measured by Id/Ig value and thermal degradation temperature were 1.04 and 602℃, respectively.