Kazuyuki Oguri

Tribological properties and characterization of diamond-like carbon coatings with silicon prepared by plasma-assisted chemical vapour deposition

Abstract Amorphous C-Si coatings containing hydrogen (a-C-Si-H) were formed by a d.c. glow discharge method from reactant gases of CH4, SiCl4, H2, and argon. Coatings with a smooth surface, a hardness of HV 2000 and adhesion to steel substrates were obtained below 550 °C at a deposition rate of 1–4 μm h-1. The ball-on-disk test, against steel with no lubricant in ambient atmosphere, revealed that the friction coefficient μ of the a-C-Si-H coatings changed markedly with the carbon content. μ abruptly decreased from 0.43 to 0.16 at around 60 at.% C (composition excluding hydrogen) and reached a minimum value as low as 0.04 in a range of about 75–85 at.% C content. Laser Raman spectroscopy indicated that the low-friction a-C-Si-H coatings consisted of diamond-like carbon with silicon (DLC-Si). The μ value of 0.04 was below one-third that of DLC coatings without silicon, where μ = 0.12–0.20. The wear of both the DLC-Si and the counter steel ball was very small.

Effect of N2-to-TiCl4 flow rate ratio on the properties of TiN coatings formed by d.c. discharge plasma-assisted chemical vapor deposition

Abstract Attempts have been made to clarify the effect of the N 2 -to-TiCl 4 flow rate ratio on properties of TiN coatings which were formed on M2 steel and pure iron at a temperature of 550 by a d.c. glow discharge method from mixed gases of TiCl 4 , N 2 , H 2 and argon. The deposition rate of the coatings saturated at an N 2 -to-TiCl 4 flow rate ratio of 8 to 9. The composition and hardness of the coatings remained unchanged with the N 2 -to-TiCl 4 flow rate ratio except for the maximum ratio of 14.3, whereas the preferred orientation and microstructure changed markedly from (111) to (200), and from columnar to non-oriented. The coatings deposited at an N 2 -to-TiCl 4 flow rate ratio of 3 to 6, which resulted in the (200) preferred orientation and fine grained dense structure, showed greater adhesion strength.

Effect of excess carbon on the hardness of SiC and TiC coatings formed by plasma-assisted chemical vapor deposition

On etudie egalement les etats de liaison des atomes de carbone en exces dans leurs revetements, par spectroscopie Raman