| Summary: | 博士 === 國立高雄第一科技大學 === 工程科技研究所 === 94 === Abstract
In this study, the high-speed steels were used as the substrates for sputtering. Cr
and Al containing diamond-like carbon films deposited by unbalanced magnetron
sputtering to improve the adhesion of diamond-like carbon film as well as
high-precision, high-speed and continuous dry cutting in high-temperature environment.
The three main subjects in this study are as follows:
1. To find the optimum process parameters by Taguchi Method.
2. To study the effect of main process parameters on the properties of films.
3. To analyze the high-temperature properties of films.
We used the Raman、FE-SEM, EDS, GDS, TGA, OM, Vickers’ microhardness, 3D
iv
surface profile tester, scratch and wear test to characterize the properties of films. The
results are as follows：
The optimum process parameters obtained by Taguchi method were as follows：
♦ Cr target current = 2 A
♦ Al target current = 2 A
♦ C2H2 flow rate = 12 sccm
♦ Bias voltage = -50 V
♦ Argon flow rate = 20 sccm
♦ Pulse frequency = 40 KHz
♦ Deposition time = 120 minutes.
Also, the wear coefficient of the Cr and Al containing diamond-like carbon film
deposited by optimum parameters is 0.18 and its adhesion can reach 62.13N.
Cr and Al containing diamond-like carbon films in this study exhibit the fine
columnar grain microstructure and are composed of sp2, sp3, Cr3C2, Cr7C3 and some
amorphous phase. Furthermore, we also found some results in effect of different process
parameters on the properties of films such as：
(1) The film adhesion can reach 60N and has good wear resistance when the
deposition distance is 6 ~ 8 cm and deposition time is between 80 ~ 120
minutes.
(2) When Al content of the film increase, the film hardness and adhesion will
decrease. The Al content of the film in this study shall be lower than 14.5 wt%
in order to get the better wear resistance.
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(3) The films have DLC properties to reduce the wear coefficient and to improve
the wear resistance when the C2H2 flow rate is 9 ~ 12 sccm.
(4) The film has the best wear resistance when the bias voltage is equal to -100V.
In high-temperature properties of films, the applicable heat treatment time is equal
to 30 minutes in 600℃ high-temperature environments with considering the wear
resistance and the adhesion of films, time cost and heat deformation. Also, after
annealing above 600℃, the Cr3C2 and C7C3 phases were precipitated and a dense
protective film of complex Cr2O3 and Al2O3 oxides was formed on the film surface for
better hardness, wear resistance and high temperature properties of films. Besides, the
adhesion of film was slightly increased from 62.13N to 68.47N by annealing at 600℃.
However, the adhesion of film was worse by annealing above 700℃ due to the large
variation in coefficient of thermal expansion of composing phases.
In conclusion, the Cr and Al containing diamond-like carbon films deposited by
optimum process parameters obtained by Taguchi method have low wear coefficient of
0.18 and high adhesion of 62.13N, so the film can be applied in a high-temperature
condition of 600℃.
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