U.S. patent application number 14/239902 was filed with the patent office on 2014-07-31 for film and method for manufacturing same.
This patent application is currently assigned to TOYOTA JIDOSHA KABUSHIKI KAISHA. The applicant listed for this patent is Yuichi Furukawa, Shuji Sotozaki. Invention is credited to Yuichi Furukawa, Shuji Sotozaki.
Application Number | 20140212689 14/239902 |
Document ID | / |
Family ID | 47882766 |
Filed Date | 2014-07-31 |
United States Patent
Application |
20140212689 |
Kind Code |
A1 |
Furukawa; Yuichi ; et
al. |
July 31, 2014 |
FILM AND METHOD FOR MANUFACTURING SAME
Abstract
Disclosed are a film with high strength which does not easily
deteriorate, and a method for manufacturing the film. A step for
manufacturing a film formed on the molding surface of a die,
includes an initial film-forming step for forming, on the molding
surface of the die, an initial film having a carbon film which has
a plurality of nano-carbons, and to which a plurality of fullerenes
are applied, and a nitrogen compound layer and a sulfurized layer
which are situated between the carbon film and the die, and an
intermittent heating step for intermittently heating the initial
film formed in the initial film-forming step under a non-oxidizing
atmosphere.
Inventors: |
Furukawa; Yuichi;
(Toyota-shi, JP) ; Sotozaki; Shuji; (Okazaki-shi,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Furukawa; Yuichi
Sotozaki; Shuji |
Toyota-shi
Okazaki-shi |
|
JP
JP |
|
|
Assignee: |
TOYOTA JIDOSHA KABUSHIKI
KAISHA
Aichi
JP
|
Family ID: |
47882766 |
Appl. No.: |
14/239902 |
Filed: |
September 13, 2011 |
PCT Filed: |
September 13, 2011 |
PCT NO: |
PCT/JP2011/070859 |
371 Date: |
February 20, 2014 |
Current U.S.
Class: |
428/697 ;
427/135 |
Current CPC
Class: |
C23C 8/02 20130101; B22C
9/061 20130101; C23C 8/80 20130101; B22C 9/12 20130101; C23C 8/28
20130101 |
Class at
Publication: |
428/697 ;
427/135 |
International
Class: |
B22C 9/12 20060101
B22C009/12 |
Claims
1-4. (canceled)
5. A method for manufacturing a film formed on a molding surface of
a die used for casting, comprising: an initial film-forming step
for forming, on the molding surface of the die, an initial film
including a carbon film, a nitrogen compound layer and a sulfurized
layer, the carbon film having a plurality of nano-carbons, and a
plurality of fullerenes which is applied to the carbon film, the
nitrogen compound layer and the sulfurized layer being situated
between the carbon film and the die; and an intermittent heating
step for intermittently heating the initial film formed in the
initial film-forming step under a non-oxidizing atmosphere, wherein
in the intermittent heating step, an oil-based release agent is
applied to the molding surface of the die on which the initial film
is formed, and then the casting is performed a plurality of times
using the die.
6. A film which includes a carbon film having a plurality of
nano-carbons, and which is formed on a surface of an iron-based
material, characterized by containing hard amorphous carbon,
Fe.sub.4N, Fe.sub.3C, martensite, and Fe.sub.3O.sub.4, and
sulfur-diffusion ratio in the carbon film which is over 50%.
7. The film according to claim 6, wherein said hard amorphous
carbon, Fe.sub.4N, Fe.sub.3C, martensite, and Fe.sub.3O.sub.4 are
identified by an X-ray diffraction method, and the sulfur-diffusion
ratio is found by mapping analysis with an EPMA.
Description
TECHNICAL FIELD
[0001] The present invention relates to a film formed on the
surface of an iron-based material, and to a method for
manufacturing the film.
BACKGROUND ART
[0002] Conventionally, publicly known is a technique for forming a
predetermined film on the molding surface of a die (the surface of
an iron-based material) in order to accomplish decrease of
mold-release resistance and the like in die casting (for example,
see Patent Literature 1).
[0003] Patent Literature 1 discloses a technique for forming a film
on the molding surface of a die by applying fullerenes to a carbon
film having nano-carbons such as carbon nanotube.
[0004] According to Patent Literature 1, by filling apertures in
the carbon film with the fullerenes to smoothen the uneven surface
of the carbon film, mold-release resistance is reduced.
[0005] However, if the technique described in Patent Literature 1
is used, in the case of incomplete combination of the carbon film
and the fullerenes, the fullerenes are removed by alkaline solvent,
and the film deteriorates. Moreover, the film is easily peeled off
because the film has insufficient strength.
[0006] Therefore, the technique described in Patent Literature 1
has room for improvement.
CITATION LIST
Patent Literature
[0007] Patent Literature 1: JP 2010-36194 A
SUMMARY OF INVENTION
Problem to Be Solved By the Invention
[0008] The objective of the present invention is to provide a film
with high strength which does not easily deteriorate, and a method
for manufacturing the film.
Means for Solving the Problem
[0009] A first aspect of the invention is a method for
manufacturing a film formed on a surface of an iron-based material,
including an initial film-forming step for forming, on the surface
of the iron-based material, an initial film including a carbon
film, a nitrogen compound layer and a sulfurized layer, the carbon
film having a plurality of nano-carbons, and a plurality of
fullerenes which is applied to the carbon film, the nitrogen
compound layer and the sulfurized layer being situated between the
carbon film and the iron-based material, and an intermittent
heating step for intermittently heating the initial film formed in
the initial film-forming step under a non-oxidizing atmosphere.
[0010] Preferably, the iron-based material is a die used for
casting, which has a molding surface, in the initial film-forming
step, the initial film is formed on the molding surface of the die,
and in the intermittent heating step, an oil-based release agent is
applied to the molding surface of the die on which the initial film
is formed, and then the casting is performed a plurality of times
using the die.
[0011] A second aspect of the invention is a film which includes a
carbon film having a plurality of nano-carbons, and which is formed
on a surface of an iron-based material. The film contains hard
amorphous carbon, Fe.sub.4N, Fe.sub.3C, martensite, and
Fe.sub.3O.sub.4. Sulfur-diffusion ratio in the carbon film is over
50%.
[0012] Preferably, hard amorphous carbon, Fe.sub.4N, Fe.sub.3C,
martensite, and Fe.sub.3O.sub.4 are identified by an X-ray
diffraction method, and the sulfur-diffusion ratio is found by
mapping analysis with an EPMA.
EFFECTS OF THE INVENTION
[0013] The present invention makes it possible to minimize
deterioration and separation of a film.
BRIEF DESCRIPTION OF DRAWINGS
[0014] FIG. 1 shows a step for manufacturing a film according to an
embodiment of the present invention.
[0015] FIG. 2 illustrates an initial film.
[0016] FIG. 3 illustrates the film according to an embodiment of
the present invention.
[0017] FIG. 4 shows a result of mapping analysis of the initial
film with an EPMA, in which FIG. 4(a) shows carbon present in the
initial film, and FIG. 4(b) shows sulfur present in the initial
film.
[0018] FIG. 5 shows a result of mapping analysis of the film
according to an embodiment of the present invention with the EPMA,
in which FIG. 5(a) shows carbon present in the film according to an
embodiment of the present invention, and FIG. 5(b) shows sulfur
present in the film according to an embodiment of the present
invention.
[0019] FIG. 6 shows a result of mapping analysis of a comparison
film with the EPMA, in which FIG. 6(a) shows carbon present in the
comparison film, and FIG. 6(b) shows sulfur present in the
comparison film.
DESCRIPTION OF EMBODIMENTS
[0020] With reference to FIGS. 1 to 3, described below is a step Si
for manufacturing a film 1 as an embodiment of a method for
manufacturing a film according to the present invention.
[0021] The film 1 is formed on the molding surface of a die used
for die casting and the like.
[0022] The step S1 is a step for forming the film 1 on the molding
surface of the die.
[0023] In the present embodiment, the die is an iron-based material
made of alloy tool steel (JIS G4404) such as SKD61.l
[0024] As shown in FIG. 1, the step Si includes an initial
film-forming step S11 and an intermittent heating step S12.
[0025] The initial film-forming step S11 is a step for forming an
initial film 100 on the molding surface of the die. The initial
film-forming step S11 is a conventional technique, and specifically
is the step disclosed in JP 2010-36194 A. Therefore, detailed
explanation of the initial film-forming step S11 is omitted.
[0026] FIG. 2 illustrates the initial film 100 produced in the
initial film-forming step S11.
[0027] As shown in FIG. 2, the initial film 100 is a film produced
by the conventional technique, and includes a diffusion layer 110,
a nitrogen compound layer 120, a sulfurized layer 130, and a carbon
film 140.
[0028] The diffusion layer 110 is a part of the die into which
nitrogen is diffused, and is formed in the vicinity of the molding
surface of the die.
[0029] The nitrogen compound layer 120 is a layer containing
Fe.sub.3C and a nitrogen compound such as Fe.sub.2N or Fe.sub.3N.
The nitrogen compound layer 120 is formed on the diffusion layer
110.
[0030] The sulfurized layer 130 is a layer containing a sulfur
compound such as FeS. The sulfurized layer 130 is formed on the
nitrogen compound layer 120.
[0031] The carbon film 140 is a layer having nano-carbons. The
carbon film 140 is situated at the outermost part (the uppermost
part in FIG. 2) of the initial film 100.
[0032] The carbon film 140 has a plurality of hard amorphous
carbons 141, a plurality of nano-carbons 142, and a plurality of
fullerenes 143.
[0033] The hard amorphous carbon 141 is an amorphous material
consisting primarily of carbon. The plurality of hard amorphous
carbons 141 are scattered in roughly a position where the diffusion
layer 110 and the nitrogen compound layer 120 are formed.
[0034] The nano-carbon 142 belongs to the nano-carbons such as
carbon nanofiber, carbon nanotube, carbon nanocoil, and carbon
nanofilament. The plurality of nano-carbons 142 are formed to
extend toward the surface of the initial film 100 (extend upward in
FIG. 2) from the plurality of hard amorphous carbons 141. The
plurality of nano-carbons 142 extend to reach the surface of the
initial film 100.
[0035] The fullerene 143 is a carbon cluster consisting of a
plurality of carbon atoms, typified by C.sub.60. The fullerene 143
may be one of fullerene derivatives to which a predetermined
chemical modification is applied. The plurality of fullerenes 143
exist between the nano-carbons 142.
[0036] As mentioned above, the initial film 100 includes the carbon
film 140 having the plurality of nano-carbons 142, to which the
plurality of fullerenes 143 are applied, and the nitrogen compound
layer 120 and the sulfurized layer 130 which are situated between
the carbon film 140 and the die.
[0037] In the present invention, a method for manufacturing an
initial film is not limited as long as the initial film includes,
at least, a carbon film having nano-carbons, to which a plurality
of fullerenes are applied, and a nitrogen compound layer and a
sulfurized layer which are situated between the carbon film and the
die.
[0038] As shown in FIG. 1, the intermittent heating step S12 is a
step for intermittently heating, under a non-oxidizing atmosphere,
the initial film 100 produced in the initial film-forming step
S11.
[0039] In the intermittent heating step S12, the initial film 100
is intermittently heated by actually performing die casting a
plurality of times using the die on which the initial film 100 is
formed.
[0040] Specifically, first, an oil-based release agent such as
mineral oil, synthetic oil, or vegetable oil is applied to the
molding surface of the die on which the initial film 100 is formed.
At this time, the oil-based release agent is applied to the molding
surface of the die so that the molding surface is completely
covered with the oil-based release agent. Thereby, the initial film
100 can avoid exposure to water and air, namely, can be under the
non-oxidizing atmosphere.
[0041] Next, the cavity of the die is filled with a molten metal,
such as aluminum alloy, with a high temperature (e.g. 600.degree.
C.), and then the die is left to stand for a predetermined period
(e.g. 5 seconds). At this time, the high-temperature molten metal
comes in contact with the molding surface of the die, and thereby
is cooled to a predetermined temperature (e.g. 300.degree. C.). In
other words, the initial film 100 is heated at a high temperature
by the molten metal immediately after supplying the molten metal to
the cavity of the die, and then is cooled at the temperature of the
molten metal rapidly cooled by the die.
[0042] Finally, the solidified metal (cast metal) is released from
the die.
[0043] By performing the above-mentioned process predetermined
times (e.g. 1000 times), the initial film 100 turns into the film
1. In other words, the film 1 is formed on the molding surface of
the die.
[0044] As mentioned above, in the intermittent heating step S12,
the die casting is performed a plurality of times under the
non-oxidizing atmosphere using the die on which the initial film
100 is formed. Thereby, a predetermined change in temperature
(heating and cooling) takes place in the initial film 100 a
plurality of times. In other words, the initial film 100 is
intermittently heated, which turns the initial film 100 into the
film 1.
[0045] In the present embodiment, the film 1 is formed on the
molding surface of the die. However, the present invention may be
applied not only to the molding surface of the die but also to the
surface of any iron-based material.
[0046] In the present embodiment, the oil-based release agent is
applied to the molding surface every a performance of the casting.
However, timing of applying the oil-based release agent to the
molding surface is not limited thereto as long as the initial film
100 can be kept under the non-oxidizing atmosphere.
[0047] In the present embodiment, applying the oil-based release
agent to the molding surface of the die enables the initial film
100 to be under the non-oxidizing atmosphere. However, if a method
except this also enables the initial film 100 to be under the
non-oxidizing atmosphere, a film according the present invention
may be manufactured.
[0048] In the present embodiment, the initial film 100 is
intermittently heated by actually performing the die casting the
plurality of times. However, the initial film 100 may be
intermittently heated by a laser, an ultrasonic wave, or the
like.
[0049] FIG. 3 illustrates the film 1 produced through the step
S1.
[0050] As shown in FIG. 3, the film 1 is a film produced by the
conventional technique, and includes a diffusion layer 10, a
nitrogen compound layer 20, a sulfurized layer 30, and a carbon
film 40.
[0051] The diffusion layer 10 is the diffusion layer 110 passed
through the intermittent heating step S12, and is formed in the
vicinity of the molding surface of the die.
[0052] The nitrogen compound layer 20 is the nitrogen compound
layer 120 passed through the intermittent heating step S12, and is
formed on the diffusion layer 10.
[0053] The nitrogen compound layer 20 is a layer containing
Fe.sub.3C and a nitrogen compound such as Fe.sub.4N. In other
words, the nitrogen compound layer 20 differs from the nitrogen
compound layer 120 of the initial film 100 in containing Fe.sub.4N.
When the nitrogen compound layer 120 goes through the intermittent
heating step S12, Fe.sub.2N or Fe.sub.3N present in the nitrogen
compound layer 120 of the initial film 100 turns into
Fe.sub.4N.
[0054] Fe.sub.4N has a dense structure compared with Fe.sub.2N or
Fe.sub.3N.
[0055] Therefore, the film 1 which includes the nitrogen compound
layer 20 containing Fe.sub.4N has one and a half times as large
peel strength (pressure at which the film separates from the die)
as the initial film 100 which includes the nitrogen compound layer
120 containing Fe.sub.2N or Fe.sub.3N.
[0056] Consequently, the present invention makes it possible to
manufacture the film 1 with high strength.
[0057] The sulfurized layer 30 is the sulfurized layer 130 passed
through the intermittent heating step S12, and is formed on the
nitrogen compound layer 20. The sulfurized layer 30 is formed to
reach the surface of the initial film 100.
[0058] The carbon film 40 is the carbon film 140 passed through the
intermittent heating step S12.
[0059] In the carbon film 40, the sulfurized layer 30 is wholly
formed. In other words, sulfur diffuses throughout the carbon film
40.
[0060] Thus, in the initial film 100, sulfur gathers in the root
(lower part in FIG. 2) of the carbon film 140, whereas in the film
1, sulfur diffuses throughout the carbon film 40.
[0061] Therefore, the film 1 has a friction coefficient smaller
than that of the initial film 100.
[0062] Consequently, the present invention makes it possible to
reduce mold-release resistance of the film 1.
[0063] The carbon film 40 has a plurality of hard amorphous carbons
41, a plurality of nano-carbons 42, and a plurality of fullerenes
43.
[0064] The hard amorphous carbon 41 is the hard amorphous carbon
141 passed through the intermittent heating step S12.
[0065] The hard amorphous carbon 41 is the hard amorphous carbon
141 which is densified by a part of the plurality of fullerenes 143
made amorphous through the intermittent heating step S12. Thus, the
hard amorphous carbon 41 has a structure denser than that of the
hard amorphous carbon 141 of the initial film 100.
[0066] The nano-carbon 42 is the nano-carbon 142 passed through the
intermittent heating step S12. The plurality of nano-carbons 42 are
formed to extend toward the surface of the film 1 (extend upward in
FIG. 3) from the plurality of hard amorphous carbons 41. The
plurality of nano-carbons 42 extend to reach the surface of the
initial film 100.
[0067] The fullerene 43 is the fullerene 143 passed through the
intermittent heating step S12.
[0068] The plurality of fullerenes 43 combine with the plurality of
nano-carbons 42, which makes the carbon film 40 dense.
[0069] Therefore, the plurality of fullerenes 43 are not removed by
alkaline solvent. Consequently, the present invention makes it
possible to prevent the film 1 from deteriorating.
[0070] Moreover, the plurality of fullerenes 43 diffuse through the
nitrogen compound layer 20 and the diffusion layer 10.
[0071] As mentioned previously, in the film 1, sulfur diffuses
throughout the carbon film 40. It is presumed that this is caused
by permeation of fullerenes 43 into the diffusion layer 10.
[0072] Specifically, it is presumed that, when the carbon film 140
goes through the intermittent heating step S12, mutual diffusion
takes place between a relatively great number of fullerenes 143
existing in the vicinity of the surface of the carbon film 140, and
a relatively great amount of sulfur existing in the root of the
carbon film 140, and consequently sulfur diffuses throughout the
carbon film 40.
[0073] It is preferable that the lower limit of the temperature at
which the initial film 100 is cooled in the intermittent heating
step S12 (the temperature of the molten metal rapidly cooled when
coming in contact with the molding surface of the die) is
240.degree. C. because generally, a fullerene is easy to diffuse at
240.degree. C. or more.
[0074] Additionally, it is preferable that the upper limit of the
temperature at which the initial film 100 is heated in the
intermittent heating step S12 (the initial temperature of the
molten metal) is 600.degree. C. because the carbon film 140 of the
initial film 100 may deteriorate by oxidation at the temperature
higher than 600.degree. C.
[0075] Based on an example and a comparative example, with
reference to FIGS. 4 to 6, described below are characteristics of a
film according to the present invention.
[0076] Before carrying out processes in the example and the
comparative example, mapping analysis of the initial film 100 was
performed using an EPMA (Electron Probe MicroAnalyzer). A section
where the mapping analysis was performed was a surface taken from
the surface of the initial film 100 toward the inside thereof.
[0077] FIG. 4 shows a result of the mapping analysis of the initial
film 100 with the EPMA. FIG. 4(a) shows carbon present in the
initial film 100, and FIG. 4(b) shows sulfur present in the initial
film 100.
[0078] Sulfur-diffusion ratio in the carbon film may be found from
the result of the mapping analysis.
[0079] Note that the sulfur-diffusion ratio in the carbon film is a
percentage of sulfur in the carbon film in the section where the
mapping analysis with the EPMA is performed. For example, if sulfur
diffuses throughout the carbon film, the sulfur-diffusion ratio is
considered to be 100%.
[0080] As shown in FIGS. 4(a) and 4(b), in the carbon film 140 of
the initial film 100, sulfur is not distributed wholly, and a
relatively great amount of sulfur exists in the root (lower part in
FIG. 4(b)). At this time, the sulfur-diffusion ratio in the carbon
film 140 of the initial film 100 is considered to be 50%.
[0081] On the other hand, the initial film 100 was analyzed by an
X-ray diffraction method. Thereby, it was found that the initial
film 100 contained hard amorphous carbon, Fe.sub.2N, Fe.sub.3C,
martensite, and Fe.sub.3O.sub.4.
EXAMPLE
[0082] First, the oil-based release agent was applied to the
molding surface of the die on which the initial film 100 was
formed, and thereby the initial film 100 was under the
non-oxidizing atmosphere.
[0083] Next, the cavity of the die was filled with molten aluminum
alloy of 600.degree. C., and the initial film 100 was heated for 5
seconds at 4000 kcal/m.sup.2 on the heat-transfer interface (the
molding surface of the die) with heat-transfer coefficient of 6000
W/m.sup.2K (600.degree. C., 50 MPa).
[0084] Finally, the solidified metal (cast metal) was released from
the die.
[0085] By performing the above-mentioned process 1000 times, the
film 1 was produced.
[0086] Mapping analysis of the film 1 was performed using the EPMA,
similarly to the initial film 100.
[0087] FIG. 5 shows a result of the mapping analysis of the film 1
with the EPMA. FIG. 5(a) shows carbon present in the film 1, and
FIG. 5(b) shows sulfur present in the film 1.
[0088] As shown in FIGS. 5(a) and 5(b), in the carbon film 40 of
the film 1, sulfur is distributed wholly, and uniformly exists even
in the vicinity of the surface of the film 1 (in the upper part in
FIG. 5(b)). At this time, the sulfur-diffusion ratio in the carbon
film 40 of the film 1 is considered to be 100%.
[0089] As mentioned above, the film 1 has the sulfur-diffusion
ratio larger than that of the initial film 100. Therefore, as
mentioned previously, the film 1 has the friction coefficient
smaller than that of the initial film 100, and consequently has the
mold-release resistance smaller than that of the initial film
100.
[0090] Note that the sulfur-diffusion ratio in the carbon film 40
of the film 1 is 100%, but is not limited thereto as long as the
friction coefficient of a film according to the present invention
is smaller than that of an initial film. In other words, it is only
necessary that the sulfur-diffusion ratio in the carbon film of the
film according to the present invention is over 50%.
[0091] On the other hand, the film 1 was analyzed by an X-ray
diffraction method. Thereby, it was found that the film 1 contained
hard amorphous carbon, Fe.sub.4N, Fe.sub.3C, martensite, and
Fe.sub.3O.sub.4.
[0092] As mentioned previously, since the film 1 contains Fe.sub.4N
which has a structure denser than that of Fe.sub.2N, the film 1 has
strength higher than that of the initial film 100.
Comparative Example
[0093] A process similar to that of the above-mentioned example was
performed except that a water-soluble release agent was used
instead of the oil-based release agent, and thereby a film
(hereinafter referred to as "the comparison film") was
produced.
[0094] Note that the water-soluble release agent differs from the
oil-based release agent in not preventing the initial film 100 from
being exposed to water and air.
[0095] In other words, the comparison film was produced by
intermittently heating the initial film 100 under an oxidizing
atmosphere.
[0096] Mapping analysis of the comparison film was performed using
the EPMA, similarly to the film 1.
[0097] FIG. 6 shows a result of the mapping analysis of the
comparison film with the EPMA. FIG. 6(a) shows carbon present in
the comparison film, and FIG. 6(b) shows sulfur present in the
comparison film.
[0098] As shown in FIGS. 6(a) and 6(b), in a carbon film of the
comparison film, sulfur is distributed in only a fraction thereof.
At this time, the sulfur-diffusion ratio in the carbon film of the
comparison film is considered to be 5%.
[0099] Thus, the comparison film has the sulfur-diffusion ratio
smaller than that of the initial film 100, and has a friction
coefficient larger than that of the initial film 100. Therefore,
the comparison film has the mold-release resistance larger than
that of the initial film 100.
[0100] As mentioned above, it became clear that the film according
to the present invention was produced by intermittently heating the
initial film under the non-oxidizing atmosphere.
[0101] Moreover, it became clear that the film according to the
present invention contained hard amorphous carbon, Fe.sub.4N,
Fe.sub.3C, martensite, and Fe.sub.3O.sub.4, and that the
sulfur-diffusion ratio in the carbon film was over 50%.
[0102] The mapping analysis was performed using the EPMA in order
to find the sulfur-diffusion ratio in the carbon film, but a method
therefore was not limited thereto as long as the sulfur-diffusion
ratio in the carbon film could be found.
[0103] Moreover, the X-ray diffraction method was used for
identifying materials present in the film, but a method therefore
was not limited thereto as long as the materials present in the
film could be identified.
INDUSTRIAL APPLICABILITY
[0104] The present invention is applied to a film formed on the
surface of an iron-based material, and to a method for
manufacturing the film.
REFERENCE SIGNS LIST
[0105] 1: film [0106] 10: diffusion layer [0107] 20: nitrogen
compound layer [0108] 30: sulfurized layer [0109] 40: carbon film
[0110] 41: hard amorphous carbon [0111] 42: nano-carbon [0112] 43:
fullerene [0113] 100: initial film [0114] 110: diffusion layer
[0115] 120: nitrogen compound layer [0116] 130: sulfurized layer
[0117] 140: carbon film [0118] 141: hard amorphous carbon [0119]
142: nano-carbon [0120] 143: fullerene
* * * * *