KR19980066845A - Aluminum head drum for video cassette recorder with protective layer and method for forming protective layer - Google Patents

Abstract

FIELD OF THE INVENTION The present invention relates to an aluminum head drum for use in a video cassette recorder (VCR) and a method for forming a protective layer thereof, wherein the aluminum is improved by coating a non-magnetic protective layer of sufficient thickness and hardness on the surface of the aluminum head drum. To provide a head drum.

The protective layers of titanium (Ti) and titanium nitride (Ti ₂ N, TiN, TiN ₂ ...) are manufactured by hollow-cathode-deposition (HCD) ion plating and have a thickness of 0.3 µm to 1.5 µm, and diamond The protective layer of phase carbon (DLC) is prepared by plasma-enhanced chemical vapor deposition (PECVD) and has a thickness of 0.3 μm to 2.0 μm. Each protective layer has a variable mechanical hardness, which has a maximum value in the area of the protective layer in contact with the surface, and gradually decreases to have a minimum value in the area of the protective layer that comes into contact with the video tape. The micro-Vickers hardness of the protective layer region in contact with the video tape is 1.5 to 2.0 times greater than that of the magnetic material on the video tape.

Description

Aluminum head drum for video cassette recorder with protective layer and method for forming protective layer

FIELD OF THE INVENTION The present invention relates to video cassette recorders (VCRs), in particular protection of titanium (Ti) and titanium nitride (Ti ₂ N, TiN, TiN ₂ ) or diamond-like carbon (DLC) on the surface. An improved aluminum head drum for a VCR having a layer and a method for forming the protective layer thereof.

As is well known, one of the main roles of a VCR head drum is to provide stability to the tape without damaging or adversely affecting the magnetic tape traveling along a defined path in the VCR. In order to satisfy such a role, the surface of the head drum in contact with the traveling tape is designed in the following manner. That is, the surface of the head drum is smooth, but macroscopically, but in detail, it is designed such that a plurality of reliefs are provided along a direction perpendicular to the axis of rotation of the head drum to reduce friction between the surface of the head drum and the tape. On the other hand, another design requirement is to protect the information recorded on the tape, so that the head drum is usually made of nonmagnetic material.

To date, head drums have been produced by diecasting aluminum alloys, such as Al-Si, Al-Cu or variants thereof. On the surface of the head drum manufactured by die casting of such an aluminum alloy, a layer of aluminum oxide (Al ₂ O ₃ ) having a thickness of several nm is formed. This Al ₂ O ₃ layer is in physical contact and interaction with the lubrication and magnetic layers of the tape.

Since the Al ₂ O ₃ layer formed on the surface of the head drum has an insufficient thickness, that is, it is too thin, the mechanical properties of the Al ₂ O ₃ layer are greatly influenced by the mechanical properties of the aluminum alloy constituting the head drum. Will receive. In other words, the effect of the Al ₂ O ₃ layer can be substantially ignored, so the overall mechanical properties of the aluminum head drum surface can be regarded as the mechanical properties of the surface made of aluminum alloy only. The mechanical hardness and hence the wear resistance of the aluminum head drum is further adversely affected by the pores that occur during die casting of the aluminum head drum.

Since the needle bed powder in the magnetic layer such as γ-Fe ₂ O ₃ , Fe, etc. has a higher mechanical hardness than the aluminum alloy shown in Table 2 below, during normal operation of the VCR, the powder may be scratched against the aluminum head drum surface. In addition to causing abrasion, it is lodged on the aluminum head drum surface. In addition to causing scratches on the surface of the tape, the magnetic powder embedded in the surface forms a layer on the surface of the aluminum head drum when sufficient amount is accumulated on the surface of the aluminum head drum, and the formed magnetic powder layer is thus taped. Magnetically affects the information stored in the image quality.

In addition, since the aluminum head drum is designed in consideration of the aerodynamic and adhesive properties between the aluminum head drum surface and the tape in order to give stability to the running tape, for example, the wear of the aluminum head drum surface of the fine aluminum head of about 0.3 μm is also required. The drum may not be able to fulfill the basic purpose described above.

In addition, wear and tear of the tips of the relief provided on the head drum surface may increase the contact area between the tape and the aluminum head drum, which may further accelerate wear. If this wear persists, the VCR's performance will be adversely affected, causing a sudden image tremor or interruption of the VCR's operation.

Examples of methods that can be used to solve this problem include mechanical hardness than magnetic powder of the magnetic layer of the tape on the aluminum head drum surface that comes into contact with the tape, as disclosed in Japanese Patent Laid-Open Nos. 4-209353 and 4-126459. Some forms a protective layer of a large material. According to Japanese Patent Laid-Open No. 4-209353, a first protective layer made of titanium (Ti) having a thickness of 0.1-0.3 μm is formed, followed by a second protective layer made of titanium nitride (TiN) having a thickness of 0.5-0.7 μm. This can protect the aluminum head drum surface brought into contact with the tape. On the other hand, according to Japanese Patent Laid-Open No. 4-126459, the above problems can be solved by forming diamond-like carbon (DLC) on the aluminum head drum surface which comes into contact with the tape. However, these methods have a number of drawbacks, one of them being titanium (Ti) and titanium nitride (TiN) or diamond phase carbon (DLC), although these methods can protect the aluminum head drum surface. The protective layer cannot protect the tape. Since the material from which the protective layer is made has a higher mechanical hardness than the magnetic material on the tape, the protective layer adversely affects the physical properties of the tape when it comes into contact with the tape, thereby damaging the image quality.

It is therefore an object of the present invention to provide an aluminum head drum for an improved video cassette recorder (VCR) by coating a nonmagnetic protective layer having sufficient thickness and hardness on the surface of the aluminum head drum.

Another object of the present invention is to provide a protective layer on the aluminum head drum surface that does not damage or adversely affect the integrity of the video tape and the information recorded on the tape.

Another object of the present invention is to provide an improved aluminum head drum having high durability against long term use and / or sudden environmental changes.

Another object of the present invention is to provide a method of forming the above protective layer on the aluminum head drum surface.

An aluminum head drum for a video cassette recorder (VCR) provided according to an embodiment of the present invention has a protective layer coated on its surface, and the protective layer comprises diamond-like carbon (DLC) having a thickness of 0.3 μm to 2.0 μm. And have a variable mechanical hardness, the mechanical hardness having a maximum value in the area of the protective layer in contact with the surface of the head drum, and gradually decreasing to a minimum value in the area of the protective layer in contact with the video tape. It is done.

Plasma-enhanced chemical vapor deposition (PECVD) for forming a protective layer of diamond-like carbon (DLC) on an aluminum head drum for a video cassette recorder provided according to another embodiment of the present invention is:

(a) installing an aluminum head drum in a reactor comprising an aluminum head drum holder, wherein at least 10^-4Creating a high vacuum of Torr and checking for any leaks; (b) Heating the reactor to a desired temperature of 80 ° C. to 150 ° C. at about 0.07 Torr to 0.4 Torr while flowing an inert gas, and also preheating the aluminum head drum holder to a desired temperature of 80 ° C. to 150 ° C .; (c) 0.04 mW / cm for 5-30 minutes in the aluminum head drum in the presence of the inert gas after reaching the desired temperature.²To 2W / cm²Cleaning the aluminum head drum surface by striking the plasma at a high frequency (RF) power density of; (d) after plasma cleaning, starting to flow the feed gas mixture comprising methane while reducing the inert gas flow; (e) a temperature of 120 ° C. to 200 ° C. and 0.5 W / cm²To 0.2W / cm²Forming a diamond-like carbon (DLC) protective layer on the surface of the aluminum head drum under a high frequency (RF) power density of; (f) stopping the flow of the feed gas mixture, removing RF-power, and cooling the aluminum head drum with the diamond-like carbon (DLC) protective layer under a flow of inert gas; (g) recovering the aluminum head drum with the diamond-like carbon (DLC) protective layer for inspection and testing.

An aluminum head drum for a video cassette recorder (VCR) provided according to another embodiment of the present invention has a protective layer coated on its surface, the protective layer being 0.3 μm to 1.5 μm thick titanium (Ti) and nitrided It contains titanium (Ti ₂ N, TiN, TiN ₂ ) and has a variable mechanical hardness, which has a maximum value in the area of the protective layer mainly made of titanium (Ti), and is mainly nitrided in contact with the video tape. It is characterized in that it has a minimum value in the region of the protective layer made of titanium (TiN ₂ ).

Hollow-cathode which forms a protective layer of titanium (Ti), titanium nitride (Ti ₂ N) and titanium nitride (TiN ₂ ) on an aluminum head drum for a video cassette recorder provided according to another embodiment of the present invention. Deposition (HCD) ion plating method:

(a) 10^-4Torr to 10^－6Creating a high vacuum of Torr and checking for any leaks; (b) Heating the aluminum head drum to a desired temperature of 150 ° C. to 250 ° C. while introducing an inert gas; (c) 40 mW / cm after reaching the desired temperature²To 200mW / cm²Cleaning the surface of the aluminum head drum by applying a high frequency (RF) power density of a to cause a glow discharge; (d) 10^－3Torr to 10^-2Vacuum state of Torr and 10 mW / cm²To 150mW / cm²Forming a titanium (Ti) protective layer on the aluminum head drum surface using a hollow-cathode-deposited (HCD) electron gun and a titanium (Ti) target under a high frequency (RF) power density or a direct current power density of; (e) After forming the titanium (Ti) protective layer, nitrogen gas (N₂Starting to feed a feed gas mixture comprising₂N, TiN, TiN₂Form a protective layer, and the nitrogen gas (N)₂) Gradually increased from 100 sccm to 1,000 sccm so that titanium (Ti)₂To react with titanium nitride (Ti₂N, TiN, TiN₂Forming); (f) discontinuing the feed gas mixture, stopping the operation of the electron gun, and cooling the aluminum head drum having a protective layer of titanium (Ti) and titanium nitride (TiN) under a flow of inert gas. ; (g) the titanium (Ti) and titanium nitride (Ti)₂N, TiN, TiN₂And recovering the aluminum head drum with a protective layer of c) for inspection and testing.

1 shows the deposition rate of a protective layer of diamond-like carbon as a function of bias voltage.

FIG. 2 shows the micro-Vickers hardness of a protective layer of diamond-like carbon as a function of deposition time.

3 shows the coating conditions and micro-Vickers hardness of a protective layer of titanium and titanium nitride as a function of deposition time.

4 shows the change in compressive stress of a diamond-like carbon layer as a function of layer thickness.

5 shows the effect of an acceleration mode test and a normal operation test on the relief of a head drum surface without a protective layer of the present invention.

6 shows the effect of an acceleration mode test and a normal operation test on the relief of a head drum surface with a protective layer of titanium nitride.

FIG. 7 shows the effect of an acceleration mode test and a humidity test on the relief of a head drum surface with a protective layer of diamond-like carbon. FIG.

These and other objects and features of the present invention will become apparent from the following description of the preferred embodiments with reference to the accompanying drawings.

According to the present invention, a protective layer comprising titanium (Ti) and titanium nitride (TiN) or diamond-like carbon (DLC) is provided on the aluminum head drum surface of the VCR.

Diamond-like carbon (DLC) as used herein means a three-dimensional array of carbon atoms with short range order similar to that observed in diamond structures. Here, each carbon atom is surrounded by four other atoms, but unlike the diamond structure, there is no long range order. In other words, the units of the structure are not repeated regularly. Table 1 also shows the dielectric, chemical, mechanical and optical properties of diamond and diamond-like carbon.

Table 1: Properties of Diamond and Diamond Carbon

Diamond DLC Crystal structure Cube (sp ³ ) amorphous combination of sp ³ , sp ² , sp ¹ , density 3.51 1.8-2.0 Hardness (Vickers, kg / mm ² ) 7,000-10,000 900-3,000 Coefficient of friction 0.03-0.07 0.005-0.05 Refractive index 2.42 1.8-2.2 Permeability UV-VIS-IR VIS IR Optical gap (eV) 5.5 2.0-3.0 Resistivity (! Cm) a10 ¹⁶ 10 ¹⁰ -10 ¹³ Dielectric constant 5.7 4-9

As can be seen from Tables 2 and 3, the above-mentioned protective layer materials, i.e. titanium nitride and DLC, have higher hardness than aluminum alloys, have good separation when in contact with other materials, and have a low coefficient of friction for video tape. Have DLC has the lowest coefficient of friction among the four protective layer materials listed in Table 3.

Table 2: Micro-Vickers Hardness of Various Materials

(Measurement depth is less than 0.5m)

material Micro-Vickers Hardness (kg / mm ² ) Al 16 Al-Cu 100 Al-Si 55 Ti 1,000-1,300 TiN 1,500-2,000 TiC 2,400-2,700 γ-Fe ₂ O ₃ 560 DLC 2,800 Polycrystalline Al ₂ O ₃ 1,600-1,800

Table 3: Friction Coefficients of Various Materials *

material Coefficient of friction Polycrystalline Al ₂ O ₃ 0.35 Ti 0.29 TiN 0.30 DLC 0.25

The coefficient of friction for each material was calculated using the change in tape tension before and after the 80th friction of the tape on the material layer surface.

A protective layer of diamond-like carbon (DLC) is formed on the surface of the aluminum head drum by plasma-enhanced chemical vapor deposition (PECVD), which plasma-enhanced chemical vapor deposition (PECVD):

(a) installing an aluminum head drum in a reactor comprising a die cast aluminum head drum holder, wherein at least 10^-4Creating a high vacuum of Torr and checking for any leaks; (b) Heating the reactor at a desired temperature of from about 0.07 Torr to 0.4 Torr, for example from about 80 ° C. to 150 ° C., while introducing an inert gas such as argon (Ar), and also at a desired temperature, ie 80 ° C. Preheating the aluminum head drum holder to 150 ° C .; (c) after reaching the desired temperature, 0.04 mW / cm in the aluminum head drum for 5-30 minutes in the presence of the inert gas, for example argon (Ar).²To 2W / cm²Cleaning the die cast aluminum head drum surface by striking the plasma at a high frequency (RF) power density of; (d) after plasma cleaning, starting to introduce a feed gas mixture comprising methane while reducing the inflow of inert gas; (e) a temperature of 120 ° C. to 200 ° C. and 0.5 W / cm²To 0.2W / cm²Forming a diamond-like carbon (DLC) protective layer on the surface of the aluminum head drum under a high frequency (RF) power density of; (f) stopping the inlet of the feed gas mixture, removing RF-power, and cooling the aluminum head drum with the diamond-like carbon (DLC) protective layer under a flow of inert gas; (g) recovering for inspection and testing of the aluminum head drum having the diamond-like carbon (DLC) protective layer.

1 shows the deposition rate of a protective layer of diamond-like carbon as a function of bias voltage, and FIG. 2 shows the micro-Vickers hardness of the protective layer of diamond-like carbon as a function of deposition time. . As shown in Figures 1 and 2, the energy to form a diamond-like carbon (DLC) coating on the aluminum head drum surface and the Vickers hardness of the coated protective layer decrease with deposition time. This is because a large amount of energy is required to adhere the diamond-like carbon (DLC) coating to the aluminum head drum surface to provide a very hard diamond-like carbon (DLC) coating. However, once the original diamond-like carbon (DLC) coating has been provided on the aluminum head drum surface, less energy is needed to form additional coatings on the original diamond-like carbon (DLC) coating, thus providing additional coating. As the energy to form is reduced, the micro-Vickers hardness of the formed coating is reduced. The micro-Vickers hardness of the diamond phase carbon (DLC) coating and the energy for forming the diamond phase carbon (DLC) coating are approximately proportional to each other. In the formation of a diamond-like carbon (DLC) coating protective layer, the energy for forming the diamond-like carbon (DLC) coating is gradually reduced to relieve internal compressive stress, which is in contact with the magnetic material on the tape to protect the coating. The micro-Vickers hardness of the layer lasts until approximately the same size as that of the magnetic material on the tape. If the compressive stress in the protective layer is too large to be processed, surface cracks may occur. In the case of a diamond-like carbon (DLC) coated protective layer, as shown in FIG. 2, the micro-Vickers hardness is determined from the magnetic material on the video tape from 3,000 kg / mm ² when the first coating is in contact with the aluminum head drum surface. It decreases to 1,000 kg / mm ² at the time of contact. The micro-Vickers hardness of the diamond-like carbon (DLC) coated protective layer in direct contact with the video tape was deposited at a rate of 5 × 10 ⁻³ μm / min by applying a bias voltage of about 5000 volts as shown in FIG. 1. If so, it is 1.5 to 2.0 times larger than that of the magnetic material on the video tape.

A protective layer of titanium (Ti) and titanium nitride (Ti ₂ N, TiN, TiN _{2 ...} ) is formed on the aluminum head drum by hollow-cathode-deposition (HCD) ion plating. Cathode deposition (HCD) ion plating is:

(a) 10^-4Torr to 10^－6Creating a high vacuum of Torr and checking for any leaks; (b) Heating the aluminum head drum to a desired temperature, for example 150 ° C. to 250 ° C., while introducing an inert gas such as argon (Ar); (c) 40 mW / cm after reaching the desired temperature²To 200mW / cm²Cleaning the surface of the aluminum head drum by applying a high frequency (RF) power density of a to cause a glow discharge; (d) 10^－3Torr to 10^-2Vacuum state of Torr and 10 mW / cm²To 150mW / cm²Forming a titanium (Ti) protective layer on the aluminum head drum surface using a hollow-cathode-deposited (HCD) electron gun and a titanium (Ti) target under a high frequency (RF) power density of; (e) After forming the titanium (Ti) protective layer, nitrogen gas (N₂Introducing a feed gas mixture comprising a) to form a protective layer of titanium nitride (TiN), the nitrogen gas (N₂) Gradually increased from 100 sccm to 1,000 sccm so that titanium (Ti)₂To react with titanium nitride (Ti₂N, TiN, TiN₂Forming a); (f) stopping the flow of the feed gas mixture, stopping the operation of the electron gun, and in the flow of an inert gas, the titanium (Ti) and titanium nitride (Ti)₂N, TiN, TiN₂Cooling the aluminum head drum with a protective layer of; (g) recovering for inspection and testing of the aluminum head drum having a protective layer of titanium and titanium nitride.

In general, when titanium (Ti) and nitrogen (N ₂ ) are molecularly equilibrated, the micro-Vickers hardness of the protective layer is optimal. By adjusting the titanium (Ti) to nitrogen (N ₂ ) ratio, the compressive stress in the protective layer can be controlled according to the micro-Vickers hardness of the protective layer. The micro-Vickers hardness of the protective layer region in direct contact with the video tape is 1.5 to 2.0 times greater than that of the magnetic material on the video tape.

3 shows the coating conditions and micro-Vickers hardness of the protective layer of titanium and titanium nitride as a function of deposition time. In this way, when the protective layer is formed of titanium nitride, the deposition rate is not significantly affected by the nitrogen gas (N ₂ ). Under the above conditions, the deposition rate is about 0.04 μm / min, and FIG. 3 shows a case where the thickness of the titanium and titanium nitride protective layers is about 1-2 μm.

If the protective layer is too thin, the mechanical properties of the protective layer will be primarily influenced by the mechanical properties of the aluminum head drum made of aluminum alloy, in this case the aluminum head drum as seen in the case of the Al ₂ O ₃ layer. The surface may not be adequately protected. On the other hand, when the protective layer is too thick, surface cracks may occur when the compressive stress in the protective layer becomes too large and the temperature or the like changes.

The optimum thickness of the titanium and titanium nitride protective layers was in the range of 0.3-1.5 μm; The optimum thickness of the diamond-like carbon (DLC) protective layer was in the range of 0.3-2.0 μm. The optimum thickness represents the area where the compressive stress remains nearly constant with respect to the layer thickness. 4 shows the variation of the compressive stress of a protective layer made of diamond-like carbon (DLC) as a function of layer thickness.

In order to evaluate the reliability of the head drum having a protective layer of titanium and titanium nitride or diamond-like carbon (DLC), the following test was carried out.

(1) Perform an acceleration mode test that continuously operates the VCR in fast forward, backward, fast forward search, and reverse seek modes within 30 seconds, with 7 seconds for fast forward mode, 7 seconds for reverse mode, and fast forward search mode. Lasts 8 seconds and reverse search for 8 seconds.

(2) Perform normal operation test, ie operate the VCR in play mode.

(3) Perform the humidity test by operating the VCR in play mode at 30 ° C and 70% humidity.

The results obtained in this way were compared with those obtained from similar tests conducted with a VCR with conventional head drums.

The effect of the acceleration mode test and the normal operation test on the relief provided on the head drum surface was observed using a surface roughness tester of KOSAKA (Surfcorder SE-300).

Example 1

The reliability of the conventional aluminum head drum was evaluated according to the reliability evaluation procedure described above, and the result is shown in FIG. In particular, FIG. 5A shows roughness test data of a conventional head drum surface before a reliability test; 5B shows surface roughness data after a 1,000 hour acceleration mode test, and FIG. 5C shows surface roughness data after a 1,000 hour normal operation test.

Example 2

A protective layer of 0.8 μm thick titanium and titanium nitride was formed on the aluminum head drum surface using HCD ion plating. The reliability of the aluminum head drum was evaluated according to the reliability evaluation procedure described above, and the results are shown in FIG. In particular, FIG. 6A shows the roughness data of the aluminum head drum surface before the reliability test; 6B shows surface roughness data after a 1,000 hour acceleration mode test, and FIG. 6C shows surface roughness data after a 1,000 hour normal operation test.

Example 3

A protective layer of 0.2 μm thick diamond-like carbon (DLC) was formed on the aluminum head drum surface using plasma-enhanced chemical vapor deposition (PECVD). The reliability of the aluminum head drum was evaluated according to the reliability evaluation procedure described above, and the results are shown in FIG. In particular, FIG. 7A shows the roughness data of the aluminum head drum surface before the reliability test; 7B shows surface roughness data after a 1,000 hour acceleration mode test, and FIG. 7C shows surface roughness data after a 1,000 hour humidity test.

According to the results obtained from the conventional head drum, in the case of the accelerated mode test, the relief provided on the aluminum head drum surface almost disappeared after 200 hours; After 1,000 hours of continuous testing, it disappeared completely as shown in FIG. 5B, and then a lapping process was performed on the aluminum head drum surface. For the normal operation test, the undulations all disappeared from the aluminum head drum surface after a 1,000 hour continuous test as shown in FIG. 5C. According to the results obtained from the humidity test, when observed after 1,000 hours of testing, the surface was covered with a binder-like material (not shown), and as a result, the relief of the head drum surface disappeared. Binder-like material that is believed to originate from the video tape results in increased friction between the video tape and the head drum surface under high humidity. In addition, abrupt VCR shutdown was observed, which is caused by increased tape tension under high humidity conditions due to increased friction between the video tape and the head drum surface.

The results obtained from aluminum head drums with titanium and titanium nitride protective layers show that even after a 1,000 hour acceleration mode test, the ups and downs remain in their initial form as shown in FIG. 6B, unlike in the case of conventional head drums. Similar results were obtained from the humidity test (not shown) and the normal operation test (see FIG. 6C).

Results from acceleration mode tests and humidity tests on aluminum head drums with diamond-like carbon (DLC) protective layers show that even after 1,000 hours of testing, the reliefs continue in their initial form (see FIGS. 7B and 7C). maintain.

While the invention has been shown and described with reference to specific embodiments, those skilled in the art will recognize that various changes and modifications can be made without departing from the scope and spirit of the present invention as defined by the claims.

As described above, the present invention, by coating a non-magnetic protective layer of sufficient thickness and hardness on the surface of the aluminum head drum for video cassette recorder (VCR) to improve the characteristics of the aluminum head drum, It prevents the information recorded on the tape from being damaged or adversely affected, and also increases the durability of the aluminum head drum for long periods of use and / or sudden environmental changes.

Claims (6)

In an aluminum head drum for a video cassette recorder (VCR) having a protective layer coated on its surface, The protective layer includes diamond-like carbon (DLC) having a thickness of 0.3 μm to 2.0 μm and has a variable mechanical hardness, the mechanical hardness having a maximum value in the protective layer region in contact with the surface, and gradually decreasing. And a minimum value in the protective layer region in contact with the video tape. 2. The aluminum head for a video cassette recorder (VCR) according to claim 1, wherein the micro-Vickers hardness of the protective layer region in contact with the video tape is 1.5 to 2.0 times larger than that of the magnetic material on the video tape. drum. As plasma-enhanced chemical vapor deposition (PECVD), which forms a protective layer of diamond-like carbon (DLC) on an aluminum head drum for a video cassette recorder: (a) installing an aluminum head drum in a reactor comprising an aluminum head drum holder, wherein at least 10^-4Creating a high vacuum of Torr and checking for any leaks; (b) Heating the reactor to a desired temperature of 80 ° C. to 150 ° C. at about 0.07 Torr to 0.4 Torr while introducing an inert gas, and further preheating the aluminum head drum holder to a desired temperature of 80 ° C. to 150 ° C .; (c) 0.04 mW / cm for 5-30 minutes in the aluminum head drum in the presence of the inert gas after reaching the desired temperature.²To 2W / cm²Cleaning the aluminum head drum surface by striking the plasma at a high frequency (RF) power density of; (d) after plasma cleaning, starting to introduce a feed gas mixture comprising methane while reducing inert gas flow; (e) a temperature of 120 ° C. to 200 ° C. and 0.5 W / cm²To 0.2W / cm²Forming a diamond-like carbon (DLC) protective layer on the surface of the aluminum head drum under a high frequency (RF) power density of; (f) discontinuing the feed gas mixture, removing RF-power, and cooling the aluminum head drum with the diamond-like carbon (DLC) protective layer under a flow of inert gas; (g) Plasma-enhanced chemical vapor deposition (PECVD) comprising recovering the aluminum head drum with the diamond-like carbon (DLC) protective layer for inspection and testing. In an aluminum head drum for a video cassette recorder (VCR) having a protective layer coated on its surface, The protective layer includes titanium (Ti) and titanium nitride (TiN) having a thickness of 0.3 μm to 1.5 μm and has a variable mechanical hardness, and the mechanical hardness has a maximum value in a protective layer region mainly made of titanium (Ti). And a minimum value in a protective layer region mainly made of titanium nitride (Ti ₂ N, TiN, TiN _2... ) In contact with the video tape. 5. The aluminum head for a video cassette recorder (VCR) according to claim 4, wherein the micro-Vickers hardness of the protective layer region in contact with the video tape is 1.5 to 2.0 times larger than that of the magnetic material on the video tape. drum. As a hollow-cathode-deposition (HCD) ion plating method for forming a protective layer of titanium (Ti) and titanium nitride (TiN) on an aluminum head drum for a video cassette recorder: (a) 10^-4Torr to 10^－6Creating a high vacuum of Torr and checking for any leaks; (b) Heating the aluminum head drum to a desired temperature of 150 ° C. to 250 ° C. while introducing an inert gas; (c) 40 mW / cm after reaching the desired temperature²To 200mW / cm²Cleaning the surface of the aluminum head drum by applying a high frequency (RF) power density of a to cause a glow discharge; (d) 10^－3Torr to 10^-2Vacuum state of Torr and 10 mW / cm²To 150mW / cm²Forming a titanium (Ti) protective layer on the aluminum head drum surface using a hollow-cathode-deposited (HCD) electron gun and a titanium (Ti) target under a high frequency (RF) power density or a direct current power density of; (e) After forming the titanium (Ti) protective layer, nitrogen gas (N₂And start flowing a feed gas mixture comprising₂N, TiN, TiN_2...To form a protective layer, wherein the nitrogen gas (N)₂) Content is gradually increased from 100sccm to 1,000sccm so that titanium (Ti)₂To react with titanium nitride (Ti₂N, TiN, TiN₂Forming a); (f) stopping the inlet of the feed gas mixture, stopping the operation of the electron gun, and cooling the aluminum head drum having the protective layer of titanium (Ti) and titanium nitride (TiN) under the inlet of inert gas; ; (g) Hollow-cathode-deposition (HCD) ion plating method comprising recovering the aluminum head drum having the protective layer of titanium (Ti) and titanium nitride (TiN) for inspection and further testing.