JPS6179760A - Formation of aluminum oxide film by activated reactive ion plating - Google Patents

Abstract

PURPOSE:To form a hard Al2O3 film on a substrate of a metal or the like by reacting Al vapor from an evaporating source with gaseous O2 as a reactive gas in an arc discharge type high vacuum ion plating apparatus. CONSTITUTION:A hard Al2O3 film having >=2000 micro-Knoop hardness is formed on the surface of a substrate such as a steel plate preheated to 500 deg.C by an activated reactive ion plating method using high purity Al as an evaporating source and gaseous O2 as a reactive gas in an arc discharge type high vacuum ion plating apparatus. Conditions during the ion plating include 10kV-500-550mA output of an electron gun, 7-10X10<-5>Torr pressure of gaseous O2, 0.3-0.5kV voltage of the substrate, 40A thermoelectron current and 15-20A ionization current.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming a hard film by ion plating. In recent years, intensive research has been conducted to improve tool performance or extend tool life by forming hard coatings such as TiN or TiC on the surfaces of cutting tools or molds using CVD or PVD methods. has already been put into practical use and is commercially available.

Among these hard coatings, aluminum oxide coatings have excellent wear resistance, heat resistance, corrosion resistance, and oxidation resistance.
Furthermore, compared to TiN, t'tc, etc., raw material costs are low, which is a great advantage in practical application.

In CVD, good results have already been obtained by coating cutting tools with an aluminum oxide film, and this has been put into practical use.

However, in the CVD method, the reaction temperature is 100
Due to the high temperature of 0° C. or higher, the coating base material is currently limited to carbide tools. On the other hand, activated reactive ion plating, which is a type of ion plating, has a T
Hard coatings such as IN and TiC can be easily formed, and if an aluminum oxide coating can be formed by this method, its range of applications will be greatly expanded. however,
There are few reports that hard aluminum oxide coatings have been obtained by activated reactive ion plating, and even in these few studies, the obtained aluminum oxide coatings have a micro-Vickers hardness of 800 to 400, with a micro-Vickers hardness of 20.
A hard aluminum oxide film with a hardness of 00 or higher has not been obtained by the ion plating method so far.

In the present invention, an arc discharge type high vacuum ion plating apparatus is used, At (99°99%) is selected as the evaporation source, 02 is selected as the reaction gas, the substrate is preheated to about 500°C, and the electron gun output is 10. KV -500~550mA
, 02 gas pressure 7~1OXlOTOrr1 substrate voltage 0.
3-0,5 KV, thermionic current 4OA, ionization current 1
A hard aluminum oxide film having a microknoop hardness of 2000 or more is formed on the substrate surface under conditions of 5 to 2 OA. The feature of the present invention is that the ionization current is
The purpose is to set the concentration sufficiently high to 2OA to sufficiently ionize and activate the vaporized aluminum particles and 02 gas molecules, thereby promoting the formation reaction of the aluminum oxide film. In other words, when the ionization current is lower than 15 A, even if the 02 gas pressure and other ~ conditions are appropriate, the reaction between the evaporated aluminum particles and the 02 gas molecules does not proceed sufficiently, and the formed film is The composition of
It is a mixture of unreacted aluminum and aluminum oxide, and sufficient hardness cannot be obtained.

Next, the present invention will be described in detail with reference to Examples.Example 1 A cold rolled steel plate (SPCC) was used as a substrate, polished to a mirror surface, and then ultrasonically cleaned in acetone for testing.

As a pretreatment, argon pressure is applied for 80 minutes under a voltage of 0.8 to 0.4 KV in an argon gas atmosphere of 0.02 Torr, and then the substrate is preheated to 500° C. for 30 minutes.

After that, the electron gun output was 10 KV -500 mA, O
z gas pressure 10 x 1O-5Torr, substrate voltage 0.4
2 KV, thermionic current 40 A s ionization current 20
Ion plating was performed for 60 minutes at A, and the film thickness was 1.
A hard aluminum oxide coating of 37 μm/hardness Hk (10 gr) 3619 was obtained.

Example 2 The substrate, pretreatment, and preheating were as in Example 1. It is similar to

After sono, electron gun output 10 KV -500rnA s
02 gas pressure 10 x 1O-5Torr, substrate voltage 0.
Ion plating was performed for 50 minutes at 84KV, thermionic current 4OA, and ionization current 15A, resulting in a film thickness of 2.62μ.
A hard aluminum oxide coating with m1 hardness Hk (10 gr) 2500 was obtained.

Example 8 The substrate, pretreatment, and preheating are the same as in Example 1.

After sono, electron gun output 10 KV -500mA, 0
2 Gas pressure 7 X 1O-5Torr 1 Substrate voltage 0.35
KV, ion plating was performed for 52 minutes at a thermionic current of 40A and an ionization current of 20A, resulting in a film thickness of 1.82μ.
A hard aluminum oxide coating with m1 hardness Hk (10 gr) 2772 was obtained.

Example 4 The substrate, pretreatment, and preheating are the same as in Example 1.

After that, electron gun output 10 KV -550mA, 02
Gas pressure 10 x 10"l'orr, substrate voltage 0.4
KV, thermionic current 40A1 ionization current 20A 48
Perform ion plating for minutes, film thickness 2.15μm1
A hard aluminum oxide coating with a hardness of Hk (10 gr) 8592 was obtained.

As explained above, the aluminum oxide film forming method of the present invention can be performed by appropriately selecting O2 gas pressure and other conditions.
By setting the ionization current to 15 A to 20 A,
This has the effect of making it possible to form a hard aluminum oxide film with a Microknoop hardness of 2000 or more.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the principle of an arc discharge type high vacuum ion plating apparatus (manufactured by Shinko Seiki). The number ■ in the figure is a carbon heater that heats the sample attached to the substrate holder ■ from the back side. Shanotar ■ is designed to open automatically when the electron gun power source is activated. ■ is an ionization electrode,
A positive voltage is applied to the evaporation source (2) to induce plasma discharge. When a low melting point metal such as aluminum is used as the evaporation source, thermionic electrons necessary for plasma discharge are insufficient, so thermionic electrons are supplied by the thermionic emission power source (2). The amount of thermionic electrons supplied is controlled as thermionic current. Electrons in the plasma are attracted to the positively applied ionization electrode, and their amount is controlled by the ionization current. Figure 1

Claims (1)

[Claims] By activated reactive ion plating, the evaporated metal is aluminum, the reactive gas is O_2, and the electron gun output is 1.
0KV-500~550mA, O_2 gas pressure 7~10x
Hard aluminum oxide with a microknoop hardness of 2000 or more was deposited on the substrate under the conditions of 10^-^5 Torr, substrate preheating of 500°C, substrate voltage of 0.3 to 0.5 KV, thermionic emission current of 40 A, and ionization current of 15 to 20 A. An aluminum oxide film forming method characterized by forming an aluminum oxide film.