JPS61204367A - Production of tin coated stainless steel - Google Patents

Abstract

PURPOSE:To obtain a TiN coated stainless steel with an easy atmosphere adjustment without supplying N from the outside by subjecting a stainless steel as a material to be treated to a Ti coating treatment in which N in said steel is utilized as an N source then subjecting the steel to a heating treatment. CONSTITUTION:The base plate metal 12 consisting of the stainless steel contg. >=0.05%, more preferably >=0.20N and installed in the lower part and a target 11 consisting of a Ti plate is installed in the upper part. The entire part is contained in a vacuum vessel 13. The Ti is then sputtered by using the Ar ions to be supplied from, for example, an Ar supply source 15 into the vessel 13 by applying a high-frequency electric field from an external power source 14 to deposit the Ti on the metal 12. The resultant Ti film is heated to a pre scribed temp. in a vacuum vessel, etc. to diffuse the N and Ti, by which the TiN ceramic coating film is formed. The degree of the vacuum in the vessel 13 is set at 1X10<-7>-3X10<7> Torr and the impressed voltage is set at 2kV.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application) The present invention relates to a method for producing TiN-coated stainless steel, particularly a method for producing TiN-coated stainless steel.
The present invention relates to a method for producing TiN-coated stainless steel using a reactive sputtering method in which TiN is produced on the surface of a treated article.

(Prior Art) Ceramic coating films as mechanical materials are expected to be used in many fields in the future due to their excellent properties. However, just as there are many types of ceramic coatings, each with different characteristics, the current state of affairs is that each coating has its own unique manufacturing methods.

For example, TiN coating film is currently being used not only as a material for nuclear fusion reactors but also for other applications due to its excellent properties as a wear-resistant and corrosion-resistant material or as a material exhibiting a golden color. However, the TiN coating method involves sputtering the article while supplying both ill co-coating and N from an external source. According to the natural sputtering method, N2
Sputtering is performed using Ti as a target material in an atmosphere containing Ti.

(Problems to be Solved by the Invention) As described above, in the conventional method of producing a TiN coating film by reactive sputtering, a Ti target material is used and N2 is supplied from the atmosphere, so atmosphere adjustment is particularly required. This method was difficult, and there were many operational problems, such as the need to constantly adjust the N2 content in the atmosphere within a certain range during sputtering.

Therefore, the essential object of the present invention is to provide a method for forming a TiN ceramic coating film that does not require external supply of N as described above, and in particular, a simple reaction process that facilitates atmosphere adjustment. An object of the present invention is to provide a method for forming a TiN ceramic coating film using a natural sputtering method.

Furthermore, another specific object of the invention is to provide a method for producing a stainless steel with a TiN coating, in particular a TiN coating, by reactive sputtering.

(Means for Solving the Problems) The present inventor has been conducting various research on the TiN ceramic coating method using the reactive sputtering method, and found that when treating stainless steel, it is necessary to supply N2 from the atmosphere. Rather, the present invention was completed based on the discovery that a surface layer with excellent properties could be formed by utilizing N in the steel and Ti precipitated by Ti sputtering.

Therefore, in a broad sense, the gist of the present invention is a method for manufacturing metal nitride-coated stainless steel using an internal N source, and more specifically, the gist of the present invention is a method for manufacturing metal nitride-coated stainless steel using an internal N source. This method of manufacturing TiN-coated stainless steel is characterized in that the article to be treated is coated with Ti to utilize nitrogen in the stainless steel, and then heat treated. When Nb, Ta, etc. are used instead of Ti, corresponding metal nitride coatings can be obtained.

Further, in one aspect of the present invention, the article to be treated is made of stainless steel, and the article to be treated is treated in an atmosphere substantially free of nitrogen in order to utilize nitrogen in the stainless steel as a nitrogen source. This is a method for producing TiN-coated stainless steel using a reactive sputtering method, which is characterized in that an article is subjected to Ti sputtering treatment and then heat treated.

Note that "Ti coating treatment" refers to applying Ti to the surface of the article to be treated by appropriate means such as sputter plating or vacuum evaporation.
A treatment method for coating T by a subsequent heat treatment.
It includes treatments in general that provide a Ti-containing film that can be diffused onto the surface of an article to be treated. Furthermore, "Ti sputtering treatment" is a sputtering treatment method in which Ti is sputtered and deposited on the surface of an article to be treated, in which Ti is used as a target material and accelerated ions are bombarded with it to generate sputtering. This is a treatment method in which this is deposited on the surface of an article to be treated placed near the cathode.

The stainless steel constituting the article to be treated has an N content of 0.05% or more, preferably 0.20% or more, and is generally an austenitic stainless steel.

In the present invention, when Ti coating is performed using the sputtering method, unlike the conventional sputtering method, only the Ti is deposited on the surface of the article to be treated by the spucking process.
After that, heat treatment is performed at an appropriate temperature in an inert gas atmosphere such as Ar, which is unaffected by the atmosphere, or under vacuum to diffuse the Ti deposited on the surface into the interior, and at the same time, the N in the steel is transferred to the surface part. It is necessary to diffuse and combine the two to form TiN on the surface portion. In a preferred embodiment, such heat treatment is performed at 900-1100°C for 3 minutes to 1 hour. If the heating temperature exceeds 1100° C., the mechanical properties of the base material stainless steel may deteriorate, so care must be taken.

(Operation) To further explain the present invention with reference to the accompanying drawings, FIG. 1 is a schematic explanatory diagram of a reactive high frequency sputtering apparatus 10.

In the figure, the target grain l of the Ti plate is placed on the top, and the substrate metal 12 of stainless steel, which is the article to be processed, is placed on the bottom, and the whole is housed in a vacuum container 13. In the illustrated example, Ti is sputtered using argon ions supplied into the vacuum vessel 13 from the Ar supply source 15 to deposit Ti on the metal substrate. These are the magnet, vacuum gauge and shutter. In order to produce a high-purity coating film, it is necessary to apply a negative bias voltage of about 1,500 V to the substrate material. Further, the Ti surface of the target material may be subjected to sputter cleaning treatment as a pretreatment for about 10 minutes to remove impurities.

Generally, in the apparatus shown in Fig. 1, the degree of vacuum is l Xl
0-'~3Xl0-')-JL/, the applied voltage is 2KV. At this time, the Ti precipitation rate was approximately 200
It is person/sin.

The Ti film thus obtained is then heated to a predetermined temperature in a vacuum furnace (not shown) or the like, and subjected to nitrogen and Ti diffusion treatment to form a TiN ceramic coating film.

Next, the present invention will be further explained in connection with examples.

Examples After surface cleaning austenitic stainless steel whose steel composition is shown in Table 1, the equipment shown in Figure 1 was used to clean the surface of the austenitic stainless steel.
Reactive sputtering was performed in an Ar gas atmosphere containing no 2. The processing conditions at this time were as follows.

Argon gas pressure: 4 XlO-' Torr Total pressure: 4 XlO-' Torr Bias voltage -200V Voltage and current during discharge: 2 KV, 0.22 A Film thickness produced: 1000 Next, the Ti spunter thus obtained The treated stainless steel was heat treated.The heating temperature and heating time were varied as follows, and the diffusion behavior of nitrogen in the steel was investigated by sputter etching.

Heating temperature: 600 to 1000°C Heating time: 5 to 60 minutes Table 1 Figure 2 shows the results of the Ti spaft treatment for steel No. 1 in Table 1, followed by heat treatment at 1000°C for 30 minutes under vacuum. This is an example of elemental analysis using the sputter etching method of the ceramic coating film obtained when the ceramic coating was prepared.In particular, it can be seen that a TiN film is formed on the outermost surface.

The color tone was golden.

Figure 3 (fat) is an example of elemental analysis of steel No. 2 sample as it was treated with Ti sputtering before heat treatment was started, and Figure 3 (fat) is an example of elemental analysis after heat treatment at 1000°C for 15 minutes. .

It can be seen from FIG. 3 (al) that the surface of the article to be processed is almost covered with sputtered Ti.

Almost no N is detected on the surface. In the figure, the horizontal axis shows time (minutes), but this is because the elemental analysis is performed using the sputter etching method, and it is proportional to the depth from the surface. In a relationship, 100 minutes is 1500
equivalent to a person.

It can be seen that in the case of Fig. 3, the diffusion of N2 to the surface and Ti in the steel progresses, and the surface coating layer is essentially composed of TiN as in Fig. 2. . This shows that TiN was formed on the surface in an extremely short time compared to the steel No. 1 with a low N content shown in FIG. Moreover, at this time, the surface of the article to be treated had a golden color. A color tone that was sufficiently vivid to be used for decorative purposes was obtained.

In the above, we have described the case where reactive sputtering is used, but in addition to this, Ti is coated on the surface by a chemical method or vacuum evaporation method, and then by heat treatment, N2 is diffused from inside the stainless steel. Ti on the surface
It is also possible to form N in applications.

Furthermore, it is also possible to form a nitride coating of a string metal by the above-described method using Nb, Zr, or other metals having bonding properties with N, not limited to Ti, as a coating source. The fields of application are extremely wide and the industrial value can be said to be extremely large.

[Brief explanation of drawings]

Figure 1 is a schematic diagram of an apparatus for performing reactive sputtering according to the present invention. Figure 2 is a schematic diagram of an apparatus for performing reactive sputtering according to the present invention. Figure 2 is a diagram showing ordinary stainless steel treated with Ti sputtering according to the present invention and then heated at 1000°C for 30 minutes. Graph showing an example of elemental analysis of the coating layer; and Figure 3 (al
and Fig. 3 (bl is for stainless steel with increased N content immediately after Ti sputtering and at 1000°C).
2 is a graph showing an example of elemental analysis after heat treatment for 15 minutes. 10: Reactive high frequency sputtering device 11: Target 12: Substrate metal 13: Vacuum container 14: External power source 15: ^r Supply source Applicant Nippon Stainless Co., Ltd. Agent Patent attorney Akira Hirose - Mo1 Figure 1q: N-7 Coo #2 (tA) #3 concave (#32<b)

Claims (5)

[Claims] (1) TiN-coated stainless steel, characterized in that the article to be treated is made of stainless steel, and the article to be treated is coated with Ti so as to utilize nitrogen in the stainless steel as a nitrogen source, and then heat treated. manufacturing method. (2) The method according to claim 1, wherein the article to be treated is subjected to Ti sputter treatment in an atmosphere substantially free of nitrogen by a reactive sputtering method. (3) The method according to claim 1 or 2, wherein the stainless steel constituting the article to be treated has a N content of 0.05% or more. (4) Claim 1, wherein the stainless steel constituting the article to be treated is austenitic stainless steel;
The method according to item 2 or 3. (5) The stainless steel that constitutes the article to be treated is austenitic stainless steel, and after Ti sputtering treatment
Heat treatment at a temperature of 0 to 1100°C for 3 minutes to 1 hour,
A method according to any one of claims 2 to 4.