JP2005089810A - Grain-oriented silicon steel sheet, its manufacturing method, and pvd treatment device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To manufacture a grain-oriented silicon steel sheet having a TiN film of high heat resistance at a relatively low cost, and to provide a PVD treatment device to be used therefor. <P>SOLUTION: A mixed layer containing Fe, Ti and N is formed on a surface of a finish-annealed grain-oriented silicon steel sheet. A TiN layer of a general formula Ti<SB>X</SB>N<SB>(2-X)</SB>(where, X: 0.2-1.3) except inevitable impurities is formed on the mixed layer. In addition, a face layer consisting of Ti-Me-N (where Me is Si and/or Al) except inevitable impurities and containing 5-70 mass% is formed on the TiN layer. The content of Me in the TiN layer and the face layer is increased from the mixed layer side to a surface part of the face layer. An insulating film containing phosphate and silica can be formed on the face layer. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a unidirectional electrical steel sheet obtained by applying a TiN coating on the surface of a finish annealed unidirectional electrical steel sheet, a manufacturing method thereof, and a PVD processing apparatus that can be suitably used for the manufacture thereof.

  In order to reduce the magnetic properties of unidirectional electrical steel sheets, especially the iron loss value, secondary recrystallized grains are highly accumulated in the (110) [001] orientation by finish annealing and the surface is smoothened. In addition, it is known that it is effective to apply a ceramic film such as TiN to provide tension and to provide insulation (for example, Patent Document 1).

  The hollow cathode method (Hollow Cathode Discharge, HCD) is known for the formation of the TiN film, but the time required for the film formation is long and the generated film tends to deteriorate in a high-temperature oxidizing atmosphere. There is a problem that heat resistance is not sufficient. In addition, when free Ti, O, N, etc. are present in the TiN coating, there is a problem that these elements diffuse into the magnetic steel sheet iron during high-temperature strain relief annealing and deteriorate the magnetic properties, particularly iron loss. is there.

  In order to solve such a problem, for example, in Patent Document 2, when a plurality of ceramic layers are coated on the surface of a unidirectional silicon steel plate, a high bias voltage of −100 V or more is applied to the steel plate as the first coating layer. A means for forming a TiNO film by the hollow cathode method is disclosed.

Japanese Patent Laid-Open No. 11-131252 Japanese Unexamined Patent Publication No. 2002-356751

  However, even with the means described in Patent Document 2, the film adhesion after the strain relief annealing is not sufficient, and therefore there is a problem that it is difficult to sufficiently reduce the iron loss in the state after the strain relief annealing. . Further, since the above means uses two kinds of film forming means, that is, HCD method and magnetron sputtering method, there is a problem that it is too expensive to form the film. An object of the present invention is to propose a unidirectional electrical steel sheet having a TiN-based coating film having a relatively low cost and high heat resistance, a method for producing the same, and a PVD processing apparatus that can be suitably used for the production. .

The unidirectional electrical steel sheet according to the present invention has a mixed layer containing Fe, Ti, and N on the surface of a finish-oriented annealed unidirectional electrical steel sheet, and the general formula Ti _X excluding inevitable impurities on the mixed layer. It has a TiN layer composed of N _(2-X) (where X is 0.2 to 1.3), and further comprises Ti-Me-N (where Me is Si and / or Al) excluding inevitable impurities on the TiN layer, While it has a surface layer containing 5 to 70 mass% of Me, the content of Me in the TiN layer and the surface layer increases as it reaches the surface portion of the surface layer from the mixed layer side. An insulating coating containing phosphate and silica can be provided on the surface layer.

The unidirectional electrical steel sheet is a method of manufacturing a unidirectional electrical steel sheet in which a TiN-based coating is formed on a surface of a finish annealed unidirectional electrical steel sheet by a PVD method. After forming a TiN layer of the general formula Ti _X N _(2-x) (where X: 0.2 to 1.3) except for unavoidable impurities while forming a mixed layer containing Ti and N, Ti- It is made of Me-N (where Me is Si and / or Al) and forms a surface layer containing 5 to 70 mass% of Me. It can be manufactured by increasing as it reaches the part. In this manufacturing method, an insulating film containing phosphate and silica can be formed on the surface layer.

  The unidirectional electrical steel sheet includes an inlet side differential pressure chamber through which a strip is sequentially passed, a PVD coating strip, and an outlet side differential pressure chamber. In the PVD processing apparatus that coats the surface of the strip, the PVD The coating band is constituted by a plurality of coating chambers connected to each other and partitioned by a partition plate, and each of the plurality of coating chambers includes at least one pair of multi-arc discharge portions and at least one across the path of the strip-shaped body. It can be manufactured by using a PVD processing apparatus that includes a plurality of reactive gas introduction holes and that can arrange a target of any composition in the multi-arc discharge section.

  According to the present invention, it becomes possible to produce a unidirectional electrical steel sheet having a TiN-based coating film having a relatively low cost and high heat resistance. In addition, the unidirectional electrical steel sheet obtained by the present invention has a low iron loss value after strain relief annealing and is excellent in the bending adhesion of the coating film. Therefore, if it is used for a winding transformer or the like, it contributes to energy saving. Further, by using the PVD processing apparatus according to the present invention, it becomes possible to continuously and efficiently produce the unidirectional electrical steel sheet having the TiN-based film having high heat resistance.

  The present invention is applied to a finish-oriented unidirectional electrical steel sheet. The unidirectional electrical steel sheet contains 2.5 to 4.5 mass% of Si, has a highly integrated (110) [001] texture, and is manufactured by a known means. The unidirectional electrical steel sheet of the present invention is formed by depositing a TiN-based coating described in detail below on the surface of the finish-annealed unidirectional electrical steel sheet.

  The TiN-based coating has a small thermal expansion coefficient with respect to the ground iron of the unidirectional electrical steel sheet, thereby suppressing the magnetostriction of the unidirectional electrical steel sheet and reducing the power loss during use. In order to fully exhibit the function, it is preferable that the unidirectional electrical steel sheet is in a state in which the surface of the ground iron is exposed, and the TiN-based coating is directly formed on the surface of the ground iron.

  In addition, as for the manufacturing method of the unidirectional electrical steel sheet in which the surface of the ground iron is exposed, any of many proposed methods can be adopted. In addition, the extent of exposure of the ground iron may be such that the iron loss value is not harmed by the presence of a so-called forsterite-based coating. It is sufficient that the finishing degree is so-called smoothing, and the degree may be determined by a necessary iron loss value or the like. In addition, what gave the well-known magnetic domain subdivision process can also be made into the application object of this invention, and, thereby, the fall of a further iron loss can be achieved.

  In the present invention, the TiN-based coating formed on the surface of the unidirectional electrical steel sheet has different functions between the portion of the steel sheet in contact with the ground iron (near the ground iron) and the surface vicinity, In the vicinity of the surface, for example, heat resistance at high temperatures such as during strain relief annealing is increased. In these intermediate portions, the above characteristics change in an inclined manner.

Specifically, as schematically shown in FIG. 1, a base layer 42 of a unidirectional electrical steel sheet has a mixed layer 43 containing Fe, Ti, and N, and unavoidable impurities are removed on the mixed layer 43. It has a TiN layer 44 of the general formula Ti _X N _(2-X) (where X is 0.2 to 1.3), and Ti-Me-N (where Me is Si and / or) except for inevitable impurities on the TiN layer 44. Or Al) and has a surface layer 45 containing 5 to 70 mass% Me. The Me content in the TiN layer 44 and the surface layer 45 gradually increases from the mixed layer 43 side to the surface portion 46 of the surface layer 45.

  The mixed layer 43 is a layer that is inevitably generated when the TiN-based film is deposited by the PVD method, and exists between the ground iron 42 and the TiN layer 44 of the unidirectional electrical steel sheet.

The subsequent TiN layer 44 is of the general formula Ti _X N _(2-X) (where X is 0.2 to 1.3) except for inevitable impurities, and forms the main part of the coating layer formed by the present invention. Stoichiometrically, TiN is a combination of Ti and N in an atomic ratio of 1: 1, but the TiN film formed by the PVD method etc. does not have such a theoretical chemical composition, It has the general formula Ti _X N _(2-X) that contains Ti in excess or in excess of N. In this case, if the content of Ti with respect to N is excessive or too low, for example, during high-temperature strain relief annealing, Ti or N diffuses and penetrates from the generated coating layer into the ground iron electrical steel sheet, resulting in iron loss. Causes the value to decrease. Therefore, the chemical composition of the TiN layer 44 requires that the value of X in the general formula Ti _X N _(2-X) be 0.2 to 1.3. Note that the value of X can be determined using, for example, GDS (Glow Discharge Spectroscopy) or XPS (X-ray Photoelector Spectroscopy) as will be described later.

  The TiN layer 44 preferably has a very high purity at the transition from the mixed layer 43 (hereinafter referred to as “initial TiN layer”). For example, the impurities Si and Al diffuse and penetrate into the ground iron in the process of high-temperature strain relief annealing and cause a reduction in the iron loss value of the product. Therefore, in the initial TiN layer, these elements are each Si. : 0.1 mass%, Al: It is better to limit to 0.1 mass% or less. In order to achieve this purpose, it is desirable to form an initial TiN layer using a high purity Ti target from the mixed layer 43 to a thickness of at least about 0.02 μm. The deposited thickness and composition of the TiN layer (including the initial TiN layer) can be determined using, for example, GDS (Glow Discharge Spectroscopy) or XPS (X-ray Photoelectoron Spectroscopy), as will be described later. .

  On the other hand, the surface layer 45 is made of Ti—Me—N (where Me is Si and / or Al) except for inevitable impurities, and has a Me content of 5 to 70 mass%. The reason why the surface layer of the film is Si and Al-rich is to improve the heat resistance of the TiN-based film to 850 ° C. or higher. If the Me is less than 5 mass% in the surface layer 45, the TiN-based film is likely to deteriorate during strain relief annealing. On the other hand, if the abundance of these elements exceeds 70 mass%, the film oxidation during the strain relief annealing is significant. Becomes brittle. Therefore, the content of Me in the surface layer 45 of the coating is limited to 5 to 70 mass%, preferably 15 to 50 mass%. Note that the content of Me in the surface layer 45 can be obtained, for example, by a depth profile by GDS or XPS as described later.

  The surface layer 45 desirably has a thickness of at least 0.1 μm or more in terms of its function, but if the Si or Al-rich layer thickness is too thick, it becomes brittle after strain relief annealing, and the adhesion of the film is impaired. The thickness is preferably limited to 0.2 μm or less. It should be noted that the thickness and composition of the surface layer 45 can be measured in the same manner as the TiN layer (including the initial TiN layer).

  The Me content in the TiN layer 44 and the surface layer 45 is increased from the mixed layer 43 side to the surface portion 46 of the surface layer. In the mixed layer 43 and the initial TiN layer transferred from there to the TiN layer 44, the Me content is almost zero, but gradually increases in the TiN layer 44 and the surface layer 45, and reaches the maximum at the surface portion 46 of the surface layer. It is preferable to take a value. The increase in Me from the mixed layer 43 to the surface layer 45 should be carried out without causing a local extreme concentration difference, whereby a TiN-based coating is applied to the surface of the grain-oriented electrical steel sheet with good adhesion. It can be held.

2 and 3 respectively show the depth by GDS (Glow Discharge Spectroscopy) near the surface of the unidirectional electrical steel sheet obtained when Me is increased from the mixed layer side to the surface part of the surface layer according to the present invention. It is an example of a profile. As shown here, in the mixed layer 43, the content of Fe decreases and the content of Ti and N increases, and in the transition to the TiN layer 44 (initial TiN layer), Fe, Si and Al Each content of is almost zero. In the TiN layer 44, the N content increases with Ti, indicating that a ceramic according to the general formula Ti _X N _(2-x) is formed except for inevitable impurities. In the surface layer 45, the Ti content is reduced. In the case shown in FIG. 2, Si starts increasing gradually from the middle portion in the thickness direction of the TiN layer 44 and reaches the maximum value on the surface portion of the surface layer 45 in the case shown in FIG. 3.

  As shown here, the boundaries between the base iron 42, the mixed layer 43, the TiN layer 44, and the surface layer 45 are not so critical. In the present invention, as shown in FIGS. 2 and 3, the boundary between the base iron and the mixed layer is mixed with the transition point of Fe content (intersection of the extrapolation line of the Fe intensity line from the base iron side and the mixed layer side). The boundary between the layer and the TiN layer is that the Fe content is substantially zero, and the boundary between the TiN layer and the surface layer is the point where the Ti content starts to decrease (the Ti intensity line from the TiN layer side and from the surface layer side). The intersection of extrapolated lines). The initial TiN layer refers to a range in which the Me content is substantially 0 from the boundary between the mixed layer and the TiN layer.

What is important is that each component in the formed coating changes continuously and does not have discontinuous points of component change. Table 1 shows the mixed layer thickness, TiN layer thickness, initial TiN layer thickness, surface layer thickness, _{X of the} general formula Ti _X N _(2-x) determined from the depth profiles of FIGS. The value of was shown together with the content of Me in the surface layer. Here, the thickness of each layer is obtained by reading from FIG. 2 and FIG. 3, while the content of Me in the surface layer is the strength of each of Al and Si in the outermost surface layer (the portion having a depth of 0 from the surface) as Al, It calculated | required as a total value of what remove | divided with the intensity | strength when content of Si was 100 mass%. Further, the value of X when the TiN layer is represented by the general formula Ti _X N _(2-x) was obtained from the strength change of Ti and N of the TiN layer in FIGS.

  The unidirectional electrical steel sheet with the TiN-based coating on the surface can be used as it is, but an insulating coating 47 can also be formed on it, which can be used as a transformer core. become able to. As the insulating film 47, any of organic, inorganic or organic-inorganic composite systems can be adopted. However, an insulating film containing phosphate and silica improves the insulation of the electrical steel sheet and further provides a tensioning function. It is suitable for imparting.

  In order to produce a unidirectional electrical steel sheet having the TiN-based coating on its surface, first, a unidirectional electrical steel sheet (preferably with the exposed surface of the ground iron) that has been annealed by known means is produced. On the other hand, the mixed layer 43, the TiN layer 44, and the surface layer 45 are formed by multi-arc discharge using a PVD processing apparatus described below. Further, an insulating coating 47 is formed as necessary.

  FIG. 4 is a schematic cross-sectional view showing an example of a PVD coating apparatus that can be suitably used for carrying out the present invention, and FIG. 5 is a partially enlarged explanatory view of a multi-arc discharge section used in the apparatus shown in FIG. is there. As shown here, the PVD processing apparatus of this example includes an inlet side differential pressure zone 10, a PVD coating zone 20, and an outlet side differential pressure zone 30 through which the strip S is sequentially passed, so-called air toe. A TiN-based film or the like can be continuously formed on the surface of the strip S such as a unidirectional electromagnetic steel strip by an air to air method.

  The inlet-side differential pressure zone 10 is configured by arranging differential pressure chambers 13 (13A-13C) with seal rolls 11 (11A-11D) and exhaust ports 12 (12A-12C) on the inlet and outlet sides in series, respectively. Thus, the steel strip S can be introduced into the PVD-coated strip 20 that has been decompressed from the atmosphere. The delivery side differential pressure zone 30 has the same configuration, and the steel strip S can be carried out from the decompressed PVD coating zone 20 to the atmosphere.

  The PVD coating band 20 is partitioned into a plurality of coating chambers (21A to 21D) by partition walls 24 (24A to 24C), and each coating chamber has a coating chamber outer wall 25 as shown in FIGS. A multi-arc discharge section 34 (34A to 34D) and a reaction gas inlet 23 are provided therein. The multi-arc discharge part 34 is provided in a pair of upper and lower sides across the path of the belt-like band S. A power source 29 is provided between the target 26 and the electrode 41, and discharge is performed between the two. The target 26 attached to the coating chamber 21 can have an arbitrary composition, and the atmosphere in each coating chamber 21 is changed in the composition of the gas G introduced from the reaction gas inlet 23 (23A to 23D). Can be controlled freely.

  The covering chamber is provided with a target installation portion that can move the target 26 up and down from the outer wall 25 of the covering chamber, bar magnets 27 and 28 are provided around the top of the target 26, and the magnetic poles of these bar magnets are N poles. It is recommended that the S poles be placed alternately on the circumference. As a result, continuous operation over a long period of time becomes possible, and effects such as uniformization of the cathode surface and fine melting are brought about during arc discharge.

  The partition walls 24 (24A to 24D) for partitioning the respective coating strips may be of a level that prevents the gas flow between the respective coating chambers, and it is not necessary to provide, for example, a seal roll between the coating chambers.

  By using the PVD coating apparatus having the above-described configuration, a coating film having an arbitrary composition can be formed for each coating chamber of the PVD coating band 20. For example, a very high purity Ti metal (typically the first type titanium strip specified in JIS H 4600) is installed in the first coating chamber 21A, and a low-cost Ti metal ( (Typical type 2 titanium strip specified in JIS H 4600) is installed, and the third chamber 21C is installed with a strip made of Ti-Al alloy with low Al, and the fourth chamber 21D is Al. By arranging an Al-Ti alloy with a high content, a mixed layer, TiN layer, and surface layer can be sequentially formed on the surface of the unidirectional electrical steel sheet to be passed, and at that time, the TiN layer and surface layer Over this, the Al content can be increased as it reaches the surface of the coating.

  Contains C: 0.075 mass%, Si: 3.49 mass%, Mn: 0.073 mass%, Se: 0.020 mass%, Sb: 0.025 mass%, Al: 0.020 mass%, Mo: 0.011 mass% and N: 0.0070 mass% The remainder of the slab for magnetic steel sheet, which is substantially composed of Fe, is heated at 1350 ° C for 3 hours, then hot rolled to form a hot rolled sheet, and then cold-rolled twice with 1030 ° C intermediate annealing. To give a 0.23 mm cold-rolled sheet.

The obtained cold-rolled sheet was subjected to magnetic domain refinement treatment to form grooves with a width of 200 μm and a depth of 20 μm at intervals of 4 mm in a direction substantially perpendicular to the rolling direction, and also used for decarburization annealing in wet hydrogen at 840 ° C. After recrystallization annealing, an annealing separator composed of SiO ₂ : 3 mass%, Al ₂ O ₃ : ₂ mass%, MgO: 65 mass%, SbCl ₃ : 25 mass%, Sr (OH) ₂ : 5 mass% is applied. , After holding at 850 ° C for 15 hours, heating up to 1050 ° C at 13 ° C / h, and then performing final annealing to purify in dry hydrogen at 1220 ° C to expose the unidirectional electromagnetic radiation of the base metal without forsterite coating A steel plate was obtained.

  A PVD processing apparatus having the structure shown in FIG. 1 is used for the obtained unidirectional electrical steel sheet exposed to the ground iron, and the targets shown in Table 2 are installed in the multi-arc discharge sections 21A to 21D, respectively. PVD treatment was performed at 25V × 250A.

  In the comparative example, the process up to the final annealing was performed in the same manner as in the above example, and in the subsequent PVD process, the target was all the first type titanium.

After forming an insulating coating mainly composed of colloidal silica and phosphate on the obtained unidirectional electrical steel sheet with TiN coating, the strain relief annealing was performed in nitrogen at 800 ° C for 3h. . FIG. 6 shows a depth profile by GDS (Glow Discharge Spectroscopy) in the vicinity of the surface of the unidirectional electrical steel sheet before the formation of the insulating coating. Table 3 shows the mixed layer, TiN layer and surface layer thicknesses obtained from FIG. 6, the value of X in the general formula Ti _X N _(2-x) , and the content of Me (Al + Si) in the surface layer together with comparative examples. Show. Table 4 shows the characteristics of the product after strain relief annealing together with comparative examples.

  As can be seen from FIG. 6 and Table 3, in the present invention, the mixed layer, TiN layer, and surface layer are formed on the ground iron, and the content of Me (Si + Al) in the TiN layer and the surface layer is from the mixed layer side. It increases as it reaches the surface of the surface layer. Thereby, the adhesiveness and heat resistance of the TiN-based coating are ensured. Further, as can be seen from Table 4, when the TiN coating according to the present invention is deposited, the magnetic properties are excellent and the adhesion of the coating after strain relief annealing is excellent. The film adhesion is measured by the minimum diameter at which the film does not peel when bent by 180 °.

It is a schematic explanatory view showing the surface structure of the unidirectional electrical steel sheet according to the present invention. It is an example of the depth profile by the surface near-surface GDS of the unidirectional electrical steel sheet obtained when increasing Si from the mixed layer side to the outermost layer according to the present invention. This is an example of the GDS depth profile near the surface of the unidirectional electrical steel sheet obtained when Al is increased from the mixed layer side to the outermost layer according to the present invention. It is a schematic cross section which shows an example of the apparatus for implementing this invention. It is an expansion explanatory view of the multi-arc discharge part used for the device shown in FIG. It is a chart of the near surface GDS depth profile of the unidirectional electrical steel sheet of the Example according to this invention.

Explanation of symbols

10: Inlet differential pressure zone
11 (11A to 11D): Seal roll
12 (12A-12C): Exhaust port
13 (13A-13C): Entry side differential pressure chamber
20: PVD coated belt
21 (21A-21D): Coating room
22 (22A-22D): Exhaust port
24 (24A-24C): Partition wall
23 (23A-23D): Reaction gas inlet
25: Outer wall of coating room
26: Target
27: Bar magnet
28: Bar magnet
29: Power supply
30: Outlet differential pressure zone
31 (31A to 31D): Seal roll
32 (32A to 32C): Exhaust port
33 (33A to 33C): Outlet differential pressure chamber
34 (34A to 34D): Multi-arc discharge section
42: Steel (unidirectional electrical steel sheet)
43: Mixed layer
44: TiN layer
45: Surface
46: Surface part (of surface layer 45)
47: (Overcoat) Insulating coating

Claims (5)

It has a mixed layer containing Fe, Ti and N on the surface of the unidirectional electrical steel sheet that has been annealed,
The mixed layer has a TiN layer composed of the general formula Ti _X N _(2-X) (where X is 0.2 to 1.3) excluding inevitable impurities,
Further, Ti-Me-N (Me is Si and / or Al) excluding inevitable impurities on the TiN layer, and having a surface layer containing 5 to 70 mass% Me,
The unidirectional electrical steel sheet according to claim 1, wherein the MeN content of the TiN layer and the surface layer is increased from the mixed layer side to the surface portion of the surface layer.   The unidirectional electrical steel sheet according to claim 1, further comprising an insulating coating containing phosphate and silica on the surface layer. In the method for producing a unidirectional electrical steel sheet, in which a TiN-based coating is formed on the surface of the finish annealed unidirectional electrical steel sheet by the PVD method,
While forming a mixed layer containing Fe, Ti and N on the surface of the unidirectional electrical steel sheet, a TiN layer composed of a general formula Ti _X N _(2-X) (where X is 0.2 to 1.3) except for inevitable impurities After forming
It consists of Ti-Me-N (where Me is Si and / or Al), excluding inevitable impurities, and forms a surface layer containing 5 to 70 mass% of Me,
At that time, the content of Me in the TiN layer and the surface layer is increased as it reaches from the mixed layer side to the surface portion of the surface layer.   The method for producing a unidirectional electrical steel sheet according to claim 3, wherein an insulating film containing phosphate and silica is formed on the surface layer. In a PVD processing apparatus comprising an inlet side differential pressure chamber for sequentially passing a strip, a PVD coating zone, and an exit differential pressure chamber, and applying a coating on the surface of the strip,
The PVD coating strip is constituted by a plurality of coating chambers connected to each other and partitioned by a partition plate, and each of the plurality of coating chambers includes at least a pair of multi-arc discharge portions and a passage of the strip-shaped body. A PVD processing apparatus comprising: at least one reactive gas introduction hole; and a target having an arbitrary composition can be disposed in the multi-arc discharge section.

Images