JP2008106287A - Nitride-containing target material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a target material used in an AIP (arc ion plating) process and an MS (magnetron sputtering) process, in which mechanical strength is improved, and further, the formation of droplets is suppressed, and which is suitable for forming a film having high quality. <P>SOLUTION: In a target material comprising Al and an M component(s); wherein, the M component(s) is one or more kinds of elements selected from the group 4a, 5a and 6a metals, Si, B and S, the target material in this invention is a nitride-containing target material comprising Al and the M component(s) and the nitride of Al. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a nitride-containing target material for forming a film on the surface of a cutting tool or metal part, and in particular, arc ion plating (hereinafter referred to as AIP) method, magnetron sputtering (hereinafter referred to as MS). It is related to the target material as the evaporation source.

  In the coating using an alloy target material containing an Al component as an evaporation source, the occurrence of droplets due to the Al component is a problem, and a technique for reducing the occurrence of droplets is disclosed in Patent Document 1 below. 6.

JP 2004-99966 A Japanese Patent Laid-Open No. 10-60636 JP-A-8-120445 JP-A-8-134635 JP 2003-286666 A JP 2003-286564 A

  The problem to be solved by the present invention is a target material used in the AIP method and the MS method, in order to improve mechanical strength, suppress formation of droplets, and form a high-quality film. It is to provide a suitable target material.

The present invention relates to a target material having one or more elements selected from Al and M components, wherein the M component is selected from 4a, 5a, and 6a group metals, Si, B, and S. A nitride-containing target material comprising a component and Al nitride. By adopting the above configuration, when coated by the AIP method and MS method, the mechanical strength is improved, the generation of droplets is suppressed, and a suitable target material for forming a high quality film Can be provided.
In the nitride-containing target material of the present invention, the content of Al nitride is preferably 5% or more and 30% or less in terms of mol%. Further, in the nitride-containing target material, it is preferable that 0.3 ≦ Q ≦ 2 when the ratio of the content of Al nitride to Al (Al nitride) / (Al) is Q. .

  The present invention provides a target material used in the AIP method and the MS method, which is suitable for forming a high-quality film in which mechanical strength is improved and generation of droplets is suppressed. I was able to.

The nitride-containing target material of the present invention is used for obtaining a film such as a nitride having Al and M components. In the AIP method, a target material, which is a raw material of a film, is instantaneously dissolved and ionized by arc discharge in a reduced-pressure reaction gas atmosphere, and adhered to a negatively applied coating substrate to form a film. At this time, the dissolved target material is ionized together with the reaction gas in the plasma generated between the coated base material and the target material. For example, a TiAl-based or CrAl-based hard coating is used as a coating nitrided using nitrogen as a reaction gas. When a TiAl-based or CrAl-based target material is used and a hard film is coated by the AIP method, an arc spot at the time of arc discharge is formed as a site for emitting electrons on the target surface. One or a plurality of arc spots are present during the discharge at the same time, and it is necessary to move at high speed and uniformly on the target surface. However, when the movement of the arc spot is retained, a large dissolved portion is generated in the retained portion, and the dissolved droplet adheres to the substrate surface. The adhered dissolved droplets are called droplets or particles, macro particles, and the like, and cause the surface of the hard coating to be roughened. For example, when a large number of droplets adhere to the coated tool, the tool performance is deteriorated. When the target material is homogeneous, such as a single metal or a single structure, the arc spot tends to move uniformly on the surface of the target material. However, when the target material is inhomogeneous due to being composed of a plurality of elements or includes a plurality of phases, the arc spot is difficult to move uniformly, and droplets are likely to be included on the coating surface.
In particular, when a target used in the AIP method contains Al having a low melting point, Al surrounds the M component element which is another constituent element as a binder, and a compound is formed at the interface. This compound becomes an AlM-based intermetallic compound. When the M component element is composed of two or more elements, this compound forms an AlMy1My2 compound (where y1 ≠ y2). In the AIP method, when the target to be used contains low melting point Al, arc discharge tends to concentrate particularly on the Al single phase portion. As a result, a lot of droplets are contained on the hard coating surface, resulting in deterioration of surface roughness and non-uniform composition. The hard film containing huge droplets has a drawback that the droplet portion becomes a macro defect and the hardness, heat resistance and fracture resistance are lowered.

By using the nitride-containing target material of the present invention, the mechanical strength is improved, and a film with very little droplet generation can be obtained. This is because the inclusion of AlN can reduce the Al single phase that tends to be a droplet generation source without reducing the amount of Al component in the entire target. In addition, the presence of Al nitride in the very vicinity of the Al single phase on the evaporation surface improves the mechanical strength and the selective dissolution of Al due to the high affinity between Al and Al nitride. Can be avoided, the concentration of arc discharge can be avoided, and the amount of droplets can be reduced. This is because Al nitride is a higher melting point material than the Al single phase. As a result, the generation of huge droplets is suppressed. In addition, Al nitride has high thermal conductivity, and at the time of sintering, it has the effect of promoting diffusion between target constituent elements, so the mechanical strength is improved, and the Al single phase having a low melting point is reduced. This has the effect of preventing the concentration of arc spots.
Moreover, since the film | membrane which reduced the droplet does not divide the crystal growth, it forms a high-density film | membrane and is excellent in mechanical strength. In the target, a nitride-containing phase is preferably present around the Al nitride phase. Furthermore, the Al nitride contained in the target diffuses into the M component, thereby increasing the mechanical strength of the target itself.

The nitride-containing target material of the present invention contains Al nitride, and the content thereof is preferably 5% or more and 30% or less in mol%. When the content of Al nitride is less than 5%, the effect of increasing the moving speed of the arc spot cannot be obtained, so the amount of droplets cannot be reduced. Moreover, there is little effect which raises mechanical strength. On the other hand, when it exceeds 30%, a denitrification phenomenon is likely to occur during the production of the target, and voids are formed inside the target. A large amount of oxygen is taken into the vacancies and a large amount of oxygen, which is an impurity, is taken in, and the mechanical strength deteriorates. As a result, not only instability factors such as local discharge and discharge stop increase at the time of discharge, but also there is an inconvenience that cracking occurs due to an impact caused by arc discharge.
The nitride-containing target material of the present invention preferably has a Q value of 0.3 ≦ Q ≦ 2. By setting to the above range, it is possible to obtain the effect of increasing the moving speed of the arc spot while maintaining the mechanical strength of the target material. When the Q value exceeds 2 and the target tissue is dispersed in a poor state, a high-quality film cannot be obtained. If it is less than 0.3, it is difficult to obtain the effect of improving the mechanical strength of the target material.

  The Al nitride particles in the nitride-containing target material of the present invention preferably have an average particle size of 5 μm or more and 100 μm or less. When the average particle size is less than 5 μm, the amount of impurities contained in the particles increases. This degrades the mechanical strength of the target material and has the disadvantage that cracks occur due to impacts such as arc discharge. On the other hand, when the thickness exceeds 100 μm, the dispersed state of the target structure is deteriorated and a high-quality film cannot be obtained. The crystal orientation of the Al nitride particles is preferably basically (100) plane orientation, but particles having other orientations may be used.

  The oxygen content in the Al nitride-containing target material of the present invention is preferably 0.7% or less by mass%. If the content exceeds 0.7%, not only the mechanical strength of the target material is inferior, but also oxygen ions generated during discharge oxidize the target surface, thus forming an electrical insulating material. As a result, the discharge becomes unstable, and an abnormally dissolved portion of the target is easily formed.

In the case of manufacturing a target material containing Al such as TiAl-based or CrAl-based using a hot press method, Al, which is a metal having a lower melting point than Ti and Cr, serves as a binder for binding other metal elements. For example, in the case of a TiAl-based alloy, a structure of an Al single phase is generated in addition to an intermetallic compound such as a Ti phase, a TiAl phase, a Ti3Al phase, and an Al3Ti phase. In this Al single phase, the arc spot is stagnated, and a huge droplet exceeding 1 μm in length is generated. If this droplet is generated in a large amount, it will cause a decrease in the excellent function of the hard film to be formed, so it is necessary to reduce the Al single phase. Therefore, in the powder metallurgy method by the hot press method, it is preferable to fabricate at 600 ° C. or lower in which Al is not melted in an atmosphere containing Ar or N 2 under reduced pressure. When the temperature exceeds 600 ° C., the Al single phase increases, and Al does not function as a binder. In addition, denitrification of Al nitride occurs. In addition, when Al carbides or oxides are generated, there is a drawback that the electric resistance of the target is increased and discharge becomes difficult. The target material of the present invention can be produced not only by the hot press method by powder metallurgy but also by the HIP method. When the HIP method is applied, it is preferable to perform pressurization in the range of 100 MPa to 300 MPa in an atmosphere containing Ar or N2. Carbonitride may also be present together with Al nitride. That is, the Al nitride in the target may be Al carbonitride obtained by carbonizing Al nitride particles, or Al carbonitride obtained by nitriding Al carbide.
When the target of the present invention is used, the mechanical strength such as hardness, density, toughness, etc. of the resulting hard coating is increased, so it is effective to use it for coatings that require fracture resistance and wear resistance. is there. If it is used to form a thick film exceeding 6 μm, it is possible to form a high-density hard film with few droplets. Furthermore, it is suitable for an application such as a drill, an end mill, or a micropart where adhesion of droplets is not preferred at a portion to be used. Hereinafter, the present invention will be described based on examples.

(Example 1)
A target material for AIP was produced by powder metallurgy. In production, when producing a hard film, in order to obtain a hard film having excellent wear resistance and heat resistance, one or more selected from Al and 4a, 5a, 6a group metals, Si, B, S The raw material powder and Al nitride were mixed in an Ar atmosphere for 4 hours using a ball mill as a sealed container. In the case of containing S, it was difficult to handle the powder of S alone, so sulfide was used. In consideration of powder mixing properties, 99.999% or more of Al2O3 balls were used in order to avoid compositional deviation and mechanical strength reduction. A predetermined amount of the mixed powder was charged into a graphite mold and sintered using a hot press machine. In order to avoid dissolution of Al during sintering, the sintering temperature was set to 450 to 550 ° C. In sintering under reduced pressure, sintering was performed in an Ar or N atmosphere in order to avoid the influence of oxygen uptake into the target due to a trace amount of oxygen remaining in the sintering apparatus. The press load was set in the range of 50 MPa to 200 MPa. The sintering time was 1 to 3 hours. The target material completed after sintering was processed into a shape suitable for a bending strength test piece and an AIP apparatus.

  The presence state of the nitride-containing phase and the Al nitride in the structure was observed at a magnification of 2000 times using an electrolytic radiation scanning electron microscope (S-4200, manufactured by Hitachi, Ltd., hereinafter referred to as SEM). The component analysis of each phase was performed with the EDX analyzer equipped with SEM. Thereafter, the surface of the target material was treated with a hydrofluoric acid-based corrosive solution, and the same field of view was observed under the same conditions. In order to confirm the Al nitride and the Al phase, the structure of the prepared target was observed with a transmission electron microscope (hereinafter referred to as TEM). In order to examine the strength of the target material, the bending strength test piece was measured by three-point bending. Further, X-ray diffraction of Al nitride was performed under the conditions of Cu-kα, 2θ-θ method, tube voltage 50 kV, and tube current 160 mA.

The target material was attached to the AIP apparatus, and the insert for milling was coated. The coating treatment temperature was 600 ° C., the reaction pressure was 5 Pa, the bias voltage was 50 V, and the arc current value was 150 A. The substrate surface was coated with a film thickness of 3 μm. The amount of droplets adhering to the hard film was measured using SEM at a magnification of 3000 times. The total amount contained in a 1 mm square was measured using a droplet having a particle size of 0.5 μm or more as a measurement target.
Table 1 shows the target compositions and bending strengths of Invention Examples 1 to 10, Comparative Examples 11 and 12, and Conventional Examples 13 to 15, and the amount of microparticles and cutting life of the obtained films.

As a result of observing the structure on the surface of the target material of the example of the present invention by SEM, it was confirmed that a nitride-containing phase in which the nitride of Al diffused into the M component was present. The structure of Example 4 of the present invention was observed by TEM and the boundary between Al nitride and Ti as the M component was confirmed. As a result, a phase in which Al nitride was diffused was formed inside the Ti particles. confirmed.
Invention Examples 1 to 15 containing Al nitride had higher bending strength than Conventional Examples 16 to 19, and had a bending strength of 480 MPa or more. Inventive Example 4, which showed the highest bending strength among Inventive Examples, was 1.5 times the value of Conventional Example 16. Invention Example 9 also had a value 1.4 times or more that of Conventional Example 17. This is presumably because Al nitride contained in the target is diffused in a portion adjacent to the M component, and the bonding strength of the elements constituting the target is increased. Of the targets of Examples 1 to 15 of the present invention, those having an Al nitride content in the range of 5.0% or more and 30.0% or less exhibited high bending strength.

  The target material of the present invention example and the conventional example were installed in an AIP apparatus, and all were formed using the same film formation conditions. From Table 1, the number of droplets adhering to the surface of the hard coating obtained by containing the Al nitride of the present invention in the target is less than the number of droplets of the hard coating obtained from the target of the conventional example. It was. In the hard film obtained from the target containing AlN of Invention Examples 1 to 15, the number of droplets decreased as the AlN content increased. In the case where AlN was added to the TiAl targets of Invention Examples 1 to 4, the smallest amount of droplets was 8 k / mm2. The hard film obtained from the TiAl target of Conventional Example 16 was 25k pieces / mm2, and the amount of droplets was reduced by 70% or more. This tendency is the same when AlN is contained in the CrAl targets of Invention Examples 6 to 10 and when AlN is contained in the Al, Cr, Si, B, and S-based targets of Invention Examples 11 to 15. It was.

(Example 2)
The insert for milling coated with the target material prepared in Example 1 was subjected to cutting evaluation under the following conditions to confirm the superiority or inferiority of the wear resistance of the hard coating. The evaluation method is to observe the presence or absence of peeling or breakage of the hard coating that occurs when the cutting length is 1 m by magnifying the cutting blade flank face 50 times using an optical microscope, measuring the wear width, and further cutting. Continuing, the point in time when a defect including a fine chip of 10 μm or more occurred was regarded as the tool life, and the performance was evaluated by comparing the cutting distance (m) up to that point.
(Cutting specifications)
Tool: Special face milling insert shape: SDE53 type special shape Cutting method: Center cut method Workpiece shape: width 125mm x length 300mm
Work Material: Press Die Steel SKD11, HRC29
Axial depth of cut: 1.0 mm
Cutting speed: 130 m / min
Feed per blade: 0.5 mm / blade Cutting oil: none As shown in Table 1, the Al content in the target affected the number of droplets on the coating surface and the tool life. The tool life of Inventive Examples 1 to 5 was 17 m, 19 m, 25 m, 35 m, and 22 m, respectively, and 16 m in Conventional Example 16. Although the elements constituting the hard coating are the same, the tool life has changed greatly due to the difference in the form of the target used for coating the hard coating. In particular, when the Al nitride content was in the range of 5% to 30%, the cutting life was long. The invention example 4 having the best tool life was twice as good as the tool life of the conventional example 16. As a result of confirming the damage state of the cutting edge at the cutting distance of 1 m, the flank maximum wear widths of Examples 1 to 5 of the present invention were 0.078 m, 0.074 mm, 0.061 mm, 0.056 mm, and 0.070, respectively. On the other hand, the conventional example 16 was 0.130 mm. Peeling was not observed in any of the samples, and normal wear occurred. Finally, the sample was lost when the maximum flank wear width exceeded 0.500 mm. These tendencies are the same when AlN is contained in the CrAl targets of Invention Examples 6 to 10 and when AlN is contained in the Al, Cr, Si, B, and S-based targets of Invention Examples 11 to 15. Met. The above results are considered to be because the mechanical strength such as hardness, density, toughness and the like of the obtained hard coating was increased by reducing the number of droplets, and as a result, excellent tool life was exhibited.

Claims (3)

Al and M components, where the M component is a target material having one or more elements selected from Group 4a, 5a, and 6a metals, Si, B, and S. The target material is composed of Al, M component, and Al. A nitride-containing target material comprising a nitride. 2. The nitride-containing target material according to claim 1, wherein a content of the Al nitride is 5% or more and 30% or less in mol%. 3. The nitride-containing target material according to claim 1, wherein the ratio of the Al nitride content to the Al content (Al nitride) / (Al) is 0.3 ≦ Q. Nitride-containing target material, wherein ≦ 2.