JP4846563B2 - Nitride-containing target material - Google Patents

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. In particular, the present invention relates to a target material as an evaporation source for arc ion plating (hereinafter referred to as AIP) method and magnetron sputtering (hereinafter referred to as MS).

  Techniques relating to alloy target materials containing a B component in the evaporation source are disclosed in Patent Documents 1 and 2.

JP 2005-533182 A JP 2006-315173 A

The problem to be solved by the present invention is to provide a target material used for the AIP method, which is suitable for forming a high-quality film in which formation of droplets is suppressed.

The present invention relates to a target material for arc ion plating having an element B and an M component, wherein the M component has one or more elements selected from the periodic table 4a, 5a and 6a group metal elements, Si and S. The target material contains 5% or more and 30% or less of M component nitride or carbonitride, and the nitride or carbonitride has a structure adjacent to the compound containing B element. This is a nitride-containing target material. By employing the above configuration, when coating is performed by the AIP method or the MS method, the generation of droplets is suppressed, and a suitable target material for forming a high-quality film can be provided.
Further, the nitride or carbonitride of the M component in the nitride-containing target material of the present invention has a face-centered cubic structure, and the peak intensity of the (111) plane in X-ray diffraction is IA, When the peak intensity is IB, the peak intensity ratio IB / IA is preferably 1 ≦ IB / IA ≦ 10.

By this invention, it was a target material used by AIP method, Comprising: The target material suitable for forming the high quality film | membrane in which the production | generation of the droplet was suppressed was able to be provided.

The nitride-containing target material of the present invention has a B element and an M component, where the M component is a nitridation composed of one or more elements selected from Periodic Tables 4a, 5a and 6a group metal elements, Si and S It is used to obtain a film such as a product or carbonitride. When a hard film is coated by the AIP method using a target material containing B element, an arc spot that emits electrons is formed on the target surface during arc discharge. Ideally, this arc spot has one point or a plurality of points at the same time during the discharge and moves on the target surface at high speed and uniformly. When the movement of the arc spot is retained, a large dissolved portion is generated in the retained portion, and the dissolved portion adheres to the substrate surface. The adhering dissolved droplets are called droplets, particles, or macro particles, which cause the surface of the hard coating to be roughened and deteriorate the coating performance.
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, so that problems are less likely to occur. On the other hand, when it is composed of a plurality of elements or includes a plurality of phases, the target material becomes inhomogeneous, the arc spot is difficult to move uniformly at high speed, and droplets etc. are easily included on the hard coating surface. There is a problem. For example, when a target material containing a B element such as a Ti-B system or a Cr-B system having a high heat resistance property is manufactured by using a hot press method, a compound is formed by reacting Ti, Cr and B. . Therefore, when the target material is, for example, a Ti—B alloy, a structure of a compound such as a TiB phase or a TiB2 phase is formed in addition to the Ti single phase and the B single phase. However, an arc spot stays in this compound phase, and a huge droplet having a diameter exceeding 1 μm is likely to be generated on the surface of the film. 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. Since a hard film with few droplets does not disrupt crystal growth, it forms a high-density film and has excellent mechanical strength. Further, the compound part composed of the M component and B element such as TiB2 is subject to cracking in the target material due to thermal shock that increases due to the stay of the arc spot, and abnormal discharge or the like is likely to occur. For example, when coating a tool or the like, not only a film forming apparatus but also a hard film covering member is adversely affected.

By using the nitride-containing target material of the present invention, it is possible to realize a target material that generates very little droplets without deteriorating the mechanical strength of the target material. The first reason is that the inclusion of an M component nitride and carbonitride in the target material containing the B element suppresses the formation of a compound of the M component and the B element (hereinafter referred to as MxBy). Because it can. The second reason is that the presence of the M component nitride and carbonitride significantly increases the motion speed of the arc spot.
Therefore, the first reason will be described. The element B has a characteristic of reacting with a component component M phase as a constituent element in an attempt to form a stable compound at a high temperature. However, when the component M is contained in the form of nitride or carbonitride, Since the abundance ratio of the M component single phase in the target can be reduced, this reaction is suppressed. As a result, the opportunity for formation of MxBy compounds is reduced. If the MxBy compound decreases, the concentration of arc discharge also decreases, and the amount of droplets adhering to the hard coating can be reduced. Decreasing the MxBy compound can simultaneously avoid a decrease in bonding strength at the grain boundaries of the structure, so that a target material having excellent mechanical strength can be realized.
Next, the second reason will be described. For the above reasons, even if the formation of the MxBy compound can be suppressed to some extent, the presence of the MxBy compound cannot be eliminated. Therefore, the amount of droplets can be reduced by forming a structure in which the nitride of the M component and the carbonitride specified by the present invention are adjacent to a compound containing B element, for example, an MxBy compound. This is because the nitrogen and carbon dissolved and evaporated from the M component nitride and carbonitride during the target discharge are ionized in the vicinity of the target surface, so that the movement speed of the arc spot is remarkably increased, and at the same time, the arc of the MxBy compound This is because concentration of discharge can be avoided.
Here, the structure in which the nitride of the M component and the carbonitride are adjacent to the compound containing the B element means that the MxBy compound formed by the reaction between the M component single phase and the B component single phase is the M component single phase. It exists in the region of the contact interface with the B component single phase, and the M component nitride and carbonitride exist so as to fill the gaps between the respective phases, so that the MxBy compound and the M component nitride, carbon Nitride forms an adjacent structure. At this time, the M component nitride and carbonitride particles preferably have an average particle diameter of 5 μm or more and 100 μm or less. Since the target of the present invention does not actively form a solid solution phase with the elements constituting the target, the amount of the solid solution phase is small.
Further, when the M component is composed of two or more elements, an Mx1Mx2By-based compound, where x1 ≠ x2, is formed. For example, in the AIP method, arc discharge tends to concentrate on the boundary portion between the B component single phase and the Mx1Mx2By compound. As a result, a lot of droplets are contained on the surface of the hard coating, resulting in deterioration of surface roughness and non-uniform composition. This becomes a factor of deteriorating the wear resistance and fracture resistance of the hard film-coated member. Therefore, the target material of the present invention needs to contain M component nitride and carbonitride.
The target material of the present invention can suppress the formation of the MxBy compound by adjusting the content of the M component nitride and carbonitride to 5% or more and 30% or less in terms of mol%. When the formation of the MxBy compound is suppressed, the bonding strength between the elements and compounds constituting the target material is increased, and a target material having high mechanical strength can be realized. When the content of the M component nitride and carbonitride is less than 5%, the effect of suppressing the formation of the MxBy compound of the target material cannot be obtained. As a result, the bonding strength at the texture grain boundary decreases, and the mechanical strength of the target material decreases. On the other hand, if it exceeds 30%, the sinterability of the target material is lowered, and a high-density target material cannot be realized. The density of the target material must exceed 95%, but the density at this time may be less than 80%, which reduces the mechanical strength of the target material. Further, when the target material is sintered, the denitrification phenomenon of M component nitride and carbonitride tends to occur, and voids are formed inside the target material. Therefore, the inconvenience that nitride and carbonitride cannot be controlled in the structure adjacent to the MxBy compound occurs. The formed vacancies contain a large amount of oxygen, and there are unstable elements of discharge such as local discharge and discharge stop, and there are inconveniences that cracking occurs due to impact caused by arc discharge. Furthermore, when the denitrification phenomenon occurs, the reaction between the M component and the B element occurs vigorously, and the formation of the MxBy compound or the intermetallic compound of the M component and the B element is promoted. At that time, since a very high exothermic reaction is accompanied, cracks are likely to occur, and there is a drawback that the mechanical strength of the target material deteriorates. In particular, in the case of a target material containing Ti and B, it is extremely dangerous because Ti and B are accompanied by a vigorous exothermic reaction when forming an intermetallic compound.

  The nitride and carbonitride of the M component contained in the target material of the present invention have a face-centered cubic structure, and the peak intensity ratio IB / IA value in X-ray diffraction of this nitride and carbonitride is 1 ≦ It is preferable that IB / IA ≦ 10. When a nitride having a crystal structure other than the face-centered cubic structure is included, it is difficult to obtain a target having a high density. As a result, a large number of holes are generated, resulting in a drawback that the mechanical strength of the target material is lowered. When IB / IA <1, it is strongly oriented in the (111) plane, the density of atoms filled in the crystal lattice is increased, and the hardness is increased, but there is a disadvantage that the mechanical strength of the target material is deteriorated. appear. Further, the B element reacts with the nitride and carbonitride of the M component. As a result, a nitride or carbonitride containing B element and M component is formed, and there are defects such as a decrease in mechanical strength of the target material and a deterioration in workability of the target material. On the other hand, in the case of IB / IA> 10, there is a disadvantage that many nitrides and carbonitrides of the M component cause a denitrification phenomenon when the target material is sintered, and a lot of voids are formed in the target material. . As a result, the mechanical strength of the target material deteriorates, and there is a drawback that cracks are likely to occur. For example, the bending strength may be reduced by 40%. In addition, since the denitrification phenomenon occurs, the movement of the arc spot moving on the surface of the target material becomes slow, and huge droplets are included in the hard coating. In a hard film containing huge droplets, the droplet portion becomes a macro defect, and there is a defect that hardness, heat resistance, and fracture resistance are lowered. The peak intensity ratio IB / IA value in the X-ray diffraction can be controlled by the production conditions for producing the M component nitride and carbonitride. Further, the nitride or carbonitride of the M component preferably has conductivity. Therefore, when BN is contained, the conductivity of the target material is lowered, and a disadvantage that arc discharge is stopped appears.

When there are two or more types of M component to be contained in the target material of the present invention, the effect appears even if one of them is contained as a nitride or carbonitride. M component nitride and carbonitride particles preferably have an average particle size of 5 μm or more and 100 μm or less. When the particle size of the particles is less than 5 μm, the amount of impurities contained in the particles increases and is contained as it is in the target material. As a result, the mechanical strength of the target material deteriorates, and a defect that cracks occur due to an impact such as arc discharge appears. Moreover, when the particle diameter exceeding 100 μm is contained, arc discharge generated on the surface of the target material is concentrated on the particles, and there is a disadvantage that the droplets are increased. The existence form of the nitride and carbonitride of the M component can be confirmed with a transmission electron microscope (hereinafter referred to as TEM) or a metal microscope.
The target material of the present invention is preferably a target material having excellent mechanical strength by reducing the area ratio of the MxBy compound on the target surface. If the M component nitride or carbonitride exceeds 30%, the MxBy compound area ratio may exceed 50%. As a result, there are disadvantages in that the mechanical strength is reduced, and there is a disadvantage in that the arc discharge is stopped due to the decrease in conductivity. Therefore, the formation of the MxBy compound is preferably 50% or less in terms of area ratio. When 1 ≦ B / A ≦ 10, the area ratio of the MxBy compound to be formed is 50% or less, the amount of droplets is reduced, and a hard film having excellent mechanical strength can be obtained. On the other hand, it is difficult to make the area ratio of the MxBy compound less than 10%.

The oxygen content in the target material of the present invention is preferably 0.7% or less by mass%. If it contains more than 0.7%, not only the mechanical strength of the target material is remarkably inferior, but also the oxygen ions generated during discharge oxidize the surface of the target material and oxidize the contained B at an early stage. Forming an electrically insulating state. As a result, the discharge becomes unstable, and an abnormally dissolved portion of the target material is easily formed. In the case of a compound containing an M component carbide or oxide, it is not preferable because the electric resistance of the target material becomes high and discharge becomes difficult.
The target material of the present invention is made into an atmosphere containing Ar or N2 under reduced pressure by a powder metallurgy method such as a hot press method, and the temperature rises slowly in the range of 1000 ° C. to 1400 ° C., preferably in the range of 1050 to 1300 ° C. This can be realized by making them. When the processing temperature exceeds 1400 ° C., the B element reacts violently with the M component, making it impossible to produce the target material, and the denitrification phenomenon of the M component nitride and carbonitride occurs. , Nitride and carbonitride are difficult to exist. Further, the M component nitrides and carbonitrides do not exist so as to be adjacent to the MxBy compound, resulting in a drawback that the mechanical strength of the target material is lowered. For example, a form in which the MxBy compound segregates is not preferable. In the target material of the present invention, it is necessary to control the sintering conditions so that the nitride and carbonitride of the M component have a structure adjacent to the MxBy compound. For this purpose, it is preferable that the temperature is increased slowly from about 800 ° C. at a temperature increase rate of about 150 ° C./hour. The target material of the present invention can be produced by a powder metallurgy method and can be produced not only by a hot press method but also by an HIP method. When applying the HIP method, it is possible to perform pressurization in the range of 100 MPa to 300 MPa in an atmosphere containing Ar or N2. In the case of a compound containing an M component carbide or oxide, the electric resistance of the target material becomes high, and it is difficult to discharge, and therefore, it is not preferable.
For the technique of coating the target material of the present invention with a TiB-based, CrB-based nitride film or carbonitride film for the purpose of improving high wear resistance, heat resistance characteristics, and high lubrication characteristics, for example, on the surface of a tool, etc. In the case of application, it is preferable to use a target material containing a TiB-based or CrB-based B element as the evaporation source of the hard film coating, and perform film formation by the AIP method or the MS method. In order to obtain a TiB-based nitride hard film, a TiB-based target material is suitable.
When the target material of the present invention is used, the mechanical strength such as hardness, density, toughness, etc. of the hard coating is increased, so that it is effective to use it for applications requiring fracture resistance and wear resistance. . That is, if it is used when forming a thick film exceeding 6 μm, it is possible to form a high-density hard film with few droplets. Moreover, it is suitable for applications where adhesion of droplets is not preferred, such as drills, end mills, and micro parts. Hereinafter, the present invention will be described in more detail based on examples.

Example 1
A target material to be attached to the AIP apparatus was produced by a powder metallurgy method. In production, in order to obtain a hard film having excellent wear resistance, heat resistance characteristics and lubrication characteristics when a hard film is produced, a raw material powder of B element and M component, a nitride of face-centered cubic structure of M component, Carbonitride raw material powder was mixed for 4 hours in an Ar atmosphere in a closed container such as a ball mill. When the S component is contained, it is difficult to handle the powder of S alone, so mixing was performed as a sulfide. When mixing with powder alone, the mixing property is poor, and there is a concern that the composition will be biased when the target material is used, and the mechanical strength may be lowered. Therefore, Al2O3 balls with a purity of 99.999% or more were used in the container. . A predetermined amount of the mixed powder was charged into a graphite mold and sintered using a hot press machine. If the B component is dissolved during sintering, various adverse effects are exerted on the apparatus, so the sintering temperature was set at 1000 to 1500 ° C. In addition, although sintering was performed under reduced pressure, sintering was performed in an Ar or N2 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 appropriately changed in a range of 50 MPa to 200 MPa so as to obtain a target material having predetermined characteristics. The sintering time was 1 to 3 hours. The target material after sintering was ground and turned so as to be attached to the AIP apparatus.

  In the obtained target material, the target structure was observed by using a hydrofluoric acid-based corrosive solution, and the existence form of nitrides and carbonitrides of M component was confirmed. M component nitrides and carbonitrides were subjected to X-ray diffraction, and the peak intensities appearing at the (111) plane and (200) plane positions of the face-centered cubic structure identified from the JCPDS file were compared. The X-ray diffraction conditions were Cu-kα, 2θ-θ method, tube voltage 50 kV, and tube current 160 mA. Further, in order to confirm the structure of the M component nitride, carbonitride and MxBy compound, the structure was observed with TEM. In order to examine the strength of the target material, after processing into a predetermined test piece shape, a bending test by three-point bending was performed.

  The target material obtained in Example 1 was attached to an AIP apparatus, and film formation was performed. For the base, parts that require wear resistance were selected, including insert tools shaped for milling and turning. The coating treatment temperature was 500 ° C., the reaction pressure was 3.5 Pa, the bias voltage was −50 V, the arc current value was 100 A, and the substrate surface was coated with a film thickness of 3 μm. In order to compare the amount of droplets adhering to the hard coating, the surface of the tool was observed using an electrolytic radiation scanning electron microscope (S-4200, manufactured by Hitachi, Ltd., hereinafter referred to as FE-SEM). Among the droplets included in a visual field of 3 k times and 10 μm in length and width, those having a particle size of 0.5 μm or more were measured. The evaluation results are shown in Table 1.

Invention Examples 1 to 4 and Comparative Examples 20 and 21 in Table 1 were prepared in order to observe the influence of the amount of nitride contained in the target material. Inventive Examples 5 to 7 and Comparative Example 22 were prepared in order to observe the influence of the nitride amount and the composition is different from Inventive Examples 1 to 4. Moreover, in order to see the influence of the target material from which a composition differs, this invention example 8-15 was produced. Invention Example 16 was prepared in order to observe the influence when carbonitride was contained. Invention Examples 17 and 18 were prepared in order to confirm the influence of the peak intensity ratio in the X-ray diffraction of the nitride content. Invention Example 19 and Comparative Example 23 were prepared as nitrides in order to observe the influence of the crystal structure. In Comparative Example 23, h-BN was contained. This is in order to compare with the case where it is made to contain especially by c-BN of the example 12 of this invention. The comparative example 24 was produced in order to confirm the influence at the time of containing a carbide | carbonized_material.
As shown in Table 1, the target material of the present invention had excellent bending strength and was excellent. Inventive Examples 1 and 2, which showed the highest bending strength among Inventive Examples, were 1.5 times better than Conventional Example 25. Invention Example 4 having the same composition system was also superior to 1.3 times or more. Invention Examples 5 to 7 having different composition systems were superior in bending strength to Conventional Example 26. Similarly, Invention Examples 8 to 15 containing nitrides having different compositions were superior to Conventional Examples 27 to 32. It is possible to suppress the formation of the compound by the M component and the B element by including an appropriate amount of the nitride and carbonitride of the M component in the target material containing the B element, and as a result, the MxBy compound is reduced. This is because a target material having excellent mechanical strength could be realized because a decrease in bonding strength at the grain boundaries of the structure was avoided. In Comparative Examples 20 and 22 in which the content of nitride and carbonitride in the target material was less than 5%, the mechanical strength and bending strength of the target material were low. In Comparative Example 21 in which the content of nitride exceeds 30%, the bending strength of the target material was remarkably lowered and inferior. Therefore, when the content of nitride or carbonitride is 5% or more and 30% or less, the bending strength is increased, which is an excellent result.

The surfaces of the target materials obtained in Invention Examples 1 to 4 and Comparative Examples 20 and 21 were mirror-polished, then corroded with a hydrofluoric acid-based corrosive solution, and the structure was confirmed at 1 k using an optical microscope. As a result, a TiN phase was confirmed. The structure of the TiN particles of Invention Example 2 was observed using a TEM (manufactured by Hitachi, accelerating voltage 20 kV), and the boundary between the TiN particles and the B single phase was observed in detail. It was confirmed that the components diffused and formed and formed phases.
The obtained target material was placed in an AIP apparatus, and film formation was performed using the same film formation conditions. From Table 1, the hard film obtained by using the target material of the present invention was superior in that the number of droplets adhering to the surface was smaller than that in the case of using the conventional target material. The number of hard coatings obtained from Invention Examples 1 to 4 was 40 in the largest case and 8 in the smallest, whereas the number of droplets of the hard coating obtained from Conventional Example 25 was 128. there were. Therefore, a reduction effect of 60% or more could be obtained. This tendency was similarly excellent when not only the target material containing TiN but also other nitrides or carbonitrides were contained. Moreover, the number of droplets was dependent on the content of nitride and carbonitride. As in Invention Examples 1 to 4, when the M component nitride or carbonitride contained 5% or more and 30% or less, it was small and excellent. Moreover, in the range up to 30%, the number of droplets decreased as the content increased. On the other hand, the comparative example 20 of the hard film | membrane obtained from the target material containing 4% of TiN was 117 pieces. Moreover, the comparative example 22 containing 4% of CrN was 132 pieces. Furthermore, the surfaces of the hard coatings obtained in Invention Examples 5 to 7 and Comparative Example 22 having different target material compositions had the same tendency. In Comparative Example 21 in which the content of nitrides and carbonitrides exceeds 30%, not only the bending strength of the target material is remarkably lowered but also the discharge cannot be performed. Therefore, it was confirmed that those exceeding 30% cannot be used practically. The target materials of Invention Examples 8 to 15 containing not only the Ti-B system and Cr-B system but also the periodic table 4a, 5a, 6a group elements, Si, and S were excellent in the number of droplets. . In the case of Inventive Example 19 and Comparative Example 23 containing hexagonal nitride, Inventive Example 19 of Si nitride has 88 droplets, which is relatively smaller than Conventional Example 25, while h-BN. The comparative example 23 was 298, which was larger than the conventional example 30, but the cause is unknown. In the case of Comparative Example 24 containing TiC, discharge could not be performed and film formation could not be performed.
When the peak intensity of the (111) plane in the X-ray diffraction of a face-centered cubic structure nitride or carbonitride contained in the target material is IA and the peak intensity of the (200) plane is IB, the peak intensity ratio IB / IA was investigated. Inventive Example 2 had 23 droplets, whereas Inventive Example 17 with IB / IA <1 had 70, and Inventive Example 18 with IB / IA> 10 had 75. From the above, it was confirmed that by setting 1 ≦ IB / IA ≦ 10, the amount of droplets was reduced and excellent.

(Example 2)
About the insert for milling produced in Example 1, the cutting test was done on the following conditions, and the superiority or inferiority of the abrasion resistance of a hard film was confirmed. In the evaluation method, the presence or absence of peeling or breakage of the hard coating that occurred when the cutting length was 1 m was observed using an optical microscope with the cutting blade flank portion magnified 50 times. Then, the cutting was continued, and the performance was evaluated by comparing the cutting distance (m) up to that point when the chip life including a chipping of 10 μm or more was found.
(Cutting test conditions)
Tool: Special face milling insert shape: SDE53 type special shape Cutting method: Center cut work material shape: width 125mm x length 300mm
Work material: SKD11, steel for press dies, hardness, HRC29
Axial depth of cut: 1.0 mm
Cutting speed: 130 m / min
Feed per blade: 1.3 mm / blade cutting oil: None

As shown in Table 1, the number of droplets was found to affect the tool life in cutting. That is, the cutting performance of the hard coating obtained by containing nitride and carbonitride in the target material was excellent. For example, the tool life of Inventive Examples 1 to 4 was 29.7 m, 32.4 m, 34.0 m, and 34.1 m, respectively, while the tool life of Conventional Example 25 was 14.0 m. Even if the elements constituting the obtained hard coating were the same, the tool life was greatly affected by the difference in the form of the target material. When the inventive examples 1 to 4 and the comparative example 20 were compared, the TiN amount was 5% or more, and the tool life was excellent as the content increased. Invention Example 4 with the best tool life was 2.4 times the tool life of Conventional Example 25. On the other hand, when the TiN content was less than 5%, the tool life was almost the same as the conventional example.
As a result of confirming the damage state of the blade edge at the cutting distance of 1 m, the flank maximum wear width VBmax of the example of the present invention was 0.054 mm, whereas the conventional example 25 was as large as 0.098 mm. In both cases, no peeling was observed, and normal wear was observed, and finally, the chip was lost when the maximum flank wear width exceeded 0.300 mm. This result is because the mechanical strength such as hardness, density, and toughness of the obtained hard coating is increased by reducing the number of droplets, and as a result, excellent tool life is shown.

Claims (2)

B element and M component, wherein the M component is a target material for arc ion plating having one or more elements selected from Periodic Tables 4a, 5a and 6a group metal elements, Si and S. Comprises 5% or more and 30% or less of M component nitride or carbonitride, and the nitride or carbonitride has a structure adjacent to a compound containing B element. Nitride-containing target material.   The nitride-containing target material according to claim 1, wherein the M component nitride or carbonitride has a face-centered cubic structure, and the peak intensity of the (111) plane in X-ray diffraction is IA, A nitride-containing target material, wherein the peak intensity ratio IB / IA is 1 ≦ IB / IA ≦ 10 when the peak intensity is IB.