JP2008264989A - Cutting tools - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cutting tool having both wear resistance and fracture resistance.
A cutting tool comprising a base material (10) having a hard phase (11) and a binder phase (12) for binding the hard phase, and a coating layer (20) formed on the surface of the base material (10), the coating layer (20). Includes a vertical growth portion 21 that has grown at an angle of 85 to 90 degrees with respect to a plane orthogonal to the thickness direction, and a multi-direction growth portion 22 that has grown at an angle of less than 85 degrees with respect to the plane. (I) in a cross section cut in the thickness direction, the multidirectional growth portion occupies 5 to 40% of the length range of a straight line of 20 μm at the interface between the base material and the coating layer, and (ii) the thickness direction The width of the multi-directional growth part increases from the outer surface of the coating layer toward the base material side, and (iii) the cross-section cut in the thickness direction between the base material and the coating layer. Within a straight line of 20 μm on the interface, independent of each other The overgrowth portion is present 3-40 amino satisfies at least one of.
[Selection] Figure 1

Description

  The present invention relates to a cutting tool useful as, for example, a solid type drill, end mill, turning, milling, throw-away tip for drilling, and the like. Specifically, the surface of a base material made of a hard alloy is covered with a coating layer. It is related with the cutting tool coat | covered with.

  For example, hard materials such as cemented carbide, cermet, etc., composed of a hard phase mainly composed of titanium carbonitride (TiCN) or tungsten carbide (WC) and a binding phase of an iron group metal such as cobalt (Co) or nickel (Ni). Hard alloys in which solid solutions such as carbides, nitrides, carbonitrides of Group 4, 5, and 6 metals in the periodic table are dispersed in cemented carbides or WC-Co based cemented carbides have been conventionally used as cutting tools. It is known as a suitable material. For the purpose of further reinforcing the hardness, a cutting tool is widely used in which a coating layer made of a hard film having a hardness higher than that of the hard alloy is formed on the surface of the base material made of the hard alloy.

  However, when forming a coating layer on the surface of a base material that is a hard alloy, if a coating layer is formed directly on the burned skin surface of the fired hard alloy, a decarburized layer inevitably generated by sintering on the surface of the hard alloy or Due to the presence of a heterogeneous layer such as a metal-enriched layer and a large surface roughness, the adhesion of the coating layer to the base material is reduced, and there is a problem that film peeling occurs during cutting. . Also, when the base material is ground by machining to produce a shape according to the application, processing alteration that occurs on the surface of the base material due to adhesion of grinding scraps, generation of cracks, interface defects between the hard phase and the binder phase, etc. The layer also causes a decrease in adhesion with the coating layer. When peeling between the base material and the coating layer occurs, the wear resistance is lowered and the life as a cutting tool is shortened.

Therefore, in forming a coating layer on the surface of the hard alloy, a method has been proposed in which the surface of the hard alloy base material is preliminarily processed to improve the adhesion of the coating layer to the hard alloy base material. For example, by setting the average surface roughness Ra of the surface including at least the cutting edge of the hard alloy base material to a specific range by brush polishing, a cemented carbide with improved adhesion of the hard film (Patent Document 1), a specific It is a sintered alloy (Patent Document 2) in which cracks due to machining are not present in the hard phase on the surface of the hard alloy base material by electrolytic polishing in an electrolytic solution.
JP-A-6-108253 Japanese Patent Application Laid-Open No. 2000-212743

  However, according to the hard alloys described in Patent Document 1 and Patent Document 2, the adhesion of the coating layer is improved and an improvement in wear resistance can be expected, but the toughness is insufficient and the fracture resistance is satisfactory. It was not at a possible level. The cause is that the entire surface of the base material is uneven when brush polishing or electrolytic polishing is performed so that the desired average surface roughness Ra is obtained or cracks are not present in the hard phase of the base material surface. Therefore, when a hard film is formed as a coating layer thereon, it is considered that crystal grains (columnar crystals) are aligned in the same direction as the film growth direction. In other words, if the crystal grows in various directions, shrinkage that occurs during cooling after coating occurs in various directions, and thermal stress is dispersed to achieve high toughness. However, when the crystal arrangement is aligned, the film can contract only in the same direction, and the thermal stress generated in the cooling process is not dispersed or relaxed, and the toughness is lowered. In addition, when the crystal arrangement is aligned, crystal growth is not disturbed in the process, and generation of microvoids can be suppressed, so that high hardness can be achieved. On the other hand, stress relaxation caused by microvoids as described later cannot be obtained, and the toughness tends to be lowered.

  By the way, etching processing is known as a surface treatment of a hard alloy. When the surface of the base material before the coating layer is formed by etching is processed, the etching solution corrodes the binding phase (for example, cobalt) on the surface, and there is a slight gap between the particles of the hard phase (for example, tungsten carbide). Can do. Since the coating layer enters the gap to some extent, an excellent effect can be expected regarding the adhesion of the coating layer to the base material. However, since such a small gap is not completely filled even when the coating layer is coated, a relatively large void is generated at the interface between the base material and the coating layer. As a result, there arises a problem that the work material enters the void during cutting to cause abnormal wear.

  On the other hand, blasting is also known as a surface treatment for hard alloys. When the surface of the base material is blasted before forming the coating layer, the surface of the base material is roughened and uneven, so that the columnar crystal grows in various directions, and the crystal growth stops Will increase. As a result, a large amount of microvoids are generated, the hardness is lowered, and the wear resistance is lowered. Further, at the edge portion of the hard phase (for example, tungsten carbide), the crystal of the film formed as the coating layer grows at a large angle (in other words, the crystal growth angle α increases), so that the crystal becomes coarse. This also leads to a reduction in hardness. Furthermore, according to the blasting process, the surface of the base material is in a state where the hard phase (for example, tungsten carbide) particles are crushed and the surface is roughened. There is also a problem that decreases. In addition, since shot blasting performed under general conditions has a large impact force, there is a possibility that the hard phase may be shattered during blasting.

  An object of the present invention is to provide a cutting tool having both excellent wear resistance and fracture resistance.

  As a result of intensive studies to solve the above problems, the inventors of the present invention have made a vertical growth portion in which a crystal is grown on the coating layer almost perpendicularly (at an angle of 85 to 90 degrees) with respect to a plane orthogonal to the thickness direction. And having a multi-directionally grown portion with crystal growth (at an angle of less than 85 degrees) with a relatively large inclination with respect to the plane makes it possible to achieve both high hardness and high toughness, which is excellent. It has been found that it is possible to develop wear resistance and fracture resistance. That is, in the vertical growth portion, microvoids are not generated, and high hardness can be achieved in this region. On the other hand, the multi-directional growth part becomes a region where micro voids are formed as a result of crystals grown with a large inclination colliding with each other. The presence of such microvoided regions is disadvantageous in that the film hardness decreases, but on the other hand, the residual stress is relaxed, the toughness is increased, and the fracture resistance is improved. The advantage is obtained. That is, even when the crack has progressed, the microvoids act as a microcrack in the stress field at the crack tip, and the stress concentration can be relaxed and the progress of the crack can be suppressed, so that high toughness can be achieved. The present invention has been completed based on such findings.

  That is, the present invention has the following configuration.

  (1) A cutting tool comprising a base material and a coating layer formed on the surface of the base material, wherein the coating layer grows at an angle of 85 to 90 degrees with respect to a plane perpendicular to the thickness direction. A vertical growth portion and a multi-direction growth portion which is crystal-grown at an angle of less than 85 degrees with respect to the plane, and in a cross section cut in the thickness direction, a straight line of 20 μm at the interface between the base material and the coating layer is formed. A cutting tool characterized in that the multidirectional growth portion occupies 5 to 40% of the length range.

  (2) A cutting tool including a base material and a coating layer formed on the surface of the base material, wherein the coating layer grows at an angle of 85 to 90 degrees with respect to a plane orthogonal to the thickness direction. A vertical growth portion and a multi-direction growth portion crystal-grown at an angle of less than 85 degrees with respect to the plane, and the width of the multi-direction growth portion in the cross-section cut in the thickness direction is outside the coating layer. A cutting tool characterized by increasing from the surface toward the base material side.

  (3) A cutting tool comprising a base material and a coating layer formed on the surface of the base material, wherein the coating layer grows at an angle of 85 to 90 degrees with respect to a plane perpendicular to the thickness direction. A vertical growth portion and a multi-direction growth portion which is crystal-grown at an angle of less than 85 degrees with respect to the plane, and in a cross section cut in the thickness direction, a straight line on the interface between the base material and the coating layer is 20 μm. A cutting tool characterized in that there are 3 to 40 multi-directional growth parts independent of each other.

  (4) The cutting tool according to any one of (1) to (3), wherein the coating layer has a thickness of 2.0 μm or more.

  (5) The base material has a hard phase and a binder phase that binds the hard phase, and the hard phase is a group consisting of carbides, nitrides, and carbonitrides of Group 4, 5, and 6 metals of the periodic table. The cutting tool according to any one of (1) to (4), wherein the cutting tool is composed of a component that is at least one selected from the group consisting of at least one of titanium carbonitride and tungsten carbide.

  (6) The cutting tool according to any one of (1) to (5), wherein the binder phase includes an iron group metal as a main component.

  (7) The cutting tool according to (5) or (6), wherein the surface of the base material includes a smooth surface portion made of a hard phase and a concave portion made of a binder phase or a binder phase and a hard phase.

  (8) The cutting tool according to (7), wherein the vertical growth portion is formed on the smooth surface portion, and the multidirectional growth portion is formed on the recess.

  According to the present invention, since the residual stress in the coating layer covering the surface of the hard alloy base material is optimized, the coating layer is not only difficult to peel off, but also has high hardness and high toughness, excellent There is an effect that a cutting tool having both wear resistance and fracture resistance can be provided.

  Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is an explanatory view schematically showing a cross section when the cutting tool of the present invention is cut in the thickness direction.

  In the cutting tool of the present invention, a coating layer 20 is formed on the surface of a hard alloy base material 10 composed of a hard phase 11 and a binder phase 12 that binds the hard phase 11.

  The component which comprises the said hard phase 11 will not be restrict | limited especially if it is a raw material generally used for the hard phase in a hard alloy. For example, as a preferred embodiment, the components constituting the hard phase 11 are carbides, nitrides of Group 4, 5, and 6 metals (for example, Ti, Zr, Hf, V, Nb, Mo, Cr, etc.) of the periodic table. , One or more selected from the group consisting of carbonitrides, and at least one of titanium carbonitride and tungsten carbide is preferably essential. Further specific examples of these carbides, nitrides, carbonitrides and the like are not particularly limited.

  On the other hand, the component constituting the binder phase 12 is also a raw material generally used for a binder phase in a hard alloy, and is not particularly limited as long as the hardness is lower than that of the hard phase. For example, as a preferred embodiment, the component constituting the binder phase 12 may be any component containing an iron group metal (for example, Co, Ni, etc.) as a main component. Further specific examples of the iron group metal and the like are not particularly limited.

  The hardness of the hard phase and the binder phase can be measured by a nanoindentation method or the like. When the particle size of the particles constituting the phase is very small, such as fine carbide, it is difficult to measure by the above method, it is possible to estimate the phase hardness by identifying the phase composition by elemental analysis such as WDS It is.

  In the hard alloy base material 10, the hard phase 11 is preferably present in a total volume of 85 to 92% by volume, and the binder phase 12 is preferably present in a ratio of 8 to 15% by volume.

  The hard alloy base material 10 is usually obtained by mixing the raw material powders constituting the hard phase 11 and the binder phase 12 at a predetermined ratio and subjecting the molded powder to a binder removal treatment, and then about 1350 to 1550 ° C. It is obtained by baking for about 0.5 to 3 hours in a vacuum atmosphere.

  The coating layer 20 includes a vertical growth portion 21 crystal-grown at an angle of 85 to 90 degrees (shown as an angle β in FIG. 1) with respect to a plane orthogonal to the thickness direction of the cutting tool, and 85 degrees with respect to the plane. And a multi-directional growth portion 22 that is crystal-grown at an angle less than that (shown by an angle α in FIG. 1). In the vertical growth part 21, since the crystal grows substantially perpendicular to the plane orthogonal to the thickness direction, no microvoids are generated. Therefore, the vertical growth portion 21 is a region having a high hardness. On the other hand, the multi-directional growth part 22 grows crystals with a relatively large inclination (angle α) with respect to the plane perpendicular to the thickness direction of the cutting tool. Then, a void of a level of several tens of nm is formed. In the multidirectional growth portion 22 in which microvoids are formed in this way, even when a crack has progressed, the microvoids act as microcracks in the stress field at the crack tip, and the stress concentration is relaxed and the crack progresses. Therefore, high toughness is expressed.

  In the present invention, the multidirectional growth part 22 is present in a form that satisfies at least one of the following (i), (ii), or (iii). Thereby, the vertical growth part 21 and the multi-directional growth part 22 exist in an optimal balance. As a result, a balance between high hardness and high toughness can be achieved in a balanced manner.

  (I) In the cross section cut in the thickness direction, the multidirectional growth portion 22 occupies 5 to 40% of the length range of a straight line 20 μm at the interface between the base material 10 and the coating layer 20. That is, the straight line at the interface between the base material 10 and the coating layer 20 is a straight line connecting xx in FIG. 1, and if the range indicated by y in FIG. 1 is 20 μm in length, this range The length range z1 in which the multidirectional growth part 22 exists when the straight line is viewed corresponds to 5 to 40% of 20 μm. When there are a plurality of multidirectional growth portions 22 in the length range y, the total of the lengths z1, z2, z3,... Occupying each multidirectional growth portion 22 (however, z2 and subsequent figures are not shown). 2) corresponding to 5 to 40% of 20 μm.

  (Ii) In the cross section cut in the thickness direction, the width of the multidirectional growth portion 22 is increased from the outer surface of the coating layer 20 toward the base material 10 side. That is, when viewed at the interface between the base material 10 and the coating layer 20 (straight line connecting xx) as in the multidirectional growth portion 22 shown in FIG. 1, the width of the multidirectional growth portion 22 is z1. However, when the interface is viewed as a straight line, the width becomes narrower as it moves toward the surface of the coating layer.

  (Iii) In the cross section cut in the thickness direction, 3 to 40 multidirectional growth portions 22 that are independent from each other exist in a straight line 20 μm on the interface between the base material 10 and the coating layer 20. That is, similarly to the above (i), if the range indicated by y in FIG. 1 is 20 μm in length, there are multiple directions that are independent of each other (in other words, surrounded by the vertical growth portion 21). There are 3 to 40 growth portions 22 (only one is shown in FIG. 1).

  The coating layer 20 includes a columnar crystal (I) having a growth direction angle θg of less than 25 degrees at the growth start point and a columnar crystal (II) having a growth direction angle θg of 25 degrees or more at the growth start point. In the cross section cut in the thickness direction, the width of the region occupied by the columnar crystal (I) on the imaginary straight line located on the 0.3 μm coating layer 20 side from the interface between the base material 10 and the coating layer 20 is defined as WaI. When the width of the region occupied by the columnar crystal (II) is WaII, the value of WaII / WaI is preferably 0.1 to 1.0. Thereby, even when the impact is concentrated on the multi-directional growth part, it is possible to avoid the film from being broken or the film peeling or chipping from occurring. The columnar crystal (I) referred to here constitutes the vertical growth portion 21, and the columnar crystal (II) constitutes the multidirectional growth portion 22. Note that the virtual straight line positioned on the 0.3 μm coating layer 20 side with respect to the interface between the base material 10 and the coating layer 20 is a straight line at the interface between the base material 10 and the coating layer 20, that is, between xx in FIG. Is a straight line formed by translating 0.3 μm to the coating layer 20 side.

  In the coating layer 20, in order for the vertical growth part 21 and the multidirectional growth part 22 as described above to exist, the surface of the base material 10 includes the smooth surface part 13 made of the hard phase 11 and the bonding phase 12 or bonding. What is necessary is just to be comprised from the recessed part 14 which has the surface which consists of the phase 12 and the hard phase 11. FIG.

  Since the surface of the base material 10 has a smooth surface portion 13 made of the hard phase 11, in other words, a surface-treated portion that is smooth, the columnar crystal is straight when the coating layer 20 is formed on the smooth surface portion 13. It will grow in line with. That is, the vertical growth part 21 is formed on the smooth surface part 13.

  As a means for providing the smooth surface portion 13 by subjecting the hard phase portion on the surface of the base material 10 to a smooth surface, for example, brush polishing is preferably mentioned. As the brush used in the brush polishing process, those having long hairs are preferable. Specifically, a brush such as a cup brush, a wheel brush, or a roll brush is preferably used. When performing brush polishing, it is common to use diamond abrasive grains. However, if abrasive grains made of silicon carbide (SiC) are used, polishing scratches caused by the polishing process are reduced, resulting in a smoother surface. Since it will be in a state, it is preferable. Moreover, in order to obtain a smooth processed surface, it is preferable to set the number of abrasive grains to be # 400 or more. In particular, in order to increase processing efficiency, it is preferable to use abrasive grains of # 500 to # 2000. .

  On the other hand, when the coating layer 20 is formed in the recess 14 by forming the recess 14 having a surface composed of the binder phase 12 or the binder phase 12 and the hard phase 11 on the surface of the base material 10, Since the columnar crystal of the portion grows so as to be focused, there are many portions where the crystal growth stops, and micro voids (in this case, a void of a level of several tens of nanometers) are formed due to defects between the growth of the crystals. . That is, the multidirectional growth part 22 is formed on the concave part 14. In addition, the concave portion 14 existing on the surface of the base material 10 is composed of the binder phase 12 or the binder phase 12 and the hard phase 11. In other words, this is at least part of the surface of the concave portion 22. It also means that a binder phase is present. In particular, it is desirable that at least the bottom surface of the surface of the recess 14 has a binder phase. Furthermore, it is more preferable that the surface of the recess 14 is composed only of the binder phase 12.

  In addition, the surface of the recessed part 14 here consists of the binder phase 12 or the binder phase 12 and the hard phase 11 means that the surface of the recess 14 substantially consists of the binder phase 12, the binder phase 12 and the hard phase 11, It may contain components that are inevitable in production.

  As a means for forming the recess 14, it is preferable that the entire surface of the base material 10 is smoothed by the brush polishing process, and then the shot phase is applied to remove the binder phase 12. In performing this shot blasting, by using abrasive grains softer than the hard phase 11 (for example, WC), the bonded phase 12 is maintained while maintaining the smoothness formed by brush polishing in the hard phase 11 portion. A recess shape can be formed by removing a portion (for example, Co). The shape of the recess 14 formed in this way is, for example, rounder at the bottom than the recess formed by etching, and is very shallow, and is deeply cut into the interior as in etching. The shape will not be. As a result, the above-described wrinkles between the growth of the crystals tend to occur, and as a result, the toughness is easily improved.

  The hardness of the abrasive grains can be measured by various measuring methods for measuring the hardness of the powder, and the unit of hardness is appropriately selected depending on the measuring method, such as Brinell hardness (HB), Vickers hardness (HV), etc. obtain.

The shot blasting may be performed by a dry method in which abrasive grains are jetted together with air or the like, or may be performed by a wet method in which abrasive grains are jetted and processed simultaneously with a liquid (solvent). As abrasive grains to be used, abrasive grains generally used in processing, specifically, abrasive grains such as aluminum oxide (Al ₂ O ₃ ), silicon carbide (SiC), and diamond can be used. In order to remove only the binder phase by shot blasting, those having relatively low hardness and high specific gravity such as chromium oxide (Cr ₃ O ₂ ) and zirconium oxide (ZrO ₂ ) are preferable. In addition, when performing shot blasting in a wet manner, a solvent used in general wet blasting, such as water, can be used as a solvent. As conditions for performing shot blasting, conditions weaker than general processing, specifically, an injection pressure of 0.1 to 0.7 MPa, an injection angle of 30 to 60 °, a workpiece and an injection nozzle, The distance is preferably 2 to 5 cm, and the count of the abrasive grains is preferably # 360 to # 1000.

  As described above, in the present invention, the vertical growth portion 21 existing in the coating layer 20 becomes a hardened region, while the multidirectional growth portion 22 existing in the coating layer 20 has microvoids to increase the toughness. It becomes the area. That is, the cutting tool according to the present invention has both the hardened region and the toughened region in the coating layer 20, and therefore maintains both of the contradicting excellent characteristics. As a result, it is possible to achieve both excellent wear resistance and fracture resistance. In addition, the above-described microvoids present in the present invention are very small voids, and thus there is no possibility of affecting the wear resistance. Moreover, in the present invention, the anchoring effect due to the unevenness can be obtained by the recesses present on the surface of the hard alloy base material, so that the adhesion between the coating layer and the base material is also high.

  In the present invention, the multi-directionally grown portion occupies a certain range (that is, a length range of a straight line of 20 μm at the interface) in a cross section obtained by cutting the coating layer 20 in the thickness direction (that is, a cross section substantially perpendicular to the surface of the cutting tool). Multi-directional growth independent of each other in a ratio of 22 (requirement (i) above), change in the width of the multi-directional growth portion 22 (requirement (requirement (ii) above)), and a certain range (that is, a length range of a straight line of 20 μm at the interface). When measuring the number of the parts 22 (requirement of (iii) above) or the values of WaI and WaII described above, for example, the cross section is 5000 times using a scanning electron microscope (SEM) or a transmission electron microscope (TEM). What is necessary is just to observe by the magnification of -20,000 times.

The composition of the coating layer 20 formed on the surface of the hard alloy base material 10 is not particularly limited. For example, titanium carbide (TiC), titanium carbonitride (TiCN), titanium nitride (TiN), aluminum nitride One or more selected from carbides, nitrides, carbonitrides and oxides of metals of Group 4, 5, 6 and aluminum (Al) in the periodic table such as titanium (TiAlN) and aluminum oxide (Al ₂ O ₃ ). It is composed of a layer or multiple layers formed.

  The film thickness of the coating layer 20 is preferably 2.0 μm or more, more preferably 3.0 to 20.0 μm.

  The coating layer 20 can be formed by a conventionally known method such as a chemical vapor deposition method (CVD method), a sputtering method, an ion plating method, or a physical vapor deposition method (PVD method) such as a vapor deposition method. Note that it is preferable to use a medium temperature chemical vapor deposition method (MT-CVD method) because it is easy to obtain the structure of the present invention.

Specifically, to form a columnar titanium carbonitride (TiCN) layer, the reaction gas composition is 0.1 to 10% by volume of titanium chloride (TiCl ₄ ) gas and 0 to nitrogen (N ₂ ) gas. 40% by volume, 1% to 10% by volume of acetonitrile (CH ₃ CN) gas, and the remaining mixed gas consisting of hydrogen (H ₂ ) gas were sequentially adjusted. The temperature inside the chamber was 750 to 900 ° C., and the pressure was 5 to 85 kPa. Adjust so that Moreover, it is good also as a multilayer structure which forms another hard film | membrane into the upper layer or lower layer of columnar titanium carbonitride.

  Here, a film forming method as an example of another film quality will be described.

First, to form a titanium nitride (TiN) layer, the reaction gas composition is 0.1 to 10% by volume of titanium chloride (TiCl ₄ ) gas, 5 to 60% by volume of nitrogen (N ₂ ) gas, and the rest A mixed gas composed of hydrogen (H ₂ ) gas is sequentially adjusted, and the inside of the chamber is adjusted to have a furnace temperature of 800 to 1100 ° C. and a pressure of 5 to 85 kPa.

Next, in order to form a granular titanium carbonitride (TiCN) layer, the reaction gas composition is titanium chloride (TiCl ₄ ) gas of 1.0 to 6.0% by volume and nitrogen (N ₂ ) gas of 5 to 5. 40% by volume, 1 to 15% by volume of methane (CH ₃ ) gas and the remaining mixed gas consisting of hydrogen (H ₂ ) gas were sequentially adjusted, and the chamber temperature was 950 to 1100 ° C. and the pressure was 5 to 85 kPa. Adjust so that

Further, in order to form a titanium carbonitride (TiCNO) layer, titanium chloride (TiCl ₄ ) gas is 0.1 to 6% by volume, methane (CH ₄ ) gas is 0.1 to 10% by volume, carbon dioxide ( A mixed gas consisting of 0.5 to 5% by volume of CO ₂ ) gas, 5 to 60% by volume of nitrogen (N ₂ ) gas, and the remaining hydrogen (H ₂ ) gas is prepared and introduced into the reaction chamber, The inside is adjusted to 800 to 1100 ° C. and 5 to 30 kPa.

In order to form an aluminum oxide (Al ₂ O ₃ ) layer, 1.0 to 10% by volume of aluminum chloride (AlCl ₃ ) gas and 0.5 to 3.5% by volume of hydrogen chloride (HCl) gas are used. Carbon dioxide (CO ₂ ) gas is used in a mixed gas of 0.5 to 5.0% by volume, hydrogen sulfide (H ₂ S) gas is 0 to 0.5% by volume, and the remainder is hydrogen (H ₂ ) gas. , 900 to 1100 ° C. and 5 to 10 kPa.

Finally, to form a titanium nitride (TiN) layer, the reaction gas composition is 0.1 to 10% by volume of titanium chloride (TiCl ₄ ) gas, 5 to 60% by volume of nitrogen (N ₂ ) gas, and the rest Adjusts the mixed gas composed of hydrogen (H ₂ ) gas so that the temperature in the chamber is 800 to 1100 ° C. and the pressure is 5 to 85 kPa.

  The cutting tool of the present invention is useful as a cutting tool such as various types of turning such as outer shape, inner diameter, grooving, threading, and parting off, milling, drill, end mill, etc., among others, cutting used for turning, milling, and drilling. Suitable for tools, especially as a turning tool for interrupted machining and unstable machining.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further in detail, this invention is not limited to a following example.

(Example)
6% by mass of metallic cobalt (Co) powder with an average particle size of 1.5 μm and 0% titanium carbide (TiC) powder with an average particle size of 1.5 μm with respect to tungsten carbide (WC) powder with an average particle size of 1.5 μm. 0.5% by mass, tantalum carbide (TaC) powder was added and mixed at a rate of 1% by mass, and formed into a cutting tool shape (CNMA1204112) by press molding. Thereafter, a binder removal treatment was performed, and the hard alloy base material was produced by holding and firing at 1500 ° C. for 1 hour in a vacuum of 0.01 Pa.

Next, roughing and finishing shown in Table 1 were sequentially performed on the surface of the base material. Conditions for each processing are as shown in Table 2. After that, by chemical vapor deposition on the surface of the base material subjected to each processing,
A hard film (total film thickness: 12.0 μm) composed of a titanium nitride (TiN) layer, a columnar titanium carbonitride (TiCN) layer, and an aluminum oxide (Al ₂ O ₃ ) layer was formed to produce a cutting tool.

The film formation conditions of the titanium nitride (TiN) layer are as follows: film formation temperature 880 ° C., pressure 200 mbar, titanium tetrachloride (TiCl ₄ ) 1.5 vol%, nitrogen (N ₂ ) 20 vol%, and the rest hydrogen (H ₂ ) It is.

The film formation conditions for the columnar titanium carbonitride (TiCN) layer by the medium temperature chemical vapor deposition method were film formation temperature 860 ° C., pressure 90 mbar, titanium tetrachloride (TiCl ₄ ) 1.5 vol%, and acetonitrile (CH ₃ CN) 0 .6 vol%, nitrogen (N ₂ ) is 30 vol%, and the remainder is hydrogen (H ₂ ).

The film formation conditions of the aluminum oxide (Al ₂ O ₃ ) layer are as follows: film formation temperature 1010 ° C., pressure 90 mbar, aluminum trichloride (AlCl ₃ ) 1.6 vol%, carbon dioxide (CO ₂ ) 3.5 vol%, sulfide Hydrogen (H ₂ S) is 0.1 vol%, and the remainder is hydrogen (H ₂ ).

Regarding the thickness of each layer, from the substrate side, a titanium nitride (TiN) layer (thickness: 0.3 μm) —a titanium carbonitride (TiCN) layer composed of columnar crystals (8.0 μm thickness) —a titanium carbonitride composed of granular crystals (TiCN) Layer (0.1 μm thickness) -titanium carbonitride (TiCNO) layer (0.1 μm thickness) -aluminum oxide (Al ₂ O ₃ ) layer (3.0 μm thickness) -titanium nitride (TiN) layer (0.5 μm thickness) The films were formed in this order.

  About each obtained cutting tool, when it cut | disconnects in the thickness direction of a hard alloy base material and a coating layer, and the cross section was observed with the magnification of 10000 times using the transmission electron microscope (TEM), the length of 20 micrometers of straight lines in an interface The ratio of the multidirectional growth part to the range, the change of the width of the multidirectional growth part (that is, “○” if the base material side> the coating layer surface side, “×” otherwise), straight line at the interface Table 1 shows the number of independent multidirectional growth portions in the length range of 20 μm and the ratio of WaII to WaI described above.

  Using the cutting tool, a continuous cutting test and a strong interrupted cutting test were performed under the following conditions, and the wear resistance was evaluated by the continuous cutting test and the fracture resistance was evaluated by the strong interrupted cutting test. The results of this cutting test are shown in Table 3.

(Continuous cutting test conditions)
Work material: SCM435
Tool shape: CNMG120408
Cutting speed: 300 m / min Feeding speed: 0.3 mm / rev
Cutting depth: 2mm
Cutting time: 20 minutes Cutting fluid: Mixture of 15% emulsion + 85% water Evaluation item: Observe the cutting edge with a microscope and measure the amount of flank wear and tip wear (strong intermittent cutting test conditions)
Work Material: SCM440 Four Groove Material Tool Shape: CNMG120408
Cutting speed: 300 m / min Feed speed: 0.4 mm / rev
Cutting depth: 2mm
Cutting fluid: Mixture of 15% emulsion + 85% water Evaluation item: Number of impacts leading to defects

  As can be seen from Table 1 and Table 2 above, the sample No. 1 of the present invention was subjected to predetermined brushing as roughing and predetermined blasting as finishing. As for 1-7, it can be seen that the ratio of the multidirectional growth portion in the length range of 20 μm in a straight line at the interface is 5 to 40%. Sample No. 1-7 indicates that the number of multi-directional growth portions independent of each other is in the range of 3 to 40. Sample No. In 1-7, the change in the width of the multidirectional growth portion is such that the base material side> the coating layer surface side (in other words, the width increases from the outer surface of the coating layer toward the base material side). I understand. Furthermore, sample no. In 1-7, the width of the region occupied by the columnar crystal whose growth direction angle θg is less than 25 degrees at the growth start point is WaI, and the region occupied by the columnar crystal whose growth direction angle θg is 25 degrees or more at the growth start point is When the width was WaII, the value of WaII / WaI was included in the range of 0.1 to 1.0.

  Further, as can be seen from Table 3, the ratio of the multi-directional growth portion occupying the length range of 20 μm of the straight line at the interface, the number of multi-directional growth portions independent of each other, and the change in the width of the multi-directional growth portion respectively. Sample No. within the range. For samples 1-7, each of the sample Nos. Described above is outside the scope of the present invention. Compared to 8-10, excellent results were obtained in all the number of impacts leading to flank wear, tip wear, and fracture.

  This is because the high-toughness multi-directional growth part exists at an optimal level, so it was possible to combine high hardness and high toughness, so that cracks occurred in the coating layer during a strong impact in hard interrupted processing. Even in this case, it is considered that the generation of cracks was suppressed and the chipping could be prevented.

It is explanatory drawing which showed typically the cross section when the cutting tool of this invention was cut | disconnected in the thickness direction.

Explanation of symbols

10: Base material 11: Hard phase 12: Bonded phase 13: Smooth surface portion 14: Concave portion 20: Cover layer 21: Vertical growth portion 22: Multidirectional growth portion

Claims (8)

A cutting tool comprising a base material and a coating layer formed on the surface of the base material,
The coating layer includes a vertical growth portion that is crystal-grown at an angle of 85 to 90 degrees with respect to a plane orthogonal to the thickness direction, and a multi-direction growth portion that is crystal-grown at an angle of less than 85 degrees with respect to the plane. And
A cutting tool characterized in that a multidirectional growth portion occupies 5 to 40% of a length range of a straight line of 20 μm at an interface between a base material and a coating layer in a cross section cut in a thickness direction. A cutting tool comprising a base material and a coating layer formed on the surface of the base material,
The coating layer includes a vertical growth portion that is crystal-grown at an angle of 85 to 90 degrees with respect to a plane orthogonal to the thickness direction, and a multi-direction growth portion that is crystal-grown at an angle of less than 85 degrees with respect to the plane. And
A cutting tool characterized in that, in the cross section cut in the thickness direction, the width of the multidirectional growth portion increases from the outer surface of the coating layer toward the base material side. A cutting tool comprising a base material and a coating layer formed on the surface of the base material,
The coating layer includes a vertical growth portion that is crystal-grown at an angle of 85 to 90 degrees with respect to a plane orthogonal to the thickness direction, and a multi-direction growth portion that is crystal-grown at an angle of less than 85 degrees with respect to the plane. And
A cutting tool characterized in that, in a cross section cut in the thickness direction, 3 to 40 multidirectional growth portions independent from each other exist in a straight line of 20 μm on an interface between a base material and a coating layer.   The cutting tool in any one of Claims 1 thru | or 3 whose film thickness of the said coating layer is 2.0 micrometers or more.   The base material has a hard phase and a binder phase that binds the hard phase, and the hard phase is selected from the group consisting of carbides, nitrides, and carbonitrides of Group 4, 5, and 6 metals of the periodic table. The cutting tool according to any one of claims 1 to 4, wherein the cutting tool is composed of one or more components and at least one of titanium carbonitride and tungsten carbide.   The cutting tool according to claim 5, wherein the binder phase contains an iron group metal as a main component.   The cutting tool according to claim 5 or 6, wherein the surface of the base material includes a smooth surface portion made of a hard phase and a concave portion made of a binder phase or a binder phase and a hard phase.   The cutting tool according to claim 7, wherein the vertical growth portion is formed on the smooth surface portion, and the multidirectional growth portion is formed on the concave portion.

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