JP2007229821A - Surface-coated cutting tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface-coated cutting tool with a long life in cut processing including high-speed intermittent processing. <P>SOLUTION: A titanium compound including oxygen consists of needle-like crystal grains with an aspect ratio of 8-100 viewed from a cross section parallel to a substrate surface, and a complex area of a titanium compound phase including oxygen and a non-oxide phase exists in an area near an interface between the titanium compound phase including oxygen and the non-oxide phase on the upper layer. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a surface-coated cutting tool having excellent cutting resistance such as fracture resistance and wear resistance, in which a hard coating layer is formed on the surface.

  Along with the recent improvement in casting technology, thinning and complex shapes are progressing due to the progress of near-net shaping of work materials and the development of high-strength materials. In addition, as cutting efficiency increases in recent years, high-speed cutting with high cutting speed is increasing, and the cutting edge may become very hot even under cutting conditions using a cutting fluid. Furthermore, in order to process a complex shape, there is an increasing number of cases in which high-speed cutting is performed on a composite processing portion including hard interrupted processing and continuous processing.

Conventionally, a hard coating layer composed of a single layer or multiple layers such as a TiC layer, a TiN layer, a TiCN layer, an Al ₂ O ₃ layer and a TiAlN layer is applied to the surface of a hard substrate such as cemented carbide, cermet or ceramics. The formed surface-coated cutting tool is frequently used.

However, in such a conventional surface-coated cutting tool, when high-speed cutting is performed on a composite processed part, Al ₂ O ₃ is peeled off at a high temperature stability but poor in adhesion, and diffusion wear of the TiCN film is poor in oxidation resistance. It was observed. This triggers peeling of the hard coating layer and boundary damage, and there is a problem that it is difficult to extend the tool life due to tool damage such as chipping of the cutting edge and occurrence of abnormal wear.

  On the other hand, Patent Document 1 and Patent Document 2 disclose that the use of a TiCN film made of columnar crystals as the hard coating layer improves the chipping resistance and chipping resistance as a cutting tool.

Patent Documents 3 and 4 disclose that a needle-like TiCNO film is formed as an intermediate layer between the TiCN film and the Al ₂ O ₃ film to improve the adhesion of the Al ₂ O ₃ film. ing.
Japanese Patent Laid-Open No. 6-8008 Japanese Patent Laid-Open No. 6-8010 JP 2004-148503 A JP 2004-74324 A

  However, when a columnar crystal TiCN film is introduced into the hard coating layer as described in Patent Document 1 and Patent Document 2, the chip resistance and chipping resistance are improved due to the columnar TiCN having excellent strength. However, since the oxidation resistance cannot be said to have been improved, the diffusion wear phenomenon due to the high temperature of the cutting edge is not suppressed, and the wear resistance is drastically lowered when dry machining or high-speed cutting of the composite machining part is performed. There was a problem that the lifetime was shortened.

Furthermore, as described in Patent Document 3 and Patent Document 4, by depositing an intermediate layer having needle-like particles in the binder phase, a large number of protrusions are generated on the surface of the intermediate layer, and the Al ₂ O ₃ film and the intermediate layer When α-type Al ₂ O ₃ with excellent adhesion is introduced, the wear resistance at high temperature is improved due to α-type Al ₂ O ₃ with excellent high-temperature stability. However, it cannot be said that it is sufficient due to the impact force at the time of hard interrupted machining, so the problem is that chipping resistance and chipping resistance are reduced and tool life is shortened when dry machining or high-speed cutting of composite parts. was there.

  The present invention has been made to solve the above-described problems, and its purpose is to provide excellent wear resistance and fracture resistance even in dry cutting and high-speed cutting in a composite processed portion. The object is to provide a long-life surface-coated cutting tool.

  The present inventor has improved the impact resistance under high-temperature conditions by introducing a coating layer having high strength and excellent oxidation resistance into the surface-coated cutting tool. It is possible to prevent peeling of hard coating layer and diffuse wear due to intermittent cutting, and to be a surface-coated cutting tool that exhibits excellent wear resistance and fracture resistance even in dry cutting and high-speed cutting in composite processed parts. I found out.

  That is, the surface-coated cutting tool of the present invention is a surface-coated cutting tool in which a hard coating layer composed of a plurality of layers is deposited on the surface of a substrate, and the hard coating layer includes a titanium compound phase containing oxygen, An oxygen-containing titanium compound phase and a non-oxide phase comprising at least one compound selected from the group consisting of carbides, nitrides, and carbonitrides of Group 4 elements, and the titanium compound containing oxygen is And composed of needle-like crystal particles having an aspect ratio in the range of 8 to 100 in a cross-sectional view parallel to the substrate surface, and in the vicinity of the interface between the titanium compound phase containing oxygen and the non-oxide phase In the region, the surface-coated cutting tool is characterized in that a complex region of the titanium compound phase containing oxygen and the non-oxide phase exists.

  Here, the crystal grain of the titanium compound containing oxygen has an average crystal height of 1 to 10 μm in a cross-sectional view perpendicular to the surface of the substrate, thereby further improving the wear resistance and fracture resistance of the cutting tool. Desirable because it can.

Furthermore, the titanium compound containing oxygen contains Ti ₂ O ₃ and the non-oxide phase is preferably made of at least one of TiCN and TiN, so that the oxidation resistance can be improved.

  The crystal grain of the titanium compound containing oxygen has an average major axis width of 1 to 4 μm and an average minor axis width of 0.03 to 0.5 μm in a cross-sectional view parallel to the substrate surface. This is desirable in terms of improving strength and suppressing chipping and defects.

  Further, the non-oxide phase is a titanium nitride layer as a surface layer of the hard coating layer, and the titanium compound containing oxygen is exposed and the titanium compound containing oxygen is exposed on the intersection of the upper surface and the side surface of the substrate. The titanium nitride layer is polished so as to leave a part of the titanium nitride layer so as to be exposed, so that the cutting edge becomes smooth and the protrusions of particles that can cause chipping and sudden defects This is desirable in that the depressions are reduced and the occurrence of chipping and sudden defects is more effectively suppressed.

  In addition, when the maximum height Rz of the surface of the hard coating layer is 0.5 to 1.5 μm, it is desirable in that the cutting edge becomes stable and chipping and chipping are suppressed.

  The surface-coated cutting tool of the present invention is a hard coating layer having a structure in which two or more multilayer films are laminated on the surface of a substrate, and has better oxidation resistance and impact resistance as an inner layer adjacent to the surface layer. High-aspect-ratio acicular crystals of oxygen-containing titanium compounds are arranged, and a non-oxide phase is formed as a surface layer so as to fill the gaps between the acicular crystal grains, thereby providing strong impact at high temperatures. Even if it is applied, the high-aspect ratio needle-like crystal is not easily broken and is not easily oxidized, so that excellent wear resistance and fracture resistance can be obtained.

  Therefore, even in processing that requires oxidation resistance and chipping resistance, it is possible to prevent wear and chipping of the entire coating layer without causing diffusion wear and damage to the coating layer.

  In particular, severe impact is applied to tool cutting edges such as high-speed heavy interrupted cutting of metals such as cast iron in which high-hardness graphite particles are dispersed, such as gray cast iron (FC material) and ductile cast iron (FCD material). High-strength acicular crystals exist even under severe cutting impact on the hard coating layer under cutting conditions or even combined cutting conditions combining these intermittent cutting and continuous cutting. As a result, the hard coating layer can withstand impacts without chipping or chipping. As a result, the entire hard coating layer can be prevented from chipping and peeling, and an excellent cutting tool that maintains wear resistance can be obtained. It is done. Of course, even in steel cutting, the tool is superior in fracture resistance and wear resistance to conventional tools.

  The titanium compound containing oxygen is controlled to be acicular crystal particles having an aspect ratio in the range of 8 to 100 in a cross-sectional view parallel to the substrate surface, and a non-oxide is embedded between the acicular crystal particles. By being formed in this way, it is possible to provide chipping resistance at high temperatures without the work material entering the gaps between the high aspect ratio crystals having high strength during cutting. Furthermore, since it contains oxygen, crater wear on the rake face can also be suppressed due to excellent oxidation resistance.

  Further, when the average crystal height in a cross-sectional view perpendicular to the substrate surface is 1 to 10 μm, both chipping resistance and wear resistance can be appropriately provided.

Furthermore, the titanium compound containing oxygen contains Ti ₂ O ₃ , and since Ti ₂ O ₃ is an oxide, it has excellent oxidation resistance. Furthermore, when the non-oxide phase is made of at least one of TiCN and TiN, titanium atoms improve the bonding force between the oxide and the non-oxide, thereby improving the chipping resistance caused by film peeling. I can do it.

  In addition, if the crystal grains of the titanium compound containing oxygen have an average major axis width of 1 to 4 μm and an average minor axis width of 0.03 to 0.5 μm in a cross-sectional view parallel to the substrate surface, the substrate surface Even when viewed in a cross-section parallel to the crystal grains, high-aspect-ratio crystal grains are present, and the presence of these high-aspect-ratio crystal grains at random provides excellent chipping resistance in order to suppress crack propagation and increase toughness.

  Further, the outermost layer of the hard coating layer is a titanium nitride layer, and the titanium nitride layer is left so that the titanium compound containing oxygen is exposed and complexed with the titanium compound containing oxygen. When exposed to polishing, the presence of a titanium nitride layer with low friction near the cutting edge and a titanium compound containing oxygen with excellent oxidation resistance allows for smooth chip discharge due to low friction. In addition, since the diffusion wear is suppressed in order to have excellent oxidation resistance, the wear resistance on the rake face is improved. Furthermore, since titanium nitride is present on the surface layer, the used corner can be easily identified.

  In addition, in the case where the maximum height Rz of the surface of the hard coating layer is in the range of 0.5 to 1.5 μm, since chip slip on the rake face is improved, chip discharge is performed smoothly. , Wear resistance is improved.

  1 is an enlarged cross-sectional view of a main part of a throw-away tip type cutting tool (hereinafter, the surface-coated cutting tool of the present invention may be simply abbreviated as a tool) 1 according to an example of an embodiment of a surface-coated cutting tool of the present invention. FIG. 1 is a substitute photograph), FIG. 2 is an enlarged cross-sectional view of the main part in a state where even a titanium compound phase containing oxygen is formed as a hard coating layer on the substrate surface (drawing substitute photograph) in FIG. A description will be given with reference to FIG. 3 which is a drawing (a photograph substituted for a drawing).

  The tool 1 of the present invention is formed by forming a hard coating layer 3 on the surface of a base 2.

  Here, according to the present invention, the hard coating layer 3 includes a titanium compound phase (hereinafter referred to as an oxygen-containing phase) 4 containing oxygen, and a carbide of a group 4 element adjacent to the titanium compound phase containing oxygen, A non-oxide phase 5 made of at least one compound selected from the group of nitrides and carbonitrides is included, and the oxygen-containing phase 4 has an aspect ratio of 8 to 100 in a cross-sectional view substantially parallel to the surface of the substrate 2. And in the region near the interface between the oxygen-containing phase 4 and the non-oxide phase 5, the oxygen-containing phase 4 and the non-oxidized phase are composed of acicular crystal particles (hereinafter referred to as needle-like particles) 6. A complex region 7 with the physical phase 5 is present.

  In order to produce the complex region 7, for example, an acicular particle layer 8 composed of acicular particles composed of a titanium compound containing oxygen and an upper layer 9 composed of a group 4 element compound not containing oxygen are successively continued. Is possible by stacking.

  Since the acicular particle layer 8 contains oxygen and has a fine shape, it has high strength and excellent oxidation resistance, but there are many gaps between particles as shown in FIG. By filling the gap with the upper layer 9 made of a non-oxidizing compound, welding of the work material during cutting can be prevented, and the excellent strength and oxidation resistance of the acicular particle layer 8 can be exhibited.

  That is, if the upper layer 9 does not fill the gap between the needle-like particle layers 8, the work material is welded by the melted material and chips of the work material entering the gap, and film peeling and chipping of the blade edge occur. End up.

  In addition, when the aspect ratio of the acicular particles 6 in a cross-sectional view parallel to the surface of the substrate 2 is less than 8, the strength of the acicular particle layer 8 becomes insufficient and damage such as a sudden defect occurs.

  On the other hand, when the aspect ratio exceeds 100, the gaps between the needle-like particles 6 become too large, and the work material is welded without being able to fill the gaps only by forming the upper layer 9. Film peeling or chipping of the blade edge occurs.

  In the present invention, the method of measuring the average crystal width in cross-sectional view parallel to the substrate surface of the titanium compound particles 10 containing oxygen in the form of needle crystals is a film removal process up to the center of the crystal height with respect to the film thickness direction. The center of each acicular crystal in the long axis direction is obtained by elemental mapping of the cross-section including the hard coating layer 3 by X-ray microanalyzer (EPMA), Auger electron spectroscopy (AES), transmission electron microscope image (TEM), etc. The short axis width measured at a position is set as a value w1, the long axis width of each acicular crystal is set as w2, and a value obtained by the formula w2 / w1 is set as an aspect ratio. In addition, the long axis is the three-point average value at an arbitrary place for the crystal observed the longest in the observation field of 3000 to 5000 times, and the short axis is the three-point average value in the 5000 times observation field.

  Here, when the oxygen-containing titanium compound particles 10 are measured by the above-described method, the average crystal height h in a cross-sectional view perpendicular to the substrate surface is 1 to 10 μm, particularly 2 to 7 μm. It is desirable to increase the wear resistance and fracture resistance of cutting tools.

  In the present invention, the method for measuring the average crystal height in a cross-sectional view perpendicular to the substrate surface of the titanium compound particles 10 containing oxygen in the form of needle crystals is a scanning electron microscope for the cross section including the hard coating layer 3. The height measured by elemental mapping using (SEM) photograph (FIG. 2), X-ray microanalyzer (EPMA), Auger electron spectroscopy (AES), transmission electron microscope image (TEM), etc. is defined as value h. In addition, it is set as the average value of the values measured at 10 points at arbitrary locations.

  Further, when the titanium compound particles 10 are measured by the above method, the average major axis width in a cross-sectional view parallel to the substrate surface is 1 to 4 μm, particularly 1.5 to 3 μm, and the average minor axis width is 0.03. It is desirable that the thickness be in the range of ˜0.5 μm, particularly 0.07 to 0.3 μm, from the viewpoint of improving the strength as a crystal structure and suppressing chipping and defects.

Here, the oxygen-containing phase 4 is oxidized by containing a compound containing titanium and oxygen, for example, titanium oxide (Ti ₂ O ₃ , TiO ₂ ), titanium carbonate (TiCO), titanium nitride oxide (TiNO), and the like. Excellent wear resistance can be exhibited in dry high-speed cutting that tends to become high temperature due to the extremely excellent oxidation resistance of the object.

  Furthermore, when the non-oxide phase 5 is made of at least one of TiCN and TiN, the titanium atoms improve the bonding force between the oxide and the non-oxide, thereby improving the chipping resistance caused by film peeling. I can do it.

  Further, the non-oxide phase 5 is made of titanium nitride as a surface layer of the hard coating layer 3. The oxygen-containing phase 4 is exposed and the non-oxide phase 5 is exposed at the intersection of the upper surface and the side surface of the substrate 2, that is, on the cutting edge. The titanium nitride layer is polished so as to leave a part of the titanium nitride layer exposed so that the cutting edge becomes smooth, reducing protrusions and dents that can cause tool damage. This is desirable in terms of suppressing chipping more effectively.

  Further, a titanium nitride layer is formed as a surface layer of the hard coating layer so that the titanium compound containing oxygen is exposed and part of the titanium nitride layer is exposed so as to be complexed with the titanium compound containing oxygen. When it is polished, the presence of titanium nitride with a small friction coefficient near the cutting edge and an oxygen-containing titanium compound with excellent oxidation resistance makes it possible to prevent chips from slipping on the rake face due to low friction. This improves the wear resistance on the rake face because it improves the chip discharge smoothly and suppresses the diffusion wear because of excellent oxidation resistance. Furthermore, the presence of titanium nitride on the surface layer is desirable in that the used corners can be easily identified.

  In addition, when the maximum height Rz of the outermost surface of the hard coating layer is in the range of 0.5 to 1.5 μm, as described above, the slip property of the chips on the surface of the coating layer is further improved. It is desirable because abnormal wear does not occur because the discharge becomes smoother. In particular, in addition to the maximum height Rz of the outermost surface of the hard coating layer, when the arithmetic average roughness Ra of the outermost surface of the hard coating layer is in the range of 0.05 to 0.3 μm, chip discharge is further reduced. It can be easily adjusted to a good state.

  Here, as a method for measuring the maximum height Rz of the surface of the hard coating layer 3, it may be measured using a stylus type surface roughness measuring instrument in accordance with JIS B0601'01, and such measurement is difficult. In this case, the measurement can be performed by using a measuring instrument such as a laser microscope or an atomic force microscope to estimate the uneven shape on the surface 5 of the hard coating layer 3 while scanning. In the measurement of the surface roughness (Rz, Ra), when a stylus type surface roughness measuring device is used, a cut-off value: 0.25 mm, a reference length: 0.8 mm, a scanning speed: 0.1 mm Measured at / second.

In addition, as the base | substrate 2 used for the tool 1 of this invention, tungsten carbide (WC), titanium carbide (TiC), or titanium carbonitride (TiCN), and the carbide | carbonized_material of the 4th, 5th, 6th group metal of a periodic table depending on necessity. A cemented carbide or cermet in which a hard phase composed of at least one selected from the group of nitrides and carbonitrides is bonded with a binding phase composed of an iron group metal of cobalt (Co) and / or nickel (Ni), Or hard materials such as silicon nitride (Si ₃ N ₄ ), aluminum oxide (Al ₂ O ₃ ) ceramic sintered body, cubic boron nitride (cBN), ultra-hard sintered body mainly composed of diamond, or carbon steel High hardness materials such as metals such as high-speed steel and alloy steel may be used. In the example shown in FIG. 1, the substrate 2 is made of a cemented carbide composed of a hard phase mainly composed of tungsten carbide (WC) and a binder phase composed of cobalt (Co). When the substrate 2 is made of a cemented carbide, the balance between hardness and toughness is good, and stable cutting can be performed even during high speed dry cutting or cast iron processing.

(Method for producing surface-coated cutting tool of the present invention)
In order to manufacture the above-described surface-coated cutting tool 1 of the present invention, first, a metal powder is added to an inorganic powder such as a metal carbide, nitride, carbonitride, or oxide that can be formed by firing the hard alloy described above. , Carbon powder, etc., are added and mixed as appropriate, and after molding into a predetermined tool shape by a known molding method such as press molding, cast molding, extrusion molding, cold isostatic pressing, etc., in vacuum or non-oxidizing By baking in an atmosphere, the substrate 2 made of the hard material described above is produced. Then, the surface of the base 2 is subjected to polishing or honing of the cutting edge as desired.

  Next, the coating layer 3 is formed on the surface by, for example, chemical vapor deposition (CVD).

First, as a reaction gas composition, titanium chloride (TiCl ₄ ) gas is mixed at 1.0 to 4.0% by volume, nitrogen (N ₂ ) gas is at 5.0 to 60% by volume, and the remainder is hydrogen (H ₂ ) gas The gas is adjusted and introduced into the reaction chamber, and a TiN layer as a base layer is formed in the chamber under conditions of 800 to 900 ° C. and 10 to 30 kPa.

Next, for example, as a reaction gas composition, titanium chloride (TiCl ₄ ) gas is 1.0 to 4.0 volume%, nitrogen (N ₂ ) gas is 0 to 60 volume%, and acetonitrile (CH ₃ CN) is volume%. A mixed gas consisting of 0.1 to 2.0% by volume of gas and the remainder consisting of hydrogen (H ₂ ) gas was prepared and introduced into the reaction chamber, and the film formation temperature was 780 to 880 ° C. at 5 to 20 kPa. A titanium nitride layer is formed.

Next, the reaction gas composition is 0.1 to 3% by volume of titanium chloride (TiCl ₄ ) gas, 0.1 to 10% by volume of methane (CH ₄ ) gas, 5 to 60% by volume of nitrogen (N ₂ ) gas, and the rest Prepares a mixed gas composed of hydrogen (H ₂ ) gas and introduces it into the reaction chamber, and forms a bonding layer at 950 to 1100 ° C. and 5 to 30 kPa in the chamber.

Next, the oxygen-containing compound layer 4 is formed. At this time, as the reaction gas composition of the TiCNO composition oxygen-containing compound, titanium chloride (TiCl ₄ ) gas is 1.2 to 2.5% by volume, carbon dioxide (CO ₂ ) gas is 1.0 to 3.0% by volume, methane A mixed gas consisting of 1.0 to 10% by volume of (CH ₄ ) gas, 5 to 60% by volume of nitrogen (N ₂ ) gas, and the remaining hydrogen (H ₂ ) gas was prepared and introduced into the reaction chamber, The inside of a chamber shall be 950-1100 degreeC and 5-20 kPa. Alternatively, as the reaction gas composition of the TiCO composition oxygen-containing compound, titanium chloride (TiCl ₄ ) gas is 1.2 to 2.5% by volume, carbon dioxide (CO ₂ ) gas is 1.0 to 3.0% by volume, methane ( A mixed gas composed of 1.0 to 10% by volume of CH ₄ ) gas and the remaining hydrogen (H ₂ ) gas is prepared and introduced into the reaction chamber, and the inside of the chamber is set to 950 to 1100 ° C. and 5 to 20 kPa.

Further, as a reaction gas composition of the TiNO composition oxygen-containing compound, titanium chloride (TiCl ₄ ) gas is 1.2 to 2.5% by volume, carbon dioxide (CO ₂ ) gas is 1.0 to 3.0% by volume, nitrogen ( A mixed gas composed of 5 to 60% by volume of N ₂ ) gas and the remaining hydrogen (H ₂ ) gas is prepared and introduced into the reaction chamber, and the inside of the chamber is set to 950 to 1100 ° C. and 5 to 20 kPa.

Here, according to this embodiment, the total flow rate V TiCl _{4 + CO 2} (L / min) of titanium chloride (TiCl ₄ ) and carbon dioxide (CO ₂ ) is used as the reaction gas when forming the oxygen-containing compound layer 4 in the CVD furnace. When the ratio V _{TiCl 4 + CO 2} / Va divided by the effective volume Va (L) is 0.015 to 0.035, the aspect ratio of the oxygen-containing compound in the rake face cross-sectional direction can be controlled in the range of 8 to 20. Here, when V _{TiCl 4 + CO 2} / Va is 0.015 or less, the aspect ratio of the oxygen-containing compound becomes small. In addition, when V _{TiCl4 + CO2} / Va is 0.035 or more, the aspect ratio of the oxygen-containing compound is increased.

Further, in the reaction gas when the oxygen-containing compound layer 4 is formed, the ratio CO ₂ / TiCl ₄ (flow rate ratio) obtained by dividing the flow rate of carbon dioxide (CO ₂ ) by the flow rate of titanium chloride (TiCl ₄ ) is 0.7-2. When it is in the range of 0.0, the crystal height of the oxide-containing compound can be easily controlled in the range of 1.0 to 10 μm. When CO ₂ / TiCl ₄ (flow rate ratio) is 0.7 or less, the crystal height of the oxygen-containing compound tends to be small because there is not enough oxygen relative to titanium chloride. When CO ₂ / TiCl ₄ (flow rate ratio) was 2.0 or more, the crystal height of the oxygen-containing compound tended to be very large. Further, the ratio V _{TiCl 4 + CO 2} / Va (L / min) is in the range of 0.015 to 0.035, CO ₂ / TiCl ₄ (flow rate ratio) is in the range of 0.7 to 2.0, and V _{TiCl 4 + CO 2} When / Va is in the range of 0.015 to 0.035, the presence of dititanium trioxide (Ti ₂ O ₃ ) was confirmed. The presence of Ti ₂ O ₃ was determined by identification after measuring an arbitrary portion by X-ray diffraction.

Next, in the reaction gas of the film in which the oxygen-containing compound that is an acicular crystal is embedded, as the reaction gas composition of the TiCN composition oxygen-containing compound, 0.5 to 1.2% by volume of titanium chloride (TiCl ₄ ) gas, methane (CH ₄ ) A mixed gas consisting of 1.0 to 10% by volume of 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. Is 950 to 1100 ° C. and 6 kPa.

Or, titanium chloride (TiCl ₄₎ gas as a reaction gas composition of TiC composition oxygenate 0.5-1.2 vol%, 1.0 to 10 vol% methane (CH ₄₎ gas, the remaining hydrogen (H ₂ ) A mixed gas composed of gas is adjusted and introduced into the reaction chamber, and the inside of the chamber is set to 950 to 1100 ° C. and 6 kPa.

Further, as a reaction gas composition of the TiN composition oxygen-containing compound, titanium chloride (TiCl ₄ ) gas is 0.5 to 1.2% by volume, nitrogen (N ₂ ) gas is 5 to 60% by volume, and the remainder is hydrogen (H ₂ ). A mixed gas composed of gas is adjusted and introduced into the reaction chamber, and the inside of the chamber is set to 950 to 1100 ° C. and 6 kPa. Here, according to this embodiment, in order to fill the gaps between the needle crystals, the source gas adsorbed from the gas phase to the film formation surface does not immediately crystallize on the surface, and surface diffusion is sufficiently possible. Increased surface diffusion time. Specifically, by reducing the component ratio of the raw material gas as much as possible and reducing the component ratio of the raw material gas, the frequency of the raw material gas component adsorbed on the surface collides with other raw material gases to reduce the surface of the raw material gas component Can diffuse and enter so as to be embedded in gaps or recesses between needle crystals.

  Further, in some cases, the upper layer portion can be improved in wear resistance by forming an α alumina layer, titanium nitride, zirconium nitride or the like. Then, if desired, at least the cutting edge portion on the surface of the formed coating layer 3 is polished. By this polishing process, the residual stress remaining in the coating layer 3 is released, and the tool is further excellent in fracture resistance.

  In addition, although the said method demonstrated CVD method, the tool 1 of this invention is producible also with the manufacturing method using other film-forming methods (physical vapor deposition method, plasma CVD, etc.).

  A metal cobalt (Co) powder with an average particle diameter of 1.2 μm is added to and mixed with tungsten carbide (WC) powder with an average particle diameter of 1.5 μm at a ratio of 6% by mass, and the cutting tool shape ( After forming into CNMA120408), a binder removal treatment was performed, and a cemented carbide was produced by firing at 1500 ° C. for 1 hour in a vacuum of 0.01 Pa. Further, the prepared cemented carbide was subjected to blade edge processing (Honing R) processing from the rake face by brushing.

  Next, various hard coating layers were formed on the cemented carbide by chemical vapor deposition (CVD), and sample No. 1 to 12 surface-coated cutting tools were produced. Each sample No. Table 2 shows the film configuration for each. The deposition conditions for each layer in Table 2 are shown in Table 1.

Further, after coating the hard coating layer, the surface of the sample was polished to adjust the layer thickness of the outermost layer to the values shown in Table 2, and the surface roughness was adjusted to the values in Table 2.

The obtained tool was polished using a transmission electron microscope (TEM) so that the coating layer described in Table 2 could be observed, and the microstructural state viewed from the cross-sectional direction of each layer was observed. The crystal height was measured by observing this state. Also, the elemental mapping using a transmission electron microscope (TEM) was used to observe the microscopic element distribution state as seen from the direction parallel to the base of the needle-like part by polishing, and the long-axis and short-axis states of the needle-like crystal part Was observed. In addition, the presence of Ti ₂ O ₃ crystals was measured by X-ray diffraction (XRD). The surface roughness was measured at three locations in the vicinity of the cutting edge with a stylus type surface roughness meter, and the average value was obtained. The results are shown in Table 2.

  Then, using this tool, a light interrupted cutting test and a strong interrupted cutting test were performed under the following conditions to evaluate the wear resistance and fracture resistance.

(Light interrupted cutting conditions)
Work Material: FC300 Single Grooved Cylindrical Tool Shape: CNMA120408
Cutting speed: 350 m / min Feeding speed: 0.3 mm / rev
Cutting depth: 1.5mm
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 (strongly interrupted cutting conditions)
Work Material: FCD700 4 Grooved Cylindrical Tool Shape: CNMA120408
Cutting speed: 450 m / min Feeding speed: 0.45 mm / rev
Cutting depth: 2mm
Cutting fluid: Mixture of 15% emulsion + 85% water Evaluation item: Number of impacts leading to defects
Table 3 shows the results of observation of the state of the cutting edge with a microscope at the time of impact of 1000 times.

  From Tables 1 to 3, Sample No. in which either the non-oxide phase or the acicular titanium compound phase does not exist or the acicular crystals are not appropriate. In 9-12, chipping occurred and the chipping resistance was poor.

  On the other hand, according to the present invention, in samples 1 to 8 in which a layer in which a non-oxide titanium compound phase is embedded in an acicular titanium compound phase containing oxygen is present, it has a long life both in continuous cutting and in intermittent cutting, Both the chipping resistance and chipping resistance had excellent cutting performance.

It is a principal part expanded sectional view (drawing substitute photograph) which showed the layer structure of the hard coating layer in an example of embodiment of the surface covering cutting tool of this invention. It is a principal part expanded sectional view (drawing substitute photograph) of the state which formed even the titanium compound phase containing oxygen as a hard coating layer on the base-material surface in the surface coating cutting tool of this invention. FIG. 3 is a view in the direction of arrow A in FIG. 2 (drawing substitute photograph).

Explanation of symbols

1: Tool (surface coated cutting tool)
2: Base 3: Hard coating layer 4: Oxygen-containing titanium compound phase 5: Non-oxide phase 6: Acicular crystal particles 7: Complex area of oxygen-containing titanium compound phase and non-oxide phase 8: Acicular Particle layer 9: Upper layer 10: Acicular particles of titanium compound containing oxygen h: Average crystal height (μm) of the titanium compound phase containing oxygen viewed from the cross-sectional direction
w1: minor axis width (μm) of a titanium compound phase containing oxygen in a cross-sectional field parallel to the substrate
w2: long axis width (μm) of titanium compound phase containing oxygen in a cross-sectional field parallel to the substrate

Claims (6)

A surface-coated cutting tool in which a hard coating layer composed of multiple layers is formed on the surface of a substrate,
The hard coating layer is a non-oxidized compound comprising a titanium compound phase containing oxygen and at least one compound selected from the group consisting of carbides, nitrides, and carbonitrides of group 4 elements adjacent to the titanium compound phase containing oxygen. Including the physical phase,
The titanium compound containing oxygen is composed of acicular crystal particles having an aspect ratio in the range of 8 to 100 in a cross-sectional view parallel to the substrate surface,
A surface-coated cutting tool, wherein a complex region between the titanium compound phase containing oxygen and the non-oxide phase exists in a region near the interface between the titanium compound phase containing oxygen and the non-oxide phase. 2. The surface-coated cutting tool according to claim 1, wherein the crystal grains of the titanium compound containing oxygen have an average crystal height of 1 to 10 μm in a cross-sectional view perpendicular to the substrate surface. The surface-coated cutting tool according to claim 1, wherein the titanium compound containing oxygen contains Ti ₂ O ₃ , and the non-oxide phase is made of at least one of TiCN and TiN. The crystal grains of the titanium compound containing oxygen have an average major axis width of 1 to 4 μm and an average minor axis width of 0.03 to 0.5 μm in a cross-sectional view parallel to the substrate surface. Item 4. The surface-coated cutting tool according to any one of Items 1 to 3. The non-oxide phase is composed of a titanium nitride layer as a surface layer of the hard coating layer, and the titanium compound containing oxygen is exposed and complexed with the titanium compound containing oxygen on the intersection of the upper surface and the side surface of the substrate. The surface-coated cutting tool according to any one of claims 1 to 4, wherein the titanium nitride layer is polished so that a part of the titanium nitride layer remains and is exposed. The surface-coated cutting tool according to claim 1, wherein a maximum height Rz of the surface of the hard coating layer is 0.5 to 1.5 μm.

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