JPS6245196B2 - - Google Patents

Description

[Detailed description of the invention]

This invention has particularly excellent toughness and wear resistance, high hardness, and excellent heat resistance and high-temperature strength, and is applicable to high-speed steels and Ni-based or Co-based superalloys that require these properties. The present invention relates to a boron nitride-based ultra-high-pressure sintered material suitable for use as a cutting tool for workpieces such as steel, etc., and as a wear-resistant tool for bearings, wire drawing dies, and the like. In recent years, compared to tungsten carbide-based sintered materials,
It has been proposed to use cubic boron nitride-based ultra-high pressure sintered materials (hereinafter referred to as CBN-based sintered materials), which have extremely excellent wear resistance, as cutting tools and wear-resistant tools. This CBN-based sintered material forms a dispersed phase
CBN particles can be roughly divided into two types depending on the binder phase, one of which is iron group metal or
One is composed of a metal whose main component is Al, and the other is a binder phase composed of a ceramic compound whose main component is titanium nitride, titanium carbide, aluminum nitride, or aluminum oxide. However, in the former, as the binder phase is metal as mentioned above, it easily softens at high temperatures, and therefore, when used as a cutting tool, for example, it must be used under harsh cutting conditions that generate a large amount of heat. However, it cannot be expected to exhibit sufficient cutting performance due to insufficient wear resistance, and can only be used under conditions where there is little heat generation, that is, under low load conditions. In addition, in the latter case, since the binder phase is composed of a ceramic compound as mentioned above, it has excellent heat resistance and wear resistance, but on the other hand, lack of toughness cannot be avoided. For example, chipping and chipping are likely to occur under cutting conditions in which a large impact force is applied to the cutting edge, such as when milling high-speed steel. In addition, in order to solve the respective problems of the above two types of conventional CBN-based sintered materials, we have developed CBN with a binder phase composed of a metal and a ceramic compound.
CBN-based sintered materials have also been proposed, but these CBN-based sintered materials do not exhibit sufficiently satisfactory toughness, and similarly cannot be cut under cutting conditions where large impact forces are applied to the cutting edge, such as when milling high-speed steel. When used as a tool, the cutting edge is likely to be damaged. This is due to the CBN in the above CBN-based sintered material.
This was revealed through detailed observation of the boundary between the particles and the binder phase (metal + ceramic compound) using a scanning electron microscope. Small unbonded parts (voids) are formed at the boundary due to the binder phase not wrapping around the binder phase sufficiently, and the adhesion between the CBN particles and the binder phase is affected by the constituent components of the binder phase. Although it differs depending on the case, it is particularly low in the case of carbide-based ceramics, and this is thought to be due to the formation of regions with weak bond strength between the CBN particles and the binder phase. Furthermore, with conventional CBN-based sintered materials such as those mentioned above, this is not possible under conditions where thermal shock is likely to occur, such as during wet milling of high-speed steel. Then,
On the other hand, when used under conditions where the cutting edge is exposed to repeated cycles in which the cutting edge separates from the workpiece and is cooled down to a low temperature, if there is a large difference in the coefficient of thermal expansion between the CBN particles and the binder phase, thermal expansion and contraction may occur. Due to the large difference in the bonding phase, thermal cracks are likely to occur, and this large difference in expansion and contraction also reduces the strength of the binder phase itself. Therefore, from the above-mentioned viewpoint, the present inventors conducted research to obtain a CBN-based sintered material with particularly excellent toughness and wear resistance, as well as excellent thermal shock resistance. The sintered material is made of one or more borides of Ti, Hf, Zr, and Mo (hereinafter referred to as borides of each element).
_TiB2 , _HfB2 , _ZrB2 , and MoB): 5~
40% by weight, one or more carbides of Ti, Hf, Zr, Mo, and W (hereinafter, the carbides of each element are referred to as TiC, HfC, ZrC, Mo ₂ C, and WC): 5 to Contains 35% by weight and the rest is CBN
It has a composition consisting of (cubic boron nitride) and unavoidable impurities, and CBN occupies 40 to 90% by volume, and the boride has a CBN particle size of 0.1 to 2 μm.
Assuming that the CBN particles surrounding the dispersed phase have a structure with an average layer thickness of and the above boride is added in advance during raw material preparation.
The surface of CBN particles is strongly and densely coated using methods such as chemical vapor deposition (CVD), plasma chemical vapor deposition (PCVD), and physical vapor deposition (PVD). There are no unbonded parts (voids) at the interface between the two, which not only results in high toughness, but also high wear resistance due to the composition of each of the above components,
Moreover, since the above-mentioned boride has a coefficient of thermal expansion intermediate between that of CBN particles and carbide, it acts as a buffer against severe thermal shock, making it extremely difficult for thermal cracks to occur. One or two of Al, Zr, and Y are added to the sintered material.
When 5 to 15% by weight of oxides of various elements or more (hereinafter, oxides of each element are referred to as Al ₂ O ₃ , ZrO ₂ , and Y ₂ O ₃ ) are contained, chemical stability against high temperatures in practical use is improved. Furthermore, when one or more of Ni, Al, Co, and Si are contained in the range of 0.5 to 15% by weight, these components have a deoxidizing effect and a bonding effect. Because it has the effect of strengthening the bonding force between homologs, the material becomes more dense,
In addition, a portion of CBN in these CBN-based sintered materials is added to wurtzite within a range that does not exceed CBN, that is, within a range that satisfies 0.05<wurtzite boron nitride (volume%)/CBN (volume%)<1. type boron nitride (below
They found that replacing the material with WBN (denoted by WBN) further increases the toughness of the material. This invention was made based on the above knowledge, and the component composition, CBN and WBN are as follows.
The reason why the volume ratio and the average layer thickness of the boride surrounding layer are limited as described above will be explained. A Component composition (a) Borides TiB ₂ , HfB ₂ , ZrB ₂ and MoB include:
By strongly bonding with the CBN particles and the carbide that forms the binder phase, and coating the surface of the CBN particles during raw material preparation, there is no unbonded part at the boundary that can cause toughness deterioration. In addition to significantly improving the toughness of the material, these borides have an intermediate coefficient of thermal expansion between the CBN particles and the binder phase, which has the effect of suppressing the occurrence of thermal cracks in the material. If the content is less than 5% by weight, the surface of the CBN particles cannot be completely surrounded by a predetermined layer thickness, so the desired effect cannot be obtained; on the other hand, if the content exceeds 40% by weight, Since the abrasion resistance will deteriorate if
It was determined that (b) Carbides TiC, HfC, ZrC, Mo ₂ C, and WC have the effect of imparting wear resistance to materials, but if their content is less than 5% by weight, the desired excellent wear resistance cannot be achieved. Unable to secure
On the other hand, if the content exceeds 35% by weight, the toughness of the material deteriorates, so the content was set at 5 to 35% by weight. (c) Oxides Al ₂ O ₃ , ZrO ₂ , and Y ₂ O ₃ have the effect of chemically stabilizing materials against high temperatures in practical use, so they are particularly effective in high-temperature corrosion resistance and high-temperature oxidation resistance. It is included as necessary when required, but if the content is less than 5% by weight, the desired effect cannot be obtained, whereas 15% by weight
If the content exceeds 5 to 15%, the toughness of the material will deteriorate.
It was determined as weight%. (d) Metal components Ni, Al, Co, and Si have the effect of deoxidizing and strengthening the bonding force between bonding phases, and are necessary because the inclusion of these metal components makes the material even more dense. However, if the content is less than 0.5% by weight, the desired effect will not be obtained, while if the content exceeds 15% by weight, the wear resistance will deteriorate. Its content is 0.5~
It was set at 15% by weight. B Volume ratio of CBN If the ratio of CBN to the binder phase is less than 40% by volume, the ratio of relatively hard CBN is too small to ensure the desired wear resistance, whereas if the ratio of CBN is 90% by volume. If the volume ratio exceeds 40%, the ratio of the binder phase becomes relatively too small, resulting in a decrease in toughness.
It was set at ~90 capacity%. C Substitution ratio of WBN Since WBN has the effect of further improving the toughness of the material, when particularly high toughness is required, CBN may be included in a partially substituted form as necessary. In other words, if WBN (volume %)/CBN (volume %) is less than 0.05, the desired high toughness cannot be secured, while if the substitution ratio exceeds 1, that is, relatively compared to CBN.
If there is more WBN, the hardness of the material will decrease and the wear resistance will deteriorate. Therefore, when replacing part of CBN with WBN, 0.05<WBN/CBN<1. conditions must be met. D Average layer thickness of boride If the average layer thickness is less than 0.1μm, CBN particles,
Alternatively, it is not possible to obtain sufficient bonding strength between CBN particles and WBN particles and the binder phase, and it is also not possible to satisfactorily alleviate the difference in thermal expansion between the two, and on the other hand, the average layer thickness is 2
If it exceeds 25% by weight, the amount of boride will be too large and the wear resistance of the material will deteriorate, so the average layer thickness should be reduced to 0.1 to 2μm.
It was determined as m. The ultra-high pressure sintered material of this invention first has the following characteristics:
One or more of TiB ₂ , HfB ₂ , ZrB ₂ , and MoB is added to the surface of CBN powder and, if necessary, WBN powder at a concentration of 0.1 using methods such as CVD, PCVD, and PVD. Coated with an average layer thickness of ~2 μm, and optionally further coated with TiC,
Boride-coated CBN powder and WBN powder prepared in this manner, and boride- and carbide-coated CBN powder coated with one or more of HfC, ZrC, Mo ₂ C, and WC by multilayer vapor deposition. and
WBN powder, as well as TiC powder, HfC _powder , ZrC powder, _Mo2C powder, WC powder, _Al2O3 powder, _ZrO2 powder, _Y2O3 powder, Ni powder, Al powder, Co powder, _Si powder, and An alloy powder of two or more of these metals is prepared as a raw material powder, appropriately selected from these raw material powders and blended into a predetermined composition, and after this blended powder is mixed under normal conditions, it is processed into a powder state or molded. In this condition, if necessary, the container is placed together with a cemented carbide plate, etc., heated to a temperature of 800 to 1200°C, vacuum degassed, and sealed. It is attached to an ultra-high pressure and high temperature generator as described in Publication No. 36-23463, and the pressure and temperature are increased to a pressure of 40~
70Kb, Temperature: Can be produced by a basic process consisting of holding at a pressure and temperature in the range of 1200-1600°C for several minutes to several tens of minutes, then cooling and finally releasing the pressure. . Next, the ultra-high pressure sintered material of the present invention will be specifically explained using Examples. Example 1 As raw material powder, known CVD method or PCVD
Coated CBN powder and coated WBN powder each prepared in the state shown in Table 1 using the method, the above various carbide powders having an average particle size of 2 μm, Table 2
The above-mentioned various oxide powders having μm, and the same 2 μm
Prepare the above various metal powders with a diameter of μm, blend these raw powders into the compositions shown in Table 1, wet mix these blended powders in a ball mill for 2 to 10 hours, and then remove the mixed powders. Diameter: 12mm
Packed into a φ mild steel container, vacuum degassed and sealed at a temperature of 800℃, then installed in a known ultra-high pressure and high temperature generator, pressure: 50-60Kb, temperature: 1300-1500
°C, holding time: 15 to 20 minutes, the basic process consists of finally cooling and gradually lowering the pressure, resulting in a final composition that is essentially the same as the blended composition. Ultra-high pressure sintered materials 1 to 22 of the present invention were manufactured. Next, regarding the ultra-high pressure sintered materials 1 to 22 of the present invention obtained as a result, work material: die steel (SKD-
11. Hardness: H _R C62), Cutting speed: 100m/min, Feed: 0.1mm/rev., Depth of cut: 0.5mm, Cutting oil: No wear on the flank surface of the cutting edge.
Cutting test to measure life time up to 0.2mm

【table】

【table】

[Table] (referred to as cutting test A), work material: die steel (SKD-61, hardness: H _R C50), cutting speed: 120 m/
min, depth of cut: 0.5mm, feed: 0.05, 0.1, 0.15,
During milling under the conditions of 0.2, 0.3, and 0.4 mm/rev., cutting time for each feed: 5 minutes, and cutting oil: with, the feed rate at the time when chipping due to thermal cracking was observed on the cutting edge. A cutting test (referred to as cutting test B) was conducted for each test.
The cutting test results are shown in Table 2. Table 2 shows commercially available ultra-high pressure sintered materials (conventionally referred to as ultra-high pressure sintered materials 1) whose dispersed phase is composed of CBN and whose binder phase is TiCN, and those whose binder phase is composed of Co. The cutting test results of a commercially available ultra-high pressure sintered material (referred to as conventional ultra-high pressure sintered material 2) under the same conditions are also shown. As shown in Table 2, the ultra-high pressure sintered materials 1 to 22 of the present invention all have excellent wear resistance and toughness, so they are superior to conventional materials that are inferior in either of these properties. High pressure sintered material 1, 2
It is clear that the material exhibited superior cutting performance in both cutting tests A and B. Example 2 The coated CBN powder and the coated WBN powder shown in Table 3 were used, and the mixed powder or green compact was prepared with a diameter having a composition consisting of Co: 12% by weight, WC and unavoidable impurities: the remainder. :
11.5mmφ cemented carbide plate and outer diameter: 12mm
It was packed in a Mo container with a diameter of φ, and the container was heated to a temperature of 800° C. in H ₂ gas for cleaning treatment before vacuum degassing treatment under substantially the same conditions as in Example 1. Ultra-high pressure sintered material 23 of the present invention having the same final component composition as shown in Table 3
~28 were produced respectively. The ultra-high pressure sintered materials 23 to 28 of the present invention were subjected to a cutting test under the cutting conditions A and B, and the results are shown in Table 4 along with the Vickers hardness. As shown in Table 4, in the ultra-high pressure sintered materials 23 to 28 of the present invention, similar to the case of Example 1, the cutting ability was even better than that of the conventional ultra-high pressure sintered materials.

【table】

【table】 It is clear that it exhibits cutting performance.

[Table] As mentioned above, the ultra-high pressure sintered material of this invention is
It has excellent wear resistance and toughness, as well as high hardness, excellent heat resistance, and high temperature strength, so it can be used not only for cutting tools that require these properties, but also for bearings, wire drawing dies, etc. It also exhibits excellent performance when used as a wear-resistant tool.

Claims (1)

[Claims] 1 One or more borides of Ti, Hf, Zr, and Mo: 5 to 40% by weight, Ti, Hf, Zr, Mo,
and one or more carbides of W: 5 to 35
% by weight, with the remainder consisting of cubic boron nitride and unavoidable impurities, and the cubic boron nitride accounts for 40 to 90% by volume, and the boride contains cubic boron nitride in a proportion of 0.1 to 90% by volume. A high-toughness boron nitride-based ultra-high pressure sintered material for cutting and wear-resistant tools, characterized by having an enclosed structure with an average layer thickness of 2 μm. 2 One or more borides of Ti, Hf, Zr, and Mo: 5 to 40% by weight, Ti, Hf, Zr, Mo,
and one or more carbides of W: 5 to 35
% by weight and further contains 1 of Al, Zr, and Y.
Species or two or more oxides: Contains 5 to 15% by weight, with the remainder consisting of cubic boron nitride and unavoidable impurities, and cubic boron nitride as a volume percentage.
High-toughness boron nitride-based ultra-high-pressure sintering for cutting and wear-resistant tools, characterized in that the boride occupies 40 to 90% and has a structure in which cubic boron nitride is surrounded by an average layer thickness of 0.1 to 2 μm. material. 3 One or more borides of Ti, Hf, Zr, and Mo: 5 to 40% by weight, Ti, Hf, Zr, Mo,
and one or more carbides of W: 5 to 35
% by weight and further contains Ni, Al, Co, and
Contains one or more types of Si: 0.5 to 15% by weight, with the remainder consisting of cubic boron nitride and unavoidable impurities, and cubic boron nitride in a volume percentage.
High-toughness boron nitride-based ultra-high-pressure sintering for cutting and wear-resistant tools, characterized in that the boride occupies 40 to 90% and has a structure in which cubic boron nitride is surrounded by an average layer thickness of 0.1 to 2 μm. material. 4 One or more borides of Ti, Hf, Zr, and Mo: 5 to 40% by weight, Ti, Hf, Zr, Mo,
and one or more carbides of W: 5 to 35
% by weight and further contains 1 of Al, Zr, and Y.
Species or two or more oxides: 5 to 15% by weight;
One or more of Ni, Al, Co, and Si:
0.5 to 15% by weight, with the remainder consisting of cubic boron nitride and unavoidable impurities, and cubic boron nitride occupies 40 to 90% by volume,
A high-toughness boron nitride-based ultra-high pressure sintered material for cutting and wear-resistant tools, characterized in that the boride has a structure in which cubic boron nitride is surrounded by an average layer thickness of 0.1 to 2 μm. 5 One or more borides of Ti, Hf, Zr, and Mo: 5 to 40% by weight, Ti, Hf, Zr, Mo,
and one or more carbides of W: 5 to 35
% by weight, with the remainder consisting of cubic boron nitride, wurtzite boron nitride, and unavoidable impurities, and cubic boron nitride and wurtzite boron nitride occupy 40 to 90% by volume. , 0.05<wurtzite boron nitride (volume %)/cubic boron nitride (volume %)<1, and further, the boride contains cubic boron nitride and wurtzite boron nitride in an average layer of 0.1 to 2 μm. A high-toughness boron nitride-based ultra-high pressure sintered material for cutting and wear-resistant tools, characterized by having a thick and enclosed structure. 6 One or more borides of Ti, Hf, Zr, and Mo: 5 to 40% by weight, Ti, Hf, Zr, Mo,
and one or more carbides of W: 5 to 35
% by weight and further contains 1 of Al, Zr, and Y.
Species or two or more oxides: Contains 5 to 15% by weight, with the remainder consisting of cubic boron nitride, wurtzite boron nitride, and unavoidable impurities, and contains cubic boron nitride and wurtzite boron nitride. Boron in volume percentage
40 to 90%, and satisfies 0.05<wurtzite boron nitride (volume %)/cubic boron nitride (volume %)<1, and furthermore, the boride contains cubic boron nitride and wurtzite boron nitride. 1. A high-toughness boron nitride-based ultra-high pressure sintered material for cutting and wear-resistant tools, characterized by having a structure in which the nitride is surrounded by an average layer thickness of 0.1 to 2 μm. 7 One or more borides of Ti, Hf, Zr, and Mo: 5 to 40% by weight, Ti, Hf, Zr, Mo,
and one or more carbides of W: 5 to 35
% by weight and further contains Ni, Al, Co, and Si
One or more of: 0.5 to 15% by weight, with the remainder consisting of cubic boron nitride, wurtzite boron nitride, and inevitable impurities, and cubic boron nitride and wurtzite boron nitride. is the volume percentage
40 to 90%, and satisfies 0.05<wurtzite boron nitride (volume %)/cubic boron nitride (volume %)<1, and furthermore, the boride contains cubic boron nitride and wurtzite boron nitride. 1. A high-toughness boron nitride-based ultra-high pressure sintered material for cutting and wear-resistant tools, characterized by having a structure in which the nitride is surrounded by an average layer thickness of 0.1 to 2 μm. 8 One or more borides of Ti, Hf, Zr, and Mo: 5 to 40% by weight, Ti, Hf, Zr, Mo,
and one or more carbides of W: 5 to 35
% by weight and further contains 1 of Al, Zr, and Y.
Species or two or more oxides: 5 to 15% by weight;
One or more of Ni, Al, Co, and Si:
0.5 to 15% by weight, with the remainder consisting of cubic boron nitride, wurtzite boron nitride, and unavoidable impurities, and cubic boron nitride and wurtzite boron nitride account for 40 to 90% by volume. and satisfies 0.05<wurtzite boron nitride (volume %)/cubic boron nitride (volume %)<1, and furthermore, the boride has a particle size of 0.1 to 2 μm of cubic boron nitride and wurtzite boron nitride. A high-toughness boron nitride-based ultra-high pressure sintered material for cutting and wear-resistant tools, characterized by having an enclosed structure with an average layer thickness of .