JP3064350B2 - High wear resistant composite sintered body - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an oxide-based composite sintered body having excellent wear resistance, welding resistance, lubricity, strength, toughness and surface accuracy. The present invention relates to a high wear resistant composite sintered body suitable for a cutting tool represented by a turning tool, a milling tool or a wear resistant tool represented by a slitter.

The (prior art) conventional oxide composite sintered body is used as a cutting tool or wear tool, Al ₂ O ₃ -MgO based sintered body and Zr
O ₂ -Y ₂ it can be roughly classified into O ₃ sintered body. Among them, the former has excellent wear resistance but has extremely low toughness and is susceptible to fracture. The latter has the effect of preventing crack propagation due to volume expansion accompanying phase transformation, and has a high fracture toughness value and high strength. However, there is a problem that the hardness is low, and particularly, the hardness is remarkably reduced at high temperature and the wear resistance is inferior. Many proposals have been made to solve these problems,
Of these, a representative sintered body mainly composed of three components of Al ₂ O ₃ —ZrO ₂ —Cr ₂ O ₃ is disclosed in JP-A-1-290557.

(Problems to be Solved by the Invention) JP-A-1-290557 discloses that 60-95% by weight of ZrO ₂ containing 1-5 mol% of a stabilizer and 1-20% by weight of Cr ₂ O ₃ are solidified. A composite sintered body composed of a soluble Al ₂ O ₃ solid solution is disclosed.

Although the composite sintered body disclosed in this publication is an excellent sintered body that has achieved high strength and high toughness, it has poor welding resistance at high temperatures, poor wear resistance, low lubricity, and There is a problem that the use as a wear-resistant tool is limited due to poor surface accuracy, and that it is difficult to put it into practical use as a cutting tool.

The present invention has solved the above-mentioned problems. Specifically, the present invention adjusts aluminum oxide, chromium oxide, and zirconium oxide containing a stabilizer in a well-balanced manner, and further forms a metal phase and / or chromium carbide. It is an object of the present invention to provide a highly wear-resistant composite sintered body which is excellent as a cutting tool or a wear-resistant tool which has succeeded in exerting the respective characteristics to the maximum by containing the same.

(Means for Solving the Problems) The present inventors perform cutting of a workpiece such as steel or casting, or plastic working or cutting of a workpiece such as a SUS material, a Cu alloy, or an Al alloy. In such cases, the work material is welded or adhered to the work surface of the tool, and this causes rapid wear of the work surface of the tool, leading to severe roughness of the work surface in the work material. First, the sintered body containing chromium oxide is difficult to be welded to the metal to be processed, has a low coefficient of friction, and when the polishing is performed, the processed surface of the sintered body is That the accuracy of
As a result, it has been found that when used as a tool, the adhesion of the workpiece is significantly reduced.

Second, wear resistance that can be used as a severe cutting tool,
In order to maintain toughness and maximize the effect of chromium oxide described above, aluminum oxide, which is easily dissolved in chromium oxide and is mainly effective in improving wear resistance, and is mainly effective in improving toughness It has been found that this can be achieved by adjusting the composition of the three components of zirconium oxide having certain properties and chromium oxide.

The present invention has been completed based on the first and second findings.

That is, the high wear resistant composite sintered body of the present invention is Cr, Co,
Ni, Fe and at least one type of metal phase among these alloys is 10% by weight or less, the balance is a composite sintered body consisting of a metal oxide phase and unavoidable impurities, the metal oxide phase,
Zirconium oxide containing 1 to 5 mol% of at least one of MgO, CaO, rare earth oxides and their mutual solid solutions
It is characterized by comprising 10 to 85% by weight, 10 to 72% by weight of chromium oxide and 5 to 80% by weight of aluminum oxide.

Further, the high wear-resistant composite sintered body of the present invention is a composite sintered body composed of 30% by weight or less of chromium carbide and a balance of a metal oxide phase and unavoidable impurities. MgO,
Zirconium oxide containing 10 to 5 mol% of at least one of CaO, rare earth oxides and mutual solid solutions thereof
It is characterized by comprising 85% by weight, 10 to 72% by weight of chromium oxide and 5 to 80% by weight of aluminum oxide.

Further, the high wear-resistant composite sintered body of the present invention includes Cr, Co, N
A composite sintered body composed of at least one metal phase of i, Fe and their mutual alloys of 10% by weight or less, chromium carbide of 30% by weight or less, and a balance of a metal oxide phase and unavoidable impurities. The metal oxide phase contains 10 to 85% by weight of zirconium oxide containing 1 to 5 mol% of at least one of MgO, CaO, rare earth oxides and their mutual solid solution, and chromium oxide.
It is characterized by comprising 10 to 72% by weight and 5 to 80% by weight of aluminum oxide.

The zirconium oxide in the high wear-resistant composite sintered body of the present invention is preferable if one part or all of the zirconium oxide has a tetragonal crystal structure, because a further high-toughness sintered body can be obtained. Are monoclinic and tetragonal, or all of tetragonal, or tetragonal and cubic, or monoclinic, tetragonal and cubic. The stabilizer contained in the zirconium oxide is, specifically, MgO, CaO, or S
It is composed of at least one of rare earth oxides composed of c, Y and lanthanoid oxides and their mutual solid solutions.

When the amount of the stabilizing agent in the zirconium oxide is less than 1 mol%, the amount of the monoclinic zirconium oxide in the sintered body increases, and conversely, when the amount of the stabilizing agent exceeds 5 mol%, the sintering increases. Increasing the amount of cubic zirconium oxide in the compact results in a decrease in fracture resistance as a cutting tool, strength and wear resistance as a wear-resistant tool. For this purpose, the stabilizer in zirconium oxide is added in an amount of 1 to 5 mol%.
It is defined. If the amount of zirconium oxide containing this stabilizer is less than 10% by weight of the entire sintered body, the effect of improving the toughness due to the phase transformation of zirconium oxide from tetragonal to monoclinic is small, and the strength is significantly reduced. ,vice versa
If the content exceeds 85% by weight, the contents of aluminum oxide and chromium oxide are relatively reduced, resulting in inferior wear resistance, lubricity and welding resistance. For this reason, zirconium oxide containing a stabilizer is 10 to 85% of the entire sintered body.
%, Preferably 10 to 70% by weight.

In addition to the zirconium oxide containing the stabilizer, chromium oxide and aluminum oxide constituting the high wear-resistant composite sintered body of the present invention can be further improved if one part or all of them is a mutual solid solution. It is preferable because a sintered body having excellent wear resistance, lubricity, welding resistance and denseness can be obtained.
Specifically, a solid solution of chromium oxide and chromium oxide-aluminum oxide, only a solid solution of chromium oxide-aluminum oxide, or a solid solution of chromium oxide-aluminum oxide and aluminum oxide, or chromium oxide, aluminum oxide, and chromium oxide-aluminum oxide Consisting of a solid solution of

When the chromium oxide content is less than 10% by weight of the whole sintered body, the welding resistance and the lubricating property are reduced, and as a result, the chipping resistance and the abrasion resistance are reduced, and conversely, exceeding 72% by weight. As the content increases, the contents of zirconium oxide and aluminum oxide relatively decrease, resulting in a decrease in wear resistance and toughness.
For this purpose, the amount of chromium oxide in the sintered body is between 10 and 72% by weight, particularly preferably between 15 and 45% by weight.

On the other hand, if the aluminum oxide is less than 5% by weight of the whole sintered body, the wear resistance is remarkably reduced, and if it exceeds 80% by weight, the toughness and the welding resistance are reduced and the sintered body is liable to be broken. . For this purpose, the amount of aluminum oxide in the sintered body is from 5 to 80% by weight, particularly preferably from 5 to 60% by weight.

The highly wear-resistant composite sintered body of the present invention has different optimum effects depending on the content of the metal oxide phase of zirconium oxide, chromium oxide and aluminum oxide containing a stabilizer, and in particular, cutting tools. In particular, a sintered body containing 20 to 50% by weight of zirconium oxide, 15 to 40% by weight of chromium oxide, and 25 to 56% by weight of aluminum oxide containing a stabilizer is preferably used as a wear-resistant tool. In some cases, especially zirconium oxide containing a stabilizer 50-70
15% to 35% by weight of chromium oxide and aluminum oxide 9
A sintered body having a content of about 25% by weight is preferable.

The metal oxide phase in the high wear resistant composite sintered body of the present invention accounts for at least 10% by weight of the metal oxide phase and at least one metal phase among Cr, Co, Ni, Fe and their alloys. Is effective for increasing the strength and toughness of the sintered body, which is preferable for a wear-resistant tool in which strength and toughness are regarded as important. In this case, the metal phase is particularly preferably an alloy containing Cr and Ni, such as a Cr-Ni alloy, a Cr-Ni-Co alloy, a Cr-Ni-Fe alloy, and a Cr-Ni-Co-Fe alloy. Among them, alloys with a large Cr content have excellent heat resistance and oxidation resistance.

Also, replacing 30% by weight or less of the metal oxide phase with chromium carbon has the effect of increasing the strength and toughness of the sintered body.

Although the high wear-resistant composite sintered body of the present invention can be produced by applying the conventional powder metallurgy manufacturing method, a dense sintered body can be obtained by performing the following method. It is easy and preferable.

First, among the starting materials, the stabilizer and zirconium oxide may be used alone, but when the stabilizer is used in the form of a solid solution contained in zirconium oxide, there is an effect of increasing the toughness of the sintered body. This is preferred. In addition, aluminum oxide and chromium oxide as starting materials also form a solid solution at the time of sintering. Therefore, each may be used alone. However, if the solid solution treatment is performed beforehand, the suppression of grain growth at the time of sintering is suppressed. And the effect of increasing the strength and wear resistance of the sintered body is preferred.

When producing a sintered body by replacing the metal oxide phase with the metal phase, in addition to the metal powder for forming the metal phase,
A method using a metal oxide for forming a metal phase and its reducing equivalent carbon as a starting material, or, for example, CH 2
_4. Sintering in a carburizing atmosphere containing CO gas can also precipitate a metal phase from a metal oxide to form a metal phase. In particular, when a metal phase is formed, it is preferable to use an oxide of the metal as a starting material because the metal phase is finely and uniformly dispersed and the sintered body has excellent strength and wear resistance.

When a sintered body is prepared by replacing the metal oxide phase with chromium carbide, a mixture of Cr ₃ C ₂ , Cr ₇ C ₃ , Cr and carbon,
Alternatively, a mixture of chromium oxide and carbon can be used as a starting material. Among these, when a mixture of chromium oxide and carbon is used as a starting material, a kind of reaction sintering involving the formation reaction of chromium metal and the solid solution reaction of chromium oxide-aluminum oxide in addition to the formation reaction of chromium carbide is performed. This is preferable because it occurs.

When these starting materials are mixed, for example, it is preferable to use a stainless steel mixing vessel lined with polyurethane in a ball mill and pulverize in an organic solvent such as methanol, since mixing of impurities can be easily prevented.

When hot-press sintering the mixed powder obtained in this way, the mixed powder is filled in a carbon mold coated with boron nitride (hBN) powder, and the mixture is placed in N ₂ or an inert gas.
The reaction can be performed at a temperature of 1300 to 1500 ° C. and a pressure of about 200 kgf / cm ² .

In the case of normal pressure sintering, a molding binder is added to the mixed powder, and a molded body is formed by molding or hydrostatic molding at a pressure of, for example, 1 ton / cm ² or more, and the molding binder in the molded body is removed. Later, it can be performed at a temperature of 1400-1600 ° C.

Furthermore, when sintering is performed in an atmosphere of vacuum, gas decompression, or gas pressure, for example, in order to obtain a sintered body containing a metal phase or chromium carbide, it is necessary to use a non-oxidizing or carburizing atmosphere. In particular, about 0.1 to 3 Cr
In order to obtain a sintered body dispersed in weight%, it is easy to sinter a mixed powder of zirconium oxide, aluminum oxide and chromium oxide in a carbon mold by hot press sintering or by vacuum or pressure sintering in a carbon heater furnace. Can be obtained.

Such a sintered body obtained by, for example in Ar or N _2, 10
It is also preferable to perform hot isostatic pressing (HIP) at a pressure of 00 to 2000 atm and a temperature of 1200 to 1500 ° C. to improve the strength and wear resistance of the sintered body.

(Function) In the high wear resistant composite sintered body of the present invention, zirconium oxide containing a stabilizing agent is uniformly distributed in a phase of aluminum oxide and chromium oxide in which a part or the whole has become a solid solution. Form a dense sintered body, stabilized zirconium oxide in this sintered body mainly acts to increase the strength and toughness,
The phase of aluminum oxide and chromium oxide functions to enhance wear resistance, welding resistance, and lubricity.

Examples Commercially available Y-PSZ (ZrO ₂ containing 3 mol% of Y ₂ O ₃ having a primary particle diameter of 230 °) powder, Mg-PSZ (ZrO ₂ containing 3 mol% of MgO having the same particle diameter) powder, Y · Yb-PSZ (ZrO ₂ containing 2 mol% of Y ₂ O ₃ and 1 mol% of Yb ₂ O ₃ having the same particle size) powder, average particle size
0.4 μm Al ₂ O ₃ powder (99.99%), Cr with average particle size of 1.2 μm
Table 1 was used using ₂ O ₃ powder, carbonyl Ni powder having an average particle size of 1.5 μm, and Cr ₃ C ₂ powder having an average particle size of 2.0 μm. Is an average particle size of 2 μm
A solid solution of Al ₂ O ₃ : Cr ₂ O ₃ = 50: 50 was used. Also, HP
Was pressurized at 200 kgf / cm ² . )). Each compounded powder shown in Table 1 was put together with a ZrO ₂ ball in a container lined with polyurethane, and wet-mixed with methanol for 48 hours. These mixed powders were subjected to hot press sintering (HP) or 1 ton under the conditions described in Table 1.
After rubber pressing at a pressure of / cm ² , vacuum (about 10 ^-1 Torr) or atmosphere sintering was performed to obtain a sintered body of the present invention and a comparative sintered body deviating from the present invention. Among them, for some samples,
After sintering, further in Ar gas, a pressure of 1500 atm, 1350 ° C-1
The hot isostatic pressure treatment (HIP treatment) was performed under the condition of time.

The hardness and transverse rupture strength of the sintered products of the present invention products 1 to 7 and comparative products 1 to 6 shown in Table 1 thus obtained were measured, and the respective structures were observed. Shown in the table.

In Table 2, a friction test was performed using the products 3 to 7 of the present invention and the comparative products 1, 2, 3, 5, and 6 under the following conditions (A), (B), and (C). The results are shown in Table 3 (where μ is the average friction coefficient, b is the width of the block wear mark, and W is the wear amount of the mating material).

(A) Wet friction test using Al as the mating material Test liquid Emulsion type Sample shape 6.2 × 10 × 16mm mating material Al material for cans (35φ × 10mm) Load 20kgf Revolution 200rpm time 20min (B) Carbon steel Oil supply friction test made of material Test liquid High-purity mineral oil Sample shape 6.2 × 10 × 16mm Counter material S20C (35φ × 10mm) Load 20kgf Rotation speed 200rpm Time 20min (C) Dry friction test using stainless steel as material 6.2 × 10 × 16mm Counterpart material SUS304 (35φ × 10mm) Load 2kgf Rotation speed 200rpm Time 20min Next, among the sintered bodies in Table 2, a cutting test was performed using the products 1, 2, and 6 of the present invention and the comparative products 2, 3, and 4 under the following conditions (D) and (E). The results are shown in Table 4.

Request (B) dry turning test chip shape SNGN 120408 Workpiece S48C average flank wear of cutting speed 400 meters / min Depth of cut 1.5mm feed Ri 0.2 mm / rev evaluation 10 minutes after cutting (V _B). However, abort if deficient or V _B becomes 0.4mm in the middle.

(E) Dry milling test Chip shape SNGN 120408 Work material FCD60 (300 × 150mm surface) Cutting speed 140m / min Depth of cut 1.5mm Evaluation Cut from feed 0.1mm / rev and cut 300 × 15
When the cutting of the 0 mm surface is completed, the feed is increased, and the maximum feed that can be cut is displayed.

(Effect of the Invention) The highly wear-resistant composite sintered body of the present invention is a comparative product deviating from the product of the present invention, a conventional Al ₂ O ₃ —ZrO ₂ —Cr ₂ O ₃ ternary composite sintered body and Al Compared to ₂ O ₃ -ZrO ₂ binary composite sintered body, hardness and bending strength tend to be higher, friction coefficient tends to be lower, damage amount to mating material during friction test is When used as a cutting tool, there is a tendency to have excellent wear resistance, and there is an effect that fracture resistance is remarkably excellent due to high welding resistance and lubricity. Therefore, it is an industrially useful sintered body.

Continuation of the front page (56) References JP-A-2-129066 (JP, A) JP-A-2-34556 (JP, A) JP-A-1-157462 (JP, A) JP-A-63-195166 (JP) , A) JP-A-61-201661 (JP, A) Japanese Translation of PCT International Publication No. 3-513152 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C04B 35/10 C04B 35/12 C04B 35/42-35/49 CA (STN) REGISTRY (STN)

Claims (5)

(57) [Claims] 1. A composite sintered body comprising at least one metal phase of at least 10% by weight of Cr, Co, Ni, Fe and their mutual alloys, with the balance being a metal oxide phase and unavoidable impurities. Yes,
The metal oxide phase contains 10 to 85% by weight of zirconium oxide and 10 to 72% by weight of chromium oxide containing 1 to 5% by mole of at least one of MgO, CaO, rare earth oxides and their mutual solid solutions. A highly wear-resistant composite sintered body characterized in that the aluminum content is 5 to 80% by weight. 2. A composite sintered body comprising 30% by weight or less of chromium carbide and a balance of a metal oxide phase and unavoidable impurities,
The metal oxide phase contains 10 to 85% by weight of zirconium oxide and 10 to 72% by weight of chromium oxide containing 1 to 5% by mole of at least one of MgO, CaO, rare earth oxides and their mutual solid solutions. A highly wear-resistant composite sintered body characterized in that the aluminum content is 5 to 80% by weight. 3. At least one metal phase in Cr, Co, Ni, Fe and their alloys is not more than 10% by weight, chromium carbide is not more than 30% by weight, and the remainder is inevitably a metal oxide phase. A composite sintered body composed of impurities and the metal oxide phase is MgO,
Zirconium oxide containing 10 to 5 mol% of at least one of CaO, rare earth oxides and mutual solid solutions thereof
A highly wear-resistant composite sintered body comprising 85% by weight, 10 to 72% by weight of chromium oxide and 5 to 80% by weight of aluminum oxide. 4. The high wear resistant composite according to claim 1, wherein the zirconium oxide is partially or entirely tetragonal. Sintered body. 5. A method according to claim 1, wherein a part or all of said chromium oxide and said aluminum oxide are in a mutual solid solution.
Item 5. The highly wear-resistant composite sintered body according to item 4 or 4.