JP2000219932A - Wear-resistant material - Google Patents

Abstract

(57) [Problem] To provide a wear-resistant member made of a sintered body containing aluminum oxide as a main component, which has low friction, excellent slidability, and excellent wear and corrosion resistance. A titanium carbide and / or boride is made of TiC.
And / or a total in terms of TiB ₂ from 3.0 to 35.0
Weight% and the weight ratio of carbon is 0.6 ≦ C / (C +
B) ≦ 1.0, wear resistance due to a sintered body containing titanium oxide and / or zirconium oxide in a total amount of 0.5 to 4.0% by weight and the balance substantially consisting of aluminum oxide Configure the members.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wear-resistant member made of a sintered body containing aluminum oxide as a main component, and is suitable as, for example, an injection nozzle used for a water jet machine or the like.

[0002]

2. Description of the Related Art Conventionally, as a material for forming a wear-resistant member such as an injection nozzle used in a water jet machine, a high-purity alumina sintered body or a silicon carbide sintered body having an alumina content of 99% by weight or more is used. Alternatively, there was one using a cemented carbide.

[0003]

By the way, the following requirements are desired for the above-mentioned injection nozzle.

[0004] 1) To be excellent in wear resistance and corrosion resistance.

2) Good slidability with water and abrasives (low friction coefficient).

[0006] 3) It is hard to break even when subjected to an impact.

4) A small-diameter nozzle hole is easily formed, and the workability is excellent.

[0008] However, when the injection nozzle is formed of a high-purity alumina sintered body, there is no fear of rust, and it is advantageous in that it is hard and has excellent wear resistance. There is a problem that it is difficult to process the nozzle hole because of the insulating material.

Further, when the injection nozzle is formed of a silicon carbide sintered body, there is a problem that the injection nozzle is easily broken due to low mechanical strength.

Further, in the case where the injection nozzle is made of a cemented carbide, since it has electrical conductivity, electric discharge machining can be used at the time of machining, and machining of nozzle holes and the like is easy, but lacks chemical stability. For this reason, there has been a problem that tribochemical wear resistance is poor and slidability is poor.

[0011]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a sintering material containing aluminum oxide as a main component, which has low friction, excellent wear resistance and corrosion resistance, is hardly damaged even when subjected to impact, and can be subjected to electric discharge machining. An object of the present invention is to provide a wear-resistant member made of a body.

[0012]

Therefore SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, 3.0 to 35.0 wt% containing carbides and / or borides of titanium in total in terms of TiC and / or TiB ₂ And the weight ratio of carbon is 0.6 ≦ C / (C + B)
≦ 1.0, containing titanium oxide and / or zirconium oxide in a range of 0.5 to 4.0% by weight in total, and abrasion-resistant members made of a sintered body substantially composed of aluminum oxide. It is composed. That is, according to the wear-resistant member of the present invention, the main component is aluminum oxide,
It contains a carbide and / or boride of titanium and titanium oxide and / or zirconium oxide in a specific range as auxiliary components, respectively, and has a feature that the surface of the sintered body has appropriate irregularities.

The titanium carbide and / or boride undergoes a solid-phase reaction with aluminum oxide in the sintered body to form T
Since iAlO ₂ and free carbon and / or free boron are generated, and the presence of the free carbon and / or free boron provides a lubricating effect and can reduce the friction coefficient, the sliding characteristics can be improved. In addition, the free carbon and / or free boron can promote the recrystallization solid solution substitution reaction to densify the sintered body.
The friction coefficient can be further reduced because an appropriate uneven surface as shown in FIG. Moreover, by containing titanium carbide, conductivity can be imparted, and electric discharge machining and the like can be performed.

However, if the total content thereof is less than 3.0% by weight in terms of TiC and / or TiB ₂ ,
The effect of enhancing the mechanical properties cannot be obtained, and the surface of the sintered body cannot be made to have an appropriate uneven surface, so that the slidability cannot be enhanced. Since the bondability is significantly deteriorated, the bending strength is reduced. Therefore, in the sintered body to form a wear-resistant member, carbides and / or borides of titanium to contain in the range of 3.0 to 35.0 wt% in terms of TiC and / or TiB ₂ is important.

Even if the total content of titanium carbide and / or boride is within the above range, if the weight ratio of carbon is 0.6> C / (C + B), that is, if the amount of titanium boride is too large, Since the sinterability is significantly impaired and the flexural strength of the wear-resistant member is greatly reduced, the weight ratio of carbon is 0.6 ≦ C /
It is necessary to satisfy (C + B) ≦ 1.0.

Titanium oxide and / or zirconium oxide have a function of strengthening the interparticle bonding force by a solid solution reaction with aluminum oxide in the sintered body.
It has a function as a sintering aid with carbides and borides of titanium, and when the total content is less than 0.5% by weight,
3. The bonding strength between particles and the effect as a sintering aid cannot be obtained;
If the content exceeds 0% by weight, the hardness of the wear-resistant member decreases, and the wear resistance deteriorates. Therefore, it is important that titanium oxide and / or zirconium oxide be contained in the sintered body forming the wear-resistant member in a range of 0.5 to 4.0% by weight.

In the present invention, since the balance is substantially made of aluminum oxide having high hardness and excellent corrosion resistance, the hardness and bending resistance are higher than those of a wear-resistant member made of a conventional high-purity alumina sintered body. In addition to significantly improving the mechanical strength such as the strength, the surface of the wear-resistant member can be made to have a moderately uneven surface because the particles having different diameters are included in the above range, and furthermore, it has conductivity. Member.

In the present invention, the expression that the balance substantially consists of aluminum oxide means that aluminum oxide, carbides and borides of titanium, impurities other than titanium oxide and zirconium oxide are contained in an amount of 1% by weight or less. Say that.

Further, in the wear-resistant member of the present invention, when the average crystal particle diameter of all the particles constituting the sintered body exceeds 3 μm, the mechanical properties such as hardness and flexural strength of the wear-resistant member are greatly reduced. However, it is difficult to reduce the thickness to less than 0.8 μm in manufacturing.

Therefore, the average crystal grain size of the sintered body is 0.8
To 3 μm, and preferably in the range of 1 to 2 μm.

In calculating the average crystal grain size of the sintered body, a cross section of the sintered body is taken by SEM photograph, and when an arbitrary line is drawn, the length of the line is determined by the number of particles on the line. The value obtained by dividing by the value was taken as the average crystal particle diameter.

Such a wear-resistant member has a bending strength of 55k.
g / mm ² or more, Vickers hardness 1800 kg / mm ²
In addition to having excellent mechanical properties as described above, the surface of the wear-resistant member is provided with free carbon and free boron having self-lubricating properties, and has moderate unevenness, so that it has a small friction coefficient and excellent slidability. Can be provided. Moreover, since it has electrical conductivity, it can be subjected to electrical discharge machining, so that it can be manufactured relatively easily even with a complicated shape.

In order to obtain such a wear-resistant member of the present invention, as a starting material, a total content of alumina powder having an average particle diameter of 1 to 3 μm and titanium carbide powder and / or boron carbide powder after sintering is contained. The amount is 3.0 to 35.0% by weight and the weight ratio of carbon is 0.6 ≦ C / (C + B) ≦ 1.0, and the titanium oxide powder and / or the zirconia powder are sintered. The mixture is then added so that the total content becomes 0.5 to 4.0% by weight, and further, a binder and a solvent are added and kneaded to produce a slurry, a casting method, an extrusion method, and an injection molding method. Molding into a predetermined shape by a well-known ceramic molding method such as, or drying granulation of the above-mentioned slurry to produce granules, filling in a mold, uniaxial pressure molding method, isopress molding method, etc. It is formed into a predetermined shape by a well-known ceramic molding method. Then, the obtained molded body is placed in a vacuum atmosphere for 1 hour.
It can be obtained by firing at a temperature of 500 to 1800 ° C. In the firing, hot pressing may be performed.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which an injection nozzle used for a water jet machine is formed by using the wear-resistant member of the present invention will be described.

First, as a starting material, the average particle size is 2 μm.
88.7% by weight of alumina powder, 8.5% by weight of titanium carbide powder, 0.8% by weight of titanium boride, 1.1% by weight of titanium oxide, and 0.9% by weight of zirconia powder. After adding and blending and mixing and grinding for 15 hours, 6% by weight of paraffin wax is added and kneaded and filled into a caliber mold,
By extruding at a pressure of 5.0 ton / cm ² , a prototype injection nozzle having a through hole was formed.

The compact was fired at a temperature of 1650 ° C. for about 1 hour in a vacuum atmosphere of 10 ² torr or less to obtain a sintered body.

When the composition of this sintered body was measured by ICP (emission spectrophotometry), 8.5% by weight of titanium carbide was converted to titanium carbide and titanium boride was converted to titanium boride. 0.8% by weight, zirconium oxide is 0.1%
It was confirmed that 9% by weight and 1.1% by weight of titanium oxide were contained, and the remainder was aluminum oxide.

Further, in order to examine mechanical characteristics, JIS
When the Vickers hardness was measured according to the standard of Z 2244, it was found to be 1870 Kg / mm ² , and the flexural strength was measured by JI.
93 kg / m measured according to the standard of SR 1601
m ² .

When the surface of the mirror-polished sintered body was observed with a metallurgical microscope, the average crystal grain size was 2.0 μm.
Met.

Then, the obtained sintered body was subjected to electric discharge polishing to obtain an injection nozzle 1 having a tapered tip and a nozzle hole 2 at the tip face as shown in FIG.

[0031]

EXAMPLES Here, titanium carbide and / or boride,
A wear-resistant member made of a sintered body containing aluminum oxide as a main component and having different contents of titanium oxide and / or zirconium oxide, and an alumina sintered body having a purity of 99.5% and a purity of 99.5 as a conventional example. % Of silicon carbide sintered bodies, and the mechanical properties of Vickers hardness and bending strength were examined, and the friction coefficient and the degree of wear were measured.

In measuring, the Vickers hardness was measured according to JIS.
According to the standard of Z 2244, the bending strength is JIS R
Each was measured according to the standard of 1601.

As shown in FIG. 3, the measurement of the coefficient of friction is performed by using a test yarn 21 and arranging the test yarn 21 on the inner surface of the ring-shaped sample 10 so that the contact angle θ is 90 °. Sliding at a speed of 1000 m / min, the input side tension T ₁
Was set to 20 gf, the output side tension T ₂ was measured, and the friction coefficient (μ) was calculated by the following Amonton's law.

Μ = ln (T ₂ / T ₁ ) / θ Further, the degree of wear was evaluated using a tester similar to that shown in FIG.
The distance of the test yarn 21 is 50 while the water mixed with
The test was performed until the length reached 00 m. Thereafter, the inner surface of the sample 10 was magnified by about 20 times and observed with a binocular microscope. When no wear mark was observed, the result was ○, when a little wear mark was observed, and when the wear mark was clearly seen. It was judged as x.

The results are as shown in Table 1.

[0036]

[Table 1]

As a result, the sample No. The high-purity alumina sintered body of Sample No. 2 has not so large bending strength and Vickers hardness. Silicon carbide No. 1 had a high coefficient of friction because the surface was relatively smooth. In both cases, some wear marks were observed, and both were inferior in wear resistance.

Sample No. Sample No. 9 had a total content of carbide and boride of titanium of more than 35% by weight in terms of TiC and TiB ₂ . 7 has a carbon weight ratio of 0.1.
Since it was 6 or less, the bending strength and Vickers hardness were all low.

On the other hand, the sample No. 3-6,8, the titanium carbide and / or boride is TiC
And / or a total in terms of TiB ₂ from 3.0 to 35.0
% By weight, and the weight ratio of carbon is 0.6 ≦ C / (C + B)
≦ 1.0 and containing titanium oxide and / or zirconium oxide in a total range of 0.5 to 4.0% by weight, the flexural strength is 55 kg / mm ² or more and the Vickers hardness is 1800 kg / With excellent mechanical properties of ² mm or more, and with free carbon or free boron having self-lubricating properties on the surface of the sintered body, and having moderate irregularities, the coefficient of friction is 0.3 or less and low friction. Furthermore, it was confirmed that the wear-resistant member of the present invention had low friction, excellent slidability, and excellent wear resistance.

[0040]

As described above, according to the present invention, the carbide and / or boride of titanium is converted to TiC and / or TiB _2.
And the weight ratio of carbon is 0.6 ≦ C / (C + B) ≦ 1.0, and titanium oxide and / or zirconium oxide in total Since the wear-resistant member was formed from a sintered body substantially composed of aluminum oxide, the flexural strength was 55 kg / mm ² or more, and the Vickers hardness was 1800 kg /. It has excellent mechanical strength of not less than ² mm2, excellent wear resistance and corrosion resistance, and has moderate unevenness on the surface, so that it has a small friction coefficient and excellent slidability. Moreover, since it has conductivity, electric discharge machining can be performed in machining. Therefore, by using the wear-resistant member of the present invention, it is possible to manufacture an injection nozzle having a fine nozzle hole accurately and relatively easily as used in a water jet processing machine, and to slide with low friction. Since it has excellent properties, and is excellent in wear resistance and corrosion resistance, it can be favorably used for a long period of time as compared with conventional injection nozzles.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a composition of a sintered body forming a wear-resistant member of the present invention.

FIG. 2 is a perspective view showing an injection nozzle used for a water jet processing machine comprising the wear-resistant member of the present invention.

FIG. 3 is a schematic diagram for explaining a method of measuring a coefficient of friction.

[Explanation of symbols]

1: injection nozzle 2: nozzle hole 10: sample 21; test yarn

Claims (1)

[Claims] 1. A titanium carbide and / or boride is made of TiC
And / or a total in terms of TiB ₂ from 3.0 to 35.0
Weight% and the weight ratio of carbon is 0.6 ≦ C / (C +
B) ≦≦ 1.0, and a sintered body containing titanium oxide and / or zirconium oxide in a total amount of 0.5 to 4.0% by weight, and the balance substantially consisting of aluminum oxide A wear-resistant member characterized by the above-mentioned.