JP3148028B2 - Black silicon nitride sintered body and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a black silicon nitride sintered body having a black integrated reflectance of 15% or less for visible light and ultraviolet light (hereinafter referred to as an integrated reflectance of visible light and ultraviolet light). Is simply referred to as reflectance. The integrated reflectance means the ratio between the amount of incident light and the total amount of light reflected in all directions).

2. Description of the Related Art There are many parts related to light, such as a laser using apparatus and an ultraviolet exposure apparatus, which do not want to reflect light.

[0003] For these components, a material having a black color tone and a low reflectance is required. In many cases, these parts are required to be lightweight parts, high rigidity, low thermal expansion, abrasion resistance and the like at the same time as precision parts.

The black silicon nitride sintered body of the present invention is most suitable for these parts, and is widely applied to such parts.

Hereinafter, silicon nitride and sialon are collectively referred to as silicon nitride.

[0006]

2. Description of the Related Art Conventionally, as such a component, a component in which the surface of an aluminum alloy is treated with black alumite is often used because of its low reflectance and light weight.

However, the precision and life required of machines using these parts have recently become severe, and aluminum alloys have low rigidity (elasticity), are easily plastically deformed, have a high coefficient of thermal expansion, and have high wear resistance. Properties such as poor quality are problematic.

Therefore, there are attempts to apply ceramics to these parts, but many ceramics are not found to be materials that sufficiently satisfy black (low reflectance), high rigidity, light weight, low thermal expansion, and abrasion resistance. Absent.

[0009] Japanese Unexamined Patent Publication No. 04-5016 disclosed by us.
No. 1 discloses a technique for coloring an amylna sintered body in black.

However, although the coefficient of thermal expansion of alumina is smaller than that of metal, it cannot be said that it is still sufficient, and its abrasion resistance is not sufficient.

On the other hand, the thermal expansion coefficient of silicon nitride is 1/3 or less of that of alumina, and the wear resistance is very excellent. The specific gravity is as low as 80% of that of alumina, which is superior when a lighter weight is required.

However, silicon nitride-based sintered bodies are generally light gray to gray, and have a large reflectance of 20 to 35%.

As a technique for coloring the silicon nitride-based material, there is a technique for adding about 30% of TiN to give a golden color. However, the reflectivity does not decrease so much in the golden color.

Other coloring techniques are described in JP-A-62-248773 and JP-A-01-192766.
A black silicon nitride sintered body is disclosed.

The former is blackened by adding compounds of Sc, Yb, Er, Ho and Dy, and the latter is blackened by adding an organic metal compound containing Co or Fe, which is different from the present invention.

Japanese Patent Application Laid-Open No. 62-235260 discloses that at least one of TiN, TiC and Ti (CN) is added to silicon nitride for 5 to 40 watts.
Although a sintered body which is HIP-sintered by adding t% is disclosed, if such additives are added in such a large amount, the specific gravity increases, and the sinterability is impaired, so that pressure sintering of HIP / HP or the like is performed. Is required, resulting in an expensive sintered body due to the firing cost.

No mention is made of the color or reflectance.

[0018]

As described above, there is no metal material which satisfies high rigidity, low thermal expansion, light weight and wear resistance at the same time.

Further, the reflectance of ceramics is 1
There are various materials with 5% or less, but high rigidity, low thermal expansion,
From the viewpoint of light weight and wear resistance, a silicon nitride-based material is optimal.

However, the reflectance of a silicon nitride-based material is 20
Up to 30%, and a coloring method for lowering the reflectance has not been obtained.

[0021]

The problem of blackening the above silicon nitride-based sintered body to have a reflectance of 15% or less is as follows.
TiC, TiC-TiN solid solution, NbC,
One or more of ZrC, HfC and TaC is 0.2
-5% by weight, and V, Cr, F
e, one or more of Co, Ni, Cu, and Hf are contained as a metal or an oxide in an amount of 0.1 to 5 wt%, and the balance is substantially a silicon nitride-based material. Under pressure or gas pressure of 10 kgf / cm ² or less
The problem is solved by sintering in a temperature range of 600 to 1850 ° C.

In this manner, a low (blackened) silicon nitride material having a reflectance of 15% or less can be obtained at low cost.

TiC, TiC-TiN solid solution, NbC,
If the addition amount of one or more of ZrC, HfC and TaC is more than 5 wt%, sintering of silicon nitride is hindered, and a sufficiently dense sintered body cannot be obtained without pressurization. Is extremely reduced, and various mechanical properties are reduced.

Further, these additives have a higher coefficient of thermal expansion and a higher specific gravity as compared with silicon nitride-based ones, so that when added in large amounts, the coefficient of thermal expansion is large, the weight becomes heavy and the performance is reduced.

When the content is less than 0.2 wt%, the black coloration becomes insufficient and the reflectance does not decrease.

Although the amount of addition varies depending on the additive, it is preferably about 1 wt% to 3 wt%, and it is possible to produce a dense, high-rigidity, low-thermal-expansion silicon nitride-based sintered body having a sufficient black color tone and a low cost. .

The color tone adjusting agent may be used to stabilize the black color tone, since color unevenness or shading may occur only with the above blackening additive.

These color tone adjusting agents include V, Cr, Fe, C
It is preferable to add one or more of o, Ni, Cu, and Hf as metal or oxide in an amount of 0.2 to 5% by weight.

The amount of addition is 1 to 5 wt% for V, Cr and Fe as oxides, and 0.5 to 4 w for Co, Ni and Cu.
In the case of t% and Hf, 0.2 to 1.5 wt% is optimal. If the amount is too small, the adjustment effect is small.

The silicon nitride-based material means silicon nitride and sialon, and sialon includes α-sialon and β-sialon.

In the case of silicon nitride, the compounded powder mixture comprises silicon nitride powder and its sintering aid powder.

The sintering aid referred to here is Y ₂ O ₃ , Al
₂ O ₃ , MgO, SiO ₂ , Yr ₂ O ₃ , Er ₂ O ₃ , Sc ₂ O
One or several combinations such as ₃

On the other hand, in the case of sialon, the compounded mixed powder may be composed of sialon powder and a sintering aid thereof, or may be composed of silicon nitride powder which becomes sialon after sintering and other powders.

The particle size of the powder used as the raw material is preferably 10 μm or less, particularly preferably 5 μm or less from the viewpoint of sinterability.

With a powder having a larger particle size, a sufficiently dense sintered body cannot be obtained, so that a sufficiently high rigidity and abrasion resistance may not be obtained.

The sintering is performed in a nitrogen atmosphere.
No force, ambient pressure is 10kgf / cm^Two Implemented below
Is cheaper than high pressure sintering such as HP and HIP
Various complicated shapes can be fired.

As for the sintering temperature, when the raw material has a small particle size and the sintering aid is sufficiently large, sintering can be performed at a low temperature of about 1600 to 1750 ° C., but TiC, TiC—TiN solid solution, NbC, ZrC , HfC, TaC, or 2
1700 to 1800 ° C. when the amount of addition of more than one species is large and the sintering aid is small, or when the particle size of the raw material powder is large
is necessary.

Decomposition of silicon nitride and sialon occurs at 1800 ° C. or higher, but it is performed under atmospheric pressure (10 kgf / cm ^2).
When the following is used, sintering at a high temperature up to about 1850 ° C. is possible.

The sintered body thus produced has a black color tone, has a low integrated reflectance of visible light and ultraviolet light of 15% or less, and has high rigidity, wear resistance and low thermal expansion. .

TiC, TiC-TiN solid solution, NbC,
One or more of ZrC, HfC and TaC are added in a sufficiently large amount, and when the color additive is added appropriately, 1
A low reflectance of 0% or less is obtained.

Hereinafter, the present invention will be described specifically with reference to examples.

[0042]

Example 1 Silicon nitride powder having an average particle size of 0.2 μm
4.8 parts by weight of MgO as a sintering aid and 4 parts by weight of Al ₂
4.8 parts by weight of O ₃ , Ti having an average particle size of 1 μm as a colorant
3 parts by weight of a resin binder was added to a mixed powder consisting of 3 parts by weight of C powder and 2 parts by weight of iron oxide as a color tone adjuster, and mixed in an alumina pot mill using water as a solvent for 24 hours.

The slurry was dried and granulated, and the hydrostatic pressure was 200
It was molded at 0 kg / cm ² . The obtained molded body was N ₂ gas 1
The temperature was raised in the atm, and sintering was performed at 1750 ° C. for 2 hours.

The bulk density of the obtained sintered body was a theoretical density of 9
8.0%, a Young's modulus of ^{3.1 × 10 4 kgf / mm 2} , bending strength reflectivity color is a black 85 kgf / mm ² was 9.2% between wavelengths 350 to 800 nm. Also 2
The coefficient of thermal expansion from 0 ° C. to 100 ° C. was 2.0 × 10 ⁻⁶ / ° C.

[0045]

Example 2 4.7 parts by weight of Y ₂ O ₃ as a sintering aid were added to 83.6 parts by weight of β-sialon powder having an average particle size of 0.7 μm.
4.7 parts by weight of Al ₂ O _3, 5 parts by weight of Ti (CN) powder having an average particle size of 1 μm as a colorant, and CoO 2 as a color tone adjuster
3 parts by weight of the resin binder was added to the mixed powder consisting of parts by weight, and mixed in an alumina pot mill using water as a solvent for 24 hours.

The slurry was dried and granulated, and the hydrostatic pressure was 200
0kg / cm^TwoMolded. The obtained molded body is N _TwoGas 1
The temperature was raised in 0 atm, and sintering was performed at 1850 ° C. for 2 hours.

The bulk density of the obtained sintered body was 9% of the theoretical density.
8.5%, a Young's modulus of ^{3.2 × 10 4 kgf / mm 2} , bending strength color tone 78kgf / mm ² is reflectance black brown was 11.5% at a wavelength between 350 to 800 nm. The coefficient of thermal expansion at 20 ° C to 100 ° C is 1.8 × 10 ^-6 / ° C.
Met.

[0048]

Example 3 Powder prepared so that Z value becomes 2 after sintering
Powder (silicon nitride powder + Y _TwoO_Three+ Al_TwoO_Three+ AlN) 97 layers
NbC powder having an average particle size of 0.8 μm as a coloring agent
2 parts by weight, Hf as a color adjusting agent_TwoO_ThreeMix 1 part by weight
Then, 3 parts by weight of a resin binder are added, and alcohol is dissolved in a solvent.
For 24 hours in an alumina pot mill.

The slurry was dried and granulated, and the hydrostatic pressure was 200
0kg / cm^Two Molded. The obtained molded body is N_TwoGas 1
The temperature was raised in 0 atm, and sintering was performed at 1850 ° C. for 2 hours.

The bulk density of the obtained sintered body was 9% of the theoretical density.
7.8%, Young's modulus is 3.0 × 10^Four kgf / mm^Two, Song
Baling strength is 68kgf / mm^TwoThe color tone is black-brown and the reflectance is
It was 12.2% between the wavelengths of 350 to 800 nm. Ma
The thermal expansion coefficient at 20 ° C to 100 ° C is 1.9 × 10^-6/ ℃
Met.

[0051]

EXAMPLE 4 88.0 parts by weight of α-sialon powder having an average particle diameter of 0.3 μm, ΔgO5 parts by weight as a sintering aid, 5 parts by weight of TaC powder having an average particle diameter of 1 μm as a colorant, and a color tone adjusting agent To a mixed powder composed of 1 part by weight of NiO and 1 part by weight of iron oxide, 3 parts by weight of a resin binder was added, and mixed in an alumina pot mill using alcohol as a solvent for 24 hours.

The slurry was dried and granulated, and the hydrostatic pressure was 200
0kg / cm^TwoMolded. The obtained molded body is N _TwoGas 1
The temperature was raised in the atm and sintering was performed at 1750 ° C. for 2 hours.

The bulk density of the obtained sintered body was 9% of the theoretical density.
7.7%, Young's modulus is 3.2 × 10^Four kgf / mm^Two, Song
Baling strength is 65kgf / mm^TwoThe color is black and the reflectance is wave
It was 10.5% between 350 and 800 nm in length. Also
The coefficient of thermal expansion at 20 ° C. to 100 ° C. is 2.1 × 10^-6/ ℃
there were.

[0054]

Embodiment 5 Silicon nitride powder having an average particle size of 0.2 μm, 91 layers
Y as a sintering aid in parts _TwoO_Three5 parts by weight, Al_TwoO_Three4 weight
Colorant and color tone adjustment for silicon nitride mixed powder consisting of
The ingredients were mixed in the proportions shown in Table 1 and 3 parts by weight of the resin binder was added.
24 hours in an alumina pot mill using water as a solvent
Mixed.

The slurry was dried and granulated, and the hydrostatic pressure was 200
It was molded at 0 kg / cm ² . The obtained molded body was N ₂ gas 1
The temperature was raised in the atm, and sintering was performed at 1750 ° C. for 2 hours.

Table 1 shows the bulk density, Young's modulus, bending strength, reflectivity, and coefficient of thermal expansion at 20 ° C. to 100 ° C. of the obtained sintered body.

[0057]

[Comparative Example] Y ₂ O ₃ 5 parts by weight silicon nitride powder 91 parts by weight of the average particle diameter of 0.2μm as a sintering aid, colorant Ya against Al ₂ O ₃ 4 parts by weight of silicon nitride powder mixture consisting of The color tone adjusting agent was mixed at the ratio shown in Table 1, 3 parts by weight of a resin binder was added, and the mixture was mixed in an alumina pot mill using water as a solvent for 24 hours.

This slurry was dried and granulated, and the hydrostatic pressure was 200
It was molded at 0 kg / cm ² . The obtained molded body was N ₂ gas 1
The temperature was raised in the atm, and sintering was performed at 1750 ° C. for 2 hours.

Table 2 shows the bulk density, Young's modulus, flexural strength, reflectance, and coefficient of thermal expansion of the sintered body at 20 ° C. to 100 ° C.

[0060]

[Table 1]

[0061]

[Table 2]

[0062]

According to the present invention, a silicon nitride (silicon nitride / sialon) sintered body is colored black and has a reflectivity of 15% or less, which repels reflection and has high rigidity, low thermal expansion, and wear resistance. It can be widely applied to the manufacture of precision parts related to optical devices such as lasers and ultraviolet rays that require high performance.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-1-192766 (JP, A) JP-A-63-248773 (JP, A) JP-A-50-85479 (JP, A) JP-A-60-1985 42278 (JP, A) JP-A-1-120486 (JP, A) JP-A-5-51255 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C04B 35/584-35 / 596 C04B 35/599

Claims (5)

(57) [Claims] 1. A composition comprising 90% or more of one or more of silicon nitride and sialon, and TiC, TiC-TiN solution, NbC,
One or more of ZrC, HfC and TaC is 0.2
A black silicon nitride-based sintered body characterized in that it contains about 5% by weight and has an integrated reflectance of visible light and ultraviolet light of 15% or less. 2. V, Cr, Fe, C as color tone adjusting agents
2. The black silicon nitride sintered body according to claim 1, wherein one or several kinds of o, Ni, Cu, and Hf are added as metal or oxide in an amount of 0.2 to 5 wt%. 3. The thermal expansion coefficient at 20 to 100 ° C. is 2.5 ×
3. The method according to claim 1, wherein the temperature is 10 ^-6 / ° C. or less.
A black silicon nitride based sintered body as described in the above. 4. A Young's modulus of 2.8 × 10 ⁴ kgf / mm ²
4. The method according to claim 1, wherein:
Black silicon nitride sintered body according to. 5. A method according to claim 1-4 any one of the sintering temperature, characterized in that the sintering in a non-pressurized or 10 kgf / cm ² or less in a nitrogen atmosphere under pressure at 1,600 to 1,850 ° C.
Method of manufacturing a black silicon nitride sintered body according to.