JP6989102B2 - Manufacturing method of zinc sulfide sintered body and zinc sulfide sintered body - Google Patents

Description

The present invention relates to a zinc sulfide sintered body and a method for producing a zinc sulfide sintered body.

Various methods for producing a zinc sulfide sintered body and a zinc sulfide sintered body have been proposed (see, for example, Patent Documents 1, 2, 3 and the like).

Patent Documents 1, 2 and 3, respectively, disclose a zinc sulfide sintered body having predetermined optical properties and a method for producing the same. For example, Patent Document 1 discloses a zinc sulfide sintered body having a high transmittance of far-infrared light, and a method for producing the same. Further, Patent Document 2 discloses a zinc sulfide sintered body having a high transmittance of far-infrared light and a high light-shielding property of near-infrared light, and a method for producing the same. Patent Document 3 discloses a zinc sulfide sintered body having a high transmittance in a wavelength in the mid-infrared region, and a method for producing the same.

Japanese Unexamined Patent Publication No. 2007-31208 Japanese Unexamined Patent Publication No. 2008-195593 Japanese Patent Application Laid-Open No. 2015-189622

In an optical device such as an analysis camera or a night-vision camera using infrared rays, for example, the zinc sulfide sintered body used as a window material or a lens material preferably has a high light transmittance in the mid-infrared region.

In order to improve the light transmittance in the mid-infrared region of the zinc sulfide sintered body, the following methods can be considered.

First, as a pretreatment for the zinc sulfide sintering treatment, a method of refining the zinc sulfide powder can be considered. For example, it is conceivable to manufacture a zinc sulfide sintered body by reducing the particle size of the zinc sulfide powder to 1 μm or less and sintering the powder. Hereinafter, this method will be referred to as a first method.

Secondly, as a post-treatment of the zinc sulfide sintering treatment, a method of performing a hot isostatic pressing (HIP) treatment on the zinc sulfide sintered body can be considered. Hereinafter, this method will be referred to as a second method. In the sintering treatment, pressure is applied in the uniaxial direction, whereas in the HIP treatment, pressure is applied to the sintered body at a high temperature from all directions using gas or the like.

Thirdly, a method of applying an ultrahigh pressure using a molding die made of a special material can be considered. Hereinafter, this method will be referred to as a third method.

Fourth, as a condition for the zinc sulfide sintering process, the application of the load is started when the vicinity of the sintering temperature is reached, the load applied to the zinc sulfide powder is increased, and the temperature of the powder is sintered. A method of applying the maximum load when the temperature is reached can be considered. Hereinafter, this method will be referred to as a fourth method.

The first method has a problem that impurities may be mixed in when the zinc sulfide powder is miniaturized. Impurity contamination causes performance non-uniformity. Further, if the powder is fine, it becomes difficult to fill the molding die with the powder. Therefore, the first method is not suitable for producing a large zinc sulfide sintered body.

The second method has a problem that the cost required for HIP processing is high. Further, there is a problem that the mechanical strength of the zinc sulfide sintered body is lowered.

In the third method, since the molding die is made of a special material, the manufacturing cost is high. Further, there is a problem that the molding die may be damaged because an ultrahigh pressure is applied.

In the fourth method, since no special treatment is performed, a sintered body that transmits light in the mid-infrared region can be obtained at low cost, but it is transmitted by scattering and absorption of light due to impurities contained in the powder. There is a problem that the rate is low.

It is also conceivable to manufacture optical materials used as window materials, lens materials, etc. in optical devices by the chemical vapor deposition (CVD) method instead of the pressure sintering method to improve the optical characteristics. Be done. However, the CVD method has a problem of using a toxic gas. Further, since the vapor deposition rate from the vapor phase is extremely slow, the productivity of the optical material is low in the CVD method. Therefore, the manufacturing cost is high.

An object of the present invention is to provide a zinc sulfide sintered body and a method for producing a zinc sulfide sintered body, which have very excellent light transmittance in the mid-infrared region and are inexpensive.

The zinc sulfide sintered body according to the first aspect of the present invention has a light transmittance of 60% or more and 75% or less in the entire wavelength range of 3 μm or more and 5 μm or less when the thickness is 5 mm.

In the method for producing a zinc sulfide sintered body according to the second aspect of the present invention, the zinc sulfide powder is placed in a mold, heating of the zinc sulfide powder is started, and the temperature of the zinc sulfide powder is raised. Before the temperature of the zinc sulfide powder reaches the sintering temperature, the zinc sulfide powder is heated at a prebake temperature lower than the sintering temperature, and the temperature of the zinc sulfide powder is higher than the prebaking temperature. When the temperature near the sintering temperature, which is lower than the sintering temperature, is reached, the application of the load to the zinc sulfide powder is started, the load applied to the zinc sulfide powder is increased, and the sulfide is applied. When the temperature of the zinc powder reaches the sintering temperature, a maximum load is applied to the zinc sulfide powder, and after the temperature of the zinc sulfide powder reaches the sintering temperature, the zinc sulfide powder is used. while maintaining the temperature in the sintering temperature, a method for producing a zinc sulfide sintered compact to maintain the application of the maximum load for the powder of the zinc sulfide.

According to the present invention, it is possible to provide a zinc sulfide sintered body and a method for producing a zinc sulfide sintered body, which have very excellent light transmittance in the mid-infrared region and are inexpensive.

It is explanatory drawing which shows an example of the manufacturing apparatus of the zinc sulfide sintered body used for manufacturing the zinc sulfide sintered body which concerns on embodiment of this invention. It is a flowchart which shows the flow of the manufacturing method of the zinc sulfide sintered body which concerns on embodiment of this invention. It is explanatory drawing which shows the other example of the manufacturing apparatus of the zinc sulfide sintered body which concerns on embodiment of this invention. It is a graph which shows the transmittance characteristic of the zinc sulfide sintered body produced by the manufacturing method of the zinc sulfide sintered body which concerns on embodiment of this invention. It is a table which shows the specific value of the transmittance characteristic shown in FIG.

[Embodiment]
The zinc sulfide sintered body according to the embodiment of the present invention has a light transmittance of 60% or more in a wavelength range of 3 μm or more and 5 μm or less when the thickness of the zinc sulfide sintered body is 5 mm.

When the thickness is 5 mm, the transmittance of light in the wavelength range of 3 μm or more and 5 μm or less may be included in the range of 60% or more and 75% or less.

When the thickness is 5 mm, the transmittance of light in the wavelength range of 3 μm or more and 5 μm or less may be 64% or more. Further, when the thickness is 5 mm, the transmittance of light in the wavelength range of 3 μm or more and 5 μm or less may be 64% or more and 69% or less.

Further, when the thickness is 5 mm, the transmittance of light in the wavelength range of 8 μm or more and 12 μm or less may be 39% or more.

The above-mentioned light transmittance is a transmittance measured as a linear transmittance.

Further, the wavelength range of 3 μm or more and 5 μm or less corresponds to the mid-infrared region. If the zinc sulfide sintered body has a light transmittance of 50% or more in this wavelength range when the thickness is 5 mm, it has good optical properties in an optical device such as an analysis camera or a night-vision camera using infrared rays. It can be used as a material. Further, if the transmittance of this wavelength is 60% or more, the performance of the optical device can be further improved. For example, the zinc sulfide sintered body according to the embodiment of the present invention can be preferably used as a window material or a lens material. Here, the window material and the lens material are exemplified, but these are examples and do not limit the present invention. The zinc sulfide sintered body according to the embodiment of the present invention may be used as a material for other members of an optical device using infrared rays.

Further, as described above, when the thickness is 5 mm, the transmittance of light in the wavelength range of 8 μm or more and 12 μm or less may be 39% or more. Further, the transmittance of light in the wavelength range of 8 μm or more and 12 μm or less when the thickness is 5 mm may be included in the range of 39% or more and 80% or less. In these cases, the transmittance can be improved even in the wavelength range of 8 μm or more and 12 μm or less.

The zinc sulfide sintered body according to the embodiment of the present invention is not limited to a thickness of 5 mm. Even if the thickness is not 5 mm, the zinc sulfide sintered body that can obtain the above-mentioned transmittance characteristics when cut out to a thickness of 5 mm is the zinc sulfide sintered body according to the embodiment of the present invention. include.

[Production method]
Next, a method for producing the above zinc sulfide sintered body will be described. First, the manufacturing apparatus used in this manufacturing method will be described.

FIG. 1 is an explanatory diagram showing an example of an apparatus for manufacturing a zinc sulfide sintered body used in the method for manufacturing a zinc sulfide sintered body according to the embodiment of the present invention. FIG. 1 shows a manufacturing apparatus using the discharge plasma sintering method.

The manufacturing apparatus 100 shown in FIG. 1 is used to heat the molding die 1, the driving section 3 for moving the punch portion 13 of the molding die 1 in the uniaxial direction (vertical direction in FIG. 1), and the zinc sulfide powder. A voltage setting unit 2 to be formed and a container (hereinafter referred to as a chamber) 7 accommodating a molding die 1 and a drive unit 3 are provided.

The molding die 1 includes a side portion 11, a bottom portion 12, and a punch portion 13. The side portion 11 is formed so as to surround the space. The bottom 12 closes the lower opening of the side 11. The punch portion 13 includes a fitting portion 13a that fits into the inner wall of the side portion 11. The fitting portion 13a is slidable with respect to the side portion 11. The side portion 11 is formed of, for example, carbon. The bottom portion 12 and the punch portion 13 are formed of, for example, metal.

With the punch portion 13 pulled up by the drive portion 3, zinc sulfide powder is arranged in the space formed by the side portions 11 and the bottom portion 12. The drive unit 3 applies a load to the zinc sulfide powder by pushing the punch unit 13 downward.

The voltage setting unit 2 sets a voltage for each of the punch unit 13 and the bottom portion 12 so that a voltage difference is generated between the punch portion 13 and the bottom portion 12. As a result, an electric current flows through the side portion 11 of the molding die arranged between the punch portion 13 and the bottom portion 12, and the punch portion 13, the bottom portion 12, and the side portion 11 generate heat, and the zinc sulfide powder accompanies this. Is heated.

Further, when the voltage is set for the punch portion 13 and the bottom portion 12 so that a voltage difference is generated between the punch portion 13 and the bottom portion 12, zinc sulfide arranged between the punch portion 13 and the bottom portion 12 is provided. A current flows through the powder, but its distribution is smaller than the current flowing through the side 11.

Further, a thermometer 4 is arranged inside the side portion 11 of the molding die 1. The temperature indicated by the thermometer 4 can be regarded as the temperature of the zinc sulfide powder inside the molding die 1.

The drive unit 3 and the voltage setting unit 2 may operate according to the control of the control device (not shown), or may operate according to the operation of the operator. Hereinafter, a case where the drive unit 3 and the voltage setting unit 2 operate according to the control of the control device will be described as an example. In this case, the control device monitors the temperature indicated by the thermometer 4. When the operator operates the drive unit 3 and the voltage setting unit 2, the temperature indicated by the thermometer 4 may be displayed on an external display device (not shown) of the chamber 7 so that the operator can visually recognize the temperature. Just do it.

FIG. 2 is a flowchart showing an example of the processing process of the method for producing a zinc sulfide sintered body of the present invention. First, the zinc sulfide powder is placed in the molding die 1 (step S1). For example, with the punch portion 13 pulled up, the space formed by the side portion 11 and the bottom portion 12 is filled with zinc sulfide powder from the upper opening of the side portion 11. In step S1, after the powder is arranged, the drive unit 3 lowers the punch unit 13 until the lower surface of the fitting unit 13a comes into contact with the zinc sulfide powder under the control of the control device. In this state, the lower surface of the fitting portion 13a is only in contact with the zinc sulfide powder, and the load on the powder is negligible.

The zinc sulfide powder may be a commercially available high-purity zinc sulfide powder. Further, the particle size of the zinc sulfide powder may vary. For example, the zinc sulfide powder may have a particle size of about 1 μm to a particle size of about 10 μm, centering on a powder having a particle size of about 5 μm.

Next, the voltage setting unit 2 sets the voltage for the punch portion 13 and the bottom portion 12 so that a voltage difference is generated between the punch portion 13 and the bottom portion 12, respectively, according to the control of the control device. Heating of the zinc sulfide powder in 1 is started to raise the temperature of the zinc sulfide powder (step S2). As described above, the voltage difference between the punch portion 13 and the bottom portion 12 causes a current to flow through the side portion 11 arranged between the punch portion 13 and the bottom portion 12, and as a result, the zinc sulfide powder is heated. Ru. Then, the voltage setting unit 2 increases the voltage difference between the punch unit 13 and the bottom portion 12 to increase the amount of current, so that the temperature of the zinc sulfide powder rises. Here, it is preferable to adjust the temperature rise of the zinc sulfide powder so that the temperature rise of the zinc sulfide powder becomes 0.5 ° C./min to 5 ° C./min.

The temperature of the powder is raised and controlled so that the temperature becomes constant below the sintering temperature (step S3). This temperature is called the prebake temperature. By prebaking, impurities slightly contained in the powder are removed as a gas such as SOx by heating, and the powder becomes high-purity zinc sulfide. The prebake temperature is preferably 250 ° C to 750 ° C.

Here, the zinc sulfide powder may be heated to 250 ° C. to 750 ° C. in advance to remove impurities, cooled, and then heated again as the powder in the above step. Alternatively, the temperature rise due to heating in the temperature range of 250 ° C. to 750 ° C. may be made small, and the temperature may be controlled so as to have the same effect as maintaining a constant temperature during the temperature rise. In this case, the rate of temperature rise is preferably 0.01 ° C./min to 5 ° C./min.

When sintering a powder, the temperature of the powder is controlled to rise to a temperature below the melting point of the substance of the powder and is maintained at that temperature. This temperature is called the sintering temperature. The powder is sintered at the sintering temperature. When the zinc sulfide powder is sintered, the sintering temperature is preferably 850 ° C to 950 ° C.

When the temperature of the zinc sulfide powder reaches a temperature close to the sintering temperature, the drive unit 3 starts applying a load to the zinc sulfide powder by starting the descent of the punch unit 13 according to the control of the control device. (Step S4). Then, the drive unit 3 continues to lower the punch unit 13 to increase the load applied to the zinc sulfide powder (step S5). A temperature 100 ° C. lower than the sintering temperature may be used as the vicinity temperature used in step S4. The sintering temperature when the zinc sulfide powder is sintered is preferably 850 ° C to 950 ° C, and a temperature 100 ° C lower than this temperature can be said to be a temperature near the sintering temperature. For example, when 900 ° C. is adopted as the sintering temperature, the drive unit 3 may start applying a load to the powder at 800 ° C. (= 900-100). Further, for example, when 950 ° C. is adopted as the sintering temperature, the drive unit 3 may start applying the load to the powder at 850 ° C. (= 950-100).

Here, a case where the sintering temperature is 900 ° C. and the application of the load to the powder is started at 800 ° C. will be described as an example. The control device monitors the temperature indicated by the thermometer 4, and determines that the zinc sulfide powder has risen to 800 ° C. when the temperature indicated by the thermometer 4 reaches 800 ° C. Then, the control device may cause the drive unit 3 to start the descent of the punch unit 13 and continue the descent of the punch unit 13. Here, the case where the control device controls the drive unit 3 and the like is illustrated, but when the operator operates the drive unit 3 and the voltage setting unit 2, the operator monitors the temperature indicated by the thermometer 4. Then, when the temperature of the thermometer 4 reaches 800 ° C., the operator may operate the drive unit 3 to start the descent of the punch portion 13 and continue the descent of the punch portion 13.

As the punch portion 13 descends, the load applied to the zinc sulfide powder increases. Therefore, the load when the descent of the punch portion 13 is stopped becomes the maximum load applied to the zinc sulfide powder.

Then, when the temperature of zinc sulfide reaches the sintering temperature, the drive unit 3 applies the maximum load to the zinc sulfide powder by the punch unit 13 (step S6). In step S6, when a high load is applied at the sintering temperature, the zinc sulfide powder is sintered and becomes a zinc sulfide sintered body. When the side portion 11 is made of carbon, the maximum load of zinc sulfide on the powder is preferably 40 to 60 MPa in consideration of the resistance of carbon. Here, a case where the maximum load on the zinc sulfide powder is 50 MPa will be described as an example.

The control device monitors the temperature indicated by the thermometer 4 and the rate of temperature rise so that the maximum load (50 MPa in this example) is applied to the zinc sulfide powder when the zinc sulfide powder reaches 900 ° C. In addition, the drive unit 3 controls the speed at which the punch unit 13 is lowered. Then, when the temperature indicated by the thermometer 4 (that is, the temperature of the zinc sulfide powder) reaches 900 ° C., the control device causes the drive unit 3 to stop the descent of the punch unit 13, and causes the voltage setting unit 2 to sulfurize. Stop the temperature rise of the zinc powder. Stopping the descent of the punch portion 13 means stopping the increase of the load on the zinc sulfide powder. As a result, when the zinc sulfide powder reaches 900 ° C., a maximum load of 50 MPa is applied to the zinc sulfide powder. Here, the case where the control device controls the drive unit 3 and the like is illustrated, but when the operator operates the drive unit 3 and the voltage setting unit 2, the operator causes the temperature and temperature indicated by the thermometer 4. The rate at which the drive unit 3 lowers the punch portion 13 so that the ascending speed is monitored and the maximum load (50 MPa in this example) is applied to the zinc sulfide powder when the zinc sulfide powder reaches 900 ° C. Should be controlled.

After the zinc sulfide powder reaches the sintering temperature, the voltage setting unit 2 follows the control of the control device.
The temperature of the zinc sulfide powder in the mold 1 is maintained at the sintering temperature. Further, the drive unit 3 maintains the load on the zinc sulfide powder at the maximum load according to the control of the control device (step S7). In this state, sintering of the zinc sulfide powder proceeds, and the punch portion 13 is displaced in a method (downward direction) in which the zinc sulfide powder material arranged in the molding die 1 shrinks.

The voltage setting unit 2 and the drive unit 3 maintain the temperature of the zinc sulfide powder at the sintering temperature, and maintain the load on the zinc sulfide powder at the maximum load for a predetermined time. This predetermined time is, for example, 1 to 24 hours. Further, the time when the displacement of the punch portion 13 becomes zero is a guideline for the above-mentioned predetermined time.

Subsequently, the voltage setting unit 2 lowers the temperature of the zinc sulfide sintered body according to the control of the control device, and the drive unit 3 lowers the load on the zinc sulfide sintered body according to the control of the control device (step S8). ). In step S8, the temperature and the load may be lowered so that cracks due to the temperature difference between the upper side and the lower side of the zinc sulfide sintered body do not occur. Reducing the load means that the drive unit 3 raises the punch unit 13. To lower the temperature, the voltage difference between the punch portion 13 and the bottom portion 12 is made zero, or the voltage difference between the punch portion 13 and the bottom portion 12 is gradually reduced. It is realized by controlling.

When the voltage difference between the punch portion 13 and the bottom portion 12 is set to zero, heat generation of the punch portion 13, the bottom portion 12, and the side portion 11 is eliminated. As a result, heat flows to the drive portion 3 with which the punch portion 13 contacts and the stage (not shown) with which the bottom portion 12 contacts, so that the temperature drops at a high speed. Therefore, the temperature of the zinc sulfide sintered body also decreases at a high rate.

At this time, when the punch portion 13 is raised in order to reduce the load and the contact between the punch portion 13 and the zinc sulfide sintered body disappears, heat flow occurs only in the bottom 12 direction. Therefore, the temperature of the upper side of the zinc sulfide sintered body is high and the temperature of the lower side is low, and a temperature difference occurs between the upper side and the lower side of the zinc sulfide sintered body. When this temperature difference becomes large, the zinc sulfide sintered body cracks, so that the load of the zinc sulfide sintered body is reduced at an appropriate timing to reduce the temperature and the load.

On the other hand, when the voltage setting unit 2 is controlled so as to gradually reduce the voltage difference between the punch portion 13 and the bottom portion 12, the punch portion 13, the bottom portion 12, and the side portion 11 generate heat, and zinc sulfide is fired. The blotting can be lowered at the desired temperature. However, also in this case, if the punch portion 13 is raised, a temperature difference occurs between the upper side and the lower side of the zinc sulfide sintered body, so that the load of the zinc sulfide sintered body is lowered at an appropriate timing to reduce the temperature and load. To reduce.

For example, the longer the length of the zinc sulfide sintered body along the moving direction of the punch portion 13 (in this example, the higher the height of the zinc sulfide sintered body), the more the driving unit 3 is the zinc sulfide sintered body. (That is, slow down the ascending speed of the punch portion 13).

By the above method, the zinc sulfide sintered body according to the present invention can be produced as described above. This zinc sulfide sintered body has good light transmittance in the mid-infrared region (wavelength range of 3 μm or more and 5 μm or less), and is good in optical devices such as analysis cameras and night-vision cameras using infrared rays. It can be used as an optical material. Further, the transmittance of light in the wavelength range of 8 μm or more and 12 μm or less can be improved.

In the above description, the case where the drive unit 3 and the voltage setting unit 2 operate under the control of the control device has been described as an example. As described above, the drive unit 3 and the voltage setting unit 2 may operate according to the operation of the operator.

According to the above-mentioned production method, it is not necessary to perform a pretreatment for refining the zinc sulfide powder to 1 μm or less. Further, it is not necessary to perform HIP treatment on the zinc sulfide sintered body after step S7. The material of the molding die 1 may be carbon or metal, and it is not necessary to use a special material for the molding die 1. Furthermore, since impurities are sufficiently removed, the transmittance does not decrease due to residual impurities. Therefore, it is possible to produce a zinc sulfide sintered body having good light transmittance in the mid-infrared region at low cost without performing a treatment for refining the zinc sulfide powder or a HIP treatment. Therefore, the zinc sulfide sintered body can also be inexpensive.

Although it is not known why a zinc sulfide sintered body having good transmittance characteristics in a wavelength range of 3 μm or more and 5 μm or less can be obtained by the above-mentioned manufacturing method, the inventor of the present invention is as follows. I'm guessing the reason.

When the zinc sulfide powder is heated to a high temperature with impurities remaining, it becomes a gas in a state where the zinc sulfide powder is densified as a sintered body, so that it is not removed from the sintered body and remains as a gas to cause pores. These pores scatter the light incident on the inside of the sintered body and reduce the transmittance. Further, the residual impurities form a refractive index interface between the zinc sulfide of the mother body and the impurities, and the light is scattered at this interface to reduce the transmittance, and the transmittance is lowered by the light absorption of the impurities themselves. Therefore, the inventor has found that the removal of impurities is essential for achieving high transmittance, and the optimum prebake temperature is in the range of 250 ° C to 750 ° C. If the prebake temperature is lower than 250 ° C, impurities are not sufficiently removed, and if the prebake temperature is higher than 750 ° C, sintering proceeds, and impurities are taken into the sintered body and removed before they are removed. It may not be possible. The time for maintaining the prebake temperature at this time is preferably 30 minutes or more.

By keeping the zinc sulfide powder at the prebake temperature, the gas generated from the impurities can be almost completely removed, so that a high-purity sintered body can be obtained and good characteristics can be obtained. Is guessing as the reason.

As a means for heating the zinc sulfide powder to remove impurities, the first method is to start heating the zinc sulfide powder and then maintain the temperature below the sintering temperature of the zinc sulfide powder. Second, the zinc sulfide powder is heated in advance to remove impurities, and then the powder is used as the zinc sulfide powder in the above step. Thirdly, there is a method of controlling the temperature rise due to heating in a suitable temperature range so as to have the same effect as maintaining a constant temperature during the temperature rise.

In the first means, as the manufacturing process, only the heating program of the manufacturing apparatus for heating and sintering the zinc sulfide powder is adjusted, so that the process is not complicated. Since the zinc sulfide powder is heated in advance in the second means, there is a feature that the usage time of the manufacturing apparatus for sintering the powder can be shortened as compared with the first means. In the third means, in addition to the characteristics of the first means, it is not necessary to keep the temperature of the manufacturing device constant, so that the temperature control becomes easy, so that the temperature control of the manufacturing device such as a continuous furnace is difficult. Easy to apply to.

Further, the manufacturing apparatus used in the method for manufacturing a zinc sulfide sintered body according to the present invention is not limited to the configuration exemplified in FIG.

FIG. 3 is an explanatory diagram showing another example of the manufacturing apparatus for the zinc sulfide sintered body. The same elements as those shown in FIG. 1 are designated by the same reference numerals as those in FIG. 1, and detailed description thereof will be omitted.

The zinc sulfide sintered body manufacturing apparatus 100A shown in FIG. 3 does not include the voltage setting unit 2 shown in FIG. 1, but includes a heater 9 in the chamber 7. Then, the manufacturing apparatus 100A does not adopt the discharge plasma sintering method, but heats the entire inside of the chamber 7 by the heater 9 to heat the zinc sulfide powder. That is, while the manufacturing apparatus 100 shown in FIG. 1 heats mainly zinc sulfide powder by the discharge plasma sintering method, the manufacturing apparatus 100A heats the entire inside of the chamber 7 by the heater 9. Further, in the manufacturing apparatus 100A, the bottom portion 12 and the punch portion 13 may be formed of carbon instead of metal. Further, FIG. 3 shows a case where the thermometer 4 is arranged inside the side portion 11 as in FIG. 1, but in the configuration shown in FIG. 3, the thermometer 4 is on the side in the chamber 7. It may be arranged outside the part 11.

The drive unit 3 and the heater 9 may be operated according to the control of the control device (not shown), or may be operated according to the operation of the operator.

Even when the manufacturing apparatus 100A shown in FIG. 3 is used, the method for manufacturing a zinc sulfide sintered body according to the embodiment of the present invention can be realized, and the zinc sulfide sintered body according to the embodiment of the present invention can be obtained. ..

The inventor of the present invention produced a zinc sulfide sintered body by the method for producing a zinc sulfide sintered body according to the embodiment of the present invention, and confirmed the permeability of the zinc sulfide sintered body. The prebake temperature was 400 ° C. and the holding was carried out for 4 hours. FIG. 4 is a graph showing an example of the transmittance characteristics of the zinc sulfide sintered body produced by the method for producing a zinc sulfide sintered body according to the present invention. Further, FIG. 5 is a table showing the transmittance at wavelengths of 3 μm, 4 μm, and 5 μm shown in FIG. 4, and the average transmittance in the wavelength range of 3 to 5 μm. Note that FIGS. 4 and 5 show the transmittance when the thickness of the zinc sulfide sintered body is 5 mm. As shown in FIG. 4, the transmittance in the wavelength range of 3 μm or more and 5 μm or less is 60% or more. Further, the transmittance in the wavelength range of 3 μm or more and 5 μm or less is included in the range of 60% or more and 75% or less. Further, as can be seen from FIGS. 4 and 5, the transmittance in the wavelength range of 3 μm or more and 5 μm or less is 64% or more. More specifically, the transmittance in the wavelength range of 3 μm or more and 5 μm or less is 64% or more and 69% or less.

The sintered body produced in the examples is different from the sintered body of [Patent Document 3] described above in that it is prebaked. Further, the transmittance of the sintered body produced in the examples is 10% or more higher than the transmittance of the sintered body of the above-mentioned [Patent Document 3] at an average value of a wavelength of 3 μm or more and 5 μm or less. Yes, it has a very good transmittance.

Further, as shown in FIG. 4, when the thickness is 5 mm, the transmittance of light in the wavelength range of 8 μm or more and 12 μm or less is 39% or more. Further, as shown in FIG. 4, the transmittance of light in the wavelength range of 8 μm or more and 12 μm or less when the thickness is 5 mm is included in the range of 39 % or more and 80% or less.

Some or all of the above embodiments may also be described, but not limited to:

(Appendix 1)
A zinc sulfide sintered body having a light transmittance of 60% or more in a wavelength range of 3 μm or more and 5 μm or less when the thickness is 5 mm.

(Appendix 2)
The zinc sulfide sintered body according to Appendix 1, wherein the light transmittance in the wavelength range of 3 μm or more and 5 μm or less is 60% or more and 75% or less when the thickness is 5 mm.

(Appendix 3)
The zinc sulfide sintered body according to Appendix 1 or 2, wherein the light transmittance in the wavelength range of 3 μm or more and 5 μm or less is 64% or more when the thickness is 5 mm.

(Appendix 4)
The zinc sulfide sintered body according to any one of Supplementary note 1 to 3, wherein the light transmittance in the wavelength range of 8 μm or more and 12 μm or less is 39% or more when the thickness is 5 mm.

(Appendix 5)
The zinc sulfide sintered body according to any one of Supplementary note 1 to Supplementary note 4, wherein the light transmittance in the wavelength range of 8 μm or more and 12 μm or less is 39% or more and 80% or less when the thickness is 5 mm.

(Appendix 6)
Place zinc sulfide powder in the mold and place it in the mold.
Heating of the zinc sulfide powder is started to raise the temperature of the zinc sulfide powder.
Before the temperature of the zinc sulfide powder reaches the sintering temperature, the zinc sulfide powder is heated to a prebake temperature lower than the sintering temperature.
When the temperature of the zinc sulfide powder reaches a temperature near the sintering temperature, which is higher than the prebake temperature and lower than the sintering temperature, the application of a load to the zinc sulfide powder is started. The load applied to the zinc sulfide powder is increased to increase the load.
When the temperature of the zinc sulfide powder reaches the sintering temperature, a maximum load is applied to the zinc sulfide powder.
After the temperature of the zinc sulfide powder reaches the sintering temperature, the zinc sulfide powder maintains the temperature of the zinc sulfide powder at the sintering temperature while maintaining the application of the maximum load to the zinc sulfide powder. It is a method of manufacturing a sintered body.
A method for producing a zinc sulfide sintered body, in which the zinc sulfide powder is heated at a temperature lower than the sintering temperature before it reaches the sintering temperature.

(Appendix 7)
The method for producing a zinc sulfide sintered body according to Appendix 6, wherein the zinc sulfide powder is heated at the prebaking temperature in the range of 250 ° C. to 750 ° C. before reaching the sintering temperature.

(Appendix 8)
The method for producing a zinc sulfide sintered body according to Appendix 6 or 7, wherein the temperature of the zinc sulfide powder is maintained in the range of 250 ° C to 750 ° C while the temperature is rising.

(Appendix 9)
The production of the zinc sulfide sintered body according to Appendix 6 or 7 , wherein the zinc sulfide powder is previously heated and cooled at the prebake temperature in the range of 250 ° C. to 750 ° C., and then the heating of the zinc sulfide powder is started. Method.

(Appendix 10)
Just as the temperature rise when the temperature of the powder zinc sulfide is the pre-bake temperature in the range of 250 ° C. to 750 ° C. in a temperature rise, the rate of the temperature rise 0.01 ° C. / min to 5 ° C. / minute The method for producing a zinc sulfide sintered body according to Appendix 6 or 7.

(Appendix 11)
The method for producing a zinc sulfide sintered body according to Appendix 6 or 7, wherein when the temperature of the zinc sulfide powder reaches a temperature 100 ° C. lower than the sintering temperature, the application of a load to the zinc sulfide powder is started. ..

1 ... Molding mold 2 ... Voltage setting unit 3 ... Drive unit 4 ... Thermometer 7 ... Chamber 9 ... Heater 11 ... Side 12 ... Bottom 13 ... Punch part 13a ... Fitting part

Claims (8)

In the case where a thickness of 5 mm, a light transmittance of at 5μm across a wavelength range more than 3μm is 75% or less 60%, sulfuric zinc sintered. The zinc sulfide sintered body according to claim 1, wherein the light transmittance in the entire wavelength range of 3 μm or more and 5 μm or less is 64% or more when the thickness is 5 mm. The zinc sulfide sintered body according to claim 1 or 2 , wherein the light transmittance in the entire wavelength range of 8 μm or more and 12 μm or less when the thickness is 5 mm is 39% or more. The zinc sulfide according to any one of claims 1 to 3 , wherein the light transmittance in the entire wavelength range of 8 μm or more and 12 μm or less is 39% or more and 80% or less when the thickness is 5 mm. Sulfide. Place zinc sulfide powder in the mold and place it in the mold.
Heating of the zinc sulfide powder is started to raise the temperature of the zinc sulfide powder.
Before the temperature of the zinc sulfide powder reaches the sintering temperature, the zinc sulfide powder is heated to a prebake temperature lower than the sintering temperature.
When the temperature of the zinc sulfide powder reaches a temperature near the sintering temperature, which is higher than the prebake temperature and lower than the sintering temperature, the application of a load to the zinc sulfide powder is started. The load applied to the zinc sulfide powder is increased to increase the load.
When the temperature of the zinc sulfide powder reaches the sintering temperature, a maximum load is applied to the zinc sulfide powder.
After the temperature of the zinc sulfide powder reaches the sintering temperature, the zinc sulfide powder maintains the temperature of the zinc sulfide powder at the sintering temperature while maintaining the application of the maximum load to the zinc sulfide powder. A method for manufacturing a sintered body. The method for producing a zinc sulfide sintered body according to claim 5 , wherein the temperature of the zinc sulfide powder is maintained in the range of 250 ° C to 750 ° C while the temperature is rising. The method for producing a zinc sulfide sintered body according to claim 5 , wherein the zinc sulfide powder is heated in advance at the prebake temperature in the range of 250 ° C. to 750 ° C. and cooled, and then the heating of the zinc sulfide powder is started. .. When the temperature of the zinc sulfide powder is in the range of 250 ° C to 750 ° C during the temperature rise, the temperature rise is slight, and the rate of the temperature rise is 0.01 ° C / min to 5 ° C / min. The method for producing a zinc sulfide sintered body according to claim 5.

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