JP2018142462A - Ceramic insulation member and electron tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ceramic insulation member in which adsorption of an alkali metal is small, and a reflection rate is low in a wide wavelength range.SOLUTION: A ceramic insulation member to be disclosed is made of an alumina ceramic including an oxidation of titanium of which a composition formula is expressed by TiO(1≤x<2), and a total content amount of Fe, Ni, Co, Mn, and Cr is 260 mass ppm or less. An electron tube to be disclosed comprises: a container including an incident window having a photoelectric surface; a plurality of electrode bodies positioned in the container; and a ceramic insulation member positioned in the container and nipping the plurality of electrode bodies.SELECTED DRAWING: Figure 1

Description

  The present disclosure relates to a ceramic insulating member and an electron tube.

  Ceramic insulating members are widely used. For example, a ceramic insulating member is used as a member that supports each electrode body while insulating each electrode body in an electron tube of a photomultiplier tube.

  Here, the photomultiplier tube is mainly used as a detector, and the demand for detection accuracy is increasing. In the photomultiplier tube, when reflection occurs on the surface of the ceramic insulating member, the reflected light is detected as noise. Therefore, a ceramic insulating member used for a photomultiplier tube is required to exhibit a black color so as to reduce reflection.

  For example, Patent Document 1 discloses an example of a ceramic insulating member for a photomultiplier tube, and describes that Fe, Cr, Co, Mn, Ni, Cu, or the like is used as a colorant for blackening. Yes.

JP-A-8-17388

  In the photomultiplier tube, alkali metal is mainly used for the photocathode. However, like the ceramic insulating member proposed in Patent Document 1, Fe, Ni, Cr, When Mn or the like is contained in the order of several mass% in total, a large amount of alkali metal is adsorbed.

  The content ratio of the alkali metal on the photocathode greatly affects the amount of conversion from light to electrons. As for photomultiplier tubes, a change in detection accuracy is required to be small as detection accuracy increases. For this reason, the ceramic insulating member used in the photomultiplier tube is required to exhibit black color and to have little alkali metal adsorption.

  In addition, the ceramic insulating member has a problem that even if it looks black, the reflectance is increased in the long wavelength region and is detected as noise.

  The present disclosure has been devised in view of such circumstances, and provides a ceramic insulating member that has low alkali metal adsorption and low reflectance over a wide wavelength range.

The ceramic insulating member of the present disclosure is made of an aluminum oxide ceramic including a titanium oxide represented by a composition formula of TiO _2-x (1 ≦ x <2), and is a total of Fe, Ni, Co, Mn, and Cr. Content is 260 mass ppm or less.

  An electron tube of the present disclosure includes a container having an incident window provided with a photocathode, a plurality of electrode bodies positioned in the container, and the ceramic insulating member that is positioned in the container and supports the plurality of electrode bodies. Prepare.

  The ceramic insulating member of the present disclosure has little alkali metal adsorption and low reflectance over a wide wavelength region.

  The electron tube of the present disclosure has high reliability because it has high detection accuracy and a small change in detection accuracy.

It is a schematic diagram which shows the structure of the principal part of the photomultiplier tube which is one Embodiment of the electron tube of this indication. It is a graph which shows the measurement result of the reflectance of the ceramic insulation member of this indication.

  Hereinafter, embodiments of the ceramic insulating member and the electron tube of the present disclosure will be described with reference to the drawings. FIG. 1 is a schematic diagram illustrating a configuration of a main part of a photomultiplier tube 10 which is an embodiment of the electron tube of the present disclosure.

  The photomultiplier tube 10 is a device for converting incident light into electrons, amplifying the electrons at a predetermined amplification rate, and taking them out as an electrical signal. In order to measure the presence or absence of incident light and the amount of light Used.

  The photomultiplier tube 10 includes a container 11 including a photocathode 13 that receives light incident from an incident window 12 and emits photoelectrons, a plurality of electrode bodies 16 located in the container 11, and a plurality of electrodes in the container 11. And a ceramic insulating member 17 that supports the body 11. The photomultiplier tube 10 also includes an electron multiplier 14 that multiplies photoelectrons emitted from the photocathode 13 by a secondary electron emission action, and an anode 15 that extracts the electrons multiplied by the electron multiplier 14. .

  The electron multiplying unit 14 includes box-shaped dynodes 14 a arranged in multiple stages, and the dynodes 14 a at each stage are individually supported by a plate-like electrode body 16. The dynode 14a and the electrode body 16 that supports the dynode 14a are individually electrically connected. The plurality of electrode bodies 16 are sandwiched between ceramic insulating members 17.

  The photocathode 13 is made of a photoelectron emitting material containing an alkali metal, for example, an intermetallic compound composed of Sb and Cs. Alkali metals have a low work function and are difficult to stabilize with a single metal. Therefore, the container 11 is in a state containing alkali metal vapor. In the photomultiplier tube 10, the content ratio of the alkali metal contained in the photocathode 13 and the content ratio of the alkali metal vapor in the container 11 coexist, and these content ratios are balanced at a constant ratio. It is in a state. When this balance fluctuates, the ratio of the amount of electrons emitted from the photocathode 13 with respect to the incident light also fluctuates, which affects the accuracy of detecting the presence or absence of incident light and the measurement accuracy of the light amount. Further, a part of the incident light may pass through the photocathode 13 and enter the container 11. When this incident light is irregularly reflected by the ceramic insulating member 17 or the like and stray light or the like re-irradiated on the photocathode 13 is generated, this stray light becomes noise in light detection.

The ceramic insulating member 17 of this embodiment is made of an aluminum oxide ceramic containing a titanium oxide represented by a composition formula of TiO _2-x (1 ≦ x <2), and is made of Fe, Ni, Co, Mn, and Cr. The total content is 260 mass ppm or less.

Here, the aluminum oxide ceramics refers to ceramics in which the content of aluminum oxide in which Al is converted to Al ₂ O ₃ is 90% by mass or more out of 100% by mass of all components constituting the ceramics. In addition, the titanium oxide having a composition formula of TiO _2-x (1 ≦ x < ₂ ) is obtained by reducing titanium oxide (TiO ₂ ). The crystalline phase of the titanium oxide may be rutile titanium oxide.

  The ceramic insulating member 17 of the present embodiment exhibits a black color having a sufficiently low reflectance with respect to light in a relatively wide wavelength range. Specifically, the lightness index L * in the CIE 1976 L * a * b * color space is 40 or less, and the chromaticness indices a * and b * are 0 or more and 5 or less, and −10 or more and 0 or less, respectively. The value of the brightness index L * and the value of the chromaticness index a * and b * in the CIE 1976 L * a * b * color space can be determined in accordance with JIS Z 8722: 2009. For example, a spectral color difference meter (NF77 manufactured by Nippon Denshoku Industries Co., Ltd. or its successor model) is used, and the measurement conditions may be set to a CIE standard light source D65 and a viewing angle of 2 °.

In the ceramic insulating member 17 of this embodiment, the maximum value R _max of reflectance over a wavelength range of 250 nm to 2500 nm is 24% or less, and ΔR, which is the difference between the maximum value R _max and the minimum value R _min , is 15.3% or less. It is. That is, the ceramic insulating member 17 of the present embodiment has a low reflectance in the wavelength range of 250 nm to 2500 nm, and the dispersion of the wavelength distribution of the light intensity of the reflected light with respect to the irradiated light is small. The ceramic insulating member 17 of the present embodiment has a uniform low reflectance over such a wide wavelength range, and can detect light even under conditions where various types of incident light are incident on the photocathode 13. Accuracy and measurement accuracy are relatively high.

  Although Fe, Ni, Co, Mn, and Cr have a small standard free generation energy and easily adsorb alkali vapor emitted from a member containing an alkali metal, the ceramic insulating member 17 of the present embodiment has Fe, Ni, Co, Mn Since the total content of Cr and Cr is 260 mass ppm or less, there is little adsorption of alkali metal. For this reason, the photomultiplier tube 10 configured using the ceramic insulating member 17 has little adsorption of alkali metal vapor in the atmosphere in the container 11. Moreover, since there is little fluctuation | variation of the alkali metal vapor pressure in the container 11, there is little evaporation amount of the alkali metal from the photocathode 13 with this fluctuation | variation of alkali metal vapor pressure. Thus, when the ceramic insulating member 17 of the present embodiment is used, there is little variation in the content of alkali metal in the atmosphere and on the photocathode 13.

  Thus, the ceramic insulating member 17 of the present embodiment has little alkali metal adsorption and sufficiently low light reflection over a wide wavelength range. The photomultiplier tube 10 configured to include such a ceramic insulating member 17 has high detection accuracy of incident light and measurement accuracy of light quantity, and has little fluctuation in detection accuracy and measurement accuracy.

In the ceramic insulating member 17 of the present embodiment, the content of the oxide of titanium whose composition formula is expressed as TiO _2-x (1 ≦ x <2) is, for example, 100% by mass of the total components constituting the ceramic, It is 0.5 mass% or more and 4 mass% or less. When the content of the oxide of titanium is in the above-described range, it is possible to obtain a black color with a sufficiently low saturation and a low reflectance, and a volume resistivity at room temperature of 10 ¹² Ω · m or more. And electrical insulation. Here, the volume resistivity can be determined in accordance with JIS C 2141: 1992.

  The ceramic insulating member 17 preferably does not contain aluminum titanate. This is because aluminum titanate has a large difference in linear expansion coefficient with respect to aluminum oxide, and minute cracks are likely to occur when heating and cooling are repeated. Whether or not the ceramic insulating member 17 contains aluminum titanate may be collated with an X-ray chart obtained using an X-ray diffractometer (XRD) with a JCPDS card (No. 00-04-1258).

  In the ceramic insulating member 17 of the present embodiment, the total content of Fe, Ni, Co, Mn and Cr is 260 mass ppm or less, that is, the content of Cr alone is 260 mass ppm at the maximum. When Cr is contained in alumina, light having a wavelength of 700 nm or more and less than 780 nm (hereinafter also referred to as short wavelength light) or light having a wavelength of 780 nm or more and less than 1590 nm (hereinafter, long wavelength light) The ceramic insulating member 17 of this embodiment has a low Cr content, and therefore has a low reflectance in the short wavelength region and the long wavelength region.

  If the content of Cr in the ceramic insulating member 17 is 40 mass ppm or less, the reflectance with respect to light in a relatively wide wavelength range is sufficiently low, and reflection of incident light in the ceramic insulating member 17 is suppressed, so that light detection is possible. Increases accuracy.

  Further, if the Fe content in the ceramic insulating member 17 is 100 mass ppm or less, an increase in reflectance due to discoloration can be further suppressed, and therefore the reflectance in the visible light region and the infrared region is further lowered.

  Further, if the Ni content in the ceramic insulating member 17 is 10 ppm by mass or less, the Co content is 5 ppm by mass or less, or the Mn content is 100 ppm by mass or less, the machine is exposed to alkali metal vapor. Changes in mechanical strength and electrical characteristics are reduced.

The ceramic insulating member 17 may contain silicon, calcium, and magnesium oxides in the grain boundary phase that joins the aluminum oxide crystal particles together. Here, the total content of oxides of silicon, calcium and magnesium is, for example, 2% by mass or more and 4% by mass or less, out of 100% by mass of all components constituting the ceramic. Further, when the total content of silicon, calcium and magnesium oxide is 100% by mass, the content of calcium oxide and magnesium oxide is 10% by mass or more and 30% by mass or less, respectively, and the balance is It may be an oxide of silicon. When the content of oxides of silicon, calcium and magnesium is within the above range, the ceramic sintered body has a volume resistivity of 10 ¹² Ω · m or more at room temperature, and the electrical insulation is sufficiently maintained.

  The crystal phase of the titanium oxide in the ceramic insulating member 17 can be identified by XRD, and the value of x may be obtained using a transmission electron microscope (TEM).

In addition, the contents of aluminum, silicon, calcium, magnesium and titanium converted into oxides are determined by using an X-ray fluorescence analyzer (XRF) or an ICP (Inductively Coupled Plasma) emission spectroscopic analyzer (ICP). Is obtained and converted into Al ₂ O ₃ , SiO ₂ , CaO, MgO and TiO _2-x (1 ≦ x <2), respectively. The contents of Fe, Ni, Co, Mn, and Cr may be determined using a glow discharge mass spectrometer (GDMS).

  The ceramic insulating member 17 of the present embodiment may have a portion on the surface facing the container 11 where the average value of the skewness Rsk is 0.04 or more and 0.45 or less. Light that has been transmitted without being converted by the photocathode 13, light that has entered from the outside of the container 11, light that has been reflected inside the container 11, or the like may reach the ceramic insulating member 17. When having such a portion, the reflectance is low. Here, the surface facing the container 11 is, in other words, the surface exposed to the atmosphere in the container 11. The average value of all skewness Rsk on the surface facing the container 11 may be 0.04 or more and 0.45 or less.

  Further, the ceramic insulating member 17 of the present embodiment may have a portion on the surface facing the container 11 where the average value of the kurtosis Rku is 4.1 or more and 6.5 or less. When the ceramic insulating member 17 has such a portion, the reflectance is low. The average value of all kurtosis Rku on the surface facing the container 11 may be 4.1 or more and 6.5 or less.

  Furthermore, the ceramic insulating member 17 of the present embodiment may have a portion on the surface facing the container 11 where the average value of the arithmetic average roughness Ra is not less than 1 μm and not more than 2 μm. When the ceramic insulating member 17 has such a portion, the reflectance is low. In addition, the average value of all arithmetic average roughness Ra of the surface facing the container 11 may be 1 μm or more and 2 μm or less.

  The kurtosis Rku, the skewness Rsk, and the arithmetic average roughness Ra can be determined using, for example, a laser microscope (manufactured by Keyence Corporation (VK-9510)) in accordance with JIS B 0601: 2001. The measurement conditions are as follows: measurement mode is color depth, measurement magnification is 400 times, measurement range is 698 μm × 522 μm, measurement pitch is 0.05 μm, λs contour curve filter is 2.5 μm, λc contour curve filter is 0.08 mm, The average value of the measurement values obtained from the eight measurement ranges may be the average value of the skewness Rsk, the kurtosis Rku, and the arithmetic average roughness Ra.

  Since the ceramic insulating member 17 of the present embodiment described above has a low reflectance in the visible light region and the infrared region, for example, as a suction nozzle for sucking an electrode clamping member or an electronic component disposed in the electron tube. Can be used.

  Next, an example of the manufacturing method of the ceramic insulating member of this embodiment is demonstrated.

  First, powders of aluminum oxide, silicon oxide, calcium carbonate, magnesium hydroxide and titanium oxide are prepared.

  The total content of the powders of calcium carbonate, magnesium hydroxide and silicon oxide is, for example, 6.5% by mass or more and 12.9% by mass or less, out of the total 100% by mass of the powder. And the content of the powder of calcium carbonate, magnesium hydroxide and silicon oxide is 17.8 mass% or more and 53.4 mass% or less among the total 100 mass% of these powders. The content of magnesium hydroxide powder is 14.4 mass% or more and 43.2 mass% or less, and the balance is silicon oxide powder.

  The content of the titanium oxide powder is, for example, 0.5% by mass or more and 4% by mass or less of the total 100% by mass of each powder of aluminum oxide, silicon oxide, calcium carbonate, magnesium hydroxide, and titanium oxide, The balance is aluminum oxide powder.

  These powders are wet-mixed and pulverized by a pulverizer such as a barrel mill, a rotary mill, a vibration mill, a bead mill, an agitator mill, an atomizer, or an attritor to obtain a slurry. In the above pulverization, the solvent, an organic binder such as polyvinyl alcohol (PVA) of 1 part by weight to 1.5 parts by weight with respect to 100 parts by weight of the solvent, and 0.1 parts by weight with respect to 100 parts by weight of the solvent. More than 0.5 parts by weight and less than 0.5 parts by weight of the dispersant is added to the pulverizer. Next, the obtained slurry is demagnetized and then spray-dried to obtain granules. The ferromagnetic metals Fe, Ni and Co are removed by the demagnetization process.

Further, the contents of Fe, Ni, Co, Mn and Cr in the ceramic insulating member are affected by the wear of the stainless steel member used in the pulverizer. For example, a stainless steel member that wears out over a long period of time can be replaced with a titanium component that easily forms a passive film on the surface, or a titanium-based film such as TiN, TiCN, TiC, TiAlN, TiAlCN, or TiAlO, or amorphous. The surface of the stainless steel member may be coated with hard carbon (DLC). In addition to the demagnetization treatment, a ceramic insulating member having a total content of Fe, Ni, Co, Mn, and Cr of 260 mass ppm or less can be obtained by replacing or covering the stainless steel member.

  Then, the granules are formed into a molded body by a dry pressure molding method or molded by a cold isostatic pressing method (CIP) and then subjected to cutting to obtain a molded body. Then, a sintered body can be obtained by firing the obtained compact in an air (oxidation) atmosphere at a temperature of 1500 ° C. or higher and 1700 ° C. or lower for a predetermined time.

  In addition, you may grind after baking. Moreover, it is good also as a predetermined | prescribed surface property by performing grinding | polishing which adjusted the abrasive | polishing material, the frequency, and grinding | polishing time using a vibration barrel grinder as needed.

  Then, using the sintered body obtained by the above-described method as a reducing atmosphere, for example, in a mixed gas in which the ratio of nitrogen: hydrogen is 87 to 90% by volume: 10 to 13% by volume, the temperature is 1300 ° C. or higher and 1400 ° C. or lower. The ceramic insulating member of the present embodiment can be obtained by maintaining the temperature at 1 to 2 hours.

  The ceramic insulating member obtained by the manufacturing method described above has low reflectance in the visible light region and infrared region, and also has little adsorption of alkali metal, so that the member or chip-like member that sandwiches the electrode disposed in the electron tube It can be used for a suction nozzle used in an electronic component mounting machine for mounting electronic components on a circuit board.

  First, powders of aluminum oxide, silicon oxide, calcium carbonate, magnesium hydroxide and titanium oxide were prepared.

  The content of each powder of aluminum oxide, silicon oxide, calcium carbonate, magnesium hydroxide, and titanium oxide was adjusted so that the components constituting the sintered body, which is a ceramic insulating member, had the values shown in Table 1.

  These powders were wet-mixed with a barrel mill and pulverized to obtain a slurry. In crushing, 1.25 parts by mass of polyvinyl alcohol (PVA) with respect to 100 parts by mass of the solvent and the solvent, and 0.3 parts by mass of the dispersant with respect to 100 parts by mass of the solvent were also put into the pulverizer. . Next, after adjusting the obtained slurry so that the total content of Fe, Ni, Co, Mn and Cr in the ceramic insulating member becomes the value shown in Table 1 by demagnetization treatment, spray drying, Granules were obtained. The stainless steel member used in the pulverizer was preliminarily coated with a TiN film, and then the powder was pulverized.

  And it shape | molded by the cold isostatic pressing method (CIP) using the granule, Then, cutting was given and the molded object was obtained. Thereafter, the obtained molded body was held in the atmosphere (oxidation) atmosphere at a temperature of 1570 ° C. for a predetermined time to obtain a sintered body. Next, the surface of the sintered body was polished using a vibration barrel polishing machine.

  And the sintered compact obtained by the method mentioned above is hold | maintained at the temperature of 1350 degreeC for 1 hour 30 minutes in reducing atmosphere (The ratio of nitrogen: hydrogen is 88.5 volume%: 11.5 volume%). Sample no. 1-4 were obtained.

Each sample obtained was identified using XRD. In addition, the value of _x in TiO _2-x was determined using a transmission electron microscope (TEM). In addition, the content of the elements constituting each sample was determined using XRF and converted to the identified components. Furthermore, the contents of trace components Fe, Ni, Co, Mn and Cr were determined using a glow discharge mass spectrometer (GDMS). These results are shown in Table 1. In addition, as a component not shown in Table 1, inevitable impurities are included.

In addition, for each sample, the reflectance of the region at a wavelength of 250 nm to 2500 nm is obtained using an ultraviolet-visible near-infrared spectrophotometer (manufactured by JASCO Corporation, V-670), and the measured values are shown as graphs It was shown in 2. Further, ΔR was calculated from the minimum value R _min and the maximum value R _max of the reflectance in the above region of each sample. Table 1 shows the minimum value R _min , the maximum value R _max and ΔR of the reflectance.

  Here, the integrating sphere unit used for the reflectance measurement is ISN-723, the reference light source is a deuterium lamp in the region with a wavelength of 250 nm to 360 nm, and a halogen lamp in the region with a wavelength of 360 nm to 2500 nm. The mode was total reflectance, the data acquisition interval was 1.0 nm, the UV / Vis bandwidth was 5.0 nm, and the NIR bandwidth was 20.0 nm.

  Further, in order to examine the amount of adsorption of alkali vapor of each sample, each sample was accommodated in the container, and then K, Rb, and Cs were sealed as alkali vapor. Thereafter, the inside of the container was vacuumed and then sealed.

  Each sample was removed from the container, and the amount of alkali vapor adsorbed on the surface of each sample was measured by XRF. From sample 4, sample no. 1 to 3 were all found to have a small amount of alkali vapor adsorption.

As shown in Table 1 and FIG. 1-3 are sample numbers. The values of R _max and ΔR were smaller than 4. From this result, it consists of the aluminum oxide ceramics containing the oxide of titanium shown by a composition formula as TiO _2-x (1 ≦ x <2), and the total content of Fe, Ni, Co, Mn and Cr is 260. It was found that when the mass ppm or less, the reflectance is low in the wavelength range of 250 nm to 2500 nm, and the variation in the wavelength distribution of the light intensity of the reflected light with respect to the irradiated light is small.

  In particular, sample no. No. 1 is more suitable for use as described above because the difference ΔR in reflectance between the regions is 6.2%.

  As mentioned above, although the Example of this invention was described, unless it exceeds the summary of this invention, it is not limited to the said Example.

10 Photomultiplier tubes (electron tubes)
11 Container 12 Incident Window 13 Photocathode 14 Electron Multiplier 15 Anode 16 Electrode 17 Ceramic Insulating Member

Claims (4)

It consists of an aluminum oxide ceramic containing an oxide of titanium whose composition formula is shown as TiO _2-x (1 ≦ x <2),
A ceramic insulating member having a total content of Fe, Ni, Co, Mn and Cr of 260 mass ppm or less. A container having an entrance window with a photocathode;
A plurality of electrode bodies located in the container;
An electron tube comprising: the ceramic insulating member according to claim 1, which is located in the container and sandwiches the plurality of electrode bodies. The ceramic insulating member is
3. The electron tube according to claim 2, wherein a portion having an average skewness Rsk of 0.04 or more and 0.45 or less is provided on a surface facing the container. The ceramic insulating member is
4. The electron tube according to claim 2, wherein a portion having an average value of Kurtosis Rku of 4.1 or more and 6.5 or less is provided on a surface facing the container.