JP4521511B2 - Temperature fixed point cell, temperature fixed point device, and thermometer calibration method - Google Patents
Temperature fixed point cell, temperature fixed point device, and thermometer calibration method Download PDFInfo
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- JP4521511B2 JP4521511B2 JP2004131756A JP2004131756A JP4521511B2 JP 4521511 B2 JP4521511 B2 JP 4521511B2 JP 2004131756 A JP2004131756 A JP 2004131756A JP 2004131756 A JP2004131756 A JP 2004131756A JP 4521511 B2 JP4521511 B2 JP 4521511B2
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N11/00—Monitoring or diagnostic devices for exhaust-gas treatment apparatus, e.g. for catalytic activity
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N13/00—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00
- F01N13/18—Construction facilitating manufacture, assembly, or disassembly
- F01N13/1805—Fixing exhaust manifolds, exhaust pipes or pipe sections to each other, to engine or to vehicle body
- F01N13/1811—Fixing exhaust manifolds, exhaust pipes or pipe sections to each other, to engine or to vehicle body with means permitting relative movement, e.g. compensation of thermal expansion or vibration
- F01N13/1816—Fixing exhaust manifolds, exhaust pipes or pipe sections to each other, to engine or to vehicle body with means permitting relative movement, e.g. compensation of thermal expansion or vibration the pipe sections being joined together by flexible tubular elements only, e.g. using bellows or strip-wound pipes
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/10—Internal combustion engine [ICE] based vehicles
- Y02T10/40—Engine management systems
Description
本発明は、例えば放射温度計や熱電対等の高温域で使用される温度計の校正に用いる温度定点セル、温度定点装置および温度計校正方法に関する。 The present invention relates to a temperature fixed point cell, a temperature fixed point device, and a thermometer calibration method used for calibration of a thermometer used in a high temperature range such as a radiation thermometer and a thermocouple.
温度計を校正する際、常温域以上では金属の凝固点もしくは融点が温度の定義定点として採用され、その実現方法として温度定点るつぼが用いられる。これらは通常、黒鉛製のるつぼを用い、その中に定点物質として純金属を鋳込んだものであり、その内部の温度を温度計で測定し、温度定点るつぼを温度可変の炉の内部に置き環境温度を昇温・降温させたときのるつぼの温度変化を観測、定点物質の液相・固相が共存する状態では融解の潜熱により温度変化がなくなることを利用して温度計の校正を行うものである（（社）日本電気計測器工業界編「新編温度計の正しい使い方」、第７章、日本工業出版社（１９９７）参照）。 When calibrating a thermometer, the freezing point or melting point of the metal is adopted as a temperature-defined fixed point above the normal temperature range, and a temperature fixed point crucible is used as a method for realizing it. These are usually graphite crucibles in which pure metal is cast as a fixed point material, the temperature inside is measured with a thermometer, and the temperature fixed point crucible is placed inside a temperature variable furnace. Observe the temperature change of the crucible when the environmental temperature is raised or lowered, and calibrate the thermometer using the fact that the temperature change disappears due to the latent heat of melting when the liquid phase and solid phase of the fixed point substance coexist (Refer to “Establishment of the New Thermometer”, Chapter 7, Nippon Kogyo Publishing Co., Ltd. (1997)).
温度定点の最高温度は、純金属を定点物質として用いる場合、１０８５℃の銅点であり、銅点より高温域では外挿により目盛りが定義されている。銅点以上の温度域での目盛りの維持には銅点以下で定点校正された放射温度計を利用するか、リボン電球と呼ばれるタングステンリボンをフィラメントとする電球の放射輝度と電流の特性に目盛りを移して行われている。 The maximum temperature of the temperature fixed point is a copper point of 1085 ° C. when pure metal is used as the fixed point substance, and the scale is defined by extrapolation in a region higher than the copper point. To maintain the scale in the temperature range above the copper point, use a radiant thermometer calibrated at a fixed point below the copper point, or calibrate the radiance and current characteristics of a light bulb with a tungsten ribbon called a ribbon bulb. Has been done.
このようなことから特許文献１には、炭素を成分とするるつぼと、このるつぼ内に封入され、炭素と金属との共晶組織の定点物質とからなり、銅点を超える温度域で定点を実現することが可能な温度定点セルが開示されている。
また、特許文献２には炭素を成分とするるつぼと、このるつぼ内に封入され、炭化物と炭素の共晶組織、または炭素固溶体と炭素の共晶組織の定点物質とからなり、２５００℃を超える温度域まで定点温度域を拡張することが可能な温度定点セルが開示されている。
しかしながら、前記特許文献１，２の温度定点るつぼにおいて、温度計校正の目的のためにそのるつぼを温度可変電気炉の内部に置き、環境温度を昇温・降温させると、その定点物質が膨張・収縮することによりるつぼにストレスが加わって亀裂を生じる虞があった。この亀裂発生は、共晶組織の一成分がるつぼと同じ炭素材料であるために共晶組織の他の成分（例えば金属）がるつぼ内面に密着し易くなることも関連している。
Patent Document 2 includes a crucible containing carbon as a component, and a fixed-point substance of a carbide and carbon eutectic structure or a carbon solid solution and carbon eutectic structure enclosed in the crucible, and exceeds 2500 ° C. A temperature fixed point cell capable of extending a fixed point temperature range to a temperature range is disclosed.
However, in the temperature fixed point crucibles of Patent Documents 1 and 2, if the crucible is placed inside the temperature variable electric furnace for the purpose of thermometer calibration, and the environmental temperature is raised and lowered, the fixed point substance expands and The shrinkage may cause stress on the crucible and cause cracks. This crack generation is also related to the fact that one component of the eutectic structure is the same carbon material as the crucible, so that other components (for example, metal) of the eutectic structure easily adhere to the inner surface of the crucible.
本発明は、１１００℃から３０００℃を超える温度域で定点を実現することが可能で、かつ使用時でのるつぼの亀裂発生を防止することが可能な温度定点セルを提供するものである。
本発明は、前記特性の温度定点セルを備えた温度定点装置を提供するものである。
本発明は、放射温度計、熱電対、その他の１１００℃から３０００℃を超える高温域で使用されるあらゆる温度計の校正の高精度化を達成することが可能な温度計校正方法を提供するものである。
The present invention provides a temperature fixed point cell capable of realizing a fixed point in a temperature range exceeding 1100 ° C. to 3000 ° C. and capable of preventing the crucible from cracking during use.
The present invention provides a temperature fixed point device including a temperature fixed point cell having the above characteristics.
The present invention provides a thermometer calibration method capable of achieving high accuracy in calibration of radiation thermometers, thermocouples, and other thermometers used in a high temperature range exceeding 1100 ° C. to 3000 ° C. It is.
本発明によると、炭素を成分とするるつぼと、このるつぼ内に封入される定点物質とを含む温度定点セルであって、
前記定点物質は、金属または金属炭化物と炭素との共晶が存在された、炭素粉末を含む多孔質体からなることを特徴とする温度定点セルが提供される。
また本発明によると、炭素を成分とするるつぼと、このるつぼ内に封入される定点物質とを含む温度定点セルであって、
前記定点物質は、（ａ）金属または金属炭化物と炭素との共晶と（ｂ）炭素粉末とからなる顆粒であることを特徴とする温度定点セルが提供される。
さらに本発明によると、前記２つの温度定点セルのうちいずれか一方の温度定点セルと、
前記温度定点セルが内部に設置され、その温度定点セルの周囲温度を上昇または下降させる炉と
を具備することを特徴とする温度定点装置が提供される。
さらに本発明によると、前記２つの温度定点セルのうちいずれか一方の温度定点セルの周囲温度を上昇または下降せしめ、その時の前記温度定点セルの温度変化を温度計にて測定し、測定された温度変化状態から前記温度計を校正することを特徴とする温度計校正方法が提供される。
According to the present invention, a temperature fixed point cell including a crucible containing carbon as a component and a fixed point substance enclosed in the crucible,
A temperature fixed point cell is provided, wherein the fixed point substance is made of a porous body containing carbon powder in which a eutectic of metal or metal carbide and carbon is present.
Further, according to the present invention, there is provided a temperature fixed point cell including a crucible containing carbon as a component and a fixed point substance enclosed in the crucible,
A temperature fixed point cell is provided, wherein the fixed point substance is a granule composed of (a) a eutectic of metal or metal carbide and carbon and (b) carbon powder.
Furthermore, according to the present invention, either one of the two temperature fixed point cells, the temperature fixed point cell,
There is provided a temperature fixed point device characterized in that the temperature fixed point cell is installed inside and a furnace for raising or lowering the ambient temperature of the temperature fixed point cell.
Further, according to the present invention, the ambient temperature of either one of the two temperature fixed point cells is raised or lowered, and the temperature change of the temperature fixed point cell at that time is measured with a thermometer, and measured. A thermometer calibration method is provided, wherein the thermometer is calibrated from a temperature change state.
本発明に係る温度定点セルは、１１００℃から３０００℃を超える温度域で定点を実現することが可能で、かつ使用時でのるつぼの亀裂発生を防止することが可能になり、高性能、長寿命化を達成できる。
本発明に係る温度定点装置は、前記特性の温度定点セルを備え、高温域での放射温度計、熱電対、その他の温度計の校正が内挿で行え、高精度で長寿命の温度定点装置を提供することができる。
The temperature fixed point cell according to the present invention can realize a fixed point in a temperature range exceeding 1100 ° C. to 3000 ° C., and can prevent crucible cracks during use. Life expectancy can be achieved.
A temperature fixed point device according to the present invention includes a temperature fixed point cell having the above characteristics, and can calibrate a radiation thermometer, thermocouple, and other thermometers in a high temperature range by interpolation, and has a high accuracy and a long life. Can be provided.
本発明に係る温度計校正方法は、前記特性の温度定点セルを用いることによって、従来における温度計の校正手段の欠如や目盛りの不確かさのために十分な精度が得られなかった高温域での温度校正精度を向上できると共に、その校正操作を長期間にわたって安定的に実施できる。 The thermometer calibration method according to the present invention uses a temperature fixed point cell having the above characteristics, so that sufficient accuracy cannot be obtained due to lack of conventional thermometer calibration means and uncertainty of scale. The temperature calibration accuracy can be improved and the calibration operation can be stably performed over a long period of time.
以下、本発明に係る温度定点セル、温度定点装置および温度校正方法を詳細に説明する。
（第１実施形態）
図１は、この第１実施形態に係る温度定点セルを示す断面図である。
Hereinafter, a temperature fixed point cell, a temperature fixed point device, and a temperature calibration method according to the present invention will be described in detail.
(First embodiment)
FIG. 1 is a cross-sectional view showing a temperature fixed point cell according to the first embodiment.
温度定点セル１は、炭素を成分とする、例えば黒鉛からなるるつぼ２を備えている。このるつぼ２は、片封じ円筒状のるつぼ本体３と、この本体３の片封じ部から内部に向かって突出させることにより形成された空洞４と、前記本体３の開口部に気密に取り付けられた黒鉛からなる円板状蓋体５とから構成されている。定点物質６は、金属（または金属炭化物）と炭素との共晶が存在された、炭素粉末を含む組成を有し、前記るつぼ２内に前記黒体空洞４が位置する突起部を覆うように封入された外形が円柱状の多孔質体からなる。この多孔質体６は、金属（または金属炭化物）／炭素の共晶の融解・凝固点温度を定点として用いる。前記多孔質体６の外周面とるつぼ１の内面の間には、所望の隙間が形成されている。なお、多孔質体６上面とるつぼ１内面間には黒鉛製のスペーサ７が介在されている。 The temperature fixed point cell 1 includes a crucible 2 made of carbon, for example, made of graphite. The crucible 2 is airtightly attached to a crucible main body 3 having a single-sealed cylindrical shape, a cavity 4 formed by projecting from a single-sealed portion of the main body 3 toward the inside, and an opening of the main body 3. It is comprised from the disk-shaped cover body 5 which consists of graphite. The fixed-point material 6 has a composition containing carbon powder in which a eutectic of metal (or metal carbide) and carbon is present, and covers the protrusion where the black body cavity 4 is located in the crucible 2. The enclosed outer shape is a cylindrical porous body. The porous body 6 uses the melting / freezing point temperature of the eutectic of metal (or metal carbide) / carbon as a fixed point. A desired gap is formed between the outer peripheral surface of the porous body 6 and the inner surface of the crucible 1. A graphite spacer 7 is interposed between the upper surface of the porous body 6 and the inner surface of the crucible 1.
前記定点物質を構成する金属としては、銅点より融点が高い炭素共晶を形成するものであればよく、例えば鉄、コバルト、ニッケル、パラジウム、ロジウム、白金、ルテニウム、イリジウム、レニウム、オスミウム等を挙げることができる。 The metal constituting the fixed-point substance may be any metal that forms a carbon eutectic with a melting point higher than that of the copper point, such as iron, cobalt, nickel, palladium, rhodium, platinum, ruthenium, iridium, rhenium, and osmium. Can be mentioned.
前記定点物質を構成する金属炭化物としては、銅点より融点が高い炭素共晶を形成するものであればよく、例えばホウ素、モリブデン、バナジウム、チタン、ジコニウム、ハフニウム、ニオブ、タングステン、または希土類元素の炭化物を挙げることができる。
前述した温度定点セルは、例えば次のような方法により製造される。
まず、高純度の金属（または金属炭化物）の粉末と高純度の黒鉛粉末とを金属（または金属炭化物）／炭素の共晶組成より黒鉛粉末が多くなるように混合し、この混合粉末を黒体空洞を有する黒鉛製のるつぼ本体内に充填する。つづいて、このるつぼ本体の開口部を開放した状態で縦型電気炉内に設置し、前記炉内をアルゴンで置換してアルゴン雰囲気にするか、または炉内を真空引きして高真空状態にした後、前記共晶の融点より低い温度まで加熱して、その温度を所望時間維持することにより金属が焼結される。ひきつづき、前記共晶の融点より高い温度に加熱することにより金属が溶融し、共存する面状黒鉛粉末で覆われて金属が島状態で分離される。この後、電気炉のヒータへの通電を切り、室温まで冷却することにより、前記金属が凝固する過程で炭素粉末が共存された状態で金属と炭素との共晶が生成される。このため、金属と炭素との共晶が存在された、炭素粉末を含む組成を有する外形が円柱状の多孔質体が作られる。この多孔質体は、外周がるつぼ本体内面との間に所望の隙間があけられ、かつ上端が本体の開口端より下方に位置される。最後に、多孔質体の上端に例えば黒鉛からなる円板状のスペーサを重ね、黒鉛製の蓋体をるつぼ本体の開口端に固定して定点物質である前記多孔質体を気密に封止することにより温度定点セルが製造される。
このような温度定点セルの製造において、原料である混合粉末の一回の充填（鋳込み）、加熱によって定点物質である多孔質体を得ること可能になり、製造コストを低減できる。
すなわち、前述した特許文献１，２の発明ではるつぼ内に共晶組成の定点物質を封入する場合、粉末から融解したときに体積減少が大きい、つまり充填率が著しく減少するため、定点物質の完全な充填状態を得るには１０回程度の鋳込み操作を繰り返す必要がある。このため、温度定点セルの製造コストが高くなる。
これに対し、第１実施形態では金属（または金属炭化物）と炭素との共晶が存在された、炭素粉末を含む組成の多孔質体をるつぼ内に所望の隙間をあけて封入する構造であるため、１回の混合粉末のるつぼ内への充填、加熱の操作で得られ、かつ金属（金属炭化物）の量を低減できる。その結果、低コストで温度定点セルを製造することが可能になる。
次に、前述した温度定点セルを備えた温度定点装置を図２を参照して説明する。
温度定点装置は、縦型可変電気炉２１を有する。この可変電気炉２１は、円筒状の断熱材２２と、この断熱材２２の内部に配置された円筒状に捲回したヒータエレメント２３を備えている。このヒータエレメント２３は、図示しない制御器を有するヒータ電源に接続されている。
上端にフランジ２４を有するアルミナ製の有底筒状炉心管２５は、前記円筒状の断熱材２２の上端側からその外周面が前記ヒータエレメント２３に囲まれるように挿入、支持されている。この炉心管２５内には、前述した図１に示す温度定点セル１がその空洞４が上方に向くように装填されている。
The metal carbide constituting the fixed point material may be any carbon carbide that has a melting point higher than the copper point, such as boron, molybdenum, vanadium, titanium, ziconium, hafnium, niobium, tungsten, or a rare earth element. Carbides can be mentioned.
The above-mentioned temperature fixed point cell is manufactured by the following method, for example.
First, high-purity metal (or metal carbide) powder and high-purity graphite powder are mixed so that the graphite powder is larger than the eutectic composition of metal (or metal carbide) / carbon, and this mixed powder is a black body. The graphite crucible body having a cavity is filled. Next, the crucible body is opened in a vertical electric furnace with the opening opened, and the inside of the furnace is replaced with argon to create an argon atmosphere, or the furnace is evacuated to a high vacuum state. After that, the metal is sintered by heating to a temperature lower than the melting point of the eutectic and maintaining the temperature for a desired time. Subsequently, the metal is melted by heating to a temperature higher than the melting point of the eutectic, and is covered with the coexisting planar graphite powder to separate the metal in an island state. Thereafter, by turning off the electric current to the heater of the electric furnace and cooling to room temperature, a eutectic of metal and carbon is produced in the state where the carbon powder coexists in the process of solidifying the metal. For this reason, a porous body having a cylindrical outer shape having a composition containing carbon powder in which a eutectic of metal and carbon is present. This porous body has a desired gap between the outer periphery and the inner surface of the crucible body, and the upper end is positioned below the open end of the body. Finally, a disk-shaped spacer made of, for example, graphite is stacked on the upper end of the porous body, and a graphite lid is fixed to the opening end of the crucible body to hermetically seal the porous body, which is a fixed point substance. Thus, the temperature fixed point cell is manufactured.
In the manufacture of such a temperature fixed point cell, it becomes possible to obtain a porous body as a fixed point substance by one filling (casting) and heating of the mixed powder as a raw material, and the manufacturing cost can be reduced.
That is, in the inventions of Patent Documents 1 and 2 described above, when a fixed-point substance having a eutectic composition is enclosed in a crucible, the volume reduction is large when melted from the powder, that is, the filling rate is significantly reduced. It is necessary to repeat the casting operation about 10 times to obtain a proper filling state. For this reason, the manufacturing cost of a temperature fixed point cell becomes high.
In contrast, the first embodiment has a structure in which a porous body having a composition containing carbon powder in which a eutectic of metal (or metal carbide) and carbon is present is enclosed in a crucible with a desired gap. Therefore, it is obtained by filling and heating the mixed powder into the crucible once, and the amount of metal (metal carbide) can be reduced. As a result, a temperature fixed point cell can be manufactured at low cost.
Next, the temperature fixed point apparatus provided with the temperature fixed point cell mentioned above is demonstrated with reference to FIG.
The temperature fixing device has a vertical variable electric furnace 21. The variable electric furnace 21 includes a cylindrical heat insulating material 22 and a heater element 23 wound in a cylindrical shape and disposed inside the heat insulating material 22. The heater element 23 is connected to a heater power source having a controller (not shown).
A bottomed cylindrical core tube 25 made of alumina having a flange 24 at the upper end is inserted and supported from the upper end side of the cylindrical heat insulating material 22 so that its outer peripheral surface is surrounded by the heater element 23. In the furnace tube 25, the temperature fixed point cell 1 shown in FIG. 1 is loaded so that the cavity 4 faces upward.
アルミナ製保護管２６は、前記炉心管２５のフランジ２４中心を貫通して前記温度定点セル１の空洞４内に挿入されている。アルゴンのような希ガスを導入するためのガス導入管２７は、前記炉心管２５のフランジ２４を貫通してその炉心管２５内に挿入されている。排気管２８は、一端が前記炉心管２５のフランジ２４に連結され、他端が図示しない真空ポンプのような排気部材に連結されている。
モニタ用熱電対２９は、前記断熱材２２の下端側からその先端が前記炉心管２５の底部に近接するように挿入されている。このモニタ用熱電対２９は、前記ヒータ電源の制御器に接続され、温度測定結果が前記制御器に入力される。温度測定結果が制御器に入力されると、その制御器から前記ヒータ電源に制御信号が出力されて、前記ヒータエレメント２３の発熱温度を制御する。
このような図２に示す構成の温度定点装置による定点校正方法を説明する。
まず、温度定点セル１の空洞４に挿置された保護管２６内に被校正熱電対３０を挿入する。図示しない真空ポンプを作動して炉心管２５内の空気を排気管２８を通して排気すると共に、例えばアルゴンガスをガス導入管２８を通して前記炉心管２５内に導入することにより炉心管２５内をアルゴン雰囲気にする。このように炉心管２５内をアルゴン雰囲気にすることにより、その炉心管２５内の装填された温度定点セル１の黒鉛るつぼの酸化焼失を防ぐと共に、同セルに封入された定点物質の酸化を防止する。
前記炉心管２５内がアルゴンで十分に置換された後、図示しないヒータ電源からヒータエレメント２３に通電して所望の速度で前記断熱材１の炉心管２５内を昇温する。炉心管２５の温度がその内部に装填された図１に示す温度定点セル１の定点物質である多孔質体６に存在する金属（または金属炭化物）／炭素の共晶の融点近傍に達すると、その融点近傍で温度を上下動させる。このとき、前記金属（または金属炭化物）／炭素の共晶が融点を超えると、多孔質体６を構成する炭素（黒鉛）が僅かに溶出するが、再度温度を下げると余分な黒鉛は多孔質体６の面状黒鉛粉末に析出するため、凝固点に至るときには共晶の組成比に戻る。そのため、再現性の良い溶解・凝固プラトーが観測される。共晶は、多孔質体６の一方の成分およびるつぼ材料と同じ黒鉛と純金属とかなる組成を有するため、本質的に前記黒鉛が不純物となり得ず、凝固点降下は生じない。
The alumina protective tube 26 passes through the center of the flange 24 of the furnace core tube 25 and is inserted into the cavity 4 of the temperature fixed point cell 1. A gas introduction tube 27 for introducing a rare gas such as argon passes through the flange 24 of the core tube 25 and is inserted into the core tube 25. The exhaust pipe 28 has one end connected to the flange 24 of the core tube 25 and the other end connected to an exhaust member such as a vacuum pump (not shown).
The monitoring thermocouple 29 is inserted from the lower end side of the heat insulating material 22 so that the tip thereof is close to the bottom of the core tube 25. This monitoring thermocouple 29 is connected to the controller of the heater power supply, and the temperature measurement result is input to the controller. When the temperature measurement result is input to the controller, a control signal is output from the controller to the heater power supply to control the heat generation temperature of the heater element 23.
A fixed point calibration method using the temperature fixed point apparatus having the configuration shown in FIG. 2 will be described.
First, the thermocouple 30 to be calibrated is inserted into the protective tube 26 inserted in the cavity 4 of the temperature fixed point cell 1. A vacuum pump (not shown) is operated to exhaust air in the core tube 25 through the exhaust tube 28, and, for example, argon gas is introduced into the core tube 25 through the gas introduction tube 28 to bring the inside of the core tube 25 into an argon atmosphere. To do. By making the inside of the core tube 25 in an argon atmosphere in this way, the graphite crucible of the temperature fixed point cell 1 loaded in the core tube 25 is prevented from being burned out by oxidation, and the fixed point material enclosed in the cell is prevented from being oxidized. To do.
After the inside of the core tube 25 is sufficiently replaced with argon, the heater element 23 is energized from a heater power source (not shown) to raise the temperature inside the core tube 25 of the heat insulating material 1 at a desired speed. When the temperature of the core tube 25 reaches the melting point of the metal (or metal carbide) / carbon eutectic present in the porous body 6 which is the fixed point material of the temperature fixed point cell 1 shown in FIG. The temperature is moved up and down in the vicinity of the melting point. At this time, when the metal (or metal carbide) / carbon eutectic exceeds the melting point, carbon (graphite) constituting the porous body 6 is slightly eluted, but when the temperature is lowered again, the excess graphite becomes porous. Since it precipitates in the planar graphite powder of the body 6, it returns to the eutectic composition ratio when reaching the freezing point. Therefore, a reproducible dissolution / coagulation plateau is observed. Since the eutectic has the same composition of graphite and pure metal as one component of the porous body 6 and the crucible material, the graphite cannot essentially be an impurity, and freezing point depression does not occur.
このような温度定点セル１の定点物質である多孔質体６に存在する金属（または金属炭化物）／炭素の共晶の溶融・凝固において、温度定点セル１の空洞４に保護管２６が挿置され、この保護管２６内に挿入された被校正熱電対３０で温度定点セル１の温度を測定する。この被校正熱電対３０の出力と温度定点セル１の共晶の融点を対応させることにより校正を行う。
したがって、熱電対の定点校正において、前記多孔質体に存在する金属（または金属炭化物）／炭素の共晶は融点が銅より高いために１１００℃から３０００℃を超える温度域で定点の校正を実現できる。
また、前記温度定点セル１において多孔体６は図１に示すように黒鉛るつぼ２の内面に対して所望の隙間をあけて封入されているため、定点校正後の冷却過程でのるつぼ２と定点物質６との間の熱膨張差に起因するるつぼ２へのストレス発生も回避できる。したがって、るつぼ２の亀裂発生を防止して長寿命化を達成できる。
なお、第１実施形態において被校正温度計としては熱電対を用いたが、この他に抵抗温度計、ファイバー温度計等の高温接触温度計を用いることができる。
（第２実施形態）
図３は、この第２実施形態に係る温度定点セルを示す断面図である。なお、図３において図１と同様な部材は同符号を付して説明を省略する。
温度定点セル１は、るつぼ２を構成する円筒状のるつぼ本体３内面と多孔質体６の隙間に例えば複数枚の黒鉛ペーパを積層した円筒状の黒鉛支持部材８が介挿され、るつぼ２を構成する黒鉛からなる円板状蓋体５と多孔質体６の隙間に例えば複数枚の黒鉛ペーパを積層した円板状支持体９を介挿した構造を有する。
前記定点物質を構成する金属、金属炭化物は、第１実施形態で説明したものと同様なものが用いられる。
前記支持体は、黒鉛ペーパの積層物の他に、単一の黒鉛体から形成してもよい。
前述した温度定点セルは、例えば次のような方法により製造される。
まず、高純度の金属（または金属炭化物）の粉末と高純度の黒鉛粉末とを金属（または金属炭化物）／炭素の共晶組成より黒鉛粉末が多くなるように混合し、この混合粉末を黒体空洞を有する黒鉛製のるつぼ本体内に充填する。つづいて、この本体の開口部を開放した状態で縦型電気炉内に設置し、前記炉内をアルゴンで置換してアルゴン雰囲気にするか、または炉内を真空引きして高真空状態にした後、前記共晶の融点より低い温度まで加熱して、その温度を所望時間維持することにより金属が焼結される。このとき、金属焼結物を含む黒鉛粉末の混合体はるつぼ本体内にその内面との間に所望の隙間をあけて生成される。電気炉のヒータへの通電を切り、室温まで冷却した後、るつぼ本体と混合体の隙間に例えば複数枚の黒鉛ペーパを積層した円筒状の黒鉛支持部材を介在し、混合体の上端に複数枚の黒鉛ペーパを積層した円板状の黒鉛支持部材を重ね、黒鉛製の蓋体を本体の開口端に固定する。再度、電気炉のヒータへの通電を行って前記共晶の融点より高い温度に加熱することにより前記混合体の金属が溶融し、共存する面状黒鉛粉末で覆われて金属が島状態で分離される。ひきつづき、電気炉のヒータへの通電を切り、室温まで冷却するにより前記金属が凝固する過程で炭素粉末が共存された状態で金属と炭素との共晶が生成される。このため、金属（または金属炭化物）と炭素との共晶が存在された、炭素粉末を含む組成を有する定点物質である外形が円柱状の多孔質体が前記黒鉛支持部材の内部に作られ、温度定点セルが製造される。
このような温度定点セルの製造において、原料である混合粉末の一回の充填（鋳込み）、加熱によって定点物質である多孔質体を得ること可能になり、製造コストの低減を図ることができる。
次に、前述した温度定点セルを備えた温度定点装置を図４を参照して説明する。
温度定点装置は、横型可変電気炉３１を有する。この可変電気炉３１は、横置きされた円筒状の断熱材３２と、この断熱材３２の両端にそれぞれ着脱可能に配置され、中央に窓穴３３ａ，３３ｂが開口された円板状封止板３４ａ，３４ｂと、これら封止板３４ａ，３４ｂの外面に、その窓穴３３ａ，３３ｂを覆うように取り付けられた例えば石英ガラスからなる透明な円形窓３５ａ，３５ｂと、この断熱材３２および封止板３４ａ，３４ｂで囲まれた空間３６の内部に配置された黒鉛からなる円筒状のヒータエレメント３７とを備えている。このヒータエレメント３７は、図示しない制御器を有するヒータ電源に接続されている。アルゴンのような希ガスを導入するためのガス導入管３８は、左端側の封止板３４ａに連結されている。排気管３９は、一端が右端側の封止板３４ｂに連結され、他端が図示しない真空ポンプのような排気部材に連結されている。
前述した図３に示す温度定点セル１は、例えば黒鉛フェルトからなる円筒状断熱部材４０にそのセル１の空洞４がその断熱部材４０の右端側に位置するように挿入されている。例えば黒鉛フェルトからなる円板状断熱部材４１は、前記円筒状断熱部材４０の左端側に配置されている。温度定点セル１の空洞４と合致する穴が中央に開口された例えば黒鉛フェルトからなる円板状断熱部材４２は、前記円筒状断熱部材４０の右端側に配置されている。このような断熱部材４０〜４２で囲まれた温度定点セル１は、前記円筒状のヒータエレメント３７内にその空洞４と合致する穴が開口された円板状断熱部材４２が例えば右端側の封止板３４ｂに向くように装填されている。
In such melting and solidification of the eutectic of metal (or metal carbide) / carbon existing in the porous body 6 which is the fixed point material of the temperature fixed point cell 1, the protective tube 26 is inserted into the cavity 4 of the temperature fixed point cell 1. Then, the temperature of the temperature fixed point cell 1 is measured by the thermocouple 30 to be calibrated inserted into the protective tube 26. Calibration is performed by making the output of the calibration thermocouple 30 correspond to the eutectic melting point of the temperature fixed point cell 1.
Therefore, in the fixed point calibration of thermocouples, the metal (or metal carbide) / carbon eutectic present in the porous body has a higher melting point than copper, so the fixed point calibration is realized in the temperature range from 1100 ° C to over 3000 ° C. it can.
Further, in the temperature fixed point cell 1, since the porous body 6 is enclosed with a desired gap with respect to the inner surface of the graphite crucible 2 as shown in FIG. 1, the crucible 2 and the fixed point in the cooling process after fixed point calibration are fixed. The occurrence of stress on the crucible 2 due to the difference in thermal expansion with the substance 6 can also be avoided. Therefore, it is possible to prevent the crucible 2 from cracking and achieve a long life.
In the first embodiment, a thermocouple is used as the thermometer to be calibrated, but a high-temperature contact thermometer such as a resistance thermometer or a fiber thermometer can also be used.
(Second Embodiment)
FIG. 3 is a cross-sectional view showing a temperature fixed point cell according to the second embodiment. In FIG. 3, the same members as those in FIG.
In the temperature fixed point cell 1, for example, a cylindrical graphite support member 8 in which a plurality of graphite papers are laminated in the gap between the inner surface of the cylindrical crucible main body 3 constituting the crucible 2 and the porous body 6 is inserted into the crucible 2. For example, a disk-shaped support body 9 in which a plurality of graphite papers are stacked is inserted in the gap between the disk-shaped lid body 5 made of graphite and the porous body 6.
As the metal and metal carbide constituting the fixed point material, the same materials as described in the first embodiment are used.
The support may be formed from a single graphite body in addition to a laminate of graphite paper.
The above-mentioned temperature fixed point cell is manufactured by the following method, for example.
First, high-purity metal (or metal carbide) powder and high-purity graphite powder are mixed so that the graphite powder is larger than the eutectic composition of metal (or metal carbide) / carbon, and this mixed powder is a black body. The graphite crucible body having a cavity is filled. Subsequently, the main body was opened in a vertical electric furnace with the opening opened, and the inside of the furnace was replaced with argon to create an argon atmosphere, or the furnace was evacuated to a high vacuum state. Thereafter, the metal is sintered by heating to a temperature lower than the melting point of the eutectic and maintaining the temperature for a desired time. At this time, the graphite powder mixture containing the sintered metal is formed in the crucible body with a desired gap between the inner surface and the inner surface. After turning off the power to the heater of the electric furnace and cooling to room temperature, for example, a cylindrical graphite support member in which a plurality of graphite papers are stacked is interposed in the gap between the crucible body and the mixture, and a plurality of sheets are provided at the upper end of the mixture. A disk-shaped graphite support member laminated with graphite paper is stacked, and a graphite lid is fixed to the opening end of the main body. Again, the heater of the electric furnace is energized and heated to a temperature higher than the melting point of the eutectic so that the metal of the mixture melts and is covered with coexisting planar graphite powder, and the metal is separated in an island state. Is done. Subsequently, eutectic of the metal and carbon is produced in the state where the carbon powder coexists in the process of solidifying the metal by turning off the power to the heater of the electric furnace and cooling to room temperature. For this reason, a porous body having a cylindrical outer shape, which is a fixed-point substance having a composition containing carbon powder, in which a eutectic of metal (or metal carbide) and carbon exists, is formed inside the graphite support member, A temperature fixed point cell is manufactured.
In the manufacture of such a temperature fixed point cell, it becomes possible to obtain a porous body as a fixed point substance by one filling (casting) and heating of the mixed powder as a raw material, and the manufacturing cost can be reduced.
Next, a temperature fixed point device including the above-described temperature fixed point cell will be described with reference to FIG.
The temperature fixed point device has a horizontal variable electric furnace 31. The variable electric furnace 31 includes a horizontally installed cylindrical heat insulating material 32 and a disc-shaped sealing plate that is detachably disposed at both ends of the heat insulating material 32 and has window holes 33a and 33b opened in the center. 34a, 34b, transparent circular windows 35a, 35b made of, for example, quartz glass, which are attached to the outer surfaces of the sealing plates 34a, 34b so as to cover the window holes 33a, 33b, the heat insulating material 32 and the sealing And a cylindrical heater element 37 made of graphite disposed in a space 36 surrounded by the plates 34a and 34b. The heater element 37 is connected to a heater power source having a controller (not shown). A gas introduction pipe 38 for introducing a rare gas such as argon is connected to the sealing plate 34a on the left end side. One end of the exhaust pipe 39 is connected to the sealing plate 34b on the right end side, and the other end is connected to an exhaust member such as a vacuum pump (not shown).
The temperature fixed point cell 1 shown in FIG. 3 described above is inserted into a cylindrical heat insulating member 40 made of, for example, graphite felt so that the cavity 4 of the cell 1 is positioned on the right end side of the heat insulating member 40. For example, the disc-shaped heat insulating member 41 made of graphite felt is disposed on the left end side of the cylindrical heat insulating member 40. A disk-like heat insulating member 42 made of, for example, graphite felt, having a hole that matches the cavity 4 of the temperature fixed point cell 1 in the center, is disposed on the right end side of the cylindrical heat insulating member 40. In the temperature fixed point cell 1 surrounded by the heat insulating members 40 to 42, the disk-shaped heat insulating member 42 in which a hole matching the cavity 4 is opened in the cylindrical heater element 37 is, for example, a seal on the right end side. It is loaded so as to face the stop plate 34b.
モニタ用放射温度計４３は、前記可変電気炉３１の外部に左端側の封止板３４ａの窓３５ａに対向するように配置されている。このモニタ用放射温度計４３は、前記ヒータ電源の制御器に接続され、温度測定結果が前記制御器に入力される。温度測定結果が制御器に入力されると、その制御器から前記ヒータ電源に制御信号が出力されて、前記ヒータエレメント３７の発熱温度を制御する。
このような図４に示す構成の温度定点装置による定点校正方法を説明する。
まず、横型可変電気炉３１の外部に被校正放射温度計４４を温度定点セル１の黒体空洞４が向いた右端側の封止板３４ｂの窓３５ｂに対向するように配置する。図示しない真空ポンプを作動して断熱材３２および封止板３４ａ、３４ｂで囲まれた空間３６内の空気を排気管３９を通して排気すると共に、例えばアルゴンガスをガス導入管３８を通して前記空間内３６に導入してアルゴン雰囲気にする。このように断熱材３２および封止板３４ａ、３４ｂで囲まれた空間３６内をアルゴン雰囲気にすることにより、その空間３６内の装填された温度定点セル１の黒鉛るつぼの酸化焼失を防ぐと共に、同セル１に封入された定点物質の酸化を防止する。
前記空間３６内がアルゴンで十分に置換された後、図示しないヒータ電源から円筒状ヒータエレメント３７に通電して発熱させてそのヒータエレメント３７内の温度を所望の速度で昇温させる。このようなヒータエレメント３７の昇温により装填された図３に示す温度定点セル１の定点物質である多孔質体６に存在する金属（または金属炭化物）／炭素の共晶の融点近傍に達すると、その融点近傍で温度を上下動させる。このとき、温度定点セル１は断熱部材４０〜４２で囲まれているために温度分布を均一化することが可能になる。前記金属（または金属炭化物）／炭素の共晶が融点を超えると、多孔質体６を構成する炭素（黒鉛）が僅かに溶出するが、再度温度を下げると余分な黒鉛は多孔質体６の面状黒鉛粉末に析出するため、凝固点に至るときには共晶の組成比に戻る。そのため、再現性の良い溶解・凝固プラトーが観測される。共晶は、多孔質体６の一方の成分およびるつぼ材料と同じ黒鉛と純金属とからなる組成を有するため、本質的に前記黒鉛が不純物となり得ず、凝固点降下は生じない。
The monitoring radiation thermometer 43 is arranged outside the variable electric furnace 31 so as to face the window 35a of the sealing plate 34a on the left end side. The monitoring radiation thermometer 43 is connected to the controller of the heater power supply, and the temperature measurement result is input to the controller. When the temperature measurement result is input to the controller, a control signal is output from the controller to the heater power supply to control the heat generation temperature of the heater element 37.
A fixed point calibration method using the temperature fixed point apparatus having the configuration shown in FIG. 4 will be described.
First, the calibrated radiation thermometer 44 is disposed outside the horizontal variable electric furnace 31 so as to face the window 35b of the sealing plate 34b on the right end side where the blackbody cavity 4 of the temperature fixed point cell 1 faces. A vacuum pump (not shown) is operated to exhaust the air in the space 36 surrounded by the heat insulating material 32 and the sealing plates 34a and 34b through the exhaust pipe 39, and for example, argon gas is introduced into the space 36 through the gas introduction pipe 38. Introduced to an argon atmosphere. In this way, by making the inside of the space 36 surrounded by the heat insulating material 32 and the sealing plates 34a and 34b an argon atmosphere, oxidation burning of the graphite crucible of the temperature fixed point cell 1 loaded in the space 36 is prevented, The oxidation of the fixed point substance enclosed in the cell 1 is prevented.
After the space 36 is sufficiently replaced with argon, a cylindrical heater element 37 is energized from a heater power source (not shown) to generate heat, and the temperature in the heater element 37 is increased at a desired rate. When reaching the melting point of the eutectic of metal (or metal carbide) / carbon existing in the porous body 6 which is the fixed point material of the temperature fixed point cell 1 shown in FIG. The temperature is moved up and down in the vicinity of the melting point. At this time, since the temperature fixed point cell 1 is surrounded by the heat insulating members 40 to 42, the temperature distribution can be made uniform. When the metal (or metal carbide) / carbon eutectic exceeds the melting point, the carbon (graphite) constituting the porous body 6 is slightly eluted, but when the temperature is lowered again, the excess graphite is removed from the porous body 6. Since it precipitates in the planar graphite powder, it returns to the eutectic composition ratio when it reaches the freezing point. Therefore, a reproducible dissolution / coagulation plateau is observed. Since the eutectic has the same composition of graphite and pure metal as one of the components of the porous body 6 and the crucible material, the graphite cannot essentially be an impurity, and freezing point depression does not occur.
このような温度定点セル１の定点物質である多孔質体６に存在する金属（または金属炭化物）／炭素の共晶の溶融・凝固において、横型可変電気炉３１の外部に配置した被校正放射温度計４４により石英ガラス製窓３５ｂを通して温度定点セル１の空洞（黒体空洞）４の放射光を捉え、温度定点セル１の温度を測定する。この被校正放射温度計４４の出力と温度定点セル１の共晶の融点を対応させることにより校正を行う。
したがって、前記放射温度計の定点校正において、前記多孔質体に存在する金属（または金属炭化物）／炭素の共晶は融点が銅より高いために１１００℃から３０００℃を超える温度域で定点の校正を実現できる。
また、前記温度定点セル１において多孔体６は図３に示すように黒鉛るつぼ２の内面に例えば複数枚の黒鉛ペーパを積層した黒鉛支持部材８、９を介して封入されているため、定点校正後の冷却過程でのるつぼ２と定点物質６との間の熱膨張差に起因するるつぼ２へのストレス発生を前記黒鉛支持部材８、９で吸収できる。特に、複数枚の黒鉛ペーパを積層した黒鉛支持部材８、９を用いることによって、熱膨張差に起因するるつぼ２へのストレス発生をより効果的に吸収することが可能になる。したがって、るつぼ２の亀裂発生を防止して長寿命化を達成できる。
なお、第２実施形態において温度定点セルが組込まれる温度定点装置は、前述した図４に示す構造に限らず、前述した図２に示す縦型可変電気炉を有する構造でもよい。
（第３実施形態）
図５は、この第３実施形態に係る温度定点セルを示す断面図である。なお、図５において図１と同様な部材は同符号を付して説明を省略する。
この温度定点セル１は、るつぼ２を構成する円筒状のるつぼ本体３内に定点物質である（ａ）金属または金属炭化物と炭素との共晶と（ｂ）炭素粉末とからなる顆粒１０を封入した構造を有する。
前記定点物質を構成する金属、金属炭化物は、第１実施形態で説明したものと同様なものが用いられる。
前述した温度定点セルは、例えば次のような方法により製造される。
まず、高純度の金属（または金属炭化物）の粉末と高純度の黒鉛粉末とを金属（または金属炭化物）／炭素の共晶組成より黒鉛粉末が多くなるように混合し、この混合粉末を黒体空洞を有する黒鉛製のるつぼ本体内に充填する。なお、この混合粉末は、前述した第１、第２の実施形態に比べてより多い量の黒鉛粉末を含有させる。つづいて、この本体の開口部を開放した状態で縦型電気炉内に設置し、前記炉内をアルゴンで置換してアルゴン雰囲気にするか、または炉内を真空引きして高真空状態にした後、前記共晶の融点より高い温度まで加熱することにより、金属が溶融し、共存する個々の黒鉛粒子に付着する。ひきつづき、電気炉のヒータへの通電を切り、室温まで冷却することにより、金属が凝固する過程で黒鉛粉末を取り囲むように金属と黒鉛との共晶が生成される。このため、（ａ）金属または金属炭化物と炭素との共晶と（ｂ）炭素粉末とからなる顆粒が作られる。その後、るつぼ本体の開口端に黒鉛製の蓋体を固定して定点物質である前記顆粒を気密に封止することにより温度定点セルが製造される。
このような温度定点セルの製造において、原料である混合粉末の一回の充填（鋳込み）、加熱によって定点物質である顆粒を得ること可能になり、製造コストの低減を図ることができる。
前述した温度定点セルを備えた温度定点装置は、前述した図２に示す縦型可変電気炉を有する構造、図４に示す横型可変電気炉を有する構造、のものが挙げられる。このような構成の温度定点装置（例えば図４に示す横型可変電気炉を有する構造）による定点校正方法を以下に説明する。
まず、横型可変電気炉３１の外部に被校正放射温度計４４を温度定点セル１の黒体空洞４が向いた右端側の封止板３４ｂの窓３５ｂに対向するように配置する。図示しない真空ポンプを作動して断熱材３２および封止板３４ａ、３４ｂで囲まれた空間３６内の空気を排気管３９を通して排気すると共に、例えばアルゴンガスをガス導入管３８を通して前記空間内３６に導入してアルゴン雰囲気にする。このように断熱材３２および封止板３４ａ、３４ｂで囲まれた空間３６内をアルゴン雰囲気にすることにより、その空間３６内の装填された温度定点セル１の黒鉛るつぼの酸化焼失を防ぐと共に、同セル１に封入された定点物質の酸化を防止する。
前記空間３６内がアルゴンで十分に置換された後、図示しないヒータ電源から円筒状ヒータエレメント３７に通電して発熱させてそのヒータエレメント３７内の温度を所望の速度で昇温させる。このようなヒータエレメント３７の昇温により装填された図５に示す温度定点セル１の定点物質である顆粒１０に存在する金属（または金属炭化物）／炭素の共晶の融点近傍に達すると、その融点近傍で温度を上下動させる。このとき、温度定点セル１は断熱部材４０〜４２で囲まれているために温度分布を均一化することが可能になる。前記金属（または金属炭化物）／炭素の共晶が融点を超えると、顆粒１０を構成する炭素（黒鉛）が僅かに溶出するが、再度温度を下げると余分な黒鉛は顆粒１０の黒鉛粉末に析出するため、凝固点に至るときには共晶の組成比に戻る。そのため、再現性の良い溶解・凝固プラトーが観測される。共晶は、顆粒１０の一方の成分およびるつぼ材料と同じ黒鉛と純金属とかなる組成を有するため、本質的に前記黒鉛が不純物となり得ず、凝固点降下は生じない。
In the melting and solidification of the metal (or metal carbide) / carbon eutectic present in the porous body 6 which is the fixed point material of the temperature fixed point cell 1, the radiation temperature to be calibrated arranged outside the horizontal variable electric furnace 31 A total 44 captures the emitted light from the cavity (black body cavity) 4 of the temperature fixed point cell 1 through the quartz glass window 35b, and measures the temperature of the temperature fixed point cell 1. Calibration is performed by making the output of the calibration thermometer 44 correspond to the eutectic melting point of the temperature fixed cell 1.
Therefore, in the fixed point calibration of the radiation thermometer, the metal (or metal carbide) / carbon eutectic present in the porous body has a melting point higher than that of copper, so the fixed point is calibrated in the temperature range exceeding 1100 ° C. to 3000 ° C. Can be realized.
Further, in the temperature fixed point cell 1, the porous body 6 is sealed on the inner surface of the graphite crucible 2 via, for example, graphite support members 8 and 9 in which a plurality of graphite papers are laminated as shown in FIG. The graphite support members 8 and 9 can absorb the stress generated in the crucible 2 due to the difference in thermal expansion between the crucible 2 and the fixed point material 6 in the subsequent cooling process. In particular, by using the graphite support members 8 and 9 in which a plurality of graphite papers are laminated, it is possible to more effectively absorb the stress generated in the crucible 2 due to the difference in thermal expansion. Therefore, it is possible to prevent the crucible 2 from cracking and achieve a long life.
In addition, the temperature fixed point device in which the temperature fixed point cell is incorporated in the second embodiment is not limited to the structure shown in FIG. 4 described above, but may be a structure having the vertical variable electric furnace shown in FIG.
(Third embodiment)
FIG. 5 is a sectional view showing a temperature fixed point cell according to the third embodiment. In FIG. 5, the same members as those in FIG.
This temperature fixed point cell 1 encloses a granule 10 made of a fixed point substance (a) eutectic of metal or metal carbide and carbon and (b) carbon powder in a cylindrical crucible body 3 constituting a crucible 2. Has the structure.
As the metal and metal carbide constituting the fixed point material, the same materials as described in the first embodiment are used.
The above-mentioned temperature fixed point cell is manufactured by the following method, for example.
First, high-purity metal (or metal carbide) powder and high-purity graphite powder are mixed so that the graphite powder is larger than the eutectic composition of metal (or metal carbide) / carbon, and this mixed powder is a black body. The graphite crucible body having a cavity is filled. In addition, this mixed powder contains a larger amount of graphite powder than the first and second embodiments described above. Subsequently, the main body was opened in a vertical electric furnace with the opening opened, and the inside of the furnace was replaced with argon to create an argon atmosphere, or the furnace was evacuated to a high vacuum state. Thereafter, by heating to a temperature higher than the melting point of the eutectic, the metal melts and adheres to the coexisting individual graphite particles. Subsequently, by turning off the power to the heater of the electric furnace and cooling to room temperature, a eutectic of metal and graphite is generated so as to surround the graphite powder in the process of solidifying the metal. For this reason, granules comprising (a) a eutectic of metal or metal carbide and carbon and (b) carbon powder are produced. Thereafter, a temperature-fixed cell is manufactured by fixing a graphite lid to the open end of the crucible body and hermetically sealing the granules as a fixed-point substance.
In the manufacture of such a temperature fixed point cell, it becomes possible to obtain granules as a fixed point substance by one filling (casting) and heating of the mixed powder as a raw material, and the manufacturing cost can be reduced.
Examples of the temperature fixed point device provided with the temperature fixed point cell described above include the structure having the vertical variable electric furnace shown in FIG. 2 and the structure having the horizontal variable electric furnace shown in FIG. A fixed point calibration method using a temperature fixed point apparatus having such a configuration (for example, a structure having a horizontal variable electric furnace shown in FIG. 4) will be described below.
First, the calibrated radiation thermometer 44 is disposed outside the horizontal variable electric furnace 31 so as to face the window 35b of the sealing plate 34b on the right end side where the blackbody cavity 4 of the temperature fixed point cell 1 faces. A vacuum pump (not shown) is operated to exhaust the air in the space 36 surrounded by the heat insulating material 32 and the sealing plates 34a and 34b through the exhaust pipe 39, and for example, argon gas is introduced into the space 36 through the gas introduction pipe 38. Introduced to an argon atmosphere. In this way, by making the inside of the space 36 surrounded by the heat insulating material 32 and the sealing plates 34a and 34b an argon atmosphere, oxidation burning of the graphite crucible of the temperature fixed point cell 1 loaded in the space 36 is prevented, The oxidation of the fixed point substance enclosed in the cell 1 is prevented.
After the space 36 is sufficiently replaced with argon, a cylindrical heater element 37 is energized from a heater power source (not shown) to generate heat, and the temperature in the heater element 37 is increased at a desired rate. When reaching the melting point of the metal (or metal carbide) / carbon eutectic present in the granule 10 which is the fixed point material of the temperature fixed point cell 1 shown in FIG. Move the temperature up and down near the melting point. At this time, since the temperature fixed point cell 1 is surrounded by the heat insulating members 40 to 42, the temperature distribution can be made uniform. When the metal (or metal carbide) / carbon eutectic exceeds the melting point, the carbon (graphite) constituting the granules 10 is slightly eluted, but when the temperature is lowered again, excess graphite precipitates in the graphite powder of the granules 10 Therefore, when reaching the freezing point, the composition ratio of the eutectic is restored. Therefore, a reproducible dissolution / coagulation plateau is observed. Since the eutectic has the same composition of graphite and pure metal as one component of the granule 10 and the crucible material, the graphite cannot essentially be an impurity and freezing point depression does not occur.
このような温度定点セル１の定点物質である顆粒１０に存在する金属（または金属炭化物）／炭素の共晶の溶融・凝固において、横型可変電気炉３１の外部に配置した被校正放射温度計４４により石英ガラス製の窓３５ｂを通して温度定点セル１の空洞（黒体空洞）４の放射光を捉え、温度定点セル１の温度を測定する。この被校正放射温度計４４の出力と温度定点セル１の共晶の融点を対応させることにより校正を行う。
したがって、前記放射温度計の定点校正において、前記多孔質体に存在する金属（または金属炭化物）／炭素の共晶は融点が銅より高いために１１００℃から３０００℃を超える温度域で定点の校正を実現できる。
また、前記温度定点セル１において定点物質が顆粒の形態を有するため、定点校正後の冷却過程でのるつぼ２と定点物質（顆粒）１０との間の熱膨張差に起因するるつぼ２へのストレス発生も回避できる。したがって、るつぼ２の亀裂発生を防止して長寿命化を達成できる。
以下、本発明の実施例を前述した図面を参照して説明する。
（実施例１）
まず、図１に示す純化した黒鉛製のるつぼ本体２を用意する。この本体２は、外形２４ｍｍ、長さ４５ｍｍの片封じ円筒状をなし、その片封じ部に直径３ｍｍ、深さ３４ｍｍの円筒状の空洞４を形成した形状を有する。
次いで、平均粒径２０μｍ、純度９９．９９９％の白金粉末３０ｇと平均粒径７７μｍ、純度９９．９９９９％の黒鉛粉末０．４ｇとを白金／炭素の共晶組成より黒鉛粉末が多くなるように混合し、この混合粉末を前記るつぼ本体内に充填した。つづいて、このるつぼ本体の開口部を開放した状態で縦型電気炉内に設置し、前記炉内をアルゴンで置換してアルゴン雰囲気にした後、白金／炭素共晶の融点（１７３８℃）より約５０℃低い温度まで加熱して、その温度を約３０分間維持ことにより白金が焼結された。このとき、白金焼結物を含む黒鉛粉末の混合体はるつぼ本体内にその内面との間に所望の隙間をあけて生成された。電気炉のヒータへの通電を切り、室温まで冷却した後、るつぼ本体と混合体の隙間（約１ｍｍ）に複数枚の黒鉛ペーパを積層した円筒状の黒鉛支持部材を介在し、混合体の上端に複数枚の黒鉛ペーパを積層した円板状の黒鉛支持部材を重ね、黒鉛製の蓋体を本体の開口端に固定した。再度、電気炉のヒータへの通電を行って前記共晶の融点より高い温度に加熱することにより前記混合体の白金が溶融し、共存する面状黒鉛粉末で覆われて白金が島状態で分離された。ひきつづき、電気炉のヒータへの通電を切り、室温まで冷却するにより前記白金が凝固する過程で炭素粉末が共存された状態で白金と炭素との共晶が生成された。このため、白金／炭素共晶が存在された、黒鉛粉末を含む組成を有する定点物質である外形が円柱状の多孔質体が前記黒鉛支持部材の内部に作られ、前述した図３に示す構造の温度定点セルが製造された。
In the melting and solidification of the eutectic of metal (or metal carbide) / carbon present in the granule 10 as the fixed point material of the temperature fixed point cell 1, a calibrated radiation thermometer 44 disposed outside the horizontal variable electric furnace 31. Thus, the radiation of the cavity (black body cavity) 4 of the temperature fixed point cell 1 is captured through the quartz glass window 35b, and the temperature of the temperature fixed point cell 1 is measured. Calibration is performed by making the output of the calibration thermometer 44 correspond to the eutectic melting point of the temperature fixed cell 1.
Therefore, in the fixed point calibration of the radiation thermometer, the metal (or metal carbide) / carbon eutectic present in the porous body has a melting point higher than that of copper, so the fixed point is calibrated in the temperature range exceeding 1100 ° C. to 3000 ° C. Can be realized.
In addition, since the fixed point substance has a granular form in the temperature fixed point cell 1, the stress on the crucible 2 due to the difference in thermal expansion between the crucible 2 and the fixed point substance (granule) 10 in the cooling process after the fixed point calibration. Occurrence can also be avoided. Therefore, it is possible to prevent the crucible 2 from cracking and achieve a long life.
Embodiments of the present invention will be described below with reference to the drawings described above.
Example 1
First, a purified graphite crucible body 2 shown in FIG. 1 is prepared. The main body 2 has a single-sealed cylindrical shape having an outer shape of 24 mm and a length of 45 mm, and has a shape in which a cylindrical cavity 4 having a diameter of 3 mm and a depth of 34 mm is formed in the single-sealed portion.
Next, 30 g of platinum powder having an average particle size of 20 μm and a purity of 99.999% and 0.4 g of graphite powder having an average particle size of 77 μm and a purity of 99.9999% are added so that the graphite powder is larger than the eutectic composition of platinum / carbon. The mixed powder was filled into the crucible body. Subsequently, the crucible body was opened in a vertical electric furnace with the opening of the crucible body opened, and the inside of the furnace was replaced with argon to form an argon atmosphere. Then, from the melting point of platinum / carbon eutectic (1738 ° C.) Platinum was sintered by heating to about 50 ° C. and maintaining that temperature for about 30 minutes. At this time, the graphite powder mixture containing the platinum sintered product was formed in the crucible body with a desired gap between the inner surface and the inner surface. After turning off the electric power to the heater of the electric furnace and cooling to room temperature, a cylindrical graphite support member in which a plurality of graphite papers are stacked in the gap (about 1 mm) between the crucible body and the mixture is interposed, and the upper end of the mixture A disk-shaped graphite support member in which a plurality of sheets of graphite paper are laminated is stacked on top of each other, and a graphite lid is fixed to the open end of the main body. Once again, the heater of the electric furnace is energized and heated to a temperature higher than the melting point of the eutectic so that the platinum in the mixture melts and is covered with the coexisting planar graphite powder and is separated in an island state. It was done. Subsequently, by turning off the electric power to the heater of the electric furnace and cooling to room temperature, a platinum and carbon eutectic was produced in the state where the carbon powder coexisted in the process of solidifying the platinum. Therefore, a porous body having a cylindrical outer shape, which is a fixed-point substance having a composition containing graphite powder, in which platinum / carbon eutectic is present, is formed inside the graphite support member, and has the structure shown in FIG. Temperature fixed point cells were manufactured.
得られた温度定点セルを前述した図４に示す横型可変電気炉を有する温度定点装置に組込み、第２実施形態で説明したの同様な放射温度計の定点校正を行った。すなわち、横型可変電気炉３１の断熱材３２および封止板３４ａ、３４ｂで囲まれた空間３６内をアルゴン雰囲気に置換した後、ヒータエレメント３７により約３０分間で温度定点セル１の多孔質体に存在する白金／炭素共晶をその融点まで約６０℃／分間で昇温し、融点近傍で炉内温度を上下させた。このとき、図６のＡに示す融解・凝固のプラトーを実現できた。プラトーでの放射温度計の出力と白金／炭素共晶の融点（１７３８℃）とを対応させて定点校正を行った。
黒鉛るつぼに白金／炭素の共晶組織を有する定点物質を封入した特許文献１（特許第２９８７４５９号）の温度定点セルは、４０ｍＫの融解プラトーの再現性（標準偏差）が得られるのに対し、本実施例１の温度定点セルの同再現性が７０ｍＫとやや劣るものの、実用上十分な性能である。また、プラトーの温度値は前記再現性の範囲では差が見られなかった。
前記校正作業の終了後、横型可変電気炉のヒータエレメントの電源を切り、約１００℃／分間の降温速度で約１時間後に室温に戻して温度定点セルを炉から取り出した。このような急激な昇温・降温の温度変化にも本実施例１の温度定点セルのるつぼに亀裂が見られず、十分な耐熱衝撃瀬を有することが確認された。これに対し、黒鉛るつぼに白金／炭素の共晶組織を有する定点物質を封入した特許文献１（特許第２９８７４５９号）の温度定点セルは、るつぼへの亀裂発生を防ぐために昇温・降温を約１０〜１５℃／分間と比較的な緩慢な速度で行う必要があった。ただし、このような昇温・降温の条件でもるつぼの亀裂発生がしばしば起こった。このようなことから、本実施例１の温度定点セルは亀裂、破損が生じず、半永久的に繰り返し使用が可能である上、校正作業の効率化を図ることが可能になる。
さらに、実施例１と同サイズの黒鉛るつぼを用い、このるつぼに白金／炭素の共晶組織を有する定点物質を封入した特許文献１（特許第２９８７４５９号）の温度定点セルに製造においては８０ｇの白金を必要とし、かつ鋳込み作業は各原料粉末が融解した時に充電率が著しく減少することから、るつぼ内に白金／炭素の共晶組織を有する定点物質を完全に充填するには１０回程度の鋳込み作業を繰り返す必要があった。これに対し、本実施例１の温度定点セルの製造では鋳込み作業が１回で済み、かつ白金の使用量も半減できる。したがって、作業の簡略化と原料コストの低減化を達成できた。
（実施例２）
平均粒径２０μｍ、純度９９．９９９％の白金粉末３０ｇと平均粒径７７μｍ、純度９９．９９９９％の黒鉛粉末１．６ｇとを白金／炭素の共晶組成より黒鉛粉末が実施例１よりさらに多くなるように混合し、この混合粉末を実施例１と同様な形状、寸法の黒鉛製るつぼ本体内に充填した。つづいて、このるつぼ本体の開口部を開放した状態で縦型電気炉内に設置し、前記炉内をアルゴンで置換してアルゴン雰囲気にした後、白金／炭素共晶の融点（１７３８℃）より高い温度まで加熱することにより、白金が溶融し、共存する個々の黒鉛粒子に付着した。ひきつづき、電気炉のヒータへの通電を切り、室温まで冷却することにより、白金が凝固する過程で黒鉛粉末を取り囲むように白金と炭素との共晶が生成された。このため、るつぼ本体内に十分な量で充填された白金／炭素共晶と黒鉛粉末とからなる顆粒が作られた。その後、黒鉛製の蓋体をるつぼ本体の開口端に固定して定点物質である前記顆粒を気密に封止することにより前述した図５に示す構造の温度定点セルが製造された。
The obtained temperature fixed point cell was incorporated in the temperature fixed point apparatus having the horizontal variable electric furnace shown in FIG. 4 described above, and fixed point calibration of the same radiation thermometer described in the second embodiment was performed. That is, after replacing the space 36 surrounded by the heat insulating material 32 and the sealing plates 34a and 34b of the horizontal variable electric furnace 31 with an argon atmosphere, the heater element 37 makes the porous body of the temperature fixed point cell 1 in about 30 minutes. The existing platinum / carbon eutectic was heated up to its melting point at about 60 ° C./min, and the furnace temperature was raised and lowered near the melting point. At this time, the melting / solidification plateau shown in FIG. Fixed point calibration was performed by matching the output of the radiation thermometer at the plateau with the melting point of platinum / carbon eutectic (1738 ° C.).
In the temperature fixed point cell of Patent Document 1 (Patent No. 2998759) in which a fixed point substance having a platinum / carbon eutectic structure is enclosed in a graphite crucible, a reproducibility (standard deviation) of a melting plateau of 40 mK is obtained. Although the reproducibility of the temperature fixed point cell of Example 1 is slightly inferior to 70 mK, it is a practically sufficient performance. Further, no difference was observed in the temperature value of the plateau within the reproducibility range.
After completion of the calibration work, the heater element of the horizontal variable electric furnace was turned off, returned to room temperature after about 1 hour at a temperature lowering rate of about 100 ° C./min, and the temperature fixed point cell was taken out of the furnace. It was confirmed that there was no crack in the crucible of the temperature fixed point cell of Example 1 and that the thermal shock was sufficient even in such a sudden temperature rise / fall temperature change. On the other hand, in the temperature fixed point cell of Patent Document 1 (Patent No. 2998759) in which a fixed point material having a platinum / carbon eutectic structure is enclosed in a graphite crucible, the temperature rise / fall is reduced to prevent cracking in the crucible. It had to be performed at a slower rate compared to 10-15 ° C / min. However, crucible cracks often occurred even under such temperature rising / falling conditions. For this reason, the temperature fixed point cell of the first embodiment is not cracked or damaged, and can be used repeatedly semipermanently, and the efficiency of the calibration work can be improved.
Further, a graphite crucible having the same size as that of Example 1 was used, and the fixed-point substance having a platinum / carbon eutectic structure was enclosed in the crucible. In the production of the temperature fixed point cell of Patent Document 1 (Patent No. 2998759), 80 g Since platinum is required and the charging rate is remarkably reduced when each raw material powder is melted, casting is performed about 10 times to completely fill the crucible with a fixed point material having a platinum / carbon eutectic structure. It was necessary to repeat the casting operation. On the other hand, in the production of the temperature fixed point cell according to the first embodiment, only one casting operation is required, and the amount of platinum used can be halved. Therefore, simplification of operations and reduction of raw material costs were achieved.
(Example 2)
30 g of platinum powder having an average particle size of 20 μm and a purity of 99.999% and 1.6 g of graphite powder having an average particle size of 77 μm and a purity of 99.9999% are more graphite powder than Example 1 than the eutectic composition of platinum / carbon. The mixed powder was filled into a graphite crucible body having the same shape and dimensions as in Example 1. Subsequently, the crucible body was opened in a vertical electric furnace with the opening of the crucible body opened, and the inside of the furnace was replaced with argon to form an argon atmosphere. Then, from the melting point of platinum / carbon eutectic (1738 ° C.) By heating to a high temperature, the platinum melted and adhered to the coexisting individual graphite particles. Subsequently, when the heater of the electric furnace was turned off and cooled to room temperature, a eutectic of platinum and carbon was formed so as to surround the graphite powder in the process of solidifying platinum. For this reason, granules composed of platinum / carbon eutectic and graphite powder filled in a sufficient amount in the crucible body were produced. Thereafter, the temperature-fixed cell having the structure shown in FIG. 5 was manufactured by fixing the graphite lid to the open end of the crucible body and hermetically sealing the granule as the fixed-point material.
得られた温度定点セルを前述した図４に示す横型可変電気炉を有する温度定点装置に組込み、実施例１と同様に放射温度計の定点校正を行った。このとき、図６のＢに示す融解・凝固のプラトーを実現できた。プラトーでの放射温度計の出力と白金／炭素共晶の融点（１７３８℃）とを対応させて定点校正を行った。
本実施例２の温度定点セルの融解プラトーの再現性（標準偏差）は１００ｍＫと黒鉛るつぼに白金／炭素の共晶組織を有する定点物質を封入した特許第２９８７４５９号の温度定点セルに比べて劣るものの、２次標準、移送標準として実用上十分な性能である。また、プラトーの温度値は前記再現性の範囲では差が見られなかった。
前記校正作業の終了後、横型可変電気炉のヒータエレメントの電源を切り、約１００℃／分間の降温速度で約１時間後に室温に戻して温度定点セルを炉から取り出した。このような急激な昇温・降温の温度変化にも本実施例１の温度定点セルのるつぼに亀裂が見られず、十分な耐熱衝撃瀬を有することが確認された。さらに、本実施例２の温度定点セルの製造では鋳込み作業が１回で済み、かつ白金の使用量も半減でき、作業の簡略化と原料コストの低減化を達成できた。
The obtained temperature fixed point cell was incorporated into the temperature fixed point apparatus having the horizontal variable electric furnace shown in FIG. 4 described above, and fixed point calibration of the radiation thermometer was performed in the same manner as in Example 1. At this time, the melting / solidification plateau shown in FIG. Fixed point calibration was performed by matching the output of the radiation thermometer at the plateau with the melting point of platinum / carbon eutectic (1738 ° C.).
The reproducibility (standard deviation) of the melting plateau of the temperature fixed point cell of Example 2 is inferior to the temperature fixed point cell of Japanese Patent No. 2998759 in which a fixed point substance having a platinum / carbon eutectic structure is enclosed in a graphite crucible of 100 mK. However, it is a practically sufficient performance as a secondary standard and transfer standard. Further, no difference was observed in the temperature value of the plateau within the reproducibility range.
After completion of the calibration work, the heater element of the horizontal variable electric furnace was turned off, returned to room temperature after about 1 hour at a temperature lowering rate of about 100 ° C./min, and the temperature fixed point cell was taken out of the furnace. It was confirmed that there was no crack in the crucible of the temperature fixed point cell of Example 1 and that the thermal shock was sufficient even in such a sudden temperature rise / fall temperature change. Furthermore, in the production of the temperature fixed point cell of Example 2, only one casting operation was required, and the amount of platinum used could be halved, thereby simplifying the operation and reducing the raw material cost.
１…温度定点セル、２…るつぼ、３…るつぼ本体、４…空洞、５…蓋体、６…定点物質（多孔質体）、８，９…支持体、１０…定点物質（顆粒）、２１…縦型可変電気炉、２３，３７…ヒータエレメント、２５…炉心管、２６…保護管、２９…モニタ用熱電対、３０…被校正熱電対、３１…横型可変電気炉、４３…モニタ用放射温度計、４４…被校正放射温度計。 DESCRIPTION OF SYMBOLS 1 ... Temperature fixed point cell, 2 ... Crucible, 3 ... Crucible body, 4 ... Cavity, 5 ... Cover body, 6 ... Fixed point substance (porous body), 8, 9 ... Support, 10 ... Fixed point substance (granule), 21 ... vertical variable electric furnace, 23, 37 ... heater element, 25 ... core tube, 26 ... protective tube, 29 ... monitoring thermocouple, 30 ... thermocouple to be calibrated, 31 ... horizontal variable electric furnace, 43 ... radiation for monitoring Thermometer 44 ... Radiated thermometer to be calibrated.
Claims (10)
前記定点物質は、金属または金属炭化物と炭素との共晶が存在された、炭素粉末を含む多孔質体からなることを特徴とする温度定点セル。 A temperature fixed point cell including a crucible containing carbon and a fixed point substance enclosed in the crucible;
The temperature fixed point cell, wherein the fixed point substance is a porous body containing carbon powder in which a eutectic of metal or metal carbide and carbon is present.
前記定点物質は、（ａ）金属または金属炭化物と炭素との共晶と（ｂ）炭素粉末とからなる顆粒であることを特徴とする温度定点セル。 A temperature fixed point cell including a crucible containing carbon and a fixed point substance enclosed in the crucible;
The temperature fixed point cell, wherein the fixed point substance is a granule composed of (a) a eutectic of metal or metal carbide and carbon and (b) carbon powder.
前記温度定点セルが内部に設置され、その温度定点セルの周囲温度を上昇または下降させる炉と
を具備することを特徴とする温度定点装置。 The temperature fixed point cell according to claim 1 or 5,
A temperature fixed point device comprising: a furnace in which the temperature fixed point cell is installed, and an ambient temperature of the temperature fixed point cell is increased or decreased.
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| KR100817437B1 (en) | 2006-07-13 | 2008-03-27 | 한국표준과학연구원 | The multi-fixed-point cells and temperature calibration system using it |
| JP5590454B2 (en) * | 2010-10-05 | 2014-09-17 | 株式会社リコー | Electrical element, integrated element and electronic circuit |
| CN104549594B (en) * | 2015-01-23 | 2016-04-13 | 中国航空工业集团公司北京长城计量测试技术研究所 | A kind of metal-carbon high temperature eutectic point reproduction crucible |
| CN110560191B (en) * | 2018-12-11 | 2021-08-31 | 中国航空工业集团公司北京长城计量测试技术研究所 | High-temperature eutectic point crucible with dynamically-variable volume |
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| JP3404531B2 (en) * | 2001-03-02 | 2003-05-12 | 独立行政法人産業技術総合研究所 | Temperature calibration method and device |
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