CN1789201A - Boron-containing graphite and its preparation method - Google Patents
Boron-containing graphite and its preparation method Download PDFInfo
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- CN1789201A CN1789201A CN 200410093183 CN200410093183A CN1789201A CN 1789201 A CN1789201 A CN 1789201A CN 200410093183 CN200410093183 CN 200410093183 CN 200410093183 A CN200410093183 A CN 200410093183A CN 1789201 A CN1789201 A CN 1789201A
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Abstract
The invention discloses a boron-containing black lead and its preparing method, which employs coking carbon as raw material, batch adding boron carbide for dry mixing, adding mesothermal asphalt for wet mixing, through processes of profiling, roasting, dipping and graphitizing to get the boron-containing black lead with boron content more than 4% and adequate distribution, which meets the criterion through forecasting and analysis.
Description
Technical field
The present invention relates to nuclear graphite and make technical field of producing, more particularly is a kind of borated graphite and its production technique.
Background technology
Nuclear reactor uses borated graphite to play the effect that the absorption nuclear reaction produces neutron in nuclear process, and its boron content and homogeneity thereof are the keys of this effect of performance.Borated graphite be except that possessing general nuclear graphite about the graphite material technical requirements such as volume density, resistivity, intensity, ash, thermal expansivity, thermal conductivity, especially boron content and distributing homogeneity thereof had the requirement of special strictness.Produce general synthetic graphite material, need carry out through the high temperature graphitization process more than 2500 ℃, and this temperature is much higher than the effusion temperature of boron, therefore adopt the general technology technology to be difficult to guarantee the boron content's index standard of finished product.
China is since the development and production sixties in last century nuclear graphite.The development and production of nuclear graphite, the domestic borated graphite that never carries out is developed, Chinese nuclear power research institute in 2002, quote and use for reference the borated graphite technical qualification of USSR (Union of Soviet Socialist Republics), worked out domestic borated graphite physical and chemical index, according to this index system, according to CEFR01207ZHC01-JT " the cleaning technique condition of China Experiment Fast Reactor fluid system and associated components ", GB7427-78 " carbon materials sampling method ", GB1429-85 standard-requireds such as " graphite material the ash content of coal measuring methods ", develop and produced the nuclear graphite borated graphite.Improve by production technology of the present invention, the boron content's index of guaranteeing borated graphite reaches standard-required and it is evenly distributed through complicated production process.The boron content's index detects by chemical analysis (GB9255-88) or the detection of plasma emission spectroscopy method and reaches standard-required.Product Acceptance Review is taked seedbed checking examination mode according to the regulation of nuclear safety codes HAF0403.
Summary of the invention
The purpose of this invention is to provide a kind of borated graphite.
Another object of the present invention provides a kind of production technique of borated graphite.
Borated graphite content provided by the invention and physicochemical property are as follows:
| Project | B content (%) weight ratio | Volume density g/cm 3 | Folding strength MPa | Tensile strength MPa | Ultimate compression strength MPa | Thermal expansivity * 10 6/℃ | Elastic modulus G Pa | Thermal conductivity W/M.K | Cl content PPm | |
| Index | ≥4 | ≥1.60 | ≥8 | ≥ 5.5 | ≥25 | ≤4 | ≤6 | ≤16 | ≥35 | ≤100 |
Borated graphite physicochemical property reference index
| Project | Processibility | Degree of graphitization (%) | Ash (%) (disregarding B content) | Foreign matter content PPM | |||||
| Fe | Si | Al | Ca | Mg | S | ||||
| Index | Good | ≥70 | ≤0.5 | ≤ 600 | ≤ 20 | ≤ 3 | ≤ 150 | ≤ 30 | ≤ 500 |
The borated graphite surface quality is
Product surface does not speckle with metal, nonmetal and oily foreign material, product surface non-scale.
The pitted skin defective allows to exist a place in being not more than 1/3 length range.
Allow width less than 0.1mm, length is less than 40mm crackle one place.
Hole defect allows hole (or equal-volume) three places of 4mm * 4mm * 4mm.
Only allow seamed edge to have 5mm * 5mm * 10mm to fall piece one place.
Product end surface does not allow crackle and exists.
Can not there be two kinds in above-mentioned defective simultaneously on a product.
Surfaceness is Ra3.2.
Borated graphite processing form and position tolerance
The cylinder linearity is not more than 1mm/1000mm.
Verticality is not more than 0.08mm.
Circularity is not more than 0.05mm.
The both ends of the surface planeness is not more than 0.06mm.
Length tolerance is not more than ± 1mm.
Diameter tolerance is not more than ± 0.3mm.
The present invention implements like this
The production technique of borated graphite following (seeing also accompanying drawing 1):
Synthetic graphite grain and mid-temperature pitch are as raw material of the present invention, and their technical requirements is:
The technical requirements of synthetic graphite grain is:
| Ash content, % | Volatile matter, % | Moisture, % | Sulphur content, % |
| ≤0.5 | ≤0.3 | ≤0.5 | ≤0.05 |
Binder pitch adopts mid-temperature pitch, and its technical requirements is as follows:
| Softening temperature, ℃ | Toluene insolubles, % | Ash content, % | Moisture, % | Volatile matter, % |
| 80-90 | 15-25 | ≤0.3 | ≤0.3 | 58-68 |
Annotate: pitch must can use after removing mechanical inclusion through dehydration, precipitation.
Synthetic graphite grain each grade synthetic graphite granularity behind fragmentation, abrasive dust is:
| Title | Granularity, mm | Purity, % | |
| The synthetic graphite grain | 2-1 | +1 | ＞75 |
| The synthetic graphite grain | 1-0.5 | +0.5 | ＞70 |
| The synthetic graphite grain | 0.5-0 | +0.15 | ＞65 (references) |
| Graphous graphite powder | 0.075 | -0.075 | 75±5 |
Siccative size composition is
| Mm | +2 | -2+1 | -1+0.5 | -0.075 |
| The % weight percent meter | ≤2 | 10±2 | 12±2 | 30±2 |
Size fractionated synthetic graphite grain is prepared burden by siccative size composition requirement, and the mixed pot of pinching of the siccative input for preparing is done mixed.Add mid-temperature pitch (softening temperature 80-90 ℃) beginning wet mixing in proportion after doing mixed the end.The synthetic graphite grain with in to mix the bituminous ratio be (weight percent): synthetic graphite grain (2-0mm) 71% ± 1%, in mixed pitch 29 ± 1%.
Sneak out in the journey gradation and add norbide dried, the norbide total addition level is 6.1% of a thickener total amount.Do to mix that norbide is evenly distributed in the synthetic graphite grain, norbide interpolation end back continued to do mixed 10-15 minute usually.
Set every pot of thickener total amount, mix and to pinch processing parameter and be controlled at:
| Stirrer | Heating agent design temperature ℃ | The dried min that does time | Siccative temperature ℃ | Wet mixing time min | Thickener temperature ℃ |
| 2000L | 180±5 | 45～50 | 105±5 | 45～50 | 145±5 |
Mix the thickener pinch after the end and be cooled to assigned temperature (material temperature): 105-120 ℃ through the drum type brake cooler.Cool good thickener divides two batches to add the pan feeding cylinder.
The die mould processing parameter:
| Preload pressure Mpa | Dwell time min | Extrusion speed Sec/m | Vacuum tightness Mpa |
| 19.6 | ≤0.3 | ≮0.5 | -0.05 |
Carry out roasting after the moulding, after before the shove charge stopping composition and furnace equipment being checked, carry out the shove charge operation.Stopping composition is a metallurgical coke, and its granularity is 6-0mm, moisture ≯ 3%, use temperature ≯ 60 ℃.
The roasting ignition temperature is 350 ℃, is pre-heating stage before this.Then do not limit when igniting furnace chamber temperature is not 350 ℃ above assigned temperature; Be lower than assigned temperature as actual temperature, then the igniting back is by ≯ 40 ℃ of/class intensifications, until catching up with assigned temperature.
In the temperature-rise period, descend, can rise to original temperature by this stage triple speed degree during recovery owing to reasons such as stopping coal gas, power failure makes temperature, because heating up, other reasons do not reach regulation plan temperature, can be with the temperature rise temperature, require to be:＜1000 ℃, 10 ℃ of per tour band temperature;＞1000 ℃, 20 ℃ of per tour band temperature.
Cool off, come out of the stove
After ceasing fire, taking off lid, furnace chamber naturally cooling, and progressively grab and cover material, product temperature is not more than 400 ℃ (the made-up article surface is not rubescent) when guaranteeing to come out of the stove.
Product answers layering, distribution box to be placed on place cleaning and to clear up, and product surface and end face must be cleaned out.
The roast base must and knock differentiation through observation check, and identifies on request, stacks.
Roasting base sampling analysis
Roasting is carried out sampling analysis to the roasting base after finishing.
Quantity of sampling quantity: ≮ 2, can choose the waste product sampling analysis if any waste product.
Sample position: at top, middle part, the bottom difference sampling analysis of sampling made-up article.
Physical and chemical index: volume density ≮ 1.60g/cm
2, boron content (weight ratio) ≮ 4%, ultimate compression strength ≮ 30MPa.
Density, intensity do not reach These parameters, need flood, re-baking handles.
Roasting is carried out low temperature graphitization after finishing, and the combustion chamber temperature is not higher than 2000 ℃, and whole temperature is not less than 1800 ℃.
The technical requirements of greying furnace charge
| The furnace charge title | Material | Specification mm | Volatile matter % | Ash content % | Moisture % | Sulphur content % | True density g/cm 3 |
| Furnace burdening | Carbon black | Granular | ≯1.0 | ≯1.0 | ≯1.0 | - | - |
| Insulation material | The oil breeze | 0.5～0 | ≯1.0 | ≯1.0 | ≯1.0 | ≯0.6 | ≮2.01 |
| Resistance material | Forge the back pitch coke | 20～10 | ≯1.0 | ≯1.0 | ≯0.5 | ≯0.6 | ≮2.00 |
| Last bed course | The greying pitch coke | 20～10 | ≯1.0 | ≯1.0 | ≯0.5 | - | - |
| 10～5 | ≯1.0 | ≯1.0 | ≯0.5 | - | - | ||
| Underlayer | Forge the back pitch coke | 20～10 | ≯1.0 | ≯1.0 | ≯0.5 | ≯1.0 | ≮2.00 |
The graphitizing furnace energising heating of packing into of above-mentioned furnace charge is risen furnace temperature gradually, and the combustion chamber temperature reaches 1900 ℃, and it is electricity cut-off standard that the combustion chamber temperature reaches requirement.Cooling off total cooling time is 400-500 hour, and the made-up article temperature can be come out of the stove less than 400 ℃ and be carried out physical and chemical performance analysis.
The product physical and chemical index is by analysis:
| Project | B content (%) weight ratio | Volume density g/cm 3 | Folding strength MPa | Tensile strength MPa | Ultimate compression strength MPa | Thermal expansivity * 10 -6/℃ | Elastic modulus G Pa | Thermal conductivity W/M.K | Cl content PPm | |
| Index | ≥4 | ≥1.60 | ≥8 | ≥5.5 | ≥25 | ≤4 | ≤6 | ≤16 | ≥35 | ≤100 |
| Project | Processibility | Degree of graphitization (%) | Ash (%) (disregarding B content) | Foreign matter content PPM | |||||
| Fe | Si | Al | Ca | Mg | S | ||||
| Index | Good | ≥70 | ≤0.5 | ≤ 600 | ≤ 20 | ≤ 3 | ≤ 150 | ≤ 30 | ≤ 500 |
Made-up article through the being up to the standards borated graphite that is machined into a certain size
Description of drawings
Fig. 1: the production technique figure of borated graphite
Embodiment
Below in conjunction with specific embodiment the present invention is further described, but does not limit the present invention.
1. determine that the thickener gross weight is 1800kg.By this thickener gross weight, prepare norbide 110kg (account for thickener gross weight 6.1%).
2. take by weighing synthetic graphite grain 1200kg, siccative size composition is:
| Mm | +2 | -2+1 | -1+0.5 | -0.075 |
| The % weight percent meter | ≤2 | 10±2 | 12±2 | 30±2 |
Pack in the kneading machine, start is done and is mixed.The dried portion-wise addition norbide 110kg altogether that sneaks out in the journey.Dried doing time is 45 minutes.
3. after doing mixed the end, once add mid-temperature pitch 490kg, the beginning wet mixing, the wet mixing time is 50 minutes.
4. the thickener after wet mixing being finished is poured cooler into and is begun cool material, finishes cool material after the thickener temperature reaches 105-120 ℃.
5. the thickener that cold is good adds press material cylinder.
6. paste extruded is become diameter 175mm, the blank that is uneven in length is called green compact.
7. green compact are adorned as stoving oven, and the metallurgical coke that adopts 6-0mm begins to add thermal bake-out as stopping composition.Maturing temperature arrives 1250 ℃ of follow-up continuation of insurance temperature and stops heating after 20 hours.
8. the roasting base of cooling after coming out of the stove needs dress watch, and sampling analysis volume density, ultimate compression strength, boron content.
9. the graphitizing furnace of qualified roasting base being packed into begins to heat greying.Graphitization temperature is controlled at the combustion chamber temperature and is no more than 2000 ℃, and whole temperature is not less than 1800 ℃.
10. the greying base behind the cooling place stove needs dress watch, and sampling carries out analyzing and testing by every physical and chemical index of borated graphite, transfers manufacturing procedure after reaching requirement.
11. surface quality requirement and processing Geometrical Tolerance Principle by borated graphite are processed.
12., obtain qualified borated graphite through above each step.
Claims (8)
1, a kind of graphite contains 〉=borated graphite of 4% boron by weight percentage, and has following physico-chemical property:
Project B content (%) weight ratio Volume density g/cm
3 Folding strength MPa Tensile strength MPa Ultimate compression strength MPa Thermal expansivity * 10
-6/℃
Elastic modulus G Pa Thermal conductivity W/M.K Cl content PPm
Index ≥4 ≥1.60 ≥8 ≥5.5 ≥25 ≤4 ≤6 ≤16 ≥35 ≤100
Project Processibility Degree of graphitization (%) Ash (%) (disregarding B content) Foreign matter content PPM
Fe Si Al Ca Mg S
Index Good ≥70 ≤0.5 ≤ 600 ≤ 20 ≤ 3 ≤ 150 ≤ 30 ≤ 500
2, borated graphite according to claim 1 is characterized in that boron content (by weight percentage) is 〉=4% in the borated graphite, and it is evenly distributed in the graphite.
3, the production technique of borated graphite as claimed in claim 1 is fragmentation, abrasive dust in the synthetic graphite warp, prepares burden by the siccative granularity, the siccative input for preparing is mixed to pinch to do and is mixed and gradation adds norbide and does and add mid-temperature pitch in proportion after mixed and carry out wet mixing, cool material, die mould after the wet mixing, carry out roasting behind the die mould, qualified roasting base carries out greying, and greying is after the cooler processed finished products.
4, production technique according to claim 3 is characterized in that in percent by weight synthetic graphite grain: mid-temperature pitch=71% ± 1%: 29% ± 1%.
5, production technique according to claim 3 is characterized in that in the synthetic graphite particle diameter that each grade synthetic graphite granularity is behind the comminution powder:
Title Granularity, mm Purity, %
The synthetic graphite grain 2-1 +1 ＞75
The synthetic graphite grain 1-0.5 +0.5 ＞70
The synthetic graphite grain 0.5-0 +0.15 ＞65 (references)
Graphous graphite powder 0.075 -0.075 75±5
Siccative size composition is
Mm +2 -2+1 -1+0.5 -0.075
The % weight percent meter ≤2 10±2 12±2 30±2
6, production technique according to claim 3 is characterized in that the gradation adding is done mixed with Graphite Powder 99 when adding norbide.
7, borated graphite according to claim 2 is characterized in that binder pitch adopts mid-temperature pitch, and its softening temperature is:
Softening temperature, ℃ Toluene insolubles, % Ash content, % Moisture, % Volatile matter, %
80-90 15-25 ≤0.3 ≤0.3 58-68
8, borated graphite production technique according to claim 3, the combustion chamber temperature is less than 2000 ℃, greater than 1800 ℃ when it is characterized in that greying.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 200410093183 CN1789201A (en) | 2004-12-17 | 2004-12-17 | Boron-containing graphite and its preparation method |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 200410093183 CN1789201A (en) | 2004-12-17 | 2004-12-17 | Boron-containing graphite and its preparation method |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101450864B (en) * | 2007-12-07 | 2011-05-11 | 中国科学院金属研究所 | Heat treating method of carbon-boron material |
| CN101450865B (en) * | 2007-12-07 | 2011-08-10 | 中国科学院金属研究所 | Heat treating method of carbon graphite material |
| CN108584906A (en) * | 2018-05-29 | 2018-09-28 | 方大炭素新材料科技股份有限公司 | A method of selection and judgement isotropism or near-isotropic raw material are burnt |
| CN109336601A (en) * | 2018-09-19 | 2019-02-15 | 中钢集团新型材料（浙江）有限公司 | A method of with multistage uniform kneading system production borated graphite |
-
2004
- 2004-12-17 CN CN 200410093183 patent/CN1789201A/en active Pending
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101450864B (en) * | 2007-12-07 | 2011-05-11 | 中国科学院金属研究所 | Heat treating method of carbon-boron material |
| CN101450865B (en) * | 2007-12-07 | 2011-08-10 | 中国科学院金属研究所 | Heat treating method of carbon graphite material |
| CN108584906A (en) * | 2018-05-29 | 2018-09-28 | 方大炭素新材料科技股份有限公司 | A method of selection and judgement isotropism or near-isotropic raw material are burnt |
| CN109336601A (en) * | 2018-09-19 | 2019-02-15 | 中钢集团新型材料（浙江）有限公司 | A method of with multistage uniform kneading system production borated graphite |
| CN109336601B (en) * | 2018-09-19 | 2021-06-08 | 中钢新型材料股份有限公司 | Method for producing boron-containing graphite by using multistage uniform kneading system |
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