CN103017916B - Novel high-temperature erosion-resistant thermocouple protection sleeve and production method thereof - Google Patents
Novel high-temperature erosion-resistant thermocouple protection sleeve and production method thereof Download PDFInfo
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- CN103017916B CN103017916B CN201210517788.4A CN201210517788A CN103017916B CN 103017916 B CN103017916 B CN 103017916B CN 201210517788 A CN201210517788 A CN 201210517788A CN 103017916 B CN103017916 B CN 103017916B
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Abstract
The invention discloses a novel high-temperature erosion-resistant thermocouple protection sleeve and a production method thereof. The production method is characterized in that austenitic stainless steel is adopted as a base body, an AlFeNi composite coating layer with atomic ratio to be 3:1:1 is sprayed on the workpiece surface, heat preservation is carried out in a temperature range of 670-700 DEG C for 0.5-1h, then the temperature rises to 950-1000 DEG C and is kept for 3-4h, the workpiece surface is cooled to be at 300 DEG C along with a furnace and taken out for air cooling, and accordingly a FeAl intermetallic compound one-phase coating of a B2 structure and attached onto the surface of the base body of the austenitic stainless steel thermocouple protection sleeve is obtained. The B2-FeAl intermetallic compound coating with orientated growth characteristic columnar crystals is obtained on the surface of the austenitic stainless steel thermocouple protection sleeve so that the high temperature performance, wear resistance and corrosion resistance of the thermocouple protection sleeve are greatly improved, and the thermocouple protection sleeve is especially applicable to surface protection of the temperature measuring thermocouple used by a circulating fluidized bed boiler.
Description
Technical field
The present invention relates to a kind of new type high temperature Anti-erosion thermocouple protective casing technology of preparing, mainly for the thermocouple protective casing using under the high temperature erosion atmosphere such as circulating fluidized bed boiler.
Background technology
In power industry, in Circulating Fluidized Bed Boiler, temperature thermocouple is widely applied.Working environment due to complicated in stove, has proposed specific (special) requirements to thermocouple protective casing, i.e. wear-resisting, high temperature resistant, resistance to erosion, corrosion-resistant.Due to measurement point excess Temperature in stove, and contain macro-corrosion performance gas, in stove, a large amount of fuel particles play erosive wear and corrosive attack to thermopair, and the loss of thermocouple protective casing surfacing is serious, and serviceable life is shorter.Traditional stainless steel protection sleeve pipe, as 1Cr18Ni9Ti, 0Cr25Ni20 sleeve pipe etc., preparation cost is low, and heat-resisting quantity can meet the demands, but high temperature resistance erosion scarce capacity.In Circulating Fluidized Bed Boiler, apply, be only 30-90 days serviceable life, and the long-term safety operation of boiler is had to considerable influence.
Traditional stainless steel thermocouple protective casing preparation technology is simple, the stainless-steel tube of selection standard specification, and the length that intercepting needs, end solder up then, production cost is low.When this class protective casing is applied under rugged surroundings in Circulating Fluidized Bed Boiler, failure site mainly contains two regions: the one, and end welding region, institutional framework is significantly different from other positions of thermocouple protective casing, is the position of the most easily losing efficacy; Be exactly the interface of thermocouple protective casing and boiler inner wall in addition, because of the change of this region wind flow direction, very serious to the erosive wear of thermocouple protective casing.Exploitation is suitable for the high temperature Anti-erosion technology of thermocouple protective casing, improves the high temperature erosion resistance of thermocouple protective casing, to extending the serviceable life of thermopair, realizes the long-term safety operation of Circulating Fluidized Bed Boiler, significant.
Summary of the invention
The invention provides a kind of new type high temperature Anti-erosion thermocouple protective casing and preparation technology thereof, increased substantially high temperature wearable anti-corrosion ability, be particularly useful for the surfacecti proteon of temperature thermocouple for Circulating Fluidized Bed Boiler.
For achieving the above object; high temperature Anti-erosion thermocouple protective casing of the present invention; it is the single-phase coating of FeAl intermetallic compound with one deck B2 structure at austenitic stainless steel thermocouple protective casing matrix surface; this intermetallic compound coating is oriented growth feature column crystal B2-FeAl intermetallic compound coating, and average hardness reaches 870HV.
High temperature Anti-erosion thermocouple protective casing preparation method of the present invention is as follows:
Select austenitic stainless steel as matrix, the AlFeNi composite coating that is 3:1:1 at workpiece surface spraying one deck atomic ratio is then incubated 0.5-1 hour under 670 ℃ of-700 ℃ of temperature ranges, be warming up to 950 ℃-1000 ℃, insulation 3-4 hour, then cools to 300 ℃ with the furnace, takes out air cooling.
Detailed preparation method is as follows for high temperature Anti-erosion thermocouple protective casing of the present invention:
The first step: the raw-material preparation of coating
By purity >=99.0%, pure Al powder, Fe powder and the Ni powder of particle size range 53-74 μ m mixes according to the ratio of atomic ratio 3:1:1, puts into bowl mill ball-milling treatment, and drum's speed of rotation is 400r/min, and Ball-milling Time is 10-30min.
By the powder sieving after ball milling, choosing granularity is that 30-61 μ mFe-Al-Ni composite powder is as coating starting material, for spraying.
Second step: prefabricated coating
Select austenitic stainless steel protective casing as matrix; conventional material has 1Cr18Ni9Ti, 0Cr25Ni20 etc.; surface sand-blasting purifies; adopt high energy plasma spraying equipment or HVOF equipment to spray to thermocouple protective casing surface Fe-Al-Ni composite powder, coating thickness is designed to 0.5mm-1mm.
The 3rd step: coating thermal treatment
(1) thermocouple protective casing of prefabricated coating is put into common high-temperature electric resistance furnace, be warmed up to 670 ℃-700 ℃, insulation 0.5-1 hour.In this course, the Al fusing in coating, and generate the intermetallic compounds such as FeAl3, NiAl with Fe, Ni element reaction.
(2) continue to be warmed up to 950 ℃-1000 ℃, insulation 3-4 hour, then cools to 300 ℃ with the furnace, takes out air cooling.In this course, in coating, Al element spreads to matrix, and the Fe element in stainless steel base is to external diffusion, and under the high temperature of interface, induced chemical reaction generates B2-FeAl intermetallic compound, and constantly grows along the direction perpendicular to interface.Under the effect of High temperature diffusion, in coating, dissolve in a large amount of Ni, Cr alloying element simultaneously, improved obdurability and the high-temperature oxidation resistance of coating.Coating average microhardness has reached 870HV, and high temperature resistance erosion property is excellent.
The good effect of this invention is:
(1) the present invention obtains a kind of oriented growth feature column crystal B2-FeAl intermetallic compound coating that has on austenitic stainless steel thermocouple protective casing surface; increase substantially high temperature wearable anti-corrosion ability, be particularly useful for the surfacecti proteon of temperature thermocouple for Circulating Fluidized Bed Boiler.
(2) through check; B2-FeAl intermetallic compound coating dense structure on protective casing matrix of the present invention; average microhardness is up to 870HV; and the alloying action by means of Ni, Cr element; reduced coating fragility; improved coating obdurability and antioxygenic property, coating has excellent high temperature erosion wear resistance.
(3) adopting B2-FeAl intermetallic compound prepared by the method is single-phase layer structure, and along the column crystal of the direction oriented growth formative tissue even structure perpendicular to matrix surface, has excellent electrochemically resistant and learn corrosion and high-temperature salt-resistant corrosive nature.
(4) owing to having added a certain proportion of Ni element in coating starting material, in follow-up heat treatment process, avoid the Ni unit procatarxis concentration gradient in stainless steel base large to coating transition diffusion, when obtaining high-performance coating, kept the high temperature obdurability that former stainless steel material is good.
(5) the method has significantly improved the high temperature anti-erosion property of thermocouple protective casing, and coating is FeAl intermetallic compound, and thermal conductivity is good, and responsive to temperature variation, thermocouple temperature measurement precision is high.
Accompanying drawing explanation
Fig. 1 is the high temperature Anti-erosion thermocouple protective casing structural representation of coating protection.
Fig. 2 is the tissue topography of coating under light microscopic, wherein: Fig. 2 a be coating in 200X light microscopic lower surface tissue topography, Fig. 2 b is that coating is in 200X light microscopic lower section tissue topography.
In figure: 1-matrix, 2-coating.
Embodiment
As shown in Figure 1; protective casing of the present invention is the single-phase coating 2 of FeAl intermetallic compound with one deck B2 structure on austenitic stainless steel thermocouple protective casing matrix 1 surface, and this intermetallic compound coating 2 is oriented growth feature column crystal B2-FeAl intermetallic compound coating.From Fig. 2 a and Fig. 2 b, can find out, coating 2 is typical columnar crystal structure, and coating structure is more even.
With a specific embodiment, describe preparation method of the present invention in detail below, not as limiting the scope of the invention.
The first step, select purity >=99.0%, pure Al powder 1.6kg, Fe powder 1.1kg and the Ni powder 1.2kg of granularity 70 μ m left and right mix (being similar to atomic ratio 3:1:1), put into bowl mill ball milling 20 minutes, and drum's speed of rotation is 400r/min.By the powder sieving after ball milling, choose granularity and be 30-61 μ mFe-Al-Ni composite powder as coating starting material, put into 120 ℃ of bakings of baking oven 1.5 hours, for spraying.
Second step, select the 0Cr25Ni20 stainless steel thermocouple protective casing of long 0.8 meter of external diameter φ 25, surface degreasing, with 20 object corundum sand sandblasts purifications, air pressure is 0.5MPa.
The 3rd step, pack powder feeder into after will self-control Fe-Al-Ni composite powder drying, and adopt high energy plasma spraying equipment to spray to thermocouple protective casing surface, coating thickness is 0.5mm left and right.
The 4th step, the thermocouple protective casing of coating is kept flat in resistance furnace, be warmed up to 700 ℃, be incubated 0.5 hour.
The 5th step, continue to be warming up to 950 ℃, be incubated 4 hours, then, with slow cold the going to 300 ℃ of stove, take out air cooling.
Claims (1)
1. a new type high temperature Anti-erosion thermocouple protective casing, it is characterized in that, it is with the single-phase coating of one deck B2-FeAl intermetallic compound at austenitic stainless steel thermocouple protective casing matrix surface, this intermetallic compound coating is oriented growth feature column crystal B2-FeAl intermetallic compound coating, and average hardness reaches 870HV; The preparation method of this high temperature Anti-erosion thermocouple protective casing is:
The first step: the raw-material preparation of coating
By purity >=99.0%, pure Al powder, Fe powder and the Ni powder of particle size range 53-74 μ m mixes according to the ratio of atomic ratio 3:1:1, puts into bowl mill ball-milling treatment, and drum's speed of rotation is 400r/min, and Ball-milling Time is 10-30min;
By the powder sieving after ball milling, choosing granularity is that 30-61 μ mFe-Al-Ni composite powder is as coating starting material, for spraying;
Second step: prefabricated coating
Select austenitic stainless steel thermocouple protective casing as matrix, surface sand-blasting purifies, adopt high energy plasma spraying equipment or HVOF equipment to spray to thermocouple protective casing surface Fe-Al-Ni composite powder, coating thickness is designed to 0.5mm-1mm;
The 3rd step: coating thermal treatment
(1) thermocouple protective casing of prefabricated coating is put into common high-temperature electric resistance furnace, be warmed up to 670 ℃-700 ℃, insulation 0.5-1 hour;
(2) continue to be warmed up to 950 ℃-1000 ℃, insulation 3-4 hour, then cools to 300 ℃ with the furnace, takes out air cooling.
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| CN201210517788.4A CN103017916B (en) | 2012-12-05 | 2012-12-05 | Novel high-temperature erosion-resistant thermocouple protection sleeve and production method thereof |
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| CN201210517788.4A CN103017916B (en) | 2012-12-05 | 2012-12-05 | Novel high-temperature erosion-resistant thermocouple protection sleeve and production method thereof |
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| CN108907204B (en) * | 2018-07-30 | 2020-01-31 | 株洲新陶新材料有限公司 | kinds of Al2O3Preparation process of-Cr high-temperature structural ceramic thermocouple protection sleeve |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN201622129U (en) * | 2009-08-31 | 2010-11-03 | 上海恒洋仪表科技有限公司 | Special-purpose thermoelectric couple for burning garbage |
| CN102057262A (en) * | 2008-06-10 | 2011-05-11 | 贺利氏电子耐特国际股份公司 | Protective cover for a sensor in aluminium melts |
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| JPH08292105A (en) * | 1995-04-21 | 1996-11-05 | Furukawa Electric Co Ltd:The | Protective tube for thermocouple |
| JP5399291B2 (en) * | 2010-02-19 | 2014-01-29 | 東京窯業株式会社 | Temperature measuring probe |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102057262A (en) * | 2008-06-10 | 2011-05-11 | 贺利氏电子耐特国际股份公司 | Protective cover for a sensor in aluminium melts |
| CN201622129U (en) * | 2009-08-31 | 2010-11-03 | 上海恒洋仪表科技有限公司 | Special-purpose thermoelectric couple for burning garbage |
Non-Patent Citations (4)
| Title |
|---|
| B2型FeAl金属间化合物的制备及性能研究进展;宋海霞 等;《粉末冶金技术》;20071231;第27卷(第5期);第1栏第1段、第382页第1栏第4段、第383页第1栏第5段 * |
| JP特开2011-169798A 2011.09.01 |
| JP特开平8-292105A 1996.11.05 |
| 宋海霞 等.B2型FeAl金属间化合物的制备及性能研究进展.《粉末冶金技术》.2007,第27卷(第5期),第1栏第1段、第382页第1栏第4段、第383页第1栏第5段. |
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