CN111118443A - Method for preparing metal ceramic coating on austenitic stainless steel surface - Google Patents
Method for preparing metal ceramic coating on austenitic stainless steel surface Download PDFInfo
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- CN111118443A CN111118443A CN201911301039.6A CN201911301039A CN111118443A CN 111118443 A CN111118443 A CN 111118443A CN 201911301039 A CN201911301039 A CN 201911301039A CN 111118443 A CN111118443 A CN 111118443A
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C12/00—Solid state diffusion of at least one non-metal element other than silicon and at least one metal element or silicon into metallic material surfaces
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Abstract
The invention provides a method for preparing a metal ceramic coating on the surface of austenitic stainless steel, which comprises the following steps: the method comprises the steps of cleaning, drying, compacting, preheating, vacuum, heating up, carburizing and nitriding, heating up, chromizing, laser irradiation and the like, wherein a surface ceramic layer is formed by carburizing carbon, nitrogen and chromium on the surface of a workpiece under a high-temperature condition, and then a metal and ceramic mixed structure is formed by laser irradiation, so that the surface coating has the corrosion resistance of austenitic stainless steel and the high mechanical strength of the ceramic layer at the same time, the preparation method is simple, and the formed coating has excellent performance and good application prospect.
Description
Technical Field
The invention relates to the technical field of metal surface treatment, in particular to a method for preparing a metal ceramic coating on the surface of austenitic stainless steel.
Background
Austenitic stainless steel has good corrosion resistance and high temperature resistance, and is widely applied to various industrial fields. However, because austenitic stainless steel has low hardness and poor wear resistance, and the surface of austenitic stainless steel is easy to scratch and wear, the application of austenitic stainless steel is limited in some fields with high requirements on wear resistance, and domestic and foreign scholars have conducted various modification treatments and strengthening researches on the surface of stainless steel for years, such as nitriding, carburizing, electroplating, chemical plating, vapor deposition, ion implantation, thermal spraying and the like, in order to improve the wear resistance of austenitic stainless steel.
Nitriding and carburizing are common technologies, carburizing is usually carried out at 890 ℃ in 850-600 ℃, nitriding is carried out at 600-500 ℃, carbide and nitride layers can be formed on the surface of the stainless steel, so that the hardness and the wear resistance are improved, but chromium carbide and chromium nitride are also produced in austenitic stainless steel under the temperature condition, so that the chromium element in the austenitic stainless steel is consumed, and the corrosion resistance of the austenitic stainless steel is greatly reduced.
Disclosure of Invention
In view of the above, the present invention provides a method for preparing a cermet coating on the surface of austenitic stainless steel, which can improve hardness and wear resistance without reducing corrosion resistance.
The technical scheme of the invention is realized as follows: the invention provides a method for preparing a metal ceramic coating on the surface of austenitic stainless steel, which comprises the following steps:
step one, placing a stainless steel product in an ultrasonic cleaning machine, cleaning for 5-10min, injecting deionized water into the ultrasonic cleaning machine, immersing the stainless steel product in the deionized water, and drying the stainless steel product by using high-pressure nitrogen after cleaning;
secondly, placing the dried stainless steel product in a vacuum chamber, embedding the stainless steel product by using coating powder, preferably, placing the stainless steel product in a high-temperature resistant container, filling the coating powder in the container, embedding the stainless steel product in the coating powder, and compacting the coating powder by using a vibration compaction machine for 1-2 min;
step three, heating the vacuum chamber to 200 ℃, introducing reaction gas for replacement after vacuumizing, and vacuumizing until the pressure in the vacuum chamber is not more than 10 Kpa;
step four, after the reaction gas replacement is finished, heating the vacuum chamber to 800 ℃ and preserving the heat for 5-10 h;
step five, after the heat preservation reaction in the step four is finished, heating the vacuum chamber to 900-;
and step six, after the heat preservation reaction in the step five is finished, after the vacuum chamber is cooled to the room temperature, taking out the stainless steel product, putting the stainless steel product into a laser irradiation chamber, replacing gas in the laser irradiation chamber by using protective gas, and after the replacement is finished, irradiating the surface of the stainless steel product by using laser beams.
On the basis of the above technical solution, preferably, the coating powder comprises the following components in parts by mass: supplying a chromium agent: penetration enhancer: filler (10-22): (40-60): (1-5): (30-45).
On the basis of the above technical solution, preferably, the carbon-nitrogen supplying agent is solid organic powder.
On the basis of the technical scheme, preferably, the solid organic matter is one or a mixture of more of polyvinyl chloride, polytetrafluoroethylene and melamine.
On the basis of the technical scheme, preferably, the chromium supply agent is one or a mixture of more of metal chromium powder, chromium iron powder and chromium sesquioxide.
Still further preferably, the penetration enhancer is a halogen ammonium salt.
On the basis of the technical scheme, preferably, the penetration enhancer is one or a mixture of ammonium chloride, ammonium fluoride and ammonium iodide.
On the basis of the technical scheme, preferably, the filler is one or a mixture of more of calcined alumina, bauxite and kaolin.
On the basis of the above technical scheme, preferably, in the third step, the reaction gas includes ammonia gas and one or more of nitrogen gas, hydrogen gas, carbon monoxide and carbon dioxide.
On the basis of the above technical solution, preferably, in step six, the irradiation power of the laser beam is 2 to 10kW, the scanning speed of the laser beam is 5 to 8mm/s, and the spot diameter of the laser beam is 2 to 5 mm.
In the technical scheme, when the temperature is raised to 600-800 ℃, the coating powder is heated and decomposed to release active carbon atoms and nitrogen atoms, and the two active atoms are diffused and infiltrated into the surface of the austenitic stainless steel product at the temperature, so that a carbon-rich layer and a nitrogen-rich layer are formed; when the temperature is further increased to 900-1000 ℃, the coating powder further decomposes active chromium atoms, the chromium atoms permeate into the surface of the austenitic stainless steel, and reacts with the carbon-rich layer and the nitrogen-rich layer to form chromium carbide and chromium nitride cermets, whereas the ceramic layers formed are relatively independent, although having good hardness, the corrosion resistance is relatively poor, and therefore, with the laser irradiation treatment, a local melting zone is quickly formed through laser irradiation, so that the cermet layer on the outer layer and the austenitic stainless steel on the inner side are mutually mixed and dissolved to form a mixed layer, the cermet layer provides good mechanical property, meanwhile, the austenitic stainless steel layer provides better corrosion resistance, and as a preferable scheme for laser beam irradiation, the laser beams adopt multiple scanning paths until the scanning paths are not contacted with each other, and gaps with the spot diameter of 1/3-1/2 are formed between the scanning paths.
Compared with the prior art, the method for preparing the metal ceramic coating on the surface of the austenitic stainless steel has the following beneficial effects:
(1) the method for preparing the metal ceramic coating on the surface of the austenitic stainless steel overcomes the problem of reducing the corrosivity caused by conventional surface hardening treatment, a high-carbon-nitrogen ceramic layer is attached to the surface of a workpiece by utilizing the permeation of a high-temperature ion atmosphere, and then the surface is subjected to hot melting treatment by utilizing a laser beam, so that the internal metal and the ceramic layer on the surface form a structural cover plate to form a staggered ceramic and metal structural layer, and the surface coating simultaneously has the corrosion resistance of the austenitic stainless steel and the mechanical property of the ceramic layer;
(2) the coating method is simple to operate, the used raw materials can be recycled, and the surface of the formed workpiece has good appearance and mechanical properties and good application prospect.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.
Example 1
Stainless steel small shaft made of 316Ti and having size
The weight of each piece is about 6.5g, and the surface is required to be hardThe degree is not less than 950HV0.05, the depth of a hardening layer is 15-35 mu m, and the working environment is a turbocharger combustion chamber. Carrying out surface hardening and infiltration treatment on the small shaft according to the following steps:
weighing 75g of polyvinyl chloride powder, 125g of melamine powder, 450g of chromium powder, 350g of ferrochrome powder, 100g of ammonium chloride and 900g of aluminum oxide powder, putting into a mixer, fully stirring for 5min, and uniformly mixing for later use;
taking 200 stainless steel small shafts, putting the stainless steel small shafts into an ultrasonic cleaning machine filled with deionized water, cleaning for 5min, and drying by using nitrogen after cleaning;
mixing the dried stainless steel small shaft with the uniformly mixed coating powder, putting into an iron barrel, and putting the iron barrel on a vibration compaction table for compaction for 1 min;
after the compaction is finished, covering and pressing the iron bucket, putting the iron bucket into a vacuum chamber, heating the vacuum chamber to 200 ℃, simultaneously vacuumizing the vacuum chamber until the internal pressure is not more than 10Kpa, introducing a mixed gas of ammonia and nitrogen into the vacuum chamber for replacement for 5min, and keeping the ammonia pipeline unblocked after the replacement is finished;
heating the vacuum chamber to 600 ℃, preserving heat for 5h, continuously heating to 900 ℃ after heat preservation, and preserving heat for 5 h;
after heat preservation is finished, the temperature is reduced to room temperature, the iron bucket is taken out, the stainless steel small shaft inside is taken out, nitrogen is used for blowing away residual coating powder on the surface of the stainless steel small shaft, the stainless steel small shaft is placed into a laser irradiation chamber, nitrogen is used for carrying out gas replacement on the inside of the laser irradiation chamber for 5min, 2kw of CO2 laser is used for carrying out laser irradiation on the surface of the stainless steel small shaft, the diameter of a light spot of a laser beam is 2mm, the scanning speed of the laser beam is 5mm/s, the interval between every two adjacent scanning tracks is 1mm, and after scanning is finished, the stainless steel small shaft with the surface covered with a metal ceramic coating is obtained.
After the treatment steps, the pin shaft represents a silver gray chromium compound metal ceramic hardened layer, the thickness of the hardened layer is 18-25 mu m, and the hardness of the hardened layer is 1600-1850HV 0.05; the coating has the advantages of neutral salt spray resistance for 1000h, no rust mark on the surface, no change in color and luster, and no peeling and corrosion phenomena and no change in surface hardness due to a 900 ℃ high-temperature oxidation test for 20 h.
Example 2
The valve arm of the automobile engine combustion chamber, which is made of 310S (06Cr25Ni20), has the working temperature of not less than 900 ℃, the surface hardness after carburization of 1000HV0.05 and the actual service life of 10 kilometers, and is subjected to surface hardening and coating treatment by adopting the following steps:
weighing 1500g of melamine powder, 700g of polytetrafluoroethylene powder, 4700g of chromium oxide powder, 100g of ammonium fluoride powder and 3000g of bauxite powder, putting into a mixer, fully stirring for 5min, and uniformly mixing for later use;
placing the valve arm of the combustion chamber of the automobile engine into an ultrasonic cleaning machine filled with deionized water for cleaning for 10min, and drying by using nitrogen after cleaning;
mixing the dried valve arm of the automobile engine combustion chamber with the uniformly mixed coating powder, filling the mixture into an iron barrel, and putting the iron barrel on a vibration compaction table for 2 min;
after the compaction is finished, closing and pressing the iron bucket cover, putting the iron bucket cover into a vacuum chamber, heating the vacuum chamber to 200 ℃, simultaneously vacuumizing the vacuum chamber until the internal pressure is not more than 10Kpa, introducing mixed gas of ammonia, hydrogen and carbon monoxide into the vacuum chamber for replacement for 5min, and keeping an ammonia pipeline unblocked after the replacement is finished;
heating the vacuum chamber to 800 ℃, preserving heat for 10 hours, continuously heating to 1000 ℃ after heat preservation, and preserving heat for 10 hours;
after heat preservation is finished, cooling to room temperature, taking out the iron drum, taking out the valve arm of the automobile engine combustion chamber inside, blowing away residual coating powder on the surface of the valve arm by using nitrogen, putting the valve arm of the automobile engine combustion chamber into a laser irradiation chamber, performing gas replacement on the inside of the laser irradiation chamber by using argon for 5min, performing laser irradiation on the surface of a stainless steel small shaft by using a 10kw CO2 laser, wherein the diameter of a light spot of a laser beam is 5mm, the scanning speed of the laser beam is 8mm/s, the interval between two adjacent scanning tracks is 2mm, and obtaining the valve arm of the automobile engine combustion chamber with the surface covered with a metal ceramic coating after scanning is finished.
The surface of the valve arm of the automobile engine combustion chamber after the treatment forms a silvery white bright layer, a radial detection structure shows that the surface has a mutual doped structure of a white bright chromium compound layer and a carbon-rich single layer, the total thickness is about 40 mu m, the surface hardness reaches 1760-1850HV0.05 through detection, and the service life of the valve arm is prolonged to 40 ten thousand kilometers.
Example 3
The surface metal ceramic coating treatment is carried out on a valve ball and a valve seat which are made of 316L by adopting the following steps:
weighing 75g of polyvinyl chloride powder, 75g of melamine powder, 250g of chromium powder, 350g of ferrochrome powder, 30g of ammonium iodide and 400g of high alumina pottery clay powder, putting into a mixer, fully stirring for 5min, and uniformly mixing for later use;
placing the valve ball and the valve seat into an ultrasonic cleaning machine filled with deionized water for cleaning for 5min, and drying by using nitrogen after cleaning;
mixing the dried valve ball and valve seat with the uniformly mixed coating powder, filling into an iron barrel, and compacting the iron barrel on a vibration compaction table for 1 min;
after the compaction is finished, closing and pressing the iron bucket cover, putting the iron bucket cover into a vacuum chamber, heating the vacuum chamber to 200 ℃, simultaneously vacuumizing the vacuum chamber until the internal pressure is not more than 10Kpa, introducing a mixed gas of ammonia and carbon dioxide into the vacuum chamber for replacement for 5min, and keeping the ammonia pipeline unblocked after the replacement is finished;
heating the vacuum chamber to 700 ℃, preserving heat for 8h, continuing to heat to 950 ℃ after heat preservation, and preserving heat for 8 h;
after heat preservation is finished, cooling to room temperature, taking out the iron drum, taking out the valve ball and the valve seat inside, blowing away residual coating powder on the surface of the valve ball and the valve seat by using nitrogen, putting the valve ball and the valve seat into a laser irradiation chamber, performing gas replacement on the inside of the laser irradiation chamber by using nitrogen for 5min, performing laser irradiation on the surface of a stainless steel small shaft by using a 5kw CO2 laser, wherein the spot diameter of a laser beam is 3mm, the scanning speed of the laser beam is 6mm/s, the interval between two adjacent scanning tracks is 1mm, obtaining the valve ball and the valve seat which are covered with metal ceramic coatings after scanning is finished, and grinding the surfaces of the valve ball and the valve seat to enable the surface roughness to reach the mirror surface effect of Ra0.03.
After the treatment, the surface hardness of the ball valve and the ball seat reaches 1750HV0.2, and the service life of the ball valve and the ball seat is improved by 5 times compared with that of a spray welding hard alloy coating.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.
Claims (10)
1. A method for preparing a metal ceramic coating on the surface of austenitic stainless steel is characterized by comprising the following steps:
step one, placing a stainless steel product in an ultrasonic cleaning machine for cleaning for 5-10min, and drying by adopting nitrogen after cleaning;
secondly, placing the dried stainless steel product in a vacuum chamber, embedding the stainless steel product by adopting coating powder, and vibrating for 1-2 min;
step three, after the vibration is finished, heating the vacuum chamber to 200 ℃, vacuumizing and introducing reaction gas for replacement;
step four, heating the vacuum chamber to 800 ℃ at 600-;
step five, heating the vacuum chamber to 900-;
and step six, after the heat preservation is finished, cooling to room temperature, taking out the stainless steel product, putting the stainless steel product into a laser irradiation chamber, replacing gas in the laser irradiation chamber by using protective gas, and irradiating the surface of the stainless steel product by using laser beams.
2. The method for preparing the cermet coating on the austenitic stainless steel surface according to claim 1, wherein, in the second step, the coating powder comprises the following components in mass ratio for carbon nitride: supplying a chromium agent: penetration enhancer: filler (10-22): (40-60): (1-5): (30-45).
3. The method of claim 2, wherein the carbon-nitrogen donor is a solid organic powder.
4. The method for preparing the metal ceramic coating on the austenitic stainless steel surface according to claim 3, wherein the solid organic substance is one or a mixture of polyvinyl chloride, polytetrafluoroethylene and melamine.
5. The method for preparing the metal ceramic coating on the austenitic stainless steel surface according to claim 2, wherein the chromium supplying agent is one or a mixture of metal chromium powder, chromium iron powder and chromium sesquioxide.
6. The method of forming a cermet coating on the surface of austenitic stainless steel according to claim 2, wherein the penetration enhancer is a halogen ammonium salt.
7. The method for preparing a cermet coating on the surface of austenitic stainless steel according to claim 6, wherein the penetration enhancer is one or a mixture of ammonium chloride, ammonium fluoride and ammonium iodide.
8. The method for preparing a cermet coating on the surface of austenitic stainless steel according to claim 2, wherein the filler is one or a mixture of calcined alumina, bauxite and kaolin.
9. The method for preparing the cermet coating on the austenitic stainless steel surface according to claim 1, wherein the reaction gas comprises ammonia gas and a mixture of one or more of nitrogen, hydrogen, carbon monoxide and carbon dioxide in step three.
10. The method for preparing a cermet coating on the surface of austenitic stainless steel according to claim 1, wherein in the sixth step, the irradiation power of the laser beam is 2-10kW, the scanning speed of the laser beam is 5-8mm/s, and the spot diameter of the laser beam is 2-5 mm.
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2019
- 2019-12-17 CN CN201911301039.6A patent/CN111118443A/en active Pending
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| US20050274215A1 (en) * | 2004-06-15 | 2005-12-15 | Geoff Bishop | Worm gear assembly having improved physical properties and method of making same |
| CN102424944A (en) * | 2011-12-08 | 2012-04-25 | 九江学院 | Method for remelting ternary boride metal ceramic gradient coating by using laser |
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| CN107201496A (en) * | 2017-06-12 | 2017-09-26 | 武汉铭高新材料有限公司 | A kind of method for preparing chromium based ceramic metal hardened layer in stainless steel surfaces |
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Application publication date: 20200508 |