CN113249680A - Surface treatment method of high-strength corrosion-resistant precision piston rod - Google Patents
Surface treatment method of high-strength corrosion-resistant precision piston rod Download PDFInfo
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- CN113249680A CN113249680A CN202110524039.3A CN202110524039A CN113249680A CN 113249680 A CN113249680 A CN 113249680A CN 202110524039 A CN202110524039 A CN 202110524039A CN 113249680 A CN113249680 A CN 113249680A
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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
- C23C12/02—Diffusion in one step
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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
- C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C8/60—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using solids, e.g. powders, pastes
- C23C8/72—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using solids, e.g. powders, pastes more than one element being applied in one step
- C23C8/74—Carbo-nitriding
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Abstract
The invention relates to the technical field of piston rod surface treatment, in particular to a surface treatment method of a high-strength corrosion-resistant precision piston rod, which comprises the following steps: ultrasonically cleaning a piston rod, preserving heat at the temperature of 800-; and raising the temperature of the piston rod after nitridation to 1050-. The method provided by the invention is beneficial to obviously refining crystal grains, improving the strength and surface hardness uniformity of the piston rod, and keeping high precision for a long time, and the piston rod can obtain excellent salt spray corrosion resistance and wear resistance due to the addition of other transition metal oxides.
Description
Technical Field
The invention relates to the technical field of piston rod surface treatment, in particular to a surface treatment method of a high-strength corrosion-resistant precision piston rod.
Background
The piston rod is a connecting piece which is applied to motion execution components such as an oil cylinder, an air cylinder and the like and supports a piston to do work, and high technical requirements are needed due to frequent and frequent movement and collision, so the service life and the reliability of the whole product such as the piston, the piston rod and the like are directly influenced by the processing quality of the piston rod, and the processing technology is restricted by the following basic requirements in the processing of the piston rod: 1) sufficient strength, rigidity and stability, 2) excellent wear resistance to obtain better machining over-precision and surface roughness, 3) small difference in surface hardness to facilitate maintaining high precision during application, and 4) excellent resistance to fume corrosion.
The invention discloses a low-temperature salt bath carbonitriding agent and application thereof in surface treatment of a piston rod, and the carbonitriding agent disclosed by the invention has the advantages of low treatment temperature of 450-500 ℃, short time of 40-60min, shallow loose layer with the thickness of the loose layer being less than or equal to 5 mu m, and capability of greatly improving the hardness of a workpiece, and can be used for surface treatment of the piston rod. However, the low-temperature salt bath carbonitriding agent provided by the invention can perform nitriding treatment on the piston rod at low temperature, but the surface hardness (HV0.1/15) of the low-temperature salt bath carbonitriding agent is not higher than 587, and the salt spray test does not exceed 200 h. In addition, the chinese invention patent of prior art publication No. CN106191847A discloses a passivation oxidant for piston rods and its application in preparing silver gray piston rods, which can be applied in preparing silver gray piston rods, and the obtained piston rods have silver gray surfaces, high hardness, strong corrosion resistance and wear resistance, low rejection rate and long service life, and the passivation oxidant for piston rods comprises the following components in percentage by weight: potassium nitrate: 38-40%, potassium dichromate: 26-28%, sodium metavanadate: 20-22%, potassium chloride: 8-10%, sodium nitrite: 2 percent. After the piston rod is subjected to nitridation-passivation oxidation according to the method of the invention, the surface hardness (HV0.1/15) is only up to 570, and the neutral salt spray test is only up to 144 h.
In combination with the above background art, there is a need to develop a processing method that is conducive to significantly improving the strength of the piston rod, and is wear-resistant, corrosion-resistant, and capable of maintaining high precision.
Disclosure of Invention
In order to solve at least one of the technical problems mentioned in the background art, the present invention aims to provide a surface treatment method for a high-strength corrosion-resistant precision piston rod, which is helpful for significantly refining crystal grains, improving the uniformity of the strength and surface hardness of the piston rod, and facilitating the long-term maintenance of high precision, and the addition of other transition metal oxides can enable the piston rod to obtain exceptional salt spray corrosion resistance and wear resistance.
In order to achieve the above object, the present invention provides the following technical solutions.
The application of the iron-doped graphene in the surface treatment of the piston rod comprises the step of carrying out nitridation treatment on the piston rod by using a carbonitriding agent containing the iron-doped graphene.
The application is to improve the grain size grade of the piston rod.
The application consists in increasing the strength of the piston rod.
The application consists in reducing the surface hardness difference.
The iron-doped graphene is prepared by doping graphene with iron element not less than 50% of the weight of graphene.
The preparation method of the iron-doped graphene specifically comprises the following steps:
adding urea into graphene oxide dispersion liquid with the concentration not higher than 1mg/mL, fully stirring, mixing with iron chloride aqueous solution, adding hydrogen peroxide at room temperature, continuously stirring for not less than 12h, centrifuging to remove supernatant, adding 2-5 times of distilled water, transferring into a high-pressure hydrothermal reaction kettle, reacting at 170-200 ℃ for at least 12h, centrifuging to remove supernatant, drying, calcining at 820-850 ℃ for not less than 3h by introducing nitrogen, and grinding to 200-mesh sieve.
The addition amount of the hydrogen peroxide is 0.1-1% of the volume of the graphene oxide dispersion liquid.
The iron element in an atomic state or a nanocluster form can be attached to the graphene sheet layer and the surface of the graphene sheet layer by doping and modifying sufficient ferric chloride, the iron element can be introduced when the carbon and nitrogen co-permeation is carried out on the piston rod by taking the graphene as a raw material, the nitrogen doping of urea and the graphene can help the carbon, the nitride or the nitrocarbon compound to be formed with other elements when the carbon and the nitrogen are co-permeated, mass points of the carbon, the nitride or the nitrocarbon compound are limited at a grain boundary, the growth of austenite grains in the reheating process can be prevented, the recrystallization growth of the austenite grains can be prevented in the recrystallization process, the grains can be refined, the strength and the surface hardness uniformity degree of the piston rod can be further remarkably improved, the surface hardness difference value is reduced, the surface hardness uniformity of the piston rod is high, and the high precision degree can be kept after the piston rod is used for a long time.
The carbonitriding agent for treating the surface of the piston rod comprises the iron-doped graphene.
The carbonitriding agent for the surface treatment of the piston rod comprises the following components in percentage by weight:
wherein the other transition metal oxides are oxides of titanium, cobalt and niobium, and
Mtitanium (IV):(MCobalt+MNiobium (Nb)) 45-55:1, more preferably 48-55:1, most preferably 50: 1.
MCobalt:MNiobium (Nb)12-16:1, more preferably 14-15:1, most preferably 14: 1.
In the scheme of the invention, on the basis of the components of the traditional carbonitriding agent, such as chromium oxide, molybdenum oxide, vanadium oxide, nickel oxide, borax and the like, other transition metal oxides, such as oxides of titanium, cobalt and niobium, are added, after the carbonitriding agent is subjected to nitriding treatment by the carbonitriding agent, the components of the carbonitriding agent are melted, a carburized layer is formed on the surface of the piston rod, fine carbides and/or nitrides of elements, such as vanadium, titanium, cobalt, niobium and the like, are included in the carburized layer, mass points are limited at a grain boundary, grain growth is prevented, grains are refined, after the molar ratio of the other transition metal oxides is further defined, the piston rod can unexpectedly obtain the extremely excellent salt spray corrosion resistance and wear resistance, the possible reasons are that a certain mutual restriction relationship exists among titanium, cobalt and niobium, the carburized layer grains are fine, salt spray is not easy to infiltrate, and a corrosion channel cannot be rapidly formed, therefore, the salt spray corrosion resistance is excellent, and in addition, the molar definition of the other transition metal oxides has an important influence on the strength and the wear resistance of the piston rod after treatment.
The application of the carbonitriding agent in surface treatment of the piston rod.
A piston rod surface treatment method comprising:
a cleaning step of rinsing and drying the processed piston rod with deionized water after ultrasonic cleaning;
a preheating step of preserving the heat of the cleaned piston rod at the temperature of 800-;
a nitriding step of placing the preheated piston rod in a carbonitriding agent, raising the temperature to 900-;
a quenching step of raising the temperature of the piston rod after nitridation to 1050-;
a cooling step of soaking the quenched piston rod in cooling liquid;
and (3) tempering, namely naturally cooling the cooled piston rod after heat preservation for at least 2 hours at the temperature of not less than 300 ℃.
The preheating step is accomplished in an inert atmosphere.
The nitriding step is completed under continuous ammonia gas introduction.
In the method, firstly, impurities such as oil stains and the like on the surface of the piston rod are cleaned under ultrasonic, then the piston rod is preheated in inert gas to avoid oxidation, then the piston rod is nitrided by a carbonitriding agent under the condition of continuously introducing ammonia gas, the ammonia gas is heated to generate active nitrogen atoms to participate in the synthesis of nitrides of metal elements in a carburized layer, carbon elements in iron-doped graphene, urea and charcoal in the carburized agent also partially participate in the synthesis of carbides of the metal elements, thereby forming a plurality of fine carbon nitrides in the infiltrated layer, preventing the growth of crystal grains, refining the crystal grains, further limiting the molar ratio of other transition metal oxides, the piston rod obtains excellent salt spray corrosion resistance and wear resistance, the grain size can be stably controlled to be 6 or above, the piston rod has excellent strength and surface hardness uniformity, and high precision can be maintained after long-term use.
The above-described preferred conditions may be combined with each other to obtain a specific embodiment, in accordance with common knowledge in the art.
The raw materials or reagents involved in the invention are all common commercial products, and the operations involved are all routine operations in the field unless otherwise specified.
The invention has the beneficial effects that:
iron element can be introduced when the piston rod is subjected to carbonitriding by taking iron-doped graphene as a raw material, the nitrogen doping of urea and the graphene are beneficial to forming carbide and/or nitride with other elements during the nitrocarburizing, mass points are limited at a grain boundary, the growth of austenite grains in the reheating process is prevented, the recrystallization of the austenite grains can be prevented in the recrystallization process, the grains are refined, the strength and the surface hardness uniformity of the piston rod are further remarkably improved, the surface hardness difference is reduced, the surface hardness uniformity of the piston rod is high, and the high precision can be kept after the piston rod is used for a long time; during nitriding treatment, the components of the carbonitriding agent are melted, a carburized layer is formed on the surface of the piston rod, fine carbides and/or nitrides of elements such as vanadium, titanium, cobalt and niobium are included in the carburized layer, crystal grain growth is prevented, crystal grains are refined, and after the molar ratio of other transition metal oxides is further defined, the piston rod can unexpectedly obtain excellent salt spray corrosion resistance and wear resistance, probably because certain mutual restriction relationship exists among titanium, cobalt and niobium, the carburized layer has fine crystal grains, salt spray is not easy to infiltrate, a corrosion channel cannot be rapidly formed, and therefore the salt spray corrosion resistance is excellent.
The invention adopts the technical scheme for achieving the purpose, makes up the defects of the prior art, and has reasonable design and convenient operation.
Drawings
The foregoing and/or other objects, features, advantages and embodiments of the invention will be more readily understood from the following description taken in conjunction with the accompanying drawings in which:
fig. 1 is a schematic X-ray diffraction diagram of iron-doped graphene obtained in example 1;
FIG. 2 is a graph showing the mean hardness and the difference in surface hardness;
FIG. 3 is a schematic illustration of a grain size grade of a infiltrated layer;
FIG. 4 is a graphical representation of the results for neutral salt spray corrosion resistance.
Detailed Description
The invention provides application of iron-doped graphene in surface treatment of a piston rod, which comprises the step of carrying out nitridation treatment on the piston rod by using a carbonitriding agent containing the iron-doped graphene.
The application consists in increasing the grain size grade of the piston rod and/or increasing the strength of the piston rod and/or reducing the surface hardness difference.
The iron-doped graphene is prepared by doping graphene with iron element not less than 50% of the weight of graphene.
The preparation method of the iron-doped graphene specifically comprises the following steps:
adding urea into graphene oxide dispersion liquid with the concentration not higher than 1mg/mL, fully stirring, mixing with iron chloride aqueous solution, adding hydrogen peroxide at room temperature, continuously stirring for not less than 12h, centrifuging to remove supernatant, adding 2-5 times of distilled water, transferring into a high-pressure hydrothermal reaction kettle, reacting at 170-200 ℃ for at least 12h, centrifuging to remove supernatant, drying, calcining at 820-850 ℃ for not less than 3h by introducing nitrogen, and grinding to 200-mesh sieve.
The addition amount of the urea is 1-10 times of the weight of the graphene oxide.
The addition amount of the iron element is not less than 50% by weight of the graphene, more preferably 60-100%, and most preferably 75%.
The addition amount of the hydrogen peroxide is 0.1-1% of the volume of the graphene oxide dispersion liquid.
The rotation speed of the stirring is 120-600 r/min.
The rotating speed of the centrifugation is 1200-3000r/min, and the centrifugation is at least 30 min.
The nitrogen gas was introduced at a flow rate of 100 and 500 mL/min.
The invention also provides a carbonitriding agent for surface treatment of the piston rod, which comprises the iron-doped graphene.
The carbonitriding agent for surface treatment of the piston rod comprises the following components in percentage by weight:
wherein the other transition metal oxides are oxides of titanium, cobalt and niobium, and
Mtitanium (IV):(MCobalt+MNiobium (Nb)) 45-55:1, more preferably 48-55:1, most preferably 50: 1.
MCobalt:MNiobium (Nb)12-16:1, more preferably 14-15:1, most preferably 14: 1.
MTitanium (IV)、MCobalt、MNiobium (Nb)The molar amounts of the oxides of titanium, cobalt and niobium, respectively.
The oxide of titanium being TiO2(relative molecular mass: 80), the oxide of cobalt is CoO (relative molecular mass: 75), and the oxide of niobium is NbO2(relative molecular mass is 125).
The invention also provides application of the carbonitriding agent in surface treatment of the piston rod.
The invention provides a piston rod surface treatment method, which comprises the following steps:
a cleaning step of rinsing and drying the processed piston rod with deionized water after ultrasonic cleaning;
a preheating step of preserving the heat of the cleaned piston rod at the temperature of 800-;
a nitriding step of placing the preheated piston rod in a carbonitriding agent, raising the temperature to 900-;
a quenching step of raising the temperature of the piston rod after nitridation to 1050-;
a cooling step of soaking the quenched piston rod in cooling liquid;
and (3) tempering, namely naturally cooling the cooled piston rod after heat preservation for at least 2 hours at the temperature of not less than 300 ℃.
The ultrasonic frequency of ultrasonic cleaning is not lower than 80HKz, and the power density is not lower than 0.5W/cm2And the ultrasonic cleaning time is not less than 30 min.
The preheating step is accomplished in an inert atmosphere.
The nitriding step is completed under continuous ammonia gas introduction.
The cooling liquid comprises the following components: 80-90% of water, 5-10% of sodium chloride, 1-3% of malic acid, 1-3% of sodium alkyl benzene sulfonate, 1-3% of polyethylene glycol and 0.5-1% of defoaming agent.
The piston rod used in the embodiment of the application is made of 40CrNiMoA alloy steel.
The present invention is described in detail below.
Example 1: an iron-doped graphene:
this example provides an iron-doped graphene, preparing 200mL of graphene oxide dispersion with a concentration of 0.5mg/mL, adding 0.3g of urea into the dispersion, fully stirring at 300r/min for 15min, dissolving 0.362g of ferric chloride hexahydrate into 100mL of distilled water, adding the dispersion, adding 1mL of hydrogen peroxide at room temperature, continuously stirring for 12h, centrifuging at 1800r/min for 30min to remove supernatant, adding 4 times of distilled water, transferring into a high-pressure hydrothermal reaction kettle, reacting at 180 ℃ for 12h, centrifuging at 1800r/min for 30min to remove supernatant, drying, placing at 845 ℃ and calcining at 400mL of nitrogen for 4h, and grinding until 200 mesh is passed, wherein an X-ray diffraction pattern is shown in fig. 1, and X-ray diffraction patterns of 30.0 °, 35.4 °, 43.0 °, 57.0 ° and 62.6 ° correspond to ferroferric oxide diffraction peak positions, and X-ray diffraction peaks of 44.7 °, 65.0 ° and 82.4 ° correspond to iron atomic diffraction peak positions, the iron element is doped into the graphene in two forms of ferroferric oxide and iron atoms.
Example 2: another iron-doped graphene:
in this embodiment, another iron-doped graphene is provided, and the specific method is substantially the same as that in embodiment 1, except that malic acid is used instead of urea in this embodiment.
Example 3: a doped graphene:
this example provides a doped graphene, which is prepared by the same method as example 1, except that ferric chloride hexahydrate is not added, and only 100mL of distilled water is added to the graphene dispersion to prepare the doped graphene.
Example 4: another iron-doped graphene:
this example provides another iron-doped graphene, which is substantially the same as example 1, except that in this example, 0.121g of ferric chloride hexahydrate is dissolved in 100mL of distilled water and the graphene dispersion is added to prepare the iron-doped graphene.
Example 5: another iron-doped graphene:
this example provides another iron-doped graphene, and the specific method is substantially the same as example 1, except that in this example, 0.241g of ferric chloride hexahydrate is dissolved in 100mL of distilled water and added to the graphene dispersion to prepare the iron-doped graphene.
Example 6: another iron-doped graphene:
this example provides another iron-doped graphene, which is substantially the same as example 1, except that 0.482g of ferric chloride hexahydrate is dissolved in 100mL of distilled water and the graphene dispersion is added to prepare the iron-doped graphene.
Example 7: a surface treatment method of a piston rod comprises the following steps:
the embodiment provides a piston rod surface treatment method, which comprises the following specific steps:
1) cleaning: soaking the processed piston rod in deionized water at an ultrasonic frequency of 80HKz and a power density of 0.6W/cm2Ultrasonic cleaning for 45min, rinsing with deionized water and drying;
2) preheating: keeping the cleaned piston rod at 850 ℃ for 2h in a nitrogen atmosphere, and then cooling to 480 ℃;
3) nitriding: preparing a carbonitriding agent: 20% of the iron-doped graphene obtained in example 1, 12% of urea, 10% of chromium oxide, 1.2% of molybdenum oxide, 1.2% of vanadium oxide, 0.6% of nickel oxide, 10% of borax, 4.905% of titanium oxide, 0.085% of cobalt oxide, 0.01% of niobium oxide and the balance of charcoal, wherein the total amount is 100%; placing the preheated piston rod in a carbonitriding agent, continuously introducing sufficient ammonia gas, heating to 950 ℃, and carrying out heat preservation and nitridation for 6 hours;
4) quenching: heating the piston rod subjected to nitridation to 1050 ℃ and preserving heat for 4 hours;
5) and (3) cooling: the piston rod after quenching is placed in cooling liquid for soaking, and the cooling liquid comprises the following components: 82.5% of water, 10% of sodium chloride, 2% of malic acid, 3% of sodium alkyl benzene sulfonate, 2% of polyethylene glycol and 0.5% of defoaming agent;
6) tempering: and (4) preserving the heat of the cooled piston rod at 350 ℃ for 3h, and then naturally cooling.
Example 8: a surface treatment method of a piston rod comprises the following steps:
the embodiment provides a piston rod surface treatment method, which comprises the following specific steps:
1) cleaning: soaking the processed piston rod in deionized water at an ultrasonic frequency of 100HKz and a power density of 0.8W/cm2Ultrasonic cleaning for 30min, rinsing with deionized water and drying;
2) preheating: keeping the cleaned piston rod at 900 ℃ for 2h in a nitrogen atmosphere, and then cooling to 520 ℃;
3) nitriding: preparing a carbonitriding agent: 14% of the iron-doped graphene obtained in example 1, 10% of urea, 8% of chromium oxide, 1.2% of molybdenum oxide, 1.5% of vanadium oxide, 0.5% of nickel oxide, 10% of borax, 7.846% of titanium oxide, 0.137% of cobalt oxide, 0.016% of niobium oxide and the balance of charcoal, wherein the total amount is 100%; placing the preheated piston rod in a carbonitriding agent, continuously introducing sufficient ammonia gas, heating to 900 ℃, and carrying out heat preservation and nitridation for 9 hours;
4) quenching: heating the piston rod subjected to nitridation to 1050 ℃ and preserving heat for 4 hours;
5) and (3) cooling: the piston rod after quenching is placed in cooling liquid for soaking, and the cooling liquid comprises the following components: 84.5% of water, 10% of sodium chloride, 2% of malic acid, 1% of sodium alkyl benzene sulfonate, 20002% of polyethylene glycol and 0.5% of defoaming agent;
6) tempering: and (4) preserving the heat of the cooled piston rod at the temperature of 300 ℃ for 4h, and then naturally cooling.
Example 9: a surface treatment method of a piston rod comprises the following steps:
the embodiment provides a piston rod surface treatment method, which comprises the following specific steps:
1) cleaning: soaking the processed piston rod in deionized water at an ultrasonic frequency of 90HKz and a power density of 0.8W/cm2Ultrasonic cleaning for 40min, rinsing with deionized water and drying;
2) preheating: keeping the cleaned piston rod at 900 ℃ for 3h in a nitrogen atmosphere, and then cooling to 500 ℃;
3) nitriding: preparing a carbonitriding agent: 16% of iron-doped graphene obtained in example 1, 13.5% of urea, 12% of chromium oxide, 1.4% of molybdenum oxide, 1.4% of vanadium oxide, 0.8% of nickel oxide, 10% of borax, 9.808% of titanium oxide, 0.172% of cobalt oxide, 0.02% of niobium oxide, and the balance of charcoal, wherein the total is 100%; placing the preheated piston rod in a carbonitriding agent, continuously introducing sufficient ammonia gas, heating to 980 ℃, and carrying out heat preservation and nitridation for 8 hours;
4) quenching: heating the piston rod subjected to nitridation to 1080 ℃ and preserving heat for 4 hours;
5) and (3) cooling: the piston rod after quenching is placed in cooling liquid for soaking, and the cooling liquid comprises the following components: 85% of water, 7.5% of sodium chloride, 2% of malic acid, 3% of sodium alkyl benzene sulfonate, 2% of polyethylene glycol and 0.5% of defoaming agent;
6) tempering: and (4) preserving the heat of the cooled piston rod at the temperature of 400 ℃ for 2h, and then naturally cooling.
Example 10: a surface treatment method of a piston rod comprises the following steps:
the present embodiment provides a method for treating a surface of a piston rod, which includes the steps substantially the same as those in embodiment 9, except that the iron-doped graphene in this embodiment is obtained from embodiment 2.
Example 11: a surface treatment method of a piston rod comprises the following steps:
the present embodiment provides a method for treating a surface of a piston rod, which includes steps substantially the same as those in embodiment 9, except that the doped graphene in this embodiment is obtained from embodiment 3.
Example 12: a surface treatment method of a piston rod comprises the following steps:
the present embodiment provides a method for treating a surface of a piston rod, which includes the steps substantially the same as those in embodiment 9, except that the iron-doped graphene in this embodiment is obtained from embodiment 4.
Example 13: a surface treatment method of a piston rod comprises the following steps:
this example provides a method for treating a surface of a piston rod, which includes the steps substantially the same as those in example 9, except that the iron-doped graphene in this example is obtained from example 5.
Example 14: a surface treatment method of a piston rod comprises the following steps:
the present embodiment provides a method for treating a surface of a piston rod, which includes the steps substantially the same as those in embodiment 9, except that the iron-doped graphene in this embodiment is obtained from embodiment 6.
Example 15: a surface treatment method of a piston rod comprises the following steps:
this example provides a method for treating the surface of a piston rod, which comprises the same steps as those of example 9 except that cobalt oxide is not added to the carbonitriding agent of this example and the shortage is supplemented with charcoal.
Example 16: a surface treatment method of a piston rod comprises the following steps:
this example provides a piston rod surface treatment method, which has the same steps as example 9 except that cobalt oxide and niobium oxide are not added to the carbonitriding agent of this example and the deficiency is supplemented with charcoal.
Example 17: a surface treatment method of a piston rod comprises the following steps:
the embodiment provides a piston rod surface treatment method, which comprises the following specific steps:
1) cleaning: soaking the processed piston rod in deionized water at an ultrasonic frequency of 90HKz and a power density of 0.8W/cm2Ultrasonic cleaning for 40min, rinsing with deionized water and drying;
2) preheating: keeping the cleaned piston rod at 900 ℃ for 3h in a nitrogen atmosphere, and then cooling to 500 ℃;
3) nitriding: preparing a carbonitriding agent: 16% of iron-doped graphene obtained in example 1, 13.5% of urea, 12% of chromium oxide, 1.4% of molybdenum oxide, 1.4% of vanadium oxide, 0.8% of nickel oxide, 10% of borax, 9.804% of titanium oxide, 0.165% of cobalt oxide, 0.031% of niobium oxide, and the balance of charcoal, wherein the total is 100%; placing the preheated piston rod in a carbonitriding agent, continuously introducing sufficient ammonia gas, heating to 980 ℃, and carrying out heat preservation and nitridation for 8 hours;
4) quenching: heating the piston rod subjected to nitridation to 1080 ℃ and preserving heat for 4 hours;
5) and (3) cooling: the piston rod after quenching is placed in cooling liquid for soaking, and the cooling liquid comprises the following components: 85% of water, 7.5% of sodium chloride, 2% of malic acid, 3% of sodium alkyl benzene sulfonate, 2% of polyethylene glycol and 0.5% of defoaming agent;
6) tempering: and (4) preserving the heat of the cooled piston rod at the temperature of 400 ℃ for 2h, and then naturally cooling.
Example 18: a surface treatment method of a piston rod comprises the following steps:
the embodiment provides a piston rod surface treatment method, which comprises the following specific steps:
1) cleaning: soaking the processed piston rod in deionized water at an ultrasonic frequency of 90HKz and a power density of 0.8W/cm2Ultrasonic cleaning for 40min, rinsing with deionized water and drying;
2) preheating: keeping the cleaned piston rod at 900 ℃ for 3h in a nitrogen atmosphere, and then cooling to 500 ℃;
3) nitriding: preparing a carbonitriding agent: 16% of iron-doped graphene obtained in example 1, 13.5% of urea, 12% of chromium oxide, 1.4% of molybdenum oxide, 1.4% of vanadium oxide, 0.8% of nickel oxide, 10% of borax, 9.756% of titanium oxide, 0.091% of cobalt oxide, 0.152% of niobium oxide and the balance of charcoal, wherein the total amount is 100%; placing the preheated piston rod in a carbonitriding agent, continuously introducing sufficient ammonia gas, heating to 980 ℃, and carrying out heat preservation and nitridation for 8 hours;
4) quenching: heating the piston rod subjected to nitridation to 1080 ℃ and preserving heat for 4 hours;
5) and (3) cooling: the piston rod after quenching is placed in cooling liquid for soaking, and the cooling liquid comprises the following components: 85% of water, 7.5% of sodium chloride, 2% of malic acid, 3% of sodium alkyl benzene sulfonate, 2% of polyethylene glycol and 0.5% of defoaming agent;
6) tempering: and (4) preserving the heat of the cooled piston rod at the temperature of 400 ℃ for 2h, and then naturally cooling.
Example 19: a surface treatment method of a piston rod comprises the following steps:
the embodiment provides a piston rod surface treatment method, which comprises the following specific steps:
1) cleaning: piston rod of completion of processingSoaking in deionized water at ultrasonic frequency of 90HKz and power density of 0.8W/cm2Ultrasonic cleaning for 40min, rinsing with deionized water and drying;
2) preheating: keeping the cleaned piston rod at 900 ℃ for 3h in a nitrogen atmosphere, and then cooling to 500 ℃;
3) nitriding: preparing a carbonitriding agent: 16% of iron-doped graphene obtained in example 1, 13.5% of urea, 12% of chromium oxide, 1.4% of molybdenum oxide, 1.4% of vanadium oxide, 0.8% of nickel oxide, 10% of borax, 9.108% of titanium oxide, 0.797% of cobalt oxide, 0.095% of niobium oxide and the balance of charcoal, wherein the total is 100%; placing the preheated piston rod in a carbonitriding agent, continuously introducing sufficient ammonia gas, heating to 980 ℃, and carrying out heat preservation and nitridation for 8 hours;
4) quenching: heating the piston rod subjected to nitridation to 1080 ℃ and preserving heat for 4 hours;
5) and (3) cooling: the piston rod after quenching is placed in cooling liquid for soaking, and the cooling liquid comprises the following components: 85% of water, 7.5% of sodium chloride, 2% of malic acid, 3% of sodium alkyl benzene sulfonate, 2% of polyethylene glycol and 0.5% of defoaming agent;
6) tempering: and (4) preserving the heat of the cooled piston rod at the temperature of 400 ℃ for 2h, and then naturally cooling.
Example 20: a surface treatment method of a piston rod comprises the following steps:
the present embodiment provides a piston rod surface treatment method, which includes the steps substantially the same as those in embodiment 9, except that in the cooling step of the present embodiment, the piston rod after quenching is placed in a cooling liquid to be cooled to room temperature, and the cooling liquid includes: the piston rod after quenching is placed in cooling liquid for soaking, and the cooling liquid comprises the following components: 84.5% of water, 7.5% of sodium chloride, 2% of malic acid, 3% of sodium alkyl benzene sulfonate, 2% of polyethylene glycol, 0.5% of lithium carbonate and 0.5% of defoaming agent.
Experimental example 1:
according to the prior art, the appearance and physical measurement of the piston rods treated by different schemes in examples 7-20 are respectively carried out, and the method specifically comprises the following steps: the piston rod was observed for the presence of cracks and gaps at 30 times magnification, and the impact strength of the piston rod was measured in a universal testing machine, and the statistical results are shown in table 1.
TABLE 1 measurement results of appearance, Strength and Friction coefficient
As can be seen from Table 1, no cracks or gaps are found on the surface of the piston rod treated by the embodiments 7-20, which indicates that the carbonitriding agent can be tightly combined with the piston rod body, and the density of the infiltrated layer is high, which is beneficial to improving the mechanical property of the piston, and as can be seen from table 1, the examples 7-9 and examples 13 and 14 of the preferred embodiment have excellent impact strength which is improved by 190-209% compared with that before treatment, the strength is obviously improved, as can be seen from comparative examples 9 to 14, the doping of iron in graphene is beneficial to improving the strength of the material, the possible reasons are that the piston rod body contains iron elements, so the carburized layer is easy to adhere to the surface of the piston rod, and the iron elements are added to form compounds such as iron nitride and/or iron carbide and/or iron oxide and further strengthen the carburized layer; from examples 15 to 19, it is understood that the addition of titanium oxide, cobalt oxide, and niobium oxide is advantageous for improving the strength of the piston rod, and the addition amount thereof has a certain influence on the strength of the strength improvement; as can be seen from comparative examples 9 and 20, the addition of a small amount of lithium carbonate to the coolant helps to improve the impact strength of the piston rod, and the possible reason is that the lithium carbonate on the surface of the piston rod is decomposed slightly, so that lithium oxide is precipitated, and a micro oxide film formed on the surface of the piston rod is damaged, which is beneficial to improving the cooling capacity of the coolant, thereby improving the impact strength of the piston rod to a certain extent.
Experimental example 2:
the rockwell hardness test was performed on each of the piston rods treated in the embodiments 7 to 20, and the measurements were performed at randomly selected 5 positions at the end and the center of the piston rod, and the average hardness and the difference surface hardness (maximum hardness-minimum hardness) were counted, and the statistical results are shown in fig. 2. As can be seen from fig. 2, the iron doped in the graphene is beneficial to improving the hardness of the piston rod and reducing the surface hardness difference, i.e., improving the uniformity of the infiltrated layer, in the preferred embodiment examples 7 to 9, the surface hardness difference of the piston rod can be reduced to 0.5 or less, the infiltrated layer has high uniformity and high hardness, and higher precision can be maintained in the long-term use process; it can also be seen that more iron doping is not better, more iron doping also increases the hardness difference, possibly because excessive iron doping can cause agglomeration and affect the uniform distribution of the infiltrated layer; it is also known that the addition of other transition metal oxides is beneficial to the increase of hardness, but has a limited effect.
Experimental example 3:
the grain size grade of the carburized layer of each piston rod interface in examples 7-20 is measured according to ASTM E112, and the statistical result is shown in FIG. 3, which shows that the grain size grade of the carburized layer of the piston rod surface treated by the schemes in examples 7-9 and 13-14 is not lower than 6, the carburized layer crystal grains are better refined, and the maintenance of the anti-corrosion performance is facilitated; comparative examples 10 to 14 show that the doping of iron has a significant influence on the improvement of the grain size grade, and the doping of a proper amount of iron is beneficial to refining grains; it is understood from comparative examples 15 to 20 that the addition of cobalt oxide and niobium oxide to the carbonitriding agent has an accelerating effect on grain refinement.
Experimental example 4:
the corrosion resistance of the piston rods treated in examples 7-20 was tested in a neutral salt spray test at ph6.5-7.2, respectively, and the time for rust to appear on the surfaces was examined, and the statistical results are shown in fig. 4. As can be seen from the graph of FIG. 4, the piston rods treated by the solutions of examples 7-9, 13 and 14 have excellent salt spray corrosion resistance, which is not lower than 210 h; meanwhile, the salt spray corrosion resistance of the seepage layer lifting piston rod is not obvious due to doping modification of graphene; the corrosion resistance is obviously affected by adding proper amounts of titanium oxide, cobalt oxide and niobium oxide in the carbonitriding agent, specifically, the neutral salt spray corrosion resistance time can be reduced to be less than 100h when no cobalt oxide and/or niobium oxide is added, while in example 17 (the molar ratio of cobalt to niobium is about 9:1) and example 18 (the molar ratio of cobalt to niobium is about 1:1), excessive addition of expensive metal niobium oxide is unfavorable for improving the corrosion resistance, and in example 19 (the molar sum of cobalt to niobium is about 10% of the molar amount of titanium), the same ratio of cobalt oxide and niobium oxide content is obviously unfavorable for improving the salt spray corrosion resistance.
Conventional techniques in the above embodiments are known to those skilled in the art, and therefore, will not be described in detail herein.
The invention is not the best known technology.
Claims (8)
1. The application of the iron-doped graphene in the surface treatment of the piston rod is characterized in that:
the application comprises nitriding the piston rod with a carbonitriding agent containing iron-doped graphene.
2. Use according to claim 1, characterized in that: the application lies in
The grain size grade of the piston rod is improved; and/or
The strength of the piston rod is improved; and/or
The difference in surface hardness is reduced.
3. Use according to claim 1 or 2, characterized in that: the iron-doped graphene is prepared by doping graphene with iron element not less than 50% of the weight of graphene.
4. Use according to claim 1 or 2, characterized in that: the preparation method of the iron-doped graphene specifically comprises the following steps: adding urea into graphene oxide dispersion liquid with the concentration not higher than 1mg/mL, fully stirring, mixing with iron chloride aqueous solution, adding hydrogen peroxide at room temperature, continuously stirring for not less than 12h, centrifuging to remove supernatant, adding 2-5 times of distilled water, transferring into a high-pressure hydrothermal reaction kettle, reacting at 170-200 ℃ for at least 12h, centrifuging to remove supernatant, drying, calcining at 820-850 ℃ for not less than 3h by introducing nitrogen, and grinding to 200-mesh sieve.
5. The carbonitriding agent for the surface treatment of the piston rod is characterized in that: including the aforementioned iron-doped graphene.
6. The carbonitriding agent according to claim 5, characterized by further comprising other transition metal oxides, the other transition metal oxides being oxides of titanium, cobalt and niobium, and
Mtitanium (IV):(MCobalt+MNiobium (Nb))＝45-55:1；
MCobalt:MNiobium (Nb)＝12-16:1。
7. Use of a carbonitriding agent according to claim 5 or 6 for the surface treatment of a piston rod.
8. The piston rod surface treatment method is characterized by comprising the following steps:
a cleaning step of rinsing and drying the processed piston rod with deionized water after ultrasonic cleaning;
a preheating step of preserving the heat of the cleaned piston rod at the temperature of 800-;
a nitridation step of placing the preheated piston rod in the carbonitriding agent in the claim 5 or 6, raising the temperature to 900-1050 ℃, and preserving the temperature for at least 6 h;
a quenching step of raising the temperature of the piston rod after nitridation to 1050-;
a cooling step of soaking the quenched piston rod in cooling liquid;
and (3) tempering, namely naturally cooling the cooled piston rod after heat preservation for at least 2 hours at the temperature of not less than 300 ℃.
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