CN101736283A - Composite processing device and processing method for nitriding and oxidizing surface of low-alloy steel - Google Patents

Abstract

The invention discloses a low-alloy steel surface nitriding and oxidation composite treatment device and a treatment method. The device includes a vacuum furnace, an air intake system, a vacuum system, a power supply system, and a temperature measurement system. The vacuum furnace is installed There is a hollow cathode auxiliary device and a workpiece platform. The hollow cathode auxiliary device is composed of two small cylinders and a large cylinder with holes in different diameters. The small cylinder and the large cylinder are respectively connected to the cathode of the power supply. The small cylinder is placed with an insulating ceramic sheet; the workpiece platform includes a support and a stage, the support is located on the base of the vacuum furnace, and the stage is located on the support for placing The workpiece is connected to the anode of the power supply. In the present invention, through the placement of the hollow cathode device, the discharge intensity and ionization rate are improved by using the hollow cathode discharge, thereby producing high-concentration, high-activity permeating substances, and forming a material with good corrosion resistance, high hardness, and good friction and wear performance on the surface. modified layer.

Description

A kind of low-alloy steel surface nitriding oxidation composite treatment device and treatment method

technical field

The invention relates to a surface nitriding and oxidation composite treatment technology, in particular to a low alloy steel surface nitriding and oxidation composite treatment device and treatment method.

Background technique

Low-alloy steel is widely used in the manufacture of various mechanical parts of automobiles, tractors, ships, steam turbines, and heavy-duty machine tools. In order to meet its service conditions and prolong its service life, it is necessary to heat-treat the surface to improve its surface strength, wear resistance, and corrosion resistance. properties and fatigue resistance, etc. Ion nitriding is widely used as one of the heat treatments. Parts after ion nitriding have high surface hardness, good wear resistance, and greatly improved corrosion resistance and fatigue strength. However, in the process of ion nitriding, there is a problem of looseness in the compound layer, and some holes of different sizes and shapes are formed on the surface of the part, which has a certain impact on wear resistance and corrosion resistance.

In order to overcome the above problems, nitriding and oxidation composite treatment, as a process that can meet the requirements of wear resistance and corrosion resistance at the same time, has been widely studied and applied. The common point of these nitriding and oxidation composite treatment technologies is that the workpiece is used as the cathode, which has two major disadvantages:

1. In the process of ion nitriding, ions bombard the surface of the workpiece, and there are problems such as uneven temperature, surface arcing and edge effects;

2. The effect of ion oxidation on the surface after nitriding is not good, and a long oxidation time is required.

Contents of the invention

In order to solve the above-mentioned problems existing in the prior art, the purpose of the present invention is to propose a low-alloy steel surface nitriding and oxidation composite treatment device and treatment method to enhance the nitriding and oxidation effect, avoid arcing and edge effects, and shorten the ion oxidation process. time.

In order to achieve the above object, the technical scheme of the present invention is as follows: a low-alloy steel surface nitriding and oxidation composite treatment device includes a vacuum furnace, an air intake system, a vacuum system, a power supply system, and a temperature measurement system. The infiltration equipment is composed of a vacuum furnace body and a furnace door; the air intake system includes ammonia cylinders, oxygen cylinders, argon cylinders, flow controllers and air inlets, and the air inlets are installed on the side of the vacuum furnace; The power supply system adopts a pulse-charged DC high-voltage power supply or a DC sputtering high-voltage power supply; the temperature measurement system is a commonly used S-type thermocouple installed at a position 2 to 4 cm away from the stage; the vacuum pumping system includes a vacuum pump and Its pipeline, the vacuum pump is connected to the base of the vacuum furnace through the pipeline; a hollow cathode auxiliary device and a workpiece platform are installed in the vacuum furnace, and the hollow cathode auxiliary device is composed of two holes with different diameters The small cylinder and the large cylinder are composed of a coaxial double-layer cylinder, which are located on the insulating ring and separated by the insulating ring. The small cylinder and the large cylinder are respectively connected to the power supply Cathode connection, the small cylinder is placed with an insulating ceramic sheet; the workpiece platform includes a support and a stage, and the support is located on the base of the vacuum furnace; the stage is made of stainless steel , located on the support, used to place workpieces, the said stage and the furnace wall of the vacuum furnace are respectively connected to the anode of the power supply.

The support according to the invention is made of conductive material or insulating material.

The small cylinder and the large cylinder of the present invention are made of low-carbon steel, the diameter of the small cylinder is 350-400mm, the diameter of the large cylinder is 364-418mm, and the holes with a diameter of 11-12mm are evenly distributed on the small cylinder , the distance between the holes is 12-15mm; the distance between the large cylinder and the small cylinder is kept at 7-9mm; the thickness of the insulating ceramic sheet is 7-10mm, and its diameter is slightly larger than that of the small cylinder.

A kind of low alloy steel surface nitriding oxidation compound treatment method comprises the following steps:

A. Cleaning and loading of the workpiece

Clean the surface of the workpiece with industrial cleaning agent, then load the furnace, and place the workpiece on the stage;

B. Vacuumizing and glowing

Start the vacuum pump to pump air. When the vacuum degree in the vacuum furnace reaches 10-20 Pa, open the ammonia gas bottle, fill the purified ammonia gas through the air inlet, and adjust the flow rate of the ammonia gas to keep the pressure in the vacuum furnace at 133-20 Pa. 1333Pa, turn on the power, so that the ammonia in the vacuum furnace is ionized under the action of a high-voltage electric field, resulting in a glow discharge effect;

C. Nitriding treatment

Adjust the distance between the small cylinder and the large cylinder. After the small cylinder and the large cylinder are connected to the cathode power supply, adjust the air pressure in the vacuum furnace to generate a glow discharge. The electrons oscillate between the two cylinder cathodes and alternately flow from the two cathodes. The sheath layer obtains energy to generate arc discharge, that is, hollow cathode discharge; high-concentration and high-activity nitrogen-containing substances are generated, which pass through the holes distributed on the small cylinder, rapidly saturate and react and diffuse on the surface of the workpiece to form a nitride layer; the specific details of nitriding The parameters can be adjusted according to the process requirements; the pressure is controlled within 200-2000Pa, the nitriding temperature is 450-580 degrees Celsius, and the nitriding time is within 2-20 hours;

D. Oxidation treatment

After the nitriding treatment is completed, close the ammonia cylinder and re-evacuate to about 10Pa. Then, open the oxygen cylinder and fill the furnace with oxygen, control the air pressure within 50-500Pa, and gradually adjust the voltage and current to control the oxidation. The temperature is 300-500 degrees Celsius, and the air pressure in the vacuum furnace is adjusted by the flowmeter to keep the double-layer cylinder to maintain the hollow cathode discharge; during the period, according to the actual situation, such as when the temperature drops, open the argon gas bottle and fill it with argon gas to let the argon gas cause the discharge. Sputtering, so as to increase the discharge intensity and maintain the temperature required for the oxidation of the workpiece; control the oxidation time to 10-150 minutes according to the process requirements;

E. Cooling stage

Evacuate the vacuum furnace into a low vacuum and turn off the power; the workpiece will be released when it cools down to 100 degrees Celsius with the vacuum furnace.

Compared with the prior art, the present invention has the following beneficial effects:

1. Because the present invention regenerates an oxide film on the surface of the nitrided layer through ion oxidation post-treatment, overcomes the loose defects generated after nitriding, and improves the surface corrosion resistance and wear resistance.

2. Since the invention uses the workpiece as the anode, it avoids the disadvantages of arcing on the surface caused by using the workpiece as the cathode in the traditional process, and the integrity and protection of the oxide film layer is good.

3. Since the present invention combines the advantages of plasma infiltration and vacuum gas infiltration, the aluminum sample substrate is connected to the wall of the vacuum furnace, that is, the workpiece is used as an anode for surface modification treatment. Through the placement of the hollow cathode device, the hollow cathode discharge is used to increase the discharge intensity and ionization rate, thereby producing a high-concentration, high-activity permeating substance, forming a modification with good corrosion resistance, high hardness, and good friction and wear performance on the surface. layer.

4. Since the present invention uses double-layer cylinders to realize hollow cathode discharge, the processing efficiency of nitriding and oxidation is improved.

5. Because the workpiece of the present invention reacts more rapidly with the O ion as the anode, the compactness of the oxide film layer, the structure of the oxide film is compact, compared with the single ion nitriding treatment, it can more effectively hinder the corrosion of the metal by the corrosion environment ,

6. Due to the placement of the hollow cathode auxiliary device, that is, the double-layer cylinder, the hollow cathode discharge is generated under the oxygen atmosphere, which improves the active oxygen species; at the same time, the sample is heated by the radiation of the double-layer cylinder, and the surface is heated evenly , thereby shortening the oxidation time.

7. In the present invention, insulating ceramic sheets are placed on the small cylinder, which can increase the concentration of active oxygen species around the workpiece, that is, in the large cylinder, so as to prevent the dissipation of active oxygen species.

Description of drawings

The present invention only has 1 accompanying drawing, wherein:

Fig. 1 is a structural schematic diagram of a combined nitriding and oxidation treatment device for the surface of low alloy steel.

In the figure: 1. furnace door, 2. air inlet, 3. ammonia cylinder, 4. oxygen cylinder, 5. argon cylinder, 6. power supply, 7. small cylinder, 8 large cylinder, 9. workpiece, 10 , stage, 11, support, 12, insulator, 13, S-type thermocouple, 14, vacuum pump, 15, insulating ceramic sheet.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings. As shown in Figure 1, a low-alloy steel surface nitriding and oxidation composite treatment device includes a vacuum furnace, an air intake system, a vacuum system, a power supply system, and a temperature measurement system. The furnace body and the furnace door 1 are composed; the air intake system includes an ammonia cylinder 3, an oxygen cylinder 4, an argon cylinder 5, a flow controller and an air inlet 2, and the air inlet 2 is installed on the vacuum furnace side; The power supply system adopts a pulse-charged DC high-voltage power supply or a DC sputtering high-voltage power supply; the temperature measurement system is a commonly used S-type thermocouple 13, which is installed at a position 2 to 4 cm away from the stage 10; the vacuum pumping system Including a vacuum pump 14 and its pipeline, the vacuum pump 14 is connected to the base of the vacuum furnace through the pipeline; a hollow cathode auxiliary device and a workpiece platform are installed in the described vacuum furnace, and the hollow cathode auxiliary device consists of two diameters Different small cylinders 7 and large cylinders 8 with holes are formed. The small cylinder 7 and the large cylinder 8 form a coaxial double-layer cylinder, which are located on the insulating ring 12 and are separated by the insulating ring 12. The small cylinder 7 and the large cylinder 8 are respectively connected to the cathode of the power supply 6, and the small cylinder 7 is placed with an insulating ceramic sheet 15; the workpiece platform includes a support 11 and a stage 10, and the support Seat 11 is located on the base of the vacuum furnace; the described object table 10 is made of stainless steel plate, located on the support 11, for placing the workpiece 9, the furnace wall of the described object table 10 and the vacuum furnace is respectively connected with the power supply 6 the anode connection. The support 11 is made of conductive material or insulating material. The small cylinder 7 and the large cylinder 8 are made of low carbon steel, the diameter of the small cylinder 7 is 350-400 mm, the diameter of the large cylinder 8 is 364-418 mm, and the average distribution diameter on the small cylinder 7 is 11-400 mm. 12mm holes, the hole spacing is 12-15mm; the distance between the large cylinder 8 and the small cylinder 7 is 7-9mm; the thickness of the insulating ceramic sheet 15 is 7-10mm, and its diameter is slightly larger than the diameter of the small cylinder 7 .

A kind of low alloy steel surface nitriding oxidation compound treatment method comprises the following steps:

A. Cleaning and loading of workpiece 9

Clean the surface of the workpiece 9 with an industrial cleaning agent, then charge the furnace, and place the workpiece 9 on the stage 10;

B. Vacuumizing and glowing

Start the vacuum pump 14 to pump air. When the vacuum degree in the vacuum furnace reaches 10-20Pa, open the ammonia cylinder 3, fill the purified ammonia gas through the air inlet 2, and adjust the flow rate of the ammonia gas to maintain the pressure in the vacuum furnace. At 133-1333Pa, turn on the power supply 6, so that the ammonia gas in the vacuum furnace is ionized under the action of a high-voltage electric field, resulting in a glow discharge effect;

C. Nitriding treatment

Adjust the distance between the small cylinder 7 and the large cylinder 8. After the small cylinder 7 and the large cylinder 8 are connected to the cathode power supply, adjust the air pressure in the vacuum furnace to generate a glow discharge, and the electrons oscillate between the cathodes of the two cylinders and Alternately obtain energy from the two cathode sheath layers to generate arc discharge, that is, hollow cathode discharge; generate high-concentration and highly active nitrogen-containing substances, which pass through the holes distributed on the small cylinder 7, rapidly saturate and react and diffuse on the surface of the workpiece 9 to form nitrides layer; the specific parameters of nitriding can be adjusted according to the process requirements; the pressure is controlled within 200-2000Pa, the nitriding temperature is 450-580 degrees Celsius, and the nitriding time is within 2-20 hours;

D. Oxidation treatment

After the nitriding treatment is completed, close the ammonia cylinder 3, and re-evacuate to about 10Pa. Then, open the oxygen cylinder 4, fill the furnace with oxygen, control the air pressure within 50-500Pa, and gradually adjust the voltage and current. Control the oxidation temperature at 300-500 degrees Celsius, adjust the air pressure in the vacuum furnace through a flowmeter, so that the double-layer cylinder maintains a hollow cathode discharge; during the period, according to the actual situation, such as when the temperature drops, open the argon cylinder 5 and fill it with argon to let Argon gas causes sputtering, thereby increasing the discharge intensity and maintaining the temperature required for the oxidation of the workpiece; the oxidation time is controlled to be 10 to 150 minutes according to the process requirements;

E. Cooling stage

The vacuum furnace is evacuated into a low vacuum, and the power is turned off; when the workpiece 9 is cooled to 100 degrees Celsius with the vacuum furnace, it comes out of the furnace.

Claims (4)

1. a nitriding and oxidizing surface of low-alloy steel composite handling arrangement comprises vacuum oven, inlet system, pumped vacuum systems, power supply system, temp measuring system, and described vacuum oven is that equipment is oozed in the ion expansion, is made up of vacuum furnace body and fire door (1); Described inlet system comprises ammonia bottle (3), oxygen cylinder (4), argon bottle (5), flow director and inlet mouth (2), and inlet mouth (2) is installed in the vacuum furnace side; Described power supply system adopts arteries and veins to fill DC high-voltage power supply or d.c. sputtering high-voltage power supply; Described temp measuring system is installed in apart from the position of Stage microscope (10) 2～4cm for S type thermopair (13) commonly used; Described pumped vacuum systems comprises vacuum pump (14) and pipeline thereof, and described vacuum pump (14) links to each other with the base of vacuum oven by pipeline; It is characterized in that: hollow cathode supplementary unit and work piece platform are installed in the described vacuum oven, described hollow cathode supplementary unit and little cylinder (7) and large cylinder (8) that have hole different by two diameters are formed, described little cylinder (7) and large cylinder (8) constitute the coaxial double-layer cylinder, be positioned on the dead ring (12), and by dead ring (12) isolation, described little cylinder (7) is connected with the negative electrode of power supply (6) respectively with large cylinder (8), and described little cylinder (7) is placed with insulating ceramic film (15); Described work piece platform comprises bearing (11) and Stage microscope (10), and described bearing (11) is positioned on the vacuum oven base; Described Stage microscope (10) is made by stainless steel plate, is positioned on the bearing (11), is used for place work piece (9), and the furnace wall of described Stage microscope (10) and vacuum oven is connected with the anode of power supply (6) respectively.

2. a kind of nitriding and oxidizing surface of low-alloy steel composite handling arrangement according to claim 1 is characterized in that: described bearing (11) is made by electro-conductive material or insulating material.

3. a kind of nitriding and oxidizing surface of low-alloy steel composite handling arrangement according to claim 1, it is characterized in that: described little cylinder (7) and large cylinder (8) are made by soft steel, the diameter of little cylinder (7) is 350～400mm, the diameter of large cylinder (8) is 364～418mm, be evenly distributed the hole that diameter is 11～12mm on the little cylinder (7), the hole spacing is 12～15mm; Keeping the large cylinder (8) and the spacing of little cylinder (7) is 7～9mm; Described insulating ceramic film (15) thickness is 7～10mm, and its slightly larger in diameter is in the diameter of little cylinder (7).

4. nitriding and oxidizing surface of low-alloy steel compounding method is characterized in that: may further comprise the steps:

The cleaning and the shove charge of A, workpiece (9)

With industrial cleaning agent cleaning workpiece (9) surface, carry out shove charge then, workpiece (9) is placed on the Stage microscope (10);

B, vacuumize, build-up of luminance

Starting vacuum pump (14) bleeds, when vacuum tightness reaches 10～20Pa in the vacuum oven, open ammonia bottle (3), charge into the ammonia that purified by inlet mouth (2), regulate the flow of ammonia, make the pressure in the vacuum oven remain on 133～1333Pa, opening power (6), make the ammonia in the vacuum oven under the effect of high-voltage electric field, ionization take place, produce the glow discharge effect;

C, nitriding treatment

Regulate the spacing between little cylinder (7) and the large cylinder (8), at little cylinder (7) and large cylinder (8) with after cathode power is connected, regulate the vacuum oven internal gas pressure, produce glow discharge, electronics shakes between two cylinder negative electrodes and alternately obtains energy from two cathode sheath layers, and producing arc discharge is hollow cathode discharge; Produce high density, high reactivity nitrogenous substances, go up the hole that distributes by little cylinder (7), saturated fast and reaction diffusion forms nitride layer on workpiece (9) surface; The concrete parameter of nitrogenize can be regulated according to the processing requirement condition; Pressure is controlled in 200～2000Pa, and nitriding temperature is 450～580 degrees centigrade, and nitridation time is in 2～20 hours;

D, oxide treatment

After nitriding treatment is finished, close ammonia bottle (3), again be evacuated down to and reach about 10Pa, thereafter, open oxygen cylinder (4), in stove, charge into oxygen, control air pressure is in 50～500Pa, and progressively regulating voltage, electric current, and the controlled oxidation temperature is at 300～500 degrees centigrade, regulate the vacuum oven internal gas pressure by under meter, make double-layered cylinder keep hollow cathode discharge; In the time of can descending according to practical situation such as temperature during this time, open argon bottle (5), charge into argon gas, allow argon gas cause sputter, thereby increase strength of discharge, it is temperature required to keep the workpiece oxidation; According to the processing requirement controlled oxidation time be 10～150 minutes;

E, cooling stages

With being pumped into rough vacuum in the vacuum oven, turn off power supply; Treat to come out of the stove when workpiece (9) cools off to 100 degrees centigrade with vacuum oven.