CN104278234B - Preparation technology for self-lubricating coating with wide temperature range of room temperature to 800 DEG C - Google Patents

Abstract

The invention discloses a preparation technology for a self-lubricating coating with a wide temperature range of room temperature to 800 DEG C. An arc ion plating method is employed for preparing a chrome oxide coating, and the prepared chrome oxide coating has relatively small friction coefficient (0.15-0.4) and relatively low wear rate at the wide temperature range of room temperature to 800 DEG C, especially at 800 DEG C, the friction coefficient is about 0.15 and the wear rate is about 10-7 mm＜3＞/Nm. Because of the good mechanical properties and tribology performances, the chrome oxide coating is applied to sealing of foil sheets of aero-engines, gas bearings and other friction moving parts working at the wide temperature range of room temperature to 800 DEG C.

Description

Preparation technology of a self-lubricating coating in a wide temperature range from room temperature to 800 °C

technical field

The invention relates to a preparation technology of a chromium oxide coating with self-lubricating properties in a wide temperature range from room temperature to 800°C.

Background technique

Considering the demand of high-tech industries such as aerospace, smelting and chemical industry, and thermonuclear for solid lubricating coatings in a wide temperature range, researchers have gradually explored them, but so far no single coating has been found that can meet the requirements of solid lubrication coatings in the wide temperature range. It has a low wear rate and a small friction coefficient in a wide temperature range from room temperature to high temperature, so its research and development has important scientific value and application prospects. Coating deposition technology mainly includes vapor deposition technology, thermal spraying technology, laser cladding technology, etc., especially the application of vapor deposition technology and thermal spraying technology is more mature.

Arc ion plating is a typical physical vapor deposition method to prepare thin films. The principle is that in the vacuum chamber, an electric field is applied between the substrate and the evaporation source. When the pressure in the chamber is appropriate, glow discharge or arc discharge will be generated between the evaporation source and the substrate. During the collision with electrons, gas ions and The ions of the target, which are accelerated in the electric field and fly to the substrate, then condense under the influence of ion bombardment to form a thin film. Compared with magnetron sputtering, it has the following advantages: (1) The combination of the film and the substrate is better; (2) The deposition rate of the film is faster; (3) The coating of the film is better; (4) The density of the film is improved ; (5) High metal ionization rate, which is beneficial to the uniformity of the film; (6) One arc is multi-purpose, not only a heating source, but also a pre-bombardment purification source and ionization source, (7) High utilization rate of the target, etc.

Chromium oxide has long been considered one of the hardest oxides, and it has good corrosion resistance and unique optical properties, and is widely used in solar light absorbing materials and photocopying molds. However, at present, non-magnetron sputtering methods are mostly used to prepare chromium oxide coatings, which have poor wrapping properties for parts with complex shapes and low oxygen content, which affects the tribological properties of the coatings and limits the chromium oxide coatings. Layer application in a wide temperature range.

Contents of the invention

The main purpose of the present invention is to provide a preparation technology of a coating material with self-lubricating properties in a wide temperature range from room temperature to 800°C.

The purpose of the present invention can be achieved through the following technical solutions:

A preparation technology for a self-lubricating coating in a wide temperature range from room temperature to 800°C, which is prepared by arc ion plating, and is characterized in that the coating deposition process of this method is completed in a vacuum chamber of a coating machine equipped with an arc, specifically The steps are:

A. Activate and clean the surface: put a smooth and clean metal substrate in the cavity, vacuum below 1.5×10 ^-2 Pa, pass in argon gas as the ionization gas, turn on the pulse bias power supply, and glow discharge to generate plasma Body, activate and clean the surface of the substrate;

B. Preparation of the transition layer: After cleaning, use the method of arc ion plating to deposit the chromium transition layer first, select the chromium column target as the arc ion plating target material, use argon as the ionization gas, add a negative bias to the substrate, and deposit the chromium transition layer close after layer;

C. Deposition of chromium oxide coating: The arc ion plating target is still a chromium column target, and then oxygen is introduced to control the structure of the coating by controlling the flow ratio of nitrogen and oxygen, as well as the current and the bias voltage applied to the substrate;

D. Coating post-treatment: Carry out annealing treatment, and then naturally cool to room temperature.

In step A, the metal substrate is selected from M2 high-speed steel, nickel-based alloy steel, stainless steel or aluminum alloy, and the range of plasma activation process parameters is: cavity pressure 0.4-2.0Pa, bias voltage -100V--1000V.

In step B, the process parameters of the chromium transition layer are in the range of: chamber pressure 0.2-1.0 Pa, sputtering current 1-200 A, pulse bias voltage -50-500 V, transition layer thickness 30-500 nm.

In step C, the range of process parameters for the chromium oxide layer is: chamber pressure 0.2-1.0Pa, O2/Ar flow ratio 1:5-5:1, sputtering current 1-200 A, pulse bias -50-- 500V, coating thickness 0.5~5um.

In step D, the range of annealing process parameters is: annealing temperature 200-1000°C, heating rate 1-20°C/min, holding time 0.5-5h.

The main components of the film are Cr and Cr ₂ O ₃ , and its cross-sectional structure is shown in Figure 1. The Cr transition layer is mainly to increase the bonding force between the film and the substrate in a wide temperature range, and Cr2O3 is its wear-reducing and wear-resistant phase.

The main performance index of product of the present invention is as shown in the following table:

The invention adopts the method of arc ion plating to prepare the chromium oxide coating. Compared with the chromium oxide coating prepared by magnetron sputtering, the chromium oxide coating prepared by the arc ion plating method has increased the wrapping ability for complex samples, and the bonding force between the coating and the substrate is stronger, and the coating The oxygen content is also increased, thereby improving the mechanical properties, oxidation resistance and tribological properties of the coating. After investigation, the chromium oxide coating prepared by arc ion plating method has a small friction coefficient (0.15-0.4) and a low wear rate in the wide temperature range from room temperature to 800 °C, especially at 800 °C. At around 0.15, the wear rate is also around 10 ^-7 mm ³ /Nm. In view of its good mechanical properties and tribological properties, chromium oxide coatings can be applied to foil seals of aeroengines, gas bearings and other frictional moving parts that work in a wide temperature range from room temperature to 800 °C.

Description of drawings

Fig. 1 is a scanning electron microscope topography diagram of a section of a Cr ₂ O ₃ thin film.

Figure 2 shows the friction coefficient of Cr ₂ O ₃ coating from room temperature to 800°C.

detailed description

Example 1:

A. Sample pretreatment: The stainless steel polished to the mirror surface was ultrasonically cleaned with distilled water and acetone for 10 minutes, then dried with nitrogen and placed in the deposition chamber. Evacuate the air pressure in the vacuum chamber to below 1.5×10 ^-2 Pa, and inject high-purity argon until the air pressure is 1.5 Pa. Turn on the pulse bias power supply, adjust the voltage value to -500 V, and perform argon plasma bombardment cleaning for 20 min.

B. Deposit chromium transition layer: adjust the flow rate of argon gas to maintain the chamber pressure at about 0.45Pa, turn on the column arc power supply, adjust the current to 90A, and the bias voltage to -200V, and turn it off when the transition layer is about 200nm deposited.

C. Deposit chromium oxide layer: feed a mixed gas of high-purity argon and oxygen to maintain the chamber pressure at about 0.45Pa, control the flow ratio of argon and oxygen to 1:2, turn on the column arc power supply, and adjust the current to 90A, the bias voltage is -200V, after deposition for about 2 hours, cool down, and when the temperature drops below 50°C, release the vacuum and open the cavity for sampling.

D. Sample post-treatment: The sample is kept in a muffle furnace at 400°C for 2 hours.

Example 2:

A. Sample pretreatment: The aluminum alloy polished to the mirror surface was ultrasonically cleaned with distilled water and acetone for 10 minutes, then dried with nitrogen and placed in the deposition chamber. Evacuate the air pressure in the vacuum chamber to below 1.5×10 ^-2 Pa, and inject high-purity argon until the air pressure is 1.0 Pa. Turn on the pulse bias power supply, adjust the voltage value to -400 V, and carry out argon plasma bombardment cleaning for 15 min.

B. Deposit chromium transition layer: adjust the flow of argon gas to maintain the chamber pressure at about 0.45Pa, turn on the column arc power supply, adjust the current to 100A, and the bias voltage to -300V, and turn it off when the transition layer is about 200nm deposited.

C. Deposit chromium oxide layer: feed a mixed gas of high-purity argon and oxygen to maintain the chamber pressure at about 0.45Pa, control the flow ratio of argon and oxygen to 1:1, turn on the column arc power supply, and adjust the current to 100A, the bias voltage is -300V, after deposition for about 2 hours, cool down, and when the temperature drops below 50°C, release the vacuum and open the cavity for sampling.

D. Sample post-treatment: The sample is kept in a muffle furnace at 500°C for 3 hours.

Example 3:

A. Sample pretreatment: The high-temperature steel polished to the mirror surface was ultrasonically cleaned with distilled water and acetone for 10 minutes, then dried with nitrogen and placed in the deposition chamber. Evacuate the air pressure in the vacuum chamber to below 1.5×10 ^-2 Pa, and inject high-purity argon until the air pressure is 2.0 Pa. Turn on the pulse bias power supply, adjust the voltage value to -700 V, and perform argon plasma bombardment cleaning for 50 min.

B. Deposit chromium transition layer: adjust the flow of argon gas to maintain the chamber pressure at about 0.45Pa, turn on the column arc power supply, adjust the current to 80A, and the bias voltage to -400V, and turn it off when the transition layer is about 200nm deposited.

C. Deposit chromium oxide layer: feed a mixed gas of high-purity argon and oxygen to maintain the chamber pressure at about 0.45Pa, control the flow ratio of argon and oxygen to 2:1, turn on the column arc power supply, and adjust the current to 50A, the bias voltage is -400V, after deposition for about 2 hours, cool down, and when the temperature drops below 50°C, release the vacuum and open the cavity for sampling.

D. Sample post-treatment: The sample is kept in a muffle furnace at 800°C for 1 hour.

Claims (3)

1. the technology of preparing of the wide temperature range self-lubricating coat in use of a kind of room temperature to 800 DEG C, using the method preparation of arc ion plating, it is special Levy and be that the deposition process of the method coating is to complete in the vacuum cavity of coating machine being furnished with electric arc, concretely comprises the following steps：

A, activation cleaning surface：Smooth, clean metallic substrates are placed within cavity, vacuumize 1.5 × 10^-2Below Pa, leads to Enter argon gas as ionization of gas, open pulsed bias power supply, glow discharge produces plasma, substrate surface is carried out with activation clear Wash；

B, transition zone preparation：After cleaning finishes, using the method deposition chromium transition zone first of arc ion plating, made from chromium post target For arc ion plating target, using argon gas as ionization of gas, the additional back bias voltage of matrix, close after deposition chromium transition zone；Described chromium Transition zone process parameters range is：Cavity air pressure 0.2～1.0Pa, sputtering current 1～200 A, pulsed bias -50～-500V, Transition region thickness 30～500 nm；

C, deposited oxide chrome coating：Arc ion plating target selects to be still chromium post target, then is passed through oxygen, by control argon gas and The size that the flow-rate ratio of oxygen and electric current and substrate are biased controls the structure of coating；Described chromium oxide layer technological parameter model Enclose for：Cavity air pressure 0.2～1.0Pa, O₂/ Ar flow-rate ratio is 1:2～2:1, sputtering current 1～200 A, pulsed bias -50～- 500V, 0.5～5 μm of coating layer thickness；

D, coating post processing：Made annealing treatment, then naturally cooled to room temperature.

2. the technology of preparing of the wide temperature range self-lubricating coat in use of room temperature as claimed in claim 1 to 800 DEG C is it is characterised in that in step In rapid A, metallic substrates are selected from M2 high-speed steel, Nickel-Based Steel, stainless steel or aluminium alloy, plasma-activated process parameters range For：Cavity air pressure 0.4～2.0Pa, biases -100V～-1000V.

3. the technology of preparing of the wide temperature range self-lubricating coat in use of room temperature as claimed in claim 1 to 800 DEG C is it is characterised in that in step In rapid D, parameter and annealing scope is：200～1000 DEG C of annealing temperature, 1～20 DEG C/min of programming rate, temperature retention time is 0.5～5h.