CN108130505A - A kind of method that beam-plasma alloying prepares high-entropy alloy coating - Google Patents

Abstract

The invention discloses a kind of methods that Cast Iron Surface beam-plasma alloying forms carbide enhancing high-entropy alloy composite coating; using the mixed-powder of the beam-plasma a certain proportion of Ni Cr B Si powder of heating alloying, Mn powder, Cu powder, vanadium iron powder, Cr powder composition under the protection of Cast Iron Surface argon gas; on the basis of Cast Iron Surface melts on a small quantity, form by VC, Cr₇C₃The CrCuFeMnNi high-entropy alloy coatings of enhancing.There is the hesitation of high-entropy alloy, VC, Cr in alloy process₇C₃There is the advantages of crystal grain is tiny, and coating layer thickness is thicker.

Description

A method for preparing high-entropy alloy coatings by plasma beam alloying

technical field

The invention belongs to the field of high-energy beam surface treatment, in particular to a method for preparing a wear-resistant composite coating by plasma beam alloying.

Background technique

Cast iron has good casting performance, low melting point, good fluidity and low manufacturing cost, so it is widely used, but its wear resistance is poor, and it is often necessary to improve the wear resistance of some surfaces or parts of cast iron parts. Cast iron contains a lot of graphite elements, and ordinary high-energy beams are used for surface alloying treatment. CO gas is easy to be generated during the alloying process, and more pores will be formed when the coating cannot be discharged in time, and the solid solution of C It also causes white iron to form during cooling, making it brittle and hard. In addition, due to the high-temperature melting of the substrate during the alloying process, the composition of the composite coating will be diluted and the performance of the coating will be reduced.

High-entropy alloys are alloys composed of more than five elemental components alloyed according to the equiatomic ratio or close to the equiatomic ratio. They have excellent mechanical properties unmatched by some traditional alloys, such as high wear resistance and corrosion resistance, high strength, High hardness, high toughness, etc., making it one of the choices for making coatings. Considering the graphite contained in cast iron, in order to form carbides in the coating, a certain amount of Cr is selected in the alloying material, which is not only conducive to the formation of Cr carbides, but also can reduce the pores caused by the formation of CO, and at the same time, avoid cast iron in Rapid cooling after heating will lead to white mouth. Add certain austenitizing elements Mn and Cu to promote the formation of austenite structure. In order to further reduce the formation of CO and refine the grain, add a small amount of vanadium iron powder. Finally, due to the high melting point of Ni powder, Ni-Cr-B-Si alloy powder was added to the alloy powder as a substitute for Ni. In conclusion, CrCuFeMnNi high-entropy alloy coatings reinforced by vanadium carbide and chromium carbide can be formed.

Plasma beam is a high-energy beam with highly concentrated arc energy and low cost. By mechanically compressing the arc, the temperature of the arc column can reach 10000-24000K, and it has a certain "digging" effect on the alloyed substrate, which is conducive to the uniformity of the coating , but will melt part of the cast iron substrate resulting in dilution of the original coating composition.

Contents of the invention

Considering that the main components in cast iron are Fe and C, the coating will be diluted due to the melting of the cast iron matrix during the high-energy beam alloying process. By melting the appropriate components and part of the cast iron surface, carbides are formed on the surface to enhance the high entropy Alloy composite coating is beneficial to improve the wear resistance of cast iron and reduce the formation of pores. The preparation method adopted by the present invention to solve its technical problems comprises the following process steps:

Step 1. Select the surface of the iron casting to be strengthened as the matrix, use a grinding wheel or sandpaper to polish the surface of the parts to be processed to remove rust, and use alcohol or acetone to remove the oil on the surface of the parts;

Step 2: Mix Ni-Cr-B-Si powder, Mn powder, Cu powder, vanadium iron powder, and Cr powder according to a certain proportion, and use a ball mill to perform ball milling and mixing. The particle size of the powder used is 40-260 μm; wherein Ni- The mass percentages of Cr-B-Si powder, Mn powder, Cu powder, vanadium iron powder and Cr powder are: 32~38: 18~25: 18~25: 8~10: 8~12; the Ni-Cr -The mass percentage of B-Si component is Cr: 16~18, B: 2.5~4.5, Si: 3~4.5, and the rest is Ni; the purity of Cu powder, Mn powder and Cr powder is higher than 99.5%; The mass of vanadium in it is 49~51%, the rest is Fe, and the purity is higher than 99%. Ball milling is to use steel ball milling jars for ball milling and mixing, in which the mass ratio of balls to metal powder is 2.7~3.2:1. After sealing, open the vacuum valve to evacuate for 20~30 minutes, put the ball mill jars into the planetary ball mill. 260~300 r/min, reverse frequency 30~45 Hz, ball mill mixing time is 60~80 minutes.

Step 3. Mix the mixed powder and pressure-sensitive adhesive in a weight ratio of 1:1.2~1.5 to make alloyed powder, and coat it on the surface of the cast iron substrate with a coating thickness of 1-4mm and a width of 6-7mm, at 100 Dry at ~120°C for 1.5~2h.

Step 4: The alloying powder to be alloyed is heated by plasma beam to melt and realize alloying, and the wear-resistant coating is obtained after cooling. Among them, argon is used as the protective gas and ionized gas, the alloying current is 90-150 A, the working voltage is 30-40 V, the scanning speed is 3-6 mm/s, and the flow rate of argon as the protective gas is 0.9~1.5m ³ / h, the flow rate of argon as ionization is 0.7~1.3m ³ /h, and the distance between the nozzle and the surface to be treated is 0.7~1.3cm.

The beneficial effects of the present invention are:

(1) The process of the present invention adopts high-entropy alloy as the matrix of the wear-resistant coating, which can make full use of its unique characteristics of slow diffusion rate and insensitivity to composition changes, so that the coating has higher toughness, strength, and wear resistance. Abrasive.

(2) The present invention uses the addition of carbide-forming elements containing Cr and V, which reduces the formation of CO and is beneficial to reduce the pores in the coating. The addition of austenitization forming elements Ni, Cu, and Mn not only reduces the formation of white spots at the cast iron interface, but also forms a face-centered cubic structure (FCC), which has high toughness and strength. Alloying Ni-Cr-B-Si, Mn and Cu with lower melting point is beneficial to increase the thickness of the coating. Among them, since cast iron contains a large amount of graphite and a certain amount of carbide-forming elements, it is beneficial to reduce the formation of pores.

(3) The reinforcing phases of the present invention mainly include (Cr, Fe) ₇ C ₃ and VC. Due to the hysteretic diffusion effect inherent in high-entropy alloys, the size of the primary (Cr, Fe) ₇ C ₃ and VC during the alloying process Reduction is conducive to the improvement of wear resistance.

Detailed ways

Example 1:

Step 1. Select HT250 as the substrate, use a grinding wheel or sandpaper to polish the surface of the parts to be processed to remove rust, and use alcohol or acetone to remove the oil on the surface of the parts;

Step 2: Mix Ni-Cr-B-Si powder, Mn powder, Cu powder, vanadium iron powder, and Cr powder according to a certain ratio to form a mixed powder, and use a ball mill to perform ball milling and mixing, and the particle size of the powder used is 40-120 μm; wherein Ni- The mass percent of Cr-B-Si powder, Mn powder, Cu powder, vanadium iron powder and Cr powder is: 32:25:25:10:8; the mass percent of the Ni-Cr-B-Si component is Cr : 16~18, B: 2.5~4.5, Si: 3~4.5, the rest is Ni; the purity of Cu powder, Mn powder, Cr powder is higher than 99.5%; the mass of vanadium in vanadium iron powder is 49~51% , and the rest is Fe with a purity higher than 99%. Ball milling and mixing is carried out by using a steel ball milling jar, in which the mass ratio of balls to metal powder is 3:1. After sealing, open the vacuum valve to evacuate for 25 minutes, and put the ball milling jar into a planetary ball mill at a speed of 300 r/ min, the inverted frequency is 45 Hz, and the ball milling time is 80 minutes.

Step 3. Mix the mixed powder and pressure-sensitive adhesive in a weight ratio of 1:1.4 to make alloyed powder, and coat it on the surface of the cast iron substrate with a coating thickness of 4mm and a width of 6mm, and dry at 100-120°C for 2 hours .

Step 4: The alloying powder to be alloyed is heated by plasma beam to melt and realize alloying, and the wear-resistant coating is obtained after cooling. Among them, argon is used as the protective gas and ionized gas, the alloying current is 150 A, the working voltage is 30 V, the scanning speed is 6 mm/s, the flow rate of argon as the protective gas is 1.5m ³ /h, and the flow rate of argon as the ionization It is 1.3m ³ /h, and the distance between the nozzle and the surface to be treated is 1cm.

Experiments have shown that high-entropy alloy coatings of granular VC and rod-shaped (Cr, Fe) ₇ C ₃ reinforced CrCuFeMnNi are formed on the surface of cast iron, in which the diameter of Cr ₇ C ₃ is less than 1.5 μm, and the thickness of the coating is about 450μm, the wear resistance has increased by more than 3.5 times.

Example 2:

Step 1. Select the surface of Q600 as the substrate, use a grinding wheel or sandpaper to polish the surface of the parts to be processed to remove rust, and use alcohol or acetone to remove the oil on the surface of the parts;

Step 2: Mix Ni-Cr-B-Si powder, Mn powder, Cu powder, vanadium iron powder, and Cr powder according to a certain proportion, and use a ball mill to perform ball milling and mixing. The particle size of the powder used is 140-260 μm; wherein Ni- The mass percent of Cr-B-Si powder, Mn powder, Cu powder, vanadium iron powder, and Cr powder is: 38:18:25:10:9; the mass percent of the Ni-Cr-B-Si component is Cr : 16~18, B: 2.5~4.5, Si: 3~4.5, the rest is Ni; the purity of Cu powder, Mn powder, Cr powder is higher than 99.5%; the mass of vanadium in vanadium iron powder is 49~51% , and the rest is Fe with a purity higher than 99%. Ball mill mixing is carried out by using a steel ball mill jar, in which the mass ratio of balls to metal powder is 2.7:1. After sealing, open the vacuum valve to evacuate for 20 minutes, and put the ball mill jar into a planetary ball mill at a speed of 260 r/ min, the inverted frequency is 30 Hz, and the ball milling time is 60 minutes.

Step 3: Mix the mixed powder and pressure-sensitive adhesive in a weight ratio of 1:1.2 to make alloyed powder, which is coated on the surface of the steel substrate with a coating thickness of 1mm and a width of 7mm, and is dried at 120°C for 1.5.

Step 4: The alloying powder to be alloyed is heated by plasma beam to melt and realize alloying, and the wear-resistant coating is obtained after cooling. Among them, argon is used as the protective gas and ionized gas, the alloying current is 90 A, the working voltage is 40 V, the scanning speed is 3 mm/s, the flow rate of argon as the protective gas is 0.9 ³ /h, and the flow rate of argon as the ionization is 0.7 m ³ /h, the distance between the nozzle and the surface to be treated is 0.7cm.

Experiments have shown that VC and rod-shaped (Cr, Fe) ₇ C ₃ reinforced CrCuFeMnNi high-entropy alloy coatings are formed on the surface of cast iron, where the diameter of Cr ₇ C ₃ is less than 1.5 μm, and the thickness of the coating is about 650 μm , Wear resistance increased by more than 3.2 times.

Example 3:

Step 1. Select HT350 as the substrate, use a grinding wheel or sandpaper to polish the surface of the parts to be processed to remove rust, and use alcohol or acetone to remove the oil on the surface of the parts;

Step 2: Mix Ni-Cr-B-Si powder, Mn powder, Cu powder, vanadium iron powder, and Cr powder according to a certain proportion, and use a ball mill to perform ball milling and mixing. The particle size of the powder used is 40-260 μm; wherein Ni- The mass percent of Cr-B-Si powder, Mn powder, Cu powder, vanadium iron powder, and Cr powder is: 35:25:18:10:12; the mass percent of the Ni-Cr-B-Si component is Cr : 16~18, B: 2.5~4.5, Si: 3~4.5, the rest is Ni; the purity of Cu powder, Mn powder, Cr powder is higher than 99.5%; the mass of vanadium in vanadium iron powder is 49~51% , and the rest is Fe with a purity higher than 99%. Ball mill mixing is carried out by using a steel ball mill jar for ball mill mixing, in which the mass ratio of balls to metal powder is 3.2:1. After sealing, open the vacuum valve to evacuate for 30 minutes, and put the ball mill jar into a planetary ball mill at a speed of 260 r/ min, the inverted frequency is 30 Hz, and the ball milling time is 60 minutes.

Step 3: Mix the mixed powder and pressure-sensitive adhesive in a weight ratio of 1:1.5 to make alloyed powder, which is coated on the surface of the cast iron substrate with a coating thickness of 2mm and a width of 6mm, and finally baked at 100°C for 1.5.

Step 4: The alloying powder to be alloyed is heated by plasma beam to melt and realize alloying, and the wear-resistant coating is obtained after cooling. Among them, argon is used as the protective gas and ionized gas, the alloying current is 140 A, the working voltage is 35 V, the scanning speed is 4.5 mm/s, the flow rate of argon as the protective gas is 1.2 m ³ /h, and the flow rate of argon as the ionization is 1.2m ³ /h, the distance between the nozzle and the surface to be treated is 1cm.

Experiments have shown that VC and rod-shaped (Cr, Fe) ₇ C ₃ reinforced CrCuFeMnNi high-entropy alloy coatings are formed on the surface of cast iron, in which the diameter of Cr ₇ C ₃ is less than 1.5 μm, and the thickness of the coating is about 550 μm , Wear resistance increased by more than 3.5 times.

Claims (5)

1. a kind of method that beam-plasma alloying prepares high-entropy alloy coating, which is characterized in that the production method includes Following processing steps：

Step 1: the Iron Casting Surface that will be need to strengthen is chosen as matrix, the table for parts to be processed of being polished with grinding wheel or sand paper Face is derusted, and the greasy dirt of component surface is removed with alcohol or acetone；

Step 2: Ni-Cr-B-Si powder, Mn powder, Cu powder, vanadium iron powder, Cr powder are formed mixed-powder, and use ball by a certain percentage Grinding machine carries out ball milling mixing, and powder diameter used is at 40-260 μm；

Step 3: mixed-powder and pressure sensitive adhesive are pressed 1:1.2 ~ 1.5 weight ratio, which are mixed, treats alloyed powder, is coated to Cast iron matrix surface, coating thickness is 0.8 ~ 1.2cm, and is dried；

It is melted Step 4: treating alloyed powder heating using beam-plasma and realizes alloying, be wear-resisting painting after cooling Layer.

2. the method that a kind of beam-plasma alloying according to claim 1 prepares high-entropy alloy coating, it is characterised in that： The Ni-Cr-B-Si powder, Mn powder, Cu powder, vanadium iron powder, Cr powder mass percent be：32~38：18~25：18~25：8~ 10：8~12；The mass percent of the Ni-Cr-B-Si ingredients is Cr：16 ~ 18, B：2.5 ~ 4.5, Si：3 ~ 4.5, remaining is Ni；Cu powder, Mn powder, Cr powder purity be higher than 99.5%；The quality containing vanadium is 49 ~ 51% in vanadium iron powder, remaining is Fe, purity Higher than 99%.

3. the method that a kind of beam-plasma alloying according to claim 1 prepares high-entropy alloy coating, it is characterised in that： The ball milling mixing is to carry out ball milling mixing using steel ball grinder, and abrading-ball therein is 2.7 ~ 3.2 with metal powder mass ratio: 1, vacuum valve is opened after sealing and is vacuumized 20 ~ 30 minutes, ball grinder is put into planetary ball mill, rotating speed is 260 ~ 300 r/ Min swings to 30 ~ 45 Hz of frequency, and it is 60 ~ 80 minutes to carry out the ball mill mixing time.

4. the method that a kind of beam-plasma alloying according to claim 1 prepares high-entropy alloy coating, it is characterised in that The coating thickness is 1-4mm, width 6-7mm, and 1.5 ~ 2h is dried at 100 ~ 120 DEG C.

5. the method that a kind of beam-plasma alloying according to claim 1 prepares high-entropy alloy coating, it is characterised in that The alloying technology parameter is：Argon gas is as protection gas and ionized gas, and alloy galvanic current is 90-150 A, operating voltage 30-40 V, sweep speed are 3-6 mm/s, and argon gas is 0.9 ~ 1.5m as the flow of protection gas³/ h, stream of the argon gas as ionization It measures as 0.7 ~ 1.3m³/ h, distance of the nozzle away from surface to be treated are 0.7 ~ 1.3cm.