Method of manufacturing a ring insert and an aluminum piston

Abstract

This invention relates to the field of cast iron alloy technology and provides a method for preparing an insert ring, comprising the following steps: S1 mixing raw materials according to the component ratio of the insert ring substrate and then melting them to obtain an insert ring molten metal; S2 casting the insert ring molten metal, demolding it from the cylinder to obtain a tubular insert ring casting blank; S3 machining the tubular insert ring casting blank to obtain a shaped insert ring; S4 sequentially sandblasting and spraying the shaped insert ring to form an insert ring with an Al-Si alloy layer. This invention provides a method for preparing an insert ring, which obtains an insert ring with an Al-Si coating through centrifugal casting, machining, sandblasting, and spraying processes. The insert ring prepared by this invention forms an Al-Si coating at the junction with the aluminum piston. This coating is tightly bonded to the insert ring substrate and the aluminum piston, making the bonding force between the insert ring and the aluminum piston stronger, improving the oxide scale problem caused by high-temperature aluminization, and enhancing the resistance to thermal fatigue.

Description

Technical Field

[0001] This invention relates to the field of cast iron alloy technology, and more particularly to a method for preparing an insert ring and an aluminum piston. Background Technology

[0002] The piston is one of the most demanding core components in an internal combustion engine. Its top surface is subjected to the scouring of transient high-temperature combustion gases, and it slides at high speed within the cylinder, enduring cyclically alternating mechanical and thermal loads. To reduce reciprocating inertial forces and improve heat dissipation, modern pistons are generally made of aluminum alloys, especially aluminum-silicon cast aluminum alloys, which have low density, good thermal conductivity, and excellent casting and machining properties. However, aluminum alloys have low hardness and poor wear resistance. Their strength and modulus of elasticity decrease sharply above 200°C, and their mechanical strength at around 330°C is only about half that at room temperature. Furthermore, they have a high coefficient of linear expansion and insufficient resistance to high-temperature creep.

[0003] To overcome the physical limitations of aluminum piston material itself, an insert ring is added to the first ring groove of the aluminum piston. The strength and hardness of the cast iron insert ring are much higher than those of the aluminum matrix. At the same time, it can withstand the scouring of high temperature and high pressure combustion gases, overcome harsh working conditions such as wear and deformation, and high temperature oxidation, and improve the overall service life of the piston.

[0004] Currently, the cast iron insert undergoes an aluminizing treatment before being cast with the aluminum alloy substrate, primarily using the molten aluminum infiltration method. This method forms a uniform aluminized layer on the surface of the insert, with the core purpose of resolving the bonding issue between the cast iron insert and the aluminum alloy substrate, preventing the insert from loosening and cracking under the enormous explosive pressure generated during combustion. However, the aluminizing process currently faces challenges in process control and is prone to oxide scale defects, leading to bonding failure.

[0005] Therefore, providing a method for preparing the insert ring of an aluminum piston material is of great significance. Summary of the Invention

[0006] The technical problem solved by this invention is to provide a method for preparing an insert ring. The insert ring prepared by the method provided in this application has an Al-Si coating on its surface. The coating is tightly bonded to the insert ring body and the piston body, which makes the bonding force between the insert ring and the aluminum piston stronger, improves the oxide scale problem of high-temperature aluminizing, and enhances the fatigue resistance of the aluminum piston.

[0007] In view of this, this application provides a method for preparing a setting ring, comprising the following steps: S1. The raw materials are mixed and smelted according to the composition ratio of the ring insert matrix to obtain the ring insert molten metal; the composition of the ring insert matrix, by mass percentage, includes: C: 2.0~3.0%, Si: 1.0~2.8%, Mn: 0.5~1.5%, P: ≤0.2%, S: ≤0.1%, Cr: ≤2.5%, Cu: 5.0~8.0%, Ni: 12~17.5%, with the balance being Fe; S2. The molten metal inlaid with the ring is poured, and after demolding and exiting the cylinder, a tubular inlaid ring casting blank is obtained. S3. The tubular inlay casting blank is machined to obtain the shaped inlay; S4. The molded insert is sandblasted and sprayed in sequence to form an insert with an Al-Si alloy layer.

[0008] In some specific embodiments, in step S1, the raw materials include pig iron, scrap steel, and alloy materials.

[0009] In some specific embodiments, in step S2, the mold used for casting is a rotating mold cavity of a multi-station centrifugal casting machine, and / or the temperature of the mold is 250~300℃.

[0010] In some specific embodiments, in step S2, the pouring temperature is 1350~1450℃, and the pouring speed is 1750~1850r / min.

[0011] In some specific embodiments, in step S2, the temperature of the cylinder exit is 800~850℃, and / or, the cylinder exit includes cooling, which is carried out on an air-cooled frame, and the temperature of the cylinder exit is 550~600℃.

[0012] In some specific embodiments, in step S4, the sandblasting is performed on a rotary tooling, the rotation frequency of the rotating disk at the base of the rotary tooling is 20~40 r / min, the automatic flipping frequency of the forming insert is 20~40 r / min; and / or, the sandblasting material is 24~32 mesh white corundum, the sandblasting pressure is 0.2~0.4 MPa, and / or, the surface roughness of the insert after sandblasting is not less than 60 μm.

[0013] In some specific embodiments, in step S4, the spraying method is supersonic arc spraying, and / or the raw material for spraying is 1.0~3.0mm aluminum-silicon wire.

[0014] In some specific embodiments, in step S4, the spraying pressure is 0.4~0.6MPa, and / or the spraying speed is 32~38mm / s, and / or the number of sprayings is 5~8; and / or, in step S4, the thickness of the Al-Si alloy layer is 0.1~0.5mm.

[0015] This application also provides a ring prepared by the preparation method described above, comprising a ring substrate and an Al-Si alloy layer formed on the surface of the ring substrate.

[0016] This application also provides an aluminum piston, including an aluminum piston base and an insert ring disposed at the first annular groove of the aluminum piston, wherein the insert ring is an insert ring prepared by the preparation method described above or an insert ring described above.

[0017] This application provides a method for preparing a ring insert. First, raw materials are mixed according to the ring insert's composition ratio and then melted to obtain a ring insert molten metal. Next, the molten metal is poured, demolded, and removed from the cylinder to obtain a tubular ring insert casting blank. Then, the blank is machined, and finally sandblasted and coated to form a ring insert with an Al-Si alloy layer. In this method, the ring insert is prepared according to the above process route, avoiding the oxidation risk caused by high-temperature aluminizing. Simultaneously, the Al-Si alloy layer serves as a transition layer, with a composition highly consistent with the aluminum piston substrate and a perfectly matched coefficient of thermal expansion. This method fundamentally eliminates the interfacial shear stress caused by thermal cycling, significantly improving the thermal fatigue resistance of the insert. The Al-Si alloy layer is free of brittle phases and is formed by spraying, which enhances the interfacial bonding strength with the aluminum piston substrate. Furthermore, the Al-Si alloy layer formed at the junction of the insert and the aluminum piston prepared in this application is tightly bonded to both the insert substrate and the aluminum piston, resulting in a stronger bond between the insert and the aluminum piston. Experimental results show that the bonding strength between the Al-Si alloy layer and the insert can reach over 35 MPa, which is superior to the bonding strength between the aluminum-impregnated layer and the insert substrate. Attached Figure Description

[0018] Figure 1 A photograph of the inlaid ring with an Al-Si alloy layer prepared in Example 1 of the present invention; Figure 2 This is a photograph of the aluminized inlaid ring prepared in comparison to the present invention. Detailed Implementation

[0019] To further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, and not for limiting the scope of the claims of the present invention.

[0020] In view of the bonding problems between the insert ring and the aluminum piston in the prior art, this application provides an insert ring and its preparation method. The preparation method uses casting, machining, sandblasting, and spraying processes to obtain an insert ring with an Al-Si alloy coating. This insert ring is applied to an aluminum piston, forming an Al-Si transition layer at the bonding portion. This transition layer can tightly bond with the insert ring substrate and adapt to the precision structure of the aluminum piston, resulting in a stronger bond between the insert ring and the aluminum piston. It also improves the oxide scale problem caused by high-temperature aluminizing and enhances the thermal fatigue resistance of the insert ring. Specifically, this invention discloses a method for preparing an insert ring, including the following steps: S1. The raw materials are mixed and smelted according to the composition ratio of the ring insert matrix to obtain the ring insert molten metal; the composition of the ring insert matrix, by mass percentage, includes: C: 2.0~3.0%, Si: 1.0~2.8%, Mn: 0.5~1.5%, P: ≤0.2%, S: ≤0.1%, Cr: ≤2.5%, Cu: 5.0~8.0%, Ni: 12~17.5%, with the balance being Fe; S2. The molten metal inlaid with the ring is poured, and after demolding and exiting the cylinder, a tubular inlaid ring casting blank is obtained. S3. The tubular inlay casting blank is machined to obtain the shaped inlay; S4. The molded insert is sandblasted and sprayed in sequence to form an insert with an Al-Si alloy layer.

[0021] In the preparation method of the ring insert, in step S1, the raw materials are mixed and smelted according to the composition ratio of the ring insert matrix to obtain the ring insert molten metal; the composition of the ring insert matrix, by mass percentage, includes: C: 2.0~3.0%, Si: 1.0~2.8%, Mn: 0.5~1.5%, P: ≤0.2%, S: ≤0.1%, Cr: ≤2.5%, Cu: 5.0~8.0%, Ni: 12~17.5%, with the balance being Fe; in this application, the ring insert matrix is ​​a cast iron ring insert, and its composition includes: C: 2.2~2 The composition is as follows: 0.6%, Si: 1.55~2.5%, Mn: 0.8~1.2%, P: ≤0.1%, S: ≤0.1%, Cr: ≤1.6%, Cu: 5.5~7.5%, Ni: 13.5~16.5%, with the balance being Fe. In some specific embodiments, the composition is: C: 2.3~2.4%, Si: 1.8~2.2%, Mn: 0.92~1.0%, P: ≤0.05%, S: ≤0.1%, Cr: ≤1.15%, Cu: 6.0~7.0%, Ni: 14.0~15.5%, with the balance being Fe. The raw materials include pig iron, scrap steel, and alloy materials. In some specific embodiments, the smelting is carried out in a medium-frequency induction furnace. In this application, the smelting is carried out in a manner well known to those skilled in the art, and there are no particular limitations on its specific implementation.

[0022] In step S2, the molten metal for the ring is poured, and after demolding and exiting the cylinder, a tubular ring-shaped casting blank is obtained. The above process is the casting process of the ring. In some specific embodiments, the casting is centrifugal casting. In some specific embodiments, the centrifugal casting involves pouring the molten metal obtained in step S1 into the rotating mold cavity of a multi-station centrifugal casting machine for casting. The multi-station centrifugal casting machine is an automated casting equipment that integrates centrifugal casting technology, a multi-station rotary table, and automatic pouring. It includes a rotating multi-station turntable, an automatic pouring system, a mold and rotating spindle, a cooling system, auxiliary mechanisms, and PLC electrical control. In some specific embodiments, the mold temperature of the rotating mold cavity is 250~300℃; in some specific embodiments, the mold temperature is 260~290℃; in some specific embodiments, the mold temperature is 265~285℃; and in some specific embodiments, the mold temperature is 270~280℃. In some specific embodiments, the pouring temperature is 1350~1450℃; in some specific embodiments, the pouring temperature is 1360~1440℃; in some specific embodiments, the pouring temperature is 1380~1420℃; and in some specific embodiments, the pouring temperature is 1395~1410℃. In some specific embodiments, the pouring rotation speed is 1750~1850 r / min; in some specific embodiments, the pouring rotation speed is 1760~1830 r / min; and in some specific embodiments, the pouring rotation speed is 1780~1800 r / min. In some specific embodiments, the exit temperature is 800~850℃; in some specific embodiments, the exit temperature is 810~840℃; and in some specific embodiments, the exit temperature is 820~830℃. The process after exiting the cylinder includes cooling. In some specific embodiments, the cooling is performed on an air-cooled frame, with the frame temperature being 550-600°C. In other specific embodiments, the frame temperature is 560-596°C, 565-590°C, 570-585°C, and 575-580°C. This process yields a tubular inlaid ring casting blank.

[0023] In step S3, the tubular insert casting blank obtained above is machined to obtain a shaped insert. In this process, the machining is a machining method well known to those skilled in the art, and there are no particular restrictions on its specific implementation. The machining first processes the inner and outer circular contours, then cuts out the initial insert from the end face, and finally processes it to obtain a shaped insert suitable for aluminum pistons.

[0024] In step S4, the shaped insert obtained above is sequentially sandblasted and coated to form an insert with an Al-Si alloy layer. In this step, the sandblasting creates a certain roughness on the surface of the insert, which is beneficial for the subsequent coating preparation. In some specific embodiments, the sandblasting involves feeding the shaped insert into the sandblasting station via a feeding device, clamping the tip on a rotary fixture, and automatically rotating the clamped insert by means of a rotating base and mechanical drive. This sandblasting method is beneficial for the uniformity of sandblasting the insert. During the sandblasting process, the rotation frequency of the rotating base is 20~40 r / min. In some specific embodiments, the rotation frequency is 22~37 r / min, in some specific embodiments, the rotation frequency is 25~35 r / min, in some specific embodiments, the rotation frequency is 28~32 r / min, and in some specific embodiments, the rotation frequency is 29~30 r / min. The automatic rotation frequency of the inlay ring is 20-40 r / min. In some specific embodiments, the automatic rotation frequency is 22-38 r / min; in some specific embodiments, it is 25-36 r / min; in some specific embodiments, it is 27-34 r / min; in some specific embodiments, it is 29-32 r / min; and in some specific embodiments, it is 30-31 r / min. In some specific embodiments, the sandblasting is performed using a high-pressure sandblasting gun, and the sandblasting uses 24-32 mesh white corundum. In some specific embodiments, the sandblasting uses 28-30 mesh. In some specific embodiments, the sandblasting pressure is 0.2-0.4 MPa; in some specific embodiments, it is 0.25-0.35 MPa; and in some specific embodiments, it is 0.28-0.30 MPa. After sandblasting, the surface roughness Rz of the insert ring is not less than 60μm. In some specific embodiments, Rz is 80~150μm, in some specific embodiments, Rz is 90~125μm, and in some specific embodiments, Rz is 100~115μm.

[0025] After the above sandblasting, the surface roughness of the inlay ring is sprayed. In some specific embodiments, the spraying is performed at the spraying station. Specifically, the clamping tip is placed on a rotary fixture, and the clamped shaped inlay ring is automatically rotated by the base rotating turntable and mechanical drive. In some specific embodiments, the rotation frequency of the base rotating turntable is 20~40 r / min, in some specific embodiments it is 22~37 r / min, in some specific embodiments it is 25~35 r / min, in some specific embodiments it is 28~33 r / min, and in some specific embodiments it is 29~30 r / min. In some specific embodiments, the automatic rotation frequency of the insert ring is 20~40 r / min; in some specific embodiments, the automatic rotation frequency is 23~38 r / min; in some specific embodiments, the automatic rotation frequency is 25~36 r / min; in some specific embodiments, the automatic rotation frequency is 27~35 r / min; in some specific embodiments, the automatic rotation frequency is 29~33 r / min; and in some specific embodiments, the automatic rotation frequency is 30~32 r / min. In some specific embodiments, the spraying is performed using supersonic arc spraying, and the spraying material is selected from silicon-aluminum wire. In some specific embodiments, the silicon-aluminum wire contains 11.2~12.8 wt% silicon; in some specific embodiments, the silicon-aluminum wire contains 12.0~12.5 wt% silicon. In some specific embodiments, the length of the silicon-aluminum wire is 1.0~3.0 mm; and in some specific embodiments, the length of the silicon-aluminum wire is 1.5~2.0 mm. During the spraying process, when the silicon-aluminum wire comes into contact with the positive and negative power supplies, the resulting electric arc melts the metal. The molten silicon-aluminum wire, under the action of compressed air, is blown onto the surface of the wear-resistant insert to form a coating. This process is repeated 5-8 times to form a stacked layered structure. In some specific embodiments, the spray gun pressure is 0.4-0.6 MPa; in others, it is 0.45-0.50 MPa. In some embodiments, the spraying speed is 32-38 mm / s; in others, it is 33-36 mm / s; and in still others, it is 34-35 mm / s. In some embodiments, the number of spraying passes is 6-7.After the above-described spraying process, an insert ring with an Al-Si alloy layer is obtained. In some specific embodiments, the thickness of the Al-Si alloy layer is 0.1~0.5 mm, in some specific embodiments it is 0.2~0.4 mm, and in some specific embodiments it is 0.3~0.4 mm. In this application, the insert ring substrate is cast iron. By employing the above-described spraying method combined with the surface roughness obtained by sandblasting, the Al-Si alloy layer has high bonding strength on the surface of the cast iron insert ring, avoiding the problems of insufficient bonding strength and easy separation when the Al-Si alloy layer and the cast iron insert ring have different compositions.

[0026] This application also provides a ring prepared by the above method, which includes a ring substrate and an Al-Si alloy layer formed on the surface of the ring substrate.

[0027] In this application, the insert base is a cast iron insert, and the thickness of the Al-Si alloy layer is 0.1~0.5mm.

[0028] Furthermore, this application also provides an aluminum piston, which includes an aluminum piston base and an insert ring disposed at the first annular groove of the aluminum piston, the insert ring being the insert ring described in the above-mentioned scheme.

[0029] In the aluminum piston, the Al-Si alloy layer on the surface of the insert mates with the first annular groove of the aluminum piston.

[0030] This invention obtains a wear-resistant insert with an Al-Si coating through centrifugal casting, machining, sandblasting, and spraying. The wear-resistant insert obtained according to the above process avoids the oxidation risk associated with high-temperature aluminizing. The Al-Si coating, as a transition layer, has a composition highly consistent with the aluminum piston substrate and a perfectly matched coefficient of thermal expansion, fundamentally eliminating interfacial shear stress caused by thermal cycling and significantly improving thermal fatigue resistance. Furthermore, the coating is free of brittle phases, enhancing the interfacial bonding strength with the aluminum piston substrate. Simultaneously, the transition layer formed at the junction with the aluminum piston in the wear-resistant insert obtained by the method of this invention is tightly bonded to both the insert body and the piston body, resulting in a stronger bond between the wear-resistant insert and the aluminum piston. The bonding strength between the coating and the insert can reach over 35 MPa, which is superior to the bonding strength between the aluminized layer and the insert body.

[0031] To further understand the present invention, the preparation method of the inlaid ring provided by the present invention will be described in detail below with reference to the embodiments. The scope of protection of the present invention is not limited by the following embodiments.

[0032] Example

[0033] S1. The pig iron, scrap steel and alloy materials prepared in proportion are put into a medium frequency induction furnace for smelting to obtain a ring-inlaid molten metal. The composition of the ring-inlaid molten metal, by mass percentage, includes: C: 2.6%, Si: 1.55%, Mn: 0.92%, Ni: 15.5%, P: 0.036%, S: 0.02%, Cr: 1.15%, Cu: 6.95%, with the balance being Fe. S2. The molten alloy obtained in step S1 is poured into the rotating mold cavity of a multi-station centrifugal casting machine. The mold temperature is 262℃, the pouring temperature is 1395℃, and the pouring speed is 1760r / min. After water cooling, the mold is demolded and removed from the cylinder at a temperature of 834℃. After removal from the cylinder, the mold is cooled on an air cooling rack at a temperature of 596℃, resulting in a tubular inlaid ring casting blank. S3. Machining the tubular inlay casting blank obtained in step S2, machining the inner and outer circular contours, and then cutting out the shaped wear-resistant inlay from the end face. Continue to process the tubular blank until the shaped inlay is obtained. S4. The shaped insert obtained in step S3 is fed into the sandblasting station through a feeding device and clamped on a turntable fixture. The clamped shaped wear-resistant insert is automatically rotated by the rotating turntable of the base and the mechanical drive. The rotation frequency of the rotating turntable of the base is 25 r / min, and the automatic rotation frequency of the insert is 25 r / min. Sandblasting is carried out using a high-pressure sandblasting gun, and 24~32 mesh white corundum is used for roughening. The sandblasting pressure is 0.35MPa to ensure that the circumferential surface is uniformly sprayed. After sandblasting, the surface roughness Rz of the insert is 125μm. After sandblasting, the inlay is moved to the spraying station by a robotic arm and clamped onto a rotary fixture. The clamped wear-resistant inlay is automatically rotated by the rotating base and mechanical drive. The rotation frequency of the rotating base and the automatic rotation frequency of the inlay is 25 r / min. After cleaning the inlay and the clamping fixture with compressed air, a supersonic arc spraying method is used. When the 2.0 mm aluminum-silicon wire comes into contact with the positive and negative power supply, the generated arc melts the metal. The molten metal is blown onto the surface of the wear-resistant inlay by compressed air, forming a stacked layered Al-Si alloy layer after spraying. The spray gun pressure is 0.5 MPa, the spraying speed is 35 mm / s, the spraying is repeated 7 times, and the thickness of the Al-Si alloy layer is 0.3962 mm.

[0034] Figure 1 The image shows a photograph of the inlaid ring with an Al-Si alloy layer prepared in this embodiment. As can be seen from the image, the Al-Si alloy layer is tightly bonded to the inlaid ring without any pores.

[0035] Comparative Example 1

[0036] A wear-resistant insert is prepared by using an aluminum impregnation process to obtain a wear-resistant insert with an aluminum alloy metal layer. S1. The pig iron, scrap steel and alloy materials prepared in proportion are put into a medium frequency induction furnace for smelting to obtain a ring-inlaid molten metal. The composition of the ring-inlaid molten metal, by mass percentage, includes: C: 2.6%, Si: 1.55%, Mn: 0.92%, Ni: 15.5%, P: 0.036%, S: 0.02%, Cr: 1.15%, Cu: 6.95%, with the balance being Fe. S2. The molten alloy obtained in step S1 is poured into the rotating mold cavity of a multi-station centrifugal casting machine. The mold temperature is 262℃, the pouring temperature is 1395℃, and the pouring speed is 1760r / min. After water cooling, the mold is demolded and removed from the cylinder at a temperature of 834℃. After removal from the cylinder, the mold is cooled on an air-cooling frame at a temperature of 596℃, resulting in a tubular inlaid ring casting blank. S3. Machining the tubular inlay casting blank obtained in step S2, machining the inner and outer circular contours, cutting out the shaped wear-resistant inlay from the end face, and then continuing to process the tubular blank until the shaped inlay is obtained. S4. After cleaning the surface of the molded wear-resistant insert, immerse it in molten aluminum-silicon piston alloy for about 2 to 5 minutes to form an aluminum layer on the surface of the insert with a thickness of 0.4338 mm.

[0037] Figure 2 A photograph of the aluminized inlaid ring prepared for this comparative example, by Figure 2 It can be seen that there are tiny pores at the interface between the aluminum layer and the inlay ring.

[0038] Test case

[0039] The castings prepared according to the embodiments and comparative examples of the present invention were subjected to microstructure and performance tests according to the following methods. The results are shown in Tables 1 and 2. The ring bodies used in the embodiments and comparative examples were from the same production batch of rings. Metallographic structure testing: Metallographic structure testing shall be conducted in accordance with GB / T7216 "Metallographic Examination of Gray Cast Iron"; Hardness testing: Hardness was tested according to GB / T 231.1 "Metallic materials - Brinell hardness test - Part 1: Test method"; Bonding strength test: After bonding the test screw to the sample block with adhesive, apply a gradually increasing tensile force to the test screw using a coating adhesion tester until the coating separates from the sample block substrate. Read the value on the dial, which can be directly converted into the bonding strength between the coating and the surface of the inlay substrate. Thermal expansion deformation test: After the insert is placed in the heat treatment furnace, the furnace temperature is raised from 25℃ to 90℃ in 30 minutes, and the furnace temperature is held at 90℃ for 2 hours; the room temperature measurement temperature is 22℃, the temperature at the beginning of the hot measurement is 90℃, and the temperature at the end of the measurement is 76℃; the measurement results include errors caused by the temperature rise of the gauge and the temperature drop of the cylinder during the measurement process, and these two errors cannot be eliminated.

[0040] The test results are shown in Tables 1 and 2. Table 1. Test results data of the inlay rings prepared in the examples and comparative examples.

[0041] Table 2. Thermal expansion and deformation data of the inserts prepared in the examples and comparative examples.

[0042] As shown in Tables 1 and 2, the present invention prepared wear-resistant inserts with Al-Si alloy layers through centrifugal casting, machining, sandblasting, and spraying processes. Compared with the inserts prepared by the aluminizing process provided in the comparative example, the bonding strength between the insert substrate and the Al-Si alloy layer of the insert prepared in the example can reach up to 40.9 MPa, which is much higher than the bonding strength between the insert substrate and the coating of the insert prepared in the comparative example. At the same time, the thermal expansion deformation of the insert prepared in the example after hot state is also lower than that of the insert prepared in the comparative example.

[0043] Therefore, the insert prepared according to the process flow of this application avoids the oxidation risk caused by high-temperature aluminizing. The Al-Si coating, as a transition layer, has a composition highly consistent with the aluminum piston substrate and a perfect match in thermal expansion coefficient, fundamentally eliminating the interfacial shear stress caused by thermal cycling and significantly improving the resistance to thermal fatigue. Moreover, the Al-Si coating has no brittle phase, which improves the interfacial bonding strength with the aluminum piston substrate. At the same time, the Al-Si transition layer formed at the junction with the aluminum piston in the insert prepared by the method of this invention is tightly bonded to the insert body and the piston body, making the wear-resistant insert bonded to the aluminum piston stronger. The bonding strength between the coating and the insert can reach more than 35 MPa, which is also better than the bonding strength between the aluminized layer and the insert body.

[0044] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

[0045] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a setting ring, comprising the following steps: S1. The raw materials are mixed and smelted according to the composition ratio of the ring insert matrix to obtain the ring insert molten metal; the composition of the ring insert matrix, by mass percentage, includes: C: 2.0~3.0%, Si: 1.0~2.8%, Mn: 0.5~1.5%, P: ≤0.2%, S: ≤0.1%, Cr: ≤2.5%, Cu: 5.0~8.0%, Ni: 12~17.5%, with the balance being Fe; S2. The molten metal inlaid with the ring is poured, and after demolding and exiting the cylinder, a tubular inlaid ring casting blank is obtained. S3. The tubular inlay casting blank is machined to obtain the shaped inlay; S4. The molded insert is sandblasted and sprayed in sequence to form an insert with an Al-Si alloy layer.

2. The preparation method according to claim 1, characterized in that, In step S1, the raw materials include pig iron, scrap steel, and alloy materials.

3. The preparation method according to claim 1, characterized in that, In step S2, the mold used for casting is a rotating mold cavity of a multi-station centrifugal casting machine, and / or the temperature of the mold is 250~300℃.

4. The preparation method according to claim 3, characterized in that, In step S2, the pouring temperature is 1350~1450℃, and the pouring speed is 1750~1850r / min.

5. The preparation method according to claim 3, characterized in that, In step S2, the temperature of the cylinder exit is 800~850℃, and / or, the cylinder exit includes cooling, which is carried out on an air-cooled frame, and the temperature of the cylinder exit is 550~600℃.

6. The preparation method according to claim 1, characterized in that, In step S4, the sandblasting is performed on a rotary fixture, the base of which has a rotating frequency of 20-40 r / min, and the automatic flipping frequency of the forming insert is 20-40 r / min; and / or, the sandblasting material is 24-32 mesh white corundum, the sandblasting pressure is 0.2-0.4 MPa, and / or, the surface roughness of the sandblasted insert is not less than 60 μm.

7. The preparation method according to claim 1 or 6, characterized in that, In step S4, the spraying method is supersonic arc spraying, and / or the raw material for spraying is 1.0~3.0mm aluminum-silicon wire.

8. The preparation method according to claim 7, characterized in that, In step S4, the spraying pressure is 0.4~0.6MPa, and / or the spraying speed is 32~38mm / s, and / or the number of spraying passes is 5~8; and / or, in step S4, the thickness of the Al-Si alloy layer is 0.1~0.5mm.

9. A ring prepared by the preparation method according to any one of claims 1 to 8, comprising a ring substrate and an Al-Si alloy layer formed on the surface of the ring substrate.

10. An aluminum piston, comprising an aluminum piston base and an insert disposed at a first annular groove of the aluminum piston, wherein the insert is an insert prepared by the preparation method according to any one of claims 1 to 8 or an insert according to claim 9.

Images